2023-10-09 23:08:28

by Dmitry Safonov

Subject: [PATCH v14 net-next 00/23] net/tcp: Add TCP-AO support

Hi,

This is version 14 of TCP-AO support. More-or-less quick update from v13
addressing Jonathan review comment on unreadable list-tables in TCP-AO
Documentation/ page.

There's one Sparse warning introduced by tcp_sigpool_start():
__cond_acquires() seems to currently being broken. I've described
the reasoning for it on v9 cover letter. Also, checkpatch.pl warnings
were addressed, but yet I've left the ones that are more personal
preferences (i.e. 80 columns limit). Please, ping me if you have
a strong feeling about one of them.

The following changes since commit 19537e125cc7cf2da43a606f5bcebbe0c9aea4cc:

net: bcmgenet: Remove custom ndo_poll_controller() (2023-10-08 17:42:43 +0100)

are available in the Git repository at:

[email protected]:0x7f454c46/linux.git tcp-ao-v14

for you to fetch changes up to e7b89a5efe68fc78ef8bc3be2bce60a9d35ac4be:

Documentation/tcp: Add TCP-AO documentation (2023-10-09 23:31:25 +0100)

----------------------------------------------------------------

And another branch with selftests, that will be sent later separately:
[email protected]:0x7f454c46/linux.git tcp-ao-v14-with-selftests

Thanks for your time and reviews,
Dmitry

--- Changelog ---

Changes from v13:
- Converted Documentation/ page from human unreadable list-table::
to grid-table(s) (Jonathan)

Version 13: https://lore.kernel.org/all/[email protected]/T/#u

Changes from v12:
- Separate TCP-AO sign from __tcp_transmit_skb() into a separate
function for code locality and readability (Paolo)
- Add TCP-AO self-connect selftest, which by its nature is a selftest
for TCP simultaneous open, use different keyids and check tcp repair
- Fix simultaneous open: take correct ISNs for verification,
pre-calculate sending traffic key on SYN-ACK, calculate receiving
traffic key before going into TCP_ESTABLISHED
- Use kfree_sensitive() for hardening purposes
- Use READ_ONCE() on sk->sk_family when not under socket lock to prevent
any possible race with IPV6_ADDRFORM

Version 12: https://lore.kernel.org/all/[email protected]/T/#u

Changes from v11:
- Define (struct tcp_key) for tcp-fast path and detect by type what key
was used. This also benefits from TCP-MD5/TCP-AO static branches (Eric)
- Remove sk_gso_disable() from TCP-AO fast-path in __tcp_transmit_skb()
(Eric)
- Don't leak skb on failed kmalloc() in __tcp_transmit_skb() (Eric)
- skb_dst_drop() is not necessary as kfree_skb() calls it (Eric)
- Don't dereference tcp_ao_key in net_warn_ratelimited(), outside of
rcu_read_lock() (Eric)

Version 11: https://lore.kernel.org/all/[email protected]/T/#u

Changes from v10:
- Make seq (u32) in tcp_ao_prepare_reset() and declare the argument
in "net/tcp: Add TCP-AO SNE support", where it gets used (Simon)
- Fix rebase artifact in tcp_v6_reqsk_send_ack(), which adds
compile-error on a patch in the middle of series (Simon)
- Another rebase artifact in tcp_v6_reqsk_send_ack() that makes
keyid, requested by peer on ipv6 reqsk ACKs not respected (Simon)

Version 10: https://lore.kernel.org/all/[email protected]/T/#u

The pre-v10 changelog is on version 10 cover-letter.

Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Bob Gilligan <[email protected]>
Cc: Dan Carpenter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: David Laight <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Dmitry Safonov <[email protected]>
Cc: Donald Cassidy <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Francesco Ruggeri <[email protected]>
Cc: Gaillardetz, Dominik <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: Ivan Delalande <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Leonard Crestez <[email protected]>
Cc: Nassiri, Mohammad <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Salam Noureddine <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Tetreault, Francois <[email protected]>
Cc: [email protected]
Cc: [email protected]

Dmitry Safonov (23):
net/tcp: Prepare tcp_md5sig_pool for TCP-AO
net/tcp: Add TCP-AO config and structures
net/tcp: Introduce TCP_AO setsockopt()s
net/tcp: Prevent TCP-MD5 with TCP-AO being set
net/tcp: Calculate TCP-AO traffic keys
net/tcp: Add TCP-AO sign to outgoing packets
net/tcp: Add tcp_parse_auth_options()
net/tcp: Add AO sign to RST packets
net/tcp: Add TCP-AO sign to twsk
net/tcp: Wire TCP-AO to request sockets
net/tcp: Sign SYN-ACK segments with TCP-AO
net/tcp: Verify inbound TCP-AO signed segments
net/tcp: Add TCP-AO segments counters
net/tcp: Add TCP-AO SNE support
net/tcp: Add tcp_hash_fail() ratelimited logs
net/tcp: Ignore specific ICMPs for TCP-AO connections
net/tcp: Add option for TCP-AO to (not) hash header
net/tcp: Add TCP-AO getsockopt()s
net/tcp: Allow asynchronous delete for TCP-AO keys (MKTs)
net/tcp: Add static_key for TCP-AO
net/tcp: Wire up l3index to TCP-AO
net/tcp: Add TCP_AO_REPAIR
Documentation/tcp: Add TCP-AO documentation

Documentation/networking/index.rst | 1 +
Documentation/networking/tcp_ao.rst | 444 +++++
include/linux/sockptr.h | 23 +
include/linux/tcp.h | 30 +-
include/net/dropreason-core.h | 30 +
include/net/tcp.h | 288 +++-
include/net/tcp_ao.h | 361 ++++
include/uapi/linux/snmp.h | 5 +
include/uapi/linux/tcp.h | 105 ++
net/ipv4/Kconfig | 17 +
net/ipv4/Makefile | 2 +
net/ipv4/proc.c | 5 +
net/ipv4/syncookies.c | 4 +
net/ipv4/tcp.c | 246 +--
net/ipv4/tcp_ao.c | 2389 +++++++++++++++++++++++++++
net/ipv4/tcp_input.c | 98 +-
net/ipv4/tcp_ipv4.c | 363 +++-
net/ipv4/tcp_minisocks.c | 50 +-
net/ipv4/tcp_output.c | 236 ++-
net/ipv4/tcp_sigpool.c | 358 ++++
net/ipv6/Makefile | 1 +
net/ipv6/syncookies.c | 5 +
net/ipv6/tcp_ao.c | 168 ++
net/ipv6/tcp_ipv6.c | 374 +++--
24 files changed, 5168 insertions(+), 435 deletions(-)
create mode 100644 Documentation/networking/tcp_ao.rst
create mode 100644 include/net/tcp_ao.h
create mode 100644 net/ipv4/tcp_ao.c
create mode 100644 net/ipv4/tcp_sigpool.c
create mode 100644 net/ipv6/tcp_ao.c


base-commit: 19537e125cc7cf2da43a606f5bcebbe0c9aea4cc
--
2.42.0

2023-10-09 23:08:44

by Dmitry Safonov

Subject: [PATCH v14 net-next 09/23] net/tcp: Add TCP-AO sign to twsk

Add support for sockets in time-wait state.
ao_info as well as all keys are inherited on transition to time-wait
socket. The lifetime of ao_info is now protected by ref counter, so
that tcp_ao_destroy_sock() will destruct it only when the last user is
gone.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/linux/tcp.h | 3 ++
include/net/tcp_ao.h | 11 ++++-
net/ipv4/tcp_ao.c | 46 +++++++++++++++++---
net/ipv4/tcp_ipv4.c | 92 +++++++++++++++++++++++++++++++---------
net/ipv4/tcp_minisocks.c | 4 +-
net/ipv4/tcp_output.c | 2 +-
net/ipv6/tcp_ipv6.c | 72 ++++++++++++++++++++++---------
7 files changed, 181 insertions(+), 49 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c38778b0baa0..51458219be4e 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -512,6 +512,9 @@ struct tcp_timewait_sock {
#ifdef CONFIG_TCP_MD5SIG
struct tcp_md5sig_key *tw_md5_key;
#endif
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info __rcu *ao_info;
+#endif
};

static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 629ab0365b83..af2caf7e76fc 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -85,6 +85,7 @@ struct tcp_ao_info {
__unused :31;
__be32 lisn;
__be32 risn;
+ atomic_t refcnt; /* Protects twsk destruction */
struct rcu_head rcu;
};

@@ -124,7 +125,8 @@ struct tcp_ao_key *tcp_ao_established_key(struct tcp_ao_info *ao,
int sndid, int rcvid);
int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp);
-void tcp_ao_destroy_sock(struct sock *sk);
+void tcp_ao_destroy_sock(struct sock *sk, bool twsk);
+void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr,
int family, int sndid, int rcvid);
@@ -182,7 +184,7 @@ static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
return NULL;
}

-static inline void tcp_ao_destroy_sock(struct sock *sk)
+static inline void tcp_ao_destroy_sock(struct sock *sk, bool twsk)
{
}

@@ -194,6 +196,11 @@ static inline void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb)
{
}

+static inline void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw,
+ struct tcp_sock *tp)
+{
+}
+
static inline void tcp_ao_connect_init(struct sock *sk)
{
}
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index df59924c3828..00d21f6242de 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -159,6 +159,7 @@ static struct tcp_ao_info *tcp_ao_alloc_info(gfp_t flags)
if (!ao)
return NULL;
INIT_HLIST_HEAD(&ao->head);
+ atomic_set(&ao->refcnt, 1);

return ao;
}
@@ -176,27 +177,54 @@ static void tcp_ao_key_free_rcu(struct rcu_head *head)
kfree_sensitive(key);
}

-void tcp_ao_destroy_sock(struct sock *sk)
+void tcp_ao_destroy_sock(struct sock *sk, bool twsk)
{
struct tcp_ao_info *ao;
struct tcp_ao_key *key;
struct hlist_node *n;

- ao = rcu_dereference_protected(tcp_sk(sk)->ao_info, 1);
- tcp_sk(sk)->ao_info = NULL;
+ if (twsk) {
+ ao = rcu_dereference_protected(tcp_twsk(sk)->ao_info, 1);
+ tcp_twsk(sk)->ao_info = NULL;
+ } else {
+ ao = rcu_dereference_protected(tcp_sk(sk)->ao_info, 1);
+ tcp_sk(sk)->ao_info = NULL;
+ }

- if (!ao)
+ if (!ao || !atomic_dec_and_test(&ao->refcnt))
return;

hlist_for_each_entry_safe(key, n, &ao->head, node) {
hlist_del_rcu(&key->node);
- atomic_sub(tcp_ao_sizeof_key(key), &sk->sk_omem_alloc);
+ if (!twsk)
+ atomic_sub(tcp_ao_sizeof_key(key), &sk->sk_omem_alloc);
call_rcu(&key->rcu, tcp_ao_key_free_rcu);
}

kfree_rcu(ao, rcu);
}

+void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp)
+{
+ struct tcp_ao_info *ao_info = rcu_dereference_protected(tp->ao_info, 1);
+
+ if (ao_info) {
+ struct tcp_ao_key *key;
+ struct hlist_node *n;
+ int omem = 0;
+
+ hlist_for_each_entry_safe(key, n, &ao_info->head, node) {
+ omem += tcp_ao_sizeof_key(key);
+ }
+
+ atomic_inc(&ao_info->refcnt);
+ atomic_sub(omem, &(((struct sock *)tp)->sk_omem_alloc));
+ rcu_assign_pointer(tcptw->ao_info, ao_info);
+ } else {
+ tcptw->ao_info = NULL;
+ }
+}
+
/* 4 tuple and ISNs are expected in NBO */
static int tcp_v4_ao_calc_key(struct tcp_ao_key *mkt, u8 *key,
__be32 saddr, __be32 daddr,
@@ -519,8 +547,9 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
struct tcp_ao_key *rnext_key;

if (sk->sk_state == TCP_TIME_WAIT)
- return -1;
- ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
+ ao_info = rcu_dereference(tcp_twsk(sk)->ao_info);
+ else
+ ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
if (!ao_info)
return -ENOENT;

@@ -909,6 +938,9 @@ static struct tcp_ao_info *setsockopt_ao_info(struct sock *sk)
if (sk_fullsock(sk)) {
return rcu_dereference_protected(tcp_sk(sk)->ao_info,
lockdep_sock_is_held(sk));
+ } else if (sk->sk_state == TCP_TIME_WAIT) {
+ return rcu_dereference_protected(tcp_twsk(sk)->ao_info,
+ lockdep_sock_is_held(sk));
}
return ERR_PTR(-ESOCKTNOSUPPORT);
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 6a7a7736ba6f..d98a943a4206 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -910,17 +910,13 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
static void tcp_v4_send_ack(const struct sock *sk,
struct sk_buff *skb, u32 seq, u32 ack,
u32 win, u32 tsval, u32 tsecr, int oif,
- struct tcp_md5sig_key *key,
+ struct tcp_key *key,
int reply_flags, u8 tos, u32 txhash)
{
const struct tcphdr *th = tcp_hdr(skb);
struct {
struct tcphdr th;
- __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
-#ifdef CONFIG_TCP_MD5SIG
- + (TCPOLEN_MD5SIG_ALIGNED >> 2)
-#endif
- ];
+ __be32 opt[(MAX_TCP_OPTION_SPACE >> 2)];
} rep;
struct net *net = sock_net(sk);
struct ip_reply_arg arg;
@@ -951,7 +947,7 @@ static void tcp_v4_send_ack(const struct sock *sk,
rep.th.window = htons(win);

#ifdef CONFIG_TCP_MD5SIG
- if (key) {
+ if (tcp_key_is_md5(key)) {
int offset = (tsecr) ? 3 : 0;

rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
@@ -962,9 +958,27 @@ static void tcp_v4_send_ack(const struct sock *sk,
rep.th.doff = arg.iov[0].iov_len/4;

tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
- key, ip_hdr(skb)->saddr,
+ key->md5_key, ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr, &rep.th);
}
+#endif
+#ifdef CONFIG_TCP_AO
+ if (tcp_key_is_ao(key)) {
+ int offset = (tsecr) ? 3 : 0;
+
+ rep.opt[offset++] = htonl((TCPOPT_AO << 24) |
+ (tcp_ao_len(key->ao_key) << 16) |
+ (key->ao_key->sndid << 8) |
+ key->rcv_next);
+ arg.iov[0].iov_len += round_up(tcp_ao_len(key->ao_key), 4);
+ rep.th.doff = arg.iov[0].iov_len / 4;
+
+ tcp_ao_hash_hdr(AF_INET, (char *)&rep.opt[offset],
+ key->ao_key, key->traffic_key,
+ (union tcp_ao_addr *)&ip_hdr(skb)->saddr,
+ (union tcp_ao_addr *)&ip_hdr(skb)->daddr,
+ &rep.th, key->sne);
+ }
#endif
arg.flags = reply_flags;
arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
@@ -998,18 +1012,50 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
{
struct inet_timewait_sock *tw = inet_twsk(sk);
struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+ struct tcp_key key = {};
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao_info;
+
+ /* FIXME: the segment to-be-acked is not verified yet */
+ ao_info = rcu_dereference(tcptw->ao_info);
+ if (ao_info) {
+ const struct tcp_ao_hdr *aoh;
+
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh)) {
+ inet_twsk_put(tw);
+ return;
+ }
+
+ if (aoh)
+ key.ao_key = tcp_ao_established_key(ao_info, aoh->rnext_keyid, -1);
+ }
+ if (key.ao_key) {
+ struct tcp_ao_key *rnext_key;
+
+ key.traffic_key = snd_other_key(key.ao_key);
+ rnext_key = READ_ONCE(ao_info->rnext_key);
+ key.rcv_next = rnext_key->rcvid;
+ key.type = TCP_KEY_AO;
+#else
+ if (0) {
+#endif
+#ifdef CONFIG_TCP_MD5SIG
+ } else if (static_branch_unlikely(&tcp_md5_needed.key)) {
+ key.md5_key = tcp_twsk_md5_key(tcptw);
+ if (key.md5_key)
+ key.type = TCP_KEY_MD5;
+#endif
+ }

tcp_v4_send_ack(sk, skb,
tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
tcp_time_stamp_raw() + tcptw->tw_ts_offset,
tcptw->tw_ts_recent,
- tw->tw_bound_dev_if,
- tcp_twsk_md5_key(tcptw),
+ tw->tw_bound_dev_if, &key,
tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
tw->tw_tos,
- tw->tw_txhash
- );
+ tw->tw_txhash);

inet_twsk_put(tw);
}
@@ -1017,8 +1063,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
{
- const union tcp_md5_addr *addr;
- int l3index;
+ struct tcp_key key = {};

/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
* sk->sk_state == TCP_SYN_RECV -> for Fast Open.
@@ -1031,15 +1076,24 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
* exception of <SYN> segments, MUST be right-shifted by
* Rcv.Wind.Shift bits:
*/
- addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
- l3index = tcp_v4_sdif(skb) ? inet_iif(skb) : 0;
+#ifdef CONFIG_TCP_MD5SIG
+ if (static_branch_unlikely(&tcp_md5_needed.key)) {
+ const union tcp_md5_addr *addr;
+ int l3index;
+
+ addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
+ l3index = tcp_v4_sdif(skb) ? inet_iif(skb) : 0;
+ key.md5_key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
+ if (key.md5_key)
+ key.type = TCP_KEY_MD5;
+ }
+#endif
tcp_v4_send_ack(sk, skb, seq,
tcp_rsk(req)->rcv_nxt,
req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
READ_ONCE(req->ts_recent),
- 0,
- tcp_md5_do_lookup(sk, l3index, addr, AF_INET),
+ 0, &key,
inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
ip_hdr(skb)->tos,
READ_ONCE(tcp_rsk(req)->txhash));
@@ -2402,7 +2456,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
rcu_assign_pointer(tp->md5sig_info, NULL);
}
#endif
- tcp_ao_destroy_sock(sk);
+ tcp_ao_destroy_sock(sk, false);

/* Clean up a referenced TCP bind bucket. */
if (inet_csk(sk)->icsk_bind_hash)
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 37aff812ca18..c60a84526733 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -279,7 +279,7 @@ static void tcp_time_wait_init(struct sock *sk, struct tcp_timewait_sock *tcptw)
void tcp_time_wait(struct sock *sk, int state, int timeo)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
- const struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
struct net *net = sock_net(sk);
struct inet_timewait_sock *tw;

@@ -315,6 +315,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
#endif

tcp_time_wait_init(sk, tcptw);
+ tcp_ao_time_wait(tcptw, tp);

/* Get the TIME_WAIT timeout firing. */
if (timeo < rto)
@@ -369,6 +370,7 @@ void tcp_twsk_destructor(struct sock *sk)
call_rcu(&twsk->tw_md5_key->rcu, tcp_md5_twsk_free_rcu);
}
#endif
+ tcp_ao_destroy_sock(sk, true);
}
EXPORT_SYMBOL_GPL(tcp_twsk_destructor);

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 23fce35a6f65..edd3e8665c1b 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3997,7 +3997,7 @@ int tcp_connect(struct sock *sk)
* then free up ao_info if allocated.
*/
if (needs_md5) {
- tcp_ao_destroy_sock(sk);
+ tcp_ao_destroy_sock(sk, false);
} else if (needs_ao) {
tcp_clear_md5_list(sk);
kfree(rcu_replace_pointer(tp->md5sig_info, NULL,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 594eb074e5e5..7a871b774730 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -777,13 +777,6 @@ static int tcp_v6_md5_hash_skb(char *md5_hash,
memset(md5_hash, 0, 16);
return 1;
}
-#else /* CONFIG_TCP_MD5SIG */
-static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
- const struct in6_addr *addr,
- int l3index)
-{
- return NULL;
-}
#endif

static void tcp_v6_init_req(struct request_sock *req,
@@ -1131,39 +1124,81 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)

static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq,
u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,
- struct tcp_md5sig_key *md5_key, u8 tclass,
+ struct tcp_key *key, u8 tclass,
__be32 label, u32 priority, u32 txhash)
{
- struct tcp_key key = {
- .md5_key = md5_key,
- .type = md5_key ? TCP_KEY_MD5 : TCP_KEY_NONE,
- };
-
tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, 0,
- tclass, label, priority, txhash, &key);
+ tclass, label, priority, txhash, key);
}

static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
{
struct inet_timewait_sock *tw = inet_twsk(sk);
struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+ struct tcp_key key = {};
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao_info;
+
+ /* FIXME: the segment to-be-acked is not verified yet */
+ ao_info = rcu_dereference(tcptw->ao_info);
+ if (ao_info) {
+ const struct tcp_ao_hdr *aoh;
+
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
+ goto out;
+ if (aoh) {
+ key.ao_key = tcp_ao_established_key(ao_info,
+ aoh->rnext_keyid, -1);
+ }
+ }
+ if (key.ao_key) {
+ struct tcp_ao_key *rnext_key;
+
+ key.traffic_key = snd_other_key(key.ao_key);
+ /* rcv_next switches to our rcv_next */
+ rnext_key = READ_ONCE(ao_info->rnext_key);
+ key.rcv_next = rnext_key->rcvid;
+ key.type = TCP_KEY_AO;
+#else
+ if (0) {
+#endif
+#ifdef CONFIG_TCP_MD5SIG
+ } else if (static_branch_unlikely(&tcp_md5_needed.key)) {
+ key.md5_key = tcp_twsk_md5_key(tcptw);
+ if (key.md5_key)
+ key.type = TCP_KEY_MD5;
+#endif
+ }

tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
tcp_time_stamp_raw() + tcptw->tw_ts_offset,
- tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
+ tcptw->tw_ts_recent, tw->tw_bound_dev_if, &key,
tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel), tw->tw_priority,
tw->tw_txhash);

+#ifdef CONFIG_TCP_AO
+out:
+#endif
inet_twsk_put(tw);
}

static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
{
- int l3index;
+ struct tcp_key key = {};

- l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
+#ifdef CONFIG_TCP_MD5SIG
+ if (static_branch_unlikely(&tcp_md5_needed.key)) {
+ int l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
+
+ key.md5_key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr,
+ l3index);
+ if (key.md5_key)
+ key.type = TCP_KEY_MD5;
+ }
+#endif

/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
* sk->sk_state == TCP_SYN_RECV -> for Fast Open.
@@ -1179,8 +1214,7 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
READ_ONCE(req->ts_recent), sk->sk_bound_dev_if,
- tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr, l3index),
- ipv6_get_dsfield(ipv6_hdr(skb)), 0,
+ &key, ipv6_get_dsfield(ipv6_hdr(skb)), 0,
READ_ONCE(sk->sk_priority),
READ_ONCE(tcp_rsk(req)->txhash));
}
--
2.42.0

2023-10-09 23:08:53

by Dmitry Safonov

Subject: [PATCH v14 net-next 13/23] net/tcp: Add TCP-AO segments counters

Introduce segment counters that are useful for troubleshooting/debugging
as well as for writing tests.
Now there are global snmp counters as well as per-socket and per-key.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/dropreason-core.h | 15 +++++++++++----
include/net/tcp.h | 15 +++++++++++----
include/net/tcp_ao.h | 10 ++++++++++
include/uapi/linux/snmp.h | 4 ++++
include/uapi/linux/tcp.h | 8 +++++++-
net/ipv4/proc.c | 4 ++++
net/ipv4/tcp_ao.c | 30 +++++++++++++++++++++++++++---
net/ipv4/tcp_ipv4.c | 2 +-
net/ipv6/tcp_ipv6.c | 4 ++--
9 files changed, 77 insertions(+), 15 deletions(-)

diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index a01e1860fe25..efb6ea5ffb1e 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -167,17 +167,24 @@ enum skb_drop_reason {
*/
SKB_DROP_REASON_TCP_MD5FAILURE,
/**
- * @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected
+ * @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected,
+ * corresponding to LINUX_MIB_TCPAOREQUIRED
*/
SKB_DROP_REASON_TCP_AONOTFOUND,
/**
* @SKB_DROP_REASON_TCP_AOUNEXPECTED: TCP-AO hash is present and it
- * was not expected.
+ * was not expected, corresponding to LINUX_MIB_TCPAOKEYNOTFOUND
*/
SKB_DROP_REASON_TCP_AOUNEXPECTED,
- /** @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown */
+ /**
+ * @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown,
+ * corresponding to LINUX_MIB_TCPAOKEYNOTFOUND
+ */
SKB_DROP_REASON_TCP_AOKEYNOTFOUND,
- /** @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong */
+ /**
+ * @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong,
+ * corresponding to LINUX_MIB_TCPAOBAD
+ */
SKB_DROP_REASON_TCP_AOFAILURE,
/**
* @SKB_DROP_REASON_SOCKET_BACKLOG: failed to add skb to socket backlog (
diff --git a/include/net/tcp.h b/include/net/tcp.h
index c5c7893c77cc..bda549703fd4 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2674,7 +2674,7 @@ static inline int tcp_parse_auth_options(const struct tcphdr *th,
}

static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
- int family)
+ int family, bool stat_inc)
{
#ifdef CONFIG_TCP_AO
struct tcp_ao_info *ao_info;
@@ -2686,8 +2686,13 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
return false;

ao_key = tcp_ao_do_lookup(sk, saddr, family, -1, -1);
- if (ao_info->ao_required || ao_key)
+ if (ao_info->ao_required || ao_key) {
+ if (stat_inc) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOREQUIRED);
+ atomic64_inc(&ao_info->counters.ao_required);
+ }
return true;
+ }
#endif
return false;
}
@@ -2709,8 +2714,10 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
return SKB_DROP_REASON_TCP_AUTH_HDR;

if (req) {
- if (tcp_rsk_used_ao(req) != !!aoh)
+ if (tcp_rsk_used_ao(req) != !!aoh) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
return SKB_DROP_REASON_TCP_AOFAILURE;
+ }
}

/* sdif set, means packet ingressed via a device
@@ -2725,7 +2732,7 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
* the last key is impossible to remove, so there's
* always at least one current_key.
*/
- if (tcp_ao_required(sk, saddr, family))
+ if (tcp_ao_required(sk, saddr, family, true))
return SKB_DROP_REASON_TCP_AONOTFOUND;
if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 6e62235c7cae..b34b9a37c81b 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -19,6 +19,13 @@ struct tcp_ao_hdr {
u8 rnext_keyid;
};

+struct tcp_ao_counters {
+ atomic64_t pkt_good;
+ atomic64_t pkt_bad;
+ atomic64_t key_not_found;
+ atomic64_t ao_required;
+};
+
struct tcp_ao_key {
struct hlist_node node;
union tcp_ao_addr addr;
@@ -33,6 +40,8 @@ struct tcp_ao_key {
u8 rcvid;
u8 maclen;
struct rcu_head rcu;
+ atomic64_t pkt_good;
+ atomic64_t pkt_bad;
u8 traffic_keys[];
};

@@ -81,6 +90,7 @@ struct tcp_ao_info {
*/
struct tcp_ao_key *current_key;
struct tcp_ao_key *rnext_key;
+ struct tcp_ao_counters counters;
u32 ao_required :1,
__unused :31;
__be32 lisn;
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 26f33a4c253d..06ddf4cd295c 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -296,6 +296,10 @@ enum
LINUX_MIB_TCPMIGRATEREQSUCCESS, /* TCPMigrateReqSuccess */
LINUX_MIB_TCPMIGRATEREQFAILURE, /* TCPMigrateReqFailure */
LINUX_MIB_TCPPLBREHASH, /* TCPPLBRehash */
+ LINUX_MIB_TCPAOREQUIRED, /* TCPAORequired */
+ LINUX_MIB_TCPAOBAD, /* TCPAOBad */
+ LINUX_MIB_TCPAOKEYNOTFOUND, /* TCPAOKeyNotFound */
+ LINUX_MIB_TCPAOGOOD, /* TCPAOGood */
__LINUX_MIB_MAX
};

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8285300f95c9..62543f7c5523 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -403,9 +403,15 @@ struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */
__u32 set_current :1, /* corresponding ::current_key */
set_rnext :1, /* corresponding ::rnext */
ao_required :1, /* don't accept non-AO connects */
- reserved :29; /* must be 0 */
+ set_counters :1, /* set/clear ::pkt_* counters */
+ reserved :28; /* must be 0 */
+ __u16 reserved2; /* padding, must be 0 */
__u8 current_key; /* KeyID to set as Current_key */
__u8 rnext; /* KeyID to set as Rnext_key */
+ __u64 pkt_good; /* verified segments */
+ __u64 pkt_bad; /* failed verification */
+ __u64 pkt_key_not_found; /* could not find a key to verify */
+ __u64 pkt_ao_required; /* segments missing TCP-AO sign */
} __attribute__((aligned(8)));

/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index eaf1d3113b62..3f643cd29cfe 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -298,6 +298,10 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPMigrateReqSuccess", LINUX_MIB_TCPMIGRATEREQSUCCESS),
SNMP_MIB_ITEM("TCPMigrateReqFailure", LINUX_MIB_TCPMIGRATEREQFAILURE),
SNMP_MIB_ITEM("TCPPLBRehash", LINUX_MIB_TCPPLBREHASH),
+ SNMP_MIB_ITEM("TCPAORequired", LINUX_MIB_TCPAOREQUIRED),
+ SNMP_MIB_ITEM("TCPAOBad", LINUX_MIB_TCPAOBAD),
+ SNMP_MIB_ITEM("TCPAOKeyNotFound", LINUX_MIB_TCPAOKEYNOTFOUND),
+ SNMP_MIB_ITEM("TCPAOGood", LINUX_MIB_TCPAOGOOD),
SNMP_MIB_SENTINEL
};

diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 4813b9283c55..f7ee2aecf8fc 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -182,6 +182,8 @@ static struct tcp_ao_key *tcp_ao_copy_key(struct sock *sk,
*new_key = *key;
INIT_HLIST_NODE(&new_key->node);
tcp_sigpool_get(new_key->tcp_sigpool_id);
+ atomic64_set(&new_key->pkt_good, 0);
+ atomic64_set(&new_key->pkt_bad, 0);

return new_key;
}
@@ -771,8 +773,12 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
const struct tcphdr *th = tcp_hdr(skb);
void *hash_buf = NULL;

- if (maclen != tcp_ao_maclen(key))
+ if (maclen != tcp_ao_maclen(key)) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
+ atomic64_inc(&info->counters.pkt_bad);
+ atomic64_inc(&key->pkt_bad);
return SKB_DROP_REASON_TCP_AOFAILURE;
+ }

hash_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
if (!hash_buf)
@@ -782,9 +788,15 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
tcp_ao_hash_skb(family, hash_buf, key, sk, skb, traffic_key,
(phash - (u8 *)th), sne);
if (memcmp(phash, hash_buf, maclen)) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
+ atomic64_inc(&info->counters.pkt_bad);
+ atomic64_inc(&key->pkt_bad);
kfree(hash_buf);
return SKB_DROP_REASON_TCP_AOFAILURE;
}
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOGOOD);
+ atomic64_inc(&info->counters.pkt_good);
+ atomic64_inc(&key->pkt_good);
kfree(hash_buf);
return SKB_NOT_DROPPED_YET;
}
@@ -804,8 +816,10 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
u32 sne = 0;

info = rcu_dereference(tcp_sk(sk)->ao_info);
- if (!info)
+ if (!info) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOKEYNOTFOUND);
return SKB_DROP_REASON_TCP_AOUNEXPECTED;
+ }

if (unlikely(th->syn)) {
sisn = th->seq;
@@ -900,6 +914,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
return ret;

key_not_found:
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOKEYNOTFOUND);
+ atomic64_inc(&info->counters.key_not_found);
return SKB_DROP_REASON_TCP_AOKEYNOTFOUND;
}

@@ -1480,6 +1496,8 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
key->keyflags = cmd.keyflags;
key->sndid = cmd.sndid;
key->rcvid = cmd.rcvid;
+ atomic64_set(&key->pkt_good, 0);
+ atomic64_set(&key->pkt_bad, 0);

ret = tcp_ao_parse_crypto(&cmd, key);
if (ret < 0)
@@ -1696,7 +1714,7 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
return -EINVAL;
}

- if (cmd.reserved != 0)
+ if (cmd.reserved != 0 || cmd.reserved2 != 0)
return -EINVAL;

ao_info = setsockopt_ao_info(sk);
@@ -1731,6 +1749,12 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
goto out;
}
}
+ if (cmd.set_counters) {
+ atomic64_set(&ao_info->counters.pkt_good, cmd.pkt_good);
+ atomic64_set(&ao_info->counters.pkt_bad, cmd.pkt_bad);
+ atomic64_set(&ao_info->counters.key_not_found, cmd.pkt_key_not_found);
+ atomic64_set(&ao_info->counters.ao_required, cmd.pkt_ao_required);
+ }

ao_info->ao_required = cmd.ao_required;
if (new_current)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1b1ad6da5929..1e714b26d9ce 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1530,7 +1530,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
/* Don't allow keys for peers that have a matching TCP-AO key.
* See the comment in tcp_ao_add_cmd()
*/
- if (tcp_ao_required(sk, addr, AF_INET))
+ if (tcp_ao_required(sk, addr, AF_INET, false))
return -EKEYREJECTED;

return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index aefe0825532e..d022659f40e8 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -660,7 +660,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
/* Don't allow keys for peers that have a matching TCP-AO key.
* See the comment in tcp_ao_add_cmd()
*/
- if (tcp_ao_required(sk, addr, AF_INET))
+ if (tcp_ao_required(sk, addr, AF_INET, false))
return -EKEYREJECTED;
return tcp_md5_do_add(sk, addr,
AF_INET, prefixlen, l3index, flags,
@@ -672,7 +672,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
/* Don't allow keys for peers that have a matching TCP-AO key.
* See the comment in tcp_ao_add_cmd()
*/
- if (tcp_ao_required(sk, addr, AF_INET6))
+ if (tcp_ao_required(sk, addr, AF_INET6, false))
return -EKEYREJECTED;

return tcp_md5_do_add(sk, addr, AF_INET6, prefixlen, l3index, flags,
--
2.42.0

2023-10-09 23:09:09

by Dmitry Safonov

Subject: [PATCH v14 net-next 06/23] net/tcp: Add TCP-AO sign to outgoing packets

Using precalculated traffic keys, sign TCP segments as prescribed by
RFC5925. Per RFC, TCP header options are included in sign calculation:
"The TCP header, by default including options, and where the TCP
checksum and TCP-AO MAC fields are set to zero, all in network-
byte order." (5.1.3)

tcp_ao_hash_header() has exclude_options parameter to optionally exclude
TCP header from hash calculation, as described in RFC5925 (9.1), this is
needed for interaction with middleboxes that may change "some TCP
options". This is wired up to AO key flags and setsockopt() later.

Similarly to TCP-MD5 hash TCP segment fragments.

From this moment a user can start sending TCP-AO signed segments with
one of crypto ahash algorithms from supported by Linux kernel. It can
have a user-specified MAC length, to either save TCP option header space
or provide higher protection using a longer signature.
The inbound segments are not yet verified, TCP-AO option is ignored and
they are accepted.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp.h | 64 ++++++++++++++
include/net/tcp_ao.h | 23 +++++
net/ipv4/tcp_ao.c | 199 ++++++++++++++++++++++++++++++++++++++++++
net/ipv4/tcp_ipv4.c | 1 +
net/ipv4/tcp_output.c | 112 ++++++++++++++++--------
net/ipv6/tcp_ao.c | 28 ++++++
net/ipv6/tcp_ipv6.c | 2 +
7 files changed, 391 insertions(+), 38 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1a03cbd919a0..6073726d614b 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -185,6 +185,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCPOPT_SACK 5 /* SACK Block */
#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
+#define TCPOPT_AO 29 /* Authentication Option (RFC5925) */
#define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
#define TCPOPT_EXP 254 /* Experimental */
@@ -2162,6 +2163,9 @@ struct tcp_sock_af_ops {
int (*ao_calc_key_sk)(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk,
__be32 sisn, __be32 disn, bool send);
+ int (*calc_ao_hash)(char *location, struct tcp_ao_key *ao,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne);
#endif
};

@@ -2215,6 +2219,66 @@ static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
}
#endif

+struct tcp_key {
+ union {
+ struct tcp_ao_key *ao_key;
+ struct tcp_md5sig_key *md5_key;
+ };
+ enum {
+ TCP_KEY_NONE = 0,
+ TCP_KEY_MD5,
+ TCP_KEY_AO,
+ } type;
+};
+
+static inline void tcp_get_current_key(const struct sock *sk,
+ struct tcp_key *out)
+{
+#if defined(CONFIG_TCP_AO) || defined(CONFIG_TCP_MD5SIG)
+ const struct tcp_sock *tp = tcp_sk(sk);
+#endif
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao;
+
+ ao = rcu_dereference_protected(tp->ao_info, lockdep_sock_is_held(sk));
+ if (ao) {
+ out->ao_key = READ_ONCE(ao->current_key);
+ out->type = TCP_KEY_AO;
+ return;
+ }
+#endif
+#ifdef CONFIG_TCP_MD5SIG
+ if (static_branch_unlikely(&tcp_md5_needed.key) &&
+ rcu_access_pointer(tp->md5sig_info)) {
+ out->md5_key = tp->af_specific->md5_lookup(sk, sk);
+ if (out->md5_key) {
+ out->type = TCP_KEY_MD5;
+ return;
+ }
+ }
+#endif
+ out->type = TCP_KEY_NONE;
+}
+
+static inline bool tcp_key_is_md5(const struct tcp_key *key)
+{
+#ifdef CONFIG_TCP_MD5SIG
+ if (static_branch_unlikely(&tcp_md5_needed.key) &&
+ key->type == TCP_KEY_MD5)
+ return true;
+#endif
+ return false;
+}
+
+static inline bool tcp_key_is_ao(const struct tcp_key *key)
+{
+#ifdef CONFIG_TCP_AO
+ if (key->type == TCP_KEY_AO)
+ return true;
+#endif
+ return false;
+}
+
int tcpv4_offload_init(void);

void tcp_v4_init(void);
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index b021a811511b..0b86bc05d8cf 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -111,6 +111,13 @@ struct tcp6_ao_context {

struct tcp_sigpool;

+int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
+ struct tcp_ao_key *key, struct tcphdr *th,
+ __u8 *hash_location);
+int tcp_ao_hash_skb(unsigned short int family,
+ char *ao_hash, struct tcp_ao_key *key,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne);
int tcp_parse_ao(struct sock *sk, int cmd, unsigned short int family,
sockptr_t optval, int optlen);
int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
@@ -126,12 +133,21 @@ struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
int tcp_v4_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk,
__be32 sisn, __be32 disn, bool send);
+int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne);
/* ipv6 specific functions */
+int tcp_v6_ao_hash_pseudoheader(struct tcp_sigpool *hp,
+ const struct in6_addr *daddr,
+ const struct in6_addr *saddr, int nbytes);
int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk, __be32 sisn,
__be32 disn, bool send);
struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
struct sock *addr_sk, int sndid, int rcvid);
+int tcp_v6_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne);
int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);
void tcp_ao_established(struct sock *sk);
void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb);
@@ -139,6 +155,13 @@ void tcp_ao_connect_init(struct sock *sk);

#else /* CONFIG_TCP_AO */

+static inline int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
+ struct tcp_ao_key *key, struct tcphdr *th,
+ __u8 *hash_location)
+{
+ return 0;
+}
+
static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr, int family, int sndid, int rcvid)
{
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 8e3aa82e649e..6eb9241d14a3 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -262,6 +262,171 @@ static int tcp_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
return -EOPNOTSUPP;
}

+static int tcp_v4_ao_hash_pseudoheader(struct tcp_sigpool *hp,
+ __be32 daddr, __be32 saddr,
+ int nbytes)
+{
+ struct tcp4_pseudohdr *bp;
+ struct scatterlist sg;
+
+ bp = hp->scratch;
+ bp->saddr = saddr;
+ bp->daddr = daddr;
+ bp->pad = 0;
+ bp->protocol = IPPROTO_TCP;
+ bp->len = cpu_to_be16(nbytes);
+
+ sg_init_one(&sg, bp, sizeof(*bp));
+ ahash_request_set_crypt(hp->req, &sg, NULL, sizeof(*bp));
+ return crypto_ahash_update(hp->req);
+}
+
+static int tcp_ao_hash_pseudoheader(unsigned short int family,
+ const struct sock *sk,
+ const struct sk_buff *skb,
+ struct tcp_sigpool *hp, int nbytes)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+
+ /* TODO: Can we rely on checksum being zero to mean outbound pkt? */
+ if (!th->check) {
+ if (family == AF_INET)
+ return tcp_v4_ao_hash_pseudoheader(hp, sk->sk_daddr,
+ sk->sk_rcv_saddr, skb->len);
+#if IS_ENABLED(CONFIG_IPV6)
+ else if (family == AF_INET6)
+ return tcp_v6_ao_hash_pseudoheader(hp, &sk->sk_v6_daddr,
+ &sk->sk_v6_rcv_saddr, skb->len);
+#endif
+ else
+ return -EAFNOSUPPORT;
+ }
+
+ if (family == AF_INET) {
+ const struct iphdr *iph = ip_hdr(skb);
+
+ return tcp_v4_ao_hash_pseudoheader(hp, iph->daddr,
+ iph->saddr, skb->len);
+#if IS_ENABLED(CONFIG_IPV6)
+ } else if (family == AF_INET6) {
+ const struct ipv6hdr *iph = ipv6_hdr(skb);
+
+ return tcp_v6_ao_hash_pseudoheader(hp, &iph->daddr,
+ &iph->saddr, skb->len);
+#endif
+ }
+ return -EAFNOSUPPORT;
+}
+
+/* tcp_ao_hash_sne(struct tcp_sigpool *hp)
+ * @hp - used for hashing
+ * @sne - sne value
+ */
+static int tcp_ao_hash_sne(struct tcp_sigpool *hp, u32 sne)
+{
+ struct scatterlist sg;
+ __be32 *bp;
+
+ bp = (__be32 *)hp->scratch;
+ *bp = htonl(sne);
+
+ sg_init_one(&sg, bp, sizeof(*bp));
+ ahash_request_set_crypt(hp->req, &sg, NULL, sizeof(*bp));
+ return crypto_ahash_update(hp->req);
+}
+
+static int tcp_ao_hash_header(struct tcp_sigpool *hp,
+ const struct tcphdr *th,
+ bool exclude_options, u8 *hash,
+ int hash_offset, int hash_len)
+{
+ int err, len = th->doff << 2;
+ struct scatterlist sg;
+ u8 *hdr = hp->scratch;
+
+ /* We are not allowed to change tcphdr, make a local copy */
+ if (exclude_options) {
+ len = sizeof(*th) + sizeof(struct tcp_ao_hdr) + hash_len;
+ memcpy(hdr, th, sizeof(*th));
+ memcpy(hdr + sizeof(*th),
+ (u8 *)th + hash_offset - sizeof(struct tcp_ao_hdr),
+ sizeof(struct tcp_ao_hdr));
+ memset(hdr + sizeof(*th) + sizeof(struct tcp_ao_hdr),
+ 0, hash_len);
+ ((struct tcphdr *)hdr)->check = 0;
+ } else {
+ len = th->doff << 2;
+ memcpy(hdr, th, len);
+ /* zero out tcp-ao hash */
+ ((struct tcphdr *)hdr)->check = 0;
+ memset(hdr + hash_offset, 0, hash_len);
+ }
+
+ sg_init_one(&sg, hdr, len);
+ ahash_request_set_crypt(hp->req, &sg, NULL, len);
+ err = crypto_ahash_update(hp->req);
+ WARN_ON_ONCE(err != 0);
+ return err;
+}
+
+int tcp_ao_hash_skb(unsigned short int family,
+ char *ao_hash, struct tcp_ao_key *key,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ int tkey_len = tcp_ao_digest_size(key);
+ struct tcp_sigpool hp;
+ void *hash_buf = NULL;
+
+ hash_buf = kmalloc(tkey_len, GFP_ATOMIC);
+ if (!hash_buf)
+ goto clear_hash_noput;
+
+ if (tcp_sigpool_start(key->tcp_sigpool_id, &hp))
+ goto clear_hash_noput;
+
+ if (crypto_ahash_setkey(crypto_ahash_reqtfm(hp.req), tkey, tkey_len))
+ goto clear_hash;
+
+ /* For now use sha1 by default. Depends on alg in tcp_ao_key */
+ if (crypto_ahash_init(hp.req))
+ goto clear_hash;
+
+ if (tcp_ao_hash_sne(&hp, sne))
+ goto clear_hash;
+ if (tcp_ao_hash_pseudoheader(family, sk, skb, &hp, skb->len))
+ goto clear_hash;
+ if (tcp_ao_hash_header(&hp, th, false,
+ ao_hash, hash_offset, tcp_ao_maclen(key)))
+ goto clear_hash;
+ if (tcp_sigpool_hash_skb_data(&hp, skb, th->doff << 2))
+ goto clear_hash;
+ ahash_request_set_crypt(hp.req, NULL, hash_buf, 0);
+ if (crypto_ahash_final(hp.req))
+ goto clear_hash;
+
+ memcpy(ao_hash, hash_buf, tcp_ao_maclen(key));
+ tcp_sigpool_end(&hp);
+ kfree(hash_buf);
+ return 0;
+
+clear_hash:
+ tcp_sigpool_end(&hp);
+clear_hash_noput:
+ memset(ao_hash, 0, tcp_ao_maclen(key));
+ kfree(hash_buf);
+ return 1;
+}
+
+int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne)
+{
+ return tcp_ao_hash_skb(AF_INET, ao_hash, key, sk, skb,
+ tkey, hash_offset, sne);
+}
+
struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
int sndid, int rcvid)
{
@@ -270,6 +435,40 @@ struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
return tcp_ao_do_lookup(sk, addr, AF_INET, sndid, rcvid);
}

+int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
+ struct tcp_ao_key *key, struct tcphdr *th,
+ __u8 *hash_location)
+{
+ struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_ao_info *ao;
+ void *tkey_buf = NULL;
+ u8 *traffic_key;
+
+ ao = rcu_dereference_protected(tcp_sk(sk)->ao_info,
+ lockdep_sock_is_held(sk));
+ traffic_key = snd_other_key(key);
+ if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) {
+ __be32 disn;
+
+ if (!(tcb->tcp_flags & TCPHDR_ACK)) {
+ disn = 0;
+ tkey_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
+ if (!tkey_buf)
+ return -ENOMEM;
+ traffic_key = tkey_buf;
+ } else {
+ disn = ao->risn;
+ }
+ tp->af_specific->ao_calc_key_sk(key, traffic_key,
+ sk, ao->lisn, disn, true);
+ }
+ tp->af_specific->calc_ao_hash(hash_location, key, sk, skb, traffic_key,
+ hash_location - (u8 *)th, 0);
+ kfree(tkey_buf);
+ return 0;
+}
+
static int tcp_ao_cache_traffic_keys(const struct sock *sk,
struct tcp_ao_info *ao,
struct tcp_ao_key *ao_key)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b77cbe1047b3..f357538140f6 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2285,6 +2285,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
#endif
#ifdef CONFIG_TCP_AO
.ao_lookup = tcp_v4_ao_lookup,
+ .calc_ao_hash = tcp_v4_ao_hash_skb,
.ao_parse = tcp_v4_parse_ao,
.ao_calc_key_sk = tcp_v4_ao_calc_key_sk,
#endif
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4ebab9c8ad33..23fce35a6f65 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -422,6 +422,7 @@ static inline bool tcp_urg_mode(const struct tcp_sock *tp)
#define OPTION_FAST_OPEN_COOKIE BIT(8)
#define OPTION_SMC BIT(9)
#define OPTION_MPTCP BIT(10)
+#define OPTION_AO BIT(11)

static void smc_options_write(__be32 *ptr, u16 *options)
{
@@ -614,19 +615,43 @@ static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb,
* (but it may well be that other scenarios fail similarly).
*/
static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp,
- struct tcp_out_options *opts)
+ struct tcp_out_options *opts,
+ struct tcp_key *key)
{
__be32 *ptr = (__be32 *)(th + 1);
u16 options = opts->options; /* mungable copy */

- if (unlikely(OPTION_MD5 & options)) {
+ if (tcp_key_is_md5(key)) {
*ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
(TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
/* overload cookie hash location */
opts->hash_location = (__u8 *)ptr;
ptr += 4;
- }
+ } else if (tcp_key_is_ao(key)) {
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_key *rnext_key;
+ struct tcp_ao_info *ao_info;
+ u8 maclen;

+ ao_info = rcu_dereference_check(tp->ao_info,
+ lockdep_sock_is_held(&tp->inet_conn.icsk_inet.sk));
+ rnext_key = READ_ONCE(ao_info->rnext_key);
+ if (WARN_ON_ONCE(!rnext_key))
+ goto out_ao;
+ maclen = tcp_ao_maclen(key->ao_key);
+ *ptr++ = htonl((TCPOPT_AO << 24) |
+ (tcp_ao_len(key->ao_key) << 16) |
+ (key->ao_key->sndid << 8) |
+ (rnext_key->rcvid));
+ opts->hash_location = (__u8 *)ptr;
+ ptr += maclen / sizeof(*ptr);
+ if (unlikely(maclen % sizeof(*ptr))) {
+ memset(ptr, TCPOPT_NOP, sizeof(*ptr));
+ ptr++;
+ }
+out_ao:
+#endif
+ }
if (unlikely(opts->mss)) {
*ptr++ = htonl((TCPOPT_MSS << 24) |
(TCPOLEN_MSS << 16) |
@@ -767,23 +792,25 @@ static void mptcp_set_option_cond(const struct request_sock *req,
*/
static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
struct tcp_out_options *opts,
- struct tcp_md5sig_key **md5)
+ struct tcp_key *key)
{
struct tcp_sock *tp = tcp_sk(sk);
unsigned int remaining = MAX_TCP_OPTION_SPACE;
struct tcp_fastopen_request *fastopen = tp->fastopen_req;
+ bool timestamps;

- *md5 = NULL;
-#ifdef CONFIG_TCP_MD5SIG
- if (static_branch_unlikely(&tcp_md5_needed.key) &&
- rcu_access_pointer(tp->md5sig_info)) {
- *md5 = tp->af_specific->md5_lookup(sk, sk);
- if (*md5) {
- opts->options |= OPTION_MD5;
- remaining -= TCPOLEN_MD5SIG_ALIGNED;
+ /* Better than switch (key.type) as it has static branches */
+ if (tcp_key_is_md5(key)) {
+ timestamps = false;
+ opts->options |= OPTION_MD5;
+ remaining -= TCPOLEN_MD5SIG_ALIGNED;
+ } else {
+ timestamps = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps);
+ if (tcp_key_is_ao(key)) {
+ opts->options |= OPTION_AO;
+ remaining -= tcp_ao_len(key->ao_key);
}
}
-#endif

/* We always get an MSS option. The option bytes which will be seen in
* normal data packets should timestamps be used, must be in the MSS
@@ -797,7 +824,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
opts->mss = tcp_advertise_mss(sk);
remaining -= TCPOLEN_MSS_ALIGNED;

- if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps) && !*md5)) {
+ if (likely(timestamps)) {
opts->options |= OPTION_TS;
opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset;
opts->tsecr = tp->rx_opt.ts_recent;
@@ -921,7 +948,7 @@ static unsigned int tcp_synack_options(const struct sock *sk,
*/
static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb,
struct tcp_out_options *opts,
- struct tcp_md5sig_key **md5)
+ struct tcp_key *key)
{
struct tcp_sock *tp = tcp_sk(sk);
unsigned int size = 0;
@@ -929,17 +956,14 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb

opts->options = 0;

- *md5 = NULL;
-#ifdef CONFIG_TCP_MD5SIG
- if (static_branch_unlikely(&tcp_md5_needed.key) &&
- rcu_access_pointer(tp->md5sig_info)) {
- *md5 = tp->af_specific->md5_lookup(sk, sk);
- if (*md5) {
- opts->options |= OPTION_MD5;
- size += TCPOLEN_MD5SIG_ALIGNED;
- }
+ /* Better than switch (key.type) as it has static branches */
+ if (tcp_key_is_md5(key)) {
+ opts->options |= OPTION_MD5;
+ size += TCPOLEN_MD5SIG_ALIGNED;
+ } else if (tcp_key_is_ao(key)) {
+ opts->options |= OPTION_AO;
+ size += tcp_ao_len(key->ao_key);
}
-#endif

if (likely(tp->rx_opt.tstamp_ok)) {
opts->options |= OPTION_TS;
@@ -1243,7 +1267,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
struct tcp_out_options opts;
unsigned int tcp_options_size, tcp_header_size;
struct sk_buff *oskb = NULL;
- struct tcp_md5sig_key *md5;
+ struct tcp_key key;
struct tcphdr *th;
u64 prior_wstamp;
int err;
@@ -1275,11 +1299,11 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
tcb = TCP_SKB_CB(skb);
memset(&opts, 0, sizeof(opts));

+ tcp_get_current_key(sk, &key);
if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) {
- tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5);
+ tcp_options_size = tcp_syn_options(sk, skb, &opts, &key);
} else {
- tcp_options_size = tcp_established_options(sk, skb, &opts,
- &md5);
+ tcp_options_size = tcp_established_options(sk, skb, &opts, &key);
/* Force a PSH flag on all (GSO) packets to expedite GRO flush
* at receiver : This slightly improve GRO performance.
* Note that we do not force the PSH flag for non GSO packets,
@@ -1360,16 +1384,25 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
th->window = htons(min(tp->rcv_wnd, 65535U));
}

- tcp_options_write(th, tp, &opts);
+ tcp_options_write(th, tp, &opts, &key);

+ if (tcp_key_is_md5(&key)) {
#ifdef CONFIG_TCP_MD5SIG
- /* Calculate the MD5 hash, as we have all we need now */
- if (md5) {
+ /* Calculate the MD5 hash, as we have all we need now */
sk_gso_disable(sk);
tp->af_specific->calc_md5_hash(opts.hash_location,
- md5, sk, skb);
- }
+ key.md5_key, sk, skb);
#endif
+ } else if (tcp_key_is_ao(&key)) {
+ int err;
+
+ err = tcp_ao_transmit_skb(sk, skb, key.ao_key, th,
+ opts.hash_location);
+ if (err) {
+ kfree_skb_reason(skb, SKB_DROP_REASON_NOT_SPECIFIED);
+ return -ENOMEM;
+ }
+ }

/* BPF prog is the last one writing header option */
bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts);
@@ -1820,7 +1853,7 @@ unsigned int tcp_current_mss(struct sock *sk)
u32 mss_now;
unsigned int header_len;
struct tcp_out_options opts;
- struct tcp_md5sig_key *md5;
+ struct tcp_key key;

mss_now = tp->mss_cache;

@@ -1829,8 +1862,8 @@ unsigned int tcp_current_mss(struct sock *sk)
if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
mss_now = tcp_sync_mss(sk, mtu);
}
-
- header_len = tcp_established_options(sk, NULL, &opts, &md5) +
+ tcp_get_current_key(sk, &key);
+ header_len = tcp_established_options(sk, NULL, &opts, &key) +
sizeof(struct tcphdr);
/* The mss_cache is sized based on tp->tcp_header_len, which assumes
* some common options. If this is an odd packet (because we have SACK
@@ -3615,6 +3648,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
const struct tcp_sock *tp = tcp_sk(sk);
struct tcp_md5sig_key *md5 = NULL;
struct tcp_out_options opts;
+ struct tcp_key key = {};
struct sk_buff *skb;
int tcp_header_size;
struct tcphdr *th;
@@ -3667,6 +3701,8 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
#ifdef CONFIG_TCP_MD5SIG
rcu_read_lock();
md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req));
+ if (md5)
+ key.type = TCP_KEY_MD5;
#endif
skb_set_hash(skb, READ_ONCE(tcp_rsk(req)->txhash), PKT_HASH_TYPE_L4);
/* bpf program will be interested in the tcp_flags */
@@ -3693,7 +3729,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,

/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
th->window = htons(min(req->rsk_rcv_wnd, 65535U));
- tcp_options_write(th, NULL, &opts);
+ tcp_options_write(th, NULL, &opts, &key);
th->doff = (tcp_header_size >> 2);
TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS);

diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c
index 9ab594fadbd9..d08735b6f3c5 100644
--- a/net/ipv6/tcp_ao.c
+++ b/net/ipv6/tcp_ao.c
@@ -7,6 +7,7 @@
* Francesco Ruggeri <[email protected]>
* Salam Noureddine <[email protected]>
*/
+#include <crypto/hash.h>
#include <linux/tcp.h>

#include <net/tcp.h>
@@ -79,6 +80,33 @@ struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid);
}

+int tcp_v6_ao_hash_pseudoheader(struct tcp_sigpool *hp,
+ const struct in6_addr *daddr,
+ const struct in6_addr *saddr, int nbytes)
+{
+ struct tcp6_pseudohdr *bp;
+ struct scatterlist sg;
+
+ bp = hp->scratch;
+ /* 1. TCP pseudo-header (RFC2460) */
+ bp->saddr = *saddr;
+ bp->daddr = *daddr;
+ bp->len = cpu_to_be32(nbytes);
+ bp->protocol = cpu_to_be32(IPPROTO_TCP);
+
+ sg_init_one(&sg, bp, sizeof(*bp));
+ ahash_request_set_crypt(hp->req, &sg, NULL, sizeof(*bp));
+ return crypto_ahash_update(hp->req);
+}
+
+int tcp_v6_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
+ const struct sock *sk, const struct sk_buff *skb,
+ const u8 *tkey, int hash_offset, u32 sne)
+{
+ return tcp_ao_hash_skb(AF_INET6, ao_hash, key, sk, skb, tkey,
+ hash_offset, sne);
+}
+
int tcp_v6_parse_ao(struct sock *sk, int cmd,
sockptr_t optval, int optlen)
{
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 645fe82866c6..c7834d23a8dc 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1920,6 +1920,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_specific = {
#endif
#ifdef CONFIG_TCP_AO
.ao_lookup = tcp_v6_ao_lookup,
+ .calc_ao_hash = tcp_v6_ao_hash_skb,
.ao_parse = tcp_v6_parse_ao,
.ao_calc_key_sk = tcp_v6_ao_calc_key_sk,
#endif
@@ -1953,6 +1954,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = {
#endif
#ifdef CONFIG_TCP_AO
.ao_lookup = tcp_v6_ao_lookup,
+ .calc_ao_hash = tcp_v4_ao_hash_skb,
.ao_parse = tcp_v6_parse_ao,
#endif
};
--
2.42.0

2023-10-09 23:09:09

by Dmitry Safonov

Subject: [PATCH v14 net-next 10/23] net/tcp: Wire TCP-AO to request sockets

Now when the new request socket is created from the listening socket,
it's recorded what MKT was used by the peer. tcp_rsk_used_ao() is
a new helper for checking if TCP-AO option was used to create the
request socket.
tcp_ao_copy_all_matching() will copy all keys that match the peer on the
request socket, as well as preparing them for the usage (creating
traffic keys).

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/linux/tcp.h | 18 +++
include/net/tcp.h | 6 +
include/net/tcp_ao.h | 24 ++++
net/ipv4/syncookies.c | 2 +
net/ipv4/tcp_ao.c | 237 ++++++++++++++++++++++++++++++++++++++-
net/ipv4/tcp_input.c | 15 +++
net/ipv4/tcp_ipv4.c | 66 +++++++++--
net/ipv4/tcp_minisocks.c | 10 ++
net/ipv4/tcp_output.c | 37 +++---
net/ipv6/syncookies.c | 2 +
net/ipv6/tcp_ao.c | 38 ++++++-
net/ipv6/tcp_ipv6.c | 73 ++++++++++--
12 files changed, 491 insertions(+), 37 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 51458219be4e..1d9b8e04a4ee 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -165,6 +165,11 @@ struct tcp_request_sock {
* after data-in-SYN.
*/
u8 syn_tos;
+#ifdef CONFIG_TCP_AO
+ u8 ao_keyid;
+ u8 ao_rcv_next;
+ u8 maclen;
+#endif
};

static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
@@ -172,6 +177,19 @@ static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
return (struct tcp_request_sock *)req;
}

+static inline bool tcp_rsk_used_ao(const struct request_sock *req)
+{
+ /* The real length of MAC is saved in the request socket,
+ * signing anything with zero-length makes no sense, so here is
+ * a little hack..
+ */
+#ifndef CONFIG_TCP_AO
+ return false;
+#else
+ return tcp_rsk(req)->maclen != 0;
+#endif
+}
+
#define TCP_RMEM_TO_WIN_SCALE 8

struct tcp_sock {
diff --git a/include/net/tcp.h b/include/net/tcp.h
index dc74908ffa5a..13657b70d5d7 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2178,6 +2178,12 @@ struct tcp_request_sock_ops {
const struct sock *sk,
const struct sk_buff *skb);
#endif
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_key *(*ao_lookup)(const struct sock *sk,
+ struct request_sock *req,
+ int sndid, int rcvid);
+ int (*ao_calc_key)(struct tcp_ao_key *mkt, u8 *key, struct request_sock *sk);
+#endif
#ifdef CONFIG_SYN_COOKIES
__u32 (*cookie_init_seq)(const struct sk_buff *skb,
__u16 *mss);
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index af2caf7e76fc..d04b17971c3c 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -123,6 +123,9 @@ int tcp_parse_ao(struct sock *sk, int cmd, unsigned short int family,
sockptr_t optval, int optlen);
struct tcp_ao_key *tcp_ao_established_key(struct tcp_ao_info *ao,
int sndid, int rcvid);
+int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk,
+ struct request_sock *req, struct sk_buff *skb,
+ int family);
int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp);
void tcp_ao_destroy_sock(struct sock *sk, bool twsk);
@@ -147,6 +150,11 @@ struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
int tcp_v4_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk,
__be32 sisn, __be32 disn, bool send);
+int tcp_v4_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
+ struct request_sock *req);
+struct tcp_ao_key *tcp_v4_ao_lookup_rsk(const struct sock *sk,
+ struct request_sock *req,
+ int sndid, int rcvid);
int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
const struct sock *sk, const struct sk_buff *skb,
const u8 *tkey, int hash_offset, u32 sne);
@@ -154,11 +162,21 @@ int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
int tcp_v6_ao_hash_pseudoheader(struct tcp_sigpool *hp,
const struct in6_addr *daddr,
const struct in6_addr *saddr, int nbytes);
+int tcp_v6_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
+ const struct sk_buff *skb, __be32 sisn, __be32 disn);
int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk, __be32 sisn,
__be32 disn, bool send);
+int tcp_v6_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
+ struct request_sock *req);
+struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk,
+ const struct in6_addr *addr,
+ int sndid, int rcvid);
struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
struct sock *addr_sk, int sndid, int rcvid);
+struct tcp_ao_key *tcp_v6_ao_lookup_rsk(const struct sock *sk,
+ struct request_sock *req,
+ int sndid, int rcvid);
int tcp_v6_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
const struct sock *sk, const struct sk_buff *skb,
const u8 *tkey, int hash_offset, u32 sne);
@@ -178,6 +196,12 @@ static inline int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
return 0;
}

+static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
+ struct tcp_request_sock *treq,
+ unsigned short int family)
+{
+}
+
static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr, int family, int sndid, int rcvid)
{
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index dc478a0574cb..23fca22bc992 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -394,6 +394,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
treq->snt_synack = 0;
treq->tfo_listener = false;

+ tcp_ao_syncookie(sk, skb, treq, AF_INET);
+
if (IS_ENABLED(CONFIG_SMC))
ireq->smc_ok = 0;

diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 00d21f6242de..c8006b0cbb8a 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -169,6 +169,23 @@ static void tcp_ao_link_mkt(struct tcp_ao_info *ao, struct tcp_ao_key *mkt)
hlist_add_head_rcu(&mkt->node, &ao->head);
}

+static struct tcp_ao_key *tcp_ao_copy_key(struct sock *sk,
+ struct tcp_ao_key *key)
+{
+ struct tcp_ao_key *new_key;
+
+ new_key = sock_kmalloc(sk, tcp_ao_sizeof_key(key),
+ GFP_ATOMIC);
+ if (!new_key)
+ return NULL;
+
+ *new_key = *key;
+ INIT_HLIST_NODE(&new_key->node);
+ tcp_sigpool_get(new_key->tcp_sigpool_id);
+
+ return new_key;
+}
+
static void tcp_ao_key_free_rcu(struct rcu_head *head)
{
struct tcp_ao_key *key = container_of(head, struct tcp_ao_key, rcu);
@@ -290,6 +307,42 @@ static int tcp_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
return -EOPNOTSUPP;
}

+int tcp_v4_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
+ struct request_sock *req)
+{
+ struct inet_request_sock *ireq = inet_rsk(req);
+
+ return tcp_v4_ao_calc_key(mkt, key,
+ ireq->ir_loc_addr, ireq->ir_rmt_addr,
+ htons(ireq->ir_num), ireq->ir_rmt_port,
+ htonl(tcp_rsk(req)->snt_isn),
+ htonl(tcp_rsk(req)->rcv_isn));
+}
+
+static int tcp_v4_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
+ const struct sk_buff *skb,
+ __be32 sisn, __be32 disn)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ const struct tcphdr *th = tcp_hdr(skb);
+
+ return tcp_v4_ao_calc_key(mkt, key, iph->saddr, iph->daddr,
+ th->source, th->dest, sisn, disn);
+}
+
+static int tcp_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
+ const struct sk_buff *skb,
+ __be32 sisn, __be32 disn, int family)
+{
+ if (family == AF_INET)
+ return tcp_v4_ao_calc_key_skb(mkt, key, skb, sisn, disn);
+#if IS_ENABLED(CONFIG_IPV6)
+ else if (family == AF_INET6)
+ return tcp_v6_ao_calc_key_skb(mkt, key, skb, sisn, disn);
+#endif
+ return -EAFNOSUPPORT;
+}
+
static int tcp_v4_ao_hash_pseudoheader(struct tcp_sigpool *hp,
__be32 daddr, __be32 saddr,
int nbytes)
@@ -515,6 +568,16 @@ int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
tkey, hash_offset, sne);
}

+struct tcp_ao_key *tcp_v4_ao_lookup_rsk(const struct sock *sk,
+ struct request_sock *req,
+ int sndid, int rcvid)
+{
+ union tcp_ao_addr *addr =
+ (union tcp_ao_addr *)&inet_rsk(req)->ir_rmt_addr;
+
+ return tcp_ao_do_lookup(sk, addr, AF_INET, sndid, rcvid);
+}
+
struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
int sndid, int rcvid)
{
@@ -528,6 +591,7 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
struct tcp_ao_key **key, char **traffic_key,
bool *allocated_traffic_key, u8 *keyid, u32 *sne)
{
+ const struct tcphdr *th = tcp_hdr(skb);
struct tcp_ao_info *ao_info;

*allocated_traffic_key = false;
@@ -542,7 +606,44 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
return -ENOTCONN;

if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
- return -1;
+ union tcp_ao_addr *addr;
+ unsigned int family = READ_ONCE(sk->sk_family);
+ __be32 disn, sisn;
+
+ if (sk->sk_state == TCP_NEW_SYN_RECV) {
+ struct request_sock *req = inet_reqsk(sk);
+
+ sisn = htonl(tcp_rsk(req)->rcv_isn);
+ disn = htonl(tcp_rsk(req)->snt_isn);
+ *sne = 0;
+ } else {
+ sisn = th->seq;
+ disn = 0;
+ }
+ if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6)
+ addr = (union tcp_md5_addr *)&ipv6_hdr(skb)->saddr;
+ else
+ addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
+#if IS_ENABLED(CONFIG_IPV6)
+ if (family == AF_INET6 && ipv6_addr_v4mapped(&sk->sk_v6_daddr))
+ family = AF_INET;
+#endif
+
+ sk = sk_const_to_full_sk(sk);
+ ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
+ if (!ao_info)
+ return -ENOENT;
+ *key = tcp_ao_do_lookup(sk, addr, family, -1, aoh->rnext_keyid);
+ if (!*key)
+ return -ENOENT;
+ *traffic_key = kmalloc(tcp_ao_digest_size(*key), GFP_ATOMIC);
+ if (!*traffic_key)
+ return -ENOMEM;
+ *allocated_traffic_key = true;
+ if (tcp_ao_calc_key_skb(*key, *traffic_key, skb,
+ sisn, disn, family))
+ return -1;
+ *keyid = (*key)->rcvid;
} else {
struct tcp_ao_key *rnext_key;

@@ -598,6 +699,46 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
return 0;
}

+static struct tcp_ao_key *tcp_ao_inbound_lookup(unsigned short int family,
+ const struct sock *sk, const struct sk_buff *skb,
+ int sndid, int rcvid)
+{
+ if (family == AF_INET) {
+ const struct iphdr *iph = ip_hdr(skb);
+
+ return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)&iph->saddr,
+ AF_INET, sndid, rcvid);
+ } else {
+ const struct ipv6hdr *iph = ipv6_hdr(skb);
+
+ return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)&iph->saddr,
+ AF_INET6, sndid, rcvid);
+ }
+}
+
+void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
+ struct tcp_request_sock *treq,
+ unsigned short int family)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ const struct tcp_ao_hdr *aoh;
+ struct tcp_ao_key *key;
+
+ treq->maclen = 0;
+
+ if (tcp_parse_auth_options(th, NULL, &aoh) || !aoh)
+ return;
+
+ key = tcp_ao_inbound_lookup(family, sk, skb, -1, aoh->keyid);
+ if (!key)
+ /* Key not found, continue without TCP-AO */
+ return;
+
+ treq->ao_rcv_next = aoh->keyid;
+ treq->ao_keyid = aoh->rnext_keyid;
+ treq->maclen = tcp_ao_maclen(key);
+}
+
static int tcp_ao_cache_traffic_keys(const struct sock *sk,
struct tcp_ao_info *ao,
struct tcp_ao_key *ao_key)
@@ -702,6 +843,100 @@ void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb)
tcp_ao_cache_traffic_keys(sk, ao, key);
}

+int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk,
+ struct request_sock *req, struct sk_buff *skb,
+ int family)
+{
+ struct tcp_ao_key *key, *new_key, *first_key;
+ struct tcp_ao_info *new_ao, *ao;
+ struct hlist_node *key_head;
+ union tcp_ao_addr *addr;
+ bool match = false;
+ int ret = -ENOMEM;
+
+ ao = rcu_dereference(tcp_sk(sk)->ao_info);
+ if (!ao)
+ return 0;
+
+ /* New socket without TCP-AO on it */
+ if (!tcp_rsk_used_ao(req))
+ return 0;
+
+ new_ao = tcp_ao_alloc_info(GFP_ATOMIC);
+ if (!new_ao)
+ return -ENOMEM;
+ new_ao->lisn = htonl(tcp_rsk(req)->snt_isn);
+ new_ao->risn = htonl(tcp_rsk(req)->rcv_isn);
+ new_ao->ao_required = ao->ao_required;
+
+ if (family == AF_INET) {
+ addr = (union tcp_ao_addr *)&newsk->sk_daddr;
+#if IS_ENABLED(CONFIG_IPV6)
+ } else if (family == AF_INET6) {
+ addr = (union tcp_ao_addr *)&newsk->sk_v6_daddr;
+#endif
+ } else {
+ ret = -EAFNOSUPPORT;
+ goto free_ao;
+ }
+
+ hlist_for_each_entry_rcu(key, &ao->head, node) {
+ if (tcp_ao_key_cmp(key, addr, key->prefixlen, family, -1, -1))
+ continue;
+
+ new_key = tcp_ao_copy_key(newsk, key);
+ if (!new_key)
+ goto free_and_exit;
+
+ tcp_ao_cache_traffic_keys(newsk, new_ao, new_key);
+ tcp_ao_link_mkt(new_ao, new_key);
+ match = true;
+ }
+
+ if (!match) {
+ /* RFC5925 (7.4.1) specifies that the TCP-AO status
+ * of a connection is determined on the initial SYN.
+ * At this point the connection was TCP-AO enabled, so
+ * it can't switch to being unsigned if peer's key
+ * disappears on the listening socket.
+ */
+ ret = -EKEYREJECTED;
+ goto free_and_exit;
+ }
+
+ key_head = rcu_dereference(hlist_first_rcu(&new_ao->head));
+ first_key = hlist_entry_safe(key_head, struct tcp_ao_key, node);
+
+ key = tcp_ao_established_key(new_ao, tcp_rsk(req)->ao_keyid, -1);
+ if (key)
+ new_ao->current_key = key;
+ else
+ new_ao->current_key = first_key;
+
+ /* set rnext_key */
+ key = tcp_ao_established_key(new_ao, -1, tcp_rsk(req)->ao_rcv_next);
+ if (key)
+ new_ao->rnext_key = key;
+ else
+ new_ao->rnext_key = first_key;
+
+ sk_gso_disable(newsk);
+ rcu_assign_pointer(tcp_sk(newsk)->ao_info, new_ao);
+
+ return 0;
+
+free_and_exit:
+ hlist_for_each_entry_safe(key, key_head, &new_ao->head, node) {
+ hlist_del(&key->node);
+ tcp_sigpool_release(key->tcp_sigpool_id);
+ atomic_sub(tcp_ao_sizeof_key(key), &newsk->sk_omem_alloc);
+ kfree_sensitive(key);
+ }
+free_ao:
+ kfree(new_ao);
+ return ret;
+}
+
static bool tcp_ao_can_set_current_rnext(struct sock *sk)
{
/* There aren't current/rnext keys on TCP_LISTEN sockets */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 5407ef0c1c04..520776714591 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -7016,6 +7016,10 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
struct flowi fl;
u8 syncookies;

+#ifdef CONFIG_TCP_AO
+ const struct tcp_ao_hdr *aoh;
+#endif
+
syncookies = READ_ONCE(net->ipv4.sysctl_tcp_syncookies);

/* TW buckets are converted to open requests without
@@ -7101,6 +7105,17 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
inet_rsk(req)->ecn_ok = 0;
}

+#ifdef CONFIG_TCP_AO
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
+ goto drop_and_release; /* Invalid TCP options */
+ if (aoh) {
+ tcp_rsk(req)->maclen = aoh->length - sizeof(struct tcp_ao_hdr);
+ tcp_rsk(req)->ao_rcv_next = aoh->keyid;
+ tcp_rsk(req)->ao_keyid = aoh->rnext_keyid;
+ } else {
+ tcp_rsk(req)->maclen = 0;
+ }
+#endif
tcp_rsk(req)->snt_isn = isn;
tcp_rsk(req)->txhash = net_tx_rndhash();
tcp_rsk(req)->syn_tos = TCP_SKB_CB(skb)->ip_dsfield;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d98a943a4206..c332a86c22c5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1071,13 +1071,47 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
u32 seq = (sk->sk_state == TCP_LISTEN) ? tcp_rsk(req)->snt_isn + 1 :
tcp_sk(sk)->snd_nxt;

- /* RFC 7323 2.3
- * The window field (SEG.WND) of every outgoing segment, with the
- * exception of <SYN> segments, MUST be right-shifted by
- * Rcv.Wind.Shift bits:
- */
+#ifdef CONFIG_TCP_AO
+ if (tcp_rsk_used_ao(req)) {
+ const union tcp_md5_addr *addr;
+ const struct tcp_ao_hdr *aoh;
+
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
+ return;
+ if (!aoh)
+ return;
+
+ addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
+ key.ao_key = tcp_ao_do_lookup(sk, addr, AF_INET,
+ aoh->rnext_keyid, -1);
+ if (unlikely(!key.ao_key)) {
+ /* Send ACK with any matching MKT for the peer */
+ key.ao_key = tcp_ao_do_lookup(sk, addr, AF_INET, -1, -1);
+ /* Matching key disappeared (user removed the key?)
+ * let the handshake timeout.
+ */
+ if (!key.ao_key) {
+ net_info_ratelimited("TCP-AO key for (%pI4, %d)->(%pI4, %d) suddenly disappeared, won't ACK new connection\n",
+ addr,
+ ntohs(tcp_hdr(skb)->source),
+ &ip_hdr(skb)->daddr,
+ ntohs(tcp_hdr(skb)->dest));
+ return;
+ }
+ }
+ key.traffic_key = kmalloc(tcp_ao_digest_size(key.ao_key), GFP_ATOMIC);
+ if (!key.traffic_key)
+ return;
+
+ key.type = TCP_KEY_AO;
+ key.rcv_next = aoh->keyid;
+ tcp_v4_ao_calc_key_rsk(key.ao_key, key.traffic_key, req);
+#else
+ if (0) {
+#endif
#ifdef CONFIG_TCP_MD5SIG
- if (static_branch_unlikely(&tcp_md5_needed.key)) {
+ } else if (static_branch_unlikely(&tcp_md5_needed.key)) {
const union tcp_md5_addr *addr;
int l3index;

@@ -1086,8 +1120,14 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
key.md5_key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
if (key.md5_key)
key.type = TCP_KEY_MD5;
- }
#endif
+ }
+
+ /* RFC 7323 2.3
+ * The window field (SEG.WND) of every outgoing segment, with the
+ * exception of <SYN> segments, MUST be right-shifted by
+ * Rcv.Wind.Shift bits:
+ */
tcp_v4_send_ack(sk, skb, seq,
tcp_rsk(req)->rcv_nxt,
req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
@@ -1097,6 +1137,8 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
ip_hdr(skb)->tos,
READ_ONCE(tcp_rsk(req)->txhash));
+ if (tcp_key_is_ao(&key))
+ kfree(key.traffic_key);
}

/*
@@ -1635,6 +1677,10 @@ const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
.req_md5_lookup = tcp_v4_md5_lookup,
.calc_md5_hash = tcp_v4_md5_hash_skb,
#endif
+#ifdef CONFIG_TCP_AO
+ .ao_lookup = tcp_v4_ao_lookup_rsk,
+ .ao_calc_key = tcp_v4_ao_calc_key_rsk,
+#endif
#ifdef CONFIG_SYN_COOKIES
.cookie_init_seq = cookie_v4_init_sequence,
#endif
@@ -1736,12 +1782,16 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
/* Copy over the MD5 key from the original socket */
addr = (union tcp_md5_addr *)&newinet->inet_daddr;
key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
- if (key) {
+ if (key && !tcp_rsk_used_ao(req)) {
if (tcp_md5_key_copy(newsk, addr, AF_INET, 32, l3index, key))
goto put_and_exit;
sk_gso_disable(newsk);
}
#endif
+#ifdef CONFIG_TCP_AO
+ if (tcp_ao_copy_all_matching(sk, newsk, req, skb, AF_INET))
+ goto put_and_exit; /* OOM, release back memory */
+#endif

if (__inet_inherit_port(sk, newsk) < 0)
goto put_and_exit;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index c60a84526733..a6ece0edf4d7 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -505,6 +505,9 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
const struct tcp_sock *oldtp;
struct tcp_sock *newtp;
u32 seq;
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_key *ao_key;
+#endif

if (!newsk)
return NULL;
@@ -585,6 +588,13 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
#ifdef CONFIG_TCP_MD5SIG
newtp->md5sig_info = NULL; /*XXX*/
#endif
+#ifdef CONFIG_TCP_AO
+ newtp->ao_info = NULL;
+ ao_key = treq->af_specific->ao_lookup(sk, req,
+ tcp_rsk(req)->ao_keyid, -1);
+ if (ao_key)
+ newtp->tcp_header_len += tcp_ao_len(ao_key);
+ #endif
if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len;
newtp->rx_opt.mss_clamp = req->mss;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index edd3e8665c1b..4984e654be65 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -615,6 +615,7 @@ static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb,
* (but it may well be that other scenarios fail similarly).
*/
static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp,
+ const struct tcp_request_sock *tcprsk,
struct tcp_out_options *opts,
struct tcp_key *key)
{
@@ -629,20 +630,28 @@ static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp,
ptr += 4;
} else if (tcp_key_is_ao(key)) {
#ifdef CONFIG_TCP_AO
- struct tcp_ao_key *rnext_key;
- struct tcp_ao_info *ao_info;
- u8 maclen;
+ u8 maclen = tcp_ao_maclen(key->ao_key);

- ao_info = rcu_dereference_check(tp->ao_info,
+ if (tcprsk) {
+ u8 aolen = maclen + sizeof(struct tcp_ao_hdr);
+
+ *ptr++ = htonl((TCPOPT_AO << 24) | (aolen << 16) |
+ (tcprsk->ao_keyid << 8) |
+ (tcprsk->ao_rcv_next));
+ } else {
+ struct tcp_ao_key *rnext_key;
+ struct tcp_ao_info *ao_info;
+
+ ao_info = rcu_dereference_check(tp->ao_info,
lockdep_sock_is_held(&tp->inet_conn.icsk_inet.sk));
- rnext_key = READ_ONCE(ao_info->rnext_key);
- if (WARN_ON_ONCE(!rnext_key))
- goto out_ao;
- maclen = tcp_ao_maclen(key->ao_key);
- *ptr++ = htonl((TCPOPT_AO << 24) |
- (tcp_ao_len(key->ao_key) << 16) |
- (key->ao_key->sndid << 8) |
- (rnext_key->rcvid));
+ rnext_key = READ_ONCE(ao_info->rnext_key);
+ if (WARN_ON_ONCE(!rnext_key))
+ goto out_ao;
+ *ptr++ = htonl((TCPOPT_AO << 24) |
+ (tcp_ao_len(key->ao_key) << 16) |
+ (key->ao_key->sndid << 8) |
+ (rnext_key->rcvid));
+ }
opts->hash_location = (__u8 *)ptr;
ptr += maclen / sizeof(*ptr);
if (unlikely(maclen % sizeof(*ptr))) {
@@ -1384,7 +1393,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
th->window = htons(min(tp->rcv_wnd, 65535U));
}

- tcp_options_write(th, tp, &opts, &key);
+ tcp_options_write(th, tp, NULL, &opts, &key);

if (tcp_key_is_md5(&key)) {
#ifdef CONFIG_TCP_MD5SIG
@@ -3729,7 +3738,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,

/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
th->window = htons(min(req->rsk_rcv_wnd, 65535U));
- tcp_options_write(th, NULL, &opts, &key);
+ tcp_options_write(th, NULL, NULL, &opts, &key);
th->doff = (tcp_header_size >> 2);
TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS);

diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 5014aa663452..ad7a8caa7b2a 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -214,6 +214,8 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
treq->snt_isn = cookie;
treq->ts_off = 0;
treq->txhash = net_tx_rndhash();
+ tcp_ao_syncookie(sk, skb, treq, AF_INET6);
+
if (IS_ENABLED(CONFIG_SMC))
ireq->smc_ok = 0;

diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c
index d08735b6f3c5..c9a6fa84f6ce 100644
--- a/net/ipv6/tcp_ao.c
+++ b/net/ipv6/tcp_ao.c
@@ -49,6 +49,17 @@ static int tcp_v6_ao_calc_key(struct tcp_ao_key *mkt, u8 *key,
return err;
}

+int tcp_v6_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
+ const struct sk_buff *skb,
+ __be32 sisn, __be32 disn)
+{
+ const struct ipv6hdr *iph = ipv6_hdr(skb);
+ const struct tcphdr *th = tcp_hdr(skb);
+
+ return tcp_v6_ao_calc_key(mkt, key, &iph->saddr, &iph->daddr,
+ th->source, th->dest, sisn, disn);
+}
+
int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk, __be32 sisn,
__be32 disn, bool send)
@@ -63,9 +74,21 @@ int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
htons(sk->sk_num), disn, sisn);
}

-static struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk,
- const struct in6_addr *addr,
- int sndid, int rcvid)
+int tcp_v6_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
+ struct request_sock *req)
+{
+ struct inet_request_sock *ireq = inet_rsk(req);
+
+ return tcp_v6_ao_calc_key(mkt, key,
+ &ireq->ir_v6_loc_addr, &ireq->ir_v6_rmt_addr,
+ htons(ireq->ir_num), ireq->ir_rmt_port,
+ htonl(tcp_rsk(req)->snt_isn),
+ htonl(tcp_rsk(req)->rcv_isn));
+}
+
+struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk,
+ const struct in6_addr *addr,
+ int sndid, int rcvid)
{
return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)addr, AF_INET6,
sndid, rcvid);
@@ -80,6 +103,15 @@ struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid);
}

+struct tcp_ao_key *tcp_v6_ao_lookup_rsk(const struct sock *sk,
+ struct request_sock *req,
+ int sndid, int rcvid)
+{
+ struct in6_addr *addr = &inet_rsk(req)->ir_v6_rmt_addr;
+
+ return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid);
+}
+
int tcp_v6_ao_hash_pseudoheader(struct tcp_sigpool *hp,
const struct in6_addr *daddr,
const struct in6_addr *saddr, int nbytes)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 7a871b774730..7d8dcbfe09ea 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -835,6 +835,10 @@ const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
.req_md5_lookup = tcp_v6_md5_lookup,
.calc_md5_hash = tcp_v6_md5_hash_skb,
#endif
+#ifdef CONFIG_TCP_AO
+ .ao_lookup = tcp_v6_ao_lookup_rsk,
+ .ao_calc_key = tcp_v6_ao_calc_key_rsk,
+#endif
#ifdef CONFIG_SYN_COOKIES
.cookie_init_seq = cookie_v6_init_sequence,
#endif
@@ -1189,16 +1193,54 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
{
struct tcp_key key = {};

+#ifdef CONFIG_TCP_AO
+ if (tcp_rsk_used_ao(req)) {
+ const struct in6_addr *addr = &ipv6_hdr(skb)->saddr;
+ const struct tcp_ao_hdr *aoh;
+ int l3index;
+
+ l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
+ return;
+ if (!aoh)
+ return;
+ key.ao_key = tcp_v6_ao_do_lookup(sk, addr, aoh->rnext_keyid, -1);
+ if (unlikely(!key.ao_key)) {
+ /* Send ACK with any matching MKT for the peer */
+ key.ao_key = tcp_v6_ao_do_lookup(sk, addr, -1, -1);
+ /* Matching key disappeared (user removed the key?)
+ * let the handshake timeout.
+ */
+ if (!key.ao_key) {
+ net_info_ratelimited("TCP-AO key for (%pI6, %d)->(%pI6, %d) suddenly disappeared, won't ACK new connection\n",
+ addr,
+ ntohs(tcp_hdr(skb)->source),
+ &ipv6_hdr(skb)->daddr,
+ ntohs(tcp_hdr(skb)->dest));
+ return;
+ }
+ }
+ key.traffic_key = kmalloc(tcp_ao_digest_size(key.ao_key), GFP_ATOMIC);
+ if (!key.traffic_key)
+ return;
+
+ key.type = TCP_KEY_AO;
+ key.rcv_next = aoh->keyid;
+ tcp_v6_ao_calc_key_rsk(key.ao_key, key.traffic_key, req);
+#else
+ if (0) {
+#endif
#ifdef CONFIG_TCP_MD5SIG
- if (static_branch_unlikely(&tcp_md5_needed.key)) {
+ } else if (static_branch_unlikely(&tcp_md5_needed.key)) {
int l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;

key.md5_key = tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr,
l3index);
if (key.md5_key)
key.type = TCP_KEY_MD5;
- }
#endif
+ }

/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
* sk->sk_state == TCP_SYN_RECV -> for Fast Open.
@@ -1217,6 +1259,8 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
&key, ipv6_get_dsfield(ipv6_hdr(skb)), 0,
READ_ONCE(sk->sk_priority),
READ_ONCE(tcp_rsk(req)->txhash));
+ if (tcp_key_is_ao(&key))
+ kfree(key.traffic_key);
}


@@ -1446,19 +1490,26 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
#ifdef CONFIG_TCP_MD5SIG
l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);

- /* Copy over the MD5 key from the original socket */
- key = tcp_v6_md5_do_lookup(sk, &newsk->sk_v6_daddr, l3index);
- if (key) {
- const union tcp_md5_addr *addr;
+ if (!tcp_rsk_used_ao(req)) {
+ /* Copy over the MD5 key from the original socket */
+ key = tcp_v6_md5_do_lookup(sk, &newsk->sk_v6_daddr, l3index);
+ if (key) {
+ const union tcp_md5_addr *addr;

- addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
- if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) {
- inet_csk_prepare_forced_close(newsk);
- tcp_done(newsk);
- goto out;
+ addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
+ if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) {
+ inet_csk_prepare_forced_close(newsk);
+ tcp_done(newsk);
+ goto out;
+ }
}
}
#endif
+#ifdef CONFIG_TCP_AO
+ /* Copy over tcp_ao_info if any */
+ if (tcp_ao_copy_all_matching(sk, newsk, req, skb, AF_INET6))
+ goto out; /* OOM */
+#endif

if (__inet_inherit_port(sk, newsk) < 0) {
inet_csk_prepare_forced_close(newsk);
--
2.42.0

2023-10-09 23:09:11

by Dmitry Safonov

Subject: [PATCH v14 net-next 01/23] net/tcp: Prepare tcp_md5sig_pool for TCP-AO

TCP-AO, similarly to TCP-MD5, needs to allocate tfms on a slow-path,
which is setsockopt() and use crypto ahash requests on fast paths,
which are RX/TX softirqs. Also, it needs a temporary/scratch buffer
for preparing the hash.

Rework tcp_md5sig_pool in order to support other hashing algorithms
than MD5. It will make it possible to share pre-allocated crypto_ahash
descriptors and scratch area between all TCP hash users.

Internally tcp_sigpool calls crypto_clone_ahash() API over pre-allocated
crypto ahash tfm. Kudos to Herbert, who provided this new crypto API.

I was a little concerned over GFP_ATOMIC allocations of ahash and
crypto_request in RX/TX (see tcp_sigpool_start()), so I benchmarked both
"backends" with different algorithms, using patched version of iperf3[2].
On my laptop with i7-7600U @ 2.80GHz:

clone-tfm per-CPU-requests
TCP-MD5 2.25 Gbits/sec 2.30 Gbits/sec
TCP-AO(hmac(sha1)) 2.53 Gbits/sec 2.54 Gbits/sec
TCP-AO(hmac(sha512)) 1.67 Gbits/sec 1.64 Gbits/sec
TCP-AO(hmac(sha384)) 1.77 Gbits/sec 1.80 Gbits/sec
TCP-AO(hmac(sha224)) 1.29 Gbits/sec 1.30 Gbits/sec
TCP-AO(hmac(sha3-512)) 481 Mbits/sec 480 Mbits/sec
TCP-AO(hmac(md5)) 2.07 Gbits/sec 2.12 Gbits/sec
TCP-AO(hmac(rmd160)) 1.01 Gbits/sec 995 Mbits/sec
TCP-AO(cmac(aes128)) [not supporetd yet] 2.11 Gbits/sec

So, it seems that my concerns don't have strong grounds and per-CPU
crypto_request allocation can be dropped/removed from tcp_sigpool once
ciphers get crypto_clone_ahash() support.

[1]: https://lore.kernel.org/all/[email protected]/T/#u
[2]: https://github.com/0x7f454c46/iperf/tree/tcp-md5-ao
Signed-off-by: Dmitry Safonov <[email protected]>
Reviewed-by: Steen Hegelund <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp.h | 50 ++++--
net/ipv4/Kconfig | 4 +
net/ipv4/Makefile | 1 +
net/ipv4/tcp.c | 145 +++-------------
net/ipv4/tcp_ipv4.c | 97 ++++++-----
net/ipv4/tcp_minisocks.c | 21 ++-
net/ipv4/tcp_sigpool.c | 358 +++++++++++++++++++++++++++++++++++++++
net/ipv6/tcp_ipv6.c | 60 +++----
8 files changed, 525 insertions(+), 211 deletions(-)
create mode 100644 net/ipv4/tcp_sigpool.c

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 9eb0a2855311..db25175c19c7 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1703,12 +1703,39 @@ union tcp_md5sum_block {
#endif
};

-/* - pool: digest algorithm, hash description and scratch buffer */
-struct tcp_md5sig_pool {
- struct ahash_request *md5_req;
- void *scratch;
+/*
+ * struct tcp_sigpool - per-CPU pool of ahash_requests
+ * @scratch: per-CPU temporary area, that can be used between
+ * tcp_sigpool_start() and tcp_sigpool_end() to perform
+ * crypto request
+ * @req: pre-allocated ahash request
+ */
+struct tcp_sigpool {
+ void *scratch;
+ struct ahash_request *req;
};

+int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size);
+void tcp_sigpool_get(unsigned int id);
+void tcp_sigpool_release(unsigned int id);
+int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp,
+ const struct sk_buff *skb,
+ unsigned int header_len);
+
+/**
+ * tcp_sigpool_start - disable bh and start using tcp_sigpool_ahash
+ * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
+ * @c: returned tcp_sigpool for usage (uninitialized on failure)
+ *
+ * Returns 0 on success, error otherwise.
+ */
+int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c);
+/**
+ * tcp_sigpool_end - enable bh and stop using tcp_sigpool
+ * @c: tcp_sigpool context that was returned by tcp_sigpool_start()
+ */
+void tcp_sigpool_end(struct tcp_sigpool *c);
+size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len);
/* - functions */
int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
const struct sock *sk, const struct sk_buff *skb);
@@ -1764,17 +1791,12 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
#define tcp_twsk_md5_key(twsk) NULL
#endif

-bool tcp_alloc_md5sig_pool(void);
+int tcp_md5_alloc_sigpool(void);
+void tcp_md5_release_sigpool(void);
+void tcp_md5_add_sigpool(void);
+extern int tcp_md5_sigpool_id;

-struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
-static inline void tcp_put_md5sig_pool(void)
-{
- local_bh_enable();
-}
-
-int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
- unsigned int header_len);
-int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
+int tcp_md5_hash_key(struct tcp_sigpool *hp,
const struct tcp_md5sig_key *key);

/* From tcp_fastopen.c */
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 2dfb12230f08..89e2ab023272 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -741,10 +741,14 @@ config DEFAULT_TCP_CONG
default "bbr" if DEFAULT_BBR
default "cubic"

+config TCP_SIGPOOL
+ tristate
+
config TCP_MD5SIG
bool "TCP: MD5 Signature Option support (RFC2385)"
select CRYPTO
select CRYPTO_MD5
+ select TCP_SIGPOOL
help
RFC2385 specifies a method of giving MD5 protection to TCP sessions.
Its main (only?) use is to protect BGP sessions between core routers
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index b18ba8ef93ad..cd760793cfcb 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o
obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o
obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o
obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o
+obj-$(CONFIG_TCP_SIGPOOL) += tcp_sigpool.o
obj-$(CONFIG_NET_SOCK_MSG) += tcp_bpf.o
obj-$(CONFIG_BPF_SYSCALL) += udp_bpf.o
obj-$(CONFIG_NETLABEL) += cipso_ipv4.o
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9a8b134d8ada..047e205875be 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4293,141 +4293,52 @@ int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
EXPORT_SYMBOL(tcp_getsockopt);

#ifdef CONFIG_TCP_MD5SIG
-static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
-static DEFINE_MUTEX(tcp_md5sig_mutex);
-static bool tcp_md5sig_pool_populated = false;
+int tcp_md5_sigpool_id = -1;
+EXPORT_SYMBOL_GPL(tcp_md5_sigpool_id);

-static void __tcp_alloc_md5sig_pool(void)
+int tcp_md5_alloc_sigpool(void)
{
- struct crypto_ahash *hash;
- int cpu;
+ size_t scratch_size;
+ int ret;

- hash = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
- if (IS_ERR(hash))
- return;
-
- for_each_possible_cpu(cpu) {
- void *scratch = per_cpu(tcp_md5sig_pool, cpu).scratch;
- struct ahash_request *req;
-
- if (!scratch) {
- scratch = kmalloc_node(sizeof(union tcp_md5sum_block) +
- sizeof(struct tcphdr),
- GFP_KERNEL,
- cpu_to_node(cpu));
- if (!scratch)
- return;
- per_cpu(tcp_md5sig_pool, cpu).scratch = scratch;
- }
- if (per_cpu(tcp_md5sig_pool, cpu).md5_req)
- continue;
-
- req = ahash_request_alloc(hash, GFP_KERNEL);
- if (!req)
- return;
-
- ahash_request_set_callback(req, 0, NULL, NULL);
-
- per_cpu(tcp_md5sig_pool, cpu).md5_req = req;
+ scratch_size = sizeof(union tcp_md5sum_block) + sizeof(struct tcphdr);
+ ret = tcp_sigpool_alloc_ahash("md5", scratch_size);
+ if (ret >= 0) {
+ /* As long as any md5 sigpool was allocated, the return
+ * id would stay the same. Re-write the id only for the case
+ * when previously all MD5 keys were deleted and this call
+ * allocates the first MD5 key, which may return a different
+ * sigpool id than was used previously.
+ */
+ WRITE_ONCE(tcp_md5_sigpool_id, ret); /* Avoids the compiler potentially being smart here */
+ return 0;
}
- /* before setting tcp_md5sig_pool_populated, we must commit all writes
- * to memory. See smp_rmb() in tcp_get_md5sig_pool()
- */
- smp_wmb();
- /* Paired with READ_ONCE() from tcp_alloc_md5sig_pool()
- * and tcp_get_md5sig_pool().
- */
- WRITE_ONCE(tcp_md5sig_pool_populated, true);
+ return ret;
}

-bool tcp_alloc_md5sig_pool(void)
+void tcp_md5_release_sigpool(void)
{
- /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
- if (unlikely(!READ_ONCE(tcp_md5sig_pool_populated))) {
- mutex_lock(&tcp_md5sig_mutex);
-
- if (!tcp_md5sig_pool_populated)
- __tcp_alloc_md5sig_pool();
-
- mutex_unlock(&tcp_md5sig_mutex);
- }
- /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
- return READ_ONCE(tcp_md5sig_pool_populated);
+ tcp_sigpool_release(READ_ONCE(tcp_md5_sigpool_id));
}
-EXPORT_SYMBOL(tcp_alloc_md5sig_pool);

-
-/**
- * tcp_get_md5sig_pool - get md5sig_pool for this user
- *
- * We use percpu structure, so if we succeed, we exit with preemption
- * and BH disabled, to make sure another thread or softirq handling
- * wont try to get same context.
- */
-struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
+void tcp_md5_add_sigpool(void)
{
- local_bh_disable();
-
- /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
- if (READ_ONCE(tcp_md5sig_pool_populated)) {
- /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
- smp_rmb();
- return this_cpu_ptr(&tcp_md5sig_pool);
- }
- local_bh_enable();
- return NULL;
+ tcp_sigpool_get(READ_ONCE(tcp_md5_sigpool_id));
}
-EXPORT_SYMBOL(tcp_get_md5sig_pool);

-int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
- const struct sk_buff *skb, unsigned int header_len)
-{
- struct scatterlist sg;
- const struct tcphdr *tp = tcp_hdr(skb);
- struct ahash_request *req = hp->md5_req;
- unsigned int i;
- const unsigned int head_data_len = skb_headlen(skb) > header_len ?
- skb_headlen(skb) - header_len : 0;
- const struct skb_shared_info *shi = skb_shinfo(skb);
- struct sk_buff *frag_iter;
-
- sg_init_table(&sg, 1);
-
- sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
- ahash_request_set_crypt(req, &sg, NULL, head_data_len);
- if (crypto_ahash_update(req))
- return 1;
-
- for (i = 0; i < shi->nr_frags; ++i) {
- const skb_frag_t *f = &shi->frags[i];
- unsigned int offset = skb_frag_off(f);
- struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
-
- sg_set_page(&sg, page, skb_frag_size(f),
- offset_in_page(offset));
- ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
- if (crypto_ahash_update(req))
- return 1;
- }
-
- skb_walk_frags(skb, frag_iter)
- if (tcp_md5_hash_skb_data(hp, frag_iter, 0))
- return 1;
-
- return 0;
-}
-EXPORT_SYMBOL(tcp_md5_hash_skb_data);
-
-int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key)
+int tcp_md5_hash_key(struct tcp_sigpool *hp,
+ const struct tcp_md5sig_key *key)
{
u8 keylen = READ_ONCE(key->keylen); /* paired with WRITE_ONCE() in tcp_md5_do_add */
struct scatterlist sg;

sg_init_one(&sg, key->key, keylen);
- ahash_request_set_crypt(hp->md5_req, &sg, NULL, keylen);
+ ahash_request_set_crypt(hp->req, &sg, NULL, keylen);

- /* We use data_race() because tcp_md5_do_add() might change key->key under us */
- return data_race(crypto_ahash_update(hp->md5_req));
+ /* We use data_race() because tcp_md5_do_add() might change
+ * key->key under us
+ */
+ return data_race(crypto_ahash_update(hp->req));
}
EXPORT_SYMBOL(tcp_md5_hash_key);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a441740616d7..8b9d2b2ca89f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1220,10 +1220,6 @@ static int __tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
key = sock_kmalloc(sk, sizeof(*key), gfp | __GFP_ZERO);
if (!key)
return -ENOMEM;
- if (!tcp_alloc_md5sig_pool()) {
- sock_kfree_s(sk, key, sizeof(*key));
- return -ENOMEM;
- }

memcpy(key->key, newkey, newkeylen);
key->keylen = newkeylen;
@@ -1245,15 +1241,21 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
struct tcp_sock *tp = tcp_sk(sk);

if (!rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))) {
- if (tcp_md5sig_info_add(sk, GFP_KERNEL))
+ if (tcp_md5_alloc_sigpool())
return -ENOMEM;

+ if (tcp_md5sig_info_add(sk, GFP_KERNEL)) {
+ tcp_md5_release_sigpool();
+ return -ENOMEM;
+ }
+
if (!static_branch_inc(&tcp_md5_needed.key)) {
struct tcp_md5sig_info *md5sig;

md5sig = rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk));
rcu_assign_pointer(tp->md5sig_info, NULL);
kfree_rcu(md5sig, rcu);
+ tcp_md5_release_sigpool();
return -EUSERS;
}
}
@@ -1270,8 +1272,12 @@ int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
struct tcp_sock *tp = tcp_sk(sk);

if (!rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))) {
- if (tcp_md5sig_info_add(sk, sk_gfp_mask(sk, GFP_ATOMIC)))
+ tcp_md5_add_sigpool();
+
+ if (tcp_md5sig_info_add(sk, sk_gfp_mask(sk, GFP_ATOMIC))) {
+ tcp_md5_release_sigpool();
return -ENOMEM;
+ }

if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key)) {
struct tcp_md5sig_info *md5sig;
@@ -1280,6 +1286,7 @@ int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
net_warn_ratelimited("Too many TCP-MD5 keys in the system\n");
rcu_assign_pointer(tp->md5sig_info, NULL);
kfree_rcu(md5sig, rcu);
+ tcp_md5_release_sigpool();
return -EUSERS;
}
}
@@ -1379,7 +1386,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
cmd.tcpm_key, cmd.tcpm_keylen);
}

-static int tcp_v4_md5_hash_headers(struct tcp_md5sig_pool *hp,
+static int tcp_v4_md5_hash_headers(struct tcp_sigpool *hp,
__be32 daddr, __be32 saddr,
const struct tcphdr *th, int nbytes)
{
@@ -1399,38 +1406,35 @@ static int tcp_v4_md5_hash_headers(struct tcp_md5sig_pool *hp,
_th->check = 0;

sg_init_one(&sg, bp, sizeof(*bp) + sizeof(*th));
- ahash_request_set_crypt(hp->md5_req, &sg, NULL,
+ ahash_request_set_crypt(hp->req, &sg, NULL,
sizeof(*bp) + sizeof(*th));
- return crypto_ahash_update(hp->md5_req);
+ return crypto_ahash_update(hp->req);
}

static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
__be32 daddr, __be32 saddr, const struct tcphdr *th)
{
- struct tcp_md5sig_pool *hp;
- struct ahash_request *req;
+ struct tcp_sigpool hp;

- hp = tcp_get_md5sig_pool();
- if (!hp)
- goto clear_hash_noput;
- req = hp->md5_req;
+ if (tcp_sigpool_start(tcp_md5_sigpool_id, &hp))
+ goto clear_hash_nostart;

- if (crypto_ahash_init(req))
+ if (crypto_ahash_init(hp.req))
goto clear_hash;
- if (tcp_v4_md5_hash_headers(hp, daddr, saddr, th, th->doff << 2))
+ if (tcp_v4_md5_hash_headers(&hp, daddr, saddr, th, th->doff << 2))
goto clear_hash;
- if (tcp_md5_hash_key(hp, key))
+ if (tcp_md5_hash_key(&hp, key))
goto clear_hash;
- ahash_request_set_crypt(req, NULL, md5_hash, 0);
- if (crypto_ahash_final(req))
+ ahash_request_set_crypt(hp.req, NULL, md5_hash, 0);
+ if (crypto_ahash_final(hp.req))
goto clear_hash;

- tcp_put_md5sig_pool();
+ tcp_sigpool_end(&hp);
return 0;

clear_hash:
- tcp_put_md5sig_pool();
-clear_hash_noput:
+ tcp_sigpool_end(&hp);
+clear_hash_nostart:
memset(md5_hash, 0, 16);
return 1;
}
@@ -1439,9 +1443,8 @@ int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
const struct sock *sk,
const struct sk_buff *skb)
{
- struct tcp_md5sig_pool *hp;
- struct ahash_request *req;
const struct tcphdr *th = tcp_hdr(skb);
+ struct tcp_sigpool hp;
__be32 saddr, daddr;

if (sk) { /* valid for establish/request sockets */
@@ -1453,30 +1456,28 @@ int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
daddr = iph->daddr;
}

- hp = tcp_get_md5sig_pool();
- if (!hp)
- goto clear_hash_noput;
- req = hp->md5_req;
+ if (tcp_sigpool_start(tcp_md5_sigpool_id, &hp))
+ goto clear_hash_nostart;

- if (crypto_ahash_init(req))
+ if (crypto_ahash_init(hp.req))
goto clear_hash;

- if (tcp_v4_md5_hash_headers(hp, daddr, saddr, th, skb->len))
+ if (tcp_v4_md5_hash_headers(&hp, daddr, saddr, th, skb->len))
goto clear_hash;
- if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
+ if (tcp_sigpool_hash_skb_data(&hp, skb, th->doff << 2))
goto clear_hash;
- if (tcp_md5_hash_key(hp, key))
+ if (tcp_md5_hash_key(&hp, key))
goto clear_hash;
- ahash_request_set_crypt(req, NULL, md5_hash, 0);
- if (crypto_ahash_final(req))
+ ahash_request_set_crypt(hp.req, NULL, md5_hash, 0);
+ if (crypto_ahash_final(hp.req))
goto clear_hash;

- tcp_put_md5sig_pool();
+ tcp_sigpool_end(&hp);
return 0;

clear_hash:
- tcp_put_md5sig_pool();
-clear_hash_noput:
+ tcp_sigpool_end(&hp);
+clear_hash_nostart:
memset(md5_hash, 0, 16);
return 1;
}
@@ -2294,6 +2295,18 @@ static int tcp_v4_init_sock(struct sock *sk)
return 0;
}

+#ifdef CONFIG_TCP_MD5SIG
+static void tcp_md5sig_info_free_rcu(struct rcu_head *head)
+{
+ struct tcp_md5sig_info *md5sig;
+
+ md5sig = container_of(head, struct tcp_md5sig_info, rcu);
+ kfree(md5sig);
+ static_branch_slow_dec_deferred(&tcp_md5_needed);
+ tcp_md5_release_sigpool();
+}
+#endif
+
void tcp_v4_destroy_sock(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -2318,10 +2331,12 @@ void tcp_v4_destroy_sock(struct sock *sk)
#ifdef CONFIG_TCP_MD5SIG
/* Clean up the MD5 key list, if any */
if (tp->md5sig_info) {
+ struct tcp_md5sig_info *md5sig;
+
+ md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
tcp_clear_md5_list(sk);
- kfree_rcu(rcu_dereference_protected(tp->md5sig_info, 1), rcu);
- tp->md5sig_info = NULL;
- static_branch_slow_dec_deferred(&tcp_md5_needed);
+ call_rcu(&md5sig->rcu, tcp_md5sig_info_free_rcu);
+ rcu_assign_pointer(tp->md5sig_info, NULL);
}
#endif

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 3f87611077ef..37aff812ca18 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -261,10 +261,9 @@ static void tcp_time_wait_init(struct sock *sk, struct tcp_timewait_sock *tcptw)
tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC);
if (!tcptw->tw_md5_key)
return;
- if (!tcp_alloc_md5sig_pool())
- goto out_free;
if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key))
goto out_free;
+ tcp_md5_add_sigpool();
}
return;
out_free:
@@ -348,16 +347,26 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
}
EXPORT_SYMBOL(tcp_time_wait);

+#ifdef CONFIG_TCP_MD5SIG
+static void tcp_md5_twsk_free_rcu(struct rcu_head *head)
+{
+ struct tcp_md5sig_key *key;
+
+ key = container_of(head, struct tcp_md5sig_key, rcu);
+ kfree(key);
+ static_branch_slow_dec_deferred(&tcp_md5_needed);
+ tcp_md5_release_sigpool();
+}
+#endif
+
void tcp_twsk_destructor(struct sock *sk)
{
#ifdef CONFIG_TCP_MD5SIG
if (static_branch_unlikely(&tcp_md5_needed.key)) {
struct tcp_timewait_sock *twsk = tcp_twsk(sk);

- if (twsk->tw_md5_key) {
- kfree_rcu(twsk->tw_md5_key, rcu);
- static_branch_slow_dec_deferred(&tcp_md5_needed);
- }
+ if (twsk->tw_md5_key)
+ call_rcu(&twsk->tw_md5_key->rcu, tcp_md5_twsk_free_rcu);
}
#endif
}
diff --git a/net/ipv4/tcp_sigpool.c b/net/ipv4/tcp_sigpool.c
new file mode 100644
index 000000000000..65a8eaae2fec
--- /dev/null
+++ b/net/ipv4/tcp_sigpool.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <crypto/hash.h>
+#include <linux/cpu.h>
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/workqueue.h>
+#include <net/tcp.h>
+
+static size_t __scratch_size;
+static DEFINE_PER_CPU(void __rcu *, sigpool_scratch);
+
+struct sigpool_entry {
+ struct crypto_ahash *hash;
+ const char *alg;
+ struct kref kref;
+ uint16_t needs_key:1,
+ reserved:15;
+};
+
+#define CPOOL_SIZE (PAGE_SIZE / sizeof(struct sigpool_entry))
+static struct sigpool_entry cpool[CPOOL_SIZE];
+static unsigned int cpool_populated;
+static DEFINE_MUTEX(cpool_mutex);
+
+/* Slow-path */
+struct scratches_to_free {
+ struct rcu_head rcu;
+ unsigned int cnt;
+ void *scratches[];
+};
+
+static void free_old_scratches(struct rcu_head *head)
+{
+ struct scratches_to_free *stf;
+
+ stf = container_of(head, struct scratches_to_free, rcu);
+ while (stf->cnt--)
+ kfree(stf->scratches[stf->cnt]);
+ kfree(stf);
+}
+
+/**
+ * sigpool_reserve_scratch - re-allocates scratch buffer, slow-path
+ * @size: request size for the scratch/temp buffer
+ */
+static int sigpool_reserve_scratch(size_t size)
+{
+ struct scratches_to_free *stf;
+ size_t stf_sz = struct_size(stf, scratches, num_possible_cpus());
+ int cpu, err = 0;
+
+ lockdep_assert_held(&cpool_mutex);
+ if (__scratch_size >= size)
+ return 0;
+
+ stf = kmalloc(stf_sz, GFP_KERNEL);
+ if (!stf)
+ return -ENOMEM;
+ stf->cnt = 0;
+
+ size = max(size, __scratch_size);
+ cpus_read_lock();
+ for_each_possible_cpu(cpu) {
+ void *scratch, *old_scratch;
+
+ scratch = kmalloc_node(size, GFP_KERNEL, cpu_to_node(cpu));
+ if (!scratch) {
+ err = -ENOMEM;
+ break;
+ }
+
+ old_scratch = rcu_replace_pointer(per_cpu(sigpool_scratch, cpu),
+ scratch, lockdep_is_held(&cpool_mutex));
+ if (!cpu_online(cpu) || !old_scratch) {
+ kfree(old_scratch);
+ continue;
+ }
+ stf->scratches[stf->cnt++] = old_scratch;
+ }
+ cpus_read_unlock();
+ if (!err)
+ __scratch_size = size;
+
+ call_rcu(&stf->rcu, free_old_scratches);
+ return err;
+}
+
+static void sigpool_scratch_free(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ kfree(rcu_replace_pointer(per_cpu(sigpool_scratch, cpu),
+ NULL, lockdep_is_held(&cpool_mutex)));
+ __scratch_size = 0;
+}
+
+static int __cpool_try_clone(struct crypto_ahash *hash)
+{
+ struct crypto_ahash *tmp;
+
+ tmp = crypto_clone_ahash(hash);
+ if (IS_ERR(tmp))
+ return PTR_ERR(tmp);
+
+ crypto_free_ahash(tmp);
+ return 0;
+}
+
+static int __cpool_alloc_ahash(struct sigpool_entry *e, const char *alg)
+{
+ struct crypto_ahash *cpu0_hash;
+ int ret;
+
+ e->alg = kstrdup(alg, GFP_KERNEL);
+ if (!e->alg)
+ return -ENOMEM;
+
+ cpu0_hash = crypto_alloc_ahash(alg, 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(cpu0_hash)) {
+ ret = PTR_ERR(cpu0_hash);
+ goto out_free_alg;
+ }
+
+ e->needs_key = crypto_ahash_get_flags(cpu0_hash) & CRYPTO_TFM_NEED_KEY;
+
+ ret = __cpool_try_clone(cpu0_hash);
+ if (ret)
+ goto out_free_cpu0_hash;
+ e->hash = cpu0_hash;
+ kref_init(&e->kref);
+ return 0;
+
+out_free_cpu0_hash:
+ crypto_free_ahash(cpu0_hash);
+out_free_alg:
+ kfree(e->alg);
+ e->alg = NULL;
+ return ret;
+}
+
+/**
+ * tcp_sigpool_alloc_ahash - allocates pool for ahash requests
+ * @alg: name of async hash algorithm
+ * @scratch_size: reserve a tcp_sigpool::scratch buffer of this size
+ */
+int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size)
+{
+ int i, ret;
+
+ /* slow-path */
+ mutex_lock(&cpool_mutex);
+ ret = sigpool_reserve_scratch(scratch_size);
+ if (ret)
+ goto out;
+ for (i = 0; i < cpool_populated; i++) {
+ if (!cpool[i].alg)
+ continue;
+ if (strcmp(cpool[i].alg, alg))
+ continue;
+
+ if (kref_read(&cpool[i].kref) > 0)
+ kref_get(&cpool[i].kref);
+ else
+ kref_init(&cpool[i].kref);
+ ret = i;
+ goto out;
+ }
+
+ for (i = 0; i < cpool_populated; i++) {
+ if (!cpool[i].alg)
+ break;
+ }
+ if (i >= CPOOL_SIZE) {
+ ret = -ENOSPC;
+ goto out;
+ }
+
+ ret = __cpool_alloc_ahash(&cpool[i], alg);
+ if (!ret) {
+ ret = i;
+ if (i == cpool_populated)
+ cpool_populated++;
+ }
+out:
+ mutex_unlock(&cpool_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tcp_sigpool_alloc_ahash);
+
+static void __cpool_free_entry(struct sigpool_entry *e)
+{
+ crypto_free_ahash(e->hash);
+ kfree(e->alg);
+ memset(e, 0, sizeof(*e));
+}
+
+static void cpool_cleanup_work_cb(struct work_struct *work)
+{
+ bool free_scratch = true;
+ unsigned int i;
+
+ mutex_lock(&cpool_mutex);
+ for (i = 0; i < cpool_populated; i++) {
+ if (kref_read(&cpool[i].kref) > 0) {
+ free_scratch = false;
+ continue;
+ }
+ if (!cpool[i].alg)
+ continue;
+ __cpool_free_entry(&cpool[i]);
+ }
+ if (free_scratch)
+ sigpool_scratch_free();
+ mutex_unlock(&cpool_mutex);
+}
+
+static DECLARE_WORK(cpool_cleanup_work, cpool_cleanup_work_cb);
+static void cpool_schedule_cleanup(struct kref *kref)
+{
+ schedule_work(&cpool_cleanup_work);
+}
+
+/**
+ * tcp_sigpool_release - decreases number of users for a pool. If it was
+ * the last user of the pool, releases any memory that was consumed.
+ * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
+ */
+void tcp_sigpool_release(unsigned int id)
+{
+ if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg))
+ return;
+
+ /* slow-path */
+ kref_put(&cpool[id].kref, cpool_schedule_cleanup);
+}
+EXPORT_SYMBOL_GPL(tcp_sigpool_release);
+
+/**
+ * tcp_sigpool_get - increases number of users (refcounter) for a pool
+ * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
+ */
+void tcp_sigpool_get(unsigned int id)
+{
+ if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg))
+ return;
+ kref_get(&cpool[id].kref);
+}
+EXPORT_SYMBOL_GPL(tcp_sigpool_get);
+
+int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c) __cond_acquires(RCU_BH)
+{
+ struct crypto_ahash *hash;
+
+ rcu_read_lock_bh();
+ if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg)) {
+ rcu_read_unlock_bh();
+ return -EINVAL;
+ }
+
+ hash = crypto_clone_ahash(cpool[id].hash);
+ if (IS_ERR(hash)) {
+ rcu_read_unlock_bh();
+ return PTR_ERR(hash);
+ }
+
+ c->req = ahash_request_alloc(hash, GFP_ATOMIC);
+ if (!c->req) {
+ crypto_free_ahash(hash);
+ rcu_read_unlock_bh();
+ return -ENOMEM;
+ }
+ ahash_request_set_callback(c->req, 0, NULL, NULL);
+
+ /* Pairs with tcp_sigpool_reserve_scratch(), scratch area is
+ * valid (allocated) until tcp_sigpool_end().
+ */
+ c->scratch = rcu_dereference_bh(*this_cpu_ptr(&sigpool_scratch));
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tcp_sigpool_start);
+
+void tcp_sigpool_end(struct tcp_sigpool *c) __releases(RCU_BH)
+{
+ struct crypto_ahash *hash = crypto_ahash_reqtfm(c->req);
+
+ rcu_read_unlock_bh();
+ ahash_request_free(c->req);
+ crypto_free_ahash(hash);
+}
+EXPORT_SYMBOL_GPL(tcp_sigpool_end);
+
+/**
+ * tcp_sigpool_algo - return algorithm of tcp_sigpool
+ * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
+ * @buf: buffer to return name of algorithm
+ * @buf_len: size of @buf
+ */
+size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len)
+{
+ if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg))
+ return -EINVAL;
+
+ return strscpy(buf, cpool[id].alg, buf_len);
+}
+EXPORT_SYMBOL_GPL(tcp_sigpool_algo);
+
+/**
+ * tcp_sigpool_hash_skb_data - hash data in skb with initialized tcp_sigpool
+ * @hp: tcp_sigpool pointer
+ * @skb: buffer to add sign for
+ * @header_len: TCP header length for this segment
+ */
+int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp,
+ const struct sk_buff *skb,
+ unsigned int header_len)
+{
+ const unsigned int head_data_len = skb_headlen(skb) > header_len ?
+ skb_headlen(skb) - header_len : 0;
+ const struct skb_shared_info *shi = skb_shinfo(skb);
+ const struct tcphdr *tp = tcp_hdr(skb);
+ struct ahash_request *req = hp->req;
+ struct sk_buff *frag_iter;
+ struct scatterlist sg;
+ unsigned int i;
+
+ sg_init_table(&sg, 1);
+
+ sg_set_buf(&sg, ((u8 *)tp) + header_len, head_data_len);
+ ahash_request_set_crypt(req, &sg, NULL, head_data_len);
+ if (crypto_ahash_update(req))
+ return 1;
+
+ for (i = 0; i < shi->nr_frags; ++i) {
+ const skb_frag_t *f = &shi->frags[i];
+ unsigned int offset = skb_frag_off(f);
+ struct page *page;
+
+ page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
+ sg_set_page(&sg, page, skb_frag_size(f), offset_in_page(offset));
+ ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
+ if (crypto_ahash_update(req))
+ return 1;
+ }
+
+ skb_walk_frags(skb, frag_iter)
+ if (tcp_sigpool_hash_skb_data(hp, frag_iter, 0))
+ return 1;
+
+ return 0;
+}
+EXPORT_SYMBOL(tcp_sigpool_hash_skb_data);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Per-CPU pool of crypto requests");
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index bfe7d19ff4fd..e1ee6206a49d 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -670,7 +670,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
cmd.tcpm_key, cmd.tcpm_keylen);
}

-static int tcp_v6_md5_hash_headers(struct tcp_md5sig_pool *hp,
+static int tcp_v6_md5_hash_headers(struct tcp_sigpool *hp,
const struct in6_addr *daddr,
const struct in6_addr *saddr,
const struct tcphdr *th, int nbytes)
@@ -691,39 +691,36 @@ static int tcp_v6_md5_hash_headers(struct tcp_md5sig_pool *hp,
_th->check = 0;

sg_init_one(&sg, bp, sizeof(*bp) + sizeof(*th));
- ahash_request_set_crypt(hp->md5_req, &sg, NULL,
+ ahash_request_set_crypt(hp->req, &sg, NULL,
sizeof(*bp) + sizeof(*th));
- return crypto_ahash_update(hp->md5_req);
+ return crypto_ahash_update(hp->req);
}

static int tcp_v6_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
const struct in6_addr *daddr, struct in6_addr *saddr,
const struct tcphdr *th)
{
- struct tcp_md5sig_pool *hp;
- struct ahash_request *req;
+ struct tcp_sigpool hp;

- hp = tcp_get_md5sig_pool();
- if (!hp)
- goto clear_hash_noput;
- req = hp->md5_req;
+ if (tcp_sigpool_start(tcp_md5_sigpool_id, &hp))
+ goto clear_hash_nostart;

- if (crypto_ahash_init(req))
+ if (crypto_ahash_init(hp.req))
goto clear_hash;
- if (tcp_v6_md5_hash_headers(hp, daddr, saddr, th, th->doff << 2))
+ if (tcp_v6_md5_hash_headers(&hp, daddr, saddr, th, th->doff << 2))
goto clear_hash;
- if (tcp_md5_hash_key(hp, key))
+ if (tcp_md5_hash_key(&hp, key))
goto clear_hash;
- ahash_request_set_crypt(req, NULL, md5_hash, 0);
- if (crypto_ahash_final(req))
+ ahash_request_set_crypt(hp.req, NULL, md5_hash, 0);
+ if (crypto_ahash_final(hp.req))
goto clear_hash;

- tcp_put_md5sig_pool();
+ tcp_sigpool_end(&hp);
return 0;

clear_hash:
- tcp_put_md5sig_pool();
-clear_hash_noput:
+ tcp_sigpool_end(&hp);
+clear_hash_nostart:
memset(md5_hash, 0, 16);
return 1;
}
@@ -733,10 +730,9 @@ static int tcp_v6_md5_hash_skb(char *md5_hash,
const struct sock *sk,
const struct sk_buff *skb)
{
- const struct in6_addr *saddr, *daddr;
- struct tcp_md5sig_pool *hp;
- struct ahash_request *req;
const struct tcphdr *th = tcp_hdr(skb);
+ const struct in6_addr *saddr, *daddr;
+ struct tcp_sigpool hp;

if (sk) { /* valid for establish/request sockets */
saddr = &sk->sk_v6_rcv_saddr;
@@ -747,30 +743,28 @@ static int tcp_v6_md5_hash_skb(char *md5_hash,
daddr = &ip6h->daddr;
}

- hp = tcp_get_md5sig_pool();
- if (!hp)
- goto clear_hash_noput;
- req = hp->md5_req;
+ if (tcp_sigpool_start(tcp_md5_sigpool_id, &hp))
+ goto clear_hash_nostart;

- if (crypto_ahash_init(req))
+ if (crypto_ahash_init(hp.req))
goto clear_hash;

- if (tcp_v6_md5_hash_headers(hp, daddr, saddr, th, skb->len))
+ if (tcp_v6_md5_hash_headers(&hp, daddr, saddr, th, skb->len))
goto clear_hash;
- if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
+ if (tcp_sigpool_hash_skb_data(&hp, skb, th->doff << 2))
goto clear_hash;
- if (tcp_md5_hash_key(hp, key))
+ if (tcp_md5_hash_key(&hp, key))
goto clear_hash;
- ahash_request_set_crypt(req, NULL, md5_hash, 0);
- if (crypto_ahash_final(req))
+ ahash_request_set_crypt(hp.req, NULL, md5_hash, 0);
+ if (crypto_ahash_final(hp.req))
goto clear_hash;

- tcp_put_md5sig_pool();
+ tcp_sigpool_end(&hp);
return 0;

clear_hash:
- tcp_put_md5sig_pool();
-clear_hash_noput:
+ tcp_sigpool_end(&hp);
+clear_hash_nostart:
memset(md5_hash, 0, 16);
return 1;
}
--
2.42.0

2023-10-09 23:10:04

by Dmitry Safonov

Subject: [PATCH v14 net-next 16/23] net/tcp: Ignore specific ICMPs for TCP-AO connections

Similarly to IPsec, RFC5925 prescribes:
">> A TCP-AO implementation MUST default to ignore incoming ICMPv4
messages of Type 3 (destination unreachable), Codes 2-4 (protocol
unreachable, port unreachable, and fragmentation needed -- ’hard
errors’), and ICMPv6 Type 1 (destination unreachable), Code 1
(administratively prohibited) and Code 4 (port unreachable) intended
for connections in synchronized states (ESTABLISHED, FIN-WAIT-1, FIN-
WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match MKTs."

A selftest (later in patch series) verifies that this attack is not
possible in this TCP-AO implementation.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp_ao.h | 10 ++++++-
include/uapi/linux/snmp.h | 1 +
include/uapi/linux/tcp.h | 4 ++-
net/ipv4/proc.c | 1 +
net/ipv4/tcp_ao.c | 58 +++++++++++++++++++++++++++++++++++++++
net/ipv4/tcp_ipv4.c | 7 +++++
net/ipv6/tcp_ipv6.c | 7 +++++
7 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 8c315c3f31da..eec38e9e6380 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -24,6 +24,7 @@ struct tcp_ao_counters {
atomic64_t pkt_bad;
atomic64_t key_not_found;
atomic64_t ao_required;
+ atomic64_t dropped_icmp;
};

struct tcp_ao_key {
@@ -92,7 +93,8 @@ struct tcp_ao_info {
struct tcp_ao_key *rnext_key;
struct tcp_ao_counters counters;
u32 ao_required :1,
- __unused :31;
+ accept_icmps :1,
+ __unused :30;
__be32 lisn;
__be32 risn;
/* Sequence Number Extension (SNE) are upper 4 bytes for SEQ,
@@ -191,6 +193,7 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp);
void tcp_ao_destroy_sock(struct sock *sk, bool twsk);
void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
+bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code);
enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req,
@@ -274,6 +277,11 @@ static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
{
}

+static inline bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code)
+{
+ return false;
+}
+
static inline enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req, const struct tcp_ao_hdr *aoh)
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 06ddf4cd295c..47a6b47da66f 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -300,6 +300,7 @@ enum
LINUX_MIB_TCPAOBAD, /* TCPAOBad */
LINUX_MIB_TCPAOKEYNOTFOUND, /* TCPAOKeyNotFound */
LINUX_MIB_TCPAOGOOD, /* TCPAOGood */
+ LINUX_MIB_TCPAODROPPEDICMPS, /* TCPAODroppedIcmps */
__LINUX_MIB_MAX
};

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 62543f7c5523..e4ddca6178ca 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -404,7 +404,8 @@ struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */
set_rnext :1, /* corresponding ::rnext */
ao_required :1, /* don't accept non-AO connects */
set_counters :1, /* set/clear ::pkt_* counters */
- reserved :28; /* must be 0 */
+ accept_icmps :1, /* accept incoming ICMPs */
+ reserved :27; /* must be 0 */
__u16 reserved2; /* padding, must be 0 */
__u8 current_key; /* KeyID to set as Current_key */
__u8 rnext; /* KeyID to set as Rnext_key */
@@ -412,6 +413,7 @@ struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */
__u64 pkt_bad; /* failed verification */
__u64 pkt_key_not_found; /* could not find a key to verify */
__u64 pkt_ao_required; /* segments missing TCP-AO sign */
+ __u64 pkt_dropped_icmp; /* ICMPs that were ignored */
} __attribute__((aligned(8)));

/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 3f643cd29cfe..5d3c9c96773e 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -302,6 +302,7 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPAOBad", LINUX_MIB_TCPAOBAD),
SNMP_MIB_ITEM("TCPAOKeyNotFound", LINUX_MIB_TCPAOKEYNOTFOUND),
SNMP_MIB_ITEM("TCPAOGood", LINUX_MIB_TCPAOGOOD),
+ SNMP_MIB_ITEM("TCPAODroppedIcmps", LINUX_MIB_TCPAODROPPEDICMPS),
SNMP_MIB_SENTINEL
};

diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 801174c17853..168073cd1c89 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -15,6 +15,7 @@

#include <net/tcp.h>
#include <net/ipv6.h>
+#include <net/icmp.h>

int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp)
@@ -44,6 +45,60 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
return 1;
}

+bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code)
+{
+ bool ignore_icmp = false;
+ struct tcp_ao_info *ao;
+
+ /* RFC5925, 7.8:
+ * >> A TCP-AO implementation MUST default to ignore incoming ICMPv4
+ * messages of Type 3 (destination unreachable), Codes 2-4 (protocol
+ * unreachable, port unreachable, and fragmentation needed -- ’hard
+ * errors’), and ICMPv6 Type 1 (destination unreachable), Code 1
+ * (administratively prohibited) and Code 4 (port unreachable) intended
+ * for connections in synchronized states (ESTABLISHED, FIN-WAIT-1, FIN-
+ * WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match MKTs.
+ */
+ if (READ_ONCE(sk->sk_family) == AF_INET) {
+ if (type != ICMP_DEST_UNREACH)
+ return false;
+ if (code < ICMP_PROT_UNREACH || code > ICMP_FRAG_NEEDED)
+ return false;
+ } else {
+ if (type != ICMPV6_DEST_UNREACH)
+ return false;
+ if (code != ICMPV6_ADM_PROHIBITED && code != ICMPV6_PORT_UNREACH)
+ return false;
+ }
+
+ rcu_read_lock();
+ switch (sk->sk_state) {
+ case TCP_TIME_WAIT:
+ ao = rcu_dereference(tcp_twsk(sk)->ao_info);
+ break;
+ case TCP_SYN_SENT:
+ case TCP_SYN_RECV:
+ case TCP_LISTEN:
+ case TCP_NEW_SYN_RECV:
+ /* RFC5925 specifies to ignore ICMPs *only* on connections
+ * in synchronized states.
+ */
+ rcu_read_unlock();
+ return false;
+ default:
+ ao = rcu_dereference(tcp_sk(sk)->ao_info);
+ }
+
+ if (ao && !ao->accept_icmps) {
+ ignore_icmp = true;
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAODROPPEDICMPS);
+ atomic64_inc(&ao->counters.dropped_icmp);
+ }
+ rcu_read_unlock();
+
+ return ignore_icmp;
+}
+
/* Optimized version of tcp_ao_do_lookup(): only for sockets for which
* it's known that the keys in ao_info are matching peer's
* family/address/VRF/etc.
@@ -1083,6 +1138,7 @@ int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk,
new_ao->lisn = htonl(tcp_rsk(req)->snt_isn);
new_ao->risn = htonl(tcp_rsk(req)->rcv_isn);
new_ao->ao_required = ao->ao_required;
+ new_ao->accept_icmps = ao->accept_icmps;

if (family == AF_INET) {
addr = (union tcp_ao_addr *)&newsk->sk_daddr;
@@ -1789,9 +1845,11 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
atomic64_set(&ao_info->counters.pkt_bad, cmd.pkt_bad);
atomic64_set(&ao_info->counters.key_not_found, cmd.pkt_key_not_found);
atomic64_set(&ao_info->counters.ao_required, cmd.pkt_ao_required);
+ atomic64_set(&ao_info->counters.dropped_icmp, cmd.pkt_dropped_icmp);
}

ao_info->ao_required = cmd.ao_required;
+ ao_info->accept_icmps = cmd.accept_icmps;
if (new_current)
WRITE_ONCE(ao_info->current_key, new_current);
if (new_rnext)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 48fb81a8a712..772fc6347302 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -493,6 +493,8 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
return -ENOENT;
}
if (sk->sk_state == TCP_TIME_WAIT) {
+ /* To increase the counter of ignored icmps for TCP-AO */
+ tcp_ao_ignore_icmp(sk, type, code);
inet_twsk_put(inet_twsk(sk));
return 0;
}
@@ -506,6 +508,11 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
return 0;
}

+ if (tcp_ao_ignore_icmp(sk, type, code)) {
+ sock_put(sk);
+ return 0;
+ }
+
bh_lock_sock(sk);
/* If too many ICMPs get dropped on busy
* servers this needs to be solved differently.
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 25911302d5e3..b604c870c493 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -395,6 +395,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
}

if (sk->sk_state == TCP_TIME_WAIT) {
+ /* To increase the counter of ignored icmps for TCP-AO */
+ tcp_ao_ignore_icmp(sk, type, code);
inet_twsk_put(inet_twsk(sk));
return 0;
}
@@ -405,6 +407,11 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
return 0;
}

+ if (tcp_ao_ignore_icmp(sk, type, code)) {
+ sock_put(sk);
+ return 0;
+ }
+
bh_lock_sock(sk);
if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
--
2.42.0

2023-10-09 23:10:09

by Dmitry Safonov

Subject: [PATCH v14 net-next 14/23] net/tcp: Add TCP-AO SNE support

Add Sequence Number Extension (SNE) for TCP-AO.
This is needed to protect long-living TCP-AO connections from replaying
attacks after sequence number roll-over, see RFC5925 (6.2).

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp_ao.h | 22 ++++++++++++++++++-
net/ipv4/tcp_ao.c | 46 ++++++++++++++++++++++++++++++++--------
net/ipv4/tcp_input.c | 28 ++++++++++++++++++++++++
net/ipv4/tcp_ipv4.c | 3 ++-
net/ipv4/tcp_minisocks.c | 15 ++++++++++++-
net/ipv6/tcp_ipv6.c | 3 ++-
6 files changed, 104 insertions(+), 13 deletions(-)

diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index b34b9a37c81b..9e37193fe805 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -95,6 +95,25 @@ struct tcp_ao_info {
__unused :31;
__be32 lisn;
__be32 risn;
+ /* Sequence Number Extension (SNE) are upper 4 bytes for SEQ,
+ * that protect TCP-AO connection from replayed old TCP segments.
+ * See RFC5925 (6.2).
+ * In order to get correct SNE, there's a helper tcp_ao_compute_sne().
+ * It needs SEQ basis to understand whereabouts are lower SEQ numbers.
+ * According to that basis vector, it can provide incremented SNE
+ * when SEQ rolls over or provide decremented SNE when there's
+ * a retransmitted segment from before-rolling over.
+ * - for request sockets such basis is rcv_isn/snt_isn, which seems
+ * good enough as it's unexpected to receive 4 Gbytes on reqsk.
+ * - for full sockets the basis is rcv_nxt/snd_una. snd_una is
+ * taken instead of snd_nxt as currently it's easier to track
+ * in tcp_snd_una_update(), rather than updating SNE in all
+ * WRITE_ONCE(tp->snd_nxt, ...)
+ * - for time-wait sockets the basis is tw_rcv_nxt/tw_snd_nxt.
+ * tw_snd_nxt is not expected to change, while tw_rcv_nxt may.
+ */
+ u32 snd_sne;
+ u32 rcv_sne;
atomic_t refcnt; /* Protects twsk destruction */
struct rcu_head rcu;
};
@@ -147,6 +166,7 @@ enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req,
const struct tcp_ao_hdr *aoh);
+u32 tcp_ao_compute_sne(u32 next_sne, u32 next_seq, u32 seq);
struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr,
int family, int sndid, int rcvid);
@@ -156,7 +176,7 @@ int tcp_ao_hash_hdr(unsigned short family, char *ao_hash,
const union tcp_ao_addr *saddr,
const struct tcphdr *th, u32 sne);
int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
- const struct tcp_ao_hdr *aoh, int l3index,
+ const struct tcp_ao_hdr *aoh, int l3index, u32 seq,
struct tcp_ao_key **key, char **traffic_key,
bool *allocated_traffic_key, u8 *keyid, u32 *sne);

diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index f7ee2aecf8fc..deae7209f8a1 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -401,6 +401,21 @@ static int tcp_ao_hash_pseudoheader(unsigned short int family,
return -EAFNOSUPPORT;
}

+u32 tcp_ao_compute_sne(u32 next_sne, u32 next_seq, u32 seq)
+{
+ u32 sne = next_sne;
+
+ if (before(seq, next_seq)) {
+ if (seq > next_seq)
+ sne--;
+ } else {
+ if (seq < next_seq)
+ sne++;
+ }
+
+ return sne;
+}
+
/* tcp_ao_hash_sne(struct tcp_sigpool *hp)
* @hp - used for hashing
* @sne - sne value
@@ -611,7 +626,7 @@ struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
}

int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
- const struct tcp_ao_hdr *aoh, int l3index,
+ const struct tcp_ao_hdr *aoh, int l3index, u32 seq,
struct tcp_ao_key **key, char **traffic_key,
bool *allocated_traffic_key, u8 *keyid, u32 *sne)
{
@@ -639,7 +654,7 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,

sisn = htonl(tcp_rsk(req)->rcv_isn);
disn = htonl(tcp_rsk(req)->snt_isn);
- *sne = 0;
+ *sne = tcp_ao_compute_sne(0, tcp_rsk(req)->snt_isn, seq);
} else {
sisn = th->seq;
disn = 0;
@@ -670,11 +685,15 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
*keyid = (*key)->rcvid;
} else {
struct tcp_ao_key *rnext_key;
+ u32 snd_basis;

- if (sk->sk_state == TCP_TIME_WAIT)
+ if (sk->sk_state == TCP_TIME_WAIT) {
ao_info = rcu_dereference(tcp_twsk(sk)->ao_info);
- else
+ snd_basis = tcp_twsk(sk)->tw_snd_nxt;
+ } else {
ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
+ snd_basis = tcp_sk(sk)->snd_una;
+ }
if (!ao_info)
return -ENOENT;

@@ -684,7 +703,8 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
*traffic_key = snd_other_key(*key);
rnext_key = READ_ONCE(ao_info->rnext_key);
*keyid = rnext_key->rcvid;
- *sne = 0;
+ *sne = tcp_ao_compute_sne(READ_ONCE(ao_info->snd_sne),
+ snd_basis, seq);
}
return 0;
}
@@ -698,6 +718,7 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
struct tcp_ao_info *ao;
void *tkey_buf = NULL;
u8 *traffic_key;
+ u32 sne;

ao = rcu_dereference_protected(tcp_sk(sk)->ao_info,
lockdep_sock_is_held(sk));
@@ -717,8 +738,10 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
tp->af_specific->ao_calc_key_sk(key, traffic_key,
sk, ao->lisn, disn, true);
}
+ sne = tcp_ao_compute_sne(READ_ONCE(ao->snd_sne), READ_ONCE(tp->snd_una),
+ ntohl(th->seq));
tp->af_specific->calc_ao_hash(hash_location, key, sk, skb, traffic_key,
- hash_location - (u8 *)th, 0);
+ hash_location - (u8 *)th, sne);
kfree(tkey_buf);
return 0;
}
@@ -846,7 +869,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
if (unlikely(th->syn && !th->ack))
goto verify_hash;

- sne = 0;
+ sne = tcp_ao_compute_sne(info->rcv_sne, tcp_sk(sk)->rcv_nxt,
+ ntohl(th->seq));
/* Established socket, traffic key are cached */
traffic_key = rcv_other_key(key);
err = tcp_ao_verify_hash(sk, skb, family, info, aoh, key,
@@ -881,14 +905,16 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
/* Make the initial syn the likely case here */
if (unlikely(req)) {
- sne = 0;
+ sne = tcp_ao_compute_sne(0, tcp_rsk(req)->rcv_isn,
+ ntohl(th->seq));
sisn = htonl(tcp_rsk(req)->rcv_isn);
disn = htonl(tcp_rsk(req)->snt_isn);
} else if (unlikely(th->ack && !th->syn)) {
/* Possible syncookie packet */
sisn = htonl(ntohl(th->seq) - 1);
disn = htonl(ntohl(th->ack_seq) - 1);
- sne = 0;
+ sne = tcp_ao_compute_sne(0, ntohl(sisn),
+ ntohl(th->seq));
} else if (unlikely(!th->syn)) {
/* no way to figure out initial sisn/disn - drop */
return SKB_DROP_REASON_TCP_FLAGS;
@@ -986,6 +1012,7 @@ void tcp_ao_connect_init(struct sock *sk)
tp->tcp_header_len += tcp_ao_len(key);

ao_info->lisn = htonl(tp->write_seq);
+ ao_info->snd_sne = 0;
} else {
/* TODO: probably, it should fail to connect() here */
rcu_assign_pointer(tp->ao_info, NULL);
@@ -1018,6 +1045,7 @@ void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb)
return;

WRITE_ONCE(ao->risn, tcp_hdr(skb)->seq);
+ ao->rcv_sne = 0;

hlist_for_each_entry_rcu(key, &ao->head, node)
tcp_ao_cache_traffic_keys(sk, ao, key);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 520776714591..219c0e2ce803 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3559,9 +3559,18 @@ static inline bool tcp_may_update_window(const struct tcp_sock *tp,
static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
{
u32 delta = ack - tp->snd_una;
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao;
+#endif

sock_owned_by_me((struct sock *)tp);
tp->bytes_acked += delta;
+#ifdef CONFIG_TCP_AO
+ ao = rcu_dereference_protected(tp->ao_info,
+ lockdep_sock_is_held((struct sock *)tp));
+ if (ao && ack < tp->snd_una)
+ ao->snd_sne++;
+#endif
tp->snd_una = ack;
}

@@ -3569,9 +3578,18 @@ static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
{
u32 delta = seq - tp->rcv_nxt;
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao;
+#endif

sock_owned_by_me((struct sock *)tp);
tp->bytes_received += delta;
+#ifdef CONFIG_TCP_AO
+ ao = rcu_dereference_protected(tp->ao_info,
+ lockdep_sock_is_held((struct sock *)tp));
+ if (ao && seq < tp->rcv_nxt)
+ ao->rcv_sne++;
+#endif
WRITE_ONCE(tp->rcv_nxt, seq);
}

@@ -6427,6 +6445,16 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
* simultaneous connect with crossed SYNs.
* Particularly, it can be connect to self.
*/
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao;
+
+ ao = rcu_dereference_protected(tp->ao_info,
+ lockdep_sock_is_held(sk));
+ if (ao) {
+ WRITE_ONCE(ao->risn, th->seq);
+ ao->rcv_sne = 0;
+ }
+#endif
tcp_set_state(sk, TCP_SYN_RECV);

if (tp->rx_opt.saw_tstamp) {
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1e714b26d9ce..48fb81a8a712 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -675,7 +675,7 @@ static bool tcp_v4_ao_sign_reset(const struct sock *sk, struct sk_buff *skb,
u8 keyid;

rcu_read_lock();
- if (tcp_ao_prepare_reset(sk, skb, aoh, l3index,
+ if (tcp_ao_prepare_reset(sk, skb, aoh, l3index, ntohl(reply->seq),
&key, &traffic_key, &allocated_traffic_key,
&keyid, &ao_sne))
goto out;
@@ -1033,6 +1033,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
struct tcp_ao_key *rnext_key;

key.traffic_key = snd_other_key(key.ao_key);
+ key.sne = READ_ONCE(ao_info->snd_sne);
rnext_key = READ_ONCE(ao_info->rnext_key);
key.rcv_next = rnext_key->rcvid;
key.type = TCP_KEY_AO;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index a6ece0edf4d7..96963c15a05e 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -51,6 +51,18 @@ tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw,
return TCP_TW_SUCCESS;
}

+static void twsk_rcv_nxt_update(struct tcp_timewait_sock *tcptw, u32 seq)
+{
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao;
+
+ ao = rcu_dereference(tcptw->ao_info);
+ if (unlikely(ao && seq < tcptw->tw_rcv_nxt))
+ WRITE_ONCE(ao->rcv_sne, ao->rcv_sne + 1);
+#endif
+ tcptw->tw_rcv_nxt = seq;
+}
+
/*
* * Main purpose of TIME-WAIT state is to close connection gracefully,
* when one of ends sits in LAST-ACK or CLOSING retransmitting FIN
@@ -136,7 +148,8 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,

/* FIN arrived, enter true time-wait state. */
tw->tw_substate = TCP_TIME_WAIT;
- tcptw->tw_rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ twsk_rcv_nxt_update(tcptw, TCP_SKB_CB(skb)->end_seq);
+
if (tmp_opt.saw_tstamp) {
tcptw->tw_ts_recent_stamp = ktime_get_seconds();
tcptw->tw_ts_recent = tmp_opt.rcv_tsval;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d022659f40e8..25911302d5e3 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1087,7 +1087,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
int l3index;

l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
- if (tcp_ao_prepare_reset(sk, skb, aoh, l3index,
+ if (tcp_ao_prepare_reset(sk, skb, aoh, l3index, seq,
&key.ao_key, &key.traffic_key,
&allocated_traffic_key,
&key.rcv_next, &key.sne))
@@ -1164,6 +1164,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
/* rcv_next switches to our rcv_next */
rnext_key = READ_ONCE(ao_info->rnext_key);
key.rcv_next = rnext_key->rcvid;
+ key.sne = READ_ONCE(ao_info->snd_sne);
key.type = TCP_KEY_AO;
#else
if (0) {
--
2.42.0

2023-10-09 23:10:13

by Dmitry Safonov

Subject: [PATCH v14 net-next 12/23] net/tcp: Verify inbound TCP-AO signed segments

Now there is a common function to verify signature on TCP segments:
tcp_inbound_hash(). It has checks for all possible cross-interactions
with MD5 signs as well as with unsigned segments.

The rules from RFC5925 are:
(1) Any TCP segment can have at max only one signature.
(2) TCP connections can't switch between using TCP-MD5 and TCP-AO.
(3) TCP-AO connections can't stop using AO, as well as unsigned
connections can't suddenly start using AO.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/dropreason-core.h | 17 ++++
include/net/tcp.h | 53 ++++++++++++-
include/net/tcp_ao.h | 14 ++++
net/ipv4/tcp.c | 39 ++--------
net/ipv4/tcp_ao.c | 142 ++++++++++++++++++++++++++++++++++
net/ipv4/tcp_ipv4.c | 10 +--
net/ipv6/tcp_ao.c | 9 ++-
net/ipv6/tcp_ipv6.c | 11 +--
8 files changed, 248 insertions(+), 47 deletions(-)

diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index 216cde184db1..a01e1860fe25 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -24,6 +24,10 @@
FN(TCP_MD5NOTFOUND) \
FN(TCP_MD5UNEXPECTED) \
FN(TCP_MD5FAILURE) \
+ FN(TCP_AONOTFOUND) \
+ FN(TCP_AOUNEXPECTED) \
+ FN(TCP_AOKEYNOTFOUND) \
+ FN(TCP_AOFAILURE) \
FN(SOCKET_BACKLOG) \
FN(TCP_FLAGS) \
FN(TCP_ZEROWINDOW) \
@@ -162,6 +166,19 @@ enum skb_drop_reason {
* to LINUX_MIB_TCPMD5FAILURE
*/
SKB_DROP_REASON_TCP_MD5FAILURE,
+ /**
+ * @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected
+ */
+ SKB_DROP_REASON_TCP_AONOTFOUND,
+ /**
+ * @SKB_DROP_REASON_TCP_AOUNEXPECTED: TCP-AO hash is present and it
+ * was not expected.
+ */
+ SKB_DROP_REASON_TCP_AOUNEXPECTED,
+ /** @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown */
+ SKB_DROP_REASON_TCP_AOKEYNOTFOUND,
+ /** @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong */
+ SKB_DROP_REASON_TCP_AOFAILURE,
/**
* @SKB_DROP_REASON_SOCKET_BACKLOG: failed to add skb to socket backlog (
* see LINUX_MIB_TCPBACKLOGDROP)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 717887c3d76d..c5c7893c77cc 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1775,7 +1775,7 @@ tcp_md5_do_lookup_any_l3index(const struct sock *sk,
enum skb_drop_reason
tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
const void *saddr, const void *daddr,
- int family, int dif, int sdif);
+ int family, int l3index, const __u8 *hash_location);


#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
@@ -1797,7 +1797,7 @@ tcp_md5_do_lookup_any_l3index(const struct sock *sk,
static inline enum skb_drop_reason
tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
const void *saddr, const void *daddr,
- int family, int dif, int sdif)
+ int family, int l3index, const __u8 *hash_location)
{
return SKB_NOT_DROPPED_YET;
}
@@ -2692,4 +2692,53 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
return false;
}

+/* Called with rcu_read_lock() */
+static inline enum skb_drop_reason
+tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
+ const struct sk_buff *skb,
+ const void *saddr, const void *daddr,
+ int family, int dif, int sdif)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ const struct tcp_ao_hdr *aoh;
+ const __u8 *md5_location;
+ int l3index;
+
+ /* Invalid option or two times meet any of auth options */
+ if (tcp_parse_auth_options(th, &md5_location, &aoh))
+ return SKB_DROP_REASON_TCP_AUTH_HDR;
+
+ if (req) {
+ if (tcp_rsk_used_ao(req) != !!aoh)
+ return SKB_DROP_REASON_TCP_AOFAILURE;
+ }
+
+ /* sdif set, means packet ingressed via a device
+ * in an L3 domain and dif is set to the l3mdev
+ */
+ l3index = sdif ? dif : 0;
+
+ /* Fast path: unsigned segments */
+ if (likely(!md5_location && !aoh)) {
+ /* Drop if there's TCP-MD5 or TCP-AO key with any rcvid/sndid
+ * for the remote peer. On TCP-AO established connection
+ * the last key is impossible to remove, so there's
+ * always at least one current_key.
+ */
+ if (tcp_ao_required(sk, saddr, family))
+ return SKB_DROP_REASON_TCP_AONOTFOUND;
+ if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
+ return SKB_DROP_REASON_TCP_MD5NOTFOUND;
+ }
+ return SKB_NOT_DROPPED_YET;
+ }
+
+ if (aoh)
+ return tcp_inbound_ao_hash(sk, skb, family, req, aoh);
+
+ return tcp_inbound_md5_hash(sk, skb, saddr, daddr, family,
+ l3index, md5_location);
+}
+
#endif /* _TCP_H */
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 56c2e34ad7d2..6e62235c7cae 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -111,6 +111,9 @@ struct tcp6_ao_context {
};

struct tcp_sigpool;
+#define TCP_AO_ESTABLISHED (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | \
+ TCPF_CLOSE | TCPF_CLOSE_WAIT | \
+ TCPF_LAST_ACK | TCPF_CLOSING)

int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
struct tcp_ao_key *key, struct tcphdr *th,
@@ -130,6 +133,10 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp);
void tcp_ao_destroy_sock(struct sock *sk, bool twsk);
void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
+enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
+ const struct sk_buff *skb, unsigned short int family,
+ const struct request_sock *req,
+ const struct tcp_ao_hdr *aoh);
struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr,
int family, int sndid, int rcvid);
@@ -208,6 +215,13 @@ static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
{
}

+static inline enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
+ const struct sk_buff *skb, unsigned short int family,
+ const struct request_sock *req, const struct tcp_ao_hdr *aoh)
+{
+ return SKB_NOT_DROPPED_YET;
+}
+
static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr, int family, int sndid, int rcvid)
{
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f8e6c11e5132..0f801850481f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4363,42 +4363,23 @@ EXPORT_SYMBOL(tcp_md5_hash_key);
enum skb_drop_reason
tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
const void *saddr, const void *daddr,
- int family, int dif, int sdif)
+ int family, int l3index, const __u8 *hash_location)
{
- /*
- * This gets called for each TCP segment that arrives
- * so we want to be efficient.
+ /* This gets called for each TCP segment that has TCP-MD5 option.
* We have 3 drop cases:
* o No MD5 hash and one expected.
* o MD5 hash and we're not expecting one.
* o MD5 hash and its wrong.
*/
- const __u8 *hash_location = NULL;
- struct tcp_md5sig_key *hash_expected;
const struct tcphdr *th = tcp_hdr(skb);
const struct tcp_sock *tp = tcp_sk(sk);
- int genhash, l3index;
+ struct tcp_md5sig_key *key;
u8 newhash[16];
+ int genhash;

- /* sdif set, means packet ingressed via a device
- * in an L3 domain and dif is set to the l3mdev
- */
- l3index = sdif ? dif : 0;
+ key = tcp_md5_do_lookup(sk, l3index, saddr, family);

- hash_expected = tcp_md5_do_lookup(sk, l3index, saddr, family);
- if (tcp_parse_auth_options(th, &hash_location, NULL))
- return SKB_DROP_REASON_TCP_AUTH_HDR;
-
- /* We've parsed the options - do we have a hash? */
- if (!hash_expected && !hash_location)
- return SKB_NOT_DROPPED_YET;
-
- if (hash_expected && !hash_location) {
- NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
- return SKB_DROP_REASON_TCP_MD5NOTFOUND;
- }
-
- if (!hash_expected && hash_location) {
+ if (!key && hash_location) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
return SKB_DROP_REASON_TCP_MD5UNEXPECTED;
}
@@ -4408,14 +4389,10 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
* IPv4-mapped case.
*/
if (family == AF_INET)
- genhash = tcp_v4_md5_hash_skb(newhash,
- hash_expected,
- NULL, skb);
+ genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
else
- genhash = tp->af_specific->calc_md5_hash(newhash,
- hash_expected,
+ genhash = tp->af_specific->calc_md5_hash(newhash, key,
NULL, skb);
-
if (genhash || memcmp(hash_location, newhash, 16) != 0) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
if (family == AF_INET) {
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 0102d0662fca..4813b9283c55 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -761,6 +761,148 @@ void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
treq->maclen = tcp_ao_maclen(key);
}

+static enum skb_drop_reason
+tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
+ unsigned short int family, struct tcp_ao_info *info,
+ const struct tcp_ao_hdr *aoh, struct tcp_ao_key *key,
+ u8 *traffic_key, u8 *phash, u32 sne)
+{
+ u8 maclen = aoh->length - sizeof(struct tcp_ao_hdr);
+ const struct tcphdr *th = tcp_hdr(skb);
+ void *hash_buf = NULL;
+
+ if (maclen != tcp_ao_maclen(key))
+ return SKB_DROP_REASON_TCP_AOFAILURE;
+
+ hash_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
+ if (!hash_buf)
+ return SKB_DROP_REASON_NOT_SPECIFIED;
+
+ /* XXX: make it per-AF callback? */
+ tcp_ao_hash_skb(family, hash_buf, key, sk, skb, traffic_key,
+ (phash - (u8 *)th), sne);
+ if (memcmp(phash, hash_buf, maclen)) {
+ kfree(hash_buf);
+ return SKB_DROP_REASON_TCP_AOFAILURE;
+ }
+ kfree(hash_buf);
+ return SKB_NOT_DROPPED_YET;
+}
+
+enum skb_drop_reason
+tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
+ unsigned short int family, const struct request_sock *req,
+ const struct tcp_ao_hdr *aoh)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ u8 *phash = (u8 *)(aoh + 1); /* hash goes just after the header */
+ struct tcp_ao_info *info;
+ enum skb_drop_reason ret;
+ struct tcp_ao_key *key;
+ __be32 sisn, disn;
+ u8 *traffic_key;
+ u32 sne = 0;
+
+ info = rcu_dereference(tcp_sk(sk)->ao_info);
+ if (!info)
+ return SKB_DROP_REASON_TCP_AOUNEXPECTED;
+
+ if (unlikely(th->syn)) {
+ sisn = th->seq;
+ disn = 0;
+ }
+
+ /* Fast-path */
+ if (likely((1 << sk->sk_state) & TCP_AO_ESTABLISHED)) {
+ enum skb_drop_reason err;
+ struct tcp_ao_key *current_key;
+
+ /* Check if this socket's rnext_key matches the keyid in the
+ * packet. If not we lookup the key based on the keyid
+ * matching the rcvid in the mkt.
+ */
+ key = READ_ONCE(info->rnext_key);
+ if (key->rcvid != aoh->keyid) {
+ key = tcp_ao_established_key(info, -1, aoh->keyid);
+ if (!key)
+ goto key_not_found;
+ }
+
+ /* Delayed retransmitted SYN */
+ if (unlikely(th->syn && !th->ack))
+ goto verify_hash;
+
+ sne = 0;
+ /* Established socket, traffic key are cached */
+ traffic_key = rcv_other_key(key);
+ err = tcp_ao_verify_hash(sk, skb, family, info, aoh, key,
+ traffic_key, phash, sne);
+ if (err)
+ return err;
+ current_key = READ_ONCE(info->current_key);
+ /* Key rotation: the peer asks us to use new key (RNext) */
+ if (unlikely(aoh->rnext_keyid != current_key->sndid)) {
+ /* If the key is not found we do nothing. */
+ key = tcp_ao_established_key(info, aoh->rnext_keyid, -1);
+ if (key)
+ /* pairs with tcp_ao_del_cmd */
+ WRITE_ONCE(info->current_key, key);
+ }
+ return SKB_NOT_DROPPED_YET;
+ }
+
+ /* Lookup key based on peer address and keyid.
+ * current_key and rnext_key must not be used on tcp listen
+ * sockets as otherwise:
+ * - request sockets would race on those key pointers
+ * - tcp_ao_del_cmd() allows async key removal
+ */
+ key = tcp_ao_inbound_lookup(family, sk, skb, -1, aoh->keyid);
+ if (!key)
+ goto key_not_found;
+
+ if (th->syn && !th->ack)
+ goto verify_hash;
+
+ if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
+ /* Make the initial syn the likely case here */
+ if (unlikely(req)) {
+ sne = 0;
+ sisn = htonl(tcp_rsk(req)->rcv_isn);
+ disn = htonl(tcp_rsk(req)->snt_isn);
+ } else if (unlikely(th->ack && !th->syn)) {
+ /* Possible syncookie packet */
+ sisn = htonl(ntohl(th->seq) - 1);
+ disn = htonl(ntohl(th->ack_seq) - 1);
+ sne = 0;
+ } else if (unlikely(!th->syn)) {
+ /* no way to figure out initial sisn/disn - drop */
+ return SKB_DROP_REASON_TCP_FLAGS;
+ }
+ } else if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
+ disn = info->lisn;
+ if (th->syn || th->rst)
+ sisn = th->seq;
+ else
+ sisn = info->risn;
+ } else {
+ WARN_ONCE(1, "TCP-AO: Unexpected sk_state %d", sk->sk_state);
+ return SKB_DROP_REASON_TCP_AOFAILURE;
+ }
+verify_hash:
+ traffic_key = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
+ if (!traffic_key)
+ return SKB_DROP_REASON_NOT_SPECIFIED;
+ tcp_ao_calc_key_skb(key, traffic_key, skb, sisn, disn, family);
+ ret = tcp_ao_verify_hash(sk, skb, family, info, aoh, key,
+ traffic_key, phash, sne);
+ kfree(traffic_key);
+ return ret;
+
+key_not_found:
+ return SKB_DROP_REASON_TCP_AOKEYNOTFOUND;
+}
+
static int tcp_ao_cache_traffic_keys(const struct sock *sk,
struct tcp_ao_info *ao,
struct tcp_ao_key *ao_key)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b4d26d893f9d..1b1ad6da5929 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2202,9 +2202,9 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
drop_reason = SKB_DROP_REASON_XFRM_POLICY;
else
- drop_reason = tcp_inbound_md5_hash(sk, skb,
- &iph->saddr, &iph->daddr,
- AF_INET, dif, sdif);
+ drop_reason = tcp_inbound_hash(sk, req, skb,
+ &iph->saddr, &iph->daddr,
+ AF_INET, dif, sdif);
if (unlikely(drop_reason)) {
sk_drops_add(sk, skb);
reqsk_put(req);
@@ -2281,8 +2281,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
goto discard_and_relse;
}

- drop_reason = tcp_inbound_md5_hash(sk, skb, &iph->saddr,
- &iph->daddr, AF_INET, dif, sdif);
+ drop_reason = tcp_inbound_hash(sk, NULL, skb, &iph->saddr, &iph->daddr,
+ AF_INET, dif, sdif);
if (drop_reason)
goto discard_and_relse;

diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c
index 99753e12c08c..8b04611c9078 100644
--- a/net/ipv6/tcp_ao.c
+++ b/net/ipv6/tcp_ao.c
@@ -53,11 +53,12 @@ int tcp_v6_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
const struct sk_buff *skb,
__be32 sisn, __be32 disn)
{
- const struct ipv6hdr *iph = ipv6_hdr(skb);
- const struct tcphdr *th = tcp_hdr(skb);
+ const struct ipv6hdr *iph = ipv6_hdr(skb);
+ const struct tcphdr *th = tcp_hdr(skb);

- return tcp_v6_ao_calc_key(mkt, key, &iph->saddr, &iph->daddr,
- th->source, th->dest, sisn, disn);
+ return tcp_v6_ao_calc_key(mkt, key, &iph->saddr,
+ &iph->daddr, th->source,
+ th->dest, sisn, disn);
}

int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 05d9ded5a413..aefe0825532e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1782,9 +1782,9 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
drop_reason = SKB_DROP_REASON_XFRM_POLICY;
else
- drop_reason = tcp_inbound_md5_hash(sk, skb,
- &hdr->saddr, &hdr->daddr,
- AF_INET6, dif, sdif);
+ drop_reason = tcp_inbound_hash(sk, req, skb,
+ &hdr->saddr, &hdr->daddr,
+ AF_INET6, dif, sdif);
if (drop_reason) {
sk_drops_add(sk, skb);
reqsk_put(req);
@@ -1858,8 +1858,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
goto discard_and_relse;
}

- drop_reason = tcp_inbound_md5_hash(sk, skb, &hdr->saddr, &hdr->daddr,
- AF_INET6, dif, sdif);
+ drop_reason = tcp_inbound_hash(sk, NULL, skb, &hdr->saddr, &hdr->daddr,
+ AF_INET6, dif, sdif);
if (drop_reason)
goto discard_and_relse;

@@ -2087,6 +2087,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = {
.ao_lookup = tcp_v6_ao_lookup,
.calc_ao_hash = tcp_v4_ao_hash_skb,
.ao_parse = tcp_v6_parse_ao,
+ .ao_calc_key_sk = tcp_v4_ao_calc_key_sk,
#endif
};
#endif
--
2.42.0

2023-10-09 23:10:14

by Dmitry Safonov

Subject: [PATCH v14 net-next 08/23] net/tcp: Add AO sign to RST packets

Wire up sending resets to TCP-AO hashing.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp.h | 7 ++-
include/net/tcp_ao.h | 12 +++++
net/ipv4/tcp_ao.c | 104 ++++++++++++++++++++++++++++++++++++++++++-
net/ipv4/tcp_ipv4.c | 69 ++++++++++++++++++++++------
net/ipv6/tcp_ipv6.c | 96 ++++++++++++++++++++++++++++-----------
5 files changed, 245 insertions(+), 43 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index a619c429a8bd..dc74908ffa5a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2220,7 +2220,12 @@ static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,

struct tcp_key {
union {
- struct tcp_ao_key *ao_key;
+ struct {
+ struct tcp_ao_key *ao_key;
+ u32 sne;
+ char *traffic_key;
+ u8 rcv_next;
+ };
struct tcp_md5sig_key *md5_key;
};
enum {
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index fdd2f5091b98..629ab0365b83 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -120,12 +120,24 @@ int tcp_ao_hash_skb(unsigned short int family,
const u8 *tkey, int hash_offset, u32 sne);
int tcp_parse_ao(struct sock *sk, int cmd, unsigned short int family,
sockptr_t optval, int optlen);
+struct tcp_ao_key *tcp_ao_established_key(struct tcp_ao_info *ao,
+ int sndid, int rcvid);
int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp);
void tcp_ao_destroy_sock(struct sock *sk);
struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
const union tcp_ao_addr *addr,
int family, int sndid, int rcvid);
+int tcp_ao_hash_hdr(unsigned short family, char *ao_hash,
+ struct tcp_ao_key *key, const u8 *tkey,
+ const union tcp_ao_addr *daddr,
+ const union tcp_ao_addr *saddr,
+ const struct tcphdr *th, u32 sne);
+int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
+ const struct tcp_ao_hdr *aoh, int l3index,
+ struct tcp_ao_key **key, char **traffic_key,
+ bool *allocated_traffic_key, u8 *keyid, u32 *sne);
+
/* ipv4 specific functions */
int tcp_v4_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);
struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 6eb9241d14a3..df59924c3828 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -48,8 +48,8 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
* it's known that the keys in ao_info are matching peer's
* family/address/VRF/etc.
*/
-static struct tcp_ao_key *tcp_ao_established_key(struct tcp_ao_info *ao,
- int sndid, int rcvid)
+struct tcp_ao_key *tcp_ao_established_key(struct tcp_ao_info *ao,
+ int sndid, int rcvid)
{
struct tcp_ao_key *key;

@@ -369,6 +369,66 @@ static int tcp_ao_hash_header(struct tcp_sigpool *hp,
return err;
}

+int tcp_ao_hash_hdr(unsigned short int family, char *ao_hash,
+ struct tcp_ao_key *key, const u8 *tkey,
+ const union tcp_ao_addr *daddr,
+ const union tcp_ao_addr *saddr,
+ const struct tcphdr *th, u32 sne)
+{
+ int tkey_len = tcp_ao_digest_size(key);
+ int hash_offset = ao_hash - (char *)th;
+ struct tcp_sigpool hp;
+ void *hash_buf = NULL;
+
+ hash_buf = kmalloc(tkey_len, GFP_ATOMIC);
+ if (!hash_buf)
+ goto clear_hash_noput;
+
+ if (tcp_sigpool_start(key->tcp_sigpool_id, &hp))
+ goto clear_hash_noput;
+
+ if (crypto_ahash_setkey(crypto_ahash_reqtfm(hp.req), tkey, tkey_len))
+ goto clear_hash;
+
+ if (crypto_ahash_init(hp.req))
+ goto clear_hash;
+
+ if (tcp_ao_hash_sne(&hp, sne))
+ goto clear_hash;
+ if (family == AF_INET) {
+ if (tcp_v4_ao_hash_pseudoheader(&hp, daddr->a4.s_addr,
+ saddr->a4.s_addr, th->doff * 4))
+ goto clear_hash;
+#if IS_ENABLED(CONFIG_IPV6)
+ } else if (family == AF_INET6) {
+ if (tcp_v6_ao_hash_pseudoheader(&hp, &daddr->a6,
+ &saddr->a6, th->doff * 4))
+ goto clear_hash;
+#endif
+ } else {
+ WARN_ON_ONCE(1);
+ goto clear_hash;
+ }
+ if (tcp_ao_hash_header(&hp, th, false,
+ ao_hash, hash_offset, tcp_ao_maclen(key)))
+ goto clear_hash;
+ ahash_request_set_crypt(hp.req, NULL, hash_buf, 0);
+ if (crypto_ahash_final(hp.req))
+ goto clear_hash;
+
+ memcpy(ao_hash, hash_buf, tcp_ao_maclen(key));
+ tcp_sigpool_end(&hp);
+ kfree(hash_buf);
+ return 0;
+
+clear_hash:
+ tcp_sigpool_end(&hp);
+clear_hash_noput:
+ memset(ao_hash, 0, tcp_ao_maclen(key));
+ kfree(hash_buf);
+ return 1;
+}
+
int tcp_ao_hash_skb(unsigned short int family,
char *ao_hash, struct tcp_ao_key *key,
const struct sock *sk, const struct sk_buff *skb,
@@ -435,6 +495,46 @@ struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
return tcp_ao_do_lookup(sk, addr, AF_INET, sndid, rcvid);
}

+int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
+ const struct tcp_ao_hdr *aoh, int l3index,
+ struct tcp_ao_key **key, char **traffic_key,
+ bool *allocated_traffic_key, u8 *keyid, u32 *sne)
+{
+ struct tcp_ao_info *ao_info;
+
+ *allocated_traffic_key = false;
+ /* If there's no socket - than initial sisn/disn are unknown.
+ * Drop the segment. RFC5925 (7.7) advises to require graceful
+ * restart [RFC4724]. Alternatively, the RFC5925 advises to
+ * save/restore traffic keys before/after reboot.
+ * Linux TCP-AO support provides TCP_AO_ADD_KEY and TCP_AO_REPAIR
+ * options to restore a socket post-reboot.
+ */
+ if (!sk)
+ return -ENOTCONN;
+
+ if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
+ return -1;
+ } else {
+ struct tcp_ao_key *rnext_key;
+
+ if (sk->sk_state == TCP_TIME_WAIT)
+ return -1;
+ ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
+ if (!ao_info)
+ return -ENOENT;
+
+ *key = tcp_ao_established_key(ao_info, aoh->rnext_keyid, -1);
+ if (!*key)
+ return -ENOENT;
+ *traffic_key = snd_other_key(*key);
+ rnext_key = READ_ONCE(ao_info->rnext_key);
+ *keyid = rnext_key->rcvid;
+ *sne = 0;
+ }
+ return 0;
+}
+
int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
struct tcp_ao_key *key, struct tcphdr *th,
__u8 *hash_location)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index e731f168b1ee..6a7a7736ba6f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -656,6 +656,52 @@ void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
}
EXPORT_SYMBOL(tcp_v4_send_check);

+#define REPLY_OPTIONS_LEN (MAX_TCP_OPTION_SPACE / sizeof(__be32))
+
+static bool tcp_v4_ao_sign_reset(const struct sock *sk, struct sk_buff *skb,
+ const struct tcp_ao_hdr *aoh,
+ struct ip_reply_arg *arg, struct tcphdr *reply,
+ __be32 reply_options[REPLY_OPTIONS_LEN])
+{
+#ifdef CONFIG_TCP_AO
+ int sdif = tcp_v4_sdif(skb);
+ int dif = inet_iif(skb);
+ int l3index = sdif ? dif : 0;
+ bool allocated_traffic_key;
+ struct tcp_ao_key *key;
+ char *traffic_key;
+ bool drop = true;
+ u32 ao_sne = 0;
+ u8 keyid;
+
+ rcu_read_lock();
+ if (tcp_ao_prepare_reset(sk, skb, aoh, l3index,
+ &key, &traffic_key, &allocated_traffic_key,
+ &keyid, &ao_sne))
+ goto out;
+
+ reply_options[0] = htonl((TCPOPT_AO << 24) | (tcp_ao_len(key) << 16) |
+ (aoh->rnext_keyid << 8) | keyid);
+ arg->iov[0].iov_len += round_up(tcp_ao_len(key), 4);
+ reply->doff = arg->iov[0].iov_len / 4;
+
+ if (tcp_ao_hash_hdr(AF_INET, (char *)&reply_options[1],
+ key, traffic_key,
+ (union tcp_ao_addr *)&ip_hdr(skb)->saddr,
+ (union tcp_ao_addr *)&ip_hdr(skb)->daddr,
+ reply, ao_sne))
+ goto out;
+ drop = false;
+out:
+ rcu_read_unlock();
+ if (allocated_traffic_key)
+ kfree(traffic_key);
+ return drop;
+#else
+ return true;
+#endif
+}
+
/*
* This routine will send an RST to the other tcp.
*
@@ -669,28 +715,21 @@ EXPORT_SYMBOL(tcp_v4_send_check);
* Exception: precedence violation. We do not implement it in any case.
*/

-#ifdef CONFIG_TCP_AO
-#define OPTION_BYTES MAX_TCP_OPTION_SPACE
-#elif defined(CONFIG_TCP_MD5SIG)
-#define OPTION_BYTES TCPOLEN_MD5SIG_ALIGNED
-#else
-#define OPTION_BYTES sizeof(__be32)
-#endif
-
static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
{
const struct tcphdr *th = tcp_hdr(skb);
struct {
struct tcphdr th;
- __be32 opt[OPTION_BYTES / sizeof(__be32)];
+ __be32 opt[REPLY_OPTIONS_LEN];
} rep;
+ const __u8 *md5_hash_location = NULL;
+ const struct tcp_ao_hdr *aoh;
struct ip_reply_arg arg;
#ifdef CONFIG_TCP_MD5SIG
- const __u8 *md5_hash_location = NULL;
struct tcp_md5sig_key *key = NULL;
unsigned char newhash[16];
- int genhash;
struct sock *sk1 = NULL;
+ int genhash;
#endif
u64 transmit_time = 0;
struct sock *ctl_sk;
@@ -727,11 +766,15 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
arg.iov[0].iov_len = sizeof(rep.th);

net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
-#ifdef CONFIG_TCP_MD5SIG
+
/* Invalid TCP option size or twice included auth */
- if (tcp_parse_auth_options(tcp_hdr(skb), &md5_hash_location, NULL))
+ if (tcp_parse_auth_options(tcp_hdr(skb), &md5_hash_location, &aoh))
return;

+ if (aoh && tcp_v4_ao_sign_reset(sk, skb, aoh, &arg, &rep.th, rep.opt))
+ return;
+
+#ifdef CONFIG_TCP_MD5SIG
rcu_read_lock();
if (sk && sk_fullsock(sk)) {
const union tcp_md5_addr *addr;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 6ba1fccbfa2e..594eb074e5e5 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -853,8 +853,8 @@ const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {

static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 seq,
u32 ack, u32 win, u32 tsval, u32 tsecr,
- int oif, struct tcp_md5sig_key *key, int rst,
- u8 tclass, __be32 label, u32 priority, u32 txhash)
+ int oif, int rst, u8 tclass, __be32 label,
+ u32 priority, u32 txhash, struct tcp_key *key)
{
const struct tcphdr *th = tcp_hdr(skb);
struct tcphdr *t1;
@@ -869,13 +869,13 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32

if (tsecr)
tot_len += TCPOLEN_TSTAMP_ALIGNED;
-#ifdef CONFIG_TCP_MD5SIG
- if (key)
+ if (tcp_key_is_md5(key))
tot_len += TCPOLEN_MD5SIG_ALIGNED;
-#endif
+ if (tcp_key_is_ao(key))
+ tot_len += tcp_ao_len(key->ao_key);

#ifdef CONFIG_MPTCP
- if (rst && !key) {
+ if (rst && !tcp_key_is_md5(key)) {
mrst = mptcp_reset_option(skb);

if (mrst)
@@ -916,14 +916,28 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
*topt++ = mrst;

#ifdef CONFIG_TCP_MD5SIG
- if (key) {
+ if (tcp_key_is_md5(key)) {
*topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
(TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
- tcp_v6_md5_hash_hdr((__u8 *)topt, key,
+ tcp_v6_md5_hash_hdr((__u8 *)topt, key->md5_key,
&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr, t1);
}
#endif
+#ifdef CONFIG_TCP_AO
+ if (tcp_key_is_ao(key)) {
+ *topt++ = htonl((TCPOPT_AO << 24) |
+ (tcp_ao_len(key->ao_key) << 16) |
+ (key->ao_key->sndid << 8) |
+ (key->rcv_next));
+
+ tcp_ao_hash_hdr(AF_INET6, (char *)topt, key->ao_key,
+ key->traffic_key,
+ (union tcp_ao_addr *)&ipv6_hdr(skb)->saddr,
+ (union tcp_ao_addr *)&ipv6_hdr(skb)->daddr,
+ t1, key->sne);
+ }
+#endif

memset(&fl6, 0, sizeof(fl6));
fl6.daddr = ipv6_hdr(skb)->saddr;
@@ -986,19 +1000,23 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
{
const struct tcphdr *th = tcp_hdr(skb);
struct ipv6hdr *ipv6h = ipv6_hdr(skb);
- u32 seq = 0, ack_seq = 0;
- struct tcp_md5sig_key *key = NULL;
-#ifdef CONFIG_TCP_MD5SIG
const __u8 *md5_hash_location = NULL;
- unsigned char newhash[16];
- int genhash;
- struct sock *sk1 = NULL;
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
+ bool allocated_traffic_key = false;
#endif
+ const struct tcp_ao_hdr *aoh;
+ struct tcp_key key = {};
+ u32 seq = 0, ack_seq = 0;
__be32 label = 0;
u32 priority = 0;
struct net *net;
u32 txhash = 0;
int oif = 0;
+#ifdef CONFIG_TCP_MD5SIG
+ unsigned char newhash[16];
+ int genhash;
+ struct sock *sk1 = NULL;
+#endif

if (th->rst)
return;
@@ -1010,12 +1028,11 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
return;

net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
-#ifdef CONFIG_TCP_MD5SIG
/* Invalid TCP option size or twice included auth */
- if (tcp_parse_auth_options(th, &md5_hash_location, NULL))
+ if (tcp_parse_auth_options(th, &md5_hash_location, &aoh))
return;
-
rcu_read_lock();
+#ifdef CONFIG_TCP_MD5SIG
if (sk && sk_fullsock(sk)) {
int l3index;

@@ -1023,7 +1040,9 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
* in an L3 domain and inet_iif is set to it.
*/
l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
- key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
+ key.md5_key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
+ if (key.md5_key)
+ key.type = TCP_KEY_MD5;
} else if (md5_hash_location) {
int dif = tcp_v6_iif_l3_slave(skb);
int sdif = tcp_v6_sdif(skb);
@@ -1048,11 +1067,12 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
*/
l3index = tcp_v6_sdif(skb) ? dif : 0;

- key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr, l3index);
- if (!key)
+ key.md5_key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr, l3index);
+ if (!key.md5_key)
goto out;
+ key.type = TCP_KEY_MD5;

- genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
+ genhash = tcp_v6_md5_hash_skb(newhash, key.md5_key, NULL, skb);
if (genhash || memcmp(md5_hash_location, newhash, 16) != 0)
goto out;
}
@@ -1064,6 +1084,20 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
(th->doff << 2);

+#ifdef CONFIG_TCP_AO
+ if (aoh) {
+ int l3index;
+
+ l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
+ if (tcp_ao_prepare_reset(sk, skb, aoh, l3index,
+ &key.ao_key, &key.traffic_key,
+ &allocated_traffic_key,
+ &key.rcv_next, &key.sne))
+ goto out;
+ key.type = TCP_KEY_AO;
+ }
+#endif
+
if (sk) {
oif = sk->sk_bound_dev_if;
if (sk_fullsock(sk)) {
@@ -1083,22 +1117,30 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
label = ip6_flowlabel(ipv6h);
}

- tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1,
- ipv6_get_dsfield(ipv6h), label, priority, txhash);
+ tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1,
+ ipv6_get_dsfield(ipv6h), label, priority, txhash,
+ &key);

-#ifdef CONFIG_TCP_MD5SIG
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
out:
+ if (allocated_traffic_key)
+ kfree(key.traffic_key);
rcu_read_unlock();
#endif
}

static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq,
u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,
- struct tcp_md5sig_key *key, u8 tclass,
+ struct tcp_md5sig_key *md5_key, u8 tclass,
__be32 label, u32 priority, u32 txhash)
{
- tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, key, 0,
- tclass, label, priority, txhash);
+ struct tcp_key key = {
+ .md5_key = md5_key,
+ .type = md5_key ? TCP_KEY_MD5 : TCP_KEY_NONE,
+ };
+
+ tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, 0,
+ tclass, label, priority, txhash, &key);
}

static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
--
2.42.0

2023-10-09 23:10:19

by Dmitry Safonov

Subject: [PATCH v14 net-next 18/23] net/tcp: Add TCP-AO getsockopt()s

Introduce getsockopt(TCP_AO_GET_KEYS) that lets a user get TCP-AO keys
and their properties from a socket. The user can provide a filter
to match the specific key to be dumped or ::get_all = 1 may be
used to dump all keys in one syscall.

Add another getsockopt(TCP_AO_INFO) for providing per-socket/per-ao_info
stats: packet counters, Current_key/RNext_key and flags like
::ao_required and ::accept_icmps.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp_ao.h | 12 ++
include/uapi/linux/tcp.h | 63 +++++++--
net/ipv4/tcp.c | 13 ++
net/ipv4/tcp_ao.c | 295 +++++++++++++++++++++++++++++++++++++++
4 files changed, 369 insertions(+), 14 deletions(-)

diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index eec38e9e6380..746bf078e59c 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -194,6 +194,8 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
void tcp_ao_destroy_sock(struct sock *sk, bool twsk);
void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code);
+int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen);
+int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockptr_t optlen);
enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req,
@@ -315,6 +317,16 @@ static inline void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw,
static inline void tcp_ao_connect_init(struct sock *sk)
{
}
+
+static inline int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen)
+{
+ return -ENOPROTOOPT;
+}
+
+static inline int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockptr_t optlen)
+{
+ return -ENOPROTOOPT;
+}
#endif

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 7b9762ab4df8..a411aef00318 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -131,7 +131,8 @@ enum {

#define TCP_AO_ADD_KEY 38 /* Add/Set MKT */
#define TCP_AO_DEL_KEY 39 /* Delete MKT */
-#define TCP_AO_INFO 40 /* Modify TCP-AO per-socket options */
+#define TCP_AO_INFO 40 /* Set/list TCP-AO per-socket options */
+#define TCP_AO_GET_KEYS 41 /* List MKT(s) */

#define TCP_REPAIR_ON 1
#define TCP_REPAIR_OFF 0
@@ -404,21 +405,55 @@ struct tcp_ao_del { /* setsockopt(TCP_AO_DEL_KEY) */
__u8 keyflags; /* see TCP_AO_KEYF_ */
} __attribute__((aligned(8)));

-struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */
- __u32 set_current :1, /* corresponding ::current_key */
- set_rnext :1, /* corresponding ::rnext */
- ao_required :1, /* don't accept non-AO connects */
- set_counters :1, /* set/clear ::pkt_* counters */
- accept_icmps :1, /* accept incoming ICMPs */
+struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO), getsockopt(TCP_AO_INFO) */
+ /* Here 'in' is for setsockopt(), 'out' is for getsockopt() */
+ __u32 set_current :1, /* in/out: corresponding ::current_key */
+ set_rnext :1, /* in/out: corresponding ::rnext */
+ ao_required :1, /* in/out: don't accept non-AO connects */
+ set_counters :1, /* in: set/clear ::pkt_* counters */
+ accept_icmps :1, /* in/out: accept incoming ICMPs */
reserved :27; /* must be 0 */
__u16 reserved2; /* padding, must be 0 */
- __u8 current_key; /* KeyID to set as Current_key */
- __u8 rnext; /* KeyID to set as Rnext_key */
- __u64 pkt_good; /* verified segments */
- __u64 pkt_bad; /* failed verification */
- __u64 pkt_key_not_found; /* could not find a key to verify */
- __u64 pkt_ao_required; /* segments missing TCP-AO sign */
- __u64 pkt_dropped_icmp; /* ICMPs that were ignored */
+ __u8 current_key; /* in/out: KeyID of Current_key */
+ __u8 rnext; /* in/out: keyid of RNext_key */
+ __u64 pkt_good; /* in/out: verified segments */
+ __u64 pkt_bad; /* in/out: failed verification */
+ __u64 pkt_key_not_found; /* in/out: could not find a key to verify */
+ __u64 pkt_ao_required; /* in/out: segments missing TCP-AO sign */
+ __u64 pkt_dropped_icmp; /* in/out: ICMPs that were ignored */
+} __attribute__((aligned(8)));
+
+struct tcp_ao_getsockopt { /* getsockopt(TCP_AO_GET_KEYS) */
+ struct __kernel_sockaddr_storage addr; /* in/out: dump keys for peer
+ * with this address/prefix
+ */
+ char alg_name[64]; /* out: crypto hash algorithm */
+ __u8 key[TCP_AO_MAXKEYLEN];
+ __u32 nkeys; /* in: size of the userspace buffer
+ * @optval, measured in @optlen - the
+ * sizeof(struct tcp_ao_getsockopt)
+ * out: number of keys that matched
+ */
+ __u16 is_current :1, /* in: match and dump Current_key,
+ * out: the dumped key is Current_key
+ */
+
+ is_rnext :1, /* in: match and dump RNext_key,
+ * out: the dumped key is RNext_key
+ */
+ get_all :1, /* in: dump all keys */
+ reserved :13; /* padding, must be 0 */
+ __u8 sndid; /* in/out: dump keys with SendID */
+ __u8 rcvid; /* in/out: dump keys with RecvID */
+ __u8 prefix; /* in/out: dump keys with address/prefix */
+ __u8 maclen; /* out: key's length of authentication
+ * code (hash)
+ */
+ __u8 keyflags; /* in/out: see TCP_AO_KEYF_ */
+ __u8 keylen; /* out: length of ::key */
+ __s32 ifindex; /* in/out: L3 dev index for VRF */
+ __u64 pkt_good; /* out: verified segments */
+ __u64 pkt_bad; /* out: segments that failed verification */
} __attribute__((aligned(8)));

/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index deec1578537a..9248bb6a72ab 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4272,6 +4272,19 @@ int do_tcp_getsockopt(struct sock *sk, int level,
return err;
}
#endif
+ case TCP_AO_GET_KEYS:
+ case TCP_AO_INFO: {
+ int err;
+
+ sockopt_lock_sock(sk);
+ if (optname == TCP_AO_GET_KEYS)
+ err = tcp_ao_get_mkts(sk, optval, optlen);
+ else
+ err = tcp_ao_get_sock_info(sk, optval, optlen);
+ sockopt_release_sock(sk);
+
+ return err;
+ }
default:
return -ENOPROTOOPT;
}
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index ba13e85fcabd..5962df17ecbe 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -1891,3 +1891,298 @@ int tcp_v4_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen)
return tcp_parse_ao(sk, cmd, AF_INET, optval, optlen);
}

+/* tcp_ao_copy_mkts_to_user(ao_info, optval, optlen)
+ *
+ * @ao_info: struct tcp_ao_info on the socket that
+ * socket getsockopt(TCP_AO_GET_KEYS) is executed on
+ * @optval: pointer to array of tcp_ao_getsockopt structures in user space.
+ * Must be != NULL.
+ * @optlen: pointer to size of tcp_ao_getsockopt structure.
+ * Must be != NULL.
+ *
+ * Return value: 0 on success, a negative error number otherwise.
+ *
+ * optval points to an array of tcp_ao_getsockopt structures in user space.
+ * optval[0] is used as both input and output to getsockopt. It determines
+ * which keys are returned by the kernel.
+ * optval[0].nkeys is the size of the array in user space. On return it contains
+ * the number of keys matching the search criteria.
+ * If tcp_ao_getsockopt::get_all is set, then all keys in the socket are
+ * returned, otherwise only keys matching <addr, prefix, sndid, rcvid>
+ * in optval[0] are returned.
+ * optlen is also used as both input and output. The user provides the size
+ * of struct tcp_ao_getsockopt in user space, and the kernel returns the size
+ * of the structure in kernel space.
+ * The size of struct tcp_ao_getsockopt may differ between user and kernel.
+ * There are three cases to consider:
+ * * If usize == ksize, then keys are copied verbatim.
+ * * If usize < ksize, then the userspace has passed an old struct to a
+ * newer kernel. The rest of the trailing bytes in optval[0]
+ * (ksize - usize) are interpreted as 0 by the kernel.
+ * * If usize > ksize, then the userspace has passed a new struct to an
+ * older kernel. The trailing bytes unknown to the kernel (usize - ksize)
+ * are checked to ensure they are zeroed, otherwise -E2BIG is returned.
+ * On return the kernel fills in min(usize, ksize) in each entry of the array.
+ * The layout of the fields in the user and kernel structures is expected to
+ * be the same (including in the 32bit vs 64bit case).
+ */
+static int tcp_ao_copy_mkts_to_user(struct tcp_ao_info *ao_info,
+ sockptr_t optval, sockptr_t optlen)
+{
+ struct tcp_ao_getsockopt opt_in, opt_out;
+ struct tcp_ao_key *key, *current_key;
+ bool do_address_matching = true;
+ union tcp_ao_addr *addr = NULL;
+ unsigned int max_keys; /* maximum number of keys to copy to user */
+ size_t out_offset = 0;
+ size_t bytes_to_write; /* number of bytes to write to user level */
+ int err, user_len;
+ u32 matched_keys; /* keys from ao_info matched so far */
+ int optlen_out;
+ __be16 port = 0;
+
+ if (copy_from_sockptr(&user_len, optlen, sizeof(int)))
+ return -EFAULT;
+
+ if (user_len <= 0)
+ return -EINVAL;
+
+ memset(&opt_in, 0, sizeof(struct tcp_ao_getsockopt));
+ err = copy_struct_from_sockptr(&opt_in, sizeof(opt_in),
+ optval, user_len);
+ if (err < 0)
+ return err;
+
+ if (opt_in.pkt_good || opt_in.pkt_bad)
+ return -EINVAL;
+
+ if (opt_in.reserved != 0)
+ return -EINVAL;
+
+ max_keys = opt_in.nkeys;
+
+ if (opt_in.get_all || opt_in.is_current || opt_in.is_rnext) {
+ if (opt_in.get_all && (opt_in.is_current || opt_in.is_rnext))
+ return -EINVAL;
+ do_address_matching = false;
+ }
+
+ switch (opt_in.addr.ss_family) {
+ case AF_INET: {
+ struct sockaddr_in *sin;
+ __be32 mask;
+
+ sin = (struct sockaddr_in *)&opt_in.addr;
+ port = sin->sin_port;
+ addr = (union tcp_ao_addr *)&sin->sin_addr;
+
+ if (opt_in.prefix > 32)
+ return -EINVAL;
+
+ if (ntohl(sin->sin_addr.s_addr) == INADDR_ANY &&
+ opt_in.prefix != 0)
+ return -EINVAL;
+
+ mask = inet_make_mask(opt_in.prefix);
+ if (sin->sin_addr.s_addr & ~mask)
+ return -EINVAL;
+
+ break;
+ }
+ case AF_INET6: {
+ struct sockaddr_in6 *sin6;
+ struct in6_addr *addr6;
+
+ sin6 = (struct sockaddr_in6 *)&opt_in.addr;
+ addr = (union tcp_ao_addr *)&sin6->sin6_addr;
+ addr6 = &sin6->sin6_addr;
+ port = sin6->sin6_port;
+
+ /* We don't have to change family and @addr here if
+ * ipv6_addr_v4mapped() like in key adding:
+ * tcp_ao_key_cmp() does it. Do the sanity checks though.
+ */
+ if (opt_in.prefix != 0) {
+ if (ipv6_addr_v4mapped(addr6)) {
+ __be32 mask, addr4 = addr6->s6_addr32[3];
+
+ if (opt_in.prefix > 32 ||
+ ntohl(addr4) == INADDR_ANY)
+ return -EINVAL;
+ mask = inet_make_mask(opt_in.prefix);
+ if (addr4 & ~mask)
+ return -EINVAL;
+ } else {
+ struct in6_addr pfx;
+
+ if (ipv6_addr_any(addr6) ||
+ opt_in.prefix > 128)
+ return -EINVAL;
+
+ ipv6_addr_prefix(&pfx, addr6, opt_in.prefix);
+ if (ipv6_addr_cmp(&pfx, addr6))
+ return -EINVAL;
+ }
+ } else if (!ipv6_addr_any(addr6)) {
+ return -EINVAL;
+ }
+ break;
+ }
+ case 0:
+ if (!do_address_matching)
+ break;
+ fallthrough;
+ default:
+ return -EAFNOSUPPORT;
+ }
+
+ if (!do_address_matching) {
+ /* We could just ignore those, but let's do stricter checks */
+ if (addr || port)
+ return -EINVAL;
+ if (opt_in.prefix || opt_in.sndid || opt_in.rcvid)
+ return -EINVAL;
+ }
+
+ bytes_to_write = min_t(int, user_len, sizeof(struct tcp_ao_getsockopt));
+ matched_keys = 0;
+ /* May change in RX, while we're dumping, pre-fetch it */
+ current_key = READ_ONCE(ao_info->current_key);
+
+ hlist_for_each_entry_rcu(key, &ao_info->head, node) {
+ if (opt_in.get_all)
+ goto match;
+
+ if (opt_in.is_current || opt_in.is_rnext) {
+ if (opt_in.is_current && key == current_key)
+ goto match;
+ if (opt_in.is_rnext && key == ao_info->rnext_key)
+ goto match;
+ continue;
+ }
+
+ if (tcp_ao_key_cmp(key, addr, opt_in.prefix,
+ opt_in.addr.ss_family,
+ opt_in.sndid, opt_in.rcvid) != 0)
+ continue;
+match:
+ matched_keys++;
+ if (matched_keys > max_keys)
+ continue;
+
+ memset(&opt_out, 0, sizeof(struct tcp_ao_getsockopt));
+
+ if (key->family == AF_INET) {
+ struct sockaddr_in *sin_out = (struct sockaddr_in *)&opt_out.addr;
+
+ sin_out->sin_family = key->family;
+ sin_out->sin_port = 0;
+ memcpy(&sin_out->sin_addr, &key->addr, sizeof(struct in_addr));
+ } else {
+ struct sockaddr_in6 *sin6_out = (struct sockaddr_in6 *)&opt_out.addr;
+
+ sin6_out->sin6_family = key->family;
+ sin6_out->sin6_port = 0;
+ memcpy(&sin6_out->sin6_addr, &key->addr, sizeof(struct in6_addr));
+ }
+ opt_out.sndid = key->sndid;
+ opt_out.rcvid = key->rcvid;
+ opt_out.prefix = key->prefixlen;
+ opt_out.keyflags = key->keyflags;
+ opt_out.is_current = (key == current_key);
+ opt_out.is_rnext = (key == ao_info->rnext_key);
+ opt_out.nkeys = 0;
+ opt_out.maclen = key->maclen;
+ opt_out.keylen = key->keylen;
+ opt_out.pkt_good = atomic64_read(&key->pkt_good);
+ opt_out.pkt_bad = atomic64_read(&key->pkt_bad);
+ memcpy(&opt_out.key, key->key, key->keylen);
+ tcp_sigpool_algo(key->tcp_sigpool_id, opt_out.alg_name, 64);
+
+ /* Copy key to user */
+ if (copy_to_sockptr_offset(optval, out_offset,
+ &opt_out, bytes_to_write))
+ return -EFAULT;
+ out_offset += user_len;
+ }
+
+ optlen_out = (int)sizeof(struct tcp_ao_getsockopt);
+ if (copy_to_sockptr(optlen, &optlen_out, sizeof(int)))
+ return -EFAULT;
+
+ out_offset = offsetof(struct tcp_ao_getsockopt, nkeys);
+ if (copy_to_sockptr_offset(optval, out_offset,
+ &matched_keys, sizeof(u32)))
+ return -EFAULT;
+
+ return 0;
+}
+
+int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen)
+{
+ struct tcp_ao_info *ao_info;
+
+ ao_info = setsockopt_ao_info(sk);
+ if (IS_ERR(ao_info))
+ return PTR_ERR(ao_info);
+ if (!ao_info)
+ return -ENOENT;
+
+ return tcp_ao_copy_mkts_to_user(ao_info, optval, optlen);
+}
+
+int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockptr_t optlen)
+{
+ struct tcp_ao_info_opt out, in = {};
+ struct tcp_ao_key *current_key;
+ struct tcp_ao_info *ao;
+ int err, len;
+
+ if (copy_from_sockptr(&len, optlen, sizeof(int)))
+ return -EFAULT;
+
+ if (len <= 0)
+ return -EINVAL;
+
+ /* Copying this "in" only to check ::reserved, ::reserved2,
+ * that may be needed to extend (struct tcp_ao_info_opt) and
+ * what getsockopt() provides in future.
+ */
+ err = copy_struct_from_sockptr(&in, sizeof(in), optval, len);
+ if (err)
+ return err;
+
+ if (in.reserved != 0 || in.reserved2 != 0)
+ return -EINVAL;
+
+ ao = setsockopt_ao_info(sk);
+ if (IS_ERR(ao))
+ return PTR_ERR(ao);
+ if (!ao)
+ return -ENOENT;
+
+ memset(&out, 0, sizeof(out));
+ out.ao_required = ao->ao_required;
+ out.accept_icmps = ao->accept_icmps;
+ out.pkt_good = atomic64_read(&ao->counters.pkt_good);
+ out.pkt_bad = atomic64_read(&ao->counters.pkt_bad);
+ out.pkt_key_not_found = atomic64_read(&ao->counters.key_not_found);
+ out.pkt_ao_required = atomic64_read(&ao->counters.ao_required);
+ out.pkt_dropped_icmp = atomic64_read(&ao->counters.dropped_icmp);
+
+ current_key = READ_ONCE(ao->current_key);
+ if (current_key) {
+ out.set_current = 1;
+ out.current_key = current_key->sndid;
+ }
+ if (ao->rnext_key) {
+ out.set_rnext = 1;
+ out.rnext = ao->rnext_key->rcvid;
+ }
+
+ if (copy_to_sockptr(optval, &out, min_t(int, len, sizeof(out))))
+ return -EFAULT;
+
+ return 0;
+}
+
--
2.42.0

2023-10-09 23:10:27

by Dmitry Safonov

Subject: [PATCH v14 net-next 22/23] net/tcp: Add TCP_AO_REPAIR

Add TCP_AO_REPAIR setsockopt(), getsockopt(). They let a user to repair
TCP-AO ISNs/SNEs. Also let the user hack around when (tp->repair) is on
and add ao_info on a socket in any supported state.
As SNEs now can be read/written at any moment, use
WRITE_ONCE()/READ_ONCE() to set/read them.

Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp_ao.h | 14 +++++++
include/uapi/linux/tcp.h | 8 ++++
net/ipv4/tcp.c | 24 +++++++----
net/ipv4/tcp_ao.c | 90 ++++++++++++++++++++++++++++++++++++++--
4 files changed, 125 insertions(+), 11 deletions(-)

diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 4de921989749..5f26b6ce5183 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -199,6 +199,8 @@ void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code);
int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen);
int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockptr_t optlen);
+int tcp_ao_get_repair(struct sock *sk, sockptr_t optval, sockptr_t optlen);
+int tcp_ao_set_repair(struct sock *sk, sockptr_t optval, unsigned int optlen);
enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req, int l3index,
@@ -329,6 +331,18 @@ static inline int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockpt
{
return -ENOPROTOOPT;
}
+
+static inline int tcp_ao_get_repair(struct sock *sk,
+ sockptr_t optval, sockptr_t optlen)
+{
+ return -ENOPROTOOPT;
+}
+
+static inline int tcp_ao_set_repair(struct sock *sk,
+ sockptr_t optval, unsigned int optlen)
+{
+ return -ENOPROTOOPT;
+}
#endif

#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 25d62ecb9532..3440f8bbab46 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -133,6 +133,7 @@ enum {
#define TCP_AO_DEL_KEY 39 /* Delete MKT */
#define TCP_AO_INFO 40 /* Set/list TCP-AO per-socket options */
#define TCP_AO_GET_KEYS 41 /* List MKT(s) */
+#define TCP_AO_REPAIR 42 /* Get/Set SNEs and ISNs */

#define TCP_REPAIR_ON 1
#define TCP_REPAIR_OFF 0
@@ -457,6 +458,13 @@ struct tcp_ao_getsockopt { /* getsockopt(TCP_AO_GET_KEYS) */
__u64 pkt_bad; /* out: segments that failed verification */
} __attribute__((aligned(8)));

+struct tcp_ao_repair { /* {s,g}etsockopt(TCP_AO_REPAIR) */
+ __be32 snt_isn;
+ __be32 rcv_isn;
+ __u32 snd_sne;
+ __u32 rcv_sne;
+} __attribute__((aligned(8)));
+
/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */

#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9248bb6a72ab..a120c8cc9379 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3591,20 +3591,28 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
__tcp_sock_set_quickack(sk, val);
break;

+ case TCP_AO_REPAIR:
+ err = tcp_ao_set_repair(sk, optval, optlen);
+ break;
#ifdef CONFIG_TCP_AO
case TCP_AO_ADD_KEY:
case TCP_AO_DEL_KEY:
case TCP_AO_INFO: {
/* If this is the first TCP-AO setsockopt() on the socket,
- * sk_state has to be LISTEN or CLOSE
+ * sk_state has to be LISTEN or CLOSE. Allow TCP_REPAIR
+ * in any state.
*/
- if (((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) ||
- rcu_dereference_protected(tcp_sk(sk)->ao_info,
+ if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
+ goto ao_parse;
+ if (rcu_dereference_protected(tcp_sk(sk)->ao_info,
lockdep_sock_is_held(sk)))
- err = tp->af_specific->ao_parse(sk, optname, optval,
- optlen);
- else
- err = -EISCONN;
+ goto ao_parse;
+ if (tp->repair)
+ goto ao_parse;
+ err = -EISCONN;
+ break;
+ao_parse:
+ err = tp->af_specific->ao_parse(sk, optname, optval, optlen);
break;
}
#endif
@@ -4272,6 +4280,8 @@ int do_tcp_getsockopt(struct sock *sk, int level,
return err;
}
#endif
+ case TCP_AO_REPAIR:
+ return tcp_ao_get_repair(sk, optval, optlen);
case TCP_AO_GET_KEYS:
case TCP_AO_INFO: {
int err;
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 31ed648559d4..72d043494223 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -1487,6 +1487,16 @@ static struct tcp_ao_info *setsockopt_ao_info(struct sock *sk)
return ERR_PTR(-ESOCKTNOSUPPORT);
}

+static struct tcp_ao_info *getsockopt_ao_info(struct sock *sk)
+{
+ if (sk_fullsock(sk))
+ return rcu_dereference(tcp_sk(sk)->ao_info);
+ else if (sk->sk_state == TCP_TIME_WAIT)
+ return rcu_dereference(tcp_twsk(sk)->ao_info);
+
+ return ERR_PTR(-ESOCKTNOSUPPORT);
+}
+
#define TCP_AO_KEYF_ALL (TCP_AO_KEYF_IFINDEX | TCP_AO_KEYF_EXCLUDE_OPT)
#define TCP_AO_GET_KEYF_VALID (TCP_AO_KEYF_IFINDEX)

@@ -1668,11 +1678,13 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
if (ret < 0)
goto err_free_sock;

- /* Change this condition if we allow adding keys in states
- * like close_wait, syn_sent or fin_wait...
- */
- if (sk->sk_state == TCP_ESTABLISHED)
+ if (!((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))) {
tcp_ao_cache_traffic_keys(sk, ao_info, key);
+ if (first) {
+ ao_info->current_key = key;
+ ao_info->rnext_key = key;
+ }
+ }

tcp_ao_link_mkt(ao_info, key);
if (first) {
@@ -1923,6 +1935,8 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
if (IS_ERR(ao_info))
return PTR_ERR(ao_info);
if (!ao_info) {
+ if (!((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)))
+ return -EINVAL;
ao_info = tcp_ao_alloc_info(GFP_KERNEL);
if (!ao_info)
return -ENOMEM;
@@ -2305,3 +2319,71 @@ int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockptr_t optlen)
return 0;
}

+int tcp_ao_set_repair(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_ao_repair cmd;
+ struct tcp_ao_key *key;
+ struct tcp_ao_info *ao;
+ int err;
+
+ if (optlen < sizeof(cmd))
+ return -EINVAL;
+
+ err = copy_struct_from_sockptr(&cmd, sizeof(cmd), optval, optlen);
+ if (err)
+ return err;
+
+ if (!tp->repair)
+ return -EPERM;
+
+ ao = setsockopt_ao_info(sk);
+ if (IS_ERR(ao))
+ return PTR_ERR(ao);
+ if (!ao)
+ return -ENOENT;
+
+ WRITE_ONCE(ao->lisn, cmd.snt_isn);
+ WRITE_ONCE(ao->risn, cmd.rcv_isn);
+ WRITE_ONCE(ao->snd_sne, cmd.snd_sne);
+ WRITE_ONCE(ao->rcv_sne, cmd.rcv_sne);
+
+ hlist_for_each_entry_rcu(key, &ao->head, node)
+ tcp_ao_cache_traffic_keys(sk, ao, key);
+
+ return 0;
+}
+
+int tcp_ao_get_repair(struct sock *sk, sockptr_t optval, sockptr_t optlen)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_ao_repair opt;
+ struct tcp_ao_info *ao;
+ int len;
+
+ if (copy_from_sockptr(&len, optlen, sizeof(int)))
+ return -EFAULT;
+
+ if (len <= 0)
+ return -EINVAL;
+
+ if (!tp->repair)
+ return -EPERM;
+
+ rcu_read_lock();
+ ao = getsockopt_ao_info(sk);
+ if (IS_ERR_OR_NULL(ao)) {
+ rcu_read_unlock();
+ return ao ? PTR_ERR(ao) : -ENOENT;
+ }
+
+ opt.snt_isn = ao->lisn;
+ opt.rcv_isn = ao->risn;
+ opt.snd_sne = READ_ONCE(ao->snd_sne);
+ opt.rcv_sne = READ_ONCE(ao->rcv_sne);
+ rcu_read_unlock();
+
+ if (copy_to_sockptr(optval, &opt, min_t(int, len, sizeof(opt))))
+ return -EFAULT;
+ return 0;
+}
--
2.42.0

2023-10-09 23:10:30

by Dmitry Safonov

Subject: [PATCH v14 net-next 20/23] net/tcp: Add static_key for TCP-AO

Similarly to TCP-MD5, add a static key to TCP-AO that is patched out
when there are no keys on a machine and dynamically enabled with the
first setsockopt(TCP_AO) adds a key on any socket. The static key is as
well dynamically disabled later when the socket is destructed.

The lifetime of enabled static key here is the same as ao_info: it is
enabled on allocation, passed over from full socket to twsk and
destructed when ao_info is scheduled for destruction.

Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp.h | 24 +++++++++++++++--------
include/net/tcp_ao.h | 2 ++
net/ipv4/tcp_ao.c | 22 +++++++++++++++++++++
net/ipv4/tcp_input.c | 46 +++++++++++++++++++++++++++++---------------
net/ipv4/tcp_ipv4.c | 25 +++++++++++++-----------
net/ipv6/tcp_ipv6.c | 25 +++++++++++++-----------
6 files changed, 98 insertions(+), 46 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index cdc56d0584bb..3c8ee59c0633 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2250,14 +2250,18 @@ static inline void tcp_get_current_key(const struct sock *sk,
#if defined(CONFIG_TCP_AO) || defined(CONFIG_TCP_MD5SIG)
const struct tcp_sock *tp = tcp_sk(sk);
#endif
-#ifdef CONFIG_TCP_AO
- struct tcp_ao_info *ao;

- ao = rcu_dereference_protected(tp->ao_info, lockdep_sock_is_held(sk));
- if (ao) {
- out->ao_key = READ_ONCE(ao->current_key);
- out->type = TCP_KEY_AO;
- return;
+#ifdef CONFIG_TCP_AO
+ if (static_branch_unlikely(&tcp_ao_needed.key)) {
+ struct tcp_ao_info *ao;
+
+ ao = rcu_dereference_protected(tp->ao_info,
+ lockdep_sock_is_held(sk));
+ if (ao) {
+ out->ao_key = READ_ONCE(ao->current_key);
+ out->type = TCP_KEY_AO;
+ return;
+ }
}
#endif
#ifdef CONFIG_TCP_MD5SIG
@@ -2286,7 +2290,8 @@ static inline bool tcp_key_is_md5(const struct tcp_key *key)
static inline bool tcp_key_is_ao(const struct tcp_key *key)
{
#ifdef CONFIG_TCP_AO
- if (key->type == TCP_KEY_AO)
+ if (static_branch_unlikely(&tcp_ao_needed.key) &&
+ key->type == TCP_KEY_AO)
return true;
#endif
return false;
@@ -2680,6 +2685,9 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
struct tcp_ao_info *ao_info;
struct tcp_ao_key *ao_key;

+ if (!static_branch_unlikely(&tcp_ao_needed.key))
+ return false;
+
ao_info = rcu_dereference_check(tcp_sk(sk)->ao_info,
lockdep_sock_is_held(sk));
if (!ao_info)
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 746bf078e59c..ba5b8c409e99 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -151,6 +151,8 @@ do { \

#ifdef CONFIG_TCP_AO
/* TCP-AO structures and functions */
+#include <linux/jump_label.h>
+extern struct static_key_false_deferred tcp_ao_needed;

struct tcp4_ao_context {
__be32 saddr;
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index afd5943a9972..9e8016157a37 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -17,6 +17,8 @@
#include <net/ipv6.h>
#include <net/icmp.h>

+DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_ao_needed, HZ);
+
int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len, struct tcp_sigpool *hp)
{
@@ -50,6 +52,9 @@ bool tcp_ao_ignore_icmp(const struct sock *sk, int type, int code)
bool ignore_icmp = false;
struct tcp_ao_info *ao;

+ if (!static_branch_unlikely(&tcp_ao_needed.key))
+ return false;
+
/* RFC5925, 7.8:
* >> A TCP-AO implementation MUST default to ignore incoming ICMPv4
* messages of Type 3 (destination unreachable), Codes 2-4 (protocol
@@ -185,6 +190,9 @@ static struct tcp_ao_key *__tcp_ao_do_lookup(const struct sock *sk,
struct tcp_ao_key *key;
struct tcp_ao_info *ao;

+ if (!static_branch_unlikely(&tcp_ao_needed.key))
+ return NULL;
+
ao = rcu_dereference_check(tcp_sk(sk)->ao_info,
lockdep_sock_is_held(sk));
if (!ao)
@@ -276,6 +284,7 @@ void tcp_ao_destroy_sock(struct sock *sk, bool twsk)
}

kfree_rcu(ao, rcu);
+ static_branch_slow_dec_deferred(&tcp_ao_needed);
}

void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp)
@@ -1177,6 +1186,11 @@ int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk,
goto free_and_exit;
}

+ if (!static_key_fast_inc_not_disabled(&tcp_ao_needed.key.key)) {
+ ret = -EUSERS;
+ goto free_and_exit;
+ }
+
key_head = rcu_dereference(hlist_first_rcu(&new_ao->head));
first_key = hlist_entry_safe(key_head, struct tcp_ao_key, node);

@@ -1604,6 +1618,10 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,

tcp_ao_link_mkt(ao_info, key);
if (first) {
+ if (!static_branch_inc(&tcp_ao_needed.key)) {
+ ret = -EUSERS;
+ goto err_free_sock;
+ }
sk_gso_disable(sk);
rcu_assign_pointer(tcp_sk(sk)->ao_info, ao_info);
}
@@ -1872,6 +1890,10 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
if (new_rnext)
WRITE_ONCE(ao_info->rnext_key, new_rnext);
if (first) {
+ if (!static_branch_inc(&tcp_ao_needed.key)) {
+ err = -EUSERS;
+ goto out;
+ }
sk_gso_disable(sk);
rcu_assign_pointer(tcp_sk(sk)->ao_info, ao_info);
}
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 219c0e2ce803..a06a9d5d528c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3555,41 +3555,55 @@ static inline bool tcp_may_update_window(const struct tcp_sock *tp,
(ack_seq == tp->snd_wl1 && (nwin > tp->snd_wnd || !nwin));
}

-/* If we update tp->snd_una, also update tp->bytes_acked */
-static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
+static void tcp_snd_sne_update(struct tcp_sock *tp, u32 ack)
{
- u32 delta = ack - tp->snd_una;
#ifdef CONFIG_TCP_AO
struct tcp_ao_info *ao;
-#endif

- sock_owned_by_me((struct sock *)tp);
- tp->bytes_acked += delta;
-#ifdef CONFIG_TCP_AO
+ if (!static_branch_unlikely(&tcp_ao_needed.key))
+ return;
+
ao = rcu_dereference_protected(tp->ao_info,
lockdep_sock_is_held((struct sock *)tp));
if (ao && ack < tp->snd_una)
ao->snd_sne++;
#endif
+}
+
+/* If we update tp->snd_una, also update tp->bytes_acked */
+static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
+{
+ u32 delta = ack - tp->snd_una;
+
+ sock_owned_by_me((struct sock *)tp);
+ tp->bytes_acked += delta;
+ tcp_snd_sne_update(tp, ack);
tp->snd_una = ack;
}

+static void tcp_rcv_sne_update(struct tcp_sock *tp, u32 seq)
+{
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_info *ao;
+
+ if (!static_branch_unlikely(&tcp_ao_needed.key))
+ return;
+
+ ao = rcu_dereference_protected(tp->ao_info,
+ lockdep_sock_is_held((struct sock *)tp));
+ if (ao && seq < tp->rcv_nxt)
+ ao->rcv_sne++;
+#endif
+}
+
/* If we update tp->rcv_nxt, also update tp->bytes_received */
static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
{
u32 delta = seq - tp->rcv_nxt;
-#ifdef CONFIG_TCP_AO
- struct tcp_ao_info *ao;
-#endif

sock_owned_by_me((struct sock *)tp);
tp->bytes_received += delta;
-#ifdef CONFIG_TCP_AO
- ao = rcu_dereference_protected(tp->ao_info,
- lockdep_sock_is_held((struct sock *)tp));
- if (ao && seq < tp->rcv_nxt)
- ao->rcv_sne++;
-#endif
+ tcp_rcv_sne_update(tp, seq);
WRITE_ONCE(tp->rcv_nxt, seq);
}

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 772fc6347302..cb314a28010f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1023,18 +1023,20 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
#ifdef CONFIG_TCP_AO
struct tcp_ao_info *ao_info;

- /* FIXME: the segment to-be-acked is not verified yet */
- ao_info = rcu_dereference(tcptw->ao_info);
- if (ao_info) {
- const struct tcp_ao_hdr *aoh;
+ if (static_branch_unlikely(&tcp_ao_needed.key)) {
+ /* FIXME: the segment to-be-acked is not verified yet */
+ ao_info = rcu_dereference(tcptw->ao_info);
+ if (ao_info) {
+ const struct tcp_ao_hdr *aoh;

- if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh)) {
- inet_twsk_put(tw);
- return;
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh)) {
+ inet_twsk_put(tw);
+ return;
+ }
+
+ if (aoh)
+ key.ao_key = tcp_ao_established_key(ao_info, aoh->rnext_keyid, -1);
}
-
- if (aoh)
- key.ao_key = tcp_ao_established_key(ao_info, aoh->rnext_keyid, -1);
}
if (key.ao_key) {
struct tcp_ao_key *rnext_key;
@@ -1080,7 +1082,8 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
tcp_sk(sk)->snd_nxt;

#ifdef CONFIG_TCP_AO
- if (tcp_rsk_used_ao(req)) {
+ if (static_branch_unlikely(&tcp_ao_needed.key) &&
+ tcp_rsk_used_ao(req)) {
const union tcp_md5_addr *addr;
const struct tcp_ao_hdr *aoh;

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index b604c870c493..602fbf975d14 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1151,17 +1151,19 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
#ifdef CONFIG_TCP_AO
struct tcp_ao_info *ao_info;

- /* FIXME: the segment to-be-acked is not verified yet */
- ao_info = rcu_dereference(tcptw->ao_info);
- if (ao_info) {
- const struct tcp_ao_hdr *aoh;
+ if (static_branch_unlikely(&tcp_ao_needed.key)) {

- /* Invalid TCP option size or twice included auth */
- if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
- goto out;
- if (aoh) {
- key.ao_key = tcp_ao_established_key(ao_info,
- aoh->rnext_keyid, -1);
+ /* FIXME: the segment to-be-acked is not verified yet */
+ ao_info = rcu_dereference(tcptw->ao_info);
+ if (ao_info) {
+ const struct tcp_ao_hdr *aoh;
+
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(tcp_hdr(skb), NULL, &aoh))
+ goto out;
+ if (aoh)
+ key.ao_key = tcp_ao_established_key(ao_info,
+ aoh->rnext_keyid, -1);
}
}
if (key.ao_key) {
@@ -1203,7 +1205,8 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
struct tcp_key key = {};

#ifdef CONFIG_TCP_AO
- if (tcp_rsk_used_ao(req)) {
+ if (static_branch_unlikely(&tcp_ao_needed.key) &&
+ tcp_rsk_used_ao(req)) {
const struct in6_addr *addr = &ipv6_hdr(skb)->saddr;
const struct tcp_ao_hdr *aoh;
int l3index;
--
2.42.0

2023-10-09 23:10:38

by Dmitry Safonov

Subject: [PATCH v14 net-next 17/23] net/tcp: Add option for TCP-AO to (not) hash header

Provide setsockopt() key flag that makes TCP-AO exclude hashing TCP
header for peers that match the key. This is needed for interraction
with middleboxes that may change TCP options, see RFC5925 (9.2).

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/uapi/linux/tcp.h | 5 +++++
net/ipv4/tcp_ao.c | 8 +++++---
2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index e4ddca6178ca..7b9762ab4df8 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -366,6 +366,11 @@ struct tcp_diag_md5sig {
#define TCP_AO_MAXKEYLEN 80

#define TCP_AO_KEYF_IFINDEX (1 << 0) /* L3 ifindex for VRF */
+#define TCP_AO_KEYF_EXCLUDE_OPT (1 << 1) /* "Indicates whether TCP
+ * options other than TCP-AO
+ * are included in the MAC
+ * calculation"
+ */

struct tcp_ao_add { /* setsockopt(TCP_AO_ADD_KEY) */
struct __kernel_sockaddr_storage addr; /* peer's address for the key */
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 168073cd1c89..ba13e85fcabd 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -562,7 +562,8 @@ int tcp_ao_hash_hdr(unsigned short int family, char *ao_hash,
WARN_ON_ONCE(1);
goto clear_hash;
}
- if (tcp_ao_hash_header(&hp, th, false,
+ if (tcp_ao_hash_header(&hp, th,
+ !!(key->keyflags & TCP_AO_KEYF_EXCLUDE_OPT),
ao_hash, hash_offset, tcp_ao_maclen(key)))
goto clear_hash;
ahash_request_set_crypt(hp.req, NULL, hash_buf, 0);
@@ -610,7 +611,8 @@ int tcp_ao_hash_skb(unsigned short int family,
goto clear_hash;
if (tcp_ao_hash_pseudoheader(family, sk, skb, &hp, skb->len))
goto clear_hash;
- if (tcp_ao_hash_header(&hp, th, false,
+ if (tcp_ao_hash_header(&hp, th,
+ !!(key->keyflags & TCP_AO_KEYF_EXCLUDE_OPT),
ao_hash, hash_offset, tcp_ao_maclen(key)))
goto clear_hash;
if (tcp_sigpool_hash_skb_data(&hp, skb, th->doff << 2))
@@ -1451,7 +1453,7 @@ static struct tcp_ao_info *setsockopt_ao_info(struct sock *sk)
return ERR_PTR(-ESOCKTNOSUPPORT);
}

-#define TCP_AO_KEYF_ALL (0)
+#define TCP_AO_KEYF_ALL (TCP_AO_KEYF_EXCLUDE_OPT)

static struct tcp_ao_key *tcp_ao_key_alloc(struct sock *sk,
struct tcp_ao_add *cmd)
--
2.42.0

2023-10-09 23:10:55

by Dmitry Safonov

Subject: [PATCH v14 net-next 07/23] net/tcp: Add tcp_parse_auth_options()

Introduce a helper that:
(1) shares the common code with TCP-MD5 header options parsing
(2) looks for hash signature only once for both TCP-MD5 and TCP-AO
(3) fails with -EEXIST if any TCP sign option is present twice, see
RFC5925 (2.2):
">> A single TCP segment MUST NOT have more than one TCP-AO in its
options sequence. When multiple TCP-AOs appear, TCP MUST discard
the segment."

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/dropreason-core.h | 6 ++++++
include/net/tcp.h | 24 ++++++++++++++++++++-
include/net/tcp_ao.h | 17 ++++++++++++++-
net/ipv4/tcp.c | 3 ++-
net/ipv4/tcp_input.c | 39 ++++++++++++++++++++++++++---------
net/ipv4/tcp_ipv4.c | 15 +++++++++-----
net/ipv6/tcp_ipv6.c | 11 ++++++----
7 files changed, 93 insertions(+), 22 deletions(-)

diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index a587e83fc169..216cde184db1 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -20,6 +20,7 @@
FN(IP_NOPROTO) \
FN(SOCKET_RCVBUFF) \
FN(PROTO_MEM) \
+ FN(TCP_AUTH_HDR) \
FN(TCP_MD5NOTFOUND) \
FN(TCP_MD5UNEXPECTED) \
FN(TCP_MD5FAILURE) \
@@ -141,6 +142,11 @@ enum skb_drop_reason {
* drop out of udp_memory_allocated.
*/
SKB_DROP_REASON_PROTO_MEM,
+ /**
+ * @SKB_DROP_REASON_TCP_AUTH_HDR: TCP-MD5 or TCP-AO hashes are met
+ * twice or set incorrectly.
+ */
+ SKB_DROP_REASON_TCP_AUTH_HDR,
/**
* @SKB_DROP_REASON_TCP_MD5NOTFOUND: no MD5 hash and one expected,
* corresponding to LINUX_MIB_TCPMD5NOTFOUND
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6073726d614b..a619c429a8bd 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -428,7 +428,6 @@ int tcp_mmap(struct file *file, struct socket *sock,
void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
struct tcp_options_received *opt_rx,
int estab, struct tcp_fastopen_cookie *foc);
-const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);

/*
* BPF SKB-less helpers
@@ -2637,6 +2636,29 @@ static inline u64 tcp_transmit_time(const struct sock *sk)
return 0;
}

+static inline int tcp_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const struct tcp_ao_hdr **aoh)
+{
+ const u8 *md5_tmp, *ao_tmp;
+ int ret;
+
+ ret = tcp_do_parse_auth_options(th, &md5_tmp, &ao_tmp);
+ if (ret)
+ return ret;
+
+ if (md5_hash)
+ *md5_hash = md5_tmp;
+
+ if (aoh) {
+ if (!ao_tmp)
+ *aoh = NULL;
+ else
+ *aoh = (struct tcp_ao_hdr *)(ao_tmp - 2);
+ }
+
+ return 0;
+}
+
static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
int family)
{
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 0b86bc05d8cf..fdd2f5091b98 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -152,7 +152,9 @@ int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);
void tcp_ao_established(struct sock *sk);
void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb);
void tcp_ao_connect_init(struct sock *sk);
-
+void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
+ struct tcp_request_sock *treq,
+ unsigned short int family);
#else /* CONFIG_TCP_AO */

static inline int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
@@ -185,4 +187,17 @@ static inline void tcp_ao_connect_init(struct sock *sk)
}
#endif

+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
+int tcp_do_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const u8 **ao_hash);
+#else
+static inline int tcp_do_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const u8 **ao_hash)
+{
+ *md5_hash = NULL;
+ *ao_hash = NULL;
+ return 0;
+}
+#endif
+
#endif /* _TCP_AO_H */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index dfd8fdd0c163..f8e6c11e5132 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4386,7 +4386,8 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
l3index = sdif ? dif : 0;

hash_expected = tcp_md5_do_lookup(sk, l3index, saddr, family);
- hash_location = tcp_parse_md5sig_option(th);
+ if (tcp_parse_auth_options(th, &hash_location, NULL))
+ return SKB_DROP_REASON_TCP_AUTH_HDR;

/* We've parsed the options - do we have a hash? */
if (!hash_expected && !hash_location)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e46cff718d29..5407ef0c1c04 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4238,39 +4238,58 @@ static bool tcp_fast_parse_options(const struct net *net,
return true;
}

-#ifdef CONFIG_TCP_MD5SIG
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
/*
- * Parse MD5 Signature option
+ * Parse Signature options
*/
-const u8 *tcp_parse_md5sig_option(const struct tcphdr *th)
+int tcp_do_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const u8 **ao_hash)
{
int length = (th->doff << 2) - sizeof(*th);
const u8 *ptr = (const u8 *)(th + 1);
+ unsigned int minlen = TCPOLEN_MD5SIG;
+
+ if (IS_ENABLED(CONFIG_TCP_AO))
+ minlen = sizeof(struct tcp_ao_hdr) + 1;
+
+ *md5_hash = NULL;
+ *ao_hash = NULL;

/* If not enough data remaining, we can short cut */
- while (length >= TCPOLEN_MD5SIG) {
+ while (length >= minlen) {
int opcode = *ptr++;
int opsize;

switch (opcode) {
case TCPOPT_EOL:
- return NULL;
+ return 0;
case TCPOPT_NOP:
length--;
continue;
default:
opsize = *ptr++;
if (opsize < 2 || opsize > length)
- return NULL;
- if (opcode == TCPOPT_MD5SIG)
- return opsize == TCPOLEN_MD5SIG ? ptr : NULL;
+ return -EINVAL;
+ if (opcode == TCPOPT_MD5SIG) {
+ if (opsize != TCPOLEN_MD5SIG)
+ return -EINVAL;
+ if (unlikely(*md5_hash || *ao_hash))
+ return -EEXIST;
+ *md5_hash = ptr;
+ } else if (opcode == TCPOPT_AO) {
+ if (opsize <= sizeof(struct tcp_ao_hdr))
+ return -EINVAL;
+ if (unlikely(*md5_hash || *ao_hash))
+ return -EEXIST;
+ *ao_hash = ptr;
+ }
}
ptr += opsize - 2;
length -= opsize;
}
- return NULL;
+ return 0;
}
-EXPORT_SYMBOL(tcp_parse_md5sig_option);
+EXPORT_SYMBOL(tcp_do_parse_auth_options);
#endif

/* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f357538140f6..e731f168b1ee 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -669,7 +669,9 @@ EXPORT_SYMBOL(tcp_v4_send_check);
* Exception: precedence violation. We do not implement it in any case.
*/

-#ifdef CONFIG_TCP_MD5SIG
+#ifdef CONFIG_TCP_AO
+#define OPTION_BYTES MAX_TCP_OPTION_SPACE
+#elif defined(CONFIG_TCP_MD5SIG)
#define OPTION_BYTES TCPOLEN_MD5SIG_ALIGNED
#else
#define OPTION_BYTES sizeof(__be32)
@@ -684,8 +686,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
} rep;
struct ip_reply_arg arg;
#ifdef CONFIG_TCP_MD5SIG
+ const __u8 *md5_hash_location = NULL;
struct tcp_md5sig_key *key = NULL;
- const __u8 *hash_location = NULL;
unsigned char newhash[16];
int genhash;
struct sock *sk1 = NULL;
@@ -726,8 +728,11 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)

net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
#ifdef CONFIG_TCP_MD5SIG
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(tcp_hdr(skb), &md5_hash_location, NULL))
+ return;
+
rcu_read_lock();
- hash_location = tcp_parse_md5sig_option(th);
if (sk && sk_fullsock(sk)) {
const union tcp_md5_addr *addr;
int l3index;
@@ -738,7 +743,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
l3index = tcp_v4_sdif(skb) ? inet_iif(skb) : 0;
addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
- } else if (hash_location) {
+ } else if (md5_hash_location) {
const union tcp_md5_addr *addr;
int sdif = tcp_v4_sdif(skb);
int dif = inet_iif(skb);
@@ -770,7 +775,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)


genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
- if (genhash || memcmp(hash_location, newhash, 16) != 0)
+ if (genhash || memcmp(md5_hash_location, newhash, 16) != 0)
goto out;

}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index c7834d23a8dc..6ba1fccbfa2e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -989,7 +989,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
u32 seq = 0, ack_seq = 0;
struct tcp_md5sig_key *key = NULL;
#ifdef CONFIG_TCP_MD5SIG
- const __u8 *hash_location = NULL;
+ const __u8 *md5_hash_location = NULL;
unsigned char newhash[16];
int genhash;
struct sock *sk1 = NULL;
@@ -1011,8 +1011,11 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)

net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
#ifdef CONFIG_TCP_MD5SIG
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(th, &md5_hash_location, NULL))
+ return;
+
rcu_read_lock();
- hash_location = tcp_parse_md5sig_option(th);
if (sk && sk_fullsock(sk)) {
int l3index;

@@ -1021,7 +1024,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
*/
l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
- } else if (hash_location) {
+ } else if (md5_hash_location) {
int dif = tcp_v6_iif_l3_slave(skb);
int sdif = tcp_v6_sdif(skb);
int l3index;
@@ -1050,7 +1053,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
goto out;

genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
- if (genhash || memcmp(hash_location, newhash, 16) != 0)
+ if (genhash || memcmp(md5_hash_location, newhash, 16) != 0)
goto out;
}
#endif
--
2.42.0

2023-10-09 23:11:45

by Dmitry Safonov

Subject: [PATCH v14 net-next 11/23] net/tcp: Sign SYN-ACK segments with TCP-AO

Similarly to RST segments, wire SYN-ACKs to TCP-AO.
tcp_rsk_used_ao() is handy here to check if the request socket used AO
and needs a signature on the outgoing segments.

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/net/tcp.h | 3 ++
include/net/tcp_ao.h | 6 ++++
net/ipv4/tcp_ao.c | 22 +++++++++++++
net/ipv4/tcp_ipv4.c | 1 +
net/ipv4/tcp_output.c | 72 +++++++++++++++++++++++++++++++++----------
net/ipv6/tcp_ao.c | 22 +++++++++++++
net/ipv6/tcp_ipv6.c | 1 +
7 files changed, 111 insertions(+), 16 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 13657b70d5d7..717887c3d76d 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2183,6 +2183,9 @@ struct tcp_request_sock_ops {
struct request_sock *req,
int sndid, int rcvid);
int (*ao_calc_key)(struct tcp_ao_key *mkt, u8 *key, struct request_sock *sk);
+ int (*ao_synack_hash)(char *ao_hash, struct tcp_ao_key *mkt,
+ struct request_sock *req, const struct sk_buff *skb,
+ int hash_offset, u32 sne);
#endif
#ifdef CONFIG_SYN_COOKIES
__u32 (*cookie_init_seq)(const struct sk_buff *skb,
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index d04b17971c3c..56c2e34ad7d2 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -147,6 +147,9 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
int tcp_v4_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);
struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
int sndid, int rcvid);
+int tcp_v4_ao_synack_hash(char *ao_hash, struct tcp_ao_key *mkt,
+ struct request_sock *req, const struct sk_buff *skb,
+ int hash_offset, u32 sne);
int tcp_v4_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
const struct sock *sk,
__be32 sisn, __be32 disn, bool send);
@@ -181,6 +184,9 @@ int tcp_v6_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
const struct sock *sk, const struct sk_buff *skb,
const u8 *tkey, int hash_offset, u32 sne);
int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);
+int tcp_v6_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key,
+ struct request_sock *req, const struct sk_buff *skb,
+ int hash_offset, u32 sne);
void tcp_ao_established(struct sock *sk);
void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb);
void tcp_ao_connect_init(struct sock *sk);
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index c8006b0cbb8a..0102d0662fca 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -568,6 +568,28 @@ int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
tkey, hash_offset, sne);
}

+int tcp_v4_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key,
+ struct request_sock *req, const struct sk_buff *skb,
+ int hash_offset, u32 sne)
+{
+ void *hash_buf = NULL;
+ int err;
+
+ hash_buf = kmalloc(tcp_ao_digest_size(ao_key), GFP_ATOMIC);
+ if (!hash_buf)
+ return -ENOMEM;
+
+ err = tcp_v4_ao_calc_key_rsk(ao_key, hash_buf, req);
+ if (err)
+ goto out;
+
+ err = tcp_ao_hash_skb(AF_INET, ao_hash, ao_key, req_to_sk(req), skb,
+ hash_buf, hash_offset, sne);
+out:
+ kfree(hash_buf);
+ return err;
+}
+
struct tcp_ao_key *tcp_v4_ao_lookup_rsk(const struct sock *sk,
struct request_sock *req,
int sndid, int rcvid)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index c332a86c22c5..b4d26d893f9d 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1680,6 +1680,7 @@ const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
#ifdef CONFIG_TCP_AO
.ao_lookup = tcp_v4_ao_lookup_rsk,
.ao_calc_key = tcp_v4_ao_calc_key_rsk,
+ .ao_synack_hash = tcp_v4_ao_synack_hash,
#endif
#ifdef CONFIG_SYN_COOKIES
.cookie_init_seq = cookie_v4_init_sequence,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4984e654be65..8d110ee705a4 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -886,7 +886,7 @@ static unsigned int tcp_synack_options(const struct sock *sk,
struct request_sock *req,
unsigned int mss, struct sk_buff *skb,
struct tcp_out_options *opts,
- const struct tcp_md5sig_key *md5,
+ const struct tcp_key *key,
struct tcp_fastopen_cookie *foc,
enum tcp_synack_type synack_type,
struct sk_buff *syn_skb)
@@ -894,8 +894,7 @@ static unsigned int tcp_synack_options(const struct sock *sk,
struct inet_request_sock *ireq = inet_rsk(req);
unsigned int remaining = MAX_TCP_OPTION_SPACE;

-#ifdef CONFIG_TCP_MD5SIG
- if (md5) {
+ if (tcp_key_is_md5(key)) {
opts->options |= OPTION_MD5;
remaining -= TCPOLEN_MD5SIG_ALIGNED;

@@ -906,8 +905,11 @@ static unsigned int tcp_synack_options(const struct sock *sk,
*/
if (synack_type != TCP_SYNACK_COOKIE)
ireq->tstamp_ok &= !ireq->sack_ok;
+ } else if (tcp_key_is_ao(key)) {
+ opts->options |= OPTION_AO;
+ remaining -= tcp_ao_len(key->ao_key);
+ ireq->tstamp_ok &= !ireq->sack_ok;
}
-#endif

/* We always send an MSS option. */
opts->mss = mss;
@@ -3655,7 +3657,6 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
{
struct inet_request_sock *ireq = inet_rsk(req);
const struct tcp_sock *tp = tcp_sk(sk);
- struct tcp_md5sig_key *md5 = NULL;
struct tcp_out_options opts;
struct tcp_key key = {};
struct sk_buff *skb;
@@ -3707,18 +3708,48 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb);
}

-#ifdef CONFIG_TCP_MD5SIG
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
rcu_read_lock();
- md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req));
- if (md5)
- key.type = TCP_KEY_MD5;
#endif
+ if (tcp_rsk_used_ao(req)) {
+#ifdef CONFIG_TCP_AO
+ struct tcp_ao_key *ao_key = NULL;
+ u8 maclen = tcp_rsk(req)->maclen;
+ u8 keyid = tcp_rsk(req)->ao_keyid;
+
+ ao_key = tcp_sk(sk)->af_specific->ao_lookup(sk, req_to_sk(req),
+ keyid, -1);
+ /* If there is no matching key - avoid sending anything,
+ * especially usigned segments. It could try harder and lookup
+ * for another peer-matching key, but the peer has requested
+ * ao_keyid (RFC5925 RNextKeyID), so let's keep it simple here.
+ */
+ if (unlikely(!ao_key || tcp_ao_maclen(ao_key) != maclen)) {
+ u8 key_maclen = ao_key ? tcp_ao_maclen(ao_key) : 0;
+
+ rcu_read_unlock();
+ kfree_skb(skb);
+ net_warn_ratelimited("TCP-AO: the keyid %u with maclen %u|%u from SYN packet is not present - not sending SYNACK\n",
+ keyid, maclen, key_maclen);
+ return NULL;
+ }
+ key.ao_key = ao_key;
+ key.type = TCP_KEY_AO;
+#endif
+ } else {
+#ifdef CONFIG_TCP_MD5SIG
+ key.md5_key = tcp_rsk(req)->af_specific->req_md5_lookup(sk,
+ req_to_sk(req));
+ if (key.md5_key)
+ key.type = TCP_KEY_MD5;
+#endif
+ }
skb_set_hash(skb, READ_ONCE(tcp_rsk(req)->txhash), PKT_HASH_TYPE_L4);
/* bpf program will be interested in the tcp_flags */
TCP_SKB_CB(skb)->tcp_flags = TCPHDR_SYN | TCPHDR_ACK;
- tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5,
- foc, synack_type,
- syn_skb) + sizeof(*th);
+ tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts,
+ &key, foc, synack_type, syn_skb)
+ + sizeof(*th);

skb_push(skb, tcp_header_size);
skb_reset_transport_header(skb);
@@ -3738,15 +3769,24 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,

/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
th->window = htons(min(req->rsk_rcv_wnd, 65535U));
- tcp_options_write(th, NULL, NULL, &opts, &key);
+ tcp_options_write(th, NULL, tcp_rsk(req), &opts, &key);
th->doff = (tcp_header_size >> 2);
TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS);

-#ifdef CONFIG_TCP_MD5SIG
/* Okay, we have all we need - do the md5 hash if needed */
- if (md5)
+ if (tcp_key_is_md5(&key)) {
+#ifdef CONFIG_TCP_MD5SIG
tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
- md5, req_to_sk(req), skb);
+ key.md5_key, req_to_sk(req), skb);
+#endif
+ } else if (tcp_key_is_ao(&key)) {
+#ifdef CONFIG_TCP_AO
+ tcp_rsk(req)->af_specific->ao_synack_hash(opts.hash_location,
+ key.ao_key, req, skb,
+ opts.hash_location - (u8 *)th, 0);
+#endif
+ }
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
rcu_read_unlock();
#endif

diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c
index c9a6fa84f6ce..99753e12c08c 100644
--- a/net/ipv6/tcp_ao.c
+++ b/net/ipv6/tcp_ao.c
@@ -144,3 +144,25 @@ int tcp_v6_parse_ao(struct sock *sk, int cmd,
{
return tcp_parse_ao(sk, cmd, AF_INET6, optval, optlen);
}
+
+int tcp_v6_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key,
+ struct request_sock *req, const struct sk_buff *skb,
+ int hash_offset, u32 sne)
+{
+ void *hash_buf = NULL;
+ int err;
+
+ hash_buf = kmalloc(tcp_ao_digest_size(ao_key), GFP_ATOMIC);
+ if (!hash_buf)
+ return -ENOMEM;
+
+ err = tcp_v6_ao_calc_key_rsk(ao_key, hash_buf, req);
+ if (err)
+ goto out;
+
+ err = tcp_ao_hash_skb(AF_INET6, ao_hash, ao_key, req_to_sk(req), skb,
+ hash_buf, hash_offset, sne);
+out:
+ kfree(hash_buf);
+ return err;
+}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 7d8dcbfe09ea..05d9ded5a413 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -838,6 +838,7 @@ const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
#ifdef CONFIG_TCP_AO
.ao_lookup = tcp_v6_ao_lookup_rsk,
.ao_calc_key = tcp_v6_ao_calc_key_rsk,
+ .ao_synack_hash = tcp_v6_ao_synack_hash,
#endif
#ifdef CONFIG_SYN_COOKIES
.cookie_init_seq = cookie_v6_init_sequence,
--
2.42.0

2023-10-09 23:13:02

by Dmitry Safonov

Subject: [PATCH v14 net-next 23/23] Documentation/tcp: Add TCP-AO documentation

It has Frequently Asked Questions (FAQ) on RFC 5925 - I found it very
useful answering those before writing the actual code. It provides answers
to common questions that arise on a quick read of the RFC, as well as how
they were answered. There's also comparison to TCP-MD5 option,
evaluation of per-socket vs in-kernel-DB approaches and description of
uAPI provided.

Hopefully, it will be as useful for reviewing the code as it was for writing.

Cc: Jonathan Corbet <[email protected]>
Cc: [email protected]
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
Documentation/networking/index.rst | 1 +
Documentation/networking/tcp_ao.rst | 444 ++++++++++++++++++++++++++++
2 files changed, 445 insertions(+)
create mode 100644 Documentation/networking/tcp_ao.rst

diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index 5b75c3f7a137..69c1e53ef88b 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -107,6 +107,7 @@ Contents:
sysfs-tagging
tc-actions-env-rules
tc-queue-filters
+ tcp_ao
tcp-thin
team
timestamping
diff --git a/Documentation/networking/tcp_ao.rst b/Documentation/networking/tcp_ao.rst
new file mode 100644
index 000000000000..cfa5bf1cc542
--- /dev/null
+++ b/Documentation/networking/tcp_ao.rst
@@ -0,0 +1,444 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========================================================
+TCP Authentication Option Linux implementation (RFC5925)
+========================================================
+
+TCP Authentication Option (TCP-AO) provides a TCP extension aimed at verifying
+segments between trusted peers. It adds a new TCP header option with
+a Message Authentication Code (MAC). MACs are produced from the content
+of a TCP segment using a hashing function with a password known to both peers.
+The intent of TCP-AO is to deprecate TCP-MD5 providing better security,
+key rotation and support for variety of hashing algorithms.
+
+1. Introduction
+===============
+
+.. table:: Short and Limited Comparison of TCP-AO and TCP-MD5
+
+ +----------------------+------------------------+-----------------------+
+ | | TCP-MD5 | TCP-AO |
+ +======================+========================+=======================+
+ |Supported hashing |MD5 |Must support HMAC-SHA1 |
+ |algorithms |(cryptographically weak)|(chosen-prefix attacks)|
+ | | |and CMAC-AES-128 (only |
+ | | |side-channel attacks). |
+ | | |May support any hashing|
+ | | |algorithm. |
+ +----------------------+------------------------+-----------------------+
+ |Length of MACs (bytes)|16 |Typically 12-16. |
+ | | |Other variants that fit|
+ | | |TCP header permitted. |
+ +----------------------+------------------------+-----------------------+
+ |Number of keys per |1 |Many |
+ |TCP connection | | |
+ +----------------------+------------------------+-----------------------+
+ |Possibility to change |Non-practical (both |Supported by protocol |
+ |an active key |peers have to change | |
+ | |them during MSL) | |
+ +----------------------+------------------------+-----------------------+
+ |Protection against |No |Yes: ignoring them |
+ |ICMP 'hard errors' | |by default on |
+ | | |established connections|
+ +----------------------+------------------------+-----------------------+
+ |Protection against |No |Yes: pseudo-header |
+ |traffic-crossing | |includes TCP ports. |
+ |attack | | |
+ +----------------------+------------------------+-----------------------+
+ |Protection against |No |Sequence Number |
+ |replayed TCP segments | |Extension (SNE) and |
+ | | |Initial Sequence |
+ | | |Numbers (ISNs) |
+ +----------------------+------------------------+-----------------------+
+ |Supports |Yes |No. ISNs+SNE are needed|
+ |Connectionless Resets | |to correctly sign RST. |
+ +----------------------+------------------------+-----------------------+
+ |Standards |RFC 2385 |RFC 5925, RFC 5926 |
+ +----------------------+------------------------+-----------------------+
+
+
+1.1 Frequently Asked Questions (FAQ) with references to RFC 5925
+----------------------------------------------------------------
+
+Q: Can either SendID or RecvID be non-unique for the same 4-tuple
+(srcaddr, srcport, dstaddr, dstport)?
+
+A: No [3.1]::
+
+ >> The IDs of MKTs MUST NOT overlap where their TCP connection
+ identifiers overlap.
+
+Q: Can Master Key Tuple (MKT) for an active connection be removed?
+
+A: No, unless it's copied to Transport Control Block (TCB) [3.1]::
+
+ It is presumed that an MKT affecting a particular connection cannot
+ be destroyed during an active connection -- or, equivalently, that
+ its parameters are copied to an area local to the connection (i.e.,
+ instantiated) and so changes would affect only new connections.
+
+Q: If an old MKT needs to be deleted, how should it be done in order
+to not remove it for an active connection? (As it can be still in use
+at any moment later)
+
+A: Not specified by RFC 5925, seems to be a problem for key management
+to ensure that no one uses such MKT before trying to remove it.
+
+Q: Can an old MKT exist forever and be used by another peer?
+
+A: It can, it's a key management task to decide when to remove an old key [6.1]::
+
+ Deciding when to start using a key is a performance issue. Deciding
+ when to remove an MKT is a security issue. Invalid MKTs are expected
+ to be removed. TCP-AO provides no mechanism to coordinate their removal,
+ as we consider this a key management operation.
+
+also [6.1]::
+
+ The only way to avoid reuse of previously used MKTs is to remove the MKT
+ when it is no longer considered permitted.
+
+Linux TCP-AO will try its best to prevent you from removing a key that's
+being used, considering it a key management failure. But sine keeping
+an outdated key may become a security issue and as a peer may
+unintentionally prevent the removal of an old key by always setting
+it as RNextKeyID - a forced key removal mechanism is provided, where
+userspace has to supply KeyID to use instead of the one that's being removed
+and the kernel will atomically delete the old key, even if the peer is
+still requesting it. There are no guarantees for force-delete as the peer
+may yet not have the new key - the TCP connection may just break.
+Alternatively, one may choose to shut down the socket.
+
+Q: What happens when a packet is received on a new connection with no known
+MKT's RecvID?
+
+A: RFC 5925 specifies that by default it is accepted with a warning logged, but
+the behaviour can be configured by the user [7.5.1.a]::
+
+ If the segment is a SYN, then this is the first segment of a new
+ connection. Find the matching MKT for this segment, using the segment's
+ socket pair and its TCP-AO KeyID, matched against the MKT's TCP connection
+ identifier and the MKT's RecvID.
+
+ i. If there is no matching MKT, remove TCP-AO from the segment.
+ Proceed with further TCP handling of the segment.
+ NOTE: this presumes that connections that do not match any MKT
+ should be silently accepted, as noted in Section 7.3.
+
+[7.3]::
+
+ >> A TCP-AO implementation MUST allow for configuration of the behavior
+ of segments with TCP-AO but that do not match an MKT. The initial default
+ of this configuration SHOULD be to silently accept such connections.
+ If this is not the desired case, an MKT can be included to match such
+ connections, or the connection can indicate that TCP-AO is required.
+ Alternately, the configuration can be changed to discard segments with
+ the AO option not matching an MKT.
+
+[10.2.b]::
+
+ Connections not matching any MKT do not require TCP-AO. Further, incoming
+ segments with TCP-AO are not discarded solely because they include
+ the option, provided they do not match any MKT.
+
+Note that Linux TCP-AO implementation differs in this aspect. Currently, TCP-AO
+segments with unknown key signatures are discarded with warnings logged.
+
+Q: Does the RFC imply centralized kernel key management in any way?
+(i.e. that a key on all connections MUST be rotated at the same time?)
+
+A: Not specified. MKTs can be managed in userspace, the only relevant part to
+key changes is [7.3]::
+
+ >> All TCP segments MUST be checked against the set of MKTs for matching
+ TCP connection identifiers.
+
+Q: What happens when RNextKeyID requested by a peer is unknown? Should
+the connection be reset?
+
+A: It should not, no action needs to be performed [7.5.2.e]::
+
+ ii. If they differ, determine whether the RNextKeyID MKT is ready.
+
+ 1. If the MKT corresponding to the segment’s socket pair and RNextKeyID
+ is not available, no action is required (RNextKeyID of a received
+ segment needs to match the MKT’s SendID).
+
+Q: How current_key is set and when does it change? It is a user-triggered
+change, or is it by a request from the remote peer? Is it set by the user
+explicitly, or by a matching rule?
+
+A: current_key is set by RNextKeyID [6.1]::
+
+ Rnext_key is changed only by manual user intervention or MKT management
+ protocol operation. It is not manipulated by TCP-AO. Current_key is updated
+ by TCP-AO when processing received TCP segments as discussed in the segment
+ processing description in Section 7.5. Note that the algorithm allows
+ the current_key to change to a new MKT, then change back to a previously
+ used MKT (known as "backing up"). This can occur during an MKT change when
+ segments are received out of order, and is considered a feature of TCP-AO,
+ because reordering does not result in drops.
+
+[7.5.2.e.ii]::
+
+ 2. If the matching MKT corresponding to the segment’s socket pair and
+ RNextKeyID is available:
+
+ a. Set current_key to the RNextKeyID MKT.
+
+Q: If both peers have multiple MKTs matching the connection's socket pair
+(with different KeyIDs), how should the sender/receiver pick KeyID to use?
+
+A: Some mechanism should pick the "desired" MKT [3.3]::
+
+ Multiple MKTs may match a single outgoing segment, e.g., when MKTs
+ are being changed. Those MKTs cannot have conflicting IDs (as noted
+ elsewhere), and some mechanism must determine which MKT to use for each
+ given outgoing segment.
+
+ >> An outgoing TCP segment MUST match at most one desired MKT, indicated
+ by the segment’s socket pair. The segment MAY match multiple MKTs, provided
+ that exactly one MKT is indicated as desired. Other information in
+ the segment MAY be used to determine the desired MKT when multiple MKTs
+ match; such information MUST NOT include values in any TCP option fields.
+
+Q: Can TCP-MD5 connection migrate to TCP-AO (and vice-versa):
+
+A: No [1]::
+
+ TCP MD5-protected connections cannot be migrated to TCP-AO because TCP MD5
+ does not support any changes to a connection’s security algorithm
+ once established.
+
+Q: If all MKTs are removed on a connection, can it become a non-TCP-AO signed
+connection?
+
+A: [7.5.2] doesn't have the same choice as SYN packet handling in [7.5.1.i]
+that would allow accepting segments without a sign (which would be insecure).
+While switching to non-TCP-AO connection is not prohibited directly, it seems
+what the RFC means. Also, there's a requirement for TCP-AO connections to
+always have one current_key [3.3]::
+
+ TCP-AO requires that every protected TCP segment match exactly one MKT.
+
+[3.3]::
+
+ >> An incoming TCP segment including TCP-AO MUST match exactly one MKT,
+ indicated solely by the segment’s socket pair and its TCP-AO KeyID.
+
+[4.4]::
+
+ One or more MKTs. These are the MKTs that match this connection’s
+ socket pair.
+
+Q: Can a non-TCP-AO connection become a TCP-AO-enabled one?
+
+A: No: for already established non-TCP-AO connection it would be impossible
+to switch using TCP-AO as the traffic key generation requires the initial
+sequence numbers. Paraphrasing, starting using TCP-AO would require
+re-establishing the TCP connection.
+
+2. In-kernel MKTs database vs database in userspace
+===================================================
+
+Linux TCP-AO support is implemented using ``setsockopt()s``, in a similar way
+to TCP-MD5. It means that a userspace application that wants to use TCP-AO
+should perform ``setsockopt()`` on a TCP socket when it wants to add,
+remove or rotate MKTs. This approach moves the key management responsibility
+to userspace as well as decisions on corner cases, i.e. what to do if
+the peer doesn't respect RNextKeyID; moving more code to userspace, especially
+responsible for the policy decisions. Besides, it's flexible and scales well
+(with less locking needed than in the case of an in-kernel database). One also
+should keep in mind that mainly intended users are BGP processes, not any
+random applications, which means that compared to IPsec tunnels,
+no transparency is really needed and modern BGP daemons already have
+``setsockopt()s`` for TCP-MD5 support.
+
+.. table:: Considered pros and cons of the approaches
+
+ +----------------------+------------------------+-----------------------+
+ | | ``setsockopt()`` | in-kernel DB |
+ +======================+========================+=======================+
+ | Extendability | ``setsockopt()`` | Netlink messages are |
+ | | commands should be | simple and extendable |
+ | | extendable syscalls | |
+ +----------------------+------------------------+-----------------------+
+ | Required userspace | BGP or any application | could be transparent |
+ | changes | that wants TCP-AO needs| as tunnels, providing |
+ | | to perform | something like |
+ | | ``setsockopt()s`` | ``ip tcpao add key`` |
+ | | and do key management | (delete/show/rotate) |
+ +----------------------+------------------------+-----------------------+
+ |MKTs removal or adding| harder for userspace | harder for kernel |
+ +----------------------+------------------------+-----------------------+
+ | Dump-ability | ``getsockopt()`` | Netlink .dump() |
+ | | | callback |
+ +----------------------+------------------------+-----------------------+
+ | Limits on kernel | equal |
+ | resources/memory | |
+ +----------------------+------------------------+-----------------------+
+ | Scalability | contention on | contention on |
+ | | ``TCP_LISTEN`` sockets | the whole database |
+ +----------------------+------------------------+-----------------------+
+ | Monitoring & warnings| ``TCP_DIAG`` | same Netlink socket |
+ +----------------------+------------------------+-----------------------+
+ | Matching of MKTs | half-problem: only | hard |
+ | | listen sockets | |
+ +----------------------+------------------------+-----------------------+
+
+
+3. uAPI
+=======
+
+Linux provides a set of ``setsockopt()s`` and ``getsockopt()s`` that let
+userspace manage TCP-AO on a per-socket basis. In order to add/delete MKTs
+``TCP_AO_ADD_KEY`` and ``TCP_AO_DEL_KEY`` TCP socket options must be used
+It is not allowed to add a key on an established non-TCP-AO connection
+as well as to remove the last key from TCP-AO connection.
+
+``setsockopt(TCP_AO_DEL_KEY)`` command may specify ``tcp_ao_del::current_key``
++ ``tcp_ao_del::set_current`` and/or ``tcp_ao_del::rnext``
++ ``tcp_ao_del::set_rnext`` which makes such delete "forced": it
+provides userspace a way to delete a key that's being used and atomically set
+another one instead. This is not intended for normal use and should be used
+only when the peer ignores RNextKeyID and keeps requesting/using an old key.
+It provides a way to force-delete a key that's not trusted but may break
+the TCP-AO connection.
+
+The usual/normal key-rotation can be performed with ``setsockopt(TCP_AO_INFO)``.
+It also provides a uAPI to change per-socket TCP-AO settings, such as
+ignoring ICMPs, as well as clear per-socket TCP-AO packet counters.
+The corresponding ``getsockopt(TCP_AO_INFO)`` can be used to get those
+per-socket TCP-AO settings.
+
+Another useful command is ``getsockopt(TCP_AO_GET_KEYS)``. One can use it
+to list all MKTs on a TCP socket or use a filter to get keys for a specific
+peer and/or sndid/rcvid, VRF L3 interface or get current_key/rnext_key.
+
+To repair TCP-AO connections ``setsockopt(TCP_AO_REPAIR)`` is available,
+provided that the user previously has checkpointed/dumped the socket with
+``getsockopt(TCP_AO_REPAIR)``.
+
+A tip here for scaled TCP_LISTEN sockets, that may have some thousands TCP-AO
+keys, is: use filters in ``getsockopt(TCP_AO_GET_KEYS)`` and asynchronous
+delete with ``setsockopt(TCP_AO_DEL_KEY)``.
+
+Linux TCP-AO also provides a bunch of segment counters that can be helpful
+with troubleshooting/debugging issues. Every MKT has good/bad counters
+that reflect how many packets passed/failed verification.
+Each TCP-AO socket has the following counters:
+- for good segments (properly signed)
+- for bad segments (failed TCP-AO verification)
+- for segments with unknown keys
+- for segments where an AO signature was expected, but wasn't found
+- for the number of ignored ICMPs
+
+TCP-AO per-socket counters are also duplicated with per-netns counters,
+exposed with SNMP. Those are ``TCPAOGood``, ``TCPAOBad``, ``TCPAOKeyNotFound``,
+``TCPAORequired`` and ``TCPAODroppedIcmps``.
+
+RFC 5925 very permissively specifies how TCP port matching can be done for
+MKTs::
+
+ TCP connection identifier. A TCP socket pair, i.e., a local IP
+ address, a remote IP address, a TCP local port, and a TCP remote port.
+ Values can be partially specified using ranges (e.g., 2-30), masks
+ (e.g., 0xF0), wildcards (e.g., "*"), or any other suitable indication.
+
+Currently Linux TCP-AO implementation doesn't provide any TCP port matching.
+Probably, port ranges are the most flexible for uAPI, but so far
+not implemented.
+
+4. ``setsockopt()`` vs ``accept()`` race
+========================================
+
+In contrast with TCP-MD5 established connection which has just one key,
+TCP-AO connections may have many keys, which means that accepted connections
+on a listen socket may have any amount of keys as well. As copying all those
+keys on a first properly signed SYN would make the request socket bigger, that
+would be undesirable. Currently, the implementation doesn't copy keys
+to request sockets, but rather look them up on the "parent" listener socket.
+
+The result is that when userspace removes TCP-AO keys, that may break
+not-yet-established connections on request sockets as well as not removing
+keys from sockets that were already established, but not yet ``accept()``'ed,
+hanging in the accept queue.
+
+The reverse is valid as well: if userspace adds a new key for a peer on
+a listener socket, the established sockets in accept queue won't
+have the new keys.
+
+At this moment, the resolution for the two races:
+``setsockopt(TCP_AO_ADD_KEY)`` vs ``accept()``
+and ``setsockopt(TCP_AO_DEL_KEY)`` vs ``accept()`` is delegated to userspace.
+This means that it's expected that userspace would check the MKTs on the socket
+that was returned by ``accept()`` to verify that any key rotation that
+happened on listen socket is reflected on the newly established connection.
+
+This is a similar "do-nothing" approach to TCP-MD5 from the kernel side and
+may be changed later by introducing new flags to ``tcp_ao_add``
+and ``tcp_ao_del``.
+
+Note that this race is rare for it needs TCP-AO key rotation to happen
+during the 3-way handshake for the new TCP connection.
+
+5. Interaction with TCP-MD5
+===========================
+
+A TCP connection can not migrate between TCP-AO and TCP-MD5 options. The
+established sockets that have either AO or MD5 keys are restricted for
+adding keys of the other option.
+
+For listening sockets the picture is different: BGP server may want to receive
+both TCP-AO and (deprecated) TCP-MD5 clients. As a result, both types of keys
+may be added to TCP_CLOSED or TCP_LISTEN sockets. It's not allowed to add
+different types of keys for the same peer.
+
+6. SNE Linux implementation
+===========================
+
+RFC 5925 [6.2] describes the algorithm of how to extend TCP sequence numbers
+with SNE. In short: TCP has to track the previous sequence numbers and set
+sne_flag when the current SEQ number rolls over. The flag is cleared when
+both current and previous SEQ numbers cross 0x7fff, which is 32Kb.
+
+In times when sne_flag is set, the algorithm compares SEQ for each packet with
+0x7fff and if it's higher than 32Kb, it assumes that the packet should be
+verified with SNE before the increment. As a result, there's
+this [0; 32Kb] window, when packets with (SNE - 1) can be accepted.
+
+Linux implementation simplifies this a bit: as the network stack already tracks
+the first SEQ byte that ACK is wanted for (snd_una) and the next SEQ byte that
+is wanted (rcv_nxt) - that's enough information for a rough estimation
+on where in the 4GB SEQ number space both sender and receiver are.
+When they roll over to zero, the corresponding SNE gets incremented.
+
+tcp_ao_compute_sne() is called for each TCP-AO segment. It compares SEQ numbers
+from the segment with snd_una or rcv_nxt and fits the result into a 2GB window around them,
+detecting SEQ numbers rolling over. That simplifies the code a lot and only
+requires SNE numbers to be stored on every TCP-AO socket.
+
+The 2GB window at first glance seems much more permissive compared to
+RFC 5926. But that is only used to pick the correct SNE before/after
+a rollover. It allows more TCP segment replays, but yet all regular
+TCP checks in tcp_sequence() are applied on the verified segment.
+So, it trades a bit more permissive acceptance of replayed/retransmitted
+segments for the simplicity of the algorithm and what seems better behaviour
+for large TCP windows.
+
+7. Links
+========
+
+RFC 5925 The TCP Authentication Option
+ https://www.rfc-editor.org/rfc/pdfrfc/rfc5925.txt.pdf
+
+RFC 5926 Cryptographic Algorithms for the TCP Authentication Option (TCP-AO)
+ https://www.rfc-editor.org/rfc/pdfrfc/rfc5926.txt.pdf
+
+Draft "SHA-2 Algorithm for the TCP Authentication Option (TCP-AO)"
+ https://datatracker.ietf.org/doc/html/draft-nayak-tcp-sha2-03
+
+RFC 2385 Protection of BGP Sessions via the TCP MD5 Signature Option
+ https://www.rfc-editor.org/rfc/pdfrfc/rfc2385.txt.pdf
+
+:Author: Dmitry Safonov <[email protected]>
--
2.42.0

2023-10-09 23:13:20

by Dmitry Safonov

Subject: [PATCH v14 net-next 19/23] net/tcp: Allow asynchronous delete for TCP-AO keys (MKTs)

Delete becomes very, very fast - almost free, but after setsockopt()
syscall returns, the key is still alive until next RCU grace period.
Which is fine for listen sockets as userspace needs to be aware of
setsockopt(TCP_AO) and accept() race and resolve it with verification
by getsockopt() after TCP connection was accepted.

The benchmark results (on non-loaded box, worse with more RCU work pending):
> ok 33 Worst case delete 16384 keys: min=5ms max=10ms mean=6.93904ms stddev=0.263421
> ok 34 Add a new key 16384 keys: min=1ms max=4ms mean=2.17751ms stddev=0.147564
> ok 35 Remove random-search 16384 keys: min=5ms max=10ms mean=6.50243ms stddev=0.254999
> ok 36 Remove async 16384 keys: min=0ms max=0ms mean=0.0296107ms stddev=0.0172078

Co-developed-by: Francesco Ruggeri <[email protected]>
Signed-off-by: Francesco Ruggeri <[email protected]>
Co-developed-by: Salam Noureddine <[email protected]>
Signed-off-by: Salam Noureddine <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Acked-by: David Ahern <[email protected]>
---
include/uapi/linux/tcp.h | 3 ++-
net/ipv4/tcp_ao.c | 21 ++++++++++++++++++---
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index a411aef00318..25d62ecb9532 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -395,7 +395,8 @@ struct tcp_ao_del { /* setsockopt(TCP_AO_DEL_KEY) */
__s32 ifindex; /* L3 dev index for VRF */
__u32 set_current :1, /* corresponding ::current_key */
set_rnext :1, /* corresponding ::rnext */
- reserved :30; /* must be 0 */
+ del_async :1, /* only valid for listen sockets */
+ reserved :29; /* must be 0 */
__u16 reserved2; /* padding, must be 0 */
__u8 prefix; /* peer's address prefix */
__u8 sndid; /* SendID for outgoing segments */
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 5962df17ecbe..afd5943a9972 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -1625,7 +1625,7 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
}

static int tcp_ao_delete_key(struct sock *sk, struct tcp_ao_info *ao_info,
- struct tcp_ao_key *key,
+ bool del_async, struct tcp_ao_key *key,
struct tcp_ao_key *new_current,
struct tcp_ao_key *new_rnext)
{
@@ -1633,11 +1633,24 @@ static int tcp_ao_delete_key(struct sock *sk, struct tcp_ao_info *ao_info,

hlist_del_rcu(&key->node);

+ /* Support for async delete on listening sockets: as they don't
+ * need current_key/rnext_key maintaining, we don't need to check
+ * them and we can just free all resources in RCU fashion.
+ */
+ if (del_async) {
+ atomic_sub(tcp_ao_sizeof_key(key), &sk->sk_omem_alloc);
+ call_rcu(&key->rcu, tcp_ao_key_free_rcu);
+ return 0;
+ }
+
/* At this moment another CPU could have looked this key up
* while it was unlinked from the list. Wait for RCU grace period,
* after which the key is off-list and can't be looked up again;
* the rx path [just before RCU came] might have used it and set it
* as current_key (very unlikely).
+ * Free the key with next RCU grace period (in case it was
+ * current_key before tcp_ao_current_rnext() might have
+ * changed it in forced-delete).
*/
synchronize_rcu();
if (new_current)
@@ -1708,6 +1721,8 @@ static int tcp_ao_del_cmd(struct sock *sk, unsigned short int family,
if (!new_rnext)
return -ENOENT;
}
+ if (cmd.del_async && sk->sk_state != TCP_LISTEN)
+ return -EINVAL;

if (family == AF_INET) {
struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.addr;
@@ -1755,8 +1770,8 @@ static int tcp_ao_del_cmd(struct sock *sk, unsigned short int family,
if (key == new_current || key == new_rnext)
continue;

- return tcp_ao_delete_key(sk, ao_info, key,
- new_current, new_rnext);
+ return tcp_ao_delete_key(sk, ao_info, cmd.del_async, key,
+ new_current, new_rnext);
}
return -ENOENT;
}
--
2.42.0