In tcp_create_openreq_child we adjust tcp_header_len for md5 using the
remote address in newsk. But that address is still 0 in newsk at this
point, and it is only set later by the callers (tcp_v[46]_syn_recv_sock).
Use the address from the request socket instead.
v2: Added "Fixes:" line.
Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")
Signed-off-by: Francesco Ruggeri <[email protected]>
---
net/ipv4/tcp_minisocks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6366df7aaf2a..6854bb1fb32b 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -531,7 +531,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
newtp->tsoffset = treq->ts_off;
#ifdef CONFIG_TCP_MD5SIG
newtp->md5sig_info = NULL; /*XXX*/
- if (newtp->af_specific->md5_lookup(sk, newsk))
+ if (treq->af_specific->req_md5_lookup(sk, req_to_sk(req)))
newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
#endif
if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
--
2.28.0
Hello:
This patch was applied to netdev/net.git (master)
by Jakub Kicinski <[email protected]>:
On Wed, 20 Apr 2022 17:50:26 -0700 you wrote:
> In tcp_create_openreq_child we adjust tcp_header_len for md5 using the
> remote address in newsk. But that address is still 0 in newsk at this
> point, and it is only set later by the callers (tcp_v[46]_syn_recv_sock).
> Use the address from the request socket instead.
>
> v2: Added "Fixes:" line.
>
> [...]
Here is the summary with links:
- [v2,net] tcp: md5: incorrect tcp_header_len for incoming connections
https://git.kernel.org/netdev/net/c/5b0b9e4c2c89
You are awesome, thank you!
--
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On Wed, Apr 20, 2022 at 5:50 PM Francesco Ruggeri <[email protected]> wrote:
>
> In tcp_create_openreq_child we adjust tcp_header_len for md5 using the
> remote address in newsk. But that address is still 0 in newsk at this
> point, and it is only set later by the callers (tcp_v[46]_syn_recv_sock).
> Use the address from the request socket instead.
>
> v2: Added "Fixes:" line.
>
> Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")
> Signed-off-by: Francesco Ruggeri <[email protected]>
> ---
> net/ipv4/tcp_minisocks.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
> index 6366df7aaf2a..6854bb1fb32b 100644
> --- a/net/ipv4/tcp_minisocks.c
> +++ b/net/ipv4/tcp_minisocks.c
> @@ -531,7 +531,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
> newtp->tsoffset = treq->ts_off;
> #ifdef CONFIG_TCP_MD5SIG
> newtp->md5sig_info = NULL; /*XXX*/
> - if (newtp->af_specific->md5_lookup(sk, newsk))
> + if (treq->af_specific->req_md5_lookup(sk, req_to_sk(req)))
Wait a minute.
Are you sure treq->af_specific is initialized at this point ?
I should have tested this one liner patch really :/
I think that for syncookies, treq->af_specific is not initialized,
because we do not go through
tcp_conn_request() helper, but instead use cookie_tcp_reqsk_alloc()
Before your patch treq->af_specific was only used during SYNACK
generation, which does not happen in syncookie more while receiving
the third packet.
I will test something like this patch. We could move the init after
cookie_tcp_reqsk_alloc() has been called, but I prefer using the same
construct than tcp_conn_request()
diff --git a/include/net/tcp.h b/include/net/tcp.h
index be712fb9ddd71b2b320356677f3aa1c6759e2698..9987b3fba9f202632916cc439af9d17f1e68bcd3
100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -480,6 +480,7 @@ int __cookie_v4_check(const struct iphdr *iph,
const struct tcphdr *th,
u32 cookie);
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
+ const struct
tcp_request_sock_ops *af_ops,
struct sock *sk, struct
sk_buff *skb);
#ifdef CONFIG_SYN_COOKIES
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 2cb3b852d14861231ac47f0b3e4daeb57682ffd2..f191bfa996d71f11ef786a0a3bcb8f737622d37a
100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -281,6 +281,7 @@ bool cookie_ecn_ok(const struct
tcp_options_received *tcp_opt,
EXPORT_SYMBOL(cookie_ecn_ok);
struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
+ const struct
tcp_request_sock_ops *af_ops,
struct sock *sk,
struct sk_buff *skb)
{
@@ -297,6 +298,8 @@ struct request_sock *cookie_tcp_reqsk_alloc(const
struct request_sock_ops *ops,
return NULL;
treq = tcp_rsk(req);
+ /* treq->af_specific might be used to perform TCP_MD5 lookup */
+ treq->af_specific = af_ops;
treq->syn_tos = TCP_SKB_CB(skb)->ip_dsfield;
#if IS_ENABLED(CONFIG_MPTCP)
treq->is_mptcp = sk_is_mptcp(sk);
@@ -364,7 +367,8 @@ struct sock *cookie_v4_check(struct sock *sk,
struct sk_buff *skb)
goto out;
ret = NULL;
- req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops, sk, skb);
+ req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops,
+ &tcp_request_sock_ipv4_ops, sk, skb);
if (!req)
goto out;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index d1b61d00368e1f58725e9997f74a0b144901277e..9cc123f000fbcfbeff7728bfee5339d6dd6470f9
100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -170,7 +170,8 @@ struct sock *cookie_v6_check(struct sock *sk,
struct sk_buff *skb)
goto out;
ret = NULL;
- req = cookie_tcp_reqsk_alloc(&tcp6_request_sock_ops, sk, skb);
+ req = cookie_tcp_reqsk_alloc(&tcp6_request_sock_ops,
+ &tcp_request_sock_ipv6_ops, sk, skb);
if (!req)
goto out;
On Sun, Apr 24, 2022 at 12:37 PM Eric Dumazet <[email protected]> wrote:
>
> Wait a minute.
>
> Are you sure treq->af_specific is initialized at this point ?
>
> I should have tested this one liner patch really :/
>
> I think that for syncookies, treq->af_specific is not initialized,
> because we do not go through
> tcp_conn_request() helper, but instead use cookie_tcp_reqsk_alloc()
>
> Before your patch treq->af_specific was only used during SYNACK
> generation, which does not happen in syncookie more while receiving
> the third packet.
>
> I will test something like this patch. We could move the init after
> cookie_tcp_reqsk_alloc() has been called, but I prefer using the same
> construct than tcp_conn_request()
>
Thanks for fixing this Eric. I had not considered syncookies.
Francesco