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From:   Dmitry Safonov <dima@arista.com>
To:     David Ahern <dsahern@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "David S. Miller" <davem@davemloft.net>
Cc:     linux-kernel@vger.kernel.org, Dmitry Safonov <dima@arista.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Ard Biesheuvel <ardb@kernel.org>,
        Bob Gilligan <gilligan@arista.com>,
        Dan Carpenter <error27@gmail.com>,
        David Laight <David.Laight@aculab.com>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Donald Cassidy <dcassidy@redhat.com>,
        Eric Biggers <ebiggers@kernel.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Francesco Ruggeri <fruggeri05@gmail.com>,
        "Gaillardetz, Dominik" <dgaillar@ciena.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Ivan Delalande <colona@arista.com>,
        Leonard Crestez <cdleonard@gmail.com>,
        Salam Noureddine <noureddine@arista.com>,
        "Tetreault, Francois" <ftetreau@ciena.com>, netdev@vger.kernel.org
Subject: [PATCH v8.1 net-next 17/23] net/tcp: Add option for TCP-AO to (not) hash header
Date:   Fri, 21 Jul 2023 17:19:08 +0100
Message-ID: <20230721161916.542667-18-dima@arista.com>
In-Reply-To: <20230721161916.542667-1-dima@arista.com>
References: <20230721161916.542667-1-dima@arista.com>
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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 <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 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 ca7ed18ce67b..3275ade3293a 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -354,6 +354,11 @@ 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 4bde58ede63a..4fabd3ec5c71 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -567,7 +567,8 @@ 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);
@@ -615,7 +616,8 @@ 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))
@@ -1430,7 +1432,7 @@ 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)
-- 
2.41.0