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From:   Dmitry Safonov <dima@arista.com>
To:     Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        linux-kernel@vger.kernel.org
Cc:     Dmitry Safonov <dima@arista.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Ard Biesheuvel <ardb@kernel.org>,
        Bob Gilligan <gilligan@arista.com>,
        David Ahern <dsahern@kernel.org>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Francesco Ruggeri <fruggeri@arista.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Ivan Delalande <colona@arista.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Leonard Crestez <cdleonard@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Salam Noureddine <noureddine@arista.com>,
        Shuah Khan <shuah@kernel.org>, netdev@vger.kernel.org,
        linux-crypto@vger.kernel.org
Subject: [PATCH 22/31] net/tcp: Add option for TCP-AO to (not) hash header
Date:   Thu, 18 Aug 2022 17:59:56 +0100
Message-Id: <20220818170005.747015-23-dima@arista.com>
In-Reply-To: <20220818170005.747015-1-dima@arista.com>
References: <20220818170005.747015-1-dima@arista.com>
MIME-Version: 1.0
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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 | 2 ++
 net/ipv4/tcp_ao.c        | 8 +++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 508bedbc6ad8..b60933ee2a27 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -347,6 +347,8 @@ struct tcp_diag_md5sig {
 
 #define TCP_AO_MAXKEYLEN	80
 
+#define TCP_AO_KEYF_EXCLUDE_OPT	(1 << 0)
+
 #define TCP_AO_CMDF_CURR	(1 << 0)	/* Only checks field sndid */
 #define TCP_AO_CMDF_NEXT	(1 << 1)	/* Only checks field rcvid */
 #define TCP_AO_CMDF_ACCEPT_ICMP	(1 << 2)	/* Accept incoming ICMPs */
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 858295393643..6e18a8cdee90 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -586,7 +586,8 @@ int tcp_ao_hash_hdr(unsigned short int family, char *ao_hash,
 						&saddr->a6, th->doff * 4))
 			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, ao_hash, 0);
@@ -628,7 +629,8 @@ 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_ao_hash_skb_data(&hp, skb, th->doff << 2))
@@ -1416,7 +1418,7 @@ static bool tcp_ao_mkt_overlap_v6(struct tcp_ao *cmd,
 	return false;
 }
 
-#define TCP_AO_KEYF_ALL		(0)
+#define TCP_AO_KEYF_ALL		(TCP_AO_KEYF_EXCLUDE_OPT)
 #define TCP_AO_CMDF_ADDMOD_VALID					\
 	(TCP_AO_CMDF_CURR | TCP_AO_CMDF_NEXT | TCP_AO_CMDF_ACCEPT_ICMP)
 #define TCP_AO_CMDF_DEL_VALID						\
-- 
2.37.2