netdev - [PATCH v4 17/21] net/tcp: Add option for TCP-AO to (not) hash header

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Message-Id: <20230215183335.800122-18-dima@arista.com>
Date:   Wed, 15 Feb 2023 18:33:31 +0000
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Dmitry Safonov <dima@...sta.com>,
        Andy Lutomirski <luto@...capital.net>,
        Ard Biesheuvel <ardb@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        David Laight <David.Laight@...lab.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Eric Biggers <ebiggers@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Francesco Ruggeri <fruggeri05@...il.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Ivan Delalande <colona@...sta.com>,
        Leonard Crestez <cdleonard@...il.com>,
        Salam Noureddine <noureddine@...sta.com>,
        netdev@...r.kernel.org, Francesco Ruggeri <fruggeri@...sta.com>
Subject: [PATCH v4 17/21] 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 <fruggeri@...sta.com>
Signed-off-by: Francesco Ruggeri <fruggeri@...sta.com>
Co-developed-by: Salam Noureddine <noureddine@...sta.com>
Signed-off-by: Salam Noureddine <noureddine@...sta.com>
Signed-off-by: Dmitry Safonov <dima@...sta.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 6c8b4dcc51ee..323ee886634f 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"
+						 */
 
 #define TCP_AO_CMDF_CURR	(1 << 0)	/* Only checks field sndid */
 #define TCP_AO_CMDF_NEXT	(1 << 1)	/* Only checks field rcvid */
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 07935e8a1066..d335023a1619 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -589,7 +589,8 @@ 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, ao_hash, 0);
@@ -631,7 +632,8 @@ 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))
@@ -1498,7 +1500,7 @@ static inline bool tcp_ao_mkt_overlap_v6(struct tcp_ao *cmd,
 }
 #endif
 
-#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						\
-- 
2.39.1