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[v13,net-next,17/23] net/tcp: Add option for TCP-AO to (not) hash header

Message ID 20231004223629.166300-18-dima@arista.com
State New
Headers
Series [v13,net-next,01/23] net/tcp: Prepare tcp_md5sig_pool for TCP-AO |

Commit Message

Dmitry Safonov Oct. 4, 2023, 10:36 p.m. UTC 
  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>
Acked-by: David Ahern <dsahern@kernel.org>
---
 include/uapi/linux/tcp.h | 5 +++++
 net/ipv4/tcp_ao.c        | 8 +++++---
 2 files changed, 10 insertions(+), 3 deletions(-)
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Patch

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)