net/tcp: Wire up l3index to TCP-AO

Similarly how TCP_MD5SIG_FLAG_IFINDEX works for TCP-MD5,
TCP_AO_KEYF_IFINDEX is an AO-key flag that binds that MKT to a specified
by L3 ifinndex. Similarly, without this flag the key will work in
the default VRF l3index = 0 for connections.
To prevent AO-keys from overlapping, it's restricted to add key B for a
socket that has key A, which have the same sndid/rcvid and one of
the following is true:
- !(A.keyflags & TCP_AO_KEYF_IFINDEX) or !(B.keyflags & TCP_AO_KEYF_IFINDEX)
  so that any key is non-bound to a VRF
- A.l3index == B.l3index
  both want to work for the same VRF

Additionally, it's restricted to match TCP-MD5 keys for the same peer
the following way:
|--------------|--------------------|----------------|---------------|
|              | MD5 key without    |     MD5 key    |    MD5 key    |
|              |     l3index        |    l3index=0   |   l3index=N   |
|--------------|--------------------|----------------|---------------|
|  TCP-AO key  |                    |                |               |
|  without     |       reject       |    reject      |   reject      |
|  l3index     |                    |                |               |
|--------------|--------------------|----------------|---------------|
|  TCP-AO key  |                    |                |               |
|  l3index=0   |       reject       |    reject      |   allow       |
|--------------|--------------------|----------------|---------------|
|  TCP-AO key  |                    |                |               |
|  l3index=N   |       reject       |    allow       |   reject      |
|--------------|--------------------|----------------|---------------|

This is done with the help of tcp_md5_do_lookup_any_l3index() to reject
adding AO key without TCP_AO_KEYF_IFINDEX if there's TCP-MD5 in any VRF.
This is important for case where sysctl_tcp_l3mdev_accept = 1
Similarly, for TCP-AO lookups tcp_ao_do_lookup() may be used with
l3index < 0, so that __tcp_ao_key_cmp() will match TCP-AO key in any VRF.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 15 insertions, 14 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index e3617c433cf1..d2f0736b76b8 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2717,7 +2717,7 @@ static inline int tcp_parse_auth_options(const struct tcphdr *th,
 }
 
 static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
-				   int family, bool stat_inc)
+				   int family, int l3index, bool stat_inc)
 {
 #ifdef CONFIG_TCP_AO
 	struct tcp_ao_info *ao_info;
@@ -2731,7 +2731,7 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
 	if (!ao_info)
 		return false;
 
-	ao_key = tcp_ao_do_lookup(sk, saddr, family, -1, -1);
+	ao_key = tcp_ao_do_lookup(sk, l3index, saddr, family, -1, -1);
 	if (ao_info->ao_required || ao_key) {
 		if (stat_inc) {
 			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOREQUIRED);
@@ -2784,21 +2784,22 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
 		 * the last key is impossible to remove, so there's
 		 * always at least one current_key.
 		 */
-		if (tcp_ao_required(sk, saddr, family, true)) {
+		if (tcp_ao_required(sk, saddr, family, l3index, true)) {
 			tcp_hash_fail("AO hash is required, but not found",
 					family, skb, "L3 index %d", l3index);
 			return SKB_DROP_REASON_TCP_AONOTFOUND;
 		}
 		if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) {
 			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
-			tcp_hash_fail("MD5 Hash not found", family, skb, "");
+			tcp_hash_fail("MD5 Hash not found",
+				      family, skb, "L3 index %d", l3index);
 			return SKB_DROP_REASON_TCP_MD5NOTFOUND;
 		}
 		return SKB_NOT_DROPPED_YET;
 	}
 
 	if (aoh)
-		return tcp_inbound_ao_hash(sk, skb, family, req, aoh);
+		return tcp_inbound_ao_hash(sk, skb, family, req, l3index, aoh);
 
 	return tcp_inbound_md5_hash(sk, skb, saddr, daddr, family,
 				    l3index, md5_location);
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index a38408072ea8..edd6748b2cfa 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -33,6 +33,7 @@ struct tcp_ao_key {
 	u8			key[TCP_AO_MAXKEYLEN] __tcp_ao_key_align;
 	unsigned int		tcp_sigpool_id;
 	unsigned int		digest_size;
+	int			l3index;
 	u8			prefixlen;
 	u8			family;
 	u8			keylen;
@@ -200,10 +201,10 @@ int tcp_ao_get_mkts(struct sock *sk, sockptr_t optval, sockptr_t optlen);
 int tcp_ao_get_sock_info(struct sock *sk, sockptr_t optval, sockptr_t optlen);
 enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
 			const struct sk_buff *skb, unsigned short int family,
-			const struct request_sock *req,
+			const struct request_sock *req, int l3index,
 			const struct tcp_ao_hdr *aoh);
 u32 tcp_ao_compute_sne(u32 next_sne, u32 next_seq, u32 seq);
-struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
+struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk, int l3index,
 				    const union tcp_ao_addr *addr,
 				    int family, int sndid, int rcvid);
 int tcp_ao_hash_hdr(unsigned short family, char *ao_hash,
@@ -245,9 +246,6 @@ int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
 			  __be32 disn, bool send);
 int tcp_v6_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
 			   struct request_sock *req);
-struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk,
-				       const struct in6_addr *addr,
-				       int sndid, int rcvid);
 struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
 				    struct sock *addr_sk, int sndid, int rcvid);
 struct tcp_ao_key *tcp_v6_ao_lookup_rsk(const struct sock *sk,
@@ -265,7 +263,7 @@ void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb);
 void tcp_ao_connect_init(struct sock *sk);
 void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
 		      struct tcp_request_sock *treq,
-		      unsigned short int family);
+		      unsigned short int family, int l3index);
 #else /* CONFIG_TCP_AO */
 
 static inline int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
@@ -277,7 +275,7 @@ static inline int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
 
 static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
 				    struct tcp_request_sock *treq,
-				    unsigned short int family)
+				    unsigned short int family, int l3index)
 {
 }
 
@@ -289,13 +287,15 @@ static inline bool tcp_ao_ignore_icmp(const struct sock *sk, int family,
 
 static inline enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
 		const struct sk_buff *skb, unsigned short int family,
-		const struct request_sock *req, const struct tcp_ao_hdr *aoh)
+		const struct request_sock *req, int l3index,
+		const struct tcp_ao_hdr *aoh)
 {
 	return SKB_NOT_DROPPED_YET;
 }
 
 static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
-		const union tcp_ao_addr *addr, int family, int sndid, int rcvid)
+		int l3index, const union tcp_ao_addr *addr,
+		int family, int sndid, int rcvid)
 {
 	return NULL;
 }