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>

3 files changed, 25 insertions, 16 deletions

diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index ad7a8caa7b2a..500f6ed3b8cf 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -140,6 +140,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 	struct dst_entry *dst;
 	__u8 rcv_wscale;
 	u32 tsoff = 0;
+	int l3index;
 
 	if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_syncookies) ||
 	    !th->ack || th->rst)
@@ -214,7 +215,9 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 	treq->snt_isn = cookie;
 	treq->ts_off = 0;
 	treq->txhash = net_tx_rndhash();
-	tcp_ao_syncookie(sk, skb, treq, AF_INET6);
+
+	l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);
+	tcp_ao_syncookie(sk, skb, treq, AF_INET6, l3index);
 
 	if (IS_ENABLED(CONFIG_SMC))
 		ireq->smc_ok = 0;
diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c
index 8b04611c9078..3c09ac26206e 100644
--- a/net/ipv6/tcp_ao.c
+++ b/net/ipv6/tcp_ao.c
@@ -87,30 +87,29 @@ int tcp_v6_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
 			htonl(tcp_rsk(req)->rcv_isn));
 }
 
-struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk,
-				       const struct in6_addr *addr,
-				       int sndid, int rcvid)
-{
-	return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)addr, AF_INET6,
-				sndid, rcvid);
-}
-
 struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
 				    struct sock *addr_sk,
 				    int sndid, int rcvid)
 {
+	int l3index = l3mdev_master_ifindex_by_index(sock_net(sk),
+						     addr_sk->sk_bound_dev_if);
 	struct in6_addr *addr = &addr_sk->sk_v6_daddr;
 
-	return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid);
+	return tcp_ao_do_lookup(sk, l3index, (union tcp_ao_addr *)addr,
+				AF_INET6, sndid, rcvid);
 }
 
 struct tcp_ao_key *tcp_v6_ao_lookup_rsk(const struct sock *sk,
 					struct request_sock *req,
 					int sndid, int rcvid)
 {
-	struct in6_addr *addr = &inet_rsk(req)->ir_v6_rmt_addr;
+	struct inet_request_sock *ireq = inet_rsk(req);
+	struct in6_addr *addr = &ireq->ir_v6_rmt_addr;
+	int l3index;
 
-	return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid);
+	l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);
+	return tcp_ao_do_lookup(sk, l3index, (union tcp_ao_addr *)addr,
+				AF_INET6, sndid, rcvid);
 }
 
 int tcp_v6_ao_hash_pseudoheader(struct tcp_sigpool *hp,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index b5936294dba2..937a02c2e534 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -610,6 +610,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 	union tcp_ao_addr *addr;
 	int l3index = 0;
 	u8 prefixlen;
+	bool l3flag;
 	u8 flags;
 
 	if (optlen < sizeof(cmd))
@@ -622,6 +623,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 		return -EINVAL;
 
 	flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
+	l3flag = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
 
 	if (optname == TCP_MD5SIG_EXT &&
 	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
@@ -668,7 +670,8 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 		/* Don't allow keys for peers that have a matching TCP-AO key.
 		 * See the comment in tcp_ao_add_cmd()
 		 */
-		if (tcp_ao_required(sk, addr, AF_INET, false))
+		if (tcp_ao_required(sk, addr, AF_INET,
+				    l3flag ? l3index : -1, false))
 			return -EKEYREJECTED;
 		return tcp_md5_do_add(sk, addr,
 				      AF_INET, prefixlen, l3index, flags,
@@ -680,7 +683,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 	/* Don't allow keys for peers that have a matching TCP-AO key.
 	 * See the comment in tcp_ao_add_cmd()
 	 */
-	if (tcp_ao_required(sk, addr, AF_INET6, false))
+	if (tcp_ao_required(sk, addr, AF_INET6, l3flag ? l3index : -1, false))
 		return -EKEYREJECTED;
 
 	return tcp_md5_do_add(sk, addr, AF_INET6, prefixlen, l3index, flags,
@@ -1220,10 +1223,14 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 			return;
 		if (!aoh)
 			return;
-		key.ao_key = tcp_v6_ao_do_lookup(sk, addr, aoh->rnext_keyid, -1);
+		key.ao_key = tcp_ao_do_lookup(sk, l3index,
+					      (union tcp_ao_addr *)addr,
+					      AF_INET6, aoh->rnext_keyid, -1);
 		if (unlikely(!key.ao_key)) {
 			/* Send ACK with any matching MKT for the peer */
-			key.ao_key = tcp_v6_ao_do_lookup(sk, addr, -1, -1);
+			key.ao_key = tcp_ao_do_lookup(sk, l3index,
+						      (union tcp_ao_addr *)addr,
+						      AF_INET6, -1, -1);
 			/* Matching key disappeared (user removed the key?)
 			 * let the handshake timeout.
 			 */