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>

1 files changed, 10 insertions, 11 deletions

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,