net/tcp: Don't consider TCP_CLOSE in TCP_AO_ESTABLISHED

TCP_CLOSE may or may not have current/rnext keys and should not be
considered "established". The fast-path for TCP_CLOSE is
SKB_DROP_REASON_TCP_CLOSE. This is what tcp_rcv_state_process() does
anyways. Add an early drop path to not spend any time verifying
segment signatures for sockets in TCP_CLOSE state.

Cc: stable@vger.kernel.org # v6.7
Fixes: 0a3a809089eb ("net/tcp: Verify inbound TCP-AO signed segments")
Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://lore.kernel.org/r/20240529-tcp_ao-sk_state-v1-1-d69b5d323c52@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 471e177..5d8e9ed 100644 (file)
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -86,7 +86,8 @@ static inline int tcp_ao_sizeof_key(const struct tcp_ao_key *key)
 struct tcp_ao_info {
        /* List of tcp_ao_key's */
        struct hlist_head       head;
-       /* current_key and rnext_key aren't maintained on listen sockets.
+       /* current_key and rnext_key are maintained on sockets
+        * in TCP_AO_ESTABLISHED states.
         * Their purpose is to cache keys on established connections,
         * saving needless lookups. Never dereference any of them from
         * listen sockets.
@@ -201,9 +202,9 @@ struct tcp6_ao_context {
 };
 
 struct tcp_sigpool;
+/* Established states are fast-path and there always is current_key/rnext_key */
 #define TCP_AO_ESTABLISHED (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | \
-                           TCPF_CLOSE | TCPF_CLOSE_WAIT | \
-                           TCPF_LAST_ACK | TCPF_CLOSING)
+                           TCPF_CLOSE_WAIT | TCPF_LAST_ACK | TCPF_CLOSING)
 
 int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
                        struct tcp_ao_key *key, struct tcphdr *th,

diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 781b67a..37c42b6 100644 (file)
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -933,6 +933,7 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
        struct tcp_ao_key *key;
        __be32 sisn, disn;
        u8 *traffic_key;
+       int state;
        u32 sne = 0;
 
        info = rcu_dereference(tcp_sk(sk)->ao_info);
@@ -948,8 +949,9 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
                disn = 0;
        }
 
+       state = READ_ONCE(sk->sk_state);
        /* Fast-path */
-       if (likely((1 << sk->sk_state) & TCP_AO_ESTABLISHED)) {
+       if (likely((1 << state) & TCP_AO_ESTABLISHED)) {
                enum skb_drop_reason err;
                struct tcp_ao_key *current_key;
 
@@ -988,6 +990,9 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
                return SKB_NOT_DROPPED_YET;
        }
 
+       if (unlikely(state == TCP_CLOSE))
+               return SKB_DROP_REASON_TCP_CLOSE;
+
        /* Lookup key based on peer address and keyid.
         * current_key and rnext_key must not be used on tcp listen
         * sockets as otherwise:
@@ -1001,7 +1006,7 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
        if (th->syn && !th->ack)
                goto verify_hash;
 
-       if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
+       if ((1 << state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
                /* Make the initial syn the likely case here */
                if (unlikely(req)) {
                        sne = tcp_ao_compute_sne(0, tcp_rsk(req)->rcv_isn,
@@ -1018,14 +1023,14 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
                        /* no way to figure out initial sisn/disn - drop */
                        return SKB_DROP_REASON_TCP_FLAGS;
                }
-       } else if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
+       } else if ((1 << state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
                disn = info->lisn;
                if (th->syn || th->rst)
                        sisn = th->seq;
                else
                        sisn = info->risn;
        } else {
-               WARN_ONCE(1, "TCP-AO: Unexpected sk_state %d", sk->sk_state);
+               WARN_ONCE(1, "TCP-AO: Unexpected sk_state %d", state);
                return SKB_DROP_REASON_TCP_AOFAILURE;
        }
 verify_hash: