From: Dmitry Safonov 0x7f454c46@gmail.com

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 --- include/net/tcp_ao.h | 7 ++++--- net/ipv4/tcp_ao.c | 13 +++++++++---- 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index 471e177362b4..5d8e9ed2c005 100644 --- 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 781b67a52571..37c42b63ff99 100644 --- 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:

--- base-commit: e0cce98fe279b64f4a7d81b7f5c3a23d80b92fbc change-id: 20240529-tcp_ao-sk_state-4eb21b045001

Best regards,