According to the RFC we should use the key that the peer suggests via rnextkeyid.
This is currently done by storing recv_rnextkeyid in tcp_authopt_info but this does not work for the SYNACK case because the tcp_request_sock does not hold an info pointer for reasons of memory usage.
Handle this by storing recv_rnextkeyid inside tcp_request_sock. This doesn't increase the memory usage because there are unused bytes at the end.
Signed-off-by: Leonard Crestez cdleonard@gmail.com --- include/linux/tcp.h | 6 ++++++ net/ipv4/tcp_authopt.c | 14 +++++++++++--- net/ipv4/tcp_input.c | 12 ++++++++++++ 3 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 551942883f06..6a4ff0ed55c6 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -125,10 +125,13 @@ struct tcp_options_received { u8 saw_unknown:1, /* Received unknown option */ unused:7; u8 num_sacks; /* Number of SACK blocks */ u16 user_mss; /* mss requested by user in ioctl */ u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ +#if IS_ENABLED(CONFIG_TCP_AUTHOPT) + u8 rnextkeyid; +#endif };
static inline void tcp_clear_options(struct tcp_options_received *rx_opt) { rx_opt->tstamp_ok = rx_opt->sack_ok = 0; @@ -163,10 +166,13 @@ struct tcp_request_sock { u32 rcv_nxt; /* the ack # by SYNACK. For * FastOpen it's the seq# * after data-in-SYN. */ u8 syn_tos; +#if IS_ENABLED(CONFIG_TCP_AUTHOPT) + u8 recv_rnextkeyid; +#endif };
static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) { return (struct tcp_request_sock *)req; diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c index 2a1ddae69b27..a141439d9ebe 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -547,21 +547,29 @@ struct tcp_authopt_key_info *__tcp_authopt_select_key(const struct sock *sk, struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk); bool anykey = false; int pref_send_id;
/* Listen sockets don't refer to any specific connection so we don't try - * to keep using the same key and ignore any received keyids. + * to keep using the same key. + * The rnextkeyid is stored in tcp_request_sock */ if (sk->sk_state == TCP_LISTEN) { + struct tcp_request_sock *rsk; + + if (WARN_ONCE(addr_sk->sk_state != TCP_NEW_SYN_RECV, "bad socket state")) + return NULL; + rsk = tcp_rsk((struct request_sock *)addr_sk); + /* Forcing a specific send_keyid on a listen socket forces it for + * all clients so is unlikely to be useful. + */ if (info->flags & TCP_AUTHOPT_FLAG_LOCK_KEYID) pref_send_id = info->user_pref_send_keyid; else - pref_send_id = -1; + pref_send_id = rsk->recv_rnextkeyid; key = tcp_authopt_lookup_send(net, addr_sk, pref_send_id, rnextkeyid, &anykey); if (!key && anykey) return ERR_PTR(-ENOKEY); - return key; }
/* Try to keep the same sending key unless user or peer requires a different key * User request (via TCP_AUTHOPT_FLAG_LOCK_KEYID) always overrides peer request. diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 4da39c32b934..6f477b110896 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4108,10 +4108,18 @@ void tcp_parse_options(const struct net *net, /* * The MD5 Hash has already been * checked (see tcp_v{4,6}_do_rcv()). */ break; +#endif +#ifdef CONFIG_TCP_AUTHOPT + case TCPOPT_AUTHOPT: + /* Hash has already been checked. + * We parse rnextkeyid here so we can match it on synack + */ + opt_rx->rnextkeyid = ptr[1]; + break; #endif case TCPOPT_FASTOPEN: tcp_parse_fastopen_option( opsize - TCPOLEN_FASTOPEN_BASE, ptr, th->syn, foc, false); @@ -6964,10 +6972,14 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, tcp_clear_options(&tmp_opt);
if (IS_ENABLED(CONFIG_SMC) && want_cookie) tmp_opt.smc_ok = 0;
+#if IS_ENABLED(CONFIG_TCP_AUTHOPT) + tcp_rsk(req)->recv_rnextkeyid = tmp_opt.rnextkeyid; +#endif + tmp_opt.tstamp_ok = tmp_opt.saw_tstamp; tcp_openreq_init(req, &tmp_opt, skb, sk); inet_rsk(req)->no_srccheck = inet_sk(sk)->transparent;
/* Note: tcp_v6_init_req() might override ir_iif for link locals */