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 | 26 ++++++++++++++++++++------ net/ipv4/tcp_input.c | 12 ++++++++++++ 3 files changed, 38 insertions(+), 6 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 00d749aa1025..3596fc1fb770 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -1,7 +1,9 @@ // SPDX-License-Identifier: GPL-2.0-or-later
+#include "linux/tcp.h" +#include "net/tcp_states.h" #include <net/tcp_authopt.h> #include <net/ip.h> #include <net/ipv6.h> #include <net/tcp.h> #include <linux/kref.h> @@ -435,21 +437,33 @@ struct tcp_authopt_key_info *__tcp_authopt_select_key(const struct sock *sk, { struct tcp_authopt_key_info *key, *new_key = NULL; struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk);
/* 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) { - int send_keyid = -1; - + int send_id = -1; + 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) - send_keyid = info->send_keyid; - key = tcp_authopt_lookup_send(net, addr_sk, send_keyid); + send_id = info->send_keyid; + else + send_id = rsk->recv_rnextkeyid; + key = tcp_authopt_lookup_send(net, addr_sk, send_id); + /* If no key found with specific send_id try anything else. */ + if (!key) + key = tcp_authopt_lookup_send(net, addr_sk, -1); if (key) *rnextkeyid = key->recv_id; - return key; }
if (locked) { sock_owned_by_me(sk); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index c09d42614b2b..6f2af45f4271 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4105,10 +4105,18 @@ 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); @@ -6958,10 +6966,14 @@ 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 */