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@xxxxxxxxx>
---
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 */
--
2.25.1
