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 | 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 497604176119..0c346c2c2145 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -95,10 +95,13 @@ 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;
@@ -133,10 +136,13 @@ 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 5ea93eb495f1..4b316488c805 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>
@@ -424,21 +426,33 @@ 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 91f1b04c1933..667da79df4ae 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4094,10 +4094,18 @@ 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);
@@ -6891,10 +6899,14 @@ 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
