Commit 5a542133 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

tcp: Fix data-races around sysctl_tcp_fastopen. 



While reading sysctl_tcp_fastopen, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 2100c8d2 ("net-tcp: Fast Open base")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 79539f34

net/ipv4/af_inet.c

+1 −1
Original line number Diff line number Diff line
@@ -217,7 +217,7 @@ int inet_listen(struct socket *sock, int backlog) 
		 * because the socket was in TCP_LISTEN state previously but

		 * was shutdown() rather than close().

		 */

		tcp_fastopen = sock_net(sk)->ipv4.sysctl_tcp_fastopen;

		tcp_fastopen = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen);

		if ((tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) &&

		    (tcp_fastopen & TFO_SERVER_ENABLE) &&

		    !inet_csk(sk)->icsk_accept_queue.fastopenq.max_qlen) {

net/ipv4/tcp.c

+4 −2
Original line number Diff line number Diff line
@@ -1150,7 +1150,8 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, 
	struct sockaddr *uaddr = msg->msg_name;

	int err, flags;



	if (!(sock_net(sk)->ipv4.sysctl_tcp_fastopen & TFO_CLIENT_ENABLE) ||

	if (!(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen) &

	      TFO_CLIENT_ENABLE) ||

	    (uaddr && msg->msg_namelen >= sizeof(uaddr->sa_family) &&

	     uaddr->sa_family == AF_UNSPEC))

		return -EOPNOTSUPP;
@@ -3617,7 +3618,8 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname, 
	case TCP_FASTOPEN_CONNECT:

		if (val > 1 || val < 0) {

			err = -EINVAL;

		} else if (net->ipv4.sysctl_tcp_fastopen & TFO_CLIENT_ENABLE) {

		} else if (READ_ONCE(net->ipv4.sysctl_tcp_fastopen) &

			   TFO_CLIENT_ENABLE) {

			if (sk->sk_state == TCP_CLOSE)

				tp->fastopen_connect = val;

			else

net/ipv4/tcp_fastopen.c

+2 −2
Original line number Diff line number Diff line
@@ -332,7 +332,7 @@ static bool tcp_fastopen_no_cookie(const struct sock *sk, 
				   const struct dst_entry *dst,

				   int flag)

{

	return (sock_net(sk)->ipv4.sysctl_tcp_fastopen & flag) ||

	return (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen) & flag) ||

	       tcp_sk(sk)->fastopen_no_cookie ||

	       (dst && dst_metric(dst, RTAX_FASTOPEN_NO_COOKIE));

}
@@ -347,7 +347,7 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 
			      const struct dst_entry *dst)

{

	bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1;

	int tcp_fastopen = sock_net(sk)->ipv4.sysctl_tcp_fastopen;

	int tcp_fastopen = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen);

	struct tcp_fastopen_cookie valid_foc = { .len = -1 };

	struct sock *child;

	int ret = 0;