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: 2100c8d2d9db ("net-tcp: Fast Open base")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 8baef2f..252c8bc 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -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) {

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b1b1bcb..2faaaaf 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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

diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index fdbcf2a..0acdb54 100644 (file)
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -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;