net: diag: Support destroying TCP sockets.

This implements SOCK_DESTROY for TCP sockets. It causes all
blocking calls on the socket to fail fast with ECONNABORTED and
causes a protocol close of the socket. It informs the other end
of the connection by sending a RST, i.e., initiating a TCP ABORT
as per RFC 793. ECONNABORTED was chosen for consistency with
FreeBSD.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 0 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 92b3e61b847d..2c0e340518d2 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3080,6 +3080,38 @@ void tcp_done(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(tcp_done);
 
+int tcp_abort(struct sock *sk, int err)
+{
+        if (!sk_fullsock(sk)) {
+                sock_gen_put(sk);
+                return -EOPNOTSUPP;
+        }
+
+        /* Don't race with userspace socket closes such as tcp_close. */
+        lock_sock(sk);
+
+        /* Don't race with BH socket closes such as inet_csk_listen_stop. */
+        local_bh_disable();
+        bh_lock_sock(sk);
+
+        if (!sock_flag(sk, SOCK_DEAD)) {
+                sk->sk_err = err;
+                /* This barrier is coupled with smp_rmb() in tcp_poll() */
+                smp_wmb();
+                sk->sk_error_report(sk);
+                if (tcp_need_reset(sk->sk_state))
+                        tcp_send_active_reset(sk, GFP_ATOMIC);
+                tcp_done(sk);
+        }
+
+        bh_unlock_sock(sk);
+        local_bh_enable();
+        release_sock(sk);
+        sock_put(sk);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(tcp_abort);
+
 extern struct tcp_congestion_ops tcp_reno;
 
 static __initdata unsigned long thash_entries;