tcp: bind() fix when many ports are bound

Port autoselection done by kernel only works when number of bound
sockets is under a threshold (typically 30000).

When this threshold is over, we must check if there is a conflict before
exiting first loop in inet_csk_get_port()

Change inet_csk_bind_conflict() to forbid two reuse-enabled sockets to
bind on same (address,port) tuple (with a non ANY address)

Same change for inet6_csk_bind_conflict()

Reported-by: Gaspar Chilingarov <gasparch@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 21 insertions, 10 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 8da6429269dd..14825eb09770 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -70,13 +70,17 @@ int inet_csk_bind_conflict(const struct sock *sk,
                     (!sk->sk_bound_dev_if ||
                      !sk2->sk_bound_dev_if ||
                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
+                        const __be32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
+
                         if (!reuse || !sk2->sk_reuse ||
                             sk2->sk_state == TCP_LISTEN) {
-                                const __be32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
                                 if (!sk2_rcv_saddr || !sk_rcv_saddr ||
                                     sk2_rcv_saddr == sk_rcv_saddr)
                                         break;
-                        }
+                        } else if (reuse && sk2->sk_reuse &&
+                                   sk2_rcv_saddr &&
+                                   sk2_rcv_saddr == sk_rcv_saddr)
+                                break;
                 }
         }
         return node != NULL;
@@ -120,9 +124,11 @@ again:
                                                 smallest_size = tb->num_owners;
                                                 smallest_rover = rover;
                                                 if (atomic_read(&hashinfo->bsockets) > (high - low) + 1) {
-                                                        spin_unlock(&head->lock);
-                                                        snum = smallest_rover;
-                                                        goto have_snum;
+                                                        if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
+                                                                spin_unlock(&head->lock);
+                                                                snum = smallest_rover;
+                                                                goto have_snum;
+                                                        }
                                                 }
                                         }
                                         goto next;
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 628db24bcf22..b4b7d40a9c95 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -42,11 +42,16 @@ int inet6_csk_bind_conflict(const struct sock *sk,
                 if (sk != sk2 &&
                     (!sk->sk_bound_dev_if ||
                      !sk2->sk_bound_dev_if ||
-                     sk->sk_bound_dev_if == sk2->sk_bound_dev_if) &&
-                    (!sk->sk_reuse || !sk2->sk_reuse ||
-                     sk2->sk_state == TCP_LISTEN) &&
-                     ipv6_rcv_saddr_equal(sk, sk2))
-                        break;
+                     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
+                        if ((!sk->sk_reuse || !sk2->sk_reuse ||
+                             sk2->sk_state == TCP_LISTEN) &&
+                             ipv6_rcv_saddr_equal(sk, sk2))
+                                break;
+                        else if (sk->sk_reuse && sk2->sk_reuse &&
+                                !ipv6_addr_any(inet6_rcv_saddr(sk2)) &&
+                                ipv6_rcv_saddr_equal(sk, sk2))
+                                break;
+                }
         }
 
         return node != NULL;