Merge branch 'net: bpf: handle return value of post_bind{4,6} and add selftests for it'

Menglong Dong says:

====================

From: Menglong Dong <imagedong@tencent.com>

The return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() in
__inet_bind() is not handled properly. While the return value
is non-zero, it will set inet_saddr and inet_rcv_saddr to 0 and
exit:

        err = BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk);
        if (err) {
                inet->inet_saddr = inet->inet_rcv_saddr = 0;
                goto out_release_sock;
        }

Let's take UDP for example and see what will happen. For UDP
socket, it will be added to 'udp_prot.h.udp_table->hash' and
'udp_prot.h.udp_table->hash2' after the sk->sk_prot->get_port()
called success. If 'inet->inet_rcv_saddr' is specified here,
then 'sk' will be in the 'hslot2' of 'hash2' that it don't belong
to (because inet_saddr is changed to 0), and UDP packet received
will not be passed to this sock. If 'inet->inet_rcv_saddr' is not
specified here, the sock will work fine, as it can receive packet
properly, which is wired, as the 'bind()' is already failed.

To undo the get_port() operation, introduce the 'put_port' field
for 'struct proto'. For TCP proto, it is inet_put_port(); For UDP
proto, it is udp_lib_unhash(); For icmp proto, it is
ping_unhash().

Therefore, after sys_bind() fail caused by
BPF_CGROUP_RUN_PROG_INET4_POST_BIND(), it will be unbinded, which
means that it can try to be binded to another port.

The second patch use C99 initializers in test_sock.c

The third patch is the selftests for this modification.

Changes since v4:
- use C99 initializers in test_sock.c before adding the test case

Changes since v3:
- add the third patch which use C99 initializers in test_sock.c

Changes since v2:
- NULL check for sk->sk_prot->put_port

Changes since v1:
- introduce 'put_port' field for 'struct proto'
- add selftests for it
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

4 files changed, 5 insertions, 0 deletions

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index d1636425654e..8fe7900f1949 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -413,6 +413,8 @@ static int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
 			if (err) {
 				sk->sk_ipv6only = saved_ipv6only;
 				inet_reset_saddr(sk);
+				if (sk->sk_prot->put_port)
+					sk->sk_prot->put_port(sk);
 				goto out;
 			}
 		}
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index 6ac88fe24a8e..9256f6ba87ef 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -177,6 +177,7 @@ struct proto pingv6_prot = {
 	.hash =		ping_hash,
 	.unhash =	ping_unhash,
 	.get_port =	ping_get_port,
+	.put_port =	ping_unhash,
 	.obj_size =	sizeof(struct raw6_sock),
 };
 EXPORT_SYMBOL_GPL(pingv6_prot);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 1ac243d18c2b..075ee8a2df3b 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2181,6 +2181,7 @@ struct proto tcpv6_prot = {
 	.hash			= inet6_hash,
 	.unhash			= inet_unhash,
 	.get_port		= inet_csk_get_port,
+	.put_port		= inet_put_port,
 #ifdef CONFIG_BPF_SYSCALL
 	.psock_update_sk_prot	= tcp_bpf_update_proto,
 #endif
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 1accc06abc54..90718a924ca8 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1732,6 +1732,7 @@ struct proto udpv6_prot = {
 	.unhash			= udp_lib_unhash,
 	.rehash			= udp_v6_rehash,
 	.get_port		= udp_v6_get_port,
+	.put_port		= udp_lib_unhash,
 #ifdef CONFIG_BPF_SYSCALL
 	.psock_update_sk_prot	= udp_bpf_update_proto,
 #endif