Merge branch ' bpf fix for unconnect af_unix socket'

John Fastabend says:

====================
Eric reported a syzbot splat from a null ptr deref from recent fix to
resolve a use-after-free with af-unix stream sockets and BPF sockmap
usage.

The issue is I missed is we allow unconnected af_unix STREAM sockets to
be added to the sockmap. Fix this by blocking unconnected sockets.

v2: change sk_is_unix to sk_is_stream_unix (Eric) and remove duplicate
    ASSERTS in selftests the xsocket helper already marks FAIL (Jakub)
====================

Signed-off-by: Martin KaFai Lau <[email protected]>

Author: Martin KaFai Lau

include/net/sock.h

@@ -2799,6 +2799,11 @@ static inline bool sk_is_tcp(const struct sock *sk)
 	return sk->sk_type == SOCK_STREAM && sk->sk_protocol == IPPROTO_TCP;
 }
 
+static inline bool sk_is_stream_unix(const struct sock *sk)
+{
+	return sk->sk_family == AF_UNIX && sk->sk_type == SOCK_STREAM;
+}
+
 /**
  * sk_eat_skb - Release a skb if it is no longer needed
  * @sk: socket to eat this skb from

net/core/sock_map.c

@@ -536,6 +536,8 @@ static bool sock_map_sk_state_allowed(const struct sock *sk)
 {
 	if (sk_is_tcp(sk))
 		return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_LISTEN);
+	if (sk_is_stream_unix(sk))
+		return (1 << sk->sk_state) & TCPF_ESTABLISHED;
 	return true;
 }
 

tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

@@ -524,6 +524,37 @@ static void test_sockmap_skb_verdict_peek(void)
 	test_sockmap_pass_prog__destroy(pass);
 }
 
+static void test_sockmap_unconnected_unix(void)
+{
+	int err, map, stream = 0, dgram = 0, zero = 0;
+	struct test_sockmap_pass_prog *skel;
+
+	skel = test_sockmap_pass_prog__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open_and_load"))
+		return;
+
+	map = bpf_map__fd(skel->maps.sock_map_rx);
+
+	stream = xsocket(AF_UNIX, SOCK_STREAM, 0);
+	if (stream < 0)
+		return;
+
+	dgram = xsocket(AF_UNIX, SOCK_DGRAM, 0);
+	if (dgram < 0) {
+		close(stream);
+		return;
+	}
+
+	err = bpf_map_update_elem(map, &zero, &stream, BPF_ANY);
+	ASSERT_ERR(err, "bpf_map_update_elem(stream)");
+
+	err = bpf_map_update_elem(map, &zero, &dgram, BPF_ANY);
+	ASSERT_OK(err, "bpf_map_update_elem(dgram)");
+
+	close(stream);
+	close(dgram);
+}
+
 void test_sockmap_basic(void)
 {
 	if (test__start_subtest("sockmap create_update_free"))
@@ -566,4 +597,7 @@ void test_sockmap_basic(void)
 		test_sockmap_skb_verdict_fionread(false);
 	if (test__start_subtest("sockmap skb_verdict msg_f_peek"))
 		test_sockmap_skb_verdict_peek();
+
+	if (test__start_subtest("sockmap unconnected af_unix"))
+		test_sockmap_unconnected_unix();
 }