6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
[ Upstream commit b94038d841a91d0e3f59cfe4d073e210910366ee ]
After consuming OOB data, recv() reading the preceding data must break at
the OOB skb regardless of MSG_PEEK.
Currently, MSG_PEEK does not stop recv() for AF_UNIX, and the behaviour is
not compliant with TCP.
>>> from socket import *
>>> c1, c2 = socketpair(AF_UNIX)
>>> c1.send(b'hello', MSG_OOB)
5
>>> c1.send(b'world')
5
>>> c2.recv(1, MSG_OOB)
b'o'
>>> c2.recv(9, MSG_PEEK) # This should return b'hell'
b'hellworld' # even with enough buffer.
Let's fix it by returning NULL for consumed skb and unlinking it only if
MSG_PEEK is not specified.
This patch also adds test cases that add recv(MSG_PEEK) before each recv().
Without fix:
# RUN msg_oob.peek.oob_ahead_break ...
# msg_oob.c:134:oob_ahead_break:AF_UNIX :hellworld
# msg_oob.c:135:oob_ahead_break:Expected:hell
# msg_oob.c:137:oob_ahead_break:Expected ret[0] (9) == expected_len (4)
# oob_ahead_break: Test terminated by assertion
# FAIL msg_oob.peek.oob_ahead_break
not ok 13 msg_oob.peek.oob_ahead_break
With fix:
# RUN msg_oob.peek.oob_ahead_break ...
# OK msg_oob.peek.oob_ahead_break
ok 13 msg_oob.peek.oob_ahead_break
Fixes: 314001f0bf92 ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/unix/af_unix.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 68a58bc07cf23..d687670e84990 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2660,9 +2660,12 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
{
struct unix_sock *u = unix_sk(sk);
- if (!unix_skb_len(skb) && !(flags & MSG_PEEK)) {
- skb_unlink(skb, &sk->sk_receive_queue);
- consume_skb(skb);
+ if (!unix_skb_len(skb)) {
+ if (!(flags & MSG_PEEK)) {
+ skb_unlink(skb, &sk->sk_receive_queue);
+ consume_skb(skb);
+ }
+
skb = NULL;
} else {
struct sk_buff *unlinked_skb = NULL;
--
2.43.0
