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: 314001f0bf ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
b94038d841