From b94038d841a91d0e3f59cfe4d073e210910366ee Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Mon, 24 Jun 2024 18:36:37 -0700 Subject: [PATCH] af_unix: Stop recv(MSG_PEEK) at consumed OOB skb. 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 Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 9 ++++--- tools/testing/selftests/net/af_unix/msg_oob.c | 25 +++++++++++++++++-- 2 files changed, 29 insertions(+), 5 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 5e695a9a609c..2eaecf9d78a4 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2613,9 +2613,12 @@ 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; diff --git a/tools/testing/selftests/net/af_unix/msg_oob.c b/tools/testing/selftests/net/af_unix/msg_oob.c index d427d39d0806..de8d1fcde883 100644 --- a/tools/testing/selftests/net/af_unix/msg_oob.c +++ b/tools/testing/selftests/net/af_unix/msg_oob.c @@ -21,6 +21,21 @@ FIXTURE(msg_oob) */ }; +FIXTURE_VARIANT(msg_oob) +{ + bool peek; +}; + +FIXTURE_VARIANT_ADD(msg_oob, no_peek) +{ + .peek = false, +}; + +FIXTURE_VARIANT_ADD(msg_oob, peek) +{ + .peek = true +}; + static void create_unix_socketpair(struct __test_metadata *_metadata, FIXTURE_DATA(msg_oob) *self) { @@ -156,8 +171,14 @@ static void __recvpair(struct __test_metadata *_metadata, __sendpair(_metadata, self, buf, len, flags) #define recvpair(expected_buf, expected_len, buf_len, flags) \ - __recvpair(_metadata, self, \ - expected_buf, expected_len, buf_len, flags) + do { \ + if (variant->peek) \ + __recvpair(_metadata, self, \ + expected_buf, expected_len, \ + buf_len, (flags) | MSG_PEEK); \ + __recvpair(_metadata, self, \ + expected_buf, expected_len, buf_len, flags); \ + } while (0) TEST_F(msg_oob, non_oob) {