From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 16E96176FBD; Wed, 3 Jul 2024 11:14:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005254; cv=none; b=TjxgRQeppu9rA2jXiMeOZCWgL/TtnKYZzgJXMgAp2XNm0YnTB0CDmkUCgdzX4PGPkl0FWJSTAwqdtrql9qZ+7DTMTk7Q0eEmNC2tOIJVNVzLYa8acmAPzZ1QTq4hHuoZLaP1HIeuNKbyi4/NUVkp9WVbBJUKdxkY7p4R9S4XLhg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005254; c=relaxed/simple; bh=aXXQt4+VxBCUvIEwEC/qbwiYuJO9ia/tcga8MRJtIRo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GxZlIzIEH3tDccCfVZz2FXG1T5Imbj9e7iHlwxfrN21GvbjD2FcsL/VdewKPM2027DIXmof2hV1t2F91B8b3QojJ5gmBoGj90XvUD0cSwRxAx27gYDQNkEszrvEbKU1et52/URktwYD9JclLR3C0rOmhoOs7Fiv6X+GsikV2eps= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gwJ4PJzp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gwJ4PJzp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90D1AC2BD10; Wed, 3 Jul 2024 11:14:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720005254; bh=aXXQt4+VxBCUvIEwEC/qbwiYuJO9ia/tcga8MRJtIRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gwJ4PJzpRncX5MZ22ltWKI8aHBwNpBs95awjcfICHpjhmP/QTuU6xteNqWJsTSS4P WV6lo3zTdgf8enoRqQExCifF8vA5b4smEKtpR3WrnF1MokMV9hcvzFjG+rqy6rG1cE uplhE9ginjTiddsP1bC7Agk1QlXEj2wNw2Hp2PY0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Paolo Abeni , Sasha Levin Subject: [PATCH 5.15 020/356] af_unix: Set sk->sk_state under unix_state_lock() for truly disconencted peer. Date: Wed, 3 Jul 2024 12:35:56 +0200 Message-ID: <20240703102913.864509376@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102913.093882413@linuxfoundation.org> References: <20240703102913.093882413@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 26bfb8b57063f52b867f9b6c8d1742fcb5bd656c ] When a SOCK_DGRAM socket connect()s to another socket, the both sockets' sk->sk_state are changed to TCP_ESTABLISHED so that we can register them to BPF SOCKMAP. When the socket disconnects from the peer by connect(AF_UNSPEC), the state is set back to TCP_CLOSE. Then, the peer's state is also set to TCP_CLOSE, but the update is done locklessly and unconditionally. Let's say socket A connect()ed to B, B connect()ed to C, and A disconnects from B. After the first two connect()s, all three sockets' sk->sk_state are TCP_ESTABLISHED: $ ss -xa Netid State Recv-Q Send-Q Local Address:Port Peer Address:PortProcess u_dgr ESTAB 0 0 @A 641 * 642 u_dgr ESTAB 0 0 @B 642 * 643 u_dgr ESTAB 0 0 @C 643 * 0 And after the disconnect, B's state is TCP_CLOSE even though it's still connected to C and C's state is TCP_ESTABLISHED. $ ss -xa Netid State Recv-Q Send-Q Local Address:Port Peer Address:PortProcess u_dgr UNCONN 0 0 @A 641 * 0 u_dgr UNCONN 0 0 @B 642 * 643 u_dgr ESTAB 0 0 @C 643 * 0 In this case, we cannot register B to SOCKMAP. So, when a socket disconnects from the peer, we should not set TCP_CLOSE to the peer if the peer is connected to yet another socket, and this must be done under unix_state_lock(). Note that we use WRITE_ONCE() for sk->sk_state as there are many lockless readers. These data-races will be fixed in the following patches. Fixes: 83301b5367a9 ("af_unix: Set TCP_ESTABLISHED for datagram sockets too") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/unix/af_unix.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 80f91b5ab4012..914e40697f00a 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -495,7 +495,6 @@ static void unix_dgram_disconnected(struct sock *sk, struct sock *other) sk_error_report(other); } } - other->sk_state = TCP_CLOSE; } static void unix_sock_destructor(struct sock *sk) @@ -1277,8 +1276,15 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr, unix_state_double_unlock(sk, other); - if (other != old_peer) + if (other != old_peer) { unix_dgram_disconnected(sk, old_peer); + + unix_state_lock(old_peer); + if (!unix_peer(old_peer)) + WRITE_ONCE(old_peer->sk_state, TCP_CLOSE); + unix_state_unlock(old_peer); + } + sock_put(old_peer); } else { unix_peer(sk) = other; -- 2.43.0