From patchwork Sun Mar 16 22:45:08 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michal Luczaj X-Patchwork-Id: 14018542 Received: from mailtransmit04.runbox.com (mailtransmit04.runbox.com [185.226.149.37]) (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 8E77B1A0BDB; Sun, 16 Mar 2025 22:46:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.226.149.37 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742165176; cv=none; b=TGrgRM2gJK5GtdY2ms4OnlTq09zIUdHRCySD0iSgCXKg24KlcWu8owcl62PJDJ0FltxZeCjoDT8kE1OURO5NqAbuMp8RP0Bx6OUzVTKZZlg11cVitJ8wlvhMTP22tHdxUcu8t6Q45k4vLlxrpEwrAgbBLpLvuarFdaRYnKsYrF4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742165176; c=relaxed/simple; bh=WKSI5tQo2ZCmquUaEjyal9KCtNxILWDmnnMtd21oT78=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=pORzolT+N4USd4RKWv+3gUIXc05BA6L/8VXKdkpilY+43M19srsOISfcxPWHmYIWc+B8/GP8iCI2W+wL8qBhTmDc92f7ECsEWH4G3kgKzcFTX9UiYG9Jq4PreVv5inkwHor0JzCdTzeRQHPEJ+nfhtRAnMJLtqLC5KMXrm7PGZY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rbox.co; spf=pass smtp.mailfrom=rbox.co; dkim=pass (2048-bit key) header.d=rbox.co header.i=@rbox.co header.b=R2VSz5G1; arc=none smtp.client-ip=185.226.149.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rbox.co Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rbox.co Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rbox.co header.i=@rbox.co header.b="R2VSz5G1" Received: from mailtransmit02.runbox ([10.9.9.162] helo=aibo.runbox.com) by mailtransmit04.runbox.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1ttwkB-00Csg5-P0; Sun, 16 Mar 2025 23:46:07 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=rbox.co; s=selector1; h=Cc:To:In-Reply-To:References:Message-Id: Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date:From; bh=Qx6Q42lUm6Tq+A/H1tasLuFXsBAYaSnDK2lri+KURPw=; b=R2VSz5G1geS1IlY9yhGry/JtS+ jcIBvCOu0tq8IgLofQRHs/DLjNAneUf/Q/K9l0lBEpKvniVT8OPxLbZZb8xQieGrQvVohG+4J1jnU 5qkvnKZ80va+ERUtZjt8tdCtnhsrsC4kMQWPC8NIjnzjhZpYZe96gRUbSViEbjrD0gqZrI+1ydSsm SgyuS711t1C0s7vL0qifdIzNAE1ihEQi0s111p3j0oiartg7K/VLMbWYsBpco+bFArKFyEwGM0R7f C9kPv8eYHXfVLKnHcEfU8ehbKO3X61bShgw9CWx+zOg0P7dlVYQtTyWzWoTpNlZCK1w0w/MrFT+lh HkI6NlFA==; Received: from [10.9.9.74] (helo=submission03.runbox) by mailtransmit02.runbox with esmtp (Exim 4.86_2) (envelope-from ) id 1ttwkB-0007hM-Ap; Sun, 16 Mar 2025 23:46:07 +0100 Received: by submission03.runbox with esmtpsa [Authenticated ID (604044)] (TLS1.2:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.93) id 1ttwjr-00AYw2-L6; Sun, 16 Mar 2025 23:45:47 +0100 From: Michal Luczaj Date: Sun, 16 Mar 2025 23:45:08 +0100 Subject: [PATCH net v3 3/3] vsock/bpf: Fix bpf recvmsg() racing transport reassignment Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250316-vsock-trans-signal-race-v3-3-17a6862277c9@rbox.co> References: <20250316-vsock-trans-signal-race-v3-0-17a6862277c9@rbox.co> In-Reply-To: <20250316-vsock-trans-signal-race-v3-0-17a6862277c9@rbox.co> To: Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , "Michael S. Tsirkin" , Bobby Eshleman , Andrii Nakryiko , Eduard Zingerman , Mykola Lysenko , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Michal Luczaj X-Mailer: b4 0.14.2 Signal delivery during connect() may lead to a disconnect of an already established socket. That involves removing socket from any sockmap and resetting state to SS_UNCONNECTED. While it correctly restores socket's proto, a call to vsock_bpf_recvmsg() might have been already under way in another thread. If the connect()ing thread reassigns the vsock transport to NULL, the recvmsg()ing thread may trigger a WARN_ON_ONCE. connect / state = SS_CONNECTED / sock_map_update_elem vsock_bpf_recvmsg psock = sk_psock_get() lock sk if signal_pending unhash sock_map_remove_links state = SS_UNCONNECTED release sk connect transport = NULL lock sk WARN_ON_ONCE(!vsk->transport) Protect recvmsg() from racing against transport reassignment. Enforce the sockmap invariant that psock implies transport: lock socket before getting psock. WARNING: CPU: 9 PID: 1222 at net/vmw_vsock/vsock_bpf.c:92 vsock_bpf_recvmsg+0xb55/0xe00 CPU: 9 UID: 0 PID: 1222 Comm: a.out Not tainted 6.14.0-rc5+ RIP: 0010:vsock_bpf_recvmsg+0xb55/0xe00 sock_recvmsg+0x1b2/0x220 __sys_recvfrom+0x190/0x270 __x64_sys_recvfrom+0xdc/0x1b0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Fixes: 634f1a7110b4 ("vsock: support sockmap") Signed-off-by: Michal Luczaj --- net/vmw_vsock/vsock_bpf.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/net/vmw_vsock/vsock_bpf.c b/net/vmw_vsock/vsock_bpf.c index c68fdaf09046b68254dac3ea70ffbe73dfa45cef..5138195d91fb258d4bc09b48e80e13651d62863a 100644 --- a/net/vmw_vsock/vsock_bpf.c +++ b/net/vmw_vsock/vsock_bpf.c @@ -73,28 +73,35 @@ static int __vsock_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int return err; } -static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, - size_t len, int flags, int *addr_len) +static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, + int flags, int *addr_len) { struct sk_psock *psock; struct vsock_sock *vsk; int copied; + /* Since signal delivery during connect() may reset the state of socket + * that's already in a sockmap, take the lock before checking on psock. + * This serializes a possible transport reassignment, protecting this + * function from running with NULL transport. + */ + lock_sock(sk); + psock = sk_psock_get(sk); - if (unlikely(!psock)) + if (unlikely(!psock)) { + release_sock(sk); return __vsock_recvmsg(sk, msg, len, flags); + } - lock_sock(sk); vsk = vsock_sk(sk); - if (WARN_ON_ONCE(!vsk->transport)) { copied = -ENODEV; goto out; } if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) { - release_sock(sk); sk_psock_put(sk, psock); + release_sock(sk); return __vsock_recvmsg(sk, msg, len, flags); } @@ -108,8 +115,8 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, } if (sk_psock_queue_empty(psock)) { - release_sock(sk); sk_psock_put(sk, psock); + release_sock(sk); return __vsock_recvmsg(sk, msg, len, flags); } @@ -117,8 +124,8 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, } out: - release_sock(sk); sk_psock_put(sk, psock); + release_sock(sk); return copied; }