From nobody Fri May 17 10:44:27 2024 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 62CB53B2A6 for ; Fri, 29 Mar 2024 18:51:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711738266; cv=none; b=kM7DSJ2B3M9+ai9N6P9C4ifaCbTHTg0FMUWKcigsr4Gf13ZH6PtuWK1jiFujW+3uWULpmd1G8TGjVh/cqkUyanKXbTEco/T4Ct40pwHAZmw88+2bgxvMJfMtUT76P2Ny+hd5f8f6wK8Dw9lfJaGHgrCWK7FInc8LlteP0VIZ5JI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711738266; c=relaxed/simple; bh=tcqWZa7vAgYqVfEKtTYMRoETyY0uk7xPdEJmlLmv2hU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=WrjcArYBZHLPx+kJ6TGoqnimZ9gZWQ7NePdgg5abgiufJO5cVnmRILDZLC5RLm+WweR2d7D5XL8/kr/5WJ88gQJi2ab3P2ovv3OOl8IF5NYbuhYZXZ1wF382vN8Mhj/Z51ZBKBg3S4uWZxyVvud9tH0O/y7KzsTIc007vlV8kvM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ghM3w2lS; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ghM3w2lS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1711738262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=W8dzUgdlpUNa2rUoysoERPwae2lgTaSmib26erqINq0=; b=ghM3w2lS81wu6/kpZCwXP9t7E3npAAH+xxa19N7SXEKK/Pm3S3xegMM+a46hWo+MjgAlFj FrQN8LS73bCN4abqd5NWiOcowsQ0osBj601Svl/KaQMrmWGWJ3yCdd1o5+7skSIX9PBSAQ Xio8IXTECXZsXkjBLA8y4ZBGc3XPscI= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-210-ZTgBXhmTOfGzXh-REwQkxw-1; Fri, 29 Mar 2024 14:50:58 -0400 X-MC-Unique: ZTgBXhmTOfGzXh-REwQkxw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9D3992804803; Fri, 29 Mar 2024 18:50:57 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.224.119]) by smtp.corp.redhat.com (Postfix) with ESMTP id C9A48492BC8; Fri, 29 Mar 2024 18:50:55 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: Matthieu Baerts , Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , mptcp@lists.linux.dev, bpf@vger.kernel.org Subject: [PATCH net] mptcp: prevent BPF accessing lowat from a subflow socket. Date: Fri, 29 Mar 2024 19:50:36 +0100 Message-ID: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Content-Type: text/plain; charset="utf-8" Alexei reported the following splat: WARNING: CPU: 32 PID: 3276 at net/mptcp/subflow.c:1430 subflow_data_ready+= 0x147/0x1c0 Modules linked in: dummy bpf_testmod(O) [last unloaded: bpf_test_no_cfi(O)] CPU: 32 PID: 3276 Comm: test_progs Tainted: GO 6.8.0-12873-g2c43c33b= fd23 Call Trace: mptcp_set_rcvlowat+0x79/0x1d0 sk_setsockopt+0x6c0/0x1540 __bpf_setsockopt+0x6f/0x90 bpf_sock_ops_setsockopt+0x3c/0x90 bpf_prog_509ce5db2c7f9981_bpf_test_sockopt_int+0xb4/0x11b bpf_prog_dce07e362d941d2b_bpf_test_socket_sockopt+0x12b/0x132 bpf_prog_348c9b5faaf10092_skops_sockopt+0x954/0xe86 __cgroup_bpf_run_filter_sock_ops+0xbc/0x250 tcp_connect+0x879/0x1160 tcp_v6_connect+0x50c/0x870 mptcp_connect+0x129/0x280 __inet_stream_connect+0xce/0x370 inet_stream_connect+0x36/0x50 bpf_trampoline_6442491565+0x49/0xef inet_stream_connect+0x5/0x50 __sys_connect+0x63/0x90 __x64_sys_connect+0x14/0x20 The root cause of the issue is that bpf allows accessing mptcp-level proto_ops from a tcp subflow scope. Fix the issue detecting the problematic call and preventing any action. Reported-by: Alexei Starovoitov Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/482 Fixes: 5684ab1a0eff ("mptcp: give rcvlowat some love") Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Reviewed-by: Matthieu Baerts (NGI0) --- net/mptcp/sockopt.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index dcd1c76d2a3b..73fdf423de44 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -1493,6 +1493,10 @@ int mptcp_set_rcvlowat(struct sock *sk, int val) struct mptcp_subflow_context *subflow; int space, cap; =20 + /* bpf can land here with a wrong sk type */ + if (sk->sk_protocol =3D=3D IPPROTO_TCP) + return -EINVAL; + if (sk->sk_userlocks & SOCK_RCVBUF_LOCK) cap =3D sk->sk_rcvbuf >> 1; else --=20 2.43.2