From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E8A3C35242 for ; Fri, 24 Jan 2020 14:19:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 754DB208C4 for ; Fri, 24 Jan 2020 14:19:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579875558; bh=rT2aUdahCJJgRHdhNyAEat9JFF7mmfvmHnL3jd5FgYI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gCJXRtzwVe/lyNH6EYEnX3mf+ea4r9ePQ9458LNTejf8U498i275+J57yNm4PwhP+ jgw5JKfwOkLZJ7/KPkPZV4ih4/1qR44Q1JosyWhBdWSlVTW34me2h5o0oiCiuzXZ2E EW9p5Z6VgTJcY2gY5XEaXK7Yphb1tzPuFCYyDQzA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391503AbgAXOTR (ORCPT ); Fri, 24 Jan 2020 09:19:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:39384 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391388AbgAXOTN (ORCPT ); Fri, 24 Jan 2020 09:19:13 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 05F32208C4; Fri, 24 Jan 2020 14:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579875552; bh=rT2aUdahCJJgRHdhNyAEat9JFF7mmfvmHnL3jd5FgYI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BL/2K3TsF14oYQkcyjI+s7a8+zrwpTNuH5YHUFqyTS+hHuNOzVtDcm23BZD1HSKrd lNmN6MAdP75l5ZOE9Pgm908yMi7yxanKitRK+O5R/n6MSXLiwgL9+ieJJ54DblB7OS MAyzEVU7tSqafJUIyjWQHJDOmxpn4yPjgfhr+Ykw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Lorenz Bauer , Alexei Starovoitov , Martin KaFai Lau , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 047/107] net: bpf: Don't leak time wait and request sockets Date: Fri, 24 Jan 2020 09:17:17 -0500 Message-Id: <20200124141817.28793-47-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200124141817.28793-1-sashal@kernel.org> References: <20200124141817.28793-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lorenz Bauer [ Upstream commit 2e012c74823629d9db27963c79caa3f5b2010746 ] It's possible to leak time wait and request sockets via the following BPF pseudo code:   sk = bpf_skc_lookup_tcp(...) if (sk) bpf_sk_release(sk) If sk->sk_state is TCP_NEW_SYN_RECV or TCP_TIME_WAIT the refcount taken by bpf_skc_lookup_tcp is not undone by bpf_sk_release. This is because sk_flags is re-used for other data in both kinds of sockets. The check !sock_flag(sk, SOCK_RCU_FREE) therefore returns a bogus result. Check that sk_flags is valid by calling sk_fullsock. Skip checking SOCK_RCU_FREE if we already know that sk is not a full socket. Fixes: edbf8c01de5a ("bpf: add skc_lookup_tcp helper") Fixes: f7355a6c0497 ("bpf: Check sk_fullsock() before returning from bpf_sk_lookup()") Signed-off-by: Lorenz Bauer Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200110132336.26099-1-lmb@cloudflare.com Signed-off-by: Sasha Levin --- net/core/filter.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 2f76461c120d2..3cbf06a466f7d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5305,8 +5305,7 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, if (sk) { sk = sk_to_full_sk(sk); if (!sk_fullsock(sk)) { - if (!sock_flag(sk, SOCK_RCU_FREE)) - sock_gen_put(sk); + sock_gen_put(sk); return NULL; } } @@ -5343,8 +5342,7 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, if (sk) { sk = sk_to_full_sk(sk); if (!sk_fullsock(sk)) { - if (!sock_flag(sk, SOCK_RCU_FREE)) - sock_gen_put(sk); + sock_gen_put(sk); return NULL; } } @@ -5411,7 +5409,8 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = { BPF_CALL_1(bpf_sk_release, struct sock *, sk) { - if (!sock_flag(sk, SOCK_RCU_FREE)) + /* Only full sockets have sk->sk_flags. */ + if (!sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE)) sock_gen_put(sk); return 0; } -- 2.20.1