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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 3A5EFC33CA2 for ; Fri, 10 Jan 2020 13:25:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C45B20721 for ; Fri, 10 Jan 2020 13:25:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="Vh0GCGNe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727358AbgAJNZv (ORCPT ); Fri, 10 Jan 2020 08:25:51 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:36985 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727484AbgAJNZv (ORCPT ); Fri, 10 Jan 2020 08:25:51 -0500 Received: by mail-wm1-f68.google.com with SMTP id f129so1974166wmf.2 for ; Fri, 10 Jan 2020 05:25:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=pPkkayMqoY404hwMIWti3s+tl9smeoH8DKQs1LSa8V4=; b=Vh0GCGNeW4bRhhYlzpky0Y1SiaDf4HTWvITnqtsIimZNbZd61XZNuTT7JdXyszOYFY nlJMifjThgw+w7+kHxFAGI9rsKGHFZiapxKPIT9UgVfmIY7Z1W4SfmRcJ0f949TUTHjY kJ7J6GTkKlxSiM3vvdzlv8EjThPKbQMKMYMzo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=pPkkayMqoY404hwMIWti3s+tl9smeoH8DKQs1LSa8V4=; b=Y2KkhulXF04YmGc2kHLLlM9sGt8LPTtiHJ0A9mYrKVprn0agN/CD8Orl8cWJdTX7Sv zV7nL/qhUZiIl2AbVwVA5B6nXkiBtXADJ5LUCiKW2HrdKL6EB3MyUdmULJnC+GZEMYNy D2BMlYqaV0+bWL6OBqlBpi8Ywd7S1/cXgR3DDfPf18BjV/yoR7pLlX6spi9L0FnmEFLR JBhx2Hco1gVDwmiDdkKyvPNLsEtJMP6Lo89PKsyYXuXyhkbs8f1T2pdTu/YrJowF/MBh AD7E5kLclBhIgjF0AqqWqh7VHdv/5DOVjetM1d/GcT9ZStyDbvvA0AqzvM5h30dLfxfK cdXw== X-Gm-Message-State: APjAAAVfIb4ima7D6bmceCVOtQ0a9oY15JzJyZ0qQyxsYGbpwRk6v4s0 p+zGdYOX5qlRq/n1/ksSyPJmXg== X-Google-Smtp-Source: APXvYqx8F4gmAh17IOiAHcyqfmcB4I8c278zpNEdGxnNwMArdEe2yyt01GfDbRva8CjnkY0S1x2NkA== X-Received: by 2002:a7b:c93a:: with SMTP id h26mr4290073wml.83.1578662749896; Fri, 10 Jan 2020 05:25:49 -0800 (PST) Received: from localhost.localdomain ([2a06:98c0:1000:8250:51ce:3bcb:24c3:4be9]) by smtp.gmail.com with ESMTPSA id m10sm2204033wrx.19.2020.01.10.05.25.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jan 2020 05:25:49 -0800 (PST) From: Lorenz Bauer To: kafai@fb.com, Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Lorenz Bauer , Joe Stringer , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Cc: kernel-team@cloudflare.com Subject: [PATCH bpf v2] net: bpf: don't leak time wait and request sockets Date: Fri, 10 Jan 2020 13:23:36 +0000 Message-Id: <20200110132336.26099-1-lmb@cloudflare.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200109115749.12283-1-lmb@cloudflare.com> References: <20200109115749.12283-1-lmb@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 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 --- 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 42fd17c48c5f..41820ba0774c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5277,8 +5277,7 @@ __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; } } @@ -5315,8 +5314,7 @@ 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; } } @@ -5383,7 +5381,8 @@ 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