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 77F4EC32771 for ; Thu, 9 Jan 2020 11:58:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F48820656 for ; Thu, 9 Jan 2020 11:58:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="rk3alyzn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730334AbgAIL6r (ORCPT ); Thu, 9 Jan 2020 06:58:47 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:34671 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730263AbgAIL6q (ORCPT ); Thu, 9 Jan 2020 06:58:46 -0500 Received: by mail-wm1-f68.google.com with SMTP id w5so1885377wmi.1 for ; Thu, 09 Jan 2020 03:58:45 -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=1rlOVVzlIiRtFZks5/lLiUWPWerO848tJVKJUJDT+zo=; b=rk3alyznkOGmxU582kJxzO103S5dGuzlXwxudH2eHL4WS6/WCCkXg3TP+YrCAyChxF MHeftt7vdb+6pNDiBFb31TUxoKd78u49VkIbzbpqtRlnVNY0oMJ5Hxy81bvvgvUrSHYg k0U9/48D5/Ms1pRxZlC1J0br2Ut8/dkuu/1L4= 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=1rlOVVzlIiRtFZks5/lLiUWPWerO848tJVKJUJDT+zo=; b=AuqPGcWT5wKqHPC2dWWpFuhGI8ZZcpTA9Ltlw63wtLZV5KKTHFLcQ8vTZeiZDRBT+d 6EQg73CtEDkG691oMTZVzxcKVXQOrjhoQZgQt3/1zFEVCQpNxAbg3qdB9n8Sa7+4T8mF DqdjJhcLOstlaUBkU9BsM4apkRGglAGniZ80cmyOpvW5U3GZaClLSZH7FHklHWpNrqfX fBtTcw1MGeDwfcBitipg7Sb+Jnb+3w9o+ZaI8pDqI89+Rw+RNIYLfYzqB6C1sIGVlpwi nyCF/lSjJ107Hc9MdJD+Z/sIFZVvMiuKxnLYmocvwpnUuvYmyL5F6evFi31VNt6p0tL9 WcLQ== X-Gm-Message-State: APjAAAXYZ1wed6oue4Nx435eziwbut8YSEF7UzWZOUxP1E0xX5vSlbtY 0eYQvBz5HFD+J5sMAShxtMRKLw== X-Google-Smtp-Source: APXvYqyutNBniQQekS7aBd1mEWMPCgClEf647St5Ra0WHTPMf39/lT/e28kz3s4Dt8NwvdrM/7R+1Q== X-Received: by 2002:a7b:c30b:: with SMTP id k11mr4540527wmj.36.1578571125126; Thu, 09 Jan 2020 03:58:45 -0800 (PST) Received: from localhost.localdomain ([2a06:98c0:1000:8250:cd2c:908b:e15b:9937]) by smtp.gmail.com with ESMTPSA id z124sm2728120wmc.20.2020.01.09.03.58.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jan 2020 03:58:44 -0800 (PST) From: Lorenz Bauer To: Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Lorenz Bauer , Martin KaFai Lau , Joe Stringer , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Cc: kernel-team@cloudflare.com, edumazet@google.com Subject: [PATCH bpf 1/1] net: bpf: don't leak time wait and request sockets Date: Thu, 9 Jan 2020 11:57:48 +0000 Message-Id: <20200109115749.12283-2-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. Introduce a helper to account for this complication, and call it from the necessary places. 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 | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 42fd17c48c5f..d98dc4526d82 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5266,6 +5266,14 @@ __bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, return sk; } +static void __bpf_sk_release(struct sock *sk) +{ + /* time wait and request socks don't have sk_flags. */ + if (sk->sk_state == TCP_TIME_WAIT || sk->sk_state == TCP_NEW_SYN_RECV || + !sock_flag(sk, SOCK_RCU_FREE)) + sock_gen_put(sk); +} + static struct sock * __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id, @@ -5277,8 +5285,7 @@ __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); + __bpf_sk_release(sk); return NULL; } } @@ -5315,8 +5322,7 @@ 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); + __bpf_sk_release(sk); return NULL; } } @@ -5383,8 +5389,7 @@ 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)) - sock_gen_put(sk); + __bpf_sk_release(sk); return 0; } -- 2.20.1