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=-5.7 required=3.0 tests=DATE_IN_PAST_03_06, DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, 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 66254C2D0DB for ; Wed, 22 Jan 2020 13:23:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A91D205F4 for ; Wed, 22 Jan 2020 13:23:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579699407; bh=TMn3jYVlQc/Uk2+dQ9IlqD8wZaLCV/tfllBc2wf93Oo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iE6GgTZY9ISKx6RRn0vDY4BWy4ml/uoE91ymypDwcGs/LJ+YmOA0QdviwNwK5MRum lgq4w6PrN7LBo0GekKed8iRO9QECKx3jgbds2T5pj7wkecTpuiEutPl9dzIz2JmQ4i l9diTDvN88Fv6WPXWofUcazxJ4kIoSHID7OzRWFo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730381AbgAVNX0 (ORCPT ); Wed, 22 Jan 2020 08:23:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:41526 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730728AbgAVNXW (ORCPT ); Wed, 22 Jan 2020 08:23:22 -0500 Received: from localhost (unknown [84.241.205.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2105B205F4; Wed, 22 Jan 2020 13:23:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579699401; bh=TMn3jYVlQc/Uk2+dQ9IlqD8wZaLCV/tfllBc2wf93Oo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lIdv+fskmKw9JOk0WeJHB9rXmSoV1+gWeT7E9umKgfOumZnQ0RZl/Lrua47COOFeo t0bV6Dh3kw1Cgf8XOPGUhunHHTPcuhMPOB5h3aeD9k6zZIDoNKkxaQ/U9ZlFI1CCyY 2fhiXgWlz7rXhK9/RHtmXXxHpFo7baPf0WA8iFbI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lorenz Bauer , Alexei Starovoitov , Martin KaFai Lau Subject: [PATCH 5.4 133/222] net: bpf: Dont leak time wait and request sockets Date: Wed, 22 Jan 2020 10:28:39 +0100 Message-Id: <20200122092843.267838496@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092833.339495161@linuxfoundation.org> References: <20200122092833.339495161@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 commit 2e012c74823629d9db27963c79caa3f5b2010746 upstream. 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: Greg Kroah-Hartman --- net/core/filter.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5306,8 +5306,7 @@ __bpf_sk_lookup(struct sk_buff *skb, str 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; } } @@ -5344,8 +5343,7 @@ bpf_sk_lookup(struct sk_buff *skb, struc 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; } } @@ -5412,7 +5410,8 @@ static const struct bpf_func_proto bpf_s 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; }