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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 91651C7618B for ; Fri, 26 Jul 2019 15:35:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6682A205F4 for ; Fri, 26 Jul 2019 15:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564155334; bh=WEWgZBMWZpb7cstM89+rbjqinGpcnfjpuZJMXkjP0e8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Vq0No2WeD6/QvMxVK+wcsTyQX5eaqKvHTkTpGIXrBa2dIepWfqOhbl8aRFTAMOhJr Cc6HJmEGVsHouoH2gW8LBlO8ec+WFt1/Wq0N/YVoDNGrijcwz2U2ibHZwj4dXFAmHO qgNd/o5PUji2LLsLasnns6P0yIOLAIW53B3TuBUE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389109AbfGZPcj (ORCPT ); Fri, 26 Jul 2019 11:32:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:47860 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387859AbfGZPci (ORCPT ); Fri, 26 Jul 2019 11:32:38 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 CDBBB22CBF; Fri, 26 Jul 2019 15:32:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564155157; bh=WEWgZBMWZpb7cstM89+rbjqinGpcnfjpuZJMXkjP0e8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MBXJxdg/IvMToauZGcYgF6c0fcGiN+QhECZZJ36+8xEP5+aTeJUAcQljgDB8Wry9s 37YW+gdEfhJx8z30UwsDetSfleF8/KFu+IGSZfm3AbJHdEVJIOpIGnTdvGWZ0rH5qm h23i3opyRtiwC9j46qjkm8bikO0xvMDzS9GWJtsY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Lawrence Brakmo , Neal Cardwell , "David S. Miller" Subject: [PATCH 4.19 21/50] tcp: fix tcp_set_congestion_control() use from bpf hook Date: Fri, 26 Jul 2019 17:24:56 +0200 Message-Id: <20190726152302.754694627@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190726152300.760439618@linuxfoundation.org> References: <20190726152300.760439618@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit 8d650cdedaabb33e85e9b7c517c0c71fcecc1de9 ] Neal reported incorrect use of ns_capable() from bpf hook. bpf_setsockopt(...TCP_CONGESTION...) -> tcp_set_congestion_control() -> ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) -> ns_capable_common() -> current_cred() -> rcu_dereference_protected(current->cred, 1) Accessing 'current' in bpf context makes no sense, since packets are processed from softirq context. As Neal stated : The capability check in tcp_set_congestion_control() was written assuming a system call context, and then was reused from a BPF call site. The fix is to add a new parameter to tcp_set_congestion_control(), so that the ns_capable() call is only performed under the right context. Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control") Signed-off-by: Eric Dumazet Cc: Lawrence Brakmo Reported-by: Neal Cardwell Acked-by: Neal Cardwell Acked-by: Lawrence Brakmo Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/tcp.h | 3 ++- net/core/filter.c | 2 +- net/ipv4/tcp.c | 4 +++- net/ipv4/tcp_cong.c | 6 +++--- 4 files changed, 9 insertions(+), 6 deletions(-) --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1054,7 +1054,8 @@ void tcp_get_default_congestion_control( void tcp_get_available_congestion_control(char *buf, size_t len); void tcp_get_allowed_congestion_control(char *buf, size_t len); int tcp_set_allowed_congestion_control(char *allowed); -int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); +int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, + bool reinit, bool cap_net_admin); u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3991,7 +3991,7 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_so TCP_CA_NAME_MAX-1)); name[TCP_CA_NAME_MAX-1] = 0; ret = tcp_set_congestion_control(sk, name, false, - reinit); + reinit, true); } else { struct tcp_sock *tp = tcp_sk(sk); --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2729,7 +2729,9 @@ static int do_tcp_setsockopt(struct sock name[val] = 0; lock_sock(sk); - err = tcp_set_congestion_control(sk, name, true, true); + err = tcp_set_congestion_control(sk, name, true, true, + ns_capable(sock_net(sk)->user_ns, + CAP_NET_ADMIN)); release_sock(sk); return err; } --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -332,7 +332,8 @@ out: * tcp_reinit_congestion_control (if the current congestion control was * already initialized. */ -int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit) +int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, + bool reinit, bool cap_net_admin) { struct inet_connection_sock *icsk = inet_csk(sk); const struct tcp_congestion_ops *ca; @@ -368,8 +369,7 @@ int tcp_set_congestion_control(struct so } else { err = -EBUSY; } - } else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || - ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) { + } else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || cap_net_admin)) { err = -EPERM; } else if (!try_module_get(ca->owner)) { err = -EBUSY;