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,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 1233CC433E3 for ; Tue, 9 Jun 2020 00:29:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3D3A2078B for ; Tue, 9 Jun 2020 00:29:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591662577; bh=GYCIRJadqCjtngCxpF39DU3VLAgOV9p5ZuU8EFPmBRQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kO36c/crn5iAIFfSVCMdALlNhl8gxytbaanyw66E5ycd7sAFhIRn3ZnemtactpWt9 n9BFBDnpNa9cDwKNe2JD6djFxjhOkvozenrwtE4WLtXKZh8UAx4KkOzZDUNX6/swUP d3kbU0MK252Y6wGDmRUf+UgX3tfONwuHCRQcMOqM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731209AbgFIA3E (ORCPT ); Mon, 8 Jun 2020 20:29:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:37500 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730188AbgFHXQM (ORCPT ); Mon, 8 Jun 2020 19:16:12 -0400 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 081222076C; Mon, 8 Jun 2020 23:16:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658171; bh=GYCIRJadqCjtngCxpF39DU3VLAgOV9p5ZuU8EFPmBRQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f+6EALdU7eNA1mZXNXw3+u3DH0+tJl9DOMsWtGMxBx5EmWhgZmoAfeCB2glw4+vbq aJO2U8a1RPl/a3yF0hr8Ab1lmUzhJNoF5kF2pFo5ttE2r/2pCoCa6Xs54PpEDeVkLP yD+38i2PwbGv9Lst42OrRXiv09IBXopQQzuU1psY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jakub Sitnicki , Alexei Starovoitov , Stanislav Fomichev , Greg Kroah-Hartman , netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH AUTOSEL 5.6 198/606] flow_dissector: Drop BPF flow dissector prog ref on netns cleanup Date: Mon, 8 Jun 2020 19:05:23 -0400 Message-Id: <20200608231211.3363633-198-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org> References: <20200608231211.3363633-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Jakub Sitnicki commit 5cf65922bb15279402e1e19b5ee8c51d618fa51f upstream. When attaching a flow dissector program to a network namespace with bpf(BPF_PROG_ATTACH, ...) we grab a reference to bpf_prog. If netns gets destroyed while a flow dissector is still attached, and there are no other references to the prog, we leak the reference and the program remains loaded. Leak can be reproduced by running flow dissector tests from selftests/bpf: # bpftool prog list # ./test_flow_dissector.sh ... selftests: test_flow_dissector [PASS] # bpftool prog list 4: flow_dissector name _dissect tag e314084d332a5338 gpl loaded_at 2020-05-20T18:50:53+0200 uid 0 xlated 552B jited 355B memlock 4096B map_ids 3,4 btf_id 4 # Fix it by detaching the flow dissector program when netns is going away. Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Signed-off-by: Jakub Sitnicki Signed-off-by: Alexei Starovoitov Reviewed-by: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20200521083435.560256-1-jakub@cloudflare.com Signed-off-by: Greg Kroah-Hartman --- net/core/flow_dissector.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index a1670dff0629..0e5012d7b7b5 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -160,12 +160,10 @@ int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr, return ret; } -int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) +static int flow_dissector_bpf_prog_detach(struct net *net) { struct bpf_prog *attached; - struct net *net; - net = current->nsproxy->net_ns; mutex_lock(&flow_dissector_mutex); attached = rcu_dereference_protected(net->flow_dissector_prog, lockdep_is_held(&flow_dissector_mutex)); @@ -179,6 +177,24 @@ int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) return 0; } +int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) +{ + return flow_dissector_bpf_prog_detach(current->nsproxy->net_ns); +} + +static void __net_exit flow_dissector_pernet_pre_exit(struct net *net) +{ + /* We're not racing with attach/detach because there are no + * references to netns left when pre_exit gets called. + */ + if (rcu_access_pointer(net->flow_dissector_prog)) + flow_dissector_bpf_prog_detach(net); +} + +static struct pernet_operations flow_dissector_pernet_ops __net_initdata = { + .pre_exit = flow_dissector_pernet_pre_exit, +}; + /** * __skb_flow_get_ports - extract the upper layer ports and return them * @skb: sk_buff to extract the ports from @@ -1838,7 +1854,7 @@ static int __init init_default_flow_dissectors(void) skb_flow_dissector_init(&flow_keys_basic_dissector, flow_keys_basic_dissector_keys, ARRAY_SIZE(flow_keys_basic_dissector_keys)); - return 0; -} + return register_pernet_subsys(&flow_dissector_pernet_ops); +} core_initcall(init_default_flow_dissectors); -- 2.25.1