From patchwork Wed May 20 17:22:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Sitnicki X-Patchwork-Id: 1294505 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=cloudflare.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=cloudflare.com header.i=@cloudflare.com header.a=rsa-sha256 header.s=google header.b=NZdH7cfi; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49S02L3Gcgz9sSf for ; Thu, 21 May 2020 03:23:06 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbgETRXF (ORCPT ); Wed, 20 May 2020 13:23:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728310AbgETRXB (ORCPT ); Wed, 20 May 2020 13:23:01 -0400 Received: from mail-ej1-x642.google.com (mail-ej1-x642.google.com [IPv6:2a00:1450:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90789C061A0E for ; Wed, 20 May 2020 10:23:01 -0700 (PDT) Received: by mail-ej1-x642.google.com with SMTP id s3so4946765eji.6 for ; Wed, 20 May 2020 10:23:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=hdoJULNF4ZOJn60TD6kq6HAcbNwe48XKEyzovvw9zBM=; b=NZdH7cfivutOeU4FSA3YHpO8Jv+24jr8nQan6NAgtMW8ZiRyjVMir7fkvhMc1XXsYR 6ufQDdFSFcx4iNqVhx0RMnJVyFiSGyd+rN4ww7nmzsL/uiOZwvQEZvQr0Z08TxeBq1I1 YJs9NV8bdYa8OEhl0mZ1WlwLQEHGF5y2+zQaE= 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:mime-version :content-transfer-encoding; bh=hdoJULNF4ZOJn60TD6kq6HAcbNwe48XKEyzovvw9zBM=; b=cqiKFhhmchKuZ2scsDJ22Zlav08LkKsuqznj6Ok6S5g7R7xl80n/c3ADNSVdNS4F2H AoFkkue0uhya/TMXrGCrF7weWyIH/hmYix82jViR80nqo+Z1A3kHPnE2Z/oMlN2yLjeN wWBpSXktH3NqvZJXubahSqHpqgwnxitwHkJyFSN82kZC7IYWrUTtc3jKdxtY7EY/wauJ x2Dk/GHIo2GTcxNqbw8gWjV2c9GWV20RT6LdJ2rLybMSJ2HqzZa5HdmssMxdJK07hlEJ 7QD52D3J+eDOryuv8M+ZCMuKZUZjpQFh10qmwBZ65WBnqY3a1SJTkPniq+9YQ3lesV7K qh5w== X-Gm-Message-State: AOAM530VrOB3m2DF3glIKZxzZGVO0xl+ykjClPibvWbJjJObxD4vzQVG mXHiilsQGh9LXgVpnrAfGnIm+w== X-Google-Smtp-Source: ABdhPJyhxTaCSaNGLZWJp3O4t2hlLyWcJoLESAkuHR0YN6yqSYE1E6EuiY8a3ngY9CI7PP0tluCGfA== X-Received: by 2002:a17:906:580e:: with SMTP id m14mr76000ejq.447.1589995380253; Wed, 20 May 2020 10:23:00 -0700 (PDT) Received: from cloudflare.com ([2a02:a310:c262:aa00:b35e:8938:2c2a:ba8b]) by smtp.gmail.com with ESMTPSA id j26sm2425763ejc.118.2020.05.20.10.22.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2020 10:22:59 -0700 (PDT) From: Jakub Sitnicki To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, kernel-team@cloudflare.com, Petar Penkov , Stanislav Fomichev Subject: [PATCH bpf] flow_dissector: Drop BPF flow dissector prog ref on netns cleanup Date: Wed, 20 May 2020 19:22:58 +0200 Message-Id: <20200520172258.551075-1-jakub@cloudflare.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 --- Discovered while working on bpf_link support for netns-attached progs. Looks like bpf tree material so pushing it out separately. -jkbs net/core/flow_dissector.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 3eff84824c8b..b6179cd20158 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -179,6 +179,27 @@ int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) return 0; } +static void __net_exit flow_dissector_pernet_pre_exit(struct net *net) +{ + struct bpf_prog *attached; + + /* We don't lock the update-side because there are no + * references left to this netns when we get called. Hence + * there can be no attach/detach in progress. + */ + rcu_read_lock(); + attached = rcu_dereference(net->flow_dissector_prog); + if (attached) { + RCU_INIT_POINTER(net->flow_dissector_prog, NULL); + bpf_prog_put(attached); + } + rcu_read_unlock(); +} + +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 @@ -1827,6 +1848,8 @@ EXPORT_SYMBOL(flow_keys_basic_dissector); static int __init init_default_flow_dissectors(void) { + int err; + skb_flow_dissector_init(&flow_keys_dissector, flow_keys_dissector_keys, ARRAY_SIZE(flow_keys_dissector_keys)); @@ -1836,7 +1859,11 @@ 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; + + err = register_pernet_subsys(&flow_dissector_pernet_ops); + + WARN_ON(err); + return err; } core_initcall(init_default_flow_dissectors);