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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 DB507C2BA19 for ; Thu, 23 Apr 2020 08:41:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1FD220781 for ; Thu, 23 Apr 2020 08:41:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726847AbgDWIlE (ORCPT ); Thu, 23 Apr 2020 04:41:04 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:2840 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725854AbgDWIlD (ORCPT ); Thu, 23 Apr 2020 04:41:03 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 4D94C6AD35676552E2D7; Thu, 23 Apr 2020 16:41:00 +0800 (CST) Received: from [127.0.0.1] (10.166.215.154) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Thu, 23 Apr 2020 16:40:54 +0800 Subject: Re: [PATCH] xfrm: policy: Only use mark as policy lookup key To: Xin Long References: <20200421143149.45108-1-yuehaibing@huawei.com> <20200422093344.GY13121@gauss3.secunet.de> <1650fd55-dd70-f687-88b6-d32a04245915@huawei.com> <02a56d2c-8d27-f53a-d9e3-c25bd03677c8@huawei.com> CC: Steffen Klassert , Herbert Xu , davem , , network dev , LKML , Jamal Hadi Salim From: Yuehaibing Message-ID: Date: Thu, 23 Apr 2020 16:40:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.166.215.154] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/4/23 14:37, Xin Long wrote: > On Thu, Apr 23, 2020 at 10:26 AM Yuehaibing wrote: >> >> On 2020/4/22 23:41, Xin Long wrote: >>> On Wed, Apr 22, 2020 at 8:18 PM Yuehaibing wrote: >>>> >>>> On 2020/4/22 17:33, Steffen Klassert wrote: >>>>> On Tue, Apr 21, 2020 at 10:31:49PM +0800, YueHaibing wrote: >>>>>> While update xfrm policy as follow: >>>>>> >>>>>> ip -6 xfrm policy update src fd00::1/128 dst fd00::2/128 dir in \ >>>>>> priority 1 mark 0 mask 0x10 >>>>>> ip -6 xfrm policy update src fd00::1/128 dst fd00::2/128 dir in \ >>>>>> priority 2 mark 0 mask 0x00 >>>>>> ip -6 xfrm policy update src fd00::1/128 dst fd00::2/128 dir in \ >>>>>> priority 2 mark 0 mask 0x10 >>>>>> >>>>>> We get this warning: >>>>>> >>>>>> WARNING: CPU: 0 PID: 4808 at net/xfrm/xfrm_policy.c:1548 >>>>>> Kernel panic - not syncing: panic_on_warn set ... >>>>>> CPU: 0 PID: 4808 Comm: ip Not tainted 5.7.0-rc1+ #151 >>>>>> Call Trace: >>>>>> RIP: 0010:xfrm_policy_insert_list+0x153/0x1e0 >>>>>> xfrm_policy_inexact_insert+0x70/0x330 >>>>>> xfrm_policy_insert+0x1df/0x250 >>>>>> xfrm_add_policy+0xcc/0x190 [xfrm_user] >>>>>> xfrm_user_rcv_msg+0x1d1/0x1f0 [xfrm_user] >>>>>> netlink_rcv_skb+0x4c/0x120 >>>>>> xfrm_netlink_rcv+0x32/0x40 [xfrm_user] >>>>>> netlink_unicast+0x1b3/0x270 >>>>>> netlink_sendmsg+0x350/0x470 >>>>>> sock_sendmsg+0x4f/0x60 >>>>>> >>>>>> Policy C and policy A has the same mark.v and mark.m, so policy A is >>>>>> matched in first round lookup while updating C. However policy C and >>>>>> policy B has same mark and priority, which also leads to matched. So >>>>>> the WARN_ON is triggered. >>>>>> >>>>>> xfrm policy lookup should only be matched when the found policy has the >>>>>> same lookup keys (mark.v & mark.m) no matter priority. >>>>>> >>>>>> Fixes: 7cb8a93968e3 ("xfrm: Allow inserting policies with matching mark and different priorities") >>>>>> Signed-off-by: YueHaibing >>>>>> --- >>>>>> net/xfrm/xfrm_policy.c | 16 +++++----------- >>>>>> 1 file changed, 5 insertions(+), 11 deletions(-) >>>>>> >>>>>> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c >>>>>> index 297b2fd..67d0469 100644 >>>>>> --- a/net/xfrm/xfrm_policy.c >>>>>> +++ b/net/xfrm/xfrm_policy.c >>>>>> @@ -1436,13 +1436,7 @@ static void xfrm_policy_requeue(struct xfrm_policy *old, >>>>>> static bool xfrm_policy_mark_match(struct xfrm_policy *policy, >>>>>> struct xfrm_policy *pol) >>>>>> { >>>>>> - u32 mark = policy->mark.v & policy->mark.m; >>>>>> - >>>>>> - if (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m) >>>>>> - return true; >>>>>> - >>>>>> - if ((mark & pol->mark.m) == pol->mark.v && >>>>>> - policy->priority == pol->priority) >>>>> >>>>> If you remove the priority check, you can't insert policies with matching >>>>> mark and different priorities anymore. This brings us back the old bug. >>>> >>>> Yes, this is true. >>>> >>>>> >>>>> I plan to apply the patch from Xin Long, this seems to be the right way >>>>> to address this problem. >>>> >>>> That still brings an issue, update like this: >>>> >>>> policy A (mark.v = 1, mark.m = 0, priority = 1) >>>> policy B (mark.v = 1, mark.m = 0, priority = 1) >>>> >>>> A and B will all in the list. >>> I think this is another issue even before: >>> 7cb8a93968e3 ("xfrm: Allow inserting policies with matching mark and >>> different priorities") >>> >>>> >>>> So should do this: >>>> >>>> static bool xfrm_policy_mark_match(struct xfrm_policy *policy, >>>> struct xfrm_policy *pol) >>>> { >>>> - u32 mark = policy->mark.v & policy->mark.m; >>>> - >>>> - if (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m) >>>> - return true; >>>> - >>>> - if ((mark & pol->mark.m) == pol->mark.v && >>>> + if ((policy->mark.v & policy->mark.m) == (pol->mark.v & pol->mark.m) && >>>> policy->priority == pol->priority) >>>> return true; >>> "mark.v & mark.m" looks weird to me, it should be: >>> ((something & mark.m) == mark.v) >>> >>> So why should we just do this here?: >>> (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m && >>> policy->priority == pol->priority) >> >> >> This leads to this issue: >> >> ip -6 xfrm policy add src fd00::1/128 dst fd00::2/128 dir in mark 0x00000001 mask 0x00000005 >> ip -6 xfrm policy add src fd00::1/128 dst fd00::2/128 dir in mark 0x00000001 mask 0x00000003 >> >> the two policies will be in list, which should not be allowed. > I think these are two different policies. > For instance: > mark = 0x1234567b will match the 1st one only. > mark = 0x1234567d will match the 2st one only > > So these should have been allowed, no? If mark = 0x12345671, it may match different policy depends on the order of inserting, ip xfrm policy update src 172.16.2.0/24 dst 172.16.1.0/24 dir in ptype main \ tmpl src 192.168.2.10 dst 192.168.1.20 proto esp mode tunnel mark 0x00000001 mask 0x00000005 ip xfrm policy update src 172.16.2.0/24 dst 172.16.1.0/24 dir in ptype main \ tmpl src 192.168.2.100 dst 192.168.1.100 proto esp mode beet mark 0x00000001 mask 0x00000003 In fact, your case should use different priority to match. > > I'm actually confused now. > does the mask work against its own value, or the other value? > as 'A == (mark.v&mark.m)' and '(A & mark.m) == mark.v' are different things. > > This can date back to Jamal's xfrm by MARK: > > https://lwn.net/Articles/375829/ > > where it does 'm->v & m->m' in xfrm_mark_get() and > 'policy->mark.v & policy->mark.m' in xfrm_policy_insert() while > it does '(A & pol->mark.m) == pol->mark.v' in other places. > > Now I'm thinking 'm->v & m->m' is meaningless, by which if we get > a value != m->v, it means this mark can never be matched by any. > > policy A (mark.v = 1, mark.m = 0, priority = 1) > policy B (mark.v = 1, mark.m = 0, priority = 1) > > So probably we should avoid this case by check m->v == (m->v & m->m) > when adding a new policy. > > wdyt? >