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Date: Sat, 23 May 2020 17:02:38 +0800 From: Xin Long <lucien.xin@...il.com> To: Yuehaibing <yuehaibing@...wei.com> Cc: Steffen Klassert <steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>, davem <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, network dev <netdev@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2] xfrm: policy: Fix xfrm policy match On Fri, May 22, 2020 at 8:39 PM Yuehaibing <yuehaibing@...wei.com> wrote: > > On 2020/5/22 13:49, Xin Long wrote: > > On Fri, May 22, 2020 at 9:45 AM Yuehaibing <yuehaibing@...wei.com> wrote: > >> > >> On 2020/5/21 14:49, Xin Long wrote: > >>> On Tue, May 19, 2020 at 4:53 PM Steffen Klassert > >>> <steffen.klassert@...unet.com> wrote: > >>>> > >>>> On Fri, May 15, 2020 at 04:39:57PM +0800, Yuehaibing wrote: > >>>>> > >>>>> Friendly ping... > >>>>> > >>>>> Any plan for this issue? > >>>> > >>>> There was still no consensus between you and Xin on how > >>>> to fix this issue. Once this happens, I consider applying > >>>> a fix. > >>>> > >>> Sorry, Yuehaibing, I can't really accept to do: (A->mark.m & A->mark.v) > >>> I'm thinking to change to: > >>> > >>> 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 (policy->mark.v == pol->mark.v && > >>> + (policy->mark.m == pol->mark.m || > >>> + policy->priority == pol->priority)) > >>> return true; > >>> > >>> return false; > >>> > >>> which means we consider (the same value and mask) or > >>> (the same value and priority) as the same one. This will > >>> cover both problems. > >> > >> policy A (mark.v = 0x1011, mark.m = 0x1011, priority = 1) > >> policy B (mark.v = 0x1001, mark.m = 0x1001, priority = 1) > > I'd think these are 2 different policies. > > > >> > >> when fl->flowi_mark == 0x12341011, in xfrm_policy_match() do check like this: > >> > >> (fl->flowi_mark & pol->mark.m) != pol->mark.v > >> > >> 0x12341011 & 0x1011 == 0x00001011 > >> 0x12341011 & 0x1001 == 0x00001001 > >> > >> This also match different policy depends on the order of policy inserting. > > Yes, this may happen when a user adds 2 policies like that. > > But I think this's a problem that the user doesn't configure it well, > > 'priority' should be set. > > and this can not be avoided, also such as: > > > > policy A (mark.v = 0xff00, mark.m = 0x1000, priority = 1) > > policy B (mark.v = 0x00ff, mark.m = 0x0011, priority = 1) > > > > try with 0x12341011 > > > > So just be it, let users decide. > > Ok, this make sense. Thanks Yuehaibing, it's good we're on the same page now. Just realized the patch I created above won't work for the case: policy A (mark.v = 0x10, mark.m = 0, priority = 1) policy B (mark.v = 0x1, mark.m = 0, priority = 2) policy C (mark.v = 0x10, mark.m = 0, priority = 2) when policy C is being added, the warning still occurs. So I will just check value and priority: - 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 == pol->mark.v && policy->priority == pol->priority) return true; This allows two policies like this exist: policy A (mark.v = 0x10, mark.m = 0, priority = 1) policy C (mark.v = 0x10, mark.m = 0, priority = 2) But I don't think it's a problem.
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