Messages in this thread | | | Subject | Re: [PATCH] xfrm: policy: Only use mark as policy lookup key | From | Yuehaibing <> | Date | Thu, 23 Apr 2020 10:25:58 +0800 |
| |
On 2020/4/22 23:41, Xin Long wrote: > On Wed, Apr 22, 2020 at 8:18 PM Yuehaibing <yuehaibing@huawei.com> 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 <yuehaibing@huawei.com> >>>> --- >>>> 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.
> >> >> >> >>> >>> . >>> >> > > . >
| |