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Subject[PATCH] xfrm: policy: Only use mark as policy lookup key
Date
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 ((policy->mark.v & policy->mark.m) == (pol->mark.v & pol->mark.m))
return true;

return false;
@@ -1628,7 +1622,7 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
hlist_for_each_entry(pol, chain, bydst) {
if (pol->type == type &&
pol->if_id == if_id &&
- (mark & pol->mark.m) == pol->mark.v &&
+ mark == (pol->mark.m & pol->mark.v) &&
!selector_cmp(sel, &pol->selector) &&
xfrm_sec_ctx_match(ctx, pol->security))
return pol;
@@ -1726,7 +1720,7 @@ struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u32 if_id,
hlist_for_each_entry(pol, chain, byidx) {
if (pol->type == type && pol->index == id &&
pol->if_id == if_id &&
- (mark & pol->mark.m) == pol->mark.v) {
+ mark == (pol->mark.m & pol->mark.v)) {
xfrm_pol_hold(pol);
if (delete) {
*err = security_xfrm_policy_delete(
@@ -1898,7 +1892,7 @@ static int xfrm_policy_match(const struct xfrm_policy *pol,

if (pol->family != family ||
pol->if_id != if_id ||
- (fl->flowi_mark & pol->mark.m) != pol->mark.v ||
+ fl->flowi_mark != (pol->mark.m & pol->mark.v) ||
pol->type != type)
return ret;

@@ -2177,7 +2171,7 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,

match = xfrm_selector_match(&pol->selector, fl, family);
if (match) {
- if ((sk->sk_mark & pol->mark.m) != pol->mark.v ||
+ if (sk->sk_mark != (pol->mark.m & pol->mark.v) ||
pol->if_id != if_id) {
pol = NULL;
goto out;
--
1.8.3.1

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