[PATCH 2/3] xfrm: skip templates check for packet offload tunnel mode

[Steffen Klassert <steffen.klassert@secunet.com>]

From: Leon Romanovsky <leonro@nvidia.com>

In packet offload, hardware is responsible to check templates. The
result of its operation is forwarded through secpath by relevant
drivers. That secpath is actually removed in __xfrm_policy_check2().

In case packet is forwarded, this secpath is reset in RX, but pushed
again to TX where policy is rechecked again against dummy secpath
in xfrm_policy_ok().

Such situation causes to unexpected XfrmInTmplMismatch increase.

As a solution, simply skip template mismatch check.

Fixes: 600258d555f0 ("xfrm: delete intermediate secpath entry in packet offload mode")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Jianbo Liu <jianbol@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_policy.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 62486f866975..5428185196a1 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3801,8 +3801,8 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 		struct xfrm_tmpl *tp[XFRM_MAX_DEPTH];
 		struct xfrm_tmpl *stp[XFRM_MAX_DEPTH];
 		struct xfrm_tmpl **tpp = tp;
+		int i, k = 0;
 		int ti = 0;
-		int i, k;
 
 		sp = skb_sec_path(skb);
 		if (!sp)
@@ -3828,6 +3828,12 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 			tpp = stp;
 		}
 
+		if (pol->xdo.type == XFRM_DEV_OFFLOAD_PACKET && sp == &dummy)
+			/* This policy template was already checked by HW
+			 * and secpath was removed in __xfrm_policy_check2.
+			 */
+			goto out;
+
 		/* For each tunnel xfrm, find the first matching tmpl.
 		 * For each tmpl before that, find corresponding xfrm.
 		 * Order is _important_. Later we will implement
@@ -3837,7 +3843,7 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 		 * verified to allow them to be skipped in future policy
 		 * checks (e.g. nested tunnels).
 		 */
-		for (i = xfrm_nr-1, k = 0; i >= 0; i--) {
+		for (i = xfrm_nr - 1; i >= 0; i--) {
 			k = xfrm_policy_ok(tpp[i], sp, k, family, if_id);
 			if (k < 0) {
 				if (k < -1)
@@ -3853,6 +3859,7 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 			goto reject;
 		}
 
+out:
 		xfrm_pols_put(pols, npols);
 		sp->verified_cnt = k;
 
-- 
2.43.0