netdev - [PATCH 1/7] xfrm: don't check the default policy if the policy allows the packet

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Date: Tue, 16 May 2023 07:23:59 +0200
From: Steffen Klassert <steffen.klassert@...unet.com>
To: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>
CC: Herbert Xu <herbert@...dor.apana.org.au>, Steffen Klassert
	<steffen.klassert@...unet.com>, <netdev@...r.kernel.org>
Subject: [PATCH 1/7] xfrm: don't check the default policy if the policy allows the packet

From: Sabrina Dubroca <sd@...asysnail.net>

The current code doesn't let a simple "allow" policy counteract a
default policy blocking all incoming packets:

    ip x p setdefault in block
    ip x p a src 192.168.2.1/32 dst 192.168.2.2/32 dir in action allow

At this stage, we have an allow policy (with or without transforms)
for this packet. It doesn't matter what the default policy says, since
the policy we looked up lets the packet through. The case of a
blocking policy is already handled separately, so we can remove this
check.

Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/xfrm/xfrm_policy.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 5c61ec04b839..62be042f2ebc 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3712,12 +3712,6 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 		}
 		xfrm_nr = ti;
 
-		if (net->xfrm.policy_default[dir] == XFRM_USERPOLICY_BLOCK &&
-		    !xfrm_nr) {
-			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
-			goto reject;
-		}
-
 		if (npols > 1) {
 			xfrm_tmpl_sort(stp, tpp, xfrm_nr, family);
 			tpp = stp;
-- 
2.34.1