[PATCH 1/2] Revert "xfrm: interface with if_id 0 should return error"

[kailueke@linux.microsoft.com]

From: Kai Lueke <kailueke@linux.microsoft.com>

This reverts commit 8dce43919566f06e865f7e8949f5c10d8c2493f5 because it
breaks userspace (e.g., Cilium is affected because it used id 0 for the
dummy state https://github.com/cilium/cilium/pull/18789).

Signed-off-by: Kai Lueke <kailueke@linux.microsoft.com>
---
 net/xfrm/xfrm_interface.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index 57448fc519fc..41de46b5ffa9 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -637,16 +637,11 @@ static int xfrmi_newlink(struct net *src_net, struct net_device *dev,
 			struct netlink_ext_ack *extack)
 {
 	struct net *net = dev_net(dev);
-	struct xfrm_if_parms p = {};
+	struct xfrm_if_parms p;
 	struct xfrm_if *xi;
 	int err;
 
 	xfrmi_netlink_parms(data, &p);
-	if (!p.if_id) {
-		NL_SET_ERR_MSG(extack, "if_id must be non zero");
-		return -EINVAL;
-	}
-
 	xi = xfrmi_locate(net, &p);
 	if (xi)
 		return -EEXIST;
@@ -671,12 +666,7 @@ static int xfrmi_changelink(struct net_device *dev, struct nlattr *tb[],
 {
 	struct xfrm_if *xi = netdev_priv(dev);
 	struct net *net = xi->net;
-	struct xfrm_if_parms p = {};
-
-	if (!p.if_id) {
-		NL_SET_ERR_MSG(extack, "if_id must be non zero");
-		return -EINVAL;
-	}
+	struct xfrm_if_parms p;
 
 	xfrmi_netlink_parms(data, &p);
 	xi = xfrmi_locate(net, &p);
-- 
2.25.1