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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kai Lueke <kailueke@linux.microsoft.com>,
        Steffen Klassert <steffen.klassert@secunet.com>
Subject: [PATCH 4.19 01/57] Revert "xfrm: state and policy should fail if XFRMA_IF_ID 0"
Date:   Mon, 21 Mar 2022 14:51:42 +0100
Message-Id: <20220321133222.028331018@linuxfoundation.org>
In-Reply-To: <20220321133221.984120927@linuxfoundation.org>
References: <20220321133221.984120927@linuxfoundation.org>
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From: Kai Lueke <kailueke@linux.microsoft.com>

commit a3d9001b4e287fc043e5539d03d71a32ab114bcb upstream.

This reverts commit 68ac0f3810e76a853b5f7b90601a05c3048b8b54 because ID
0 was meant to be used for configuring the policy/state without
matching for a specific interface (e.g., Cilium is affected, see
https://github.com/cilium/cilium/pull/18789 and
https://github.com/cilium/cilium/pull/19019).

Signed-off-by: Kai Lueke <kailueke@linux.microsoft.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/xfrm/xfrm_user.c |   21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -620,13 +620,8 @@ static struct xfrm_state *xfrm_state_con
 
 	xfrm_smark_init(attrs, &x->props.smark);
 
-	if (attrs[XFRMA_IF_ID]) {
+	if (attrs[XFRMA_IF_ID])
 		x->if_id = nla_get_u32(attrs[XFRMA_IF_ID]);
-		if (!x->if_id) {
-			err = -EINVAL;
-			goto error;
-		}
-	}
 
 	err = __xfrm_init_state(x, false, attrs[XFRMA_OFFLOAD_DEV]);
 	if (err)
@@ -1332,13 +1327,8 @@ static int xfrm_alloc_userspi(struct sk_
 
 	mark = xfrm_mark_get(attrs, &m);
 
-	if (attrs[XFRMA_IF_ID]) {
+	if (attrs[XFRMA_IF_ID])
 		if_id = nla_get_u32(attrs[XFRMA_IF_ID]);
-		if (!if_id) {
-			err = -EINVAL;
-			goto out_noput;
-		}
-	}
 
 	if (p->info.seq) {
 		x = xfrm_find_acq_byseq(net, mark, p->info.seq);
@@ -1640,13 +1630,8 @@ static struct xfrm_policy *xfrm_policy_c
 
 	xfrm_mark_get(attrs, &xp->mark);
 
-	if (attrs[XFRMA_IF_ID]) {
+	if (attrs[XFRMA_IF_ID])
 		xp->if_id = nla_get_u32(attrs[XFRMA_IF_ID]);
-		if (!xp->if_id) {
-			err = -EINVAL;
-			goto error;
-		}
-	}
 
 	return xp;
  error: