xfrm: Check if_id in xfrm_migrate

This patch enables distinguishing SAs and SPs based on if_id during
the xfrm_migrate flow. This ensures support for xfrm interfaces
throughout the SA/SP lifecycle.

When there are multiple existing SPs with the same direction,
the same xfrm_selector and different endpoint addresses,
xfrm_migrate might fail with ENODATA.

Specifically, the code path for performing xfrm_migrate is:
  Stage 1: find policy to migrate with
    xfrm_migrate_policy_find(sel, dir, type, net)
  Stage 2: find and update state(s) with
    xfrm_migrate_state_find(mp, net)
  Stage 3: update endpoint address(es) of template(s) with
    xfrm_policy_migrate(pol, m, num_migrate)

Currently "Stage 1" always returns the first xfrm_policy that
matches, and "Stage 3" looks for the xfrm_tmpl that matches the
old endpoint address. Thus if there are multiple xfrm_policy
with same selector, direction, type and net, "Stage 1" might
rertun a wrong xfrm_policy and "Stage 3" will fail with ENODATA
because it cannot find a xfrm_tmpl with the matching endpoint
address.

The fix is to allow userspace to pass an if_id and add if_id
to the matching rule in Stage 1 and Stage 2 since if_id is a
unique ID for xfrm_policy and xfrm_state. For compatibility,
if_id will only be checked if the attribute is set.

Tested with additions to Android's kernel unit test suite:
https://android-review.googlesource.com/c/kernel/tests/+/1668886

Signed-off-by: Yan Yan <evitayan@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/key/af_key.c b/net/key/af_key.c
index de24a7d474df..9bf52a09b5ff 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2623,7 +2623,7 @@ static int pfkey_migrate(struct sock *sk, struct sk_buff *skb,
 	}
 
 	return xfrm_migrate(&sel, dir, XFRM_POLICY_TYPE_MAIN, m, i,
-			    kma ? &k : NULL, net, NULL);
+			    kma ? &k : NULL, net, NULL, 0);
 
  out:
 	return err;