xfrm: Refactor migration setup during the cloning process

Previously, migration related setup, such as updating family,
destination address, and source address, was performed after
the clone was created in `xfrm_state_migrate`. This change
moves this setup into the cloning function itself, improving
code locality and reducing redundancy.

The `xfrm_state_clone_and_setup` function now conditionally
applies the migration parameters from struct xfrm_migrate
if it is provided. This allows the function to be used both
for simple cloning and for cloning with migration setup.

Test: Tested with kernel test in the Android tree located
      in https://android.googlesource.com/kernel/tests/
      The xfrm_tunnel_test.py under the tests folder in
      particular.
Signed-off-by: Chiachang Wang <[email protected]>
Reviewed-by: Leon Romanovsky <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>

Author: Chiachang Wang

net/xfrm/xfrm_state.c

@@ -1958,8 +1958,9 @@ static inline int clone_security(struct xfrm_state *x, struct xfrm_sec_ctx *secu
 	return 0;
 }
 
-static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
-					   struct xfrm_encap_tmpl *encap)
+static struct xfrm_state *xfrm_state_clone_and_setup(struct xfrm_state *orig,
+					   struct xfrm_encap_tmpl *encap,
+					   struct xfrm_migrate *m)
 {
 	struct net *net = xs_net(orig);
 	struct xfrm_state *x = xfrm_state_alloc(net);
@@ -2058,6 +2059,11 @@ static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
 			goto error;
 	}
 
+
+	x->props.family = m->new_family;
+	memcpy(&x->id.daddr, &m->new_daddr, sizeof(x->id.daddr));
+	memcpy(&x->props.saddr, &m->new_saddr, sizeof(x->props.saddr));
+
 	return x;
 
  error:
@@ -2127,18 +2133,13 @@ struct xfrm_state *xfrm_state_migrate(struct xfrm_state *x,
 {
 	struct xfrm_state *xc;
 
-	xc = xfrm_state_clone(x, encap);
+	xc = xfrm_state_clone_and_setup(x, encap, m);
 	if (!xc)
 		return NULL;
 
-	xc->props.family = m->new_family;
-
 	if (xfrm_init_state(xc) < 0)
 		goto error;
 
-	memcpy(&xc->id.daddr, &m->new_daddr, sizeof(xc->id.daddr));
-	memcpy(&xc->props.saddr, &m->new_saddr, sizeof(xc->props.saddr));
-
 	/* configure the hardware if offload is requested */
 	if (xuo && xfrm_dev_state_add(net, xc, xuo, extack))
 		goto error;