xfrm: clone XFRMA_SEC_CTX in xfrm_do_migrate

XFRMA_SEC_CTX was not cloned from the old to the new.
Migrate this attribute during XFRMA_MSG_MIGRATE

v1->v2:
 - return -ENOMEM on error
v2->v3:
 - fix return type to int

Fixes: 80c9abaa ("[XFRM]: Extension for dynamic update of endpoint address(es)")
Signed-off-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_state.c

@@ -1441,6 +1441,30 @@ int xfrm_state_add(struct xfrm_state *x)
 EXPORT_SYMBOL(xfrm_state_add);
 
 #ifdef CONFIG_XFRM_MIGRATE
+static inline int clone_security(struct xfrm_state *x, struct xfrm_sec_ctx *security)
+{
+	struct xfrm_user_sec_ctx *uctx;
+	int size = sizeof(*uctx) + security->ctx_len;
+	int err;
+
+	uctx = kmalloc(size, GFP_KERNEL);
+	if (!uctx)
+		return -ENOMEM;
+
+	uctx->exttype = XFRMA_SEC_CTX;
+	uctx->len = size;
+	uctx->ctx_doi = security->ctx_doi;
+	uctx->ctx_alg = security->ctx_alg;
+	uctx->ctx_len = security->ctx_len;
+	memcpy(uctx + 1, security->ctx_str, security->ctx_len);
+	err = security_xfrm_state_alloc(x, uctx);
+	kfree(uctx);
+	if (err)
+		return err;
+
+	return 0;
+}
+
 static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
 					   struct xfrm_encap_tmpl *encap)
 {
@@ -1497,6 +1521,10 @@ static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
 			goto error;
 	}
 
+	if (orig->security)
+		if (clone_security(x, orig->security))
+			goto error;
+
 	if (orig->coaddr) {
 		x->coaddr = kmemdup(orig->coaddr, sizeof(*x->coaddr),
 				    GFP_KERNEL);