xtables: use match, target and data copy_to_user helpers in compat

Convert compat to copying entries, matches and targets one by one,
using the xt_match_to_user and xt_target_to_user helper functions.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/x_tables.c

@@ -619,17 +619,14 @@ int xt_compat_match_to_user(const struct xt_entry_match *m,
 	int off = xt_compat_match_offset(match);
 	u_int16_t msize = m->u.user.match_size - off;
 
-	if (copy_to_user(cm, m, sizeof(*cm)) ||
-	    put_user(msize, &cm->u.user.match_size) ||
-	    copy_to_user(cm->u.user.name, m->u.kernel.match->name,
-			 strlen(m->u.kernel.match->name) + 1))
+	if (XT_OBJ_TO_USER(cm, m, match, msize))
 		return -EFAULT;
 
 	if (match->compat_to_user) {
 		if (match->compat_to_user((void __user *)cm->data, m->data))
 			return -EFAULT;
 	} else {
-		if (copy_to_user(cm->data, m->data, msize - sizeof(*cm)))
+		if (XT_DATA_TO_USER(cm, m, match, msize - sizeof(*cm)))
 			return -EFAULT;
 	}
 
@@ -977,17 +974,14 @@ int xt_compat_target_to_user(const struct xt_entry_target *t,
 	int off = xt_compat_target_offset(target);
 	u_int16_t tsize = t->u.user.target_size - off;
 
-	if (copy_to_user(ct, t, sizeof(*ct)) ||
-	    put_user(tsize, &ct->u.user.target_size) ||
-	    copy_to_user(ct->u.user.name, t->u.kernel.target->name,
-			 strlen(t->u.kernel.target->name) + 1))
+	if (XT_OBJ_TO_USER(ct, t, target, tsize))
 		return -EFAULT;
 
 	if (target->compat_to_user) {
 		if (target->compat_to_user((void __user *)ct->data, t->data))
 			return -EFAULT;
 	} else {
-		if (copy_to_user(ct->data, t->data, tsize - sizeof(*ct)))
+		if (XT_DATA_TO_USER(ct, t, target, tsize - sizeof(*ct)))
 			return -EFAULT;
 	}