[PATCH v1 net-next 6/6] fib: rules: Convert RTM_DELRULE to per-netns RTNL.

[Kuniyuki Iwashima <kuniyu@amazon.com>]

fib_nl_delrule() is the doit() handler for RTM_DELRULE but also called
1;95;0cfrom vrf_newlink() in case something fails in vrf_add_fib_rules().

In the latter case, RTNL is already held and the 3rd arg extack is NULL.

Let's hold per-netns RTNL in fib_nl_delrule() if extack is NULL.

Now we can place ASSERT_RTNL_NET() in call_fib_rule_notifiers().

While at it, fib_rule r is moved to the suitable scope.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/core/fib_rules.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index cc26c762fa9e..3430d026134d 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -371,7 +371,8 @@ static int call_fib_rule_notifiers(struct net *net,
 		.rule = rule,
 	};
 
-	ASSERT_RTNL();
+	ASSERT_RTNL_NET(net);
+
 	/* Paired with READ_ONCE() in fib_rules_seq() */
 	WRITE_ONCE(ops->fib_rules_seq, ops->fib_rules_seq + 1);
 	return call_fib_notifiers(net, event_type, &info.info);
@@ -909,13 +910,13 @@ EXPORT_SYMBOL_GPL(fib_nl_newrule);
 int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 		   struct netlink_ext_ack *extack)
 {
-	struct net *net = sock_net(skb->sk);
+	bool user_priority = false, hold_rtnl = !!extack;
+	struct fib_rule *rule = NULL, *nlrule = NULL;
 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
+	struct net *net = sock_net(skb->sk);
 	struct fib_rules_ops *ops = NULL;
-	struct fib_rule *rule = NULL, *r, *nlrule = NULL;
 	struct nlattr *tb[FRA_MAX+1];
 	int err = -EINVAL;
-	bool user_priority = false;
 
 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) {
 		NL_SET_ERR_MSG(extack, "Invalid msg length");
@@ -940,6 +941,9 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		goto errout;
 
+	if (hold_rtnl)
+		rtnl_net_lock(net);
+
 	err = fib_nl2rule_rtnl(nlrule, ops, tb, extack);
 	if (err)
 		goto errout_free;
@@ -980,7 +984,7 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	 * current if it is goto rule, have actually been added.
 	 */
 	if (ops->nr_goto_rules > 0) {
-		struct fib_rule *n;
+		struct fib_rule *n, *r;
 
 		n = list_next_entry(rule, list);
 		if (&n->list == &ops->rules_list || n->pref != rule->pref)
@@ -994,10 +998,12 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 		}
 	}
 
-	call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL, rule, ops,
-				NULL);
-	notify_rule_change(RTM_DELRULE, rule, ops, nlh,
-			   NETLINK_CB(skb).portid);
+	call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL, rule, ops, NULL);
+
+	if (hold_rtnl)
+		rtnl_net_unlock(net);
+
+	notify_rule_change(RTM_DELRULE, rule, ops, nlh, NETLINK_CB(skb).portid);
 	fib_rule_put(rule);
 	flush_route_cache(ops);
 	rules_ops_put(ops);
@@ -1005,6 +1011,8 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	return 0;
 
 errout_free:
+	if (hold_rtnl)
+		rtnl_net_unlock(net);
 	kfree(nlrule);
 errout:
 	rules_ops_put(ops);
@@ -1324,7 +1332,8 @@ static struct pernet_operations fib_rules_net_ops = {
 static const struct rtnl_msg_handler fib_rules_rtnl_msg_handlers[] __initconst = {
 	{.msgtype = RTM_NEWRULE, .doit = fib_nl_newrule,
 	 .flags = RTNL_FLAG_DOIT_PERNET},
-	{.msgtype = RTM_DELRULE, .doit = fib_nl_delrule},
+	{.msgtype = RTM_DELRULE, .doit = fib_nl_delrule,
+	 .flags = RTNL_FLAG_DOIT_PERNET},
 	{.msgtype = RTM_GETRULE, .dumpit = fib_nl_dumprule,
 	 .flags = RTNL_FLAG_DUMP_UNLOCKED},
 };
-- 
2.39.5 (Apple Git-154)