Commit 32affa55 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

fib: rules: no longer hold RTNL in fib_nl_dumprule() 



- fib rules are already RCU protected, RTNL is not needed
  to get them.

- Fix return value at the end of a dump,
  so that NLMSG_DONE can be appended to current skb,
  saving one recvmsg() system call.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240411133340.1332796-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 195b7fc5

net/core/fib_rules.c

+9 −8
Original line number Diff line number Diff line
@@ -1142,10 +1142,10 @@ static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb) 
	const struct nlmsghdr *nlh = cb->nlh;

	struct net *net = sock_net(skb->sk);

	struct fib_rules_ops *ops;

	int idx = 0, family;

	int err, idx = 0, family;



	if (cb->strict_check) {

		int err = fib_valid_dumprule_req(nlh, cb->extack);

		err = fib_valid_dumprule_req(nlh, cb->extack);



		if (err < 0)

			return err;
@@ -1158,17 +1158,17 @@ static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb) 
		if (ops == NULL)

			return -EAFNOSUPPORT;



		dump_rules(skb, cb, ops);



		return skb->len;

		return dump_rules(skb, cb, ops);

	}



	err = 0;

	rcu_read_lock();

	list_for_each_entry_rcu(ops, &net->rules_ops, list) {

		if (idx < cb->args[0] || !try_module_get(ops->owner))

			goto skip;



		if (dump_rules(skb, cb, ops) < 0)

		err = dump_rules(skb, cb, ops);

		if (err < 0)

			break;



		cb->args[1] = 0;
@@ -1178,7 +1178,7 @@ static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb) 
	rcu_read_unlock();

	cb->args[0] = idx;



	return skb->len;

	return err;

}



static void notify_rule_change(int event, struct fib_rule *rule,
@@ -1293,7 +1293,8 @@ static int __init fib_rules_init(void) 
	int err;

	rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL, 0);

	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule, 0);

	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule,

		      RTNL_FLAG_DUMP_UNLOCKED);



	err = register_pernet_subsys(&fib_rules_net_ops);

	if (err < 0)