Commit 5fc68320 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

ipv6: remove RTNL protection from inet6_dump_fib() 



No longer hold RTNL while calling inet6_dump_fib().

Also change return value for a completed 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/20240329183053.644630-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent edaa34e6

net/ipv6/ip6_fib.c

+26 −25
Original line number Diff line number Diff line
@@ -623,23 +623,22 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
	struct rt6_rtnl_dump_arg arg = {

		.filter.dump_exceptions = true,

		.filter.dump_routes = true,

		.filter.rtnl_held = true,

		.filter.rtnl_held = false,

	};

	const struct nlmsghdr *nlh = cb->nlh;

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

	unsigned int h, s_h;

	unsigned int e = 0, s_e;

	struct hlist_head *head;

	struct fib6_walker *w;

	struct fib6_table *tb;

	struct hlist_head *head;

	int res = 0;

	unsigned int h, s_h;

	int err = 0;



	rcu_read_lock();

	if (cb->strict_check) {

		int err;



		err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb);

		if (err < 0)

			return err;

			goto unlock;

	} else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {

		struct rtmsg *rtm = nlmsg_data(nlh);
@@ -660,8 +659,10 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
		 * 2. allocate and initialize walker.

		 */

		w = kzalloc(sizeof(*w), GFP_ATOMIC);

		if (!w)

			return -ENOMEM;

		if (!w) {

			err = -ENOMEM;

			goto unlock;

		}

		w->func = fib6_dump_node;

		cb->args[2] = (long)w;

	}
@@ -675,46 +676,46 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
		tb = fib6_get_table(net, arg.filter.table_id);

		if (!tb) {

			if (rtnl_msg_family(cb->nlh) != PF_INET6)

				goto out;

				goto unlock;



			NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist");

			return -ENOENT;

			err = -ENOENT;

			goto unlock;

		}



		if (!cb->args[0]) {

			res = fib6_dump_table(tb, skb, cb);

			if (!res)

			err = fib6_dump_table(tb, skb, cb);

			if (!err)

				cb->args[0] = 1;

		}

		goto out;

		goto unlock;

	}



	s_h = cb->args[0];

	s_e = cb->args[1];



	rcu_read_lock();

	for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {

		e = 0;

		head = &net->ipv6.fib_table_hash[h];

		hlist_for_each_entry_rcu(tb, head, tb6_hlist) {

			if (e < s_e)

				goto next;

			res = fib6_dump_table(tb, skb, cb);

			if (res != 0)

				goto out_unlock;

			err = fib6_dump_table(tb, skb, cb);

			if (err != 0)

				goto out;

next:

			e++;

		}

	}

out_unlock:

	rcu_read_unlock();

out:

	cb->args[1] = e;

	cb->args[0] = h;

out:

	res = res < 0 ? res : skb->len;

	if (res <= 0)



unlock:

	rcu_read_unlock();

	if (err <= 0)

		fib6_dump_end(cb);

	return res;

	return err;

}



void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val)
@@ -2506,7 +2507,7 @@ int __init fib6_init(void) 
		goto out_kmem_cache_create;



	ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL,

				   inet6_dump_fib, 0);

				   inet6_dump_fib, RTNL_FLAG_DUMP_UNLOCKED);

	if (ret)

		goto out_unregister_subsys;