Commit 4ce5dc93 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

inet: switch inet_dump_fib() to RCU protection 



No longer hold RTNL while calling inet_dump_fib().

Also change return value for a completed dump:

Returning 0 instead of skb->len allows NLMSG_DONE
to be appended to the skb. User space does not have
to call us again to get a standalone NLMSG_DONE marker.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarDonald Hunter <donald.hunter@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0ac3fa0c

net/ipv4/fib_frontend.c

+18 −19
Original line number Diff line number Diff line
@@ -990,7 +990,7 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
	struct fib_dump_filter filter = {

		.dump_routes = true,

		.dump_exceptions = true,

		.rtnl_held = true,

		.rtnl_held = false,

	};

	const struct nlmsghdr *nlh = cb->nlh;

	struct net *net = sock_net(skb->sk);
@@ -998,12 +998,13 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
	unsigned int e = 0, s_e;

	struct fib_table *tb;

	struct hlist_head *head;

	int dumped = 0, err;

	int dumped = 0, err = 0;



	rcu_read_lock();

	if (cb->strict_check) {

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

		if (err < 0)

			return err;

			goto unlock;

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

		struct rtmsg *rtm = nlmsg_data(nlh);
@@ -1012,29 +1013,28 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 


	/* ipv4 does not use prefix flag */

	if (filter.flags & RTM_F_PREFIX)

		return skb->len;

		goto unlock;



	if (filter.table_id) {

		tb = fib_get_table(net, filter.table_id);

		if (!tb) {

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

				return skb->len;

				goto unlock;



			NL_SET_ERR_MSG(cb->extack, "ipv4: FIB table does not exist");

			return -ENOENT;

			err = -ENOENT;

			goto unlock;

		}



		rcu_read_lock();

		err = fib_table_dump(tb, skb, cb, &filter);

		rcu_read_unlock();

		return skb->len ? : err;

		if (err < 0 && skb->len)

			err = skb->len;

		goto unlock;

	}



	s_h = cb->args[0];

	s_e = cb->args[1];



	rcu_read_lock();



	err = 0;

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

		e = 0;

		head = &net->ipv4.fib_table_hash[h];
@@ -1047,9 +1047,8 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
			err = fib_table_dump(tb, skb, cb, &filter);

			if (err < 0) {

				if (likely(skb->len))

					err = skb->len;

				goto out;



				goto out_err;

			}

			dumped = 1;

next:
@@ -1057,13 +1056,12 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) 
		}

	}

out:

	err = skb->len;

out_err:

	rcu_read_unlock();



	cb->args[1] = e;

	cb->args[0] = h;



unlock:

	rcu_read_unlock();

	return err;

}
@@ -1666,5 +1664,6 @@ void __init ip_fib_init(void) 


	rtnl_register(PF_INET, RTM_NEWROUTE, inet_rtm_newroute, NULL, 0);

	rtnl_register(PF_INET, RTM_DELROUTE, inet_rtm_delroute, NULL, 0);

	rtnl_register(PF_INET, RTM_GETROUTE, NULL, inet_dump_fib, 0);

	rtnl_register(PF_INET, RTM_GETROUTE, NULL, inet_dump_fib,

		      RTNL_FLAG_DUMP_UNLOCKED);

}

net/ipv4/fib_trie.c

+2 −2
Original line number Diff line number Diff line
@@ -2368,7 +2368,7 @@ int fib_table_dump(struct fib_table *tb, struct sk_buff *skb, 
	 * and key == 0 means the dump has wrapped around and we are done.

	 */

	if (count && !key)

		return skb->len;

		return 0;



	while ((l = leaf_walk_rcu(&tp, key)) != NULL) {

		int err;
@@ -2394,7 +2394,7 @@ int fib_table_dump(struct fib_table *tb, struct sk_buff *skb, 
	cb->args[3] = key;

	cb->args[2] = count;



	return skb->len;

	return 0;

}



void __init fib_trie_init(void)