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Commit 84659eb5 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller
Browse files

[NETLIKN]: Allow removing multicast groups. 



Allow kicking listeners out of a multicast group when necessary
(for example if that group is going to be removed.)

Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Acked-by: default avatarPatrick McHardy <kaber@trash.net>
Acked-by: default avatarJamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b4ff4f04

include/linux/netlink.h

+1 −0
Original line number Diff line number Diff line
@@ -162,6 +162,7 @@ extern struct sock *netlink_kernel_create(int unit, unsigned int groups, 
					  struct mutex *cb_mutex,

					  struct module *module);

extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);

extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);

extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);

extern int netlink_has_listeners(struct sock *sk, unsigned int group);

extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock);

net/netlink/af_netlink.c

+45 −12
Original line number Diff line number Diff line
@@ -1027,6 +1027,23 @@ void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code) 
	read_unlock(&nl_table_lock);

}



/* must be called with netlink table grabbed */

static void netlink_update_socket_mc(struct netlink_sock *nlk,

				     unsigned int group,

				     int is_new)

{

	int old, new = !!is_new, subscriptions;



	old = test_bit(group - 1, nlk->groups);

	subscriptions = nlk->subscriptions - old + new;

	if (new)

		__set_bit(group - 1, nlk->groups);

	else

		__clear_bit(group - 1, nlk->groups);

	netlink_update_subscriptions(&nlk->sk, subscriptions);

	netlink_update_listeners(&nlk->sk);

}



static int netlink_setsockopt(struct socket *sock, int level, int optname,

			      char __user *optval, int optlen)

{
@@ -1052,9 +1069,6 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname, 
		break;

	case NETLINK_ADD_MEMBERSHIP:

	case NETLINK_DROP_MEMBERSHIP: {

		unsigned int subscriptions;

		int old, new = optname == NETLINK_ADD_MEMBERSHIP ? 1 : 0;



		if (!netlink_capable(sock, NL_NONROOT_RECV))

			return -EPERM;

		err = netlink_realloc_groups(sk);
@@ -1063,14 +1077,8 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname, 
		if (!val || val - 1 >= nlk->ngroups)

			return -EINVAL;

		netlink_table_grab();

		old = test_bit(val - 1, nlk->groups);

		subscriptions = nlk->subscriptions - old + new;

		if (new)

			__set_bit(val - 1, nlk->groups);

		else

			__clear_bit(val - 1, nlk->groups);

		netlink_update_subscriptions(sk, subscriptions);

		netlink_update_listeners(sk);

		netlink_update_socket_mc(nlk, val,

					 optname == NETLINK_ADD_MEMBERSHIP);

		netlink_table_ungrab();

		err = 0;

		break;
@@ -1351,7 +1359,9 @@ out_sock_release: 
 *

 * This changes the number of multicast groups that are available

 * on a certain netlink family. Note that it is not possible to

 * change the number of groups to below 32.

 * change the number of groups to below 32. Also note that it does

 * not implicitly call netlink_clear_multicast_users() when the

 * number of groups is reduced.

 *

 * @sk: The kernel netlink socket, as returned by netlink_kernel_create().

 * @groups: The new number of groups.
@@ -1386,6 +1396,29 @@ int netlink_change_ngroups(struct sock *sk, unsigned int groups) 
}

EXPORT_SYMBOL(netlink_change_ngroups);



/**

 * netlink_clear_multicast_users - kick off multicast listeners

 *

 * This function removes all listeners from the given group.

 * @ksk: The kernel netlink socket, as returned by

 *	netlink_kernel_create().

 * @group: The multicast group to clear.

 */

void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)

{

	struct sock *sk;

	struct hlist_node *node;

	struct netlink_table *tbl = &nl_table[ksk->sk_protocol];



	netlink_table_grab();



	sk_for_each_bound(sk, node, &tbl->mc_list)

		netlink_update_socket_mc(nlk_sk(sk), group, 0);



	netlink_table_ungrab();

}

EXPORT_SYMBOL(netlink_clear_multicast_users);



void netlink_set_nonroot(int protocol, unsigned int flags)

{

	if ((unsigned int)protocol < MAX_LINKS)