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[NETLIKN]: Allow removing multicast groups.

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

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Johannes Berg 2007-07-18 15:47:05 -07:00 committed by David S. Miller
parent b4ff4f0419
commit 84659eb529
2 changed files with 46 additions and 12 deletions
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1
include/linux/netlink.h
View File

@ -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);

57
net/netlink/af_netlink.c
View File

@ -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 @@ netlink_kernel_create(int unit, unsigned int groups,
*
* 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)