diff options
| -rw-r--r-- | include/linux/netlink.h | 1 | ||||
| -rw-r--r-- | net/netlink/af_netlink.c | 57 |
2 files changed, 46 insertions, 12 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h index b971ddd24090..83d8239f0cce 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -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); diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index c386eaf6ad5b..5681ce3aebca 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -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) |