[NETLINK]: Add properly module refcounting for kernel netlink sockets.
- Remove bogus code for compiling netlink as module
- Add module refcounting support for modules implementing a netlink
protocol
- Add support for autoloading modules that implement a netlink protocol
as soon as someone opens a socket for that protocol
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index ff774a0..5d487cd 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -13,7 +13,12 @@
* added netlink_proto_exit
* Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
* use nlk_sk, as sk->protinfo is on a diet 8)
- *
+ * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
+ * - inc module use count of module that owns
+ * the kernel socket in case userspace opens
+ * socket of same protocol
+ * - remove all module support, since netlink is
+ * mandatory if CONFIG_NET=y these days
*/
#include <linux/config.h>
@@ -92,6 +97,7 @@
struct nl_pid_hash hash;
struct hlist_head mc_list;
unsigned int nl_nonroot;
+ struct proto_ops *p_ops;
};
static struct netlink_table *nl_table;
@@ -341,7 +347,21 @@
if (protocol<0 || protocol >= MAX_LINKS)
return -EPROTONOSUPPORT;
- sock->ops = &netlink_ops;
+ netlink_table_grab();
+ if (!nl_table[protocol].hash.entries) {
+#ifdef CONFIG_KMOD
+ /* We do 'best effort'. If we find a matching module,
+ * it is loaded. If not, we don't return an error to
+ * allow pure userspace<->userspace communication. -HW
+ */
+ netlink_table_ungrab();
+ request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
+ netlink_table_grab();
+#endif
+ }
+ netlink_table_ungrab();
+
+ sock->ops = nl_table[protocol].p_ops;
sk = sk_alloc(PF_NETLINK, GFP_KERNEL, &netlink_proto, 1);
if (!sk)
@@ -394,6 +414,22 @@
};
notifier_call_chain(&netlink_chain, NETLINK_URELEASE, &n);
}
+
+ /* When this is a kernel socket, we need to remove the owner pointer,
+ * since we don't know whether the module will be dying at any given
+ * point - HW
+ */
+ if (!nlk->pid) {
+ struct proto_ops *p_tmp;
+
+ netlink_table_grab();
+ p_tmp = nl_table[sk->sk_protocol].p_ops;
+ if (p_tmp != &netlink_ops) {
+ nl_table[sk->sk_protocol].p_ops = &netlink_ops;
+ kfree(p_tmp);
+ }
+ netlink_table_ungrab();
+ }
sock_put(sk);
return 0;
@@ -1023,8 +1059,9 @@
*/
struct sock *
-netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len))
+netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len), struct module *module)
{
+ struct proto_ops *p_ops;
struct socket *sock;
struct sock *sk;
@@ -1034,22 +1071,63 @@
if (unit<0 || unit>=MAX_LINKS)
return NULL;
+ /* Do a quick check, to make us not go down to netlink_insert()
+ * if protocol already has kernel socket.
+ */
+ sk = netlink_lookup(unit, 0);
+ if (unlikely(sk)) {
+ sock_put(sk);
+ return NULL;
+ }
+
if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
return NULL;
+ sk = NULL;
+ if (module) {
+ /* Every registering protocol implemented in a module needs
+ * it's own p_ops, since the socket code cannot deal with
+ * module refcounting otherwise. -HW
+ */
+ p_ops = kmalloc(sizeof(*p_ops), GFP_KERNEL);
+ if (!p_ops)
+ goto out_sock_release;
+
+ memcpy(p_ops, &netlink_ops, sizeof(*p_ops));
+ p_ops->owner = module;
+ } else
+ p_ops = &netlink_ops;
+
+ netlink_table_grab();
+ nl_table[unit].p_ops = p_ops;
+ netlink_table_ungrab();
+
if (netlink_create(sock, unit) < 0) {
- sock_release(sock);
- return NULL;
+ sk = NULL;
+ goto out_kfree_p_ops;
}
+
sk = sock->sk;
sk->sk_data_ready = netlink_data_ready;
if (input)
nlk_sk(sk)->data_ready = input;
if (netlink_insert(sk, 0)) {
- sock_release(sock);
- return NULL;
+ sk = NULL;
+ goto out_kfree_p_ops;
}
+
+ return sk;
+
+out_kfree_p_ops:
+ netlink_table_grab();
+ if (nl_table[unit].p_ops != &netlink_ops) {
+ kfree(nl_table[unit].p_ops);
+ nl_table[unit].p_ops = &netlink_ops;
+ }
+ netlink_table_ungrab();
+out_sock_release:
+ sock_release(sock);
return sk;
}
@@ -1413,6 +1491,8 @@
for (i = 0; i < MAX_LINKS; i++) {
struct nl_pid_hash *hash = &nl_table[i].hash;
+ nl_table[i].p_ops = &netlink_ops;
+
hash->table = nl_pid_hash_alloc(1 * sizeof(*hash->table));
if (!hash->table) {
while (i-- > 0)
@@ -1438,21 +1518,7 @@
return err;
}
-static void __exit netlink_proto_exit(void)
-{
- sock_unregister(PF_NETLINK);
- proc_net_remove("netlink");
- kfree(nl_table);
- nl_table = NULL;
- proto_unregister(&netlink_proto);
-}
-
core_initcall(netlink_proto_init);
-module_exit(netlink_proto_exit);
-
-MODULE_LICENSE("GPL");
-
-MODULE_ALIAS_NETPROTO(PF_NETLINK);
EXPORT_SYMBOL(netlink_ack);
EXPORT_SYMBOL(netlink_broadcast);