From 4fdb3bb723db469717c6d38fda667d8b0fa86ebd Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Tue, 9 Aug 2005 19:40:55 -0700 Subject: [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 Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 108 ++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 87 insertions(+), 21 deletions(-) (limited to 'net/netlink') diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index ff774a06c89d..5d487cd69c8c 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 * use nlk_sk, as sk->protinfo is on a diet 8) - * + * Fri Jul 22 19:51:12 MEST 2005 Harald Welte + * - 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 @@ -92,6 +97,7 @@ struct netlink_table { 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 @@ static int netlink_create(struct socket *sock, int protocol) 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 @@ static int netlink_release(struct socket *sock) }; 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 @@ static void netlink_data_ready(struct sock *sk, int len) */ 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 @@ netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len)) 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 @@ enomem: 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 @@ out: 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); -- cgit v1.2.3