[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/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index b5a5e04..8809788 100644 (file)
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -88,7 +88,7 @@ static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
 
        dev->groups = 23;
        dev->seq = 1;
-       dev->nls = netlink_kernel_create(NETLINK_W1, NULL);
+       dev->nls = netlink_kernel_create(NETLINK_W1, NULL, THIS_MODULE);
        if (!dev->nls) {
                printk(KERN_ERR "Failed to create new netlink socket(%u) for w1 master %s.\n",
                        NETLINK_NFLOG, dev->dev.bus_id);
@@ -225,3 +225,5 @@ void w1_remove_master_device(struct w1_bus_master *bm)
 
 EXPORT_SYMBOL(w1_add_master_device);
 EXPORT_SYMBOL(w1_remove_master_device);
+
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_W1);

diff --git a/include/linux/net.h b/include/linux/net.h
index 20cb226..3990661 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -282,5 +282,8 @@ static struct proto_ops name##_ops = {                      \
 #define MODULE_ALIAS_NETPROTO(proto) \
        MODULE_ALIAS("net-pf-" __stringify(proto))
 
+#define MODULE_ALIAS_NET_PF_PROTO(pf, proto) \
+       MODULE_ALIAS("net-pf-" __stringify(pf) "-proto-" __stringify(proto))
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_NET_H */

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 6552b71..1c50fea 100644 (file)
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -117,7 +117,7 @@ struct netlink_skb_parms
 #define NETLINK_CREDS(skb)     (&NETLINK_CB((skb)).creds)
 
 
-extern struct sock *netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len));
+extern struct sock *netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len), struct module *module);
 extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock);
 extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 pid,

diff --git a/kernel/audit.c b/kernel/audit.c
index ef35166..ed40195 100644 (file)
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -514,7 +514,8 @@ static int __init audit_init(void)
 {
        printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
               audit_default ? "enabled" : "disabled");
-       audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive);
+       audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive,
+                                          THIS_MODULE);
        if (!audit_sock)
                audit_panic("cannot initialize netlink socket");
 

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 8e49d21..88f4d74 100644 (file)
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -153,7 +153,8 @@ EXPORT_SYMBOL_GPL(kobject_uevent_atomic);
 
 static int __init kobject_uevent_init(void)
 {
-       uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, NULL);
+       uevent_sock = netlink_kernel_create(NETLINK_KOBJECT_UEVENT, NULL,
+                                           THIS_MODULE);
 
        if (!uevent_sock) {
                printk(KERN_ERR

diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c
index 01af4fc..561d75c 100644 (file)
--- a/net/bridge/netfilter/ebt_ulog.c
+++ b/net/bridge/netfilter/ebt_ulog.c
@@ -258,7 +258,7 @@ static int __init init(void)
                spin_lock_init(&ulog_buffers[i].lock);
        }
 
-       ebtulognl = netlink_kernel_create(NETLINK_NFLOG, NULL);
+       ebtulognl = netlink_kernel_create(NETLINK_NFLOG, NULL, THIS_MODULE);
        if (!ebtulognl)
                ret = -ENOMEM;
        else if ((ret = ebt_register_watcher(&ulog)))

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 4b1bb30..9b3c61f 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -708,7 +708,7 @@ void __init rtnetlink_init(void)
        if (!rta_buf)
                panic("rtnetlink_init: cannot allocate rta_buf\n");
 
-       rtnl = netlink_kernel_create(NETLINK_ROUTE, rtnetlink_rcv);
+       rtnl = netlink_kernel_create(NETLINK_ROUTE, rtnetlink_rcv, THIS_MODULE);
        if (rtnl == NULL)
                panic("rtnetlink_init: cannot initialize rtnetlink\n");
        netlink_set_nonroot(NETLINK_ROUTE, NL_NONROOT_RECV);

diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c
index 284a999..3068fdd 100644 (file)
--- a/net/decnet/netfilter/dn_rtmsg.c
+++ b/net/decnet/netfilter/dn_rtmsg.c
@@ -138,7 +138,8 @@ static int __init init(void)
 {
        int rv = 0;
 
-       dnrmg = netlink_kernel_create(NETLINK_DNRTMSG, dnrmg_receive_user_sk);
+       dnrmg = netlink_kernel_create(NETLINK_DNRTMSG, dnrmg_receive_user_sk,
+                                     THIS_MODULE);
        if (dnrmg == NULL) {
                printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
                return -ENOMEM;
@@ -162,6 +163,7 @@ static void __exit fini(void)
 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 
 module_init(init);
 module_exit(fini);

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index e572208..b5e2f15 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -567,7 +567,7 @@ static void nl_fib_input(struct sock *sk, int len)
 
 static void nl_fib_lookup_init(void)
 {
-      netlink_kernel_create(NETLINK_FIB_LOOKUP, nl_fib_input);
+      netlink_kernel_create(NETLINK_FIB_LOOKUP, nl_fib_input, THIS_MODULE);
 }
 
 static void fib_disable_ip(struct net_device *dev, int force)

diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index ae975ac..b237f7f 100644 (file)
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -692,7 +692,8 @@ init_or_cleanup(int init)
                goto cleanup;
 
        netlink_register_notifier(&ipq_nl_notifier);
-       ipqnl = netlink_kernel_create(NETLINK_FIREWALL, ipq_rcv_sk);
+       ipqnl = netlink_kernel_create(NETLINK_FIREWALL, ipq_rcv_sk,
+                                     THIS_MODULE);
        if (ipqnl == NULL) {
                printk(KERN_ERR "ip_queue: failed to create netlink socket\n");
                goto cleanup_netlink_notifier;

diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c
index 52a0076..4ea8371 100644 (file)
--- a/net/ipv4/netfilter/ipt_ULOG.c
+++ b/net/ipv4/netfilter/ipt_ULOG.c
@@ -62,6 +62,7 @@
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
 MODULE_DESCRIPTION("iptables userspace logging module");
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
 
 #define ULOG_NL_EVENT          111             /* Harald's favorite number */
 #define ULOG_MAXNLGROUPS       32              /* numer of nlgroups */
@@ -372,7 +373,7 @@ static int __init init(void)
                ulog_buffers[i].timer.data = i;
        }
 
-       nflognl = netlink_kernel_create(NETLINK_NFLOG, NULL);
+       nflognl = netlink_kernel_create(NETLINK_NFLOG, NULL, THIS_MODULE);
        if (!nflognl)
                return -ENOMEM;
 

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index f66945c..f79bd11 100644 (file)
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -774,7 +774,8 @@ static void tcpdiag_rcv(struct sock *sk, int len)
 
 static int __init tcpdiag_init(void)
 {
-       tcpnl = netlink_kernel_create(NETLINK_TCPDIAG, tcpdiag_rcv);
+       tcpnl = netlink_kernel_create(NETLINK_TCPDIAG, tcpdiag_rcv,
+                                     THIS_MODULE);
        if (tcpnl == NULL)
                return -ENOMEM;
        return 0;

diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c
index 7130603..1c3d247 100644 (file)
--- a/net/ipv6/netfilter/ip6_queue.c
+++ b/net/ipv6/netfilter/ip6_queue.c
@@ -685,7 +685,7 @@ init_or_cleanup(int init)
                goto cleanup;
 
        netlink_register_notifier(&ipq_nl_notifier);
-       ipqnl = netlink_kernel_create(NETLINK_IP6_FW, ipq_rcv_sk);
+       ipqnl = netlink_kernel_create(NETLINK_IP6_FW, ipq_rcv_sk, THIS_MODULE);
        if (ipqnl == NULL) {
                printk(KERN_ERR "ip6_queue: failed to create netlink socket\n");
                goto cleanup_netlink_notifier;

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index b0ed579..6210ca4 100644 (file)
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -38,6 +38,8 @@
 #include <linux/netfilter/nfnetlink.h>
 
 MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
 
 static char __initdata nfversion[] = "0.30";
 
@@ -324,7 +326,8 @@ int __init nfnetlink_init(void)
 {
        printk("Netfilter messages via NETLINK v%s.\n", nfversion);
 
-       nfnl = netlink_kernel_create(NETLINK_NETFILTER, nfnetlink_rcv);
+       nfnl = netlink_kernel_create(NETLINK_NETFILTER, nfnetlink_rcv,
+                                    THIS_MODULE);
        if (!nfnl) {
                printk(KERN_ERR "cannot initialize nfnetlink!\n");
                return -1;

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index ff774a0..5d487cd 100644 (file)
--- 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 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);

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 8da3e25..33ceeea 100644 (file)
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1519,7 +1519,8 @@ static int __init xfrm_user_init(void)
 {
        printk(KERN_INFO "Initializing IPsec netlink socket\n");
 
-       xfrm_nl = netlink_kernel_create(NETLINK_XFRM, xfrm_netlink_rcv);
+       xfrm_nl = netlink_kernel_create(NETLINK_XFRM, xfrm_netlink_rcv,
+                                       THIS_MODULE);
        if (xfrm_nl == NULL)
                return -ENOMEM;
 
@@ -1537,3 +1538,4 @@ static void __exit xfrm_user_exit(void)
 module_init(xfrm_user_init);
 module_exit(xfrm_user_exit);
 MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_XFRM);

diff --git a/security/selinux/netlink.c b/security/selinux/netlink.c
index 18d08ac..341dbe2 100644 (file)
--- a/security/selinux/netlink.c
+++ b/security/selinux/netlink.c
@@ -103,7 +103,7 @@ void selnl_notify_policyload(u32 seqno)
 
 static int __init selnl_init(void)
 {
-       selnl = netlink_kernel_create(NETLINK_SELINUX, NULL);
+       selnl = netlink_kernel_create(NETLINK_SELINUX, NULL, THIS_MODULE);
        if (selnl == NULL)
                panic("SELinux:  Cannot create netlink socket.");
        netlink_set_nonroot(NETLINK_SELINUX, NL_NONROOT_RECV);