4 * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/list.h>
25 #include <linux/skbuff.h>
26 #include <net/netlink.h>
27 #include <linux/moduleparam.h>
28 #include <linux/connector.h>
29 #include <linux/slab.h>
30 #include <linux/mutex.h>
31 #include <linux/proc_fs.h>
32 #include <linux/spinlock.h>
36 MODULE_LICENSE("GPL");
37 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
38 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
39 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
41 static struct cn_dev cdev;
43 static int cn_already_initialized;
46 * msg->seq and msg->ack are used to determine message genealogy.
47 * When someone sends message it puts there locally unique sequence
48 * and random acknowledge numbers. Sequence number may be copied into
49 * nlmsghdr->nlmsg_seq too.
51 * Sequence number is incremented with each message to be sent.
53 * If we expect a reply to our message then the sequence number in
54 * received message MUST be the same as in original message, and
55 * acknowledge number MUST be the same + 1.
57 * If we receive a message and its sequence number is not equal to the
58 * one we are expecting then it is a new message.
60 * If we receive a message and its sequence number is the same as one
61 * we are expecting but it's acknowledgement number is not equal to
62 * the acknowledgement number in the original message + 1, then it is
65 * The message is sent to, the portid if given, the group if given, both if
66 * both, or if both are zero then the group is looked up and sent there.
68 int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
71 struct cn_callback_entry *__cbq;
76 struct cn_dev *dev = &cdev;
80 if (portid || __group) {
83 spin_lock_bh(&dev->cbdev->queue_lock);
84 list_for_each_entry(__cbq, &dev->cbdev->queue_list,
86 if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
92 spin_unlock_bh(&dev->cbdev->queue_lock);
98 if (!portid && !netlink_has_listeners(dev->nls, group))
101 size = sizeof(*msg) + msg->len;
103 skb = nlmsg_new(size, gfp_mask);
107 nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0);
113 data = nlmsg_data(nlh);
115 memcpy(data, msg, size);
117 NETLINK_CB(skb).dst_group = group;
120 return netlink_broadcast(dev->nls, skb, portid, group,
122 return netlink_unicast(dev->nls, skb, portid, !(gfp_mask&__GFP_WAIT));
124 EXPORT_SYMBOL_GPL(cn_netlink_send);
127 * Callback helper - queues work and setup destructor for given data.
129 static int cn_call_callback(struct sk_buff *skb)
131 struct cn_callback_entry *i, *cbq = NULL;
132 struct cn_dev *dev = &cdev;
133 struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
134 struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
137 spin_lock_bh(&dev->cbdev->queue_lock);
138 list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
139 if (cn_cb_equal(&i->id.id, &msg->id)) {
140 atomic_inc(&i->refcnt);
145 spin_unlock_bh(&dev->cbdev->queue_lock);
148 cbq->callback(msg, nsp);
150 cn_queue_release_callback(cbq);
158 * Main netlink receiving function.
160 * It checks skb, netlink header and msg sizes, and calls callback helper.
162 static void cn_rx_skb(struct sk_buff *__skb)
164 struct nlmsghdr *nlh;
168 skb = skb_get(__skb);
170 if (skb->len >= NLMSG_HDRLEN) {
171 nlh = nlmsg_hdr(skb);
172 len = nlmsg_len(nlh);
174 if (len < (int)sizeof(struct cn_msg) ||
175 skb->len < nlh->nlmsg_len ||
176 len > CONNECTOR_MAX_MSG_SIZE) {
181 err = cn_call_callback(skb);
188 * Callback add routing - adds callback with given ID and name.
189 * If there is registered callback with the same ID it will not be added.
193 int cn_add_callback(struct cb_id *id, const char *name,
194 void (*callback)(struct cn_msg *,
195 struct netlink_skb_parms *))
198 struct cn_dev *dev = &cdev;
200 if (!cn_already_initialized)
203 err = cn_queue_add_callback(dev->cbdev, name, id, callback);
209 EXPORT_SYMBOL_GPL(cn_add_callback);
212 * Callback remove routing - removes callback
214 * If there is no registered callback with given
215 * ID nothing happens.
217 * May sleep while waiting for reference counter to become zero.
219 void cn_del_callback(struct cb_id *id)
221 struct cn_dev *dev = &cdev;
223 cn_queue_del_callback(dev->cbdev, id);
225 EXPORT_SYMBOL_GPL(cn_del_callback);
227 static int cn_proc_show(struct seq_file *m, void *v)
229 struct cn_queue_dev *dev = cdev.cbdev;
230 struct cn_callback_entry *cbq;
232 seq_printf(m, "Name ID\n");
234 spin_lock_bh(&dev->queue_lock);
236 list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
237 seq_printf(m, "%-15s %u:%u\n",
243 spin_unlock_bh(&dev->queue_lock);
248 static int cn_proc_open(struct inode *inode, struct file *file)
250 return single_open(file, cn_proc_show, NULL);
253 static const struct file_operations cn_file_ops = {
254 .owner = THIS_MODULE,
255 .open = cn_proc_open,
258 .release = single_release
261 static struct cn_dev cdev = {
265 static int cn_init(void)
267 struct cn_dev *dev = &cdev;
268 struct netlink_kernel_cfg cfg = {
269 .groups = CN_NETLINK_USERS + 0xf,
273 dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
277 dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
279 netlink_kernel_release(dev->nls);
283 cn_already_initialized = 1;
285 proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops);
290 static void cn_fini(void)
292 struct cn_dev *dev = &cdev;
294 cn_already_initialized = 0;
296 remove_proc_entry("connector", init_net.proc_net);
298 cn_queue_free_dev(dev->cbdev);
299 netlink_kernel_release(dev->nls);
302 subsys_initcall(cn_init);
303 module_exit(cn_fini);