1 /* 2 * connector.c 3 * 4 * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net> 5 * All rights reserved. 6 * 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. 11 * 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. 16 * 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 20 */ 21 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> 33 34 #include <net/sock.h> 35 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); 40 41 static struct cn_dev cdev; 42 43 static int cn_already_initialized; 44 45 /* 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. 50 * 51 * Sequence number is incremented with each message to be sent. 52 * 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. 56 * 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. 59 * 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 63 * a new message. 64 * 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. 67 */ 68 int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, 69 gfp_t gfp_mask) 70 { 71 struct cn_callback_entry *__cbq; 72 unsigned int size; 73 struct sk_buff *skb; 74 struct nlmsghdr *nlh; 75 struct cn_msg *data; 76 struct cn_dev *dev = &cdev; 77 u32 group = 0; 78 int found = 0; 79 80 if (portid || __group) { 81 group = __group; 82 } else { 83 spin_lock_bh(&dev->cbdev->queue_lock); 84 list_for_each_entry(__cbq, &dev->cbdev->queue_list, 85 callback_entry) { 86 if (cn_cb_equal(&__cbq->id.id, &msg->id)) { 87 found = 1; 88 group = __cbq->group; 89 break; 90 } 91 } 92 spin_unlock_bh(&dev->cbdev->queue_lock); 93 94 if (!found) 95 return -ENODEV; 96 } 97 98 if (!portid && !netlink_has_listeners(dev->nls, group)) 99 return -ESRCH; 100 101 size = sizeof(*msg) + msg->len; 102 103 skb = nlmsg_new(size, gfp_mask); 104 if (!skb) 105 return -ENOMEM; 106 107 nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0); 108 if (!nlh) { 109 kfree_skb(skb); 110 return -EMSGSIZE; 111 } 112 113 data = nlmsg_data(nlh); 114 115 memcpy(data, msg, size); 116 117 NETLINK_CB(skb).dst_group = group; 118 119 if (group) 120 return netlink_broadcast(dev->nls, skb, portid, group, 121 gfp_mask); 122 return netlink_unicast(dev->nls, skb, portid, !(gfp_mask&__GFP_WAIT)); 123 } 124 EXPORT_SYMBOL_GPL(cn_netlink_send); 125 126 /* 127 * Callback helper - queues work and setup destructor for given data. 128 */ 129 static int cn_call_callback(struct sk_buff *skb) 130 { 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); 135 int err = -ENODEV; 136 137 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); 141 cbq = i; 142 break; 143 } 144 } 145 spin_unlock_bh(&dev->cbdev->queue_lock); 146 147 if (cbq != NULL) { 148 cbq->callback(msg, nsp); 149 kfree_skb(skb); 150 cn_queue_release_callback(cbq); 151 err = 0; 152 } 153 154 return err; 155 } 156 157 /* 158 * Main netlink receiving function. 159 * 160 * It checks skb, netlink header and msg sizes, and calls callback helper. 161 */ 162 static void cn_rx_skb(struct sk_buff *__skb) 163 { 164 struct nlmsghdr *nlh; 165 struct sk_buff *skb; 166 int len, err; 167 168 skb = skb_get(__skb); 169 170 if (skb->len >= NLMSG_HDRLEN) { 171 nlh = nlmsg_hdr(skb); 172 len = nlmsg_len(nlh); 173 174 if (len < (int)sizeof(struct cn_msg) || 175 skb->len < nlh->nlmsg_len || 176 len > CONNECTOR_MAX_MSG_SIZE) { 177 kfree_skb(skb); 178 return; 179 } 180 181 err = cn_call_callback(skb); 182 if (err < 0) 183 kfree_skb(skb); 184 } 185 } 186 187 /* 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. 190 * 191 * May sleep. 192 */ 193 int cn_add_callback(struct cb_id *id, const char *name, 194 void (*callback)(struct cn_msg *, 195 struct netlink_skb_parms *)) 196 { 197 int err; 198 struct cn_dev *dev = &cdev; 199 200 if (!cn_already_initialized) 201 return -EAGAIN; 202 203 err = cn_queue_add_callback(dev->cbdev, name, id, callback); 204 if (err) 205 return err; 206 207 return 0; 208 } 209 EXPORT_SYMBOL_GPL(cn_add_callback); 210 211 /* 212 * Callback remove routing - removes callback 213 * with given ID. 214 * If there is no registered callback with given 215 * ID nothing happens. 216 * 217 * May sleep while waiting for reference counter to become zero. 218 */ 219 void cn_del_callback(struct cb_id *id) 220 { 221 struct cn_dev *dev = &cdev; 222 223 cn_queue_del_callback(dev->cbdev, id); 224 } 225 EXPORT_SYMBOL_GPL(cn_del_callback); 226 227 static int cn_proc_show(struct seq_file *m, void *v) 228 { 229 struct cn_queue_dev *dev = cdev.cbdev; 230 struct cn_callback_entry *cbq; 231 232 seq_printf(m, "Name ID\n"); 233 234 spin_lock_bh(&dev->queue_lock); 235 236 list_for_each_entry(cbq, &dev->queue_list, callback_entry) { 237 seq_printf(m, "%-15s %u:%u\n", 238 cbq->id.name, 239 cbq->id.id.idx, 240 cbq->id.id.val); 241 } 242 243 spin_unlock_bh(&dev->queue_lock); 244 245 return 0; 246 } 247 248 static int cn_proc_open(struct inode *inode, struct file *file) 249 { 250 return single_open(file, cn_proc_show, NULL); 251 } 252 253 static const struct file_operations cn_file_ops = { 254 .owner = THIS_MODULE, 255 .open = cn_proc_open, 256 .read = seq_read, 257 .llseek = seq_lseek, 258 .release = single_release 259 }; 260 261 static struct cn_dev cdev = { 262 .input = cn_rx_skb, 263 }; 264 265 static int cn_init(void) 266 { 267 struct cn_dev *dev = &cdev; 268 struct netlink_kernel_cfg cfg = { 269 .groups = CN_NETLINK_USERS + 0xf, 270 .input = dev->input, 271 }; 272 273 dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg); 274 if (!dev->nls) 275 return -EIO; 276 277 dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); 278 if (!dev->cbdev) { 279 netlink_kernel_release(dev->nls); 280 return -EINVAL; 281 } 282 283 cn_already_initialized = 1; 284 285 proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops); 286 287 return 0; 288 } 289 290 static void cn_fini(void) 291 { 292 struct cn_dev *dev = &cdev; 293 294 cn_already_initialized = 0; 295 296 remove_proc_entry("connector", init_net.proc_net); 297 298 cn_queue_free_dev(dev->cbdev); 299 netlink_kernel_release(dev->nls); 300 } 301 302 subsys_initcall(cn_init); 303 module_exit(cn_fini); 304