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 * Sends mult (multiple) cn_msg at a time. 47 * 48 * msg->seq and msg->ack are used to determine message genealogy. 49 * When someone sends message it puts there locally unique sequence 50 * and random acknowledge numbers. Sequence number may be copied into 51 * nlmsghdr->nlmsg_seq too. 52 * 53 * Sequence number is incremented with each message to be sent. 54 * 55 * If we expect a reply to our message then the sequence number in 56 * received message MUST be the same as in original message, and 57 * acknowledge number MUST be the same + 1. 58 * 59 * If we receive a message and its sequence number is not equal to the 60 * one we are expecting then it is a new message. 61 * 62 * If we receive a message and its sequence number is the same as one 63 * we are expecting but it's acknowledgement number is not equal to 64 * the acknowledgement number in the original message + 1, then it is 65 * a new message. 66 * 67 * If msg->len != len, then additional cn_msg messages are expected following 68 * the first msg. 69 * 70 * The message is sent to, the portid if given, the group if given, both if 71 * both, or if both are zero then the group is looked up and sent there. 72 */ 73 int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group, 74 gfp_t gfp_mask) 75 { 76 struct cn_callback_entry *__cbq; 77 unsigned int size; 78 struct sk_buff *skb; 79 struct nlmsghdr *nlh; 80 struct cn_msg *data; 81 struct cn_dev *dev = &cdev; 82 u32 group = 0; 83 int found = 0; 84 85 if (portid || __group) { 86 group = __group; 87 } else { 88 spin_lock_bh(&dev->cbdev->queue_lock); 89 list_for_each_entry(__cbq, &dev->cbdev->queue_list, 90 callback_entry) { 91 if (cn_cb_equal(&__cbq->id.id, &msg->id)) { 92 found = 1; 93 group = __cbq->group; 94 break; 95 } 96 } 97 spin_unlock_bh(&dev->cbdev->queue_lock); 98 99 if (!found) 100 return -ENODEV; 101 } 102 103 if (!portid && !netlink_has_listeners(dev->nls, group)) 104 return -ESRCH; 105 106 size = sizeof(*msg) + len; 107 108 skb = nlmsg_new(size, gfp_mask); 109 if (!skb) 110 return -ENOMEM; 111 112 nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0); 113 if (!nlh) { 114 kfree_skb(skb); 115 return -EMSGSIZE; 116 } 117 118 data = nlmsg_data(nlh); 119 120 memcpy(data, msg, size); 121 122 NETLINK_CB(skb).dst_group = group; 123 124 if (group) 125 return netlink_broadcast(dev->nls, skb, portid, group, 126 gfp_mask); 127 return netlink_unicast(dev->nls, skb, portid, !(gfp_mask&__GFP_WAIT)); 128 } 129 EXPORT_SYMBOL_GPL(cn_netlink_send_mult); 130 131 /* same as cn_netlink_send_mult except msg->len is used for len */ 132 int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, 133 gfp_t gfp_mask) 134 { 135 return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask); 136 } 137 EXPORT_SYMBOL_GPL(cn_netlink_send); 138 139 /* 140 * Callback helper - queues work and setup destructor for given data. 141 */ 142 static int cn_call_callback(struct sk_buff *skb) 143 { 144 struct nlmsghdr *nlh; 145 struct cn_callback_entry *i, *cbq = NULL; 146 struct cn_dev *dev = &cdev; 147 struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb)); 148 struct netlink_skb_parms *nsp = &NETLINK_CB(skb); 149 int err = -ENODEV; 150 151 /* verify msg->len is within skb */ 152 nlh = nlmsg_hdr(skb); 153 if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len) 154 return -EINVAL; 155 156 spin_lock_bh(&dev->cbdev->queue_lock); 157 list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) { 158 if (cn_cb_equal(&i->id.id, &msg->id)) { 159 atomic_inc(&i->refcnt); 160 cbq = i; 161 break; 162 } 163 } 164 spin_unlock_bh(&dev->cbdev->queue_lock); 165 166 if (cbq != NULL) { 167 cbq->callback(msg, nsp); 168 kfree_skb(skb); 169 cn_queue_release_callback(cbq); 170 err = 0; 171 } 172 173 return err; 174 } 175 176 /* 177 * Main netlink receiving function. 178 * 179 * It checks skb, netlink header and msg sizes, and calls callback helper. 180 */ 181 static void cn_rx_skb(struct sk_buff *__skb) 182 { 183 struct nlmsghdr *nlh; 184 struct sk_buff *skb; 185 int len, err; 186 187 skb = skb_get(__skb); 188 189 if (skb->len >= NLMSG_HDRLEN) { 190 nlh = nlmsg_hdr(skb); 191 len = nlmsg_len(nlh); 192 193 if (len < (int)sizeof(struct cn_msg) || 194 skb->len < nlh->nlmsg_len || 195 len > CONNECTOR_MAX_MSG_SIZE) { 196 kfree_skb(skb); 197 return; 198 } 199 200 err = cn_call_callback(skb); 201 if (err < 0) 202 kfree_skb(skb); 203 } 204 } 205 206 /* 207 * Callback add routing - adds callback with given ID and name. 208 * If there is registered callback with the same ID it will not be added. 209 * 210 * May sleep. 211 */ 212 int cn_add_callback(struct cb_id *id, const char *name, 213 void (*callback)(struct cn_msg *, 214 struct netlink_skb_parms *)) 215 { 216 int err; 217 struct cn_dev *dev = &cdev; 218 219 if (!cn_already_initialized) 220 return -EAGAIN; 221 222 err = cn_queue_add_callback(dev->cbdev, name, id, callback); 223 if (err) 224 return err; 225 226 return 0; 227 } 228 EXPORT_SYMBOL_GPL(cn_add_callback); 229 230 /* 231 * Callback remove routing - removes callback 232 * with given ID. 233 * If there is no registered callback with given 234 * ID nothing happens. 235 * 236 * May sleep while waiting for reference counter to become zero. 237 */ 238 void cn_del_callback(struct cb_id *id) 239 { 240 struct cn_dev *dev = &cdev; 241 242 cn_queue_del_callback(dev->cbdev, id); 243 } 244 EXPORT_SYMBOL_GPL(cn_del_callback); 245 246 static int cn_proc_show(struct seq_file *m, void *v) 247 { 248 struct cn_queue_dev *dev = cdev.cbdev; 249 struct cn_callback_entry *cbq; 250 251 seq_printf(m, "Name ID\n"); 252 253 spin_lock_bh(&dev->queue_lock); 254 255 list_for_each_entry(cbq, &dev->queue_list, callback_entry) { 256 seq_printf(m, "%-15s %u:%u\n", 257 cbq->id.name, 258 cbq->id.id.idx, 259 cbq->id.id.val); 260 } 261 262 spin_unlock_bh(&dev->queue_lock); 263 264 return 0; 265 } 266 267 static int cn_proc_open(struct inode *inode, struct file *file) 268 { 269 return single_open(file, cn_proc_show, NULL); 270 } 271 272 static const struct file_operations cn_file_ops = { 273 .owner = THIS_MODULE, 274 .open = cn_proc_open, 275 .read = seq_read, 276 .llseek = seq_lseek, 277 .release = single_release 278 }; 279 280 static struct cn_dev cdev = { 281 .input = cn_rx_skb, 282 }; 283 284 static int cn_init(void) 285 { 286 struct cn_dev *dev = &cdev; 287 struct netlink_kernel_cfg cfg = { 288 .groups = CN_NETLINK_USERS + 0xf, 289 .input = dev->input, 290 }; 291 292 dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg); 293 if (!dev->nls) 294 return -EIO; 295 296 dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); 297 if (!dev->cbdev) { 298 netlink_kernel_release(dev->nls); 299 return -EINVAL; 300 } 301 302 cn_already_initialized = 1; 303 304 proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops); 305 306 return 0; 307 } 308 309 static void cn_fini(void) 310 { 311 struct cn_dev *dev = &cdev; 312 313 cn_already_initialized = 0; 314 315 remove_proc_entry("connector", init_net.proc_net); 316 317 cn_queue_free_dev(dev->cbdev); 318 netlink_kernel_release(dev->nls); 319 } 320 321 subsys_initcall(cn_init); 322 module_exit(cn_fini); 323