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, 128 !gfpflags_allow_blocking(gfp_mask)); 129 } 130 EXPORT_SYMBOL_GPL(cn_netlink_send_mult); 131 132 /* same as cn_netlink_send_mult except msg->len is used for len */ 133 int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, 134 gfp_t gfp_mask) 135 { 136 return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask); 137 } 138 EXPORT_SYMBOL_GPL(cn_netlink_send); 139 140 /* 141 * Callback helper - queues work and setup destructor for given data. 142 */ 143 static int cn_call_callback(struct sk_buff *skb) 144 { 145 struct nlmsghdr *nlh; 146 struct cn_callback_entry *i, *cbq = NULL; 147 struct cn_dev *dev = &cdev; 148 struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb)); 149 struct netlink_skb_parms *nsp = &NETLINK_CB(skb); 150 int err = -ENODEV; 151 152 /* verify msg->len is within skb */ 153 nlh = nlmsg_hdr(skb); 154 if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len) 155 return -EINVAL; 156 157 spin_lock_bh(&dev->cbdev->queue_lock); 158 list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) { 159 if (cn_cb_equal(&i->id.id, &msg->id)) { 160 refcount_inc(&i->refcnt); 161 cbq = i; 162 break; 163 } 164 } 165 spin_unlock_bh(&dev->cbdev->queue_lock); 166 167 if (cbq != NULL) { 168 cbq->callback(msg, nsp); 169 kfree_skb(skb); 170 cn_queue_release_callback(cbq); 171 err = 0; 172 } 173 174 return err; 175 } 176 177 /* 178 * Main netlink receiving function. 179 * 180 * It checks skb, netlink header and msg sizes, and calls callback helper. 181 */ 182 static void cn_rx_skb(struct sk_buff *skb) 183 { 184 struct nlmsghdr *nlh; 185 int len, err; 186 187 if (skb->len >= NLMSG_HDRLEN) { 188 nlh = nlmsg_hdr(skb); 189 len = nlmsg_len(nlh); 190 191 if (len < (int)sizeof(struct cn_msg) || 192 skb->len < nlh->nlmsg_len || 193 len > CONNECTOR_MAX_MSG_SIZE) 194 return; 195 196 err = cn_call_callback(skb_get(skb)); 197 if (err < 0) 198 kfree_skb(skb); 199 } 200 } 201 202 /* 203 * Callback add routing - adds callback with given ID and name. 204 * If there is registered callback with the same ID it will not be added. 205 * 206 * May sleep. 207 */ 208 int cn_add_callback(struct cb_id *id, const char *name, 209 void (*callback)(struct cn_msg *, 210 struct netlink_skb_parms *)) 211 { 212 int err; 213 struct cn_dev *dev = &cdev; 214 215 if (!cn_already_initialized) 216 return -EAGAIN; 217 218 err = cn_queue_add_callback(dev->cbdev, name, id, callback); 219 if (err) 220 return err; 221 222 return 0; 223 } 224 EXPORT_SYMBOL_GPL(cn_add_callback); 225 226 /* 227 * Callback remove routing - removes callback 228 * with given ID. 229 * If there is no registered callback with given 230 * ID nothing happens. 231 * 232 * May sleep while waiting for reference counter to become zero. 233 */ 234 void cn_del_callback(struct cb_id *id) 235 { 236 struct cn_dev *dev = &cdev; 237 238 cn_queue_del_callback(dev->cbdev, id); 239 } 240 EXPORT_SYMBOL_GPL(cn_del_callback); 241 242 static int cn_proc_show(struct seq_file *m, void *v) 243 { 244 struct cn_queue_dev *dev = cdev.cbdev; 245 struct cn_callback_entry *cbq; 246 247 seq_printf(m, "Name ID\n"); 248 249 spin_lock_bh(&dev->queue_lock); 250 251 list_for_each_entry(cbq, &dev->queue_list, callback_entry) { 252 seq_printf(m, "%-15s %u:%u\n", 253 cbq->id.name, 254 cbq->id.id.idx, 255 cbq->id.id.val); 256 } 257 258 spin_unlock_bh(&dev->queue_lock); 259 260 return 0; 261 } 262 263 static int cn_proc_open(struct inode *inode, struct file *file) 264 { 265 return single_open(file, cn_proc_show, NULL); 266 } 267 268 static const struct file_operations cn_file_ops = { 269 .owner = THIS_MODULE, 270 .open = cn_proc_open, 271 .read = seq_read, 272 .llseek = seq_lseek, 273 .release = single_release 274 }; 275 276 static struct cn_dev cdev = { 277 .input = cn_rx_skb, 278 }; 279 280 static int cn_init(void) 281 { 282 struct cn_dev *dev = &cdev; 283 struct netlink_kernel_cfg cfg = { 284 .groups = CN_NETLINK_USERS + 0xf, 285 .input = dev->input, 286 }; 287 288 dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg); 289 if (!dev->nls) 290 return -EIO; 291 292 dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); 293 if (!dev->cbdev) { 294 netlink_kernel_release(dev->nls); 295 return -EINVAL; 296 } 297 298 cn_already_initialized = 1; 299 300 proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops); 301 302 return 0; 303 } 304 305 static void cn_fini(void) 306 { 307 struct cn_dev *dev = &cdev; 308 309 cn_already_initialized = 0; 310 311 remove_proc_entry("connector", init_net.proc_net); 312 313 cn_queue_free_dev(dev->cbdev); 314 netlink_kernel_release(dev->nls); 315 } 316 317 subsys_initcall(cn_init); 318 module_exit(cn_fini); 319