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