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 <linux/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 40 static struct cn_dev cdev; 41 42 static int cn_already_initialized; 43 44 /* 45 * msg->seq and msg->ack are used to determine message genealogy. 46 * When someone sends message it puts there locally unique sequence 47 * and random acknowledge numbers. Sequence number may be copied into 48 * nlmsghdr->nlmsg_seq too. 49 * 50 * Sequence number is incremented with each message to be sent. 51 * 52 * If we expect reply to our message then the sequence number in 53 * received message MUST be the same as in original message, and 54 * acknowledge number MUST be the same + 1. 55 * 56 * If we receive a message and its sequence number is not equal to the 57 * one we are expecting then it is a new message. 58 * 59 * If we receive a message and its sequence number is the same as one 60 * we are expecting but it's acknowledgement number is not equal to 61 * the acknowledgement number in the original message + 1, then it is 62 * a new message. 63 * 64 */ 65 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask) 66 { 67 struct cn_callback_entry *__cbq; 68 unsigned int size; 69 struct sk_buff *skb; 70 struct nlmsghdr *nlh; 71 struct cn_msg *data; 72 struct cn_dev *dev = &cdev; 73 u32 group = 0; 74 int found = 0; 75 76 if (!__group) { 77 spin_lock_bh(&dev->cbdev->queue_lock); 78 list_for_each_entry(__cbq, &dev->cbdev->queue_list, 79 callback_entry) { 80 if (cn_cb_equal(&__cbq->id.id, &msg->id)) { 81 found = 1; 82 group = __cbq->group; 83 break; 84 } 85 } 86 spin_unlock_bh(&dev->cbdev->queue_lock); 87 88 if (!found) 89 return -ENODEV; 90 } else { 91 group = __group; 92 } 93 94 if (!netlink_has_listeners(dev->nls, group)) 95 return -ESRCH; 96 97 size = NLMSG_SPACE(sizeof(*msg) + msg->len); 98 99 skb = alloc_skb(size, gfp_mask); 100 if (!skb) 101 return -ENOMEM; 102 103 nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh)); 104 105 data = NLMSG_DATA(nlh); 106 107 memcpy(data, msg, sizeof(*data) + msg->len); 108 109 NETLINK_CB(skb).dst_group = group; 110 111 return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask); 112 113 nlmsg_failure: 114 kfree_skb(skb); 115 return -EINVAL; 116 } 117 EXPORT_SYMBOL_GPL(cn_netlink_send); 118 119 /* 120 * Callback helper - queues work and setup destructor for given data. 121 */ 122 static int cn_call_callback(struct sk_buff *skb) 123 { 124 struct cn_callback_entry *__cbq, *__new_cbq; 125 struct cn_dev *dev = &cdev; 126 struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb)); 127 int err = -ENODEV; 128 129 spin_lock_bh(&dev->cbdev->queue_lock); 130 list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) { 131 if (cn_cb_equal(&__cbq->id.id, &msg->id)) { 132 if (likely(!work_pending(&__cbq->work) && 133 __cbq->data.skb == NULL)) { 134 __cbq->data.skb = skb; 135 136 if (queue_work(dev->cbdev->cn_queue, 137 &__cbq->work)) 138 err = 0; 139 else 140 err = -EINVAL; 141 } else { 142 struct cn_callback_data *d; 143 144 err = -ENOMEM; 145 __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC); 146 if (__new_cbq) { 147 d = &__new_cbq->data; 148 d->skb = skb; 149 d->callback = __cbq->data.callback; 150 d->free = __new_cbq; 151 152 INIT_WORK(&__new_cbq->work, 153 &cn_queue_wrapper); 154 155 if (queue_work(dev->cbdev->cn_queue, 156 &__new_cbq->work)) 157 err = 0; 158 else { 159 kfree(__new_cbq); 160 err = -EINVAL; 161 } 162 } 163 } 164 break; 165 } 166 } 167 spin_unlock_bh(&dev->cbdev->queue_lock); 168 169 return err; 170 } 171 172 /* 173 * Main netlink receiving function. 174 * 175 * It checks skb, netlink header and msg sizes, and calls callback helper. 176 */ 177 static void cn_rx_skb(struct sk_buff *__skb) 178 { 179 struct nlmsghdr *nlh; 180 int err; 181 struct sk_buff *skb; 182 183 skb = skb_get(__skb); 184 185 if (skb->len >= NLMSG_SPACE(0)) { 186 nlh = nlmsg_hdr(skb); 187 188 if (nlh->nlmsg_len < sizeof(struct cn_msg) || 189 skb->len < nlh->nlmsg_len || 190 nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) { 191 kfree_skb(skb); 192 return; 193 } 194 195 err = cn_call_callback(skb); 196 if (err < 0) 197 kfree_skb(skb); 198 } 199 } 200 201 /* 202 * Callback add routing - adds callback with given ID and name. 203 * If there is registered callback with the same ID it will not be added. 204 * 205 * May sleep. 206 */ 207 int cn_add_callback(struct cb_id *id, char *name, 208 void (*callback)(struct cn_msg *, 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 int __devinit cn_init(void) 275 { 276 struct cn_dev *dev = &cdev; 277 278 dev->input = cn_rx_skb; 279 280 dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, 281 CN_NETLINK_USERS + 0xf, 282 dev->input, NULL, THIS_MODULE); 283 if (!dev->nls) 284 return -EIO; 285 286 dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); 287 if (!dev->cbdev) { 288 netlink_kernel_release(dev->nls); 289 return -EINVAL; 290 } 291 292 cn_already_initialized = 1; 293 294 proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops); 295 296 return 0; 297 } 298 299 static void __devexit cn_fini(void) 300 { 301 struct cn_dev *dev = &cdev; 302 303 cn_already_initialized = 0; 304 305 proc_net_remove(&init_net, "connector"); 306 307 cn_queue_free_dev(dev->cbdev); 308 netlink_kernel_release(dev->nls); 309 } 310 311 subsys_initcall(cn_init); 312 module_exit(cn_fini); 313