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_cn_work(__cbq, &__cbq->work)) 137 err = 0; 138 else 139 err = -EINVAL; 140 } else { 141 struct cn_callback_data *d; 142 143 err = -ENOMEM; 144 __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC); 145 if (__new_cbq) { 146 d = &__new_cbq->data; 147 d->skb = skb; 148 d->callback = __cbq->data.callback; 149 d->free = __new_cbq; 150 151 __new_cbq->pdev = __cbq->pdev; 152 153 INIT_WORK(&__new_cbq->work, 154 &cn_queue_wrapper); 155 156 if (queue_cn_work(__new_cbq, 157 &__new_cbq->work)) 158 err = 0; 159 else { 160 kfree(__new_cbq); 161 err = -EINVAL; 162 } 163 } 164 } 165 break; 166 } 167 } 168 spin_unlock_bh(&dev->cbdev->queue_lock); 169 170 return err; 171 } 172 173 /* 174 * Main netlink receiving function. 175 * 176 * It checks skb, netlink header and msg sizes, and calls callback helper. 177 */ 178 static void cn_rx_skb(struct sk_buff *__skb) 179 { 180 struct nlmsghdr *nlh; 181 int err; 182 struct sk_buff *skb; 183 184 skb = skb_get(__skb); 185 186 if (skb->len >= NLMSG_SPACE(0)) { 187 nlh = nlmsg_hdr(skb); 188 189 if (nlh->nlmsg_len < sizeof(struct cn_msg) || 190 skb->len < nlh->nlmsg_len || 191 nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) { 192 kfree_skb(skb); 193 return; 194 } 195 196 err = cn_call_callback(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, char *name, 209 void (*callback)(struct cn_msg *, struct netlink_skb_parms *)) 210 { 211 int err; 212 struct cn_dev *dev = &cdev; 213 214 if (!cn_already_initialized) 215 return -EAGAIN; 216 217 err = cn_queue_add_callback(dev->cbdev, name, id, callback); 218 if (err) 219 return err; 220 221 return 0; 222 } 223 EXPORT_SYMBOL_GPL(cn_add_callback); 224 225 /* 226 * Callback remove routing - removes callback 227 * with given ID. 228 * If there is no registered callback with given 229 * ID nothing happens. 230 * 231 * May sleep while waiting for reference counter to become zero. 232 */ 233 void cn_del_callback(struct cb_id *id) 234 { 235 struct cn_dev *dev = &cdev; 236 237 cn_queue_del_callback(dev->cbdev, id); 238 } 239 EXPORT_SYMBOL_GPL(cn_del_callback); 240 241 static int cn_proc_show(struct seq_file *m, void *v) 242 { 243 struct cn_queue_dev *dev = cdev.cbdev; 244 struct cn_callback_entry *cbq; 245 246 seq_printf(m, "Name ID\n"); 247 248 spin_lock_bh(&dev->queue_lock); 249 250 list_for_each_entry(cbq, &dev->queue_list, callback_entry) { 251 seq_printf(m, "%-15s %u:%u\n", 252 cbq->id.name, 253 cbq->id.id.idx, 254 cbq->id.id.val); 255 } 256 257 spin_unlock_bh(&dev->queue_lock); 258 259 return 0; 260 } 261 262 static int cn_proc_open(struct inode *inode, struct file *file) 263 { 264 return single_open(file, cn_proc_show, NULL); 265 } 266 267 static const struct file_operations cn_file_ops = { 268 .owner = THIS_MODULE, 269 .open = cn_proc_open, 270 .read = seq_read, 271 .llseek = seq_lseek, 272 .release = single_release 273 }; 274 275 static int __devinit cn_init(void) 276 { 277 struct cn_dev *dev = &cdev; 278 279 dev->input = cn_rx_skb; 280 281 dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, 282 CN_NETLINK_USERS + 0xf, 283 dev->input, NULL, THIS_MODULE); 284 if (!dev->nls) 285 return -EIO; 286 287 dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); 288 if (!dev->cbdev) { 289 netlink_kernel_release(dev->nls); 290 return -EINVAL; 291 } 292 293 cn_already_initialized = 1; 294 295 proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops); 296 297 return 0; 298 } 299 300 static void __devexit cn_fini(void) 301 { 302 struct cn_dev *dev = &cdev; 303 304 cn_already_initialized = 0; 305 306 proc_net_remove(&init_net, "connector"); 307 308 cn_queue_free_dev(dev->cbdev); 309 netlink_kernel_release(dev->nls); 310 } 311 312 subsys_initcall(cn_init); 313 module_exit(cn_fini); 314