1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Generic HDLC support routines for Linux 4 * 5 * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl> 6 * 7 * Currently supported: 8 * * raw IP-in-HDLC 9 * * Cisco HDLC 10 * * Frame Relay with ANSI or CCITT LMI (both user and network side) 11 * * PPP 12 * * X.25 13 * 14 * Use sethdlc utility to set line parameters, protocol and PVCs 15 * 16 * How does it work: 17 * - proto->open(), close(), start(), stop() calls are serialized. 18 * The order is: open, [ start, stop ... ] close ... 19 * - proto->start() and stop() are called with spin_lock_irq held. 20 */ 21 22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 23 24 #include <linux/errno.h> 25 #include <linux/hdlc.h> 26 #include <linux/if_arp.h> 27 #include <linux/inetdevice.h> 28 #include <linux/init.h> 29 #include <linux/kernel.h> 30 #include <linux/module.h> 31 #include <linux/notifier.h> 32 #include <linux/pkt_sched.h> 33 #include <linux/poll.h> 34 #include <linux/rtnetlink.h> 35 #include <linux/skbuff.h> 36 #include <linux/slab.h> 37 #include <net/net_namespace.h> 38 39 40 static const char* version = "HDLC support module revision 1.22"; 41 42 #undef DEBUG_LINK 43 44 static struct hdlc_proto *first_proto; 45 46 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev, 47 struct packet_type *p, struct net_device *orig_dev) 48 { 49 struct hdlc_device *hdlc = dev_to_hdlc(dev); 50 51 if (!net_eq(dev_net(dev), &init_net)) { 52 kfree_skb(skb); 53 return 0; 54 } 55 56 BUG_ON(!hdlc->proto->netif_rx); 57 return hdlc->proto->netif_rx(skb); 58 } 59 60 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev) 61 { 62 hdlc_device *hdlc = dev_to_hdlc(dev); 63 64 if (hdlc->proto->xmit) 65 return hdlc->proto->xmit(skb, dev); 66 67 return hdlc->xmit(skb, dev); /* call hardware driver directly */ 68 } 69 70 static inline void hdlc_proto_start(struct net_device *dev) 71 { 72 hdlc_device *hdlc = dev_to_hdlc(dev); 73 if (hdlc->proto->start) 74 hdlc->proto->start(dev); 75 } 76 77 78 79 static inline void hdlc_proto_stop(struct net_device *dev) 80 { 81 hdlc_device *hdlc = dev_to_hdlc(dev); 82 if (hdlc->proto->stop) 83 hdlc->proto->stop(dev); 84 } 85 86 87 88 static int hdlc_device_event(struct notifier_block *this, unsigned long event, 89 void *ptr) 90 { 91 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 92 hdlc_device *hdlc; 93 unsigned long flags; 94 int on; 95 96 if (!net_eq(dev_net(dev), &init_net)) 97 return NOTIFY_DONE; 98 99 if (!(dev->priv_flags & IFF_WAN_HDLC)) 100 return NOTIFY_DONE; /* not an HDLC device */ 101 102 if (event != NETDEV_CHANGE) 103 return NOTIFY_DONE; /* Only interested in carrier changes */ 104 105 on = netif_carrier_ok(dev); 106 107 #ifdef DEBUG_LINK 108 printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n", 109 dev->name, on); 110 #endif 111 112 hdlc = dev_to_hdlc(dev); 113 spin_lock_irqsave(&hdlc->state_lock, flags); 114 115 if (hdlc->carrier == on) 116 goto carrier_exit; /* no change in DCD line level */ 117 118 hdlc->carrier = on; 119 120 if (!hdlc->open) 121 goto carrier_exit; 122 123 if (hdlc->carrier) { 124 netdev_info(dev, "Carrier detected\n"); 125 hdlc_proto_start(dev); 126 } else { 127 netdev_info(dev, "Carrier lost\n"); 128 hdlc_proto_stop(dev); 129 } 130 131 carrier_exit: 132 spin_unlock_irqrestore(&hdlc->state_lock, flags); 133 return NOTIFY_DONE; 134 } 135 136 137 138 /* Must be called by hardware driver when HDLC device is being opened */ 139 int hdlc_open(struct net_device *dev) 140 { 141 hdlc_device *hdlc = dev_to_hdlc(dev); 142 #ifdef DEBUG_LINK 143 printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name, 144 hdlc->carrier, hdlc->open); 145 #endif 146 147 if (hdlc->proto == NULL) 148 return -ENOSYS; /* no protocol attached */ 149 150 if (hdlc->proto->open) { 151 int result = hdlc->proto->open(dev); 152 if (result) 153 return result; 154 } 155 156 spin_lock_irq(&hdlc->state_lock); 157 158 if (hdlc->carrier) { 159 netdev_info(dev, "Carrier detected\n"); 160 hdlc_proto_start(dev); 161 } else 162 netdev_info(dev, "No carrier\n"); 163 164 hdlc->open = 1; 165 166 spin_unlock_irq(&hdlc->state_lock); 167 return 0; 168 } 169 170 171 172 /* Must be called by hardware driver when HDLC device is being closed */ 173 void hdlc_close(struct net_device *dev) 174 { 175 hdlc_device *hdlc = dev_to_hdlc(dev); 176 #ifdef DEBUG_LINK 177 printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name, 178 hdlc->carrier, hdlc->open); 179 #endif 180 181 spin_lock_irq(&hdlc->state_lock); 182 183 hdlc->open = 0; 184 if (hdlc->carrier) 185 hdlc_proto_stop(dev); 186 187 spin_unlock_irq(&hdlc->state_lock); 188 189 if (hdlc->proto->close) 190 hdlc->proto->close(dev); 191 } 192 193 194 195 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) 196 { 197 struct hdlc_proto *proto = first_proto; 198 int result; 199 200 if (cmd != SIOCWANDEV) 201 return -EINVAL; 202 203 if (dev_to_hdlc(dev)->proto) { 204 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr); 205 if (result != -EINVAL) 206 return result; 207 } 208 209 /* Not handled by currently attached protocol (if any) */ 210 211 while (proto) { 212 if ((result = proto->ioctl(dev, ifr)) != -EINVAL) 213 return result; 214 proto = proto->next; 215 } 216 return -EINVAL; 217 } 218 219 static const struct header_ops hdlc_null_ops; 220 221 static void hdlc_setup_dev(struct net_device *dev) 222 { 223 /* Re-init all variables changed by HDLC protocol drivers, 224 * including ether_setup() called from hdlc_raw_eth.c. 225 */ 226 dev->flags = IFF_POINTOPOINT | IFF_NOARP; 227 dev->priv_flags = IFF_WAN_HDLC; 228 dev->mtu = HDLC_MAX_MTU; 229 dev->min_mtu = 68; 230 dev->max_mtu = HDLC_MAX_MTU; 231 dev->type = ARPHRD_RAWHDLC; 232 dev->hard_header_len = 16; 233 dev->addr_len = 0; 234 dev->header_ops = &hdlc_null_ops; 235 } 236 237 static void hdlc_setup(struct net_device *dev) 238 { 239 hdlc_device *hdlc = dev_to_hdlc(dev); 240 241 hdlc_setup_dev(dev); 242 hdlc->carrier = 1; 243 hdlc->open = 0; 244 spin_lock_init(&hdlc->state_lock); 245 } 246 247 struct net_device *alloc_hdlcdev(void *priv) 248 { 249 struct net_device *dev; 250 dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d", 251 NET_NAME_UNKNOWN, hdlc_setup); 252 if (dev) 253 dev_to_hdlc(dev)->priv = priv; 254 return dev; 255 } 256 257 void unregister_hdlc_device(struct net_device *dev) 258 { 259 rtnl_lock(); 260 detach_hdlc_protocol(dev); 261 unregister_netdevice(dev); 262 rtnl_unlock(); 263 } 264 265 266 267 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto, 268 size_t size) 269 { 270 int err; 271 272 err = detach_hdlc_protocol(dev); 273 if (err) 274 return err; 275 276 if (!try_module_get(proto->module)) 277 return -ENOSYS; 278 279 if (size) { 280 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL); 281 if (dev_to_hdlc(dev)->state == NULL) { 282 module_put(proto->module); 283 return -ENOBUFS; 284 } 285 } 286 dev_to_hdlc(dev)->proto = proto; 287 288 return 0; 289 } 290 291 292 int detach_hdlc_protocol(struct net_device *dev) 293 { 294 hdlc_device *hdlc = dev_to_hdlc(dev); 295 int err; 296 297 if (hdlc->proto) { 298 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev); 299 err = notifier_to_errno(err); 300 if (err) { 301 netdev_err(dev, "Refused to change device type\n"); 302 return err; 303 } 304 305 if (hdlc->proto->detach) 306 hdlc->proto->detach(dev); 307 module_put(hdlc->proto->module); 308 hdlc->proto = NULL; 309 } 310 kfree(hdlc->state); 311 hdlc->state = NULL; 312 hdlc_setup_dev(dev); 313 314 return 0; 315 } 316 317 318 void register_hdlc_protocol(struct hdlc_proto *proto) 319 { 320 rtnl_lock(); 321 proto->next = first_proto; 322 first_proto = proto; 323 rtnl_unlock(); 324 } 325 326 327 void unregister_hdlc_protocol(struct hdlc_proto *proto) 328 { 329 struct hdlc_proto **p; 330 331 rtnl_lock(); 332 p = &first_proto; 333 while (*p != proto) { 334 BUG_ON(!*p); 335 p = &((*p)->next); 336 } 337 *p = proto->next; 338 rtnl_unlock(); 339 } 340 341 342 343 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>"); 344 MODULE_DESCRIPTION("HDLC support module"); 345 MODULE_LICENSE("GPL v2"); 346 347 EXPORT_SYMBOL(hdlc_start_xmit); 348 EXPORT_SYMBOL(hdlc_open); 349 EXPORT_SYMBOL(hdlc_close); 350 EXPORT_SYMBOL(hdlc_ioctl); 351 EXPORT_SYMBOL(alloc_hdlcdev); 352 EXPORT_SYMBOL(unregister_hdlc_device); 353 EXPORT_SYMBOL(register_hdlc_protocol); 354 EXPORT_SYMBOL(unregister_hdlc_protocol); 355 EXPORT_SYMBOL(attach_hdlc_protocol); 356 EXPORT_SYMBOL(detach_hdlc_protocol); 357 358 static struct packet_type hdlc_packet_type __read_mostly = { 359 .type = cpu_to_be16(ETH_P_HDLC), 360 .func = hdlc_rcv, 361 }; 362 363 364 static struct notifier_block hdlc_notifier = { 365 .notifier_call = hdlc_device_event, 366 }; 367 368 369 static int __init hdlc_module_init(void) 370 { 371 int result; 372 373 pr_info("%s\n", version); 374 if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0) 375 return result; 376 dev_add_pack(&hdlc_packet_type); 377 return 0; 378 } 379 380 381 382 static void __exit hdlc_module_exit(void) 383 { 384 dev_remove_pack(&hdlc_packet_type); 385 unregister_netdevice_notifier(&hdlc_notifier); 386 } 387 388 389 module_init(hdlc_module_init); 390 module_exit(hdlc_module_exit); 391