1 /* net/atm/pppoatm.c - RFC2364 PPP over ATM/AAL5 */ 2 3 /* Copyright 1999-2000 by Mitchell Blank Jr */ 4 /* Based on clip.c; 1995-1999 by Werner Almesberger, EPFL LRC/ICA */ 5 /* And on ppp_async.c; Copyright 1999 Paul Mackerras */ 6 /* And help from Jens Axboe */ 7 8 /* 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 * 14 * This driver provides the encapsulation and framing for sending 15 * and receiving PPP frames in ATM AAL5 PDUs. 16 */ 17 18 /* 19 * One shortcoming of this driver is that it does not comply with 20 * section 8 of RFC2364 - we are supposed to detect a change 21 * in encapsulation and immediately abort the connection (in order 22 * to avoid a black-hole being created if our peer loses state 23 * and changes encapsulation unilaterally. However, since the 24 * ppp_generic layer actually does the decapsulation, we need 25 * a way of notifying it when we _think_ there might be a problem) 26 * There's two cases: 27 * 1. LLC-encapsulation was missing when it was enabled. In 28 * this case, we should tell the upper layer "tear down 29 * this session if this skb looks ok to you" 30 * 2. LLC-encapsulation was present when it was disabled. Then 31 * we need to tell the upper layer "this packet may be 32 * ok, but if its in error tear down the session" 33 * These hooks are not yet available in ppp_generic 34 */ 35 36 #include <linux/module.h> 37 #include <linux/config.h> 38 #include <linux/init.h> 39 #include <linux/skbuff.h> 40 #include <linux/atm.h> 41 #include <linux/atmdev.h> 42 #include <linux/ppp_defs.h> 43 #include <linux/if_ppp.h> 44 #include <linux/ppp_channel.h> 45 #include <linux/atmppp.h> 46 47 #include "common.h" 48 49 #if 0 50 #define DPRINTK(format, args...) \ 51 printk(KERN_DEBUG "pppoatm: " format, ##args) 52 #else 53 #define DPRINTK(format, args...) 54 #endif 55 56 enum pppoatm_encaps { 57 e_autodetect = PPPOATM_ENCAPS_AUTODETECT, 58 e_vc = PPPOATM_ENCAPS_VC, 59 e_llc = PPPOATM_ENCAPS_LLC, 60 }; 61 62 struct pppoatm_vcc { 63 struct atm_vcc *atmvcc; /* VCC descriptor */ 64 void (*old_push)(struct atm_vcc *, struct sk_buff *); 65 void (*old_pop)(struct atm_vcc *, struct sk_buff *); 66 /* keep old push/pop for detaching */ 67 enum pppoatm_encaps encaps; 68 int flags; /* SC_COMP_PROT - compress protocol */ 69 struct ppp_channel chan; /* interface to generic ppp layer */ 70 struct tasklet_struct wakeup_tasklet; 71 }; 72 73 /* 74 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol 75 * ID (0xC021) used in autodetection 76 */ 77 static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 }; 78 #define LLC_LEN (4) 79 80 static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc) 81 { 82 return (struct pppoatm_vcc *) (atmvcc->user_back); 83 } 84 85 static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan) 86 { 87 return (struct pppoatm_vcc *) (chan->private); 88 } 89 90 /* 91 * We can't do this directly from our _pop handler, since the ppp code 92 * doesn't want to be called in interrupt context, so we do it from 93 * a tasklet 94 */ 95 static void pppoatm_wakeup_sender(unsigned long arg) 96 { 97 ppp_output_wakeup((struct ppp_channel *) arg); 98 } 99 100 /* 101 * This gets called every time the ATM card has finished sending our 102 * skb. The ->old_pop will take care up normal atm flow control, 103 * but we also need to wake up the device if we blocked it 104 */ 105 static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb) 106 { 107 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); 108 pvcc->old_pop(atmvcc, skb); 109 /* 110 * We don't really always want to do this since it's 111 * really inefficient - it would be much better if we could 112 * test if we had actually throttled the generic layer. 113 * Unfortunately then there would be a nasty SMP race where 114 * we could clear that flag just as we refuse another packet. 115 * For now we do the safe thing. 116 */ 117 tasklet_schedule(&pvcc->wakeup_tasklet); 118 } 119 120 /* 121 * Unbind from PPP - currently we only do this when closing the socket, 122 * but we could put this into an ioctl if need be 123 */ 124 static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc) 125 { 126 struct pppoatm_vcc *pvcc; 127 pvcc = atmvcc_to_pvcc(atmvcc); 128 atmvcc->push = pvcc->old_push; 129 atmvcc->pop = pvcc->old_pop; 130 tasklet_kill(&pvcc->wakeup_tasklet); 131 ppp_unregister_channel(&pvcc->chan); 132 atmvcc->user_back = NULL; 133 kfree(pvcc); 134 /* Gee, I hope we have the big kernel lock here... */ 135 module_put(THIS_MODULE); 136 } 137 138 /* Called when an AAL5 PDU comes in */ 139 static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb) 140 { 141 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); 142 DPRINTK("pppoatm push\n"); 143 if (skb == NULL) { /* VCC was closed */ 144 DPRINTK("removing ATMPPP VCC %p\n", pvcc); 145 pppoatm_unassign_vcc(atmvcc); 146 atmvcc->push(atmvcc, NULL); /* Pass along bad news */ 147 return; 148 } 149 atm_return(atmvcc, skb->truesize); 150 switch (pvcc->encaps) { 151 case e_llc: 152 if (skb->len < LLC_LEN || 153 memcmp(skb->data, pppllc, LLC_LEN)) 154 goto error; 155 skb_pull(skb, LLC_LEN); 156 break; 157 case e_autodetect: 158 if (pvcc->chan.ppp == NULL) { /* Not bound yet! */ 159 kfree_skb(skb); 160 return; 161 } 162 if (skb->len >= sizeof(pppllc) && 163 !memcmp(skb->data, pppllc, sizeof(pppllc))) { 164 pvcc->encaps = e_llc; 165 skb_pull(skb, LLC_LEN); 166 break; 167 } 168 if (skb->len >= (sizeof(pppllc) - LLC_LEN) && 169 !memcmp(skb->data, &pppllc[LLC_LEN], 170 sizeof(pppllc) - LLC_LEN)) { 171 pvcc->encaps = e_vc; 172 pvcc->chan.mtu += LLC_LEN; 173 break; 174 } 175 DPRINTK("(unit %d): Couldn't autodetect yet " 176 "(skb: %02X %02X %02X %02X %02X %02X)\n", 177 pvcc->chan.unit, 178 skb->data[0], skb->data[1], skb->data[2], 179 skb->data[3], skb->data[4], skb->data[5]); 180 goto error; 181 case e_vc: 182 break; 183 } 184 ppp_input(&pvcc->chan, skb); 185 return; 186 error: 187 kfree_skb(skb); 188 ppp_input_error(&pvcc->chan, 0); 189 } 190 191 /* 192 * Called by the ppp_generic.c to send a packet - returns true if packet 193 * was accepted. If we return false, then it's our job to call 194 * ppp_output_wakeup(chan) when we're feeling more up to it. 195 * Note that in the ENOMEM case (as opposed to the !atm_may_send case) 196 * we should really drop the packet, but the generic layer doesn't 197 * support this yet. We just return 'DROP_PACKET' which we actually define 198 * as success, just to be clear what we're really doing. 199 */ 200 #define DROP_PACKET 1 201 static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) 202 { 203 struct pppoatm_vcc *pvcc = chan_to_pvcc(chan); 204 ATM_SKB(skb)->vcc = pvcc->atmvcc; 205 DPRINTK("(unit %d): pppoatm_send (skb=0x%p, vcc=0x%p)\n", 206 pvcc->chan.unit, skb, pvcc->atmvcc); 207 if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT)) 208 (void) skb_pull(skb, 1); 209 switch (pvcc->encaps) { /* LLC encapsulation needed */ 210 case e_llc: 211 if (skb_headroom(skb) < LLC_LEN) { 212 struct sk_buff *n; 213 n = skb_realloc_headroom(skb, LLC_LEN); 214 if (n != NULL && 215 !atm_may_send(pvcc->atmvcc, n->truesize)) { 216 kfree_skb(n); 217 goto nospace; 218 } 219 kfree_skb(skb); 220 if ((skb = n) == NULL) 221 return DROP_PACKET; 222 } else if (!atm_may_send(pvcc->atmvcc, skb->truesize)) 223 goto nospace; 224 memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN); 225 break; 226 case e_vc: 227 if (!atm_may_send(pvcc->atmvcc, skb->truesize)) 228 goto nospace; 229 break; 230 case e_autodetect: 231 DPRINTK("(unit %d): Trying to send without setting encaps!\n", 232 pvcc->chan.unit); 233 kfree_skb(skb); 234 return 1; 235 } 236 237 atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc); 238 ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options; 239 DPRINTK("(unit %d): atm_skb(%p)->vcc(%p)->dev(%p)\n", 240 pvcc->chan.unit, skb, ATM_SKB(skb)->vcc, 241 ATM_SKB(skb)->vcc->dev); 242 return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb) 243 ? DROP_PACKET : 1; 244 nospace: 245 /* 246 * We don't have space to send this SKB now, but we might have 247 * already applied SC_COMP_PROT compression, so may need to undo 248 */ 249 if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 && 250 skb->data[-1] == '\0') 251 (void) skb_push(skb, 1); 252 return 0; 253 } 254 255 /* This handles ioctls sent to the /dev/ppp interface */ 256 static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd, 257 unsigned long arg) 258 { 259 switch (cmd) { 260 case PPPIOCGFLAGS: 261 return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg) 262 ? -EFAULT : 0; 263 case PPPIOCSFLAGS: 264 return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg) 265 ? -EFAULT : 0; 266 } 267 return -ENOTTY; 268 } 269 270 static /*const*/ struct ppp_channel_ops pppoatm_ops = { 271 .start_xmit = pppoatm_send, 272 .ioctl = pppoatm_devppp_ioctl, 273 }; 274 275 static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg) 276 { 277 struct atm_backend_ppp be; 278 struct pppoatm_vcc *pvcc; 279 int err; 280 /* 281 * Each PPPoATM instance has its own tasklet - this is just a 282 * prototypical one used to initialize them 283 */ 284 static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0); 285 if (copy_from_user(&be, arg, sizeof be)) 286 return -EFAULT; 287 if (be.encaps != PPPOATM_ENCAPS_AUTODETECT && 288 be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC) 289 return -EINVAL; 290 pvcc = kmalloc(sizeof(*pvcc), GFP_KERNEL); 291 if (pvcc == NULL) 292 return -ENOMEM; 293 memset(pvcc, 0, sizeof(*pvcc)); 294 pvcc->atmvcc = atmvcc; 295 pvcc->old_push = atmvcc->push; 296 pvcc->old_pop = atmvcc->pop; 297 pvcc->encaps = (enum pppoatm_encaps) be.encaps; 298 pvcc->chan.private = pvcc; 299 pvcc->chan.ops = &pppoatm_ops; 300 pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN - 301 (be.encaps == e_vc ? 0 : LLC_LEN); 302 pvcc->wakeup_tasklet = tasklet_proto; 303 pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan; 304 if ((err = ppp_register_channel(&pvcc->chan)) != 0) { 305 kfree(pvcc); 306 return err; 307 } 308 atmvcc->user_back = pvcc; 309 atmvcc->push = pppoatm_push; 310 atmvcc->pop = pppoatm_pop; 311 __module_get(THIS_MODULE); 312 return 0; 313 } 314 315 /* 316 * This handles ioctls actually performed on our vcc - we must return 317 * -ENOIOCTLCMD for any unrecognized ioctl 318 */ 319 static int pppoatm_ioctl(struct socket *sock, unsigned int cmd, 320 unsigned long arg) 321 { 322 struct atm_vcc *atmvcc = ATM_SD(sock); 323 void __user *argp = (void __user *)arg; 324 325 if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push) 326 return -ENOIOCTLCMD; 327 switch (cmd) { 328 case ATM_SETBACKEND: { 329 atm_backend_t b; 330 if (get_user(b, (atm_backend_t __user *) argp)) 331 return -EFAULT; 332 if (b != ATM_BACKEND_PPP) 333 return -ENOIOCTLCMD; 334 if (!capable(CAP_NET_ADMIN)) 335 return -EPERM; 336 return pppoatm_assign_vcc(atmvcc, argp); 337 } 338 case PPPIOCGCHAN: 339 return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)-> 340 chan), (int __user *) argp) ? -EFAULT : 0; 341 case PPPIOCGUNIT: 342 return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)-> 343 chan), (int __user *) argp) ? -EFAULT : 0; 344 } 345 return -ENOIOCTLCMD; 346 } 347 348 static struct atm_ioctl pppoatm_ioctl_ops = { 349 .owner = THIS_MODULE, 350 .ioctl = pppoatm_ioctl, 351 }; 352 353 static int __init pppoatm_init(void) 354 { 355 register_atm_ioctl(&pppoatm_ioctl_ops); 356 return 0; 357 } 358 359 static void __exit pppoatm_exit(void) 360 { 361 deregister_atm_ioctl(&pppoatm_ioctl_ops); 362 } 363 364 module_init(pppoatm_init); 365 module_exit(pppoatm_exit); 366 367 MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>"); 368 MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5"); 369 MODULE_LICENSE("GPL"); 370