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#define DPRINTK(format, args...) 48 49enum pppoatm_encaps { 50 e_autodetect = PPPOATM_ENCAPS_AUTODETECT, 51 e_vc = PPPOATM_ENCAPS_VC, 52 e_llc = PPPOATM_ENCAPS_LLC, 53}; 54 55struct pppoatm_vcc { 56 struct atm_vcc *atmvcc; /* VCC descriptor */ 57 void (*old_push)(struct atm_vcc *, struct sk_buff *); 58 void (*old_pop)(struct atm_vcc *, struct sk_buff *); 59 /* keep old push/pop for detaching */ 60 enum pppoatm_encaps encaps; 61 int flags; /* SC_COMP_PROT - compress protocol */ 62 struct ppp_channel chan; /* interface to generic ppp layer */ 63 struct tasklet_struct wakeup_tasklet; 64}; 65 66/* 67 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol 68 * ID (0xC021) used in autodetection 69 */ 70static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 }; 71#define LLC_LEN (4) 72 73static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc) 74{ 75 return (struct pppoatm_vcc *) (atmvcc->user_back); 76} 77 78static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan) 79{ 80 return (struct pppoatm_vcc *) (chan->private); 81} 82 83/* 84 * We can't do this directly from our _pop handler, since the ppp code 85 * doesn't want to be called in interrupt context, so we do it from 86 * a tasklet 87 */ 88static void pppoatm_wakeup_sender(unsigned long arg) 89{ 90 ppp_output_wakeup((struct ppp_channel *) arg); 91} 92 93/* 94 * This gets called every time the ATM card has finished sending our 95 * skb. The ->old_pop will take care up normal atm flow control, 96 * but we also need to wake up the device if we blocked it 97 */ 98static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb) 99{ 100 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); 101 pvcc->old_pop(atmvcc, skb); 102 /* 103 * We don't really always want to do this since it's 104 * really inefficient - it would be much better if we could 105 * test if we had actually throttled the generic layer. 106 * Unfortunately then there would be a nasty SMP race where 107 * we could clear that flag just as we refuse another packet. 108 * For now we do the safe thing. 109 */ 110 tasklet_schedule(&pvcc->wakeup_tasklet); 111} 112 113/* 114 * Unbind from PPP - currently we only do this when closing the socket, 115 * but we could put this into an ioctl if need be 116 */ 117static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc) 118{ 119 struct pppoatm_vcc *pvcc; 120 pvcc = atmvcc_to_pvcc(atmvcc); 121 atmvcc->push = pvcc->old_push; 122 atmvcc->pop = pvcc->old_pop; 123 tasklet_kill(&pvcc->wakeup_tasklet); 124 ppp_unregister_channel(&pvcc->chan); 125 atmvcc->user_back = NULL; 126 kfree(pvcc); 127 /* Gee, I hope we have the big kernel lock here... */ 128 MOD_DEC_USE_COUNT; 129} 130 131/* Called when an AAL5 PDU comes in */ 132static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb) 133{ 134 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); 135 DPRINTK("pppoatm push\n"); 136 if (skb == NULL) { /* VCC was closed */ 137 DPRINTK("removing ATMPPP VCC %p\n", pvcc); 138 pppoatm_unassign_vcc(atmvcc); 139 atmvcc->push(atmvcc, NULL); /* Pass along bad news */ 140 return; 141 } 142 atm_return(atmvcc, skb->truesize); 143 switch (pvcc->encaps) { 144 case e_llc: 145 if (skb->len < LLC_LEN || 146 memcmp(skb->data, pppllc, LLC_LEN)) 147 goto error; 148 skb_pull(skb, LLC_LEN); 149 break; 150 case e_autodetect: 151 if (pvcc->chan.ppp == NULL) { /* Not bound yet! */ 152 kfree_skb(skb); 153 return; 154 } 155 if (skb->len >= sizeof(pppllc) && 156 !memcmp(skb->data, pppllc, sizeof(pppllc))) { 157 pvcc->encaps = e_llc; 158 skb_pull(skb, LLC_LEN); 159 break; 160 } 161 if (skb->len >= (sizeof(pppllc) - LLC_LEN) && 162 !memcmp(skb->data, &pppllc[LLC_LEN], 163 sizeof(pppllc) - LLC_LEN)) { 164 pvcc->encaps = e_vc; 165 pvcc->chan.mtu += LLC_LEN; 166 break; 167 } 168 DPRINTK("(unit %d): Couldn't autodetect yet " 169 "(skb: %02X %02X %02X %02X %02X %02X)\n", 170 pvcc->chan.unit, 171 skb->data[0], skb->data[1], skb->data[2], 172 skb->data[3], skb->data[4], skb->data[5]); 173 goto error; 174 case e_vc: 175 break; 176 } 177 ppp_input(&pvcc->chan, skb); 178 return; 179 error: 180 kfree_skb(skb); 181 ppp_input_error(&pvcc->chan, 0); 182} 183 184/* 185 * Called by the ppp_generic.c to send a packet - returns true if packet 186 * was accepted. If we return false, then it's our job to call 187 * ppp_output_wakeup(chan) when we're feeling more up to it. 188 * Note that in the ENOMEM case (as opposed to the !atm_may_send case) 189 * we should really drop the packet, but the generic layer doesn't 190 * support this yet. We just return 'DROP_PACKET' which we actually define 191 * as success, just to be clear what we're really doing. 192 */ 193#define DROP_PACKET 1 194static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) 195{ 196 struct pppoatm_vcc *pvcc = chan_to_pvcc(chan); 197 ATM_SKB(skb)->vcc = pvcc->atmvcc; 198 DPRINTK("(unit %d): pppoatm_send (skb=0x%p, vcc=0x%p)\n", 199 pvcc->chan.unit, skb, pvcc->atmvcc); 200 if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT)) 201 (void) skb_pull(skb, 1); 202 switch (pvcc->encaps) { /* LLC encapsulation needed */ 203 case e_llc: 204 if (skb_headroom(skb) < LLC_LEN) { 205 struct sk_buff *n; 206 n = skb_realloc_headroom(skb, LLC_LEN); 207 if (n != NULL && 208 !atm_may_send(pvcc->atmvcc, n->truesize)) { 209 kfree_skb(n); 210 goto nospace; 211 } 212 kfree_skb(skb); 213 if ((skb = n) == NULL) 214 return DROP_PACKET; 215 } else if (!atm_may_send(pvcc->atmvcc, skb->truesize)) 216 goto nospace; 217 memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN); 218 break; 219 case e_vc: 220 if (!atm_may_send(pvcc->atmvcc, skb->truesize)) 221 goto nospace; 222 break; 223 case e_autodetect: 224 DPRINTK("(unit %d): Trying to send without setting encaps!\n", 225 pvcc->chan.unit); 226 kfree_skb(skb); 227 return 1; 228 } 229 atomic_add(skb->truesize, &ATM_SKB(skb)->vcc->tx_inuse); 230 ATM_SKB(skb)->iovcnt = 0; 231 ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options; 232 DPRINTK("(unit %d): atm_skb(%p)->vcc(%p)->dev(%p)\n", 233 pvcc->chan.unit, skb, ATM_SKB(skb)->vcc, 234 ATM_SKB(skb)->vcc->dev); 235 return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb) 236 ? DROP_PACKET : 1; 237 nospace: 238 /* 239 * We don't have space to send this SKB now, but we might have 240 * already applied SC_COMP_PROT compression, so may need to undo 241 */ 242 if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 && 243 skb->data[-1] == '\0') 244 (void) skb_push(skb, 1); 245 return 0; 246} 247 248/* This handles ioctls sent to the /dev/ppp interface */ 249static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd, 250 unsigned long arg) 251{ 252 switch (cmd) { 253 case PPPIOCGFLAGS: 254 return put_user(chan_to_pvcc(chan)->flags, (int *) arg) 255 ? -EFAULT : 0; 256 case PPPIOCSFLAGS: 257 return get_user(chan_to_pvcc(chan)->flags, (int *) arg) 258 ? -EFAULT : 0; 259 } 260 return -ENOTTY; 261} 262 263static /*const*/ struct ppp_channel_ops pppoatm_ops = { 264 start_xmit: pppoatm_send, 265 ioctl: pppoatm_devppp_ioctl, 266}; 267 268static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, unsigned long arg) 269{ 270 struct atm_backend_ppp be; 271 struct pppoatm_vcc *pvcc; 272 int err; 273 /* 274 * Each PPPoATM instance has its own tasklet - this is just a 275 * prototypical one used to initialize them 276 */ 277 static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0); 278 if (copy_from_user(&be, (void *) arg, sizeof be)) 279 return -EFAULT; 280 if (be.encaps != PPPOATM_ENCAPS_AUTODETECT && 281 be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC) 282 return -EINVAL; 283 MOD_INC_USE_COUNT; 284 pvcc = kmalloc(sizeof(*pvcc), GFP_KERNEL); 285 if (pvcc == NULL) { 286 MOD_DEC_USE_COUNT; 287 return -ENOMEM; 288 } 289 memset(pvcc, 0, sizeof(*pvcc)); 290 pvcc->atmvcc = atmvcc; 291 pvcc->old_push = atmvcc->push; 292 pvcc->old_pop = atmvcc->pop; 293 pvcc->encaps = (enum pppoatm_encaps) be.encaps; 294 pvcc->chan.private = pvcc; 295 pvcc->chan.ops = &pppoatm_ops; 296 pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN - 297 (be.encaps == e_vc ? 0 : LLC_LEN); 298 pvcc->wakeup_tasklet = tasklet_proto; 299 pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan; 300 if ((err = ppp_register_channel(&pvcc->chan)) != 0) { 301 kfree(pvcc); 302 return err; 303 } 304 atmvcc->user_back = pvcc; 305 atmvcc->push = pppoatm_push; 306 atmvcc->pop = pppoatm_pop; 307 return 0; 308} 309 310/* 311 * This handles ioctls actually performed on our vcc - we must return 312 * -ENOIOCTLCMD for any unrecognized ioctl 313 */ 314static int pppoatm_ioctl(struct atm_vcc *atmvcc, unsigned int cmd, 315 unsigned long arg) 316{ 317 if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push) 318 return -ENOIOCTLCMD; 319 switch (cmd) { 320 case ATM_SETBACKEND: { 321 atm_backend_t b; 322 if (get_user(b, (atm_backend_t *) arg)) 323 return -EFAULT; 324 if (b != ATM_BACKEND_PPP) 325 return -ENOIOCTLCMD; 326 if (!capable(CAP_NET_ADMIN)) 327 return -EPERM; 328 return pppoatm_assign_vcc(atmvcc, arg); 329 } 330 case PPPIOCGCHAN: 331 return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)-> 332 chan), (int *) arg) ? -EFAULT : 0; 333 case PPPIOCGUNIT: 334 return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)-> 335 chan), (int *) arg) ? -EFAULT : 0; 336 } 337 return -ENOIOCTLCMD; 338} 339 340/* the following avoids some spurious warnings from the compiler */ 341#define UNUSED __attribute__((unused)) 342 343extern int (*pppoatm_ioctl_hook)(struct atm_vcc *, unsigned int, unsigned long); 344 345static int __init UNUSED pppoatm_init(void) 346{ 347 pppoatm_ioctl_hook = pppoatm_ioctl; 348 return 0; 349} 350 351static void __exit UNUSED pppoatm_exit(void) 352{ 353 pppoatm_ioctl_hook = NULL; 354} 355 356module_init(pppoatm_init); 357module_exit(pppoatm_exit); 358 359MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>"); 360MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5"); 361MODULE_LICENSE("GPL"); 362