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