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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* 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>
Randy Dunlap4fc268d2006-01-11 12:17:47 -080042#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043#include <linux/ppp_defs.h>
44#include <linux/if_ppp.h>
45#include <linux/ppp_channel.h>
46#include <linux/atmppp.h>
47
48#include "common.h"
49
50#if 0
51#define DPRINTK(format, args...) \
52 printk(KERN_DEBUG "pppoatm: " format, ##args)
53#else
54#define DPRINTK(format, args...)
55#endif
56
57enum pppoatm_encaps {
58 e_autodetect = PPPOATM_ENCAPS_AUTODETECT,
59 e_vc = PPPOATM_ENCAPS_VC,
60 e_llc = PPPOATM_ENCAPS_LLC,
61};
62
63struct pppoatm_vcc {
64 struct atm_vcc *atmvcc; /* VCC descriptor */
65 void (*old_push)(struct atm_vcc *, struct sk_buff *);
66 void (*old_pop)(struct atm_vcc *, struct sk_buff *);
67 /* keep old push/pop for detaching */
68 enum pppoatm_encaps encaps;
69 int flags; /* SC_COMP_PROT - compress protocol */
70 struct ppp_channel chan; /* interface to generic ppp layer */
71 struct tasklet_struct wakeup_tasklet;
72};
73
74/*
75 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
76 * ID (0xC021) used in autodetection
77 */
78static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
79#define LLC_LEN (4)
80
81static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc)
82{
83 return (struct pppoatm_vcc *) (atmvcc->user_back);
84}
85
86static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan)
87{
88 return (struct pppoatm_vcc *) (chan->private);
89}
90
91/*
92 * We can't do this directly from our _pop handler, since the ppp code
93 * doesn't want to be called in interrupt context, so we do it from
94 * a tasklet
95 */
96static void pppoatm_wakeup_sender(unsigned long arg)
97{
98 ppp_output_wakeup((struct ppp_channel *) arg);
99}
100
101/*
102 * This gets called every time the ATM card has finished sending our
103 * skb. The ->old_pop will take care up normal atm flow control,
104 * but we also need to wake up the device if we blocked it
105 */
106static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb)
107{
108 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
109 pvcc->old_pop(atmvcc, skb);
110 /*
111 * We don't really always want to do this since it's
112 * really inefficient - it would be much better if we could
113 * test if we had actually throttled the generic layer.
114 * Unfortunately then there would be a nasty SMP race where
115 * we could clear that flag just as we refuse another packet.
116 * For now we do the safe thing.
117 */
118 tasklet_schedule(&pvcc->wakeup_tasklet);
119}
120
121/*
122 * Unbind from PPP - currently we only do this when closing the socket,
123 * but we could put this into an ioctl if need be
124 */
125static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
126{
127 struct pppoatm_vcc *pvcc;
128 pvcc = atmvcc_to_pvcc(atmvcc);
129 atmvcc->push = pvcc->old_push;
130 atmvcc->pop = pvcc->old_pop;
131 tasklet_kill(&pvcc->wakeup_tasklet);
132 ppp_unregister_channel(&pvcc->chan);
133 atmvcc->user_back = NULL;
134 kfree(pvcc);
135 /* Gee, I hope we have the big kernel lock here... */
136 module_put(THIS_MODULE);
137}
138
139/* Called when an AAL5 PDU comes in */
140static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
141{
142 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
143 DPRINTK("pppoatm push\n");
144 if (skb == NULL) { /* VCC was closed */
145 DPRINTK("removing ATMPPP VCC %p\n", pvcc);
146 pppoatm_unassign_vcc(atmvcc);
147 atmvcc->push(atmvcc, NULL); /* Pass along bad news */
148 return;
149 }
150 atm_return(atmvcc, skb->truesize);
151 switch (pvcc->encaps) {
152 case e_llc:
153 if (skb->len < LLC_LEN ||
154 memcmp(skb->data, pppllc, LLC_LEN))
155 goto error;
156 skb_pull(skb, LLC_LEN);
157 break;
158 case e_autodetect:
159 if (pvcc->chan.ppp == NULL) { /* Not bound yet! */
160 kfree_skb(skb);
161 return;
162 }
163 if (skb->len >= sizeof(pppllc) &&
164 !memcmp(skb->data, pppllc, sizeof(pppllc))) {
165 pvcc->encaps = e_llc;
166 skb_pull(skb, LLC_LEN);
167 break;
168 }
169 if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&
170 !memcmp(skb->data, &pppllc[LLC_LEN],
171 sizeof(pppllc) - LLC_LEN)) {
172 pvcc->encaps = e_vc;
173 pvcc->chan.mtu += LLC_LEN;
174 break;
175 }
176 DPRINTK("(unit %d): Couldn't autodetect yet "
177 "(skb: %02X %02X %02X %02X %02X %02X)\n",
178 pvcc->chan.unit,
179 skb->data[0], skb->data[1], skb->data[2],
180 skb->data[3], skb->data[4], skb->data[5]);
181 goto error;
182 case e_vc:
183 break;
184 }
185 ppp_input(&pvcc->chan, skb);
186 return;
187 error:
188 kfree_skb(skb);
189 ppp_input_error(&pvcc->chan, 0);
190}
191
192/*
193 * Called by the ppp_generic.c to send a packet - returns true if packet
194 * was accepted. If we return false, then it's our job to call
195 * ppp_output_wakeup(chan) when we're feeling more up to it.
196 * Note that in the ENOMEM case (as opposed to the !atm_may_send case)
197 * we should really drop the packet, but the generic layer doesn't
198 * support this yet. We just return 'DROP_PACKET' which we actually define
199 * as success, just to be clear what we're really doing.
200 */
201#define DROP_PACKET 1
202static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
203{
204 struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);
205 ATM_SKB(skb)->vcc = pvcc->atmvcc;
206 DPRINTK("(unit %d): pppoatm_send (skb=0x%p, vcc=0x%p)\n",
207 pvcc->chan.unit, skb, pvcc->atmvcc);
208 if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))
209 (void) skb_pull(skb, 1);
210 switch (pvcc->encaps) { /* LLC encapsulation needed */
211 case e_llc:
212 if (skb_headroom(skb) < LLC_LEN) {
213 struct sk_buff *n;
214 n = skb_realloc_headroom(skb, LLC_LEN);
215 if (n != NULL &&
216 !atm_may_send(pvcc->atmvcc, n->truesize)) {
217 kfree_skb(n);
218 goto nospace;
219 }
220 kfree_skb(skb);
221 if ((skb = n) == NULL)
222 return DROP_PACKET;
223 } else if (!atm_may_send(pvcc->atmvcc, skb->truesize))
224 goto nospace;
225 memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
226 break;
227 case e_vc:
228 if (!atm_may_send(pvcc->atmvcc, skb->truesize))
229 goto nospace;
230 break;
231 case e_autodetect:
232 DPRINTK("(unit %d): Trying to send without setting encaps!\n",
233 pvcc->chan.unit);
234 kfree_skb(skb);
235 return 1;
236 }
237
238 atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc);
239 ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
240 DPRINTK("(unit %d): atm_skb(%p)->vcc(%p)->dev(%p)\n",
241 pvcc->chan.unit, skb, ATM_SKB(skb)->vcc,
242 ATM_SKB(skb)->vcc->dev);
243 return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
244 ? DROP_PACKET : 1;
245 nospace:
246 /*
247 * We don't have space to send this SKB now, but we might have
248 * already applied SC_COMP_PROT compression, so may need to undo
249 */
250 if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 &&
251 skb->data[-1] == '\0')
252 (void) skb_push(skb, 1);
253 return 0;
254}
255
256/* This handles ioctls sent to the /dev/ppp interface */
257static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
258 unsigned long arg)
259{
260 switch (cmd) {
261 case PPPIOCGFLAGS:
262 return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
263 ? -EFAULT : 0;
264 case PPPIOCSFLAGS:
265 return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
266 ? -EFAULT : 0;
267 }
268 return -ENOTTY;
269}
270
271static /*const*/ struct ppp_channel_ops pppoatm_ops = {
272 .start_xmit = pppoatm_send,
273 .ioctl = pppoatm_devppp_ioctl,
274};
275
276static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
277{
278 struct atm_backend_ppp be;
279 struct pppoatm_vcc *pvcc;
280 int err;
281 /*
282 * Each PPPoATM instance has its own tasklet - this is just a
283 * prototypical one used to initialize them
284 */
285 static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0);
286 if (copy_from_user(&be, arg, sizeof be))
287 return -EFAULT;
288 if (be.encaps != PPPOATM_ENCAPS_AUTODETECT &&
289 be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC)
290 return -EINVAL;
291 pvcc = kmalloc(sizeof(*pvcc), GFP_KERNEL);
292 if (pvcc == NULL)
293 return -ENOMEM;
294 memset(pvcc, 0, sizeof(*pvcc));
295 pvcc->atmvcc = atmvcc;
296 pvcc->old_push = atmvcc->push;
297 pvcc->old_pop = atmvcc->pop;
298 pvcc->encaps = (enum pppoatm_encaps) be.encaps;
299 pvcc->chan.private = pvcc;
300 pvcc->chan.ops = &pppoatm_ops;
301 pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -
302 (be.encaps == e_vc ? 0 : LLC_LEN);
303 pvcc->wakeup_tasklet = tasklet_proto;
304 pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan;
305 if ((err = ppp_register_channel(&pvcc->chan)) != 0) {
306 kfree(pvcc);
307 return err;
308 }
309 atmvcc->user_back = pvcc;
310 atmvcc->push = pppoatm_push;
311 atmvcc->pop = pppoatm_pop;
312 __module_get(THIS_MODULE);
313 return 0;
314}
315
316/*
317 * This handles ioctls actually performed on our vcc - we must return
318 * -ENOIOCTLCMD for any unrecognized ioctl
319 */
320static int pppoatm_ioctl(struct socket *sock, unsigned int cmd,
321 unsigned long arg)
322{
323 struct atm_vcc *atmvcc = ATM_SD(sock);
324 void __user *argp = (void __user *)arg;
325
326 if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push)
327 return -ENOIOCTLCMD;
328 switch (cmd) {
329 case ATM_SETBACKEND: {
330 atm_backend_t b;
331 if (get_user(b, (atm_backend_t __user *) argp))
332 return -EFAULT;
333 if (b != ATM_BACKEND_PPP)
334 return -ENOIOCTLCMD;
335 if (!capable(CAP_NET_ADMIN))
336 return -EPERM;
337 return pppoatm_assign_vcc(atmvcc, argp);
338 }
339 case PPPIOCGCHAN:
340 return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)->
341 chan), (int __user *) argp) ? -EFAULT : 0;
342 case PPPIOCGUNIT:
343 return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)->
344 chan), (int __user *) argp) ? -EFAULT : 0;
345 }
346 return -ENOIOCTLCMD;
347}
348
349static struct atm_ioctl pppoatm_ioctl_ops = {
350 .owner = THIS_MODULE,
351 .ioctl = pppoatm_ioctl,
352};
353
354static int __init pppoatm_init(void)
355{
356 register_atm_ioctl(&pppoatm_ioctl_ops);
357 return 0;
358}
359
360static void __exit pppoatm_exit(void)
361{
362 deregister_atm_ioctl(&pppoatm_ioctl_ops);
363}
364
365module_init(pppoatm_init);
366module_exit(pppoatm_exit);
367
368MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>");
369MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5");
370MODULE_LICENSE("GPL");