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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
Joe Perches99824462010-01-26 11:40:00 +000036#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070039#include <linux/init.h>
40#include <linux/skbuff.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090041#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070042#include <linux/atm.h>
43#include <linux/atmdev.h>
Randy Dunlap4fc268d2006-01-11 12:17:47 -080044#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/ppp_defs.h>
46#include <linux/if_ppp.h>
47#include <linux/ppp_channel.h>
48#include <linux/atmppp.h>
49
50#include "common.h"
51
Linus Torvalds1da177e2005-04-16 15:20:36 -070052enum pppoatm_encaps {
53 e_autodetect = PPPOATM_ENCAPS_AUTODETECT,
54 e_vc = PPPOATM_ENCAPS_VC,
55 e_llc = PPPOATM_ENCAPS_LLC,
56};
57
58struct pppoatm_vcc {
59 struct atm_vcc *atmvcc; /* VCC descriptor */
60 void (*old_push)(struct atm_vcc *, struct sk_buff *);
61 void (*old_pop)(struct atm_vcc *, struct sk_buff *);
62 /* keep old push/pop for detaching */
63 enum pppoatm_encaps encaps;
64 int flags; /* SC_COMP_PROT - compress protocol */
65 struct ppp_channel chan; /* interface to generic ppp layer */
66 struct tasklet_struct wakeup_tasklet;
67};
68
69/*
70 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
71 * ID (0xC021) used in autodetection
72 */
73static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
74#define LLC_LEN (4)
75
76static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc)
77{
78 return (struct pppoatm_vcc *) (atmvcc->user_back);
79}
80
81static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan)
82{
83 return (struct pppoatm_vcc *) (chan->private);
84}
85
86/*
87 * We can't do this directly from our _pop handler, since the ppp code
88 * doesn't want to be called in interrupt context, so we do it from
89 * a tasklet
90 */
91static void pppoatm_wakeup_sender(unsigned long arg)
92{
93 ppp_output_wakeup((struct ppp_channel *) arg);
94}
95
96/*
97 * This gets called every time the ATM card has finished sending our
98 * skb. The ->old_pop will take care up normal atm flow control,
99 * but we also need to wake up the device if we blocked it
100 */
101static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb)
102{
103 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
104 pvcc->old_pop(atmvcc, skb);
105 /*
106 * We don't really always want to do this since it's
107 * really inefficient - it would be much better if we could
108 * test if we had actually throttled the generic layer.
109 * Unfortunately then there would be a nasty SMP race where
110 * we could clear that flag just as we refuse another packet.
111 * For now we do the safe thing.
112 */
113 tasklet_schedule(&pvcc->wakeup_tasklet);
114}
115
116/*
117 * Unbind from PPP - currently we only do this when closing the socket,
118 * but we could put this into an ioctl if need be
119 */
120static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
121{
122 struct pppoatm_vcc *pvcc;
123 pvcc = atmvcc_to_pvcc(atmvcc);
124 atmvcc->push = pvcc->old_push;
125 atmvcc->pop = pvcc->old_pop;
126 tasklet_kill(&pvcc->wakeup_tasklet);
127 ppp_unregister_channel(&pvcc->chan);
128 atmvcc->user_back = NULL;
129 kfree(pvcc);
130 /* Gee, I hope we have the big kernel lock here... */
131 module_put(THIS_MODULE);
132}
133
134/* Called when an AAL5 PDU comes in */
135static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
136{
137 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
Joe Perches99824462010-01-26 11:40:00 +0000138 pr_debug("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 if (skb == NULL) { /* VCC was closed */
Stephen Hemminger52240062007-08-28 15:22:09 -0700140 pr_debug("removing ATMPPP VCC %p\n", pvcc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 pppoatm_unassign_vcc(atmvcc);
142 atmvcc->push(atmvcc, NULL); /* Pass along bad news */
143 return;
144 }
145 atm_return(atmvcc, skb->truesize);
146 switch (pvcc->encaps) {
147 case e_llc:
148 if (skb->len < LLC_LEN ||
149 memcmp(skb->data, pppllc, LLC_LEN))
150 goto error;
151 skb_pull(skb, LLC_LEN);
152 break;
153 case e_autodetect:
154 if (pvcc->chan.ppp == NULL) { /* Not bound yet! */
155 kfree_skb(skb);
156 return;
157 }
158 if (skb->len >= sizeof(pppllc) &&
159 !memcmp(skb->data, pppllc, sizeof(pppllc))) {
160 pvcc->encaps = e_llc;
161 skb_pull(skb, LLC_LEN);
162 break;
163 }
164 if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&
165 !memcmp(skb->data, &pppllc[LLC_LEN],
166 sizeof(pppllc) - LLC_LEN)) {
167 pvcc->encaps = e_vc;
168 pvcc->chan.mtu += LLC_LEN;
169 break;
170 }
Joe Perches99824462010-01-26 11:40:00 +0000171 pr_debug("Couldn't autodetect yet (skb: %02X %02X %02X %02X %02X %02X)\n",
172 skb->data[0], skb->data[1], skb->data[2],
173 skb->data[3], skb->data[4], skb->data[5]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 goto error;
175 case e_vc:
176 break;
177 }
178 ppp_input(&pvcc->chan, skb);
179 return;
Joe Perchesd81219d2010-01-26 11:40:12 +0000180
181error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 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;
Joe Perches99824462010-01-26 11:40:00 +0000200 pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))
202 (void) skb_pull(skb, 1);
203 switch (pvcc->encaps) { /* LLC encapsulation needed */
204 case e_llc:
205 if (skb_headroom(skb) < LLC_LEN) {
206 struct sk_buff *n;
207 n = skb_realloc_headroom(skb, LLC_LEN);
208 if (n != NULL &&
209 !atm_may_send(pvcc->atmvcc, n->truesize)) {
210 kfree_skb(n);
211 goto nospace;
212 }
213 kfree_skb(skb);
Joe Perchesd81219d2010-01-26 11:40:12 +0000214 skb = n;
215 if (skb == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 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:
Stephen Hemminger52240062007-08-28 15:22:09 -0700226 pr_debug("Trying to send without setting encaps!\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 kfree_skb(skb);
228 return 1;
229 }
230
231 atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc);
232 ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
Joe Perches99824462010-01-26 11:40:00 +0000233 pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",
234 skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
236 ? DROP_PACKET : 1;
Joe Perchesd81219d2010-01-26 11:40:12 +0000237nospace:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 /*
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 __user *) arg)
255 ? -EFAULT : 0;
256 case PPPIOCSFLAGS:
257 return get_user(chan_to_pvcc(chan)->flags, (int __user *) 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, void __user *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, 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;
Panagiotis Issaris0da974f2006-07-21 14:51:30 -0700283 pvcc = kzalloc(sizeof(*pvcc), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 if (pvcc == NULL)
285 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 pvcc->atmvcc = atmvcc;
287 pvcc->old_push = atmvcc->push;
288 pvcc->old_pop = atmvcc->pop;
289 pvcc->encaps = (enum pppoatm_encaps) be.encaps;
290 pvcc->chan.private = pvcc;
291 pvcc->chan.ops = &pppoatm_ops;
292 pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -
293 (be.encaps == e_vc ? 0 : LLC_LEN);
294 pvcc->wakeup_tasklet = tasklet_proto;
295 pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan;
Joe Perchesd81219d2010-01-26 11:40:12 +0000296 err = ppp_register_channel(&pvcc->chan);
297 if (err != 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 kfree(pvcc);
299 return err;
300 }
301 atmvcc->user_back = pvcc;
302 atmvcc->push = pppoatm_push;
303 atmvcc->pop = pppoatm_pop;
304 __module_get(THIS_MODULE);
305 return 0;
306}
307
308/*
309 * This handles ioctls actually performed on our vcc - we must return
310 * -ENOIOCTLCMD for any unrecognized ioctl
311 */
312static int pppoatm_ioctl(struct socket *sock, unsigned int cmd,
313 unsigned long arg)
314{
315 struct atm_vcc *atmvcc = ATM_SD(sock);
316 void __user *argp = (void __user *)arg;
317
318 if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push)
319 return -ENOIOCTLCMD;
320 switch (cmd) {
321 case ATM_SETBACKEND: {
322 atm_backend_t b;
323 if (get_user(b, (atm_backend_t __user *) argp))
324 return -EFAULT;
325 if (b != ATM_BACKEND_PPP)
326 return -ENOIOCTLCMD;
327 if (!capable(CAP_NET_ADMIN))
328 return -EPERM;
329 return pppoatm_assign_vcc(atmvcc, argp);
330 }
331 case PPPIOCGCHAN:
332 return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)->
333 chan), (int __user *) argp) ? -EFAULT : 0;
334 case PPPIOCGUNIT:
335 return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)->
336 chan), (int __user *) argp) ? -EFAULT : 0;
337 }
338 return -ENOIOCTLCMD;
339}
340
341static struct atm_ioctl pppoatm_ioctl_ops = {
342 .owner = THIS_MODULE,
343 .ioctl = pppoatm_ioctl,
344};
345
346static int __init pppoatm_init(void)
347{
348 register_atm_ioctl(&pppoatm_ioctl_ops);
349 return 0;
350}
351
352static void __exit pppoatm_exit(void)
353{
354 deregister_atm_ioctl(&pppoatm_ioctl_ops);
355}
356
357module_init(pppoatm_init);
358module_exit(pppoatm_exit);
359
360MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>");
361MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5");
362MODULE_LICENSE("GPL");