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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>
Alexey Dobriyana6b7a402011-06-06 10:43:46 +000040#include <linux/interrupt.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070041#include <linux/skbuff.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090042#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043#include <linux/atm.h>
44#include <linux/atmdev.h>
Randy Dunlap4fc268d2006-01-11 12:17:47 -080045#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070046#include <linux/ppp_defs.h>
47#include <linux/if_ppp.h>
48#include <linux/ppp_channel.h>
49#include <linux/atmppp.h>
50
51#include "common.h"
52
Linus Torvalds1da177e2005-04-16 15:20:36 -070053enum pppoatm_encaps {
54 e_autodetect = PPPOATM_ENCAPS_AUTODETECT,
55 e_vc = PPPOATM_ENCAPS_VC,
56 e_llc = PPPOATM_ENCAPS_LLC,
57};
58
59struct pppoatm_vcc {
60 struct atm_vcc *atmvcc; /* VCC descriptor */
61 void (*old_push)(struct atm_vcc *, struct sk_buff *);
62 void (*old_pop)(struct atm_vcc *, struct sk_buff *);
63 /* keep old push/pop for detaching */
64 enum pppoatm_encaps encaps;
65 int flags; /* SC_COMP_PROT - compress protocol */
66 struct ppp_channel chan; /* interface to generic ppp layer */
67 struct tasklet_struct wakeup_tasklet;
68};
69
70/*
71 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
72 * ID (0xC021) used in autodetection
73 */
74static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
75#define LLC_LEN (4)
76
77static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc)
78{
79 return (struct pppoatm_vcc *) (atmvcc->user_back);
80}
81
82static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan)
83{
84 return (struct pppoatm_vcc *) (chan->private);
85}
86
87/*
88 * We can't do this directly from our _pop handler, since the ppp code
89 * doesn't want to be called in interrupt context, so we do it from
90 * a tasklet
91 */
92static void pppoatm_wakeup_sender(unsigned long arg)
93{
94 ppp_output_wakeup((struct ppp_channel *) arg);
95}
96
97/*
98 * This gets called every time the ATM card has finished sending our
99 * skb. The ->old_pop will take care up normal atm flow control,
100 * but we also need to wake up the device if we blocked it
101 */
102static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb)
103{
104 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
105 pvcc->old_pop(atmvcc, skb);
106 /*
107 * We don't really always want to do this since it's
108 * really inefficient - it would be much better if we could
109 * test if we had actually throttled the generic layer.
110 * Unfortunately then there would be a nasty SMP race where
111 * we could clear that flag just as we refuse another packet.
112 * For now we do the safe thing.
113 */
114 tasklet_schedule(&pvcc->wakeup_tasklet);
115}
116
117/*
118 * Unbind from PPP - currently we only do this when closing the socket,
119 * but we could put this into an ioctl if need be
120 */
121static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
122{
123 struct pppoatm_vcc *pvcc;
124 pvcc = atmvcc_to_pvcc(atmvcc);
125 atmvcc->push = pvcc->old_push;
126 atmvcc->pop = pvcc->old_pop;
127 tasklet_kill(&pvcc->wakeup_tasklet);
128 ppp_unregister_channel(&pvcc->chan);
129 atmvcc->user_back = NULL;
130 kfree(pvcc);
131 /* Gee, I hope we have the big kernel lock here... */
132 module_put(THIS_MODULE);
133}
134
135/* Called when an AAL5 PDU comes in */
136static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
137{
138 struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
Joe Perches99824462010-01-26 11:40:00 +0000139 pr_debug("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 if (skb == NULL) { /* VCC was closed */
Stephen Hemminger52240062007-08-28 15:22:09 -0700141 pr_debug("removing ATMPPP VCC %p\n", pvcc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 pppoatm_unassign_vcc(atmvcc);
143 atmvcc->push(atmvcc, NULL); /* Pass along bad news */
144 return;
145 }
146 atm_return(atmvcc, skb->truesize);
147 switch (pvcc->encaps) {
148 case e_llc:
149 if (skb->len < LLC_LEN ||
150 memcmp(skb->data, pppllc, LLC_LEN))
151 goto error;
152 skb_pull(skb, LLC_LEN);
153 break;
154 case e_autodetect:
155 if (pvcc->chan.ppp == NULL) { /* Not bound yet! */
156 kfree_skb(skb);
157 return;
158 }
159 if (skb->len >= sizeof(pppllc) &&
160 !memcmp(skb->data, pppllc, sizeof(pppllc))) {
161 pvcc->encaps = e_llc;
162 skb_pull(skb, LLC_LEN);
163 break;
164 }
165 if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&
166 !memcmp(skb->data, &pppllc[LLC_LEN],
167 sizeof(pppllc) - LLC_LEN)) {
168 pvcc->encaps = e_vc;
169 pvcc->chan.mtu += LLC_LEN;
170 break;
171 }
Joe Perches99824462010-01-26 11:40:00 +0000172 pr_debug("Couldn't autodetect yet (skb: %02X %02X %02X %02X %02X %02X)\n",
173 skb->data[0], skb->data[1], skb->data[2],
174 skb->data[3], skb->data[4], skb->data[5]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 goto error;
176 case e_vc:
177 break;
178 }
179 ppp_input(&pvcc->chan, skb);
180 return;
Joe Perchesd81219d2010-01-26 11:40:12 +0000181
182error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 kfree_skb(skb);
184 ppp_input_error(&pvcc->chan, 0);
185}
186
187/*
188 * Called by the ppp_generic.c to send a packet - returns true if packet
189 * was accepted. If we return false, then it's our job to call
190 * ppp_output_wakeup(chan) when we're feeling more up to it.
191 * Note that in the ENOMEM case (as opposed to the !atm_may_send case)
192 * we should really drop the packet, but the generic layer doesn't
193 * support this yet. We just return 'DROP_PACKET' which we actually define
194 * as success, just to be clear what we're really doing.
195 */
196#define DROP_PACKET 1
197static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
198{
199 struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);
200 ATM_SKB(skb)->vcc = pvcc->atmvcc;
Joe Perches99824462010-01-26 11:40:00 +0000201 pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 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);
Joe Perchesd81219d2010-01-26 11:40:12 +0000215 skb = n;
216 if (skb == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 return DROP_PACKET;
218 } else if (!atm_may_send(pvcc->atmvcc, skb->truesize))
219 goto nospace;
220 memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
221 break;
222 case e_vc:
223 if (!atm_may_send(pvcc->atmvcc, skb->truesize))
224 goto nospace;
225 break;
226 case e_autodetect:
Stephen Hemminger52240062007-08-28 15:22:09 -0700227 pr_debug("Trying to send without setting encaps!\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 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;
Joe Perches99824462010-01-26 11:40:00 +0000234 pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",
235 skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
237 ? DROP_PACKET : 1;
Joe Perchesd81219d2010-01-26 11:40:12 +0000238nospace:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 /*
240 * We don't have space to send this SKB now, but we might have
241 * already applied SC_COMP_PROT compression, so may need to undo
242 */
243 if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 &&
244 skb->data[-1] == '\0')
245 (void) skb_push(skb, 1);
246 return 0;
247}
248
249/* This handles ioctls sent to the /dev/ppp interface */
250static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
251 unsigned long arg)
252{
253 switch (cmd) {
254 case PPPIOCGFLAGS:
255 return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
256 ? -EFAULT : 0;
257 case PPPIOCSFLAGS:
258 return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
259 ? -EFAULT : 0;
260 }
261 return -ENOTTY;
262}
263
stephen hemmingerd7100da2010-08-04 07:34:36 +0000264static const struct ppp_channel_ops pppoatm_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 .start_xmit = pppoatm_send,
266 .ioctl = pppoatm_devppp_ioctl,
267};
268
269static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
270{
271 struct atm_backend_ppp be;
272 struct pppoatm_vcc *pvcc;
273 int err;
274 /*
275 * Each PPPoATM instance has its own tasklet - this is just a
276 * prototypical one used to initialize them
277 */
278 static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0);
279 if (copy_from_user(&be, arg, sizeof be))
280 return -EFAULT;
281 if (be.encaps != PPPOATM_ENCAPS_AUTODETECT &&
282 be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC)
283 return -EINVAL;
Panagiotis Issaris0da974f2006-07-21 14:51:30 -0700284 pvcc = kzalloc(sizeof(*pvcc), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 if (pvcc == NULL)
286 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 pvcc->atmvcc = atmvcc;
288 pvcc->old_push = atmvcc->push;
289 pvcc->old_pop = atmvcc->pop;
290 pvcc->encaps = (enum pppoatm_encaps) be.encaps;
291 pvcc->chan.private = pvcc;
292 pvcc->chan.ops = &pppoatm_ops;
293 pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -
294 (be.encaps == e_vc ? 0 : LLC_LEN);
295 pvcc->wakeup_tasklet = tasklet_proto;
296 pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan;
Joe Perchesd81219d2010-01-26 11:40:12 +0000297 err = ppp_register_channel(&pvcc->chan);
298 if (err != 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 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");