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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 11192 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | #include "common.h" |
48 | |
49 | #if 0 |
50 | #define DPRINTK(format, args...) \ |
51 | printk(KERN_DEBUG "pppoatm: " format, ##args) |
52 | #else |
53 | #define DPRINTK(format, args...) |
54 | #endif |
55 | |
56 | enum pppoatm_encaps { |
57 | e_autodetect = PPPOATM_ENCAPS_AUTODETECT, |
58 | e_vc = PPPOATM_ENCAPS_VC, |
59 | e_llc = PPPOATM_ENCAPS_LLC, |
60 | }; |
61 | |
62 | struct pppoatm_vcc { |
63 | struct atm_vcc *atmvcc; /* VCC descriptor */ |
64 | void (*old_push)(struct atm_vcc *, struct sk_buff *); |
65 | void (*old_pop)(struct atm_vcc *, struct sk_buff *); |
66 | /* keep old push/pop for detaching */ |
67 | enum pppoatm_encaps encaps; |
68 | int flags; /* SC_COMP_PROT - compress protocol */ |
69 | struct ppp_channel chan; /* interface to generic ppp layer */ |
70 | struct tasklet_struct wakeup_tasklet; |
71 | }; |
72 | |
73 | /* |
74 | * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol |
75 | * ID (0xC021) used in autodetection |
76 | */ |
77 | static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 }; |
78 | #define LLC_LEN (4) |
79 | |
80 | static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc) |
81 | { |
82 | return (struct pppoatm_vcc *) (atmvcc->user_back); |
83 | } |
84 | |
85 | static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan) |
86 | { |
87 | return (struct pppoatm_vcc *) (chan->private); |
88 | } |
89 | |
90 | /* |
91 | * We can't do this directly from our _pop handler, since the ppp code |
92 | * doesn't want to be called in interrupt context, so we do it from |
93 | * a tasklet |
94 | */ |
95 | static void pppoatm_wakeup_sender(unsigned long arg) |
96 | { |
97 | ppp_output_wakeup((struct ppp_channel *) arg); |
98 | } |
99 | |
100 | /* |
101 | * This gets called every time the ATM card has finished sending our |
102 | * skb. The ->old_pop will take care up normal atm flow control, |
103 | * but we also need to wake up the device if we blocked it |
104 | */ |
105 | static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb) |
106 | { |
107 | struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); |
108 | pvcc->old_pop(atmvcc, skb); |
109 | /* |
110 | * We don't really always want to do this since it's |
111 | * really inefficient - it would be much better if we could |
112 | * test if we had actually throttled the generic layer. |
113 | * Unfortunately then there would be a nasty SMP race where |
114 | * we could clear that flag just as we refuse another packet. |
115 | * For now we do the safe thing. |
116 | */ |
117 | tasklet_schedule(&pvcc->wakeup_tasklet); |
118 | } |
119 | |
120 | /* |
121 | * Unbind from PPP - currently we only do this when closing the socket, |
122 | * but we could put this into an ioctl if need be |
123 | */ |
124 | static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc) |
125 | { |
126 | struct pppoatm_vcc *pvcc; |
127 | pvcc = atmvcc_to_pvcc(atmvcc); |
128 | atmvcc->push = pvcc->old_push; |
129 | atmvcc->pop = pvcc->old_pop; |
130 | tasklet_kill(&pvcc->wakeup_tasklet); |
131 | ppp_unregister_channel(&pvcc->chan); |
132 | atmvcc->user_back = NULL; |
133 | kfree(pvcc); |
134 | /* Gee, I hope we have the big kernel lock here... */ |
135 | module_put(THIS_MODULE); |
136 | } |
137 | |
138 | /* Called when an AAL5 PDU comes in */ |
139 | static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb) |
140 | { |
141 | struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); |
142 | DPRINTK("pppoatm push\n"); |
143 | if (skb == NULL) { /* VCC was closed */ |
144 | DPRINTK("removing ATMPPP VCC %p\n", pvcc); |
145 | pppoatm_unassign_vcc(atmvcc); |
146 | atmvcc->push(atmvcc, NULL); /* Pass along bad news */ |
147 | return; |
148 | } |
149 | atm_return(atmvcc, skb->truesize); |
150 | switch (pvcc->encaps) { |
151 | case e_llc: |
152 | if (skb->len < LLC_LEN || |
153 | memcmp(skb->data, pppllc, LLC_LEN)) |
154 | goto error; |
155 | skb_pull(skb, LLC_LEN); |
156 | break; |
157 | case e_autodetect: |
158 | if (pvcc->chan.ppp == NULL) { /* Not bound yet! */ |
159 | kfree_skb(skb); |
160 | return; |
161 | } |
162 | if (skb->len >= sizeof(pppllc) && |
163 | !memcmp(skb->data, pppllc, sizeof(pppllc))) { |
164 | pvcc->encaps = e_llc; |
165 | skb_pull(skb, LLC_LEN); |
166 | break; |
167 | } |
168 | if (skb->len >= (sizeof(pppllc) - LLC_LEN) && |
169 | !memcmp(skb->data, &pppllc[LLC_LEN], |
170 | sizeof(pppllc) - LLC_LEN)) { |
171 | pvcc->encaps = e_vc; |
172 | pvcc->chan.mtu += LLC_LEN; |
173 | break; |
174 | } |
175 | DPRINTK("(unit %d): Couldn't autodetect yet " |
176 | "(skb: %02X %02X %02X %02X %02X %02X)\n", |
177 | pvcc->chan.unit, |
178 | skb->data[0], skb->data[1], skb->data[2], |
179 | skb->data[3], skb->data[4], skb->data[5]); |
180 | goto error; |
181 | case e_vc: |
182 | break; |
183 | } |
184 | ppp_input(&pvcc->chan, skb); |
185 | return; |
186 | error: |
187 | kfree_skb(skb); |
188 | ppp_input_error(&pvcc->chan, 0); |
189 | } |
190 | |
191 | /* |
192 | * Called by the ppp_generic.c to send a packet - returns true if packet |
193 | * was accepted. If we return false, then it's our job to call |
194 | * ppp_output_wakeup(chan) when we're feeling more up to it. |
195 | * Note that in the ENOMEM case (as opposed to the !atm_may_send case) |
196 | * we should really drop the packet, but the generic layer doesn't |
197 | * support this yet. We just return 'DROP_PACKET' which we actually define |
198 | * as success, just to be clear what we're really doing. |
199 | */ |
200 | #define DROP_PACKET 1 |
201 | static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb) |
202 | { |
203 | struct pppoatm_vcc *pvcc = chan_to_pvcc(chan); |
204 | ATM_SKB(skb)->vcc = pvcc->atmvcc; |
205 | DPRINTK("(unit %d): pppoatm_send (skb=0x%p, vcc=0x%p)\n", |
206 | pvcc->chan.unit, skb, pvcc->atmvcc); |
207 | if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT)) |
208 | (void) skb_pull(skb, 1); |
209 | switch (pvcc->encaps) { /* LLC encapsulation needed */ |
210 | case e_llc: |
211 | if (skb_headroom(skb) < LLC_LEN) { |
212 | struct sk_buff *n; |
213 | n = skb_realloc_headroom(skb, LLC_LEN); |
214 | if (n != NULL && |
215 | !atm_may_send(pvcc->atmvcc, n->truesize)) { |
216 | kfree_skb(n); |
217 | goto nospace; |
218 | } |
219 | kfree_skb(skb); |
220 | if ((skb = n) == NULL) |
221 | return DROP_PACKET; |
222 | } else if (!atm_may_send(pvcc->atmvcc, skb->truesize)) |
223 | goto nospace; |
224 | memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN); |
225 | break; |
226 | case e_vc: |
227 | if (!atm_may_send(pvcc->atmvcc, skb->truesize)) |
228 | goto nospace; |
229 | break; |
230 | case e_autodetect: |
231 | DPRINTK("(unit %d): Trying to send without setting encaps!\n", |
232 | pvcc->chan.unit); |
233 | kfree_skb(skb); |
234 | return 1; |
235 | } |
236 | |
237 | atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc); |
238 | ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options; |
239 | DPRINTK("(unit %d): atm_skb(%p)->vcc(%p)->dev(%p)\n", |
240 | pvcc->chan.unit, skb, ATM_SKB(skb)->vcc, |
241 | ATM_SKB(skb)->vcc->dev); |
242 | return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb) |
243 | ? DROP_PACKET : 1; |
244 | nospace: |
245 | /* |
246 | * We don't have space to send this SKB now, but we might have |
247 | * already applied SC_COMP_PROT compression, so may need to undo |
248 | */ |
249 | if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 && |
250 | skb->data[-1] == '\0') |
251 | (void) skb_push(skb, 1); |
252 | return 0; |
253 | } |
254 | |
255 | /* This handles ioctls sent to the /dev/ppp interface */ |
256 | static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd, |
257 | unsigned long arg) |
258 | { |
259 | switch (cmd) { |
260 | case PPPIOCGFLAGS: |
261 | return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg) |
262 | ? -EFAULT : 0; |
263 | case PPPIOCSFLAGS: |
264 | return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg) |
265 | ? -EFAULT : 0; |
266 | } |
267 | return -ENOTTY; |
268 | } |
269 | |
270 | static /*const*/ struct ppp_channel_ops pppoatm_ops = { |
271 | .start_xmit = pppoatm_send, |
272 | .ioctl = pppoatm_devppp_ioctl, |
273 | }; |
274 | |
275 | static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg) |
276 | { |
277 | struct atm_backend_ppp be; |
278 | struct pppoatm_vcc *pvcc; |
279 | int err; |
280 | /* |
281 | * Each PPPoATM instance has its own tasklet - this is just a |
282 | * prototypical one used to initialize them |
283 | */ |
284 | static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0); |
285 | if (copy_from_user(&be, arg, sizeof be)) |
286 | return -EFAULT; |
287 | if (be.encaps != PPPOATM_ENCAPS_AUTODETECT && |
288 | be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC) |
289 | return -EINVAL; |
290 | pvcc = kmalloc(sizeof(*pvcc), GFP_KERNEL); |
291 | if (pvcc == NULL) |
292 | return -ENOMEM; |
293 | memset(pvcc, 0, sizeof(*pvcc)); |
294 | pvcc->atmvcc = atmvcc; |
295 | pvcc->old_push = atmvcc->push; |
296 | pvcc->old_pop = atmvcc->pop; |
297 | pvcc->encaps = (enum pppoatm_encaps) be.encaps; |
298 | pvcc->chan.private = pvcc; |
299 | pvcc->chan.ops = &pppoatm_ops; |
300 | pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN - |
301 | (be.encaps == e_vc ? 0 : LLC_LEN); |
302 | pvcc->wakeup_tasklet = tasklet_proto; |
303 | pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan; |
304 | if ((err = ppp_register_channel(&pvcc->chan)) != 0) { |
305 | kfree(pvcc); |
306 | return err; |
307 | } |
308 | atmvcc->user_back = pvcc; |
309 | atmvcc->push = pppoatm_push; |
310 | atmvcc->pop = pppoatm_pop; |
311 | __module_get(THIS_MODULE); |
312 | return 0; |
313 | } |
314 | |
315 | /* |
316 | * This handles ioctls actually performed on our vcc - we must return |
317 | * -ENOIOCTLCMD for any unrecognized ioctl |
318 | */ |
319 | static int pppoatm_ioctl(struct socket *sock, unsigned int cmd, |
320 | unsigned long arg) |
321 | { |
322 | struct atm_vcc *atmvcc = ATM_SD(sock); |
323 | void __user *argp = (void __user *)arg; |
324 | |
325 | if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push) |
326 | return -ENOIOCTLCMD; |
327 | switch (cmd) { |
328 | case ATM_SETBACKEND: { |
329 | atm_backend_t b; |
330 | if (get_user(b, (atm_backend_t __user *) argp)) |
331 | return -EFAULT; |
332 | if (b != ATM_BACKEND_PPP) |
333 | return -ENOIOCTLCMD; |
334 | if (!capable(CAP_NET_ADMIN)) |
335 | return -EPERM; |
336 | return pppoatm_assign_vcc(atmvcc, argp); |
337 | } |
338 | case PPPIOCGCHAN: |
339 | return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)-> |
340 | chan), (int __user *) argp) ? -EFAULT : 0; |
341 | case PPPIOCGUNIT: |
342 | return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)-> |
343 | chan), (int __user *) argp) ? -EFAULT : 0; |
344 | } |
345 | return -ENOIOCTLCMD; |
346 | } |
347 | |
348 | static struct atm_ioctl pppoatm_ioctl_ops = { |
349 | .owner = THIS_MODULE, |
350 | .ioctl = pppoatm_ioctl, |
351 | }; |
352 | |
353 | static int __init pppoatm_init(void) |
354 | { |
355 | register_atm_ioctl(&pppoatm_ioctl_ops); |
356 | return 0; |
357 | } |
358 | |
359 | static void __exit pppoatm_exit(void) |
360 | { |
361 | deregister_atm_ioctl(&pppoatm_ioctl_ops); |
362 | } |
363 | |
364 | module_init(pppoatm_init); |
365 | module_exit(pppoatm_exit); |
366 | |
367 | MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>"); |
368 | MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5"); |
369 | MODULE_LICENSE("GPL"); |