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1da177e4 LT |
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> | |
4fc268d2 | 42 | #include <linux/capability.h> |
1da177e4 LT |
43 | #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 | ||
57 | enum pppoatm_encaps { | |
58 | e_autodetect = PPPOATM_ENCAPS_AUTODETECT, | |
59 | e_vc = PPPOATM_ENCAPS_VC, | |
60 | e_llc = PPPOATM_ENCAPS_LLC, | |
61 | }; | |
62 | ||
63 | struct 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 | */ | |
78 | static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 }; | |
79 | #define LLC_LEN (4) | |
80 | ||
81 | static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc) | |
82 | { | |
83 | return (struct pppoatm_vcc *) (atmvcc->user_back); | |
84 | } | |
85 | ||
86 | static 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 | */ | |
96 | static 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 | */ | |
106 | static 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 | */ | |
125 | static 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 */ | |
140 | static 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 | |
202 | static 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 */ | |
257 | static 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 | ||
271 | static /*const*/ struct ppp_channel_ops pppoatm_ops = { | |
272 | .start_xmit = pppoatm_send, | |
273 | .ioctl = pppoatm_devppp_ioctl, | |
274 | }; | |
275 | ||
276 | static 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 | */ | |
320 | static 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 | ||
349 | static struct atm_ioctl pppoatm_ioctl_ops = { | |
350 | .owner = THIS_MODULE, | |
351 | .ioctl = pppoatm_ioctl, | |
352 | }; | |
353 | ||
354 | static int __init pppoatm_init(void) | |
355 | { | |
356 | register_atm_ioctl(&pppoatm_ioctl_ops); | |
357 | return 0; | |
358 | } | |
359 | ||
360 | static void __exit pppoatm_exit(void) | |
361 | { | |
362 | deregister_atm_ioctl(&pppoatm_ioctl_ops); | |
363 | } | |
364 | ||
365 | module_init(pppoatm_init); | |
366 | module_exit(pppoatm_exit); | |
367 | ||
368 | MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>"); | |
369 | MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5"); | |
370 | MODULE_LICENSE("GPL"); |