Commit | Line | Data |
---|---|---|
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 | ||
99824461 JP |
36 | #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__ |
37 | ||
1da177e4 | 38 | #include <linux/module.h> |
1da177e4 | 39 | #include <linux/init.h> |
a6b7a407 | 40 | #include <linux/interrupt.h> |
1da177e4 | 41 | #include <linux/skbuff.h> |
5a0e3ad6 | 42 | #include <linux/slab.h> |
1da177e4 LT |
43 | #include <linux/atm.h> |
44 | #include <linux/atmdev.h> | |
4fc268d2 | 45 | #include <linux/capability.h> |
1da177e4 LT |
46 | #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 | ||
1da177e4 LT |
53 | enum pppoatm_encaps { |
54 | e_autodetect = PPPOATM_ENCAPS_AUTODETECT, | |
55 | e_vc = PPPOATM_ENCAPS_VC, | |
56 | e_llc = PPPOATM_ENCAPS_LLC, | |
57 | }; | |
58 | ||
59 | struct 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 | */ | |
74 | static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 }; | |
75 | #define LLC_LEN (4) | |
76 | ||
77 | static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc) | |
78 | { | |
79 | return (struct pppoatm_vcc *) (atmvcc->user_back); | |
80 | } | |
81 | ||
82 | static 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 | */ | |
92 | static 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 | */ | |
102 | static 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 | */ | |
121 | static 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 */ | |
136 | static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb) | |
137 | { | |
138 | struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); | |
99824461 | 139 | pr_debug("\n"); |
1da177e4 | 140 | if (skb == NULL) { /* VCC was closed */ |
52240062 | 141 | pr_debug("removing ATMPPP VCC %p\n", pvcc); |
1da177e4 LT |
142 | 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 | } | |
99824461 JP |
172 | 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]); | |
1da177e4 LT |
175 | goto error; |
176 | case e_vc: | |
177 | break; | |
178 | } | |
179 | ppp_input(&pvcc->chan, skb); | |
180 | return; | |
d81219db JP |
181 | |
182 | error: | |
1da177e4 LT |
183 | 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 | |
197 | static 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; | |
99824461 | 201 | pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc); |
1da177e4 LT |
202 | 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); | |
d81219db JP |
215 | skb = n; |
216 | if (skb == NULL) | |
1da177e4 LT |
217 | 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: | |
52240062 | 227 | pr_debug("Trying to send without setting encaps!\n"); |
1da177e4 LT |
228 | 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; | |
99824461 JP |
234 | pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", |
235 | skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev); | |
1da177e4 LT |
236 | return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb) |
237 | ? DROP_PACKET : 1; | |
d81219db | 238 | nospace: |
1da177e4 LT |
239 | /* |
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 */ | |
250 | static 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 | ||
d7100da0 | 264 | static const struct ppp_channel_ops pppoatm_ops = { |
1da177e4 LT |
265 | .start_xmit = pppoatm_send, |
266 | .ioctl = pppoatm_devppp_ioctl, | |
267 | }; | |
268 | ||
269 | static 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; | |
0da974f4 | 284 | pvcc = kzalloc(sizeof(*pvcc), GFP_KERNEL); |
1da177e4 LT |
285 | if (pvcc == NULL) |
286 | return -ENOMEM; | |
1da177e4 LT |
287 | 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; | |
d81219db JP |
297 | err = ppp_register_channel(&pvcc->chan); |
298 | if (err != 0) { | |
1da177e4 LT |
299 | 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 | */ | |
313 | static 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 | ||
342 | static struct atm_ioctl pppoatm_ioctl_ops = { | |
343 | .owner = THIS_MODULE, | |
344 | .ioctl = pppoatm_ioctl, | |
345 | }; | |
346 | ||
347 | static int __init pppoatm_init(void) | |
348 | { | |
349 | register_atm_ioctl(&pppoatm_ioctl_ops); | |
350 | return 0; | |
351 | } | |
352 | ||
353 | static void __exit pppoatm_exit(void) | |
354 | { | |
355 | deregister_atm_ioctl(&pppoatm_ioctl_ops); | |
356 | } | |
357 | ||
358 | module_init(pppoatm_init); | |
359 | module_exit(pppoatm_exit); | |
360 | ||
361 | MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>"); | |
362 | MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5"); | |
363 | MODULE_LICENSE("GPL"); |