1 /* net/atm/pppoatm.c - RFC2364 PPP over ATM/AAL5 */
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 */
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.
14 * This driver provides the encapsulation and framing for sending
15 * and receiving PPP frames in ATM AAL5 PDUs.
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)
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
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>
50 #define DPRINTK(format, args...) \
51 printk(KERN_DEBUG "pppoatm: " format, ##args)
53 #define DPRINTK(format, args...)
57 e_autodetect
= PPPOATM_ENCAPS_AUTODETECT
,
58 e_vc
= PPPOATM_ENCAPS_VC
,
59 e_llc
= PPPOATM_ENCAPS_LLC
,
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
;
74 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
75 * ID (0xC021) used in autodetection
77 static const unsigned char pppllc
[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
80 static inline struct pppoatm_vcc
*atmvcc_to_pvcc(const struct atm_vcc
*atmvcc
)
82 return (struct pppoatm_vcc
*) (atmvcc
->user_back
);
85 static inline struct pppoatm_vcc
*chan_to_pvcc(const struct ppp_channel
*chan
)
87 return (struct pppoatm_vcc
*) (chan
->private);
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
95 static void pppoatm_wakeup_sender(unsigned long arg
)
97 ppp_output_wakeup((struct ppp_channel
*) arg
);
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
105 static void pppoatm_pop(struct atm_vcc
*atmvcc
, struct sk_buff
*skb
)
107 struct pppoatm_vcc
*pvcc
= atmvcc_to_pvcc(atmvcc
);
108 pvcc
->old_pop(atmvcc
, skb
);
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.
117 tasklet_schedule(&pvcc
->wakeup_tasklet
);
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
124 static void pppoatm_unassign_vcc(struct atm_vcc
*atmvcc
)
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
;
134 /* Gee, I hope we have the big kernel lock here... */
135 module_put(THIS_MODULE
);
138 /* Called when an AAL5 PDU comes in */
139 static void pppoatm_push(struct atm_vcc
*atmvcc
, struct sk_buff
*skb
)
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 */
149 atm_return(atmvcc
, skb
->truesize
);
150 switch (pvcc
->encaps
) {
152 if (skb
->len
< LLC_LEN
||
153 memcmp(skb
->data
, pppllc
, LLC_LEN
))
155 skb_pull(skb
, LLC_LEN
);
158 if (pvcc
->chan
.ppp
== NULL
) { /* Not bound yet! */
162 if (skb
->len
>= sizeof(pppllc
) &&
163 !memcmp(skb
->data
, pppllc
, sizeof(pppllc
))) {
164 pvcc
->encaps
= e_llc
;
165 skb_pull(skb
, LLC_LEN
);
168 if (skb
->len
>= (sizeof(pppllc
) - LLC_LEN
) &&
169 !memcmp(skb
->data
, &pppllc
[LLC_LEN
],
170 sizeof(pppllc
) - LLC_LEN
)) {
172 pvcc
->chan
.mtu
+= LLC_LEN
;
175 DPRINTK("(unit %d): Couldn't autodetect yet "
176 "(skb: %02X %02X %02X %02X %02X %02X)\n",
178 skb
->data
[0], skb
->data
[1], skb
->data
[2],
179 skb
->data
[3], skb
->data
[4], skb
->data
[5]);
184 ppp_input(&pvcc
->chan
, skb
);
188 ppp_input_error(&pvcc
->chan
, 0);
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.
200 #define DROP_PACKET 1
201 static int pppoatm_send(struct ppp_channel
*chan
, struct sk_buff
*skb
)
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 */
211 if (skb_headroom(skb
) < LLC_LEN
) {
213 n
= skb_realloc_headroom(skb
, LLC_LEN
);
215 !atm_may_send(pvcc
->atmvcc
, n
->truesize
)) {
220 if ((skb
= n
) == NULL
)
222 } else if (!atm_may_send(pvcc
->atmvcc
, skb
->truesize
))
224 memcpy(skb_push(skb
, LLC_LEN
), pppllc
, LLC_LEN
);
227 if (!atm_may_send(pvcc
->atmvcc
, skb
->truesize
))
231 DPRINTK("(unit %d): Trying to send without setting encaps!\n",
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
)
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
249 if ((pvcc
->flags
& SC_COMP_PROT
) && skb_headroom(skb
) > 0 &&
250 skb
->data
[-1] == '\0')
251 (void) skb_push(skb
, 1);
255 /* This handles ioctls sent to the /dev/ppp interface */
256 static int pppoatm_devppp_ioctl(struct ppp_channel
*chan
, unsigned int cmd
,
261 return put_user(chan_to_pvcc(chan
)->flags
, (int __user
*) arg
)
264 return get_user(chan_to_pvcc(chan
)->flags
, (int __user
*) arg
)
270 static /*const*/ struct ppp_channel_ops pppoatm_ops
= {
271 .start_xmit
= pppoatm_send
,
272 .ioctl
= pppoatm_devppp_ioctl
,
275 static int pppoatm_assign_vcc(struct atm_vcc
*atmvcc
, void __user
*arg
)
277 struct atm_backend_ppp be
;
278 struct pppoatm_vcc
*pvcc
;
281 * Each PPPoATM instance has its own tasklet - this is just a
282 * prototypical one used to initialize them
284 static const DECLARE_TASKLET(tasklet_proto
, pppoatm_wakeup_sender
, 0);
285 if (copy_from_user(&be
, arg
, sizeof be
))
287 if (be
.encaps
!= PPPOATM_ENCAPS_AUTODETECT
&&
288 be
.encaps
!= PPPOATM_ENCAPS_VC
&& be
.encaps
!= PPPOATM_ENCAPS_LLC
)
290 pvcc
= kmalloc(sizeof(*pvcc
), GFP_KERNEL
);
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) {
308 atmvcc
->user_back
= pvcc
;
309 atmvcc
->push
= pppoatm_push
;
310 atmvcc
->pop
= pppoatm_pop
;
311 __module_get(THIS_MODULE
);
316 * This handles ioctls actually performed on our vcc - we must return
317 * -ENOIOCTLCMD for any unrecognized ioctl
319 static int pppoatm_ioctl(struct socket
*sock
, unsigned int cmd
,
322 struct atm_vcc
*atmvcc
= ATM_SD(sock
);
323 void __user
*argp
= (void __user
*)arg
;
325 if (cmd
!= ATM_SETBACKEND
&& atmvcc
->push
!= pppoatm_push
)
328 case ATM_SETBACKEND
: {
330 if (get_user(b
, (atm_backend_t __user
*) argp
))
332 if (b
!= ATM_BACKEND_PPP
)
334 if (!capable(CAP_NET_ADMIN
))
336 return pppoatm_assign_vcc(atmvcc
, argp
);
339 return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc
)->
340 chan
), (int __user
*) argp
) ? -EFAULT
: 0;
342 return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc
)->
343 chan
), (int __user
*) argp
) ? -EFAULT
: 0;
348 static struct atm_ioctl pppoatm_ioctl_ops
= {
349 .owner
= THIS_MODULE
,
350 .ioctl
= pppoatm_ioctl
,
353 static int __init
pppoatm_init(void)
355 register_atm_ioctl(&pppoatm_ioctl_ops
);
359 static void __exit
pppoatm_exit(void)
361 deregister_atm_ioctl(&pppoatm_ioctl_ops
);
364 module_init(pppoatm_init
);
365 module_exit(pppoatm_exit
);
367 MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>");
368 MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5");
369 MODULE_LICENSE("GPL");