[linux-2.6-block.git] / net / atm / pppoatm.c

/* net/atm/pppoatm.c - RFC2364 PPP over ATM/AAL5 */

/* Copyright 1999-2000 by Mitchell Blank Jr */
/* Based on clip.c; 1995-1999 by Werner Almesberger, EPFL LRC/ICA */
/* And on ppp_async.c; Copyright 1999 Paul Mackerras */
/* And help from Jens Axboe */

/*
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 * This driver provides the encapsulation and framing for sending
 * and receiving PPP frames in ATM AAL5 PDUs.
 */

/*
 * One shortcoming of this driver is that it does not comply with
 * section 8 of RFC2364 - we are supposed to detect a change
 * in encapsulation and immediately abort the connection (in order
 * to avoid a black-hole being created if our peer loses state
 * and changes encapsulation unilaterally.  However, since the
 * ppp_generic layer actually does the decapsulation, we need
 * a way of notifying it when we _think_ there might be a problem)
 * There's two cases:
 *   1.	LLC-encapsulation was missing when it was enabled.  In
 *	this case, we should tell the upper layer "tear down
 *	this session if this skb looks ok to you"
 *   2.	LLC-encapsulation was present when it was disabled.  Then
 *	we need to tell the upper layer "this packet may be
 *	ok, but if its in error tear down the session"
 * These hooks are not yet available in ppp_generic
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/capability.h>
#include <linux/ppp_defs.h>
#include <linux/if_ppp.h>
#include <linux/ppp_channel.h>
#include <linux/atmppp.h>

#include "common.h"

enum pppoatm_encaps {
	e_autodetect = PPPOATM_ENCAPS_AUTODETECT,
	e_vc = PPPOATM_ENCAPS_VC,
	e_llc = PPPOATM_ENCAPS_LLC,
};

struct pppoatm_vcc {
	struct atm_vcc	*atmvcc;	/* VCC descriptor */
	void (*old_push)(struct atm_vcc *, struct sk_buff *);
	void (*old_pop)(struct atm_vcc *, struct sk_buff *);
					/* keep old push/pop for detaching */
	enum pppoatm_encaps encaps;
	int flags;			/* SC_COMP_PROT - compress protocol */
	struct ppp_channel chan;	/* interface to generic ppp layer */
	struct tasklet_struct wakeup_tasklet;
};

/*
 * Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
 * ID (0xC021) used in autodetection
 */
static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
#define LLC_LEN		(4)

static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc)
{
	return (struct pppoatm_vcc *) (atmvcc->user_back);
}

static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan)
{
	return (struct pppoatm_vcc *) (chan->private);
}

/*
 * We can't do this directly from our _pop handler, since the ppp code
 * doesn't want to be called in interrupt context, so we do it from
 * a tasklet
 */
static void pppoatm_wakeup_sender(unsigned long arg)
{
	ppp_output_wakeup((struct ppp_channel *) arg);
}

/*
 * This gets called every time the ATM card has finished sending our
 * skb.  The ->old_pop will take care up normal atm flow control,
 * but we also need to wake up the device if we blocked it
 */
static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb)
{
	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
	pvcc->old_pop(atmvcc, skb);
	/*
	 * We don't really always want to do this since it's
	 * really inefficient - it would be much better if we could
	 * test if we had actually throttled the generic layer.
	 * Unfortunately then there would be a nasty SMP race where
	 * we could clear that flag just as we refuse another packet.
	 * For now we do the safe thing.
	 */
	tasklet_schedule(&pvcc->wakeup_tasklet);
}

/*
 * Unbind from PPP - currently we only do this when closing the socket,
 * but we could put this into an ioctl if need be
 */
static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
{
	struct pppoatm_vcc *pvcc;
	pvcc = atmvcc_to_pvcc(atmvcc);
	atmvcc->push = pvcc->old_push;
	atmvcc->pop = pvcc->old_pop;
	tasklet_kill(&pvcc->wakeup_tasklet);
	ppp_unregister_channel(&pvcc->chan);
	atmvcc->user_back = NULL;
	kfree(pvcc);
	/* Gee, I hope we have the big kernel lock here... */
	module_put(THIS_MODULE);
}

/* Called when an AAL5 PDU comes in */
static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
{
	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
	pr_debug("pppoatm push\n");
	if (skb == NULL) {			/* VCC was closed */
		pr_debug("removing ATMPPP VCC %p\n", pvcc);
		pppoatm_unassign_vcc(atmvcc);
		atmvcc->push(atmvcc, NULL);	/* Pass along bad news */
		return;
	}
	atm_return(atmvcc, skb->truesize);
	switch (pvcc->encaps) {
	case e_llc:
		if (skb->len < LLC_LEN ||
		    memcmp(skb->data, pppllc, LLC_LEN))
			goto error;
		skb_pull(skb, LLC_LEN);
		break;
	case e_autodetect:
		if (pvcc->chan.ppp == NULL) {	/* Not bound yet! */
			kfree_skb(skb);
			return;
		}
		if (skb->len >= sizeof(pppllc) &&
		    !memcmp(skb->data, pppllc, sizeof(pppllc))) {
			pvcc->encaps = e_llc;
			skb_pull(skb, LLC_LEN);
			break;
		}
		if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&
		    !memcmp(skb->data, &pppllc[LLC_LEN],
		    sizeof(pppllc) - LLC_LEN)) {
			pvcc->encaps = e_vc;
			pvcc->chan.mtu += LLC_LEN;
			break;
		}
		pr_debug("Couldn't autodetect yet "
		    "(skb: %02X %02X %02X %02X %02X %02X)\n",
		    skb->data[0], skb->data[1], skb->data[2],
		    skb->data[3], skb->data[4], skb->data[5]);
		goto error;
	case e_vc:
		break;
	}
	ppp_input(&pvcc->chan, skb);
	return;
    error:
	kfree_skb(skb);
	ppp_input_error(&pvcc->chan, 0);
}

/*
 * Called by the ppp_generic.c to send a packet - returns true if packet
 * was accepted.  If we return false, then it's our job to call
 * ppp_output_wakeup(chan) when we're feeling more up to it.
 * Note that in the ENOMEM case (as opposed to the !atm_may_send case)
 * we should really drop the packet, but the generic layer doesn't
 * support this yet.  We just return 'DROP_PACKET' which we actually define
 * as success, just to be clear what we're really doing.
 */
#define DROP_PACKET 1
static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
{
	struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);
	ATM_SKB(skb)->vcc = pvcc->atmvcc;
	pr_debug("pppoatm_send (skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);
	if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))
		(void) skb_pull(skb, 1);
	switch (pvcc->encaps) {		/* LLC encapsulation needed */
	case e_llc:
		if (skb_headroom(skb) < LLC_LEN) {
			struct sk_buff *n;
			n = skb_realloc_headroom(skb, LLC_LEN);
			if (n != NULL &&
			    !atm_may_send(pvcc->atmvcc, n->truesize)) {
				kfree_skb(n);
				goto nospace;
			}
			kfree_skb(skb);
			if ((skb = n) == NULL)
				return DROP_PACKET;
		} else if (!atm_may_send(pvcc->atmvcc, skb->truesize))
			goto nospace;
		memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
		break;
	case e_vc:
		if (!atm_may_send(pvcc->atmvcc, skb->truesize))
			goto nospace;
		break;
	case e_autodetect:
		pr_debug("Trying to send without setting encaps!\n");
		kfree_skb(skb);
		return 1;
	}

	atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc);
	ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, ATM_SKB(skb)->vcc,
	    ATM_SKB(skb)->vcc->dev);
	return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
	    ? DROP_PACKET : 1;
    nospace:
	/*
	 * We don't have space to send this SKB now, but we might have
	 * already applied SC_COMP_PROT compression, so may need to undo
	 */
	if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 &&
	    skb->data[-1] == '\0')
		(void) skb_push(skb, 1);
	return 0;
}

/* This handles ioctls sent to the /dev/ppp interface */
static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
	unsigned long arg)
{
	switch (cmd) {
	case PPPIOCGFLAGS:
		return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
		    ? -EFAULT : 0;
	case PPPIOCSFLAGS:
		return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
		    ? -EFAULT : 0;
	}
	return -ENOTTY;
}

static /*const*/ struct ppp_channel_ops pppoatm_ops = {
	.start_xmit = pppoatm_send,
	.ioctl = pppoatm_devppp_ioctl,
};

static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
{
	struct atm_backend_ppp be;
	struct pppoatm_vcc *pvcc;
	int err;
	/*
	 * Each PPPoATM instance has its own tasklet - this is just a
	 * prototypical one used to initialize them
	 */
	static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0);
	if (copy_from_user(&be, arg, sizeof be))
		return -EFAULT;
	if (be.encaps != PPPOATM_ENCAPS_AUTODETECT &&
	    be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC)
		return -EINVAL;
	pvcc = kzalloc(sizeof(*pvcc), GFP_KERNEL);
	if (pvcc == NULL)
		return -ENOMEM;
	pvcc->atmvcc = atmvcc;
	pvcc->old_push = atmvcc->push;
	pvcc->old_pop = atmvcc->pop;
	pvcc->encaps = (enum pppoatm_encaps) be.encaps;
	pvcc->chan.private = pvcc;
	pvcc->chan.ops = &pppoatm_ops;
	pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -
	    (be.encaps == e_vc ? 0 : LLC_LEN);
	pvcc->wakeup_tasklet = tasklet_proto;
	pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan;
	if ((err = ppp_register_channel(&pvcc->chan)) != 0) {
		kfree(pvcc);
		return err;
	}
	atmvcc->user_back = pvcc;
	atmvcc->push = pppoatm_push;
	atmvcc->pop = pppoatm_pop;
	__module_get(THIS_MODULE);
	return 0;
}

/*
 * This handles ioctls actually performed on our vcc - we must return
 * -ENOIOCTLCMD for any unrecognized ioctl
 */
static int pppoatm_ioctl(struct socket *sock, unsigned int cmd,
	unsigned long arg)
{
	struct atm_vcc *atmvcc = ATM_SD(sock);
	void __user *argp = (void __user *)arg;

	if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push)
		return -ENOIOCTLCMD;
	switch (cmd) {
	case ATM_SETBACKEND: {
		atm_backend_t b;
		if (get_user(b, (atm_backend_t __user *) argp))
			return -EFAULT;
		if (b != ATM_BACKEND_PPP)
			return -ENOIOCTLCMD;
		if (!capable(CAP_NET_ADMIN))
			return -EPERM;
		return pppoatm_assign_vcc(atmvcc, argp);
		}
	case PPPIOCGCHAN:
		return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)->
		    chan), (int __user *) argp) ? -EFAULT : 0;
	case PPPIOCGUNIT:
		return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)->
		    chan), (int __user *) argp) ? -EFAULT : 0;
	}
	return -ENOIOCTLCMD;
}

static struct atm_ioctl pppoatm_ioctl_ops = {
	.owner	= THIS_MODULE,
	.ioctl	= pppoatm_ioctl,
};

static int __init pppoatm_init(void)
{
	register_atm_ioctl(&pppoatm_ioctl_ops);
	return 0;
}

static void __exit pppoatm_exit(void)
{
	deregister_atm_ioctl(&pppoatm_ioctl_ops);
}

module_init(pppoatm_init);
module_exit(pppoatm_exit);

MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>");
MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5");
MODULE_LICENSE("GPL");
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
	36	#include <linux/module.h>
1da177e4 LT	37	#include <linux/init.h>
	38	#include <linux/skbuff.h>
	39	#include <linux/atm.h>
	40	#include <linux/atmdev.h>
4fc268d2	41	#include <linux/capability.h>
1da177e4 LT	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
1da177e4 LT	49	enum pppoatm_encaps {
	50	e_autodetect = PPPOATM_ENCAPS_AUTODETECT,
	51	e_vc = PPPOATM_ENCAPS_VC,
	52	e_llc = PPPOATM_ENCAPS_LLC,
	53	};
	54
	55	struct pppoatm_vcc {
	56	struct atm_vcc atmvcc; / VCC descriptor */
	57	void (old_push)(struct atm_vcc , struct sk_buff *);
	58	void (old_pop)(struct atm_vcc , struct sk_buff *);
	59	/* keep old push/pop for detaching */
	60	enum pppoatm_encaps encaps;
	61	int flags; /* SC_COMP_PROT - compress protocol */
	62	struct ppp_channel chan; /* interface to generic ppp layer */
	63	struct tasklet_struct wakeup_tasklet;
	64	};
	65
	66	/*
	67	* Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
	68	* ID (0xC021) used in autodetection
	69	*/
	70	static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
	71	#define LLC_LEN (4)
	72
	73	static inline struct pppoatm_vcc atmvcc_to_pvcc(const struct atm_vcc atmvcc)
	74	{
	75	return (struct pppoatm_vcc *) (atmvcc->user_back);
	76	}
	77
	78	static inline struct pppoatm_vcc chan_to_pvcc(const struct ppp_channel chan)
	79	{
	80	return (struct pppoatm_vcc *) (chan->private);
	81	}
	82
	83	/*
	84	* We can't do this directly from our _pop handler, since the ppp code
	85	* doesn't want to be called in interrupt context, so we do it from
	86	* a tasklet
	87	*/
	88	static void pppoatm_wakeup_sender(unsigned long arg)
	89	{
	90	ppp_output_wakeup((struct ppp_channel *) arg);
	91	}
	92
	93	/*
	94	* This gets called every time the ATM card has finished sending our
	95	* skb. The ->old_pop will take care up normal atm flow control,
	96	* but we also need to wake up the device if we blocked it
	97	*/
	98	static void pppoatm_pop(struct atm_vcc atmvcc, struct sk_buff skb)
	99	{
	100	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
	101	pvcc->old_pop(atmvcc, skb);
	102	/*
	103	* We don't really always want to do this since it's
	104	* really inefficient - it would be much better if we could
	105	* test if we had actually throttled the generic layer.
	106	* Unfortunately then there would be a nasty SMP race where
	107	* we could clear that flag just as we refuse another packet.
	108	* For now we do the safe thing.
	109	*/
	110	tasklet_schedule(&pvcc->wakeup_tasklet);
	111	}
	112
113	/*
114	* Unbind from PPP - currently we only do this when closing the socket,
115	* but we could put this into an ioctl if need be
116	*/
117	static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
118	{
119	struct pppoatm_vcc *pvcc;
120	pvcc = atmvcc_to_pvcc(atmvcc);
121	atmvcc->push = pvcc->old_push;
122	atmvcc->pop = pvcc->old_pop;
123	tasklet_kill(&pvcc->wakeup_tasklet);
124	ppp_unregister_channel(&pvcc->chan);
125	atmvcc->user_back = NULL;
126	kfree(pvcc);
127	/* Gee, I hope we have the big kernel lock here... */
128	module_put(THIS_MODULE);
129	}
130
131	/* Called when an AAL5 PDU comes in */
132	static void pppoatm_push(struct atm_vcc atmvcc, struct sk_buff skb)
133	{
134	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
52240062	135	pr_debug("pppoatm push\n");
1da177e4	136	if (skb == NULL) { /* VCC was closed */
52240062	137	pr_debug("removing ATMPPP VCC %p\n", pvcc);
1da177e4 LT	138	pppoatm_unassign_vcc(atmvcc);
	139	atmvcc->push(atmvcc, NULL); /* Pass along bad news */
	140	return;
	141	}
	142	atm_return(atmvcc, skb->truesize);
	143	switch (pvcc->encaps) {
	144	case e_llc:
	145	if (skb->len < LLC_LEN \|\|
	146	memcmp(skb->data, pppllc, LLC_LEN))
	147	goto error;
	148	skb_pull(skb, LLC_LEN);
	149	break;
	150	case e_autodetect:
	151	if (pvcc->chan.ppp == NULL) { /* Not bound yet! */
	152	kfree_skb(skb);
	153	return;
	154	}
	155	if (skb->len >= sizeof(pppllc) &&
	156	!memcmp(skb->data, pppllc, sizeof(pppllc))) {
	157	pvcc->encaps = e_llc;
	158	skb_pull(skb, LLC_LEN);
	159	break;
	160	}
	161	if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&
	162	!memcmp(skb->data, &pppllc[LLC_LEN],
	163	sizeof(pppllc) - LLC_LEN)) {
	164	pvcc->encaps = e_vc;
	165	pvcc->chan.mtu += LLC_LEN;
	166	break;
	167	}
52240062	168	pr_debug("Couldn't autodetect yet "
1da177e4	169	"(skb: %02X %02X %02X %02X %02X %02X)\n",
1da177e4 LT	170	skb->data[0], skb->data[1], skb->data[2],
	171	skb->data[3], skb->data[4], skb->data[5]);
	172	goto error;
	173	case e_vc:
	174	break;
	175	}
	176	ppp_input(&pvcc->chan, skb);
	177	return;
	178	error:
	179	kfree_skb(skb);
	180	ppp_input_error(&pvcc->chan, 0);
	181	}
	182
	183	/*
	184	* Called by the ppp_generic.c to send a packet - returns true if packet
	185	* was accepted. If we return false, then it's our job to call
	186	* ppp_output_wakeup(chan) when we're feeling more up to it.
	187	* Note that in the ENOMEM case (as opposed to the !atm_may_send case)
	188	* we should really drop the packet, but the generic layer doesn't
	189	* support this yet. We just return 'DROP_PACKET' which we actually define
	190	* as success, just to be clear what we're really doing.
	191	*/
	192	#define DROP_PACKET 1
	193	static int pppoatm_send(struct ppp_channel chan, struct sk_buff skb)
	194	{
	195	struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);
	196	ATM_SKB(skb)->vcc = pvcc->atmvcc;
52240062	197	pr_debug("pppoatm_send (skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);
1da177e4 LT	198	if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))
	199	(void) skb_pull(skb, 1);
	200	switch (pvcc->encaps) { /* LLC encapsulation needed */
	201	case e_llc:
	202	if (skb_headroom(skb) < LLC_LEN) {
	203	struct sk_buff *n;
	204	n = skb_realloc_headroom(skb, LLC_LEN);
	205	if (n != NULL &&
	206	!atm_may_send(pvcc->atmvcc, n->truesize)) {
	207	kfree_skb(n);
	208	goto nospace;
	209	}
	210	kfree_skb(skb);
	211	if ((skb = n) == NULL)
	212	return DROP_PACKET;
	213	} else if (!atm_may_send(pvcc->atmvcc, skb->truesize))
	214	goto nospace;
	215	memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
	216	break;
	217	case e_vc:
	218	if (!atm_may_send(pvcc->atmvcc, skb->truesize))
	219	goto nospace;
	220	break;
	221	case e_autodetect:
52240062	222	pr_debug("Trying to send without setting encaps!\n");
1da177e4 LT	223	kfree_skb(skb);
	224	return 1;
	225	}
	226
	227	atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc);
	228	ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
52240062	229	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, ATM_SKB(skb)->vcc,
1da177e4 LT	230	ATM_SKB(skb)->vcc->dev);
	231	return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
	232	? DROP_PACKET : 1;
	233	nospace:
	234	/*
	235	* We don't have space to send this SKB now, but we might have
	236	* already applied SC_COMP_PROT compression, so may need to undo
	237	*/
	238	if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 &&
	239	skb->data[-1] == '\0')
	240	(void) skb_push(skb, 1);
	241	return 0;
	242	}
	243
	244	/* This handles ioctls sent to the /dev/ppp interface */
	245	static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
	246	unsigned long arg)
	247	{
	248	switch (cmd) {
	249	case PPPIOCGFLAGS:
	250	return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
	251	? -EFAULT : 0;
	252	case PPPIOCSFLAGS:
	253	return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
	254	? -EFAULT : 0;
	255	}
	256	return -ENOTTY;
	257	}
	258
	259	static /const/ struct ppp_channel_ops pppoatm_ops = {
	260	.start_xmit = pppoatm_send,
	261	.ioctl = pppoatm_devppp_ioctl,
	262	};
	263
	264	static int pppoatm_assign_vcc(struct atm_vcc atmvcc, void __user arg)
	265	{
	266	struct atm_backend_ppp be;
	267	struct pppoatm_vcc *pvcc;
	268	int err;
	269	/*
	270	* Each PPPoATM instance has its own tasklet - this is just a
	271	* prototypical one used to initialize them
	272	*/
	273	static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0);
	274	if (copy_from_user(&be, arg, sizeof be))
	275	return -EFAULT;
	276	if (be.encaps != PPPOATM_ENCAPS_AUTODETECT &&
	277	be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC)
	278	return -EINVAL;
0da974f4	279	pvcc = kzalloc(sizeof(*pvcc), GFP_KERNEL);
1da177e4 LT	280	if (pvcc == NULL)
1da177e4 LT	281	return -ENOMEM;
1da177e4 LT	282	pvcc->atmvcc = atmvcc;
	283	pvcc->old_push = atmvcc->push;
	284	pvcc->old_pop = atmvcc->pop;
	285	pvcc->encaps = (enum pppoatm_encaps) be.encaps;
	286	pvcc->chan.private = pvcc;
	287	pvcc->chan.ops = &pppoatm_ops;
	288	pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -
	289	(be.encaps == e_vc ? 0 : LLC_LEN);
	290	pvcc->wakeup_tasklet = tasklet_proto;
	291	pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan;
	292	if ((err = ppp_register_channel(&pvcc->chan)) != 0) {
	293	kfree(pvcc);
	294	return err;
	295	}
	296	atmvcc->user_back = pvcc;
	297	atmvcc->push = pppoatm_push;
	298	atmvcc->pop = pppoatm_pop;
	299	__module_get(THIS_MODULE);
	300	return 0;
	301	}
	302
	303	/*
	304	* This handles ioctls actually performed on our vcc - we must return
	305	* -ENOIOCTLCMD for any unrecognized ioctl
	306	*/
	307	static int pppoatm_ioctl(struct socket *sock, unsigned int cmd,
	308	unsigned long arg)
	309	{
	310	struct atm_vcc *atmvcc = ATM_SD(sock);
	311	void __user argp = (void __user )arg;
	312
	313	if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push)
	314	return -ENOIOCTLCMD;
	315	switch (cmd) {
	316	case ATM_SETBACKEND: {
	317	atm_backend_t b;
	318	if (get_user(b, (atm_backend_t __user *) argp))
	319	return -EFAULT;
	320	if (b != ATM_BACKEND_PPP)
	321	return -ENOIOCTLCMD;
	322	if (!capable(CAP_NET_ADMIN))
	323	return -EPERM;
	324	return pppoatm_assign_vcc(atmvcc, argp);
	325	}
	326	case PPPIOCGCHAN:
	327	return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)->
	328	chan), (int __user *) argp) ? -EFAULT : 0;
	329	case PPPIOCGUNIT:
	330	return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)->
	331	chan), (int __user *) argp) ? -EFAULT : 0;
	332	}
	333	return -ENOIOCTLCMD;
	334	}
	335
	336	static struct atm_ioctl pppoatm_ioctl_ops = {
	337	.owner = THIS_MODULE,
	338	.ioctl = pppoatm_ioctl,
	339	};
	340
	341	static int __init pppoatm_init(void)
	342	{
	343	register_atm_ioctl(&pppoatm_ioctl_ops);
	344	return 0;
	345	}
346
347	static void __exit pppoatm_exit(void)
348	{
349	deregister_atm_ioctl(&pppoatm_ioctl_ops);
350	}
351
352	module_init(pppoatm_init);
353	module_exit(pppoatm_exit);
354
355	MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>");
356	MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5");
357	MODULE_LICENSE("GPL");