net/atm/pppoatm.c - kernel/mindspeed - Git at Google

 /* 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
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/skbuff.h>
 #include <linux/slab.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("\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("(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);
 			skb = n;
 			if (skb == 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;
 	err = ppp_register_channel(&pvcc->chan);
 	if (err != 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");
	/* 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
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/skbuff.h>
	#include <linux/slab.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("\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("(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);
	skb = n;
	if (skb == 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;
	err = ppp_register_channel(&pvcc->chan);
	if (err != 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");