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/* 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");
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