cregit-Linux how code gets into the kernel

Release 4.14 net/atm/pppoatm.c

Directory: net/atm
/* 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/ppp-ioctl.h>
#include <linux/ppp_channel.h>
#include <linux/atmppp.h>

#include "common.h"

enum pppoatm_encaps {

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 *);
void (*old_release_cb)(struct atm_vcc *);
struct module *old_owner;
					/* keep old push/pop for detaching */
enum pppoatm_encaps encaps;
atomic_t inflight;
unsigned long blocked;
int flags;			/* SC_COMP_PROT - compress protocol */
struct ppp_channel chan;	/* interface to generic ppp layer */
struct tasklet_struct wakeup_tasklet;

 * We want to allow two packets in the queue. The one that's currently in
 * flight, and *one* queued up ready for the ATM device to send immediately
 * from its TX done IRQ. We want to be able to use atomic_inc_not_zero(), so
 * inflight == -2 represents an empty queue, -1 one packet, and zero means
 * there are two packets in the queue.

#define NONE_INFLIGHT -2

#define BLOCKED 0

 * 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); }


Linus Torvalds27100.00%1100.00%

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


Linus Torvalds27100.00%1100.00%

/* * 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); }


Linus Torvalds20100.00%1100.00%

static void pppoatm_release_cb(struct atm_vcc *atmvcc) { struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc); /* * As in pppoatm_pop(), it's safe to clear the BLOCKED bit here because * the wakeup *can't* race with pppoatm_send(). They both hold the PPP * channel's ->downl lock. And the potential race with *setting* it, * which leads to the double-check dance in pppoatm_may_send(), doesn't * exist here. In the sock_owned_by_user() case in pppoatm_send(), we * set the BLOCKED bit while the socket is still locked. We know that * ->release_cb() can't be called until that's done. */ if (test_and_clear_bit(BLOCKED, &pvcc->blocked)) tasklet_schedule(&pvcc->wakeup_tasklet); if (pvcc->old_release_cb) pvcc->old_release_cb(atmvcc); }


David Woodhouse55100.00%2100.00%

/* * 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); atomic_dec(&pvcc->inflight); /* * We always used to run the wakeup tasklet unconditionally here, for * fear of race conditions where we clear the BLOCKED flag just as we * refuse another packet in pppoatm_send(). This was quite inefficient. * * In fact it's OK. The PPP core will only ever call pppoatm_send() * while holding the channel->downl lock. And ppp_output_wakeup() as * called by the tasklet will *also* grab that lock. So even if another * CPU is in pppoatm_send() right now, the tasklet isn't going to race * with it. The wakeup *will* happen after the other CPU is safely out * of pppoatm_send() again. * * So if the CPU in pppoatm_send() has already set the BLOCKED bit and * it about to return, that's fine. We trigger a wakeup which will * happen later. And if the CPU in pppoatm_send() *hasn't* set the * BLOCKED bit yet, that's fine too because of the double check in * pppoatm_may_send() which is commented there. */ if (test_and_clear_bit(BLOCKED, &pvcc->blocked)) tasklet_schedule(&pvcc->wakeup_tasklet); }


Linus Torvalds4367.19%150.00%
David Woodhouse2132.81%150.00%

/* * 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; atmvcc->release_cb = pvcc->old_release_cb; tasklet_kill(&pvcc->wakeup_tasklet); ppp_unregister_channel(&pvcc->chan); atmvcc->user_back = NULL; kfree(pvcc); }


Linus Torvalds6587.84%133.33%
David Woodhouse810.81%133.33%
Luca Barbieri11.35%133.33%

/* 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 */ struct module *module; pr_debug("removing ATMPPP VCC %p\n", pvcc); module = pvcc->old_owner; pppoatm_unassign_vcc(atmvcc); atmvcc->push(atmvcc, NULL); /* Pass along bad news */ module_put(module); 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); }


Linus Torvalds30793.60%125.00%
Krzysztof Mazur164.88%125.00%
Stephen Hemminger30.91%125.00%
Joe Perches20.61%125.00%

static int pppoatm_may_send(struct pppoatm_vcc *pvcc, int size) { /* * It's not clear that we need to bother with using atm_may_send() * to check we don't exceed sk->sk_sndbuf. If userspace sets a * value of sk_sndbuf which is lower than the MTU, we're going to * block for ever. But the code always did that before we introduced * the packet count limit, so... */ if (atm_may_send(pvcc->atmvcc, size) && atomic_inc_not_zero_hint(&pvcc->inflight, NONE_INFLIGHT)) return 1; /* * We use test_and_set_bit() rather than set_bit() here because * we need to ensure there's a memory barrier after it. The bit * *must* be set before we do the atomic_inc() on pvcc->inflight. * There's no smp_mb__after_set_bit(), so it's this or abuse * smp_mb__after_atomic(). */ test_and_set_bit(BLOCKED, &pvcc->blocked); /* * We may have raced with pppoatm_pop(). If it ran for the * last packet in the queue, *just* before we set the BLOCKED * bit, then it might never run again and the channel could * remain permanently blocked. Cope with that race by checking * *again*. If it did run in that window, we'll have space on * the queue now and can return success. It's harmless to leave * the BLOCKED flag set, since it's only used as a trigger to * run the wakeup tasklet. Another wakeup will never hurt. * If pppoatm_pop() is running but hasn't got as far as making * space on the queue yet, then it hasn't checked the BLOCKED * flag yet either, so we're safe in that case too. It'll issue * an "immediate" wakeup... where "immediate" actually involves * taking the PPP channel's ->downl lock, which is held by the * code path that calls pppoatm_send(), and is thus going to * wait for us to finish. */ if (atm_may_send(pvcc->atmvcc, size) && atomic_inc_not_zero(&pvcc->inflight)) return 1; return 0; }


David Woodhouse7598.68%150.00%
Peter Zijlstra11.32%150.00%

/* * 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); struct atm_vcc *vcc; int ret; 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); vcc = ATM_SKB(skb)->vcc; bh_lock_sock(sk_atm(vcc)); if (sock_owned_by_user(sk_atm(vcc))) { /* * Needs to happen (and be flushed, hence test_and_) before we unlock * the socket. It needs to be seen by the time our ->release_cb gets * called. */ test_and_set_bit(BLOCKED, &pvcc->blocked); goto nospace; } if (test_bit(ATM_VF_RELEASED, &vcc->flags) || test_bit(ATM_VF_CLOSE, &vcc->flags) || !test_bit(ATM_VF_READY, &vcc->flags)) { bh_unlock_sock(sk_atm(vcc)); kfree_skb(skb); return DROP_PACKET; } 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 && !pppoatm_may_send(pvcc, n->truesize)) { kfree_skb(n); goto nospace; } consume_skb(skb); skb = n; if (skb == NULL) { bh_unlock_sock(sk_atm(vcc)); return DROP_PACKET; } } else if (!pppoatm_may_send(pvcc, skb->truesize)) goto nospace; memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN); break; case e_vc: if (!pppoatm_may_send(pvcc, skb->truesize)) goto nospace; break; case e_autodetect: bh_unlock_sock(sk_atm(vcc)); pr_debug("Trying to send without setting encaps!\n"); kfree_skb(skb); return 1; } refcount_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); ret = ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb) ? DROP_PACKET : 1; bh_unlock_sock(sk_atm(vcc)); return ret; nospace: bh_unlock_sock(sk_atm(vcc)); /* * 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; }


Linus Torvalds32967.14%17.69%
Krzysztof Mazur12826.12%215.38%
David Woodhouse163.27%215.38%
Joe Perches51.02%215.38%
Stephen Hemminger51.02%17.69%
Arnaldo Carvalho de Melo40.82%215.38%
Chas Williams10.20%17.69%
Elena Reshetova10.20%17.69%
Eric Dumazet10.20%17.69%

/* 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; }


Linus Torvalds7997.53%150.00%
Al Viro22.47%150.00%

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; /* Maximum is zero, so that we can use atomic_inc_not_zero() */ atomic_set(&pvcc->inflight, NONE_INFLIGHT); pvcc->old_push = atmvcc->push; pvcc->old_pop = atmvcc->pop; pvcc->old_owner = atmvcc->owner; pvcc->old_release_cb = atmvcc->release_cb; 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-> = (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; atmvcc->release_cb = pppoatm_release_cb; __module_get(THIS_MODULE); atmvcc->owner = THIS_MODULE; /* re-process everything received between connection setup and backend setup */ vcc_process_recv_queue(atmvcc); return 0; }


Linus Torvalds24380.73%110.00%
David Woodhouse258.31%220.00%
Krzysztof Mazur144.65%110.00%
Jorge Boncompte61.99%110.00%
Chas Williams51.66%220.00%
Joe Perches41.33%110.00%
Al Viro31.00%110.00%
Panagiotis Issaris10.33%110.00%

/* * 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; if (sock->state != SS_CONNECTED) return -EINVAL; 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; }


Linus Torvalds15277.95%125.00%
Al Viro199.74%125.00%
Chas Williams126.15%125.00%
Krzysztof Mazur126.15%125.00%

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; }


Linus Torvalds1372.22%133.33%
Chas Williams527.78%266.67%

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


Linus Torvalds1066.67%133.33%
Chas Williams533.33%266.67%

module_init(pppoatm_init); module_exit(pppoatm_exit); MODULE_AUTHOR("Mitchell Blank Jr <>"); MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5"); MODULE_LICENSE("GPL");

Overall Contributors

Linus Torvalds149573.65%13.03%
David Woodhouse22711.18%39.09%
Krzysztof Mazur1758.62%412.12%
Chas Williams482.36%618.18%
Al Viro241.18%13.03%
Joe Perches180.89%26.06%
Stephen Hemminger90.44%26.06%
Jorge Boncompte60.30%13.03%
Dave Jones50.25%13.03%
Arnaldo Carvalho de Melo40.20%26.06%
Rusty Russell40.20%13.03%
Tejun Heo30.15%13.03%
Alexey Dobriyan30.15%13.03%
Randy Dunlap30.15%13.03%
Panagiotis Issaris10.05%13.03%
Paul Mackerras10.05%13.03%
Eric Dumazet10.05%13.03%
Peter Zijlstra10.05%13.03%
Elena Reshetova10.05%13.03%
Luca Barbieri10.05%13.03%
Directory: net/atm
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.