![Jorge Boncompte [DTI2]](/assets/img/avatar_default.png)
This function moves the implementation found in the clip and br2684 modules to common code, correctly unlinks the skb from the queue before pushing it and makes pppoatm use it. Signed-off-by: Jorge Boncompte [DTI2] <jorge@dti2.net> Signed-off-by: David S. Miller <davem@davemloft.net>
368 lines
11 KiB
C
368 lines
11 KiB
C
/* net/atm/pppoatm.c - RFC2364 PPP over ATM/AAL5 */
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/* Copyright 1999-2000 by Mitchell Blank Jr */
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/* Based on clip.c; 1995-1999 by Werner Almesberger, EPFL LRC/ICA */
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/* And on ppp_async.c; Copyright 1999 Paul Mackerras */
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/* And help from Jens Axboe */
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/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* This driver provides the encapsulation and framing for sending
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* and receiving PPP frames in ATM AAL5 PDUs.
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*/
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/*
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* One shortcoming of this driver is that it does not comply with
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* section 8 of RFC2364 - we are supposed to detect a change
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* in encapsulation and immediately abort the connection (in order
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* to avoid a black-hole being created if our peer loses state
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* and changes encapsulation unilaterally. However, since the
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* ppp_generic layer actually does the decapsulation, we need
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* a way of notifying it when we _think_ there might be a problem)
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* There's two cases:
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* 1. LLC-encapsulation was missing when it was enabled. In
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* this case, we should tell the upper layer "tear down
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* this session if this skb looks ok to you"
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* 2. LLC-encapsulation was present when it was disabled. Then
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* we need to tell the upper layer "this packet may be
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* ok, but if its in error tear down the session"
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* These hooks are not yet available in ppp_generic
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/atm.h>
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#include <linux/atmdev.h>
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#include <linux/capability.h>
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#include <linux/ppp_defs.h>
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#include <linux/if_ppp.h>
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#include <linux/ppp_channel.h>
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#include <linux/atmppp.h>
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#include "common.h"
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enum pppoatm_encaps {
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e_autodetect = PPPOATM_ENCAPS_AUTODETECT,
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e_vc = PPPOATM_ENCAPS_VC,
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e_llc = PPPOATM_ENCAPS_LLC,
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};
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struct pppoatm_vcc {
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struct atm_vcc *atmvcc; /* VCC descriptor */
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void (*old_push)(struct atm_vcc *, struct sk_buff *);
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void (*old_pop)(struct atm_vcc *, struct sk_buff *);
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/* keep old push/pop for detaching */
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enum pppoatm_encaps encaps;
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int flags; /* SC_COMP_PROT - compress protocol */
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struct ppp_channel chan; /* interface to generic ppp layer */
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struct tasklet_struct wakeup_tasklet;
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};
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/*
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* Header used for LLC Encapsulated PPP (4 bytes) followed by the LCP protocol
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* ID (0xC021) used in autodetection
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*/
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static const unsigned char pppllc[6] = { 0xFE, 0xFE, 0x03, 0xCF, 0xC0, 0x21 };
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#define LLC_LEN (4)
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static inline struct pppoatm_vcc *atmvcc_to_pvcc(const struct atm_vcc *atmvcc)
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{
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return (struct pppoatm_vcc *) (atmvcc->user_back);
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}
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static inline struct pppoatm_vcc *chan_to_pvcc(const struct ppp_channel *chan)
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{
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return (struct pppoatm_vcc *) (chan->private);
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}
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/*
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* We can't do this directly from our _pop handler, since the ppp code
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* doesn't want to be called in interrupt context, so we do it from
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* a tasklet
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*/
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static void pppoatm_wakeup_sender(unsigned long arg)
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{
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ppp_output_wakeup((struct ppp_channel *) arg);
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}
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/*
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* This gets called every time the ATM card has finished sending our
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* skb. The ->old_pop will take care up normal atm flow control,
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* but we also need to wake up the device if we blocked it
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*/
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static void pppoatm_pop(struct atm_vcc *atmvcc, struct sk_buff *skb)
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{
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struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
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pvcc->old_pop(atmvcc, skb);
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/*
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* We don't really always want to do this since it's
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* really inefficient - it would be much better if we could
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* test if we had actually throttled the generic layer.
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* Unfortunately then there would be a nasty SMP race where
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* we could clear that flag just as we refuse another packet.
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* For now we do the safe thing.
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*/
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tasklet_schedule(&pvcc->wakeup_tasklet);
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}
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/*
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* Unbind from PPP - currently we only do this when closing the socket,
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* but we could put this into an ioctl if need be
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*/
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static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
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{
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struct pppoatm_vcc *pvcc;
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pvcc = atmvcc_to_pvcc(atmvcc);
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atmvcc->push = pvcc->old_push;
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atmvcc->pop = pvcc->old_pop;
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tasklet_kill(&pvcc->wakeup_tasklet);
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ppp_unregister_channel(&pvcc->chan);
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atmvcc->user_back = NULL;
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kfree(pvcc);
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/* Gee, I hope we have the big kernel lock here... */
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module_put(THIS_MODULE);
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}
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/* Called when an AAL5 PDU comes in */
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static void pppoatm_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
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{
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struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
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pr_debug("\n");
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if (skb == NULL) { /* VCC was closed */
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pr_debug("removing ATMPPP VCC %p\n", pvcc);
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pppoatm_unassign_vcc(atmvcc);
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atmvcc->push(atmvcc, NULL); /* Pass along bad news */
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return;
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}
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atm_return(atmvcc, skb->truesize);
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switch (pvcc->encaps) {
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case e_llc:
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if (skb->len < LLC_LEN ||
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memcmp(skb->data, pppllc, LLC_LEN))
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goto error;
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skb_pull(skb, LLC_LEN);
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break;
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case e_autodetect:
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if (pvcc->chan.ppp == NULL) { /* Not bound yet! */
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kfree_skb(skb);
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return;
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}
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if (skb->len >= sizeof(pppllc) &&
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!memcmp(skb->data, pppllc, sizeof(pppllc))) {
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pvcc->encaps = e_llc;
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skb_pull(skb, LLC_LEN);
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break;
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}
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if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&
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!memcmp(skb->data, &pppllc[LLC_LEN],
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sizeof(pppllc) - LLC_LEN)) {
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pvcc->encaps = e_vc;
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pvcc->chan.mtu += LLC_LEN;
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break;
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}
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pr_debug("Couldn't autodetect yet (skb: %02X %02X %02X %02X %02X %02X)\n",
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skb->data[0], skb->data[1], skb->data[2],
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skb->data[3], skb->data[4], skb->data[5]);
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goto error;
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case e_vc:
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break;
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}
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ppp_input(&pvcc->chan, skb);
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return;
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error:
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kfree_skb(skb);
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ppp_input_error(&pvcc->chan, 0);
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}
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/*
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* Called by the ppp_generic.c to send a packet - returns true if packet
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* was accepted. If we return false, then it's our job to call
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* ppp_output_wakeup(chan) when we're feeling more up to it.
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* Note that in the ENOMEM case (as opposed to the !atm_may_send case)
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* we should really drop the packet, but the generic layer doesn't
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* support this yet. We just return 'DROP_PACKET' which we actually define
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* as success, just to be clear what we're really doing.
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*/
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#define DROP_PACKET 1
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static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
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{
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struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);
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ATM_SKB(skb)->vcc = pvcc->atmvcc;
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pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);
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if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))
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(void) skb_pull(skb, 1);
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switch (pvcc->encaps) { /* LLC encapsulation needed */
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case e_llc:
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if (skb_headroom(skb) < LLC_LEN) {
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struct sk_buff *n;
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n = skb_realloc_headroom(skb, LLC_LEN);
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if (n != NULL &&
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!atm_may_send(pvcc->atmvcc, n->truesize)) {
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kfree_skb(n);
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goto nospace;
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}
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kfree_skb(skb);
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skb = n;
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if (skb == NULL)
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return DROP_PACKET;
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} else if (!atm_may_send(pvcc->atmvcc, skb->truesize))
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goto nospace;
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memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
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break;
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case e_vc:
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if (!atm_may_send(pvcc->atmvcc, skb->truesize))
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goto nospace;
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break;
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case e_autodetect:
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pr_debug("Trying to send without setting encaps!\n");
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kfree_skb(skb);
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return 1;
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}
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atomic_add(skb->truesize, &sk_atm(ATM_SKB(skb)->vcc)->sk_wmem_alloc);
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ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
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pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",
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skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);
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return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
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? DROP_PACKET : 1;
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nospace:
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/*
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* We don't have space to send this SKB now, but we might have
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* already applied SC_COMP_PROT compression, so may need to undo
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*/
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if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 &&
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skb->data[-1] == '\0')
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(void) skb_push(skb, 1);
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return 0;
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}
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/* This handles ioctls sent to the /dev/ppp interface */
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static int pppoatm_devppp_ioctl(struct ppp_channel *chan, unsigned int cmd,
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unsigned long arg)
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{
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switch (cmd) {
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case PPPIOCGFLAGS:
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return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
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? -EFAULT : 0;
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case PPPIOCSFLAGS:
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return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg)
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? -EFAULT : 0;
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}
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return -ENOTTY;
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}
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static const struct ppp_channel_ops pppoatm_ops = {
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.start_xmit = pppoatm_send,
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.ioctl = pppoatm_devppp_ioctl,
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};
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static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
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{
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struct atm_backend_ppp be;
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struct pppoatm_vcc *pvcc;
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int err;
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/*
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* Each PPPoATM instance has its own tasklet - this is just a
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* prototypical one used to initialize them
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*/
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static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0);
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if (copy_from_user(&be, arg, sizeof be))
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return -EFAULT;
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if (be.encaps != PPPOATM_ENCAPS_AUTODETECT &&
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be.encaps != PPPOATM_ENCAPS_VC && be.encaps != PPPOATM_ENCAPS_LLC)
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return -EINVAL;
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pvcc = kzalloc(sizeof(*pvcc), GFP_KERNEL);
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if (pvcc == NULL)
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return -ENOMEM;
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pvcc->atmvcc = atmvcc;
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pvcc->old_push = atmvcc->push;
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pvcc->old_pop = atmvcc->pop;
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pvcc->encaps = (enum pppoatm_encaps) be.encaps;
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pvcc->chan.private = pvcc;
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pvcc->chan.ops = &pppoatm_ops;
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pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -
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(be.encaps == e_vc ? 0 : LLC_LEN);
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pvcc->wakeup_tasklet = tasklet_proto;
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pvcc->wakeup_tasklet.data = (unsigned long) &pvcc->chan;
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err = ppp_register_channel(&pvcc->chan);
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if (err != 0) {
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kfree(pvcc);
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return err;
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}
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atmvcc->user_back = pvcc;
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atmvcc->push = pppoatm_push;
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atmvcc->pop = pppoatm_pop;
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__module_get(THIS_MODULE);
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/* re-process everything received between connection setup and
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backend setup */
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vcc_process_recv_queue(atmvcc);
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return 0;
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}
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/*
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* This handles ioctls actually performed on our vcc - we must return
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* -ENOIOCTLCMD for any unrecognized ioctl
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*/
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static int pppoatm_ioctl(struct socket *sock, unsigned int cmd,
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unsigned long arg)
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{
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struct atm_vcc *atmvcc = ATM_SD(sock);
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void __user *argp = (void __user *)arg;
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if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push)
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return -ENOIOCTLCMD;
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switch (cmd) {
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case ATM_SETBACKEND: {
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atm_backend_t b;
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if (get_user(b, (atm_backend_t __user *) argp))
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return -EFAULT;
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if (b != ATM_BACKEND_PPP)
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return -ENOIOCTLCMD;
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if (!capable(CAP_NET_ADMIN))
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return -EPERM;
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return pppoatm_assign_vcc(atmvcc, argp);
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}
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case PPPIOCGCHAN:
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return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)->
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chan), (int __user *) argp) ? -EFAULT : 0;
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case PPPIOCGUNIT:
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return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)->
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chan), (int __user *) argp) ? -EFAULT : 0;
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}
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return -ENOIOCTLCMD;
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}
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static struct atm_ioctl pppoatm_ioctl_ops = {
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.owner = THIS_MODULE,
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.ioctl = pppoatm_ioctl,
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};
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static int __init pppoatm_init(void)
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{
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register_atm_ioctl(&pppoatm_ioctl_ops);
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return 0;
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}
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static void __exit pppoatm_exit(void)
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{
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deregister_atm_ioctl(&pppoatm_ioctl_ops);
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}
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module_init(pppoatm_init);
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module_exit(pppoatm_exit);
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MODULE_AUTHOR("Mitchell Blank Jr <mitch@sfgoth.com>");
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MODULE_DESCRIPTION("RFC2364 PPP over ATM/AAL5");
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MODULE_LICENSE("GPL");
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