| /* 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/config.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" |
| |
| #if 0 |
| #define DPRINTK(format, args...) \ |
| printk(KERN_DEBUG "pppoatm: " format, ##args) |
| #else |
| #define DPRINTK(format, args...) |
| #endif |
| |
| 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); |
| DPRINTK("pppoatm push\n"); |
| if (skb == NULL) { /* VCC was closed */ |
| DPRINTK("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; |
| } |
| DPRINTK("(unit %d): Couldn't autodetect yet " |
| "(skb: %02X %02X %02X %02X %02X %02X)\n", |
| pvcc->chan.unit, |
| 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; |
| DPRINTK("(unit %d): pppoatm_send (skb=0x%p, vcc=0x%p)\n", |
| pvcc->chan.unit, 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: |
| DPRINTK("(unit %d): Trying to send without setting encaps!\n", |
| pvcc->chan.unit); |
| 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; |
| DPRINTK("(unit %d): atm_skb(%p)->vcc(%p)->dev(%p)\n", |
| pvcc->chan.unit, 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 = kmalloc(sizeof(*pvcc), GFP_KERNEL); |
| if (pvcc == NULL) |
| return -ENOMEM; |
| memset(pvcc, 0, sizeof(*pvcc)); |
| 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"); |