1 files changed, 369 insertions, 0 deletions

diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
new file mode 100644
index 000000000000..58f4a2b5aebe
--- /dev/null
+++ b/net/atm/pppoatm.c
@@ -0,0 +1,369 @@
+/* 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/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");