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/*

Experimental ethernet netdevice using ATM AAL5 as underlying carrier

(RFC1483 obsoleted by RFC2684) for Linux 2.4

Author: Marcell GAL, 2000, XDSL Ltd, Hungary

*/

#include <linux/module.h>

#include <linux/config.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/list.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <linux/etherdevice.h>

#include <linux/rtnetlink.h>

#include <linux/ip.h>

#include <asm/uaccess.h>

#include <net/arp.h>

#include <linux/atm.h>

#include <linux/atmdev.h>

#include <linux/atmbr2684.h>

#include "common.h"

#include "ipcommon.h"

/*

 * Define this to use a version of the code which interacts with the higher

 * layers in a more intellegent way, by always reserving enough space for

 * our header at the begining of the packet.  However, there may still be

 * some problems with programs like tcpdump.  In 2.5 we'll sort out what

 * we need to do to get this perfect.  For now we just will copy the packet

 * if we need space for the header

 */

/* #define FASTER_VERSION */

#ifdef DEBUG

#define DPRINTK(format, args...) printk(KERN_DEBUG "br2684: " format, ##args)

#else

#define DPRINTK(format, args...)

#endif

#ifdef SKB_DEBUG

static void skb_debug(const struct sk_buff *skb)

{

#define NUM2PRINT 50

        char buf[NUM2PRINT * 3 + 1];    /* 3 chars per byte */

        int i = 0;

        for (i = 0; i < skb->len && i < NUM2PRINT; i++) {

                sprintf(buf + i * 3, "%2.2x ", 0xff & skb->data[i]);

        }

        printk(KERN_DEBUG "br2684: skb: %s\n", buf);

}

#else

#define skb_debug(skb)  do {} while (0)

#endif

static unsigned char llc_oui_pid_pad[] =

    { 0xAA, 0xAA, 0x03, 0x00, 0x80, 0xC2, 0x00, 0x07, 0x00, 0x00 };

#define PADLEN  (2)

enum br2684_encaps {

        e_vc  = BR2684_ENCAPS_VC,

        e_llc = BR2684_ENCAPS_LLC,

};

struct br2684_vcc {

        struct atm_vcc  *atmvcc;

        struct br2684_dev *brdev;

        /* keep old push,pop functions for chaining */

        void (*old_push)(struct atm_vcc *vcc,struct sk_buff *skb);

        /* void (*old_pop)(struct atm_vcc *vcc,struct sk_buff *skb); */

        enum br2684_encaps encaps;

        struct list_head brvccs;

#ifdef CONFIG_ATM_BR2684_IPFILTER

        struct br2684_filter filter;

#endif /* CONFIG_ATM_BR2684_IPFILTER */

#ifndef FASTER_VERSION

        unsigned copies_needed, copies_failed;

#endif /* FASTER_VERSION */

};

struct br2684_dev {

        struct net_device net_dev;

        struct list_head br2684_devs;

        int number;

        struct list_head brvccs; /* one device <=> one vcc (before xmas) */

        struct net_device_stats stats;

        int mac_was_set;

};

/*

 * This lock should be held for writing any time the list of devices or

 * their attached vcc's could be altered.  It should be held for reading

 * any time these are being queried.  Note that we sometimes need to

 * do read-locking under interrupt context, so write locking must block

 * the current CPU's interrupts

 */

static rwlock_t devs_lock = RW_LOCK_UNLOCKED;

static LIST_HEAD(br2684_devs);

static inline struct br2684_dev *BRPRIV(const struct net_device *net_dev)

{

        return (struct br2684_dev *) ((char *) (net_dev) -

            (unsigned long) (&((struct br2684_dev *) 0)->net_dev));

}

static inline struct br2684_dev *list_entry_brdev(const struct list_head *le)

{

        return list_entry(le, struct br2684_dev, br2684_devs);

}

static inline struct br2684_vcc *BR2684_VCC(const struct atm_vcc *atmvcc)

{

        return (struct br2684_vcc *) (atmvcc->user_back);

}

static inline struct br2684_vcc *list_entry_brvcc(const struct list_head *le)

{

        return list_entry(le, struct br2684_vcc, brvccs);

}

/* Caller should hold read_lock(&devs_lock) */

static struct br2684_dev *br2684_find_dev(const struct br2684_if_spec *s)

{

        struct list_head *lh;

        struct br2684_dev *brdev;

        switch (s->method) {

        case BR2684_FIND_BYNUM:

                list_for_each(lh, &br2684_devs) {

                        brdev = list_entry_brdev(lh);

                        if (brdev->number == s->spec.devnum)

                                return brdev;

                }

                break;

        case BR2684_FIND_BYIFNAME:

                list_for_each(lh, &br2684_devs) {

                        brdev = list_entry_brdev(lh);

                        if (!strncmp(brdev->net_dev.name, s->spec.ifname,

                            sizeof brdev->net_dev.name))

                                return brdev;

                }

                break;

        }

        return NULL;

}

/*

 * Send a packet out a particular vcc.  Not to useful right now, but paves

 * the way for multiple vcc's per itf.  Returns true if we can send,

 * otherwise false

 */

static int br2684_xmit_vcc(struct sk_buff *skb, struct br2684_dev *brdev,

        struct br2684_vcc *brvcc)

{

        struct atm_vcc *atmvcc;

#ifdef FASTER_VERSION

        if (brvcc->encaps == e_llc)

                memcpy(skb_push(skb, 8), llc_oui_pid_pad, 8);

        /* last 2 bytes of llc_oui_pid_pad are managed by header routines;

           yes, you got it: 8 + 2 = sizeof(llc_oui_pid_pad)

         */

#else

        int minheadroom = (brvcc->encaps == e_llc) ? 10 : 2;

        if (skb_headroom(skb) < minheadroom) {

                struct sk_buff *skb2 = skb_realloc_headroom(skb, minheadroom);

                brvcc->copies_needed++;

                dev_kfree_skb(skb);

                if (skb2 == NULL) {

                        brvcc->copies_failed++;

                        return 0;

                }

                skb = skb2;

        }

        skb_push(skb, minheadroom);

        if (brvcc->encaps == e_llc)

                memcpy(skb->data, llc_oui_pid_pad, 10);

        else

                memset(skb->data, 0, 2);

#endif /* FASTER_VERSION */

        skb_debug(skb);

        ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;

        DPRINTK("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, atmvcc, atmvcc->dev);

        if (!atm_may_send(atmvcc, skb->truesize)) {

                /* we free this here for now, because we cannot know in a higher

                        layer whether the skb point it supplied wasn't freed yet.

                        now, it always is.

                */

                dev_kfree_skb(skb);

                return 0;

                }

        atomic_add(skb->truesize, &atmvcc->sk->wmem_alloc);

        ATM_SKB(skb)->atm_options = atmvcc->atm_options;

        brdev->stats.tx_packets++;

        brdev->stats.tx_bytes += skb->len;

        atmvcc->send(atmvcc, skb);

        return 1;

}

static inline struct br2684_vcc *pick_outgoing_vcc(struct sk_buff *skb,

        struct br2684_dev *brdev)

{

        return list_empty(&brdev->brvccs) ? NULL :

            list_entry_brvcc(brdev->brvccs.next); /* 1 vcc/dev right now */

}

static int br2684_start_xmit(struct sk_buff *skb, struct net_device *dev)

{

        struct br2684_dev *brdev = BRPRIV(dev);

        struct br2684_vcc *brvcc;

        DPRINTK("br2684_start_xmit, skb->dst=%p\n", skb->dst);

        read_lock(&devs_lock);

        brvcc = pick_outgoing_vcc(skb, brdev);

        if (brvcc == NULL) {

                DPRINTK("no vcc attached to dev %s\n", dev->name);

                brdev->stats.tx_errors++;

                brdev->stats.tx_carrier_errors++;

                /* netif_stop_queue(dev); */

                dev_kfree_skb(skb);

                read_unlock(&devs_lock);

                return -EUNATCH;

        }

        if (!br2684_xmit_vcc(skb, brdev, brvcc)) {

                /*

                 * We should probably use netif_*_queue() here, but that

                 * involves added complication.  We need to walk before

                 * we can run

                 */

                /* don't free here! this pointer might be no longer valid!

                dev_kfree_skb(skb);

                */

                brdev->stats.tx_errors++;

                brdev->stats.tx_fifo_errors++;

        }

        read_unlock(&devs_lock);

        return 0;

}

static struct net_device_stats *br2684_get_stats(struct net_device *dev)

{

        DPRINTK("br2684_get_stats\n");

        return &BRPRIV(dev)->stats;

}

#ifdef FASTER_VERSION

/*

 * These mirror eth_header and eth_header_cache.  They are not usually

 * exported for use in modules, so we grab them from net_device

 * after ether_setup() is done with it.  Bit of a hack.

 */

static int (*my_eth_header)(struct sk_buff *, struct net_device *,

        unsigned short, void *, void *, unsigned);

static int (*my_eth_header_cache)(struct neighbour *, struct hh_cache *);

static int

br2684_header(struct sk_buff *skb, struct net_device *dev,

              unsigned short type, void *daddr, void *saddr, unsigned len)

{

        u16 *pad_before_eth;

        int t = my_eth_header(skb, dev, type, daddr, saddr, len);

        if (t > 0) {

                pad_before_eth = (u16 *) skb_push(skb, 2);

                *pad_before_eth = 0;

                return dev->hard_header_len;    /* or return 16; ? */

        } else

                return t;

}

static int

br2684_header_cache(struct neighbour *neigh, struct hh_cache *hh)

{

/* hh_data is 16 bytes long. if encaps is ether-llc we need 24, so

xmit will add the additional header part in that case */

        u16 *pad_before_eth = (u16 *)(hh->hh_data);

        int t = my_eth_header_cache(neigh, hh);

        DPRINTK("br2684_header_cache, neigh=%p, hh_cache=%p\n", neigh, hh);

        if (t < 0)

                return t;

        else {

                *pad_before_eth = 0;

                hh->hh_len = PADLEN + ETH_HLEN;

        }

        return 0;

}

/*

 * This is similar to eth_type_trans, which cannot be used because of

 * our dev->hard_header_len

 */

static inline unsigned short br_type_trans(struct sk_buff *skb,

                                               struct net_device *dev)

{

        struct ethhdr *eth;

        unsigned char *rawp;

        eth = skb->mac.ethernet;

        if (*eth->h_dest & 1) {

                if (memcmp(eth->h_dest, dev->broadcast, ETH_ALEN) == 0)

                        skb->pkt_type = PACKET_BROADCAST;

                else

                        skb->pkt_type = PACKET_MULTICAST;

        }

        else if (memcmp(eth->h_dest, dev->dev_addr, ETH_ALEN))

                skb->pkt_type = PACKET_OTHERHOST;

        if (ntohs(eth->h_proto) >= 1536)

                return eth->h_proto;

        rawp = skb->data;

        /*

         * This is a magic hack to spot IPX packets. Older Novell breaks

         * the protocol design and runs IPX over 802.3 without an 802.2 LLC

         * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This

         * won't work for fault tolerant netware but does for the rest.

         */

        if (*(unsigned short *) rawp == 0xFFFF)

                return htons(ETH_P_802_3);

        /*

         * Real 802.2 LLC

         */

        return htons(ETH_P_802_2);

}

#endif /* FASTER_VERSION */

/*

 * We remember when the MAC gets set, so we don't override it later with

 * the ESI of the ATM card of the first VC

 */

static int (*my_eth_mac_addr)(struct net_device *, void *);

static int br2684_mac_addr(struct net_device *dev, void *p)

{

        int err = my_eth_mac_addr(dev, p);

        if (!err)

                BRPRIV(dev)->mac_was_set = 1;

        return err;

}

#ifdef CONFIG_ATM_BR2684_IPFILTER

/* this IOCTL is experimental. */

static int br2684_setfilt(struct atm_vcc *atmvcc, unsigned long arg)

{

        struct br2684_vcc *brvcc;

        struct br2684_filter_set fs;

        if (copy_from_user(&fs, (void *) arg, sizeof fs))

                return -EFAULT;

        if (fs.ifspec.method != BR2684_FIND_BYNOTHING) {

                /*

                 * This is really a per-vcc thing, but we can also search

                 * by device

                 */

                struct br2684_dev *brdev;

                read_lock(&devs_lock);

                brdev = br2684_find_dev(&fs.ifspec);

                if (brdev == NULL || list_empty(&brdev->brvccs) ||

                    brdev->brvccs.next != brdev->brvccs.prev)  /* >1 VCC */

                        brvcc = NULL;

                else

                        brvcc = list_entry_brvcc(brdev->brvccs.next);

                read_unlock(&devs_lock);

                if (brvcc == NULL)

                        return -ESRCH;

        } else

                brvcc = BR2684_VCC(atmvcc);

        memcpy(&brvcc->filter, &fs.filter, sizeof(brvcc->filter));

        return 0;

}

/* Returns 1 if packet should be dropped */

static inline int

packet_fails_filter(u16 type, struct br2684_vcc *brvcc, struct sk_buff *skb)

{

        if (brvcc->filter.netmask == 0)

                return 0;                        /* no filter in place */

        if (type == __constant_htons(ETH_P_IP) &&

            (((struct iphdr *) (skb->data))->daddr & brvcc->filter.

             netmask) == brvcc->filter.prefix)

                return 0;

        if (type == __constant_htons(ETH_P_ARP))

                return 0;

        /* TODO: we should probably filter ARPs too.. don't want to have

         *   them returning values that don't make sense, or is that ok?

         */

        return 1;               /* drop */

}

#endif /* CONFIG_ATM_BR2684_IPFILTER */

static void br2684_close_vcc(struct br2684_vcc *brvcc)

{

        DPRINTK("removing VCC %p from dev %p\n", brvcc, brvcc->brdev);

        write_lock_irq(&devs_lock);

        list_del(&brvcc->brvccs);

        write_unlock_irq(&devs_lock);

        brvcc->atmvcc->user_back = NULL;        /* what about vcc->recvq ??? */

        brvcc->old_push(brvcc->atmvcc, NULL);   /* pass on the bad news */

        kfree(brvcc);

        MOD_DEC_USE_COUNT;

}

/* when AAL5 PDU comes in: */

static void br2684_push(struct atm_vcc *atmvcc, struct sk_buff *skb)

{

        struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);

        struct br2684_dev *brdev = brvcc->brdev;

        int plen = sizeof(llc_oui_pid_pad) + ETH_HLEN;

        DPRINTK("br2684_push\n");

        if (skb == NULL) {      /* skb==NULL means VCC is being destroyed */

                br2684_close_vcc(brvcc);

                if (list_empty(&brdev->brvccs)) {

                        read_lock(&devs_lock);

                        list_del(&brdev->br2684_devs);

                        read_unlock(&devs_lock);

                        unregister_netdev(&brdev->net_dev);

                        kfree(brdev);

                }

                return;

        }

        skb_debug(skb);

        atm_return(atmvcc, skb->truesize);

        DPRINTK("skb from brdev %p\n", brdev);

        if (brvcc->encaps == e_llc) {

                /* let us waste some time for checking the encapsulation.

                   Note, that only 7 char is checked so frames with a valid FCS

                   are also accepted (but FCS is not checked of course) */

                if (memcmp(skb->data, llc_oui_pid_pad, 7)) {

                        brdev->stats.rx_errors++;

                        dev_kfree_skb(skb);

                        return;

                }

                /* Strip FCS if present */

                if (skb->len > 7 && skb->data[7] == 0x01)

                        __skb_trim(skb, skb->len - 4);

        } else {

                plen = PADLEN + ETH_HLEN;       /* pad, dstmac,srcmac, ethtype */

                /* first 2 chars should be 0 */

                if (*((u16 *) (skb->data)) != 0) {

                        brdev->stats.rx_errors++;

                        dev_kfree_skb(skb);

                        return;

                }

        }

        if (skb->len < plen) {

                brdev->stats.rx_errors++;

                dev_kfree_skb(skb);     /* dev_ not needed? */

                return;

        }

#ifdef FASTER_VERSION

        /* FIXME: tcpdump shows that pointer to mac header is 2 bytes earlier,

           than should be. What else should I set? */

        skb_pull(skb, plen);

        skb->mac.raw = ((char *) (skb->data)) - ETH_HLEN;

        skb->pkt_type = PACKET_HOST;

#ifdef CONFIG_BR2684_FAST_TRANS

        skb->protocol = ((u16 *) skb->data)[-1];

#else                           /* some protocols might require this: */

        skb->protocol = br_type_trans(skb, &brdev->net_dev);

#endif /* CONFIG_BR2684_FAST_TRANS */

#else

        skb_pull(skb, plen - ETH_HLEN);

        skb->protocol = eth_type_trans(skb, &brdev->net_dev);

#endif /* FASTER_VERSION */

#ifdef CONFIG_ATM_BR2684_IPFILTER

        if (packet_fails_filter(skb->protocol, brvcc, skb)) {

                brdev->stats.rx_dropped++;

                dev_kfree_skb(skb);

                return;

        }

#endif /* CONFIG_ATM_BR2684_IPFILTER */

        skb->dev = &brdev->net_dev;

        ATM_SKB(skb)->vcc = atmvcc;     /* needed ? */

        DPRINTK("received packet's protocol: %x\n", ntohs(skb->protocol));

        skb_debug(skb);

        if (!(brdev->net_dev.flags & IFF_UP)) { /* sigh, interface is down */

                brdev->stats.rx_dropped++;

                dev_kfree_skb(skb);

                return;

        }

        brdev->stats.rx_packets++;

        brdev->stats.rx_bytes += skb->len;

        memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));

        netif_rx(skb);

}

static int br2684_regvcc(struct atm_vcc *atmvcc, unsigned long arg)

{

/* assign a vcc to a dev

Note: we do not have explicit unassign, but look at _push()

*/

        int err;

        struct br2684_vcc *brvcc;

        struct sk_buff_head copy;

        struct sk_buff *skb;

        struct br2684_dev *brdev;

        struct atm_backend_br2684 be;

        MOD_INC_USE_COUNT;

        if (copy_from_user(&be, (void *) arg, sizeof be)) {

                MOD_DEC_USE_COUNT;

                return -EFAULT;

        }

        write_lock_irq(&devs_lock);

        brdev = br2684_find_dev(&be.ifspec);

        if (brdev == NULL) {

                printk(KERN_ERR

                    "br2684: tried to attach to non-existant device\n");

                err = -ENXIO;

                goto error;

        }

        if (atmvcc->push == NULL) {

                err = -EBADFD;

                goto error;

        }

        if (!list_empty(&brdev->brvccs)) {      /* Only 1 VCC/dev right now */

                err = -EEXIST;

                goto error;

        }

        if (be.fcs_in != BR2684_FCSIN_NO || be.fcs_out != BR2684_FCSOUT_NO ||

            be.fcs_auto || be.has_vpiid || be.send_padding || (be.encaps !=

            BR2684_ENCAPS_VC && be.encaps != BR2684_ENCAPS_LLC) ||

            be.min_size != 0) {

                err = -EINVAL;

                goto error;

        }

        brvcc = kmalloc(sizeof(struct br2684_vcc), GFP_KERNEL);

        if (!brvcc) {

                err = -ENOMEM;

                goto error;

        }

        memset(brvcc, 0, sizeof(struct br2684_vcc));

        DPRINTK("br2684_regvcc vcc=%p, encaps=%d, brvcc=%p\n", atmvcc, be.encaps,

                brvcc);

        if (list_empty(&brdev->brvccs) && !brdev->mac_was_set) {

                unsigned char *esi = atmvcc->dev->esi;

                if (esi[0] | esi[1] | esi[2] | esi[3] | esi[4] | esi[5])

                        memcpy(brdev->net_dev.dev_addr, esi,

                            brdev->net_dev.addr_len);

                else

                        brdev->net_dev.dev_addr[2] = 1;

        }

        list_add(&brvcc->brvccs, &brdev->brvccs);

        write_unlock_irq(&devs_lock);

        brvcc->brdev = brdev;

        brvcc->atmvcc = atmvcc;

        atmvcc->user_back = brvcc;

        brvcc->encaps = (enum br2684_encaps) be.encaps;

        brvcc->old_push = atmvcc->push;

        barrier();

        atmvcc->push = br2684_push;

        skb_queue_head_init(&copy);

        skb_migrate(&atmvcc->sk->receive_queue, &copy);

        while ((skb = skb_dequeue(&copy))) {

                BRPRIV(skb->dev)->stats.rx_bytes -= skb->len;

                BRPRIV(skb->dev)->stats.rx_packets--;

                br2684_push(atmvcc, skb);

        }

        return 0;

    error:

        write_unlock_irq(&devs_lock);

        MOD_DEC_USE_COUNT;

        return err;

}

static int br2684_create(unsigned long arg)

{

        int err;

        struct br2684_dev *brdev;

        struct atm_newif_br2684 ni;

        DPRINTK("br2684_create\n");

        /*

         * We track module use by vcc's NOT the devices they're on.  We're

         * protected here against module death by the kernel_lock, but if

         * we need to sleep we should make sure that the module doesn't

         * disappear under us.

         */

        MOD_INC_USE_COUNT;

        if (copy_from_user(&ni, (void *) arg, sizeof ni)) {

                MOD_DEC_USE_COUNT;

                return -EFAULT;

        }

        if (ni.media != BR2684_MEDIA_ETHERNET || ni.mtu != 1500) {

                MOD_DEC_USE_COUNT;

                return -EINVAL;

        }

        if ((brdev = kmalloc(sizeof(struct br2684_dev), GFP_KERNEL)) == NULL) {

                MOD_DEC_USE_COUNT;

                return -ENOMEM;

        }

        memset(brdev, 0, sizeof(struct br2684_dev));

        INIT_LIST_HEAD(&brdev->brvccs);

        write_lock_irq(&devs_lock);

        brdev->number = list_empty(&br2684_devs) ? 1 :

            list_entry_brdev(br2684_devs.prev)->number + 1;

        list_add_tail(&brdev->br2684_devs, &br2684_devs);

        write_unlock_irq(&devs_lock);

        if (ni.ifname[0] != '\0') {

                memcpy(brdev->net_dev.name, ni.ifname,

                    sizeof(brdev->net_dev.name));

                brdev->net_dev.name[sizeof(brdev->net_dev.name) - 1] = '\0';

        } else

                sprintf(brdev->net_dev.name, "nas%d", brdev->number);

        DPRINTK("registered netdev %s\n", brdev->net_dev.name);

        ether_setup(&brdev->net_dev);

        brdev->mac_was_set = 0;

#ifdef FASTER_VERSION

        my_eth_header = brdev->net_dev.hard_header;

        brdev->net_dev.hard_header = br2684_header;

        my_eth_header_cache = brdev->net_dev.hard_header_cache;

        brdev->net_dev.hard_header_cache = br2684_header_cache;

        brdev->net_dev.hard_header_len = sizeof(llc_oui_pid_pad) + ETH_HLEN;    /* 10 + 14 */

#endif

        my_eth_mac_addr = brdev->net_dev.set_mac_address;

        brdev->net_dev.set_mac_address = br2684_mac_addr;

        brdev->net_dev.hard_start_xmit = br2684_start_xmit;

        brdev->net_dev.get_stats = br2684_get_stats;

        /* open, stop, do_ioctl ? */

        err = register_netdev(&brdev->net_dev);

        MOD_DEC_USE_COUNT;

        if (err < 0) {

                printk(KERN_ERR "br2684_create: register_netdev failed\n");

                write_lock_irq(&devs_lock);

                list_del(&brdev->br2684_devs);

                write_unlock_irq(&devs_lock);