// SPDX-License-Identifier: GPL-2.0-only
/*
 * Ethernet netdevice using ATM AAL5 as underlying carrier
 * (RFC1483 obsoleted by RFC2684) for Linux
 *
 * Authors: Marcell GAL, 2000, XDSL Ltd, Hungary
 *          Eric Kinzie, 2006-2007, US Naval Research Laboratory
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/module.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 <linux/uaccess.h>
#include <linux/slab.h>
#include <net/arp.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/capability.h>
#include <linux/seq_file.h>

#include <linux/atmbr2684.h>

#include "common.h"

static void skb_debug(const struct sk_buff *skb)
{
#ifdef SKB_DEBUG
#define NUM2PRINT 50
        print_hex_dump(KERN_DEBUG, "br2684: skb: ", DUMP_OFFSET,
                       16, 1, skb->data, min(NUM2PRINT, skb->len), true);
#endif
}

#define BR2684_ETHERTYPE_LEN    2
#define BR2684_PAD_LEN          2

#define LLC             0xaa, 0xaa, 0x03
#define SNAP_BRIDGED    0x00, 0x80, 0xc2
#define SNAP_ROUTED     0x00, 0x00, 0x00
#define PID_ETHERNET    0x00, 0x07
#define ETHERTYPE_IPV4  0x08, 0x00
#define ETHERTYPE_IPV6  0x86, 0xdd
#define PAD_BRIDGED     0x00, 0x00

static const unsigned char ethertype_ipv4[] = { ETHERTYPE_IPV4 };
static const unsigned char ethertype_ipv6[] = { ETHERTYPE_IPV6 };
static const unsigned char llc_oui_pid_pad[] =
                        { LLC, SNAP_BRIDGED, PID_ETHERNET, PAD_BRIDGED };
static const unsigned char pad[] = { PAD_BRIDGED };
static const unsigned char llc_oui_ipv4[] = { LLC, SNAP_ROUTED, ETHERTYPE_IPV4 };
static const unsigned char llc_oui_ipv6[] = { LLC, SNAP_ROUTED, ETHERTYPE_IPV6 };

enum br2684_encaps {
        e_vc = BR2684_ENCAPS_VC,
        e_llc = BR2684_ENCAPS_LLC,
};

struct br2684_vcc {
        struct atm_vcc *atmvcc;
        struct net_device *device;
        /* 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);
        void (*old_release_cb)(struct atm_vcc *vcc);
        struct module *old_owner;
        enum br2684_encaps encaps;
        struct list_head brvccs;
#ifdef CONFIG_ATM_BR2684_IPFILTER
        struct br2684_filter filter;
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        unsigned int copies_needed, copies_failed;
        atomic_t qspace;
};

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) */
        int mac_was_set;
        enum br2684_payload payload;
};

/*
 * 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 DEFINE_RWLOCK(devs_lock);

static LIST_HEAD(br2684_devs);

static inline struct br2684_dev *BRPRIV(const struct net_device *net_dev)
{
        return netdev_priv(net_dev);
}

static inline struct net_device *list_entry_brdev(const struct list_head *le)
{
        return list_entry(le, struct br2684_dev, br2684_devs)->net_dev;
}

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 net_device *br2684_find_dev(const struct br2684_if_spec *s)
{
        struct list_head *lh;
        struct net_device *net_dev;
        switch (s->method) {
        case BR2684_FIND_BYNUM:
                list_for_each(lh, &br2684_devs) {
                        net_dev = list_entry_brdev(lh);
                        if (BRPRIV(net_dev)->number == s->spec.devnum)
                                return net_dev;
                }
                break;
        case BR2684_FIND_BYIFNAME:
                list_for_each(lh, &br2684_devs) {
                        net_dev = list_entry_brdev(lh);
                        if (!strncmp(net_dev->name, s->spec.ifname, IFNAMSIZ))
                                return net_dev;
                }
                break;
        }
        return NULL;
}

static int atm_dev_event(struct notifier_block *this, unsigned long event,
                 void *arg)
{
        struct atm_dev *atm_dev = arg;
        struct list_head *lh;
        struct net_device *net_dev;
        struct br2684_vcc *brvcc;
        struct atm_vcc *atm_vcc;
        unsigned long flags;

        pr_debug("event=%ld dev=%p\n", event, atm_dev);

        read_lock_irqsave(&devs_lock, flags);
        list_for_each(lh, &br2684_devs) {
                net_dev = list_entry_brdev(lh);

                list_for_each_entry(brvcc, &BRPRIV(net_dev)->brvccs, brvccs) {
                        atm_vcc = brvcc->atmvcc;
                        if (atm_vcc && brvcc->atmvcc->dev == atm_dev) {

                                if (atm_vcc->dev->signal == ATM_PHY_SIG_LOST)
                                        netif_carrier_off(net_dev);
                                else
                                        netif_carrier_on(net_dev);

                        }
                }
        }
        read_unlock_irqrestore(&devs_lock, flags);

        return NOTIFY_DONE;
}

static struct notifier_block atm_dev_notifier = {
        .notifier_call = atm_dev_event,
};

/* chained vcc->pop function.  Check if we should wake the netif_queue */
static void br2684_pop(struct atm_vcc *vcc, struct sk_buff *skb)
{
        struct br2684_vcc *brvcc = BR2684_VCC(vcc);

        pr_debug("(vcc %p ; net_dev %p )\n", vcc, brvcc->device);
        brvcc->old_pop(vcc, skb);

        /* If the queue space just went up from zero, wake */
        if (atomic_inc_return(&brvcc->qspace) == 1)
                netif_wake_queue(brvcc->device);
}

/*
 * 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 net_device *dev,
                           struct br2684_vcc *brvcc)
{
        struct br2684_dev *brdev = BRPRIV(dev);
        struct atm_vcc *atmvcc;
        int minheadroom = (brvcc->encaps == e_llc) ?
                ((brdev->payload == p_bridged) ?
                        sizeof(llc_oui_pid_pad) : sizeof(llc_oui_ipv4)) :
                ((brdev->payload == p_bridged) ? BR2684_PAD_LEN : 0);

        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;
        }

        if (brvcc->encaps == e_llc) {
                if (brdev->payload == p_bridged) {
                        skb_push(skb, sizeof(llc_oui_pid_pad));
                        skb_copy_to_linear_data(skb, llc_oui_pid_pad,
                                                sizeof(llc_oui_pid_pad));
                } else if (brdev->payload == p_routed) {
                        unsigned short prot = ntohs(skb->protocol);

                        skb_push(skb, sizeof(llc_oui_ipv4));
                        switch (prot) {
                        case ETH_P_IP:
                                skb_copy_to_linear_data(skb, llc_oui_ipv4,
                                                        sizeof(llc_oui_ipv4));
                                break;
                        case ETH_P_IPV6:
                                skb_copy_to_linear_data(skb, llc_oui_ipv6,
                                                        sizeof(llc_oui_ipv6));
                                break;
                        default:
                                dev_kfree_skb(skb);
                                return 0;
                        }
                }
        } else { /* e_vc */
                if (brdev->payload == p_bridged) {
                        skb_push(skb, 2);
                        memset(skb->data, 0, 2);
                }
        }
        skb_debug(skb);

        ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;
        pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, atmvcc, atmvcc->dev);
        atm_account_tx(atmvcc, skb);
        dev->stats.tx_packets++;
        dev->stats.tx_bytes += skb->len;

        if (atomic_dec_return(&brvcc->qspace) < 1) {
                /* No more please! */
                netif_stop_queue(brvcc->device);
                /* We might have raced with br2684_pop() */
                if (unlikely(atomic_read(&brvcc->qspace) > 0))
                        netif_wake_queue(brvcc->device);
        }

        /* If this fails immediately, the skb will be freed and br2684_pop()
           will wake the queue if appropriate. Just return an error so that
           the stats are updated correctly */
        return !atmvcc->send(atmvcc, skb);
}

static void br2684_release_cb(struct atm_vcc *atmvcc)
{
        struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);

        if (atomic_read(&brvcc->qspace) > 0)
                netif_wake_queue(brvcc->device);

        if (brvcc->old_release_cb)
                brvcc->old_release_cb(atmvcc);
}

static inline struct br2684_vcc *pick_outgoing_vcc(const struct sk_buff *skb,
                                                   const struct br2684_dev *brdev)
{
        return list_empty(&brdev->brvccs) ? NULL : list_entry_brvcc(brdev->brvccs.next);        /* 1 vcc/dev right now */
}

static netdev_tx_t br2684_start_xmit(struct sk_buff *skb,
                                     struct net_device *dev)
{
        struct br2684_dev *brdev = BRPRIV(dev);
        struct br2684_vcc *brvcc;
        struct atm_vcc *atmvcc;
        netdev_tx_t ret = NETDEV_TX_OK;

        pr_debug("skb_dst(skb)=%p\n", skb_dst(skb));
        read_lock(&devs_lock);
        brvcc = pick_outgoing_vcc(skb, brdev);
        if (brvcc == NULL) {
                pr_debug("no vcc attached to dev %s\n", dev->name);
                dev->stats.tx_errors++;
                dev->stats.tx_carrier_errors++;
                /* netif_stop_queue(dev); */
                dev_kfree_skb(skb);
                goto out_devs;
        }
        atmvcc = brvcc->atmvcc;

        bh_lock_sock(sk_atm(atmvcc));

        if (test_bit(ATM_VF_RELEASED, &atmvcc->flags) ||
            test_bit(ATM_VF_CLOSE, &atmvcc->flags) ||
            !test_bit(ATM_VF_READY, &atmvcc->flags)) {
                dev->stats.tx_dropped++;
                dev_kfree_skb(skb);
                goto out;
        }

        if (sock_owned_by_user(sk_atm(atmvcc))) {
                netif_stop_queue(brvcc->device);
                ret = NETDEV_TX_BUSY;
                goto out;
        }

        if (!br2684_xmit_vcc(skb, dev, 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->stats.tx_errors++;
                dev->stats.tx_fifo_errors++;
        }
 out:
        bh_unlock_sock(sk_atm(atmvcc));
 out_devs:
        read_unlock(&devs_lock);
        return ret;
}

/*
 * 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 br2684_mac_addr(struct net_device *dev, void *p)
{
        int err = 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, void __user * arg)
{
        struct br2684_vcc *brvcc;
        struct br2684_filter_set fs;

        if (copy_from_user(&fs, 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 = BRPRIV(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(__be16 type, struct br2684_vcc *brvcc, struct sk_buff *skb)
{
        if (brvcc->filter.netmask == 0)
                return 0;       /* no filter in place */
        if (type == htons(ETH_P_IP) &&
            (((struct iphdr *)(skb->data))->daddr & brvcc->filter.
             netmask) == brvcc->filter.prefix)
                return 0;
        if (type == 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)
{
        pr_debug("removing VCC %p from dev %p\n", brvcc, brvcc->device);
        write_lock_irq(&devs_lock);
        list_del(&brvcc->brvccs);
        write_unlock_irq(&devs_lock);
        brvcc->atmvcc->user_back = NULL;        /* what about vcc->recvq ??? */
        brvcc->atmvcc->release_cb = brvcc->old_release_cb;
        brvcc->old_push(brvcc->atmvcc, NULL);   /* pass on the bad news */
        module_put(brvcc->old_owner);
        kfree(brvcc);
}

/* 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 net_device *net_dev = brvcc->device;
        struct br2684_dev *brdev = BRPRIV(net_dev);

        pr_debug("\n");

        if (unlikely(skb == NULL)) {
                /* skb==NULL means VCC is being destroyed */
                br2684_close_vcc(brvcc);
                if (list_empty(&brdev->brvccs)) {
                        write_lock_irq(&devs_lock);
                        list_del(&brdev->br2684_devs);
                        write_unlock_irq(&devs_lock);
                        unregister_netdev(net_dev);
                        free_netdev(net_dev);
                }
                return;
        }

        skb_debug(skb);
        atm_return(atmvcc, skb->truesize);
        pr_debug("skb from brdev %p\n", brdev);
        if (brvcc->encaps == e_llc) {

                if (skb->len > 7 && skb->data[7] == 0x01)
                        __skb_trim(skb, skb->len - 4);

                /* accept packets that have "ipv[46]" in the snap header */
                if ((skb->len >= (sizeof(llc_oui_ipv4))) &&
                    (memcmp(skb->data, llc_oui_ipv4,
                            sizeof(llc_oui_ipv4) - BR2684_ETHERTYPE_LEN) == 0)) {
                        if (memcmp(skb->data + 6, ethertype_ipv6,
                                   sizeof(ethertype_ipv6)) == 0)
                                skb->protocol = htons(ETH_P_IPV6);
                        else if (memcmp(skb->data + 6, ethertype_ipv4,
                                        sizeof(ethertype_ipv4)) == 0)
                                skb->protocol = htons(ETH_P_IP);
                        else
                                goto error;
                        skb_pull(skb, sizeof(llc_oui_ipv4));
                        skb_reset_network_header(skb);
                        skb->pkt_type = PACKET_HOST;
                /*
                 * 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).
                 */
                } else if ((skb->len >= sizeof(llc_oui_pid_pad)) &&
                           (memcmp(skb->data, llc_oui_pid_pad, 7) == 0)) {
                        skb_pull(skb, sizeof(llc_oui_pid_pad));
                        skb->protocol = eth_type_trans(skb, net_dev);
                } else
                        goto error;

        } else { /* e_vc */
                if (brdev->payload == p_routed) {
                        struct iphdr *iph;

                        skb_reset_network_header(skb);
                        iph = ip_hdr(skb);
                        if (iph->version == 4)
                                skb->protocol = htons(ETH_P_IP);
                        else if (iph->version == 6)
                                skb->protocol = htons(ETH_P_IPV6);
                        else
                                goto error;
                        skb->pkt_type = PACKET_HOST;
                } else { /* p_bridged */
                        /* first 2 chars should be 0 */
                        if (memcmp(skb->data, pad, BR2684_PAD_LEN) != 0)
                                goto error;
                        skb_pull(skb, BR2684_PAD_LEN);
                        skb->protocol = eth_type_trans(skb, net_dev);
                }
        }

#ifdef CONFIG_ATM_BR2684_IPFILTER
        if (unlikely(packet_fails_filter(skb->protocol, brvcc, skb)))
                goto dropped;
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        skb->dev = net_dev;
        ATM_SKB(skb)->vcc = atmvcc;     /* needed ? */
        pr_debug("received packet's protocol: %x\n", ntohs(skb->protocol));
        skb_debug(skb);
        /* sigh, interface is down? */
        if (unlikely(!(net_dev->flags & IFF_UP)))
                goto dropped;
        net_dev->stats.rx_packets++;
        net_dev->stats.rx_bytes += skb->len;
        memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
        netif_rx(skb);
        return;

dropped:
        net_dev->stats.rx_dropped++;
        goto free_skb;
error:
        net_dev->stats.rx_errors++;
free_skb:
        dev_kfree_skb(skb);
}

/*
 * Assign a vcc to a dev
 * Note: we do not have explicit unassign, but look at _push()
 */
static int br2684_regvcc(struct atm_vcc *atmvcc, void __user * arg)
{
        struct br2684_vcc *brvcc;
        struct br2684_dev *brdev;
        struct net_device *net_dev;
        struct atm_backend_br2684 be;
        int err;

        if (copy_from_user(&be, arg, sizeof be))
                return -EFAULT;
        brvcc = kzalloc(sizeof(struct br2684_vcc), GFP_KERNEL);
        if (!brvcc)
                return -ENOMEM;
        /*
         * Allow two packets in the ATM queue. One actually being sent, and one
         * for the ATM 'TX done' handler to send. It shouldn't take long to get
         * the next one from the netdev queue, when we need it. More than that
         * would be bufferbloat.
         */
        atomic_set(&brvcc->qspace, 2);
        write_lock_irq(&devs_lock);
        net_dev = br2684_find_dev(&be.ifspec);
        if (net_dev == NULL) {
                pr_err("tried to attach to non-existent device\n");
                err = -ENXIO;
                goto error;
        }
        brdev = BRPRIV(net_dev);
        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;
        }
        pr_debug("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(net_dev->dev_addr, esi, net_dev->addr_len);
                else
                        net_dev->dev_addr[2] = 1;
        }
        list_add(&brvcc->brvccs, &brdev->brvccs);
        write_unlock_irq(&devs_lock);
        brvcc->device = net_dev;
        brvcc->atmvcc = atmvcc;
        atmvcc->user_back = brvcc;
        brvcc->encaps = (enum br2684_encaps)be.encaps;
        brvcc->old_push = atmvcc->push;
        brvcc->old_pop = atmvcc->pop;
        brvcc->old_release_cb = atmvcc->release_cb;
        brvcc->old_owner = atmvcc->owner;
        barrier();
        atmvcc->push = br2684_push;
        atmvcc->pop = br2684_pop;
        atmvcc->release_cb = br2684_release_cb;
        atmvcc->owner = THIS_MODULE;

        /* initialize netdev carrier state */
        if (atmvcc->dev->signal == ATM_PHY_SIG_LOST)
                netif_carrier_off(net_dev);
        else
                netif_carrier_on(net_dev);

        __module_get(THIS_MODULE);

        /* re-process everything received between connection setup and
           backend setup */
        vcc_process_recv_queue(atmvcc);
        return 0;

error:
        write_unlock_irq(&devs_lock);
        kfree(brvcc);
        return err;
}

static const struct net_device_ops br2684_netdev_ops = {
        .ndo_start_xmit         = br2684_start_xmit,
        .ndo_set_mac_address    = br2684_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};

static const struct net_device_ops br2684_netdev_ops_routed = {
        .ndo_start_xmit         = br2684_start_xmit,
        .ndo_set_mac_address    = br2684_mac_addr,
};

static void br2684_setup(struct net_device *netdev)
{
        struct br2684_dev *brdev = BRPRIV(netdev);

        ether_setup(netdev);
        netdev->hard_header_len += sizeof(llc_oui_pid_pad); /* worst case */
        brdev->net_dev = netdev;

        netdev->netdev_ops = &br2684_netdev_ops;

        INIT_LIST_HEAD(&brdev->brvccs);
}

static void br2684_setup_routed(struct net_device *netdev)
{
        struct br2684_dev *brdev = BRPRIV(netdev);

        brdev->net_dev = netdev;
        netdev->hard_header_len = sizeof(llc_oui_ipv4); /* worst case */
        netdev->netdev_ops = &br2684_netdev_ops_routed;
        netdev->addr_len = 0;
        netdev->mtu = ETH_DATA_LEN;
        netdev->min_mtu = 0;
        netdev->max_mtu = ETH_MAX_MTU;
        netdev->type = ARPHRD_PPP;
        netdev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
        netdev->tx_queue_len = 100;
        INIT_LIST_HEAD(&brdev->brvccs);
}

static int br2684_create(void __user *arg)
{
        int err;
        struct net_device *netdev;
        struct br2684_dev *brdev;
        struct atm_newif_br2684 ni;
        enum br2684_payload payload;

        pr_debug("\n");

        if (copy_from_user(&ni, arg, sizeof ni))
                return -EFAULT;

        if (ni.media & BR2684_FLAG_ROUTED)
                payload = p_routed;
        else
                payload = p_bridged;
        ni.media &= 0xffff;     /* strip flags */

        if (ni.media != BR2684_MEDIA_ETHERNET || ni.mtu != 1500)
                return -EINVAL;

        netdev = alloc_netdev(sizeof(struct br2684_dev),
                              ni.ifname[0] ? ni.ifname : "nas%d",
                              NET_NAME_UNKNOWN,
                              (payload == p_routed) ? br2684_setup_routed : br2684_setup);
        if (!netdev)
                return -ENOMEM;

        brdev = BRPRIV(netdev);

        pr_debug("registered netdev %s\n", netdev->name);
        /* open, stop, do_ioctl ? */
        err = register_netdev(netdev);
        if (err < 0) {
                pr_err("register_netdev failed\n");
                free_netdev(netdev);
                return err;
        }

        write_lock_irq(&devs_lock);

        brdev->payload = payload;

        if (list_empty(&br2684_devs)) {
                /* 1st br2684 device */
                brdev->number = 1;
        } else
                brdev->number = BRPRIV(list_entry_brdev(br2684_devs.prev))->number + 1;

        list_add_tail(&brdev->br2684_devs, &br2684_devs);
        write_unlock_irq(&devs_lock);
        return 0;
}

/*
 * This handles ioctls actually performed on our vcc - we must return
 * -ENOIOCTLCMD for any unrecognized ioctl
 */
static int br2684_ioctl(struct socket *sock, unsigned int cmd,
                        unsigned long arg)
{
        struct atm_vcc *atmvcc = ATM_SD(sock);
        void __user *argp = (void __user *)arg;
        atm_backend_t b;

        int err;
        switch (cmd) {
        case ATM_SETBACKEND:
        case ATM_NEWBACKENDIF:
                err = get_user(b, (atm_backend_t __user *) argp);
                if (err)
                        return -EFAULT;
                if (b != ATM_BACKEND_BR2684)
                        return -ENOIOCTLCMD;
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                if (cmd == ATM_SETBACKEND) {
                        if (sock->state != SS_CONNECTED)
                                return -EINVAL;
                        return br2684_regvcc(atmvcc, argp);
                } else {
                        return br2684_create(argp);
                }
#ifdef CONFIG_ATM_BR2684_IPFILTER
        case BR2684_SETFILT:
                if (atmvcc->push != br2684_push)
                        return -ENOIOCTLCMD;
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                err = br2684_setfilt(atmvcc, argp);

                return err;
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        }
        return -ENOIOCTLCMD;
}

static struct atm_ioctl br2684_ioctl_ops = {
        .owner = THIS_MODULE,
        .ioctl = br2684_ioctl,
};

#ifdef CONFIG_PROC_FS
static void *br2684_seq_start(struct seq_file *seq, loff_t * pos)
        __acquires(devs_lock)
{
        read_lock(&devs_lock);
        return seq_list_start(&br2684_devs, *pos);
}

static void *br2684_seq_next(struct seq_file *seq, void *v, loff_t * pos)
{
        return seq_list_next(v, &br2684_devs, pos);
}

static void br2684_seq_stop(struct seq_file *seq, void *v)
        __releases(devs_lock)
{
        read_unlock(&devs_lock);
}

static int br2684_seq_show(struct seq_file *seq, void *v)
{
        const struct br2684_dev *brdev = list_entry(v, struct br2684_dev,
                                                    br2684_devs);
        const struct net_device *net_dev = brdev->net_dev;
        const struct br2684_vcc *brvcc;

        seq_printf(seq, "dev %.16s: num=%d, mac=%pM (%s)\n",
                   net_dev->name,
                   brdev->number,
                   net_dev->dev_addr,
                   brdev->mac_was_set ? "set" : "auto");

        list_for_each_entry(brvcc, &brdev->brvccs, brvccs) {
                seq_printf(seq, "  vcc %d.%d.%d: encaps=%s payload=%s"
                           ", failed copies %u/%u"
                           "\n", brvcc->atmvcc->dev->number,
                           brvcc->atmvcc->vpi, brvcc->atmvcc->vci,
                           (brvcc->encaps == e_llc) ? "LLC" : "VC",
                           (brdev->payload == p_bridged) ? "bridged" : "routed",
                           brvcc->copies_failed, brvcc->copies_needed);
#ifdef CONFIG_ATM_BR2684_IPFILTER
                if (brvcc->filter.netmask != 0)
                        seq_printf(seq, "    filter=%pI4/%pI4\n",
                                   &brvcc->filter.prefix,
                                   &brvcc->filter.netmask);
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        }
        return 0;
}

static const struct seq_operations br2684_seq_ops = {
        .start = br2684_seq_start,
        .next = br2684_seq_next,
        .stop = br2684_seq_stop,
        .show = br2684_seq_show,
};

extern struct proc_dir_entry *atm_proc_root;    /* from proc.c */
#endif /* CONFIG_PROC_FS */

static int __init br2684_init(void)
{
#ifdef CONFIG_PROC_FS
        struct proc_dir_entry *p;
        p = proc_create_seq("br2684", 0, atm_proc_root, &br2684_seq_ops);
        if (p == NULL)
                return -ENOMEM;
#endif
        register_atm_ioctl(&br2684_ioctl_ops);
        register_atmdevice_notifier(&atm_dev_notifier);
        return 0;
}

static void __exit br2684_exit(void)
{
        struct net_device *net_dev;
        struct br2684_dev *brdev;
        struct br2684_vcc *brvcc;
        deregister_atm_ioctl(&br2684_ioctl_ops);

#ifdef CONFIG_PROC_FS
        remove_proc_entry("br2684", atm_proc_root);
#endif


        unregister_atmdevice_notifier(&atm_dev_notifier);

        while (!list_empty(&br2684_devs)) {
                net_dev = list_entry_brdev(br2684_devs.next);
                brdev = BRPRIV(net_dev);
                while (!list_empty(&brdev->brvccs)) {
                        brvcc = list_entry_brvcc(brdev->brvccs.next);
                        br2684_close_vcc(brvcc);
                }

                list_del(&brdev->br2684_devs);
                unregister_netdev(net_dev);
                free_netdev(net_dev);
        }
}

module_init(br2684_init);
module_exit(br2684_exit);

MODULE_AUTHOR("Marcell GAL");
MODULE_DESCRIPTION("RFC2684 bridged protocols over ATM/AAL5");
MODULE_LICENSE("GPL");