[mirror_ubuntu-bionic-kernel.git] / net / netfilter / nfnetlink_queue.c

/*
 * This is a module which is used for queueing packets and communicating with
 * userspace via nfetlink.
 *
 * (C) 2005 by Harald Welte <laforge@netfilter.org>
 *
 * Based on the old ipv4-only ip_queue.c:
 * (C) 2000-2002 James Morris <jmorris@intercode.com.au>
 * (C) 2003-2005 Netfilter Core Team <coreteam@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/proc_fs.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <linux/list.h>
#include <net/sock.h>

#include <asm/atomic.h>

#ifdef CONFIG_BRIDGE_NETFILTER
#include "../bridge/br_private.h"
#endif

#define NFQNL_QMAX_DEFAULT 1024

#if 0
#define QDEBUG(x, args ...)     printk(KERN_DEBUG "%s(%d):%s(): " x,       \
                                        __FILE__, __LINE__, __FUNCTION__,  \
                                        ## args)
#else
#define QDEBUG(x, ...)
#endif

struct nfqnl_queue_entry {
        struct list_head list;
        struct nf_info *info;
        struct sk_buff *skb;
        unsigned int id;
};

struct nfqnl_instance {
        struct hlist_node hlist;                /* global list of queues */
        atomic_t use;

        int peer_pid;
        unsigned int queue_maxlen;
        unsigned int copy_range;
        unsigned int queue_total;
        unsigned int queue_dropped;
        unsigned int queue_user_dropped;

        atomic_t id_sequence;                   /* 'sequence' of pkt ids */

        u_int16_t queue_num;                    /* number of this queue */
        u_int8_t copy_mode;

        spinlock_t lock;

        struct list_head queue_list;            /* packets in queue */
};

typedef int (*nfqnl_cmpfn)(struct nfqnl_queue_entry *, unsigned long);

static DEFINE_RWLOCK(instances_lock);

#define INSTANCE_BUCKETS        16
static struct hlist_head instance_table[INSTANCE_BUCKETS];

static inline u_int8_t instance_hashfn(u_int16_t queue_num)
{
        return ((queue_num >> 8) | queue_num) % INSTANCE_BUCKETS;
}

static struct nfqnl_instance *
__instance_lookup(u_int16_t queue_num)
{
        struct hlist_head *head;
        struct hlist_node *pos;
        struct nfqnl_instance *inst;

        head = &instance_table[instance_hashfn(queue_num)];
        hlist_for_each_entry(inst, pos, head, hlist) {
                if (inst->queue_num == queue_num)
                        return inst;
        }
        return NULL;
}

static struct nfqnl_instance *
instance_lookup_get(u_int16_t queue_num)
{
        struct nfqnl_instance *inst;

        read_lock_bh(&instances_lock);
        inst = __instance_lookup(queue_num);
        if (inst)
                atomic_inc(&inst->use);
        read_unlock_bh(&instances_lock);

        return inst;
}

static void
instance_put(struct nfqnl_instance *inst)
{
        if (inst && atomic_dec_and_test(&inst->use)) {
                QDEBUG("kfree(inst=%p)\n", inst);
                kfree(inst);
        }
}

static struct nfqnl_instance *
instance_create(u_int16_t queue_num, int pid)
{
        struct nfqnl_instance *inst;

        QDEBUG("entering for queue_num=%u, pid=%d\n", queue_num, pid);

        write_lock_bh(&instances_lock); 
        if (__instance_lookup(queue_num)) {
                inst = NULL;
                QDEBUG("aborting, instance already exists\n");
                goto out_unlock;
        }

        inst = kzalloc(sizeof(*inst), GFP_ATOMIC);
        if (!inst)
                goto out_unlock;

        inst->queue_num = queue_num;
        inst->peer_pid = pid;
        inst->queue_maxlen = NFQNL_QMAX_DEFAULT;
        inst->copy_range = 0xfffff;
        inst->copy_mode = NFQNL_COPY_NONE;
        atomic_set(&inst->id_sequence, 0);
        /* needs to be two, since we _put() after creation */
        atomic_set(&inst->use, 2);
        spin_lock_init(&inst->lock);
        INIT_LIST_HEAD(&inst->queue_list);

        if (!try_module_get(THIS_MODULE))
                goto out_free;

        hlist_add_head(&inst->hlist, 
                       &instance_table[instance_hashfn(queue_num)]);

        write_unlock_bh(&instances_lock);

        QDEBUG("successfully created new instance\n");

        return inst;

out_free:
        kfree(inst);
out_unlock:
        write_unlock_bh(&instances_lock);
        return NULL;
}

static void nfqnl_flush(struct nfqnl_instance *queue, int verdict);

static void
_instance_destroy2(struct nfqnl_instance *inst, int lock)
{
        /* first pull it out of the global list */
        if (lock)
                write_lock_bh(&instances_lock);

        QDEBUG("removing instance %p (queuenum=%u) from hash\n",
                inst, inst->queue_num);
        hlist_del(&inst->hlist);

        if (lock)
                write_unlock_bh(&instances_lock);

        /* then flush all pending skbs from the queue */
        nfqnl_flush(inst, NF_DROP);

        /* and finally put the refcount */
        instance_put(inst);

        module_put(THIS_MODULE);
}

static inline void
__instance_destroy(struct nfqnl_instance *inst)
{
        _instance_destroy2(inst, 0);
}

static inline void
instance_destroy(struct nfqnl_instance *inst)
{
        _instance_destroy2(inst, 1);
}



static void
issue_verdict(struct nfqnl_queue_entry *entry, int verdict)
{
        QDEBUG("entering for entry %p, verdict %u\n", entry, verdict);

        /* TCP input path (and probably other bits) assume to be called
         * from softirq context, not from syscall, like issue_verdict is
         * called.  TCP input path deadlocks with locks taken from timer
         * softirq, e.g.  We therefore emulate this by local_bh_disable() */

        local_bh_disable();
        nf_reinject(entry->skb, entry->info, verdict);
        local_bh_enable();

        kfree(entry);
}

static inline void
__enqueue_entry(struct nfqnl_instance *queue,
                      struct nfqnl_queue_entry *entry)
{
       list_add(&entry->list, &queue->queue_list);
       queue->queue_total++;
}

/*
 * Find and return a queued entry matched by cmpfn, or return the last
 * entry if cmpfn is NULL.
 */
static inline struct nfqnl_queue_entry *
__find_entry(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, 
                   unsigned long data)
{
        struct list_head *p;

        list_for_each_prev(p, &queue->queue_list) {
                struct nfqnl_queue_entry *entry = (struct nfqnl_queue_entry *)p;
                
                if (!cmpfn || cmpfn(entry, data))
                        return entry;
        }
        return NULL;
}

static inline void
__dequeue_entry(struct nfqnl_instance *q, struct nfqnl_queue_entry *entry)
{
        list_del(&entry->list);
        q->queue_total--;
}

static inline struct nfqnl_queue_entry *
__find_dequeue_entry(struct nfqnl_instance *queue,
                     nfqnl_cmpfn cmpfn, unsigned long data)
{
        struct nfqnl_queue_entry *entry;

        entry = __find_entry(queue, cmpfn, data);
        if (entry == NULL)
                return NULL;

        __dequeue_entry(queue, entry);
        return entry;
}


static inline void
__nfqnl_flush(struct nfqnl_instance *queue, int verdict)
{
        struct nfqnl_queue_entry *entry;
        
        while ((entry = __find_dequeue_entry(queue, NULL, 0)))
                issue_verdict(entry, verdict);
}

static inline int
__nfqnl_set_mode(struct nfqnl_instance *queue,
                 unsigned char mode, unsigned int range)
{
        int status = 0;
        
        switch (mode) {
        case NFQNL_COPY_NONE:
        case NFQNL_COPY_META:
                queue->copy_mode = mode;
                queue->copy_range = 0;
                break;
                
        case NFQNL_COPY_PACKET:
                queue->copy_mode = mode;
                /* we're using struct nfattr which has 16bit nfa_len */
                if (range > 0xffff)
                        queue->copy_range = 0xffff;
                else
                        queue->copy_range = range;
                break;
                
        default:
                status = -EINVAL;

        }
        return status;
}

static struct nfqnl_queue_entry *
find_dequeue_entry(struct nfqnl_instance *queue,
                         nfqnl_cmpfn cmpfn, unsigned long data)
{
        struct nfqnl_queue_entry *entry;
        
        spin_lock_bh(&queue->lock);
        entry = __find_dequeue_entry(queue, cmpfn, data);
        spin_unlock_bh(&queue->lock);

        return entry;
}

static void
nfqnl_flush(struct nfqnl_instance *queue, int verdict)
{
        spin_lock_bh(&queue->lock);
        __nfqnl_flush(queue, verdict);
        spin_unlock_bh(&queue->lock);
}

static struct sk_buff *
nfqnl_build_packet_message(struct nfqnl_instance *queue,
                           struct nfqnl_queue_entry *entry, int *errp)
{
        unsigned char *old_tail;
        size_t size;
        size_t data_len = 0;
        struct sk_buff *skb;
        struct nfqnl_msg_packet_hdr pmsg;
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfmsg;
        struct nf_info *entinf = entry->info;
        struct sk_buff *entskb = entry->skb;
        struct net_device *indev;
        struct net_device *outdev;
        unsigned int tmp_uint;

        QDEBUG("entered\n");

        /* all macros expand to constant values at compile time */
        size =    NLMSG_SPACE(sizeof(struct nfgenmsg)) +
                + NFA_SPACE(sizeof(struct nfqnl_msg_packet_hdr))
                + NFA_SPACE(sizeof(u_int32_t))  /* ifindex */
                + NFA_SPACE(sizeof(u_int32_t))  /* ifindex */
#ifdef CONFIG_BRIDGE_NETFILTER
                + NFA_SPACE(sizeof(u_int32_t))  /* ifindex */
                + NFA_SPACE(sizeof(u_int32_t))  /* ifindex */
#endif
                + NFA_SPACE(sizeof(u_int32_t))  /* mark */
                + NFA_SPACE(sizeof(struct nfqnl_msg_packet_hw))
                + NFA_SPACE(sizeof(struct nfqnl_msg_packet_timestamp));

        outdev = entinf->outdev;

        spin_lock_bh(&queue->lock);
        
        switch (queue->copy_mode) {
        case NFQNL_COPY_META:
        case NFQNL_COPY_NONE:
                data_len = 0;
                break;
        
        case NFQNL_COPY_PACKET:
                if (entskb->ip_summed == CHECKSUM_HW &&
                    (*errp = skb_checksum_help(entskb,
                                               outdev == NULL))) {
                        spin_unlock_bh(&queue->lock);
                        return NULL;
                }
                if (queue->copy_range == 0 
                    || queue->copy_range > entskb->len)
                        data_len = entskb->len;
                else
                        data_len = queue->copy_range;
                
                size += NFA_SPACE(data_len);
                break;
        
        default:
                *errp = -EINVAL;
                spin_unlock_bh(&queue->lock);
                return NULL;
        }

        spin_unlock_bh(&queue->lock);

        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb)
                goto nlmsg_failure;
                
        old_tail= skb->tail;
        nlh = NLMSG_PUT(skb, 0, 0, 
                        NFNL_SUBSYS_QUEUE << 8 | NFQNL_MSG_PACKET,
                        sizeof(struct nfgenmsg));
        nfmsg = NLMSG_DATA(nlh);
        nfmsg->nfgen_family = entinf->pf;
        nfmsg->version = NFNETLINK_V0;
        nfmsg->res_id = htons(queue->queue_num);

        pmsg.packet_id          = htonl(entry->id);
        pmsg.hw_protocol        = htons(entskb->protocol);
        pmsg.hook               = entinf->hook;

        NFA_PUT(skb, NFQA_PACKET_HDR, sizeof(pmsg), &pmsg);

        indev = entinf->indev;
        if (indev) {
                tmp_uint = htonl(indev->ifindex);
#ifndef CONFIG_BRIDGE_NETFILTER
                NFA_PUT(skb, NFQA_IFINDEX_INDEV, sizeof(tmp_uint), &tmp_uint);
#else
                if (entinf->pf == PF_BRIDGE) {
                        /* Case 1: indev is physical input device, we need to
                         * look for bridge group (when called from 
                         * netfilter_bridge) */
                        NFA_PUT(skb, NFQA_IFINDEX_PHYSINDEV, sizeof(tmp_uint), 
                                &tmp_uint);
                        /* this is the bridge group "brX" */
                        tmp_uint = htonl(indev->br_port->br->dev->ifindex);
                        NFA_PUT(skb, NFQA_IFINDEX_INDEV, sizeof(tmp_uint),
                                &tmp_uint);
                } else {
                        /* Case 2: indev is bridge group, we need to look for
                         * physical device (when called from ipv4) */
                        NFA_PUT(skb, NFQA_IFINDEX_INDEV, sizeof(tmp_uint),
                                &tmp_uint);
                        if (entskb->nf_bridge
                            && entskb->nf_bridge->physindev) {
                                tmp_uint = htonl(entskb->nf_bridge->physindev->ifindex);
                                NFA_PUT(skb, NFQA_IFINDEX_PHYSINDEV,
                                        sizeof(tmp_uint), &tmp_uint);
                        }
                }
#endif
        }

        if (outdev) {
                tmp_uint = htonl(outdev->ifindex);
#ifndef CONFIG_BRIDGE_NETFILTER
                NFA_PUT(skb, NFQA_IFINDEX_OUTDEV, sizeof(tmp_uint), &tmp_uint);
#else
                if (entinf->pf == PF_BRIDGE) {
                        /* Case 1: outdev is physical output device, we need to
                         * look for bridge group (when called from 
                         * netfilter_bridge) */
                        NFA_PUT(skb, NFQA_IFINDEX_PHYSOUTDEV, sizeof(tmp_uint),
                                &tmp_uint);
                        /* this is the bridge group "brX" */
                        tmp_uint = htonl(outdev->br_port->br->dev->ifindex);
                        NFA_PUT(skb, NFQA_IFINDEX_OUTDEV, sizeof(tmp_uint),
                                &tmp_uint);
                } else {
                        /* Case 2: outdev is bridge group, we need to look for
                         * physical output device (when called from ipv4) */
                        NFA_PUT(skb, NFQA_IFINDEX_OUTDEV, sizeof(tmp_uint),
                                &tmp_uint);
                        if (entskb->nf_bridge
                            && entskb->nf_bridge->physoutdev) {
                                tmp_uint = htonl(entskb->nf_bridge->physoutdev->ifindex);
                                NFA_PUT(skb, NFQA_IFINDEX_PHYSOUTDEV,
                                        sizeof(tmp_uint), &tmp_uint);
                        }
                }
#endif
        }

        if (entskb->nfmark) {
                tmp_uint = htonl(entskb->nfmark);
                NFA_PUT(skb, NFQA_MARK, sizeof(u_int32_t), &tmp_uint);
        }

        if (indev && entskb->dev
            && entskb->dev->hard_header_parse) {
                struct nfqnl_msg_packet_hw phw;

                phw.hw_addrlen =
                        entskb->dev->hard_header_parse(entskb,
                                                           phw.hw_addr);
                phw.hw_addrlen = htons(phw.hw_addrlen);
                NFA_PUT(skb, NFQA_HWADDR, sizeof(phw), &phw);
        }

        if (entskb->tstamp.off_sec) {
                struct nfqnl_msg_packet_timestamp ts;

                ts.sec = cpu_to_be64(entskb->tstamp.off_sec);
                ts.usec = cpu_to_be64(entskb->tstamp.off_usec);

                NFA_PUT(skb, NFQA_TIMESTAMP, sizeof(ts), &ts);
        }

        if (data_len) {
                struct nfattr *nfa;
                int size = NFA_LENGTH(data_len);

                if (skb_tailroom(skb) < (int)NFA_SPACE(data_len)) {
                        printk(KERN_WARNING "nf_queue: no tailroom!\n");
                        goto nlmsg_failure;
                }

                nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
                nfa->nfa_type = NFQA_PAYLOAD;
                nfa->nfa_len = size;

                if (skb_copy_bits(entskb, 0, NFA_DATA(nfa), data_len))
                        BUG();
        }
                
        nlh->nlmsg_len = skb->tail - old_tail;
        return skb;

nlmsg_failure:
nfattr_failure:
        if (skb)
                kfree_skb(skb);
        *errp = -EINVAL;
        if (net_ratelimit())
                printk(KERN_ERR "nf_queue: error creating packet message\n");
        return NULL;
}

static int
nfqnl_enqueue_packet(struct sk_buff *skb, struct nf_info *info, 
                     unsigned int queuenum, void *data)
{
        int status = -EINVAL;
        struct sk_buff *nskb;
        struct nfqnl_instance *queue;
        struct nfqnl_queue_entry *entry;

        QDEBUG("entered\n");

        queue = instance_lookup_get(queuenum);
        if (!queue) {
                QDEBUG("no queue instance matching\n");
                return -EINVAL;
        }

        if (queue->copy_mode == NFQNL_COPY_NONE) {
                QDEBUG("mode COPY_NONE, aborting\n");
                status = -EAGAIN;
                goto err_out_put;
        }

        entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
        if (entry == NULL) {
                if (net_ratelimit())
                        printk(KERN_ERR 
                                "nf_queue: OOM in nfqnl_enqueue_packet()\n");
                status = -ENOMEM;
                goto err_out_put;
        }

        entry->info = info;
        entry->skb = skb;
        entry->id = atomic_inc_return(&queue->id_sequence);

        nskb = nfqnl_build_packet_message(queue, entry, &status);
        if (nskb == NULL)
                goto err_out_free;
                
        spin_lock_bh(&queue->lock);
        
        if (!queue->peer_pid)
                goto err_out_free_nskb; 

        if (queue->queue_total >= queue->queue_maxlen) {
                queue->queue_dropped++;
                status = -ENOSPC;
                if (net_ratelimit())
                          printk(KERN_WARNING "ip_queue: full at %d entries, "
                                 "dropping packets(s). Dropped: %d\n", 
                                 queue->queue_total, queue->queue_dropped);
                goto err_out_free_nskb;
        }

        /* nfnetlink_unicast will either free the nskb or add it to a socket */
        status = nfnetlink_unicast(nskb, queue->peer_pid, MSG_DONTWAIT);
        if (status < 0) {
                queue->queue_user_dropped++;
                goto err_out_unlock;
        }

        __enqueue_entry(queue, entry);

        spin_unlock_bh(&queue->lock);
        instance_put(queue);
        return status;

err_out_free_nskb:
        kfree_skb(nskb); 
        
err_out_unlock:
        spin_unlock_bh(&queue->lock);

err_out_free:
        kfree(entry);
err_out_put:
        instance_put(queue);
        return status;
}

static int
nfqnl_mangle(void *data, int data_len, struct nfqnl_queue_entry *e)
{
        int diff;

        diff = data_len - e->skb->len;
        if (diff < 0)
                skb_trim(e->skb, data_len);
        else if (diff > 0) {
                if (data_len > 0xFFFF)
                        return -EINVAL;
                if (diff > skb_tailroom(e->skb)) {
                        struct sk_buff *newskb;
                        
                        newskb = skb_copy_expand(e->skb,
                                                 skb_headroom(e->skb),
                                                 diff,
                                                 GFP_ATOMIC);
                        if (newskb == NULL) {
                                printk(KERN_WARNING "ip_queue: OOM "
                                      "in mangle, dropping packet\n");
                                return -ENOMEM;
                        }
                        if (e->skb->sk)
                                skb_set_owner_w(newskb, e->skb->sk);
                        kfree_skb(e->skb);
                        e->skb = newskb;
                }
                skb_put(e->skb, diff);
        }
        if (!skb_make_writable(&e->skb, data_len))
                return -ENOMEM;
        memcpy(e->skb->data, data, data_len);
        e->skb->ip_summed = CHECKSUM_NONE;
        return 0;
}

static inline int
id_cmp(struct nfqnl_queue_entry *e, unsigned long id)
{
        return (id == e->id);
}

static int
nfqnl_set_mode(struct nfqnl_instance *queue,
               unsigned char mode, unsigned int range)
{
        int status;

        spin_lock_bh(&queue->lock);
        status = __nfqnl_set_mode(queue, mode, range);
        spin_unlock_bh(&queue->lock);

        return status;
}

static int
dev_cmp(struct nfqnl_queue_entry *entry, unsigned long ifindex)
{
        struct nf_info *entinf = entry->info;
        
        if (entinf->indev)
                if (entinf->indev->ifindex == ifindex)
                        return 1;
                        
        if (entinf->outdev)
                if (entinf->outdev->ifindex == ifindex)
                        return 1;

        return 0;
}

/* drop all packets with either indev or outdev == ifindex from all queue
 * instances */
static void
nfqnl_dev_drop(int ifindex)
{
        int i;
        
        QDEBUG("entering for ifindex %u\n", ifindex);

        /* this only looks like we have to hold the readlock for a way too long
         * time, issue_verdict(),  nf_reinject(), ... - but we always only
         * issue NF_DROP, which is processed directly in nf_reinject() */
        read_lock_bh(&instances_lock);

        for  (i = 0; i < INSTANCE_BUCKETS; i++) {
                struct hlist_node *tmp;
                struct nfqnl_instance *inst;
                struct hlist_head *head = &instance_table[i];

                hlist_for_each_entry(inst, tmp, head, hlist) {
                        struct nfqnl_queue_entry *entry;
                        while ((entry = find_dequeue_entry(inst, dev_cmp, 
                                                           ifindex)) != NULL)
                                issue_verdict(entry, NF_DROP);
                }
        }

        read_unlock_bh(&instances_lock);
}

#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)

static int
nfqnl_rcv_dev_event(struct notifier_block *this,
                    unsigned long event, void *ptr)
{
        struct net_device *dev = ptr;

        /* Drop any packets associated with the downed device */
        if (event == NETDEV_DOWN)
                nfqnl_dev_drop(dev->ifindex);
        return NOTIFY_DONE;
}

static struct notifier_block nfqnl_dev_notifier = {
        .notifier_call  = nfqnl_rcv_dev_event,
};

static int
nfqnl_rcv_nl_event(struct notifier_block *this,
                   unsigned long event, void *ptr)
{
        struct netlink_notify *n = ptr;

        if (event == NETLINK_URELEASE &&
            n->protocol == NETLINK_NETFILTER && n->pid) {
                int i;

                /* destroy all instances for this pid */
                write_lock_bh(&instances_lock);
                for  (i = 0; i < INSTANCE_BUCKETS; i++) {
                        struct hlist_node *tmp, *t2;
                        struct nfqnl_instance *inst;
                        struct hlist_head *head = &instance_table[i];

                        hlist_for_each_entry_safe(inst, tmp, t2, head, hlist) {
                                if (n->pid == inst->peer_pid)
                                        __instance_destroy(inst);
                        }
                }
                write_unlock_bh(&instances_lock);
        }
        return NOTIFY_DONE;
}

static struct notifier_block nfqnl_rtnl_notifier = {
        .notifier_call  = nfqnl_rcv_nl_event,
};

static const int nfqa_verdict_min[NFQA_MAX] = {
        [NFQA_VERDICT_HDR-1]    = sizeof(struct nfqnl_msg_verdict_hdr),
        [NFQA_MARK-1]           = sizeof(u_int32_t),
        [NFQA_PAYLOAD-1]        = 0,
};

static int
nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb,
                   struct nlmsghdr *nlh, struct nfattr *nfqa[], int *errp)
{
        struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
        u_int16_t queue_num = ntohs(nfmsg->res_id);

        struct nfqnl_msg_verdict_hdr *vhdr;
        struct nfqnl_instance *queue;
        unsigned int verdict;
        struct nfqnl_queue_entry *entry;
        int err;

        if (nfattr_bad_size(nfqa, NFQA_MAX, nfqa_verdict_min)) {
                QDEBUG("bad attribute size\n");
                return -EINVAL;
        }

        queue = instance_lookup_get(queue_num);
        if (!queue)
                return -ENODEV;

        if (queue->peer_pid != NETLINK_CB(skb).pid) {
                err = -EPERM;
                goto err_out_put;
        }

        if (!nfqa[NFQA_VERDICT_HDR-1]) {
                err = -EINVAL;
                goto err_out_put;
        }

        vhdr = NFA_DATA(nfqa[NFQA_VERDICT_HDR-1]);
        verdict = ntohl(vhdr->verdict);

        if ((verdict & NF_VERDICT_MASK) > NF_MAX_VERDICT) {
                err = -EINVAL;
                goto err_out_put;
        }

        entry = find_dequeue_entry(queue, id_cmp, ntohl(vhdr->id));
        if (entry == NULL) {
                err = -ENOENT;
                goto err_out_put;
        }

        if (nfqa[NFQA_PAYLOAD-1]) {
                if (nfqnl_mangle(NFA_DATA(nfqa[NFQA_PAYLOAD-1]),
                                 NFA_PAYLOAD(nfqa[NFQA_PAYLOAD-1]), entry) < 0)
                        verdict = NF_DROP;
        }

        if (nfqa[NFQA_MARK-1])
                entry->skb->nfmark = ntohl(*(u_int32_t *)
                                           NFA_DATA(nfqa[NFQA_MARK-1]));
                
        issue_verdict(entry, verdict);
        instance_put(queue);
        return 0;

err_out_put:
        instance_put(queue);
        return err;
}

static int
nfqnl_recv_unsupp(struct sock *ctnl, struct sk_buff *skb,
                  struct nlmsghdr *nlh, struct nfattr *nfqa[], int *errp)
{
        return -ENOTSUPP;
}

static const int nfqa_cfg_min[NFQA_CFG_MAX] = {
        [NFQA_CFG_CMD-1]        = sizeof(struct nfqnl_msg_config_cmd),
        [NFQA_CFG_PARAMS-1]     = sizeof(struct nfqnl_msg_config_params),
};

static struct nf_queue_handler nfqh = {
        .name   = "nf_queue",
        .outfn  = &nfqnl_enqueue_packet,
};

static int
nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
                  struct nlmsghdr *nlh, struct nfattr *nfqa[], int *errp)
{
        struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
        u_int16_t queue_num = ntohs(nfmsg->res_id);
        struct nfqnl_instance *queue;
        int ret = 0;

        QDEBUG("entering for msg %u\n", NFNL_MSG_TYPE(nlh->nlmsg_type));

        if (nfattr_bad_size(nfqa, NFQA_CFG_MAX, nfqa_cfg_min)) {
                QDEBUG("bad attribute size\n");
                return -EINVAL;
        }

        queue = instance_lookup_get(queue_num);
        if (nfqa[NFQA_CFG_CMD-1]) {
                struct nfqnl_msg_config_cmd *cmd;
                cmd = NFA_DATA(nfqa[NFQA_CFG_CMD-1]);
                QDEBUG("found CFG_CMD\n");

                switch (cmd->command) {
                case NFQNL_CFG_CMD_BIND:
                        if (queue)
                                return -EBUSY;

                        queue = instance_create(queue_num, NETLINK_CB(skb).pid);
                        if (!queue)
                                return -EINVAL;
                        break;
                case NFQNL_CFG_CMD_UNBIND:
                        if (!queue)
                                return -ENODEV;

                        if (queue->peer_pid != NETLINK_CB(skb).pid) {
                                ret = -EPERM;
                                goto out_put;
                        }

                        instance_destroy(queue);
                        break;
                case NFQNL_CFG_CMD_PF_BIND:
                        QDEBUG("registering queue handler for pf=%u\n",
                                ntohs(cmd->pf));
                        ret = nf_register_queue_handler(ntohs(cmd->pf), &nfqh);
                        break;
                case NFQNL_CFG_CMD_PF_UNBIND:
                        QDEBUG("unregistering queue handler for pf=%u\n",
                                ntohs(cmd->pf));
                        /* This is a bug and a feature.  We can unregister
                         * other handlers(!) */
                        ret = nf_unregister_queue_handler(ntohs(cmd->pf));
                        break;
                default:
                        ret = -EINVAL;
                        break;
                }
        } else {
                if (!queue) {
                        QDEBUG("no config command, and no instance ENOENT\n");
                        ret = -ENOENT;
                        goto out_put;
                }

                if (queue->peer_pid != NETLINK_CB(skb).pid) {
                        QDEBUG("no config command, and wrong pid\n");
                        ret = -EPERM;
                        goto out_put;
                }
        }

        if (nfqa[NFQA_CFG_PARAMS-1]) {
                struct nfqnl_msg_config_params *params;

                if (!queue) {
                        ret = -ENOENT;
                        goto out_put;
                }
                params = NFA_DATA(nfqa[NFQA_CFG_PARAMS-1]);
                nfqnl_set_mode(queue, params->copy_mode,
                                ntohl(params->copy_range));
        }

out_put:
        instance_put(queue);
        return ret;
}

static struct nfnl_callback nfqnl_cb[NFQNL_MSG_MAX] = {
        [NFQNL_MSG_PACKET]      = { .call = nfqnl_recv_unsupp,
                                    .attr_count = NFQA_MAX, },
        [NFQNL_MSG_VERDICT]     = { .call = nfqnl_recv_verdict,
                                    .attr_count = NFQA_MAX, },
        [NFQNL_MSG_CONFIG]      = { .call = nfqnl_recv_config,
                                    .attr_count = NFQA_CFG_MAX, },
};

static struct nfnetlink_subsystem nfqnl_subsys = {
        .name           = "nf_queue",
        .subsys_id      = NFNL_SUBSYS_QUEUE,
        .cb_count       = NFQNL_MSG_MAX,
        .cb             = nfqnl_cb,
};

#ifdef CONFIG_PROC_FS
struct iter_state {
        unsigned int bucket;
};

static struct hlist_node *get_first(struct seq_file *seq)
{
        struct iter_state *st = seq->private;

        if (!st)
                return NULL;

        for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {
                if (!hlist_empty(&instance_table[st->bucket]))
                        return instance_table[st->bucket].first;
        }
        return NULL;
}

static struct hlist_node *get_next(struct seq_file *seq, struct hlist_node *h)
{
        struct iter_state *st = seq->private;

        h = h->next;
        while (!h) {
                if (++st->bucket >= INSTANCE_BUCKETS)
                        return NULL;

                h = instance_table[st->bucket].first;
        }
        return h;
}

static struct hlist_node *get_idx(struct seq_file *seq, loff_t pos)
{
        struct hlist_node *head;
        head = get_first(seq);

        if (head)
                while (pos && (head = get_next(seq, head)))
                        pos--;
        return pos ? NULL : head;
}

static void *seq_start(struct seq_file *seq, loff_t *pos)
{
        read_lock_bh(&instances_lock);
        return get_idx(seq, *pos);
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        (*pos)++;
        return get_next(s, v);
}

static void seq_stop(struct seq_file *s, void *v)
{
        read_unlock_bh(&instances_lock);
}

static int seq_show(struct seq_file *s, void *v)
{
        const struct nfqnl_instance *inst = v;

        return seq_printf(s, "%5d %6d %5d %1d %5d %5d %5d %8d %2d\n",
                          inst->queue_num,
                          inst->peer_pid, inst->queue_total,
                          inst->copy_mode, inst->copy_range,
                          inst->queue_dropped, inst->queue_user_dropped,
                          atomic_read(&inst->id_sequence),
                          atomic_read(&inst->use));
}

static struct seq_operations nfqnl_seq_ops = {
        .start  = seq_start,
        .next   = seq_next,
        .stop   = seq_stop,
        .show   = seq_show,
};

static int nfqnl_open(struct inode *inode, struct file *file)
{
        struct seq_file *seq;
        struct iter_state *is;
        int ret;

        is = kzalloc(sizeof(*is), GFP_KERNEL);
        if (!is)
                return -ENOMEM;
        ret = seq_open(file, &nfqnl_seq_ops);
        if (ret < 0)
                goto out_free;
        seq = file->private_data;
        seq->private = is;
        return ret;
out_free:
        kfree(is);
        return ret;
}

static struct file_operations nfqnl_file_ops = {
        .owner   = THIS_MODULE,
        .open    = nfqnl_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release_private,
};

#endif /* PROC_FS */

static int __init nfnetlink_queue_init(void)
{
        int i, status = -ENOMEM;
#ifdef CONFIG_PROC_FS
        struct proc_dir_entry *proc_nfqueue;
#endif
        
        for (i = 0; i < INSTANCE_BUCKETS; i++)
                INIT_HLIST_HEAD(&instance_table[i]);

        netlink_register_notifier(&nfqnl_rtnl_notifier);
        status = nfnetlink_subsys_register(&nfqnl_subsys);
        if (status < 0) {
                printk(KERN_ERR "nf_queue: failed to create netlink socket\n");
                goto cleanup_netlink_notifier;
        }

#ifdef CONFIG_PROC_FS
        proc_nfqueue = create_proc_entry("nfnetlink_queue", 0440,
                                         proc_net_netfilter);
        if (!proc_nfqueue)
                goto cleanup_subsys;
        proc_nfqueue->proc_fops = &nfqnl_file_ops;
#endif

        register_netdevice_notifier(&nfqnl_dev_notifier);
        return status;

#ifdef CONFIG_PROC_FS
cleanup_subsys:
        nfnetlink_subsys_unregister(&nfqnl_subsys);
#endif
cleanup_netlink_notifier:
        netlink_unregister_notifier(&nfqnl_rtnl_notifier);
        return status;
}

static void __exit nfnetlink_queue_fini(void)
{
        nf_unregister_queue_handlers(&nfqh);
        unregister_netdevice_notifier(&nfqnl_dev_notifier);
#ifdef CONFIG_PROC_FS
        remove_proc_entry("nfnetlink_queue", proc_net_netfilter);
#endif
        nfnetlink_subsys_unregister(&nfqnl_subsys);
        netlink_unregister_notifier(&nfqnl_rtnl_notifier);
}

MODULE_DESCRIPTION("netfilter packet queue handler");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_QUEUE);

module_init(nfnetlink_queue_init);
module_exit(nfnetlink_queue_fini);