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nfnetlink_log.c

/*
 * This is a module which is used for logging packets to userspace via
 * nfetlink.
 *
 * (C) 2005 by Harald Welte <laforge@netfilter.org>
 *
 * Based on the old ipv4-only ipt_ULOG.c:
 * (C) 2000-2004 by Harald Welte <laforge@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/ip.h>
#include <linux/ipv6.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/netlink.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_log.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/random.h>
#include <net/sock.h>

#include <asm/atomic.h>

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

#define NFULNL_NLBUFSIZ_DEFAULT     NLMSG_GOODSIZE
#define NFULNL_TIMEOUT_DEFAULT      HZ    /* every second */
#define NFULNL_QTHRESH_DEFAULT      100   /* 100 packets */
#define NFULNL_COPY_RANGE_MAX 0xFFFF      /* max packet size is limited by 16-bit struct nfattr nfa_len field */

#define PRINTR(x, args...)    do { if (net_ratelimit()) \
                             printk(x, ## args); } while (0);

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

struct nfulnl_instance {
      struct hlist_node hlist;      /* global list of instances */
      spinlock_t lock;
      atomic_t use;                 /* use count */

      unsigned int qlen;            /* number of nlmsgs in skb */
      struct sk_buff *skb;          /* pre-allocatd skb */
      struct timer_list timer;
      int peer_pid;                 /* PID of the peer process */

      /* configurable parameters */
      unsigned int flushtimeout;    /* timeout until queue flush */
      unsigned int nlbufsiz;        /* netlink buffer allocation size */
      unsigned int qthreshold;      /* threshold of the queue */
      u_int32_t copy_range;
      u_int32_t seq;                /* instance-local sequential counter */
      u_int16_t group_num;          /* number of this queue */
      u_int16_t flags;
      u_int8_t copy_mode;
};

static DEFINE_RWLOCK(instances_lock);
static atomic_t global_seq;

#define INSTANCE_BUCKETS      16
static struct hlist_head instance_table[INSTANCE_BUCKETS];
static unsigned int hash_init;

static inline u_int8_t instance_hashfn(u_int16_t group_num)
{
      return ((group_num & 0xff) % INSTANCE_BUCKETS);
}

static struct nfulnl_instance *
__instance_lookup(u_int16_t group_num)
{
      struct hlist_head *head;
      struct hlist_node *pos;
      struct nfulnl_instance *inst;

      UDEBUG("entering (group_num=%u)\n", group_num);

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

static inline void
instance_get(struct nfulnl_instance *inst)
{
      atomic_inc(&inst->use);
}

static struct nfulnl_instance *
instance_lookup_get(u_int16_t group_num)
{
      struct nfulnl_instance *inst;

      read_lock_bh(&instances_lock);
      inst = __instance_lookup(group_num);
      if (inst)
            instance_get(inst);
      read_unlock_bh(&instances_lock);

      return inst;
}

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

static void nfulnl_timer(unsigned long data);

static struct nfulnl_instance *
instance_create(u_int16_t group_num, int pid)
{
      struct nfulnl_instance *inst;

      UDEBUG("entering (group_num=%u, pid=%d)\n", group_num,
            pid);

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

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

      if (!try_module_get(THIS_MODULE)) {
            kfree(inst);
            goto out_unlock;
      }

      INIT_HLIST_NODE(&inst->hlist);
      spin_lock_init(&inst->lock);
      /* needs to be two, since we _put() after creation */
      atomic_set(&inst->use, 2);

      setup_timer(&inst->timer, nfulnl_timer, (unsigned long)inst);

      inst->peer_pid = pid;
      inst->group_num = group_num;

      inst->qthreshold  = NFULNL_QTHRESH_DEFAULT;
      inst->flushtimeout      = NFULNL_TIMEOUT_DEFAULT;
      inst->nlbufsiz          = NFULNL_NLBUFSIZ_DEFAULT;
      inst->copy_mode   = NFULNL_COPY_PACKET;
      inst->copy_range  = NFULNL_COPY_RANGE_MAX;

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

      UDEBUG("newly added node: %p, next=%p\n", &inst->hlist,
            inst->hlist.next);

      write_unlock_bh(&instances_lock);

      return inst;

out_unlock:
      write_unlock_bh(&instances_lock);
      return NULL;
}

static void __nfulnl_flush(struct nfulnl_instance *inst);

static void
__instance_destroy(struct nfulnl_instance *inst)
{
      /* first pull it out of the global list */
      UDEBUG("removing instance %p (queuenum=%u) from hash\n",
            inst, inst->group_num);

      hlist_del(&inst->hlist);

      /* then flush all pending packets from skb */

      spin_lock_bh(&inst->lock);
      if (inst->skb)
            __nfulnl_flush(inst);
      spin_unlock_bh(&inst->lock);

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

static inline void
instance_destroy(struct nfulnl_instance *inst)
{
      write_lock_bh(&instances_lock);
      __instance_destroy(inst);
      write_unlock_bh(&instances_lock);
}

static int
nfulnl_set_mode(struct nfulnl_instance *inst, u_int8_t mode,
              unsigned int range)
{
      int status = 0;

      spin_lock_bh(&inst->lock);

      switch (mode) {
      case NFULNL_COPY_NONE:
      case NFULNL_COPY_META:
            inst->copy_mode = mode;
            inst->copy_range = 0;
            break;

      case NFULNL_COPY_PACKET:
            inst->copy_mode = mode;
            inst->copy_range = min_t(unsigned int,
                               range, NFULNL_COPY_RANGE_MAX);
            break;

      default:
            status = -EINVAL;
            break;
      }

      spin_unlock_bh(&inst->lock);

      return status;
}

static int
nfulnl_set_nlbufsiz(struct nfulnl_instance *inst, u_int32_t nlbufsiz)
{
      int status;

      spin_lock_bh(&inst->lock);
      if (nlbufsiz < NFULNL_NLBUFSIZ_DEFAULT)
            status = -ERANGE;
      else if (nlbufsiz > 131072)
            status = -ERANGE;
      else {
            inst->nlbufsiz = nlbufsiz;
            status = 0;
      }
      spin_unlock_bh(&inst->lock);

      return status;
}

static int
nfulnl_set_timeout(struct nfulnl_instance *inst, u_int32_t timeout)
{
      spin_lock_bh(&inst->lock);
      inst->flushtimeout = timeout;
      spin_unlock_bh(&inst->lock);

      return 0;
}

static int
nfulnl_set_qthresh(struct nfulnl_instance *inst, u_int32_t qthresh)
{
      spin_lock_bh(&inst->lock);
      inst->qthreshold = qthresh;
      spin_unlock_bh(&inst->lock);

      return 0;
}

static int
nfulnl_set_flags(struct nfulnl_instance *inst, u_int16_t flags)
{
      spin_lock_bh(&inst->lock);
      inst->flags = flags;
      spin_unlock_bh(&inst->lock);

      return 0;
}

static struct sk_buff *
nfulnl_alloc_skb(unsigned int inst_size, unsigned int pkt_size)
{
      struct sk_buff *skb;
      unsigned int n;

      UDEBUG("entered (%u, %u)\n", inst_size, pkt_size);

      /* alloc skb which should be big enough for a whole multipart
       * message.  WARNING: has to be <= 128k due to slab restrictions */

      n = max(inst_size, pkt_size);
      skb = alloc_skb(n, GFP_ATOMIC);
      if (!skb) {
            PRINTR("nfnetlink_log: can't alloc whole buffer (%u bytes)\n",
                  inst_size);

            if (n > pkt_size) {
                  /* try to allocate only as much as we need for current
                   * packet */

                  skb = alloc_skb(pkt_size, GFP_ATOMIC);
                  if (!skb)
                        PRINTR("nfnetlink_log: can't even alloc %u "
                               "bytes\n", pkt_size);
            }
      }

      return skb;
}

static int
__nfulnl_send(struct nfulnl_instance *inst)
{
      int status = -1;

      if (inst->qlen > 1)
            NLMSG_PUT(inst->skb, 0, 0,
                    NLMSG_DONE,
                    sizeof(struct nfgenmsg));

      status = nfnetlink_unicast(inst->skb, inst->peer_pid, MSG_DONTWAIT);
      if (status < 0) {
            UDEBUG("netlink_unicast() failed\n");
            /* FIXME: statistics */
      }

      inst->qlen = 0;
      inst->skb = NULL;

nlmsg_failure:
      return status;
}

static void
__nfulnl_flush(struct nfulnl_instance *inst)
{
      /* timer holds a reference */
      if (del_timer(&inst->timer))
            instance_put(inst);
      if (inst->skb)
            __nfulnl_send(inst);
}

static void
nfulnl_timer(unsigned long data)
{
      struct nfulnl_instance *inst = (struct nfulnl_instance *)data;

      UDEBUG("timer function called, flushing buffer\n");

      spin_lock_bh(&inst->lock);
      if (inst->skb)
            __nfulnl_send(inst);
      spin_unlock_bh(&inst->lock);
      instance_put(inst);
}

/* This is an inline function, we don't really care about a long
 * list of arguments */
static inline int
__build_packet_message(struct nfulnl_instance *inst,
                  const struct sk_buff *skb,
                  unsigned int data_len,
                  unsigned int pf,
                  unsigned int hooknum,
                  const struct net_device *indev,
                  const struct net_device *outdev,
                  const struct nf_loginfo *li,
                  const char *prefix, unsigned int plen)
{
      struct nfulnl_msg_packet_hdr pmsg;
      struct nlmsghdr *nlh;
      struct nfgenmsg *nfmsg;
      __be32 tmp_uint;
      sk_buff_data_t old_tail = inst->skb->tail;

      UDEBUG("entered\n");

      nlh = NLMSG_PUT(inst->skb, 0, 0,
                  NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET,
                  sizeof(struct nfgenmsg));
      nfmsg = NLMSG_DATA(nlh);
      nfmsg->nfgen_family = pf;
      nfmsg->version = NFNETLINK_V0;
      nfmsg->res_id = htons(inst->group_num);

      pmsg.hw_protocol  = skb->protocol;
      pmsg.hook         = hooknum;

      NLA_PUT(inst->skb, NFULA_PACKET_HDR, sizeof(pmsg), &pmsg);

      if (prefix)
            NLA_PUT(inst->skb, NFULA_PREFIX, plen, prefix);

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

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

      if (skb->mark) {
            tmp_uint = htonl(skb->mark);
            NLA_PUT(inst->skb, NFULA_MARK, sizeof(tmp_uint), &tmp_uint);
      }

      if (indev && skb->dev) {
            struct nfulnl_msg_packet_hw phw;
            int len = dev_parse_header(skb, phw.hw_addr);
            if (len > 0) {
                  phw.hw_addrlen = htons(len);
                  NLA_PUT(inst->skb, NFULA_HWADDR, sizeof(phw), &phw);
            }
      }

      if (skb->tstamp.tv64) {
            struct nfulnl_msg_packet_timestamp ts;
            struct timeval tv = ktime_to_timeval(skb->tstamp);
            ts.sec = cpu_to_be64(tv.tv_sec);
            ts.usec = cpu_to_be64(tv.tv_usec);

            NLA_PUT(inst->skb, NFULA_TIMESTAMP, sizeof(ts), &ts);
      }

      /* UID */
      if (skb->sk) {
            read_lock_bh(&skb->sk->sk_callback_lock);
            if (skb->sk->sk_socket && skb->sk->sk_socket->file) {
                  __be32 uid = htonl(skb->sk->sk_socket->file->f_uid);
                  /* need to unlock here since NLA_PUT may goto */
                  read_unlock_bh(&skb->sk->sk_callback_lock);
                  NLA_PUT(inst->skb, NFULA_UID, sizeof(uid), &uid);
            } else
                  read_unlock_bh(&skb->sk->sk_callback_lock);
      }

      /* local sequence number */
      if (inst->flags & NFULNL_CFG_F_SEQ) {
            tmp_uint = htonl(inst->seq++);
            NLA_PUT(inst->skb, NFULA_SEQ, sizeof(tmp_uint), &tmp_uint);
      }
      /* global sequence number */
      if (inst->flags & NFULNL_CFG_F_SEQ_GLOBAL) {
            tmp_uint = htonl(atomic_inc_return(&global_seq));
            NLA_PUT(inst->skb, NFULA_SEQ_GLOBAL, sizeof(tmp_uint), &tmp_uint);
      }

      if (data_len) {
            struct nlattr *nla;
            int size = nla_attr_size(data_len);

            if (skb_tailroom(inst->skb) < nla_total_size(data_len)) {
                  printk(KERN_WARNING "nfnetlink_log: no tailroom!\n");
                  goto nlmsg_failure;
            }

            nla = (struct nlattr *)skb_put(inst->skb, nla_total_size(data_len));
            nla->nla_type = NFULA_PAYLOAD;
            nla->nla_len = size;

            if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
                  BUG();
      }

      nlh->nlmsg_len = inst->skb->tail - old_tail;
      return 0;

nlmsg_failure:
      UDEBUG("nlmsg_failure\n");
nla_put_failure:
      PRINTR(KERN_ERR "nfnetlink_log: error creating log nlmsg\n");
      return -1;
}

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

static struct nf_loginfo default_loginfo = {
      .type =           NF_LOG_TYPE_ULOG,
      .u = {
            .ulog = {
                  .copy_len   = 0xffff,
                  .group            = 0,
                  .qthreshold = 1,
            },
      },
};

/* log handler for internal netfilter logging api */
static void
nfulnl_log_packet(unsigned int pf,
              unsigned int hooknum,
              const struct sk_buff *skb,
              const struct net_device *in,
              const struct net_device *out,
              const struct nf_loginfo *li_user,
              const char *prefix)
{
      unsigned int size, data_len;
      struct nfulnl_instance *inst;
      const struct nf_loginfo *li;
      unsigned int qthreshold;
      unsigned int plen;

      if (li_user && li_user->type == NF_LOG_TYPE_ULOG)
            li = li_user;
      else
            li = &default_loginfo;

      inst = instance_lookup_get(li->u.ulog.group);
      if (!inst)
            return;

      plen = 0;
      if (prefix)
            plen = strlen(prefix) + 1;

      /* FIXME: do we want to make the size calculation conditional based on
       * what is actually present?  way more branches and checks, but more
       * memory efficient... */
      size =    NLMSG_ALIGN(sizeof(struct nfgenmsg))
            + nla_total_size(sizeof(struct nfulnl_msg_packet_hdr))
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
#ifdef CONFIG_BRIDGE_NETFILTER
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
#endif
            + nla_total_size(sizeof(u_int32_t)) /* mark */
            + nla_total_size(sizeof(u_int32_t)) /* uid */
            + nla_total_size(plen)              /* prefix */
            + nla_total_size(sizeof(struct nfulnl_msg_packet_hw))
            + nla_total_size(sizeof(struct nfulnl_msg_packet_timestamp));

      UDEBUG("initial size=%u\n", size);

      spin_lock_bh(&inst->lock);

      if (inst->flags & NFULNL_CFG_F_SEQ)
            size += nla_total_size(sizeof(u_int32_t));
      if (inst->flags & NFULNL_CFG_F_SEQ_GLOBAL)
            size += nla_total_size(sizeof(u_int32_t));

      qthreshold = inst->qthreshold;
      /* per-rule qthreshold overrides per-instance */
      if (qthreshold > li->u.ulog.qthreshold)
            qthreshold = li->u.ulog.qthreshold;

      switch (inst->copy_mode) {
      case NFULNL_COPY_META:
      case NFULNL_COPY_NONE:
            data_len = 0;
            break;

      case NFULNL_COPY_PACKET:
            if (inst->copy_range == 0
                || inst->copy_range > skb->len)
                  data_len = skb->len;
            else
                  data_len = inst->copy_range;

            size += nla_total_size(data_len);
            UDEBUG("copy_packet, therefore size now %u\n", size);
            break;

      default:
            goto unlock_and_release;
      }

      if (inst->skb &&
          size > skb_tailroom(inst->skb) - sizeof(struct nfgenmsg)) {
            /* either the queue len is too high or we don't have
             * enough room in the skb left. flush to userspace. */
            UDEBUG("flushing old skb\n");

            __nfulnl_flush(inst);
      }

      if (!inst->skb) {
            inst->skb = nfulnl_alloc_skb(inst->nlbufsiz, size);
            if (!inst->skb)
                  goto alloc_failure;
      }

      UDEBUG("qlen %d, qthreshold %d\n", inst->qlen, qthreshold);
      inst->qlen++;

      __build_packet_message(inst, skb, data_len, pf,
                        hooknum, in, out, li, prefix, plen);

      if (inst->qlen >= qthreshold)
            __nfulnl_flush(inst);
      /* timer_pending always called within inst->lock, so there
       * is no chance of a race here */
      else if (!timer_pending(&inst->timer)) {
            instance_get(inst);
            inst->timer.expires = jiffies + (inst->flushtimeout*HZ/100);
            add_timer(&inst->timer);
      }

unlock_and_release:
      spin_unlock_bh(&inst->lock);
      instance_put(inst);
      return;

alloc_failure:
      UDEBUG("error allocating skb\n");
      /* FIXME: statistics */
      goto unlock_and_release;
}

static int
nfulnl_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 nfulnl_instance *inst;
                  struct hlist_head *head = &instance_table[i];

                  hlist_for_each_entry_safe(inst, tmp, t2, head, hlist) {
                        UDEBUG("node = %p\n", inst);
                        if ((n->net == &init_net) &&
                            (n->pid == inst->peer_pid))
                              __instance_destroy(inst);
                  }
            }
            write_unlock_bh(&instances_lock);
      }
      return NOTIFY_DONE;
}

static struct notifier_block nfulnl_rtnl_notifier = {
      .notifier_call    = nfulnl_rcv_nl_event,
};

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

static struct nf_logger nfulnl_logger = {
      .name = "nfnetlink_log",
      .logfn      = &nfulnl_log_packet,
      .me   = THIS_MODULE,
};

static const struct nla_policy nfula_cfg_policy[NFULA_CFG_MAX+1] = {
      [NFULA_CFG_CMD]         = { .len = sizeof(struct nfulnl_msg_config_cmd) },
      [NFULA_CFG_MODE]  = { .len = sizeof(struct nfulnl_msg_config_mode) },
      [NFULA_CFG_TIMEOUT]     = { .type = NLA_U32 },
      [NFULA_CFG_QTHRESH]     = { .type = NLA_U32 },
      [NFULA_CFG_NLBUFSIZ]    = { .type = NLA_U32 },
      [NFULA_CFG_FLAGS] = { .type = NLA_U16 },
};

static int
nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
               struct nlmsghdr *nlh, struct nlattr *nfula[])
{
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int16_t group_num = ntohs(nfmsg->res_id);
      struct nfulnl_instance *inst;
      int ret = 0;

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

      inst = instance_lookup_get(group_num);
      if (nfula[NFULA_CFG_CMD]) {
            u_int8_t pf = nfmsg->nfgen_family;
            struct nfulnl_msg_config_cmd *cmd;
            cmd = nla_data(nfula[NFULA_CFG_CMD]);
            UDEBUG("found CFG_CMD for\n");

            switch (cmd->command) {
            case NFULNL_CFG_CMD_BIND:
                  if (inst) {
                        ret = -EBUSY;
                        goto out_put;
                  }

                  inst = instance_create(group_num,
                                     NETLINK_CB(skb).pid);
                  if (!inst) {
                        ret = -EINVAL;
                        goto out;
                  }
                  break;
            case NFULNL_CFG_CMD_UNBIND:
                  if (!inst) {
                        ret = -ENODEV;
                        goto out;
                  }

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

                  instance_destroy(inst);
                  goto out;
            case NFULNL_CFG_CMD_PF_BIND:
                  UDEBUG("registering log handler for pf=%u\n", pf);
                  ret = nf_log_register(pf, &nfulnl_logger);
                  break;
            case NFULNL_CFG_CMD_PF_UNBIND:
                  UDEBUG("unregistering log handler for pf=%u\n", pf);
                  /* This is a bug and a feature.  We cannot unregister
                   * other handlers, like nfnetlink_inst can */
                  nf_log_unregister_pf(pf);
                  break;
            default:
                  ret = -EINVAL;
                  break;
            }

            if (!inst)
                  goto out;
      } else {
            if (!inst) {
                  UDEBUG("no config command, and no instance for "
                        "group=%u pid=%u =>ENOENT\n",
                        group_num, NETLINK_CB(skb).pid);
                  ret = -ENOENT;
                  goto out;
            }

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

      if (nfula[NFULA_CFG_MODE]) {
            struct nfulnl_msg_config_mode *params;
            params = nla_data(nfula[NFULA_CFG_MODE]);

            nfulnl_set_mode(inst, params->copy_mode,
                        ntohl(params->copy_range));
      }

      if (nfula[NFULA_CFG_TIMEOUT]) {
            __be32 timeout =
                  *(__be32 *)nla_data(nfula[NFULA_CFG_TIMEOUT]);

            nfulnl_set_timeout(inst, ntohl(timeout));
      }

      if (nfula[NFULA_CFG_NLBUFSIZ]) {
            __be32 nlbufsiz =
                  *(__be32 *)nla_data(nfula[NFULA_CFG_NLBUFSIZ]);

            nfulnl_set_nlbufsiz(inst, ntohl(nlbufsiz));
      }

      if (nfula[NFULA_CFG_QTHRESH]) {
            __be32 qthresh =
                  *(__be32 *)nla_data(nfula[NFULA_CFG_QTHRESH]);

            nfulnl_set_qthresh(inst, ntohl(qthresh));
      }

      if (nfula[NFULA_CFG_FLAGS]) {
            __be16 flags =
                  *(__be16 *)nla_data(nfula[NFULA_CFG_FLAGS]);
            nfulnl_set_flags(inst, ntohs(flags));
      }

out_put:
      instance_put(inst);
out:
      return ret;
}

static const struct nfnl_callback nfulnl_cb[NFULNL_MSG_MAX] = {
      [NFULNL_MSG_PACKET]     = { .call = nfulnl_recv_unsupp,
                            .attr_count = NFULA_MAX, },
      [NFULNL_MSG_CONFIG]     = { .call = nfulnl_recv_config,
                            .attr_count = NFULA_CFG_MAX,
                            .policy = nfula_cfg_policy },
};

static const struct nfnetlink_subsystem nfulnl_subsys = {
      .name       = "log",
      .subsys_id  = NFNL_SUBSYS_ULOG,
      .cb_count   = NFULNL_MSG_MAX,
      .cb         = nfulnl_cb,
};

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

static struct hlist_node *get_first(struct iter_state *st)
{
      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 iter_state *st, struct hlist_node *h)
{
      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 iter_state *st, loff_t pos)
{
      struct hlist_node *head;
      head = get_first(st);

      if (head)
            while (pos && (head = get_next(st, 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->private, *pos);
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
      (*pos)++;
      return get_next(s->private, 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 nfulnl_instance *inst = v;

      return seq_printf(s, "%5d %6d %5d %1d %5d %6d %2d\n",
                    inst->group_num,
                    inst->peer_pid, inst->qlen,
                    inst->copy_mode, inst->copy_range,
                    inst->flushtimeout, atomic_read(&inst->use));
}

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

static int nful_open(struct inode *inode, struct file *file)
{
      return seq_open_private(file, &nful_seq_ops,
                  sizeof(struct iter_state));
}

static const struct file_operations nful_file_ops = {
      .owner       = THIS_MODULE,
      .open  = nful_open,
      .read  = seq_read,
      .llseek      = seq_lseek,
      .release = seq_release_private,
};

#endif /* PROC_FS */

static int __init nfnetlink_log_init(void)
{
      int i, status = -ENOMEM;
#ifdef CONFIG_PROC_FS
      struct proc_dir_entry *proc_nful;
#endif

      for (i = 0; i < INSTANCE_BUCKETS; i++)
            INIT_HLIST_HEAD(&instance_table[i]);

      /* it's not really all that important to have a random value, so
       * we can do this from the init function, even if there hasn't
       * been that much entropy yet */
      get_random_bytes(&hash_init, sizeof(hash_init));

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

#ifdef CONFIG_PROC_FS
      proc_nful = create_proc_entry("nfnetlink_log", 0440,
                              proc_net_netfilter);
      if (!proc_nful)
            goto cleanup_subsys;
      proc_nful->proc_fops = &nful_file_ops;
#endif
      return status;

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

static void __exit nfnetlink_log_fini(void)
{
      nf_log_unregister(&nfulnl_logger);
#ifdef CONFIG_PROC_FS
      remove_proc_entry("nfnetlink_log", proc_net_netfilter);
#endif
      nfnetlink_subsys_unregister(&nfulnl_subsys);
      netlink_unregister_notifier(&nfulnl_rtnl_notifier);
}

MODULE_DESCRIPTION("netfilter userspace logging");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ULOG);

module_init(nfnetlink_log_init);
module_exit(nfnetlink_log_fini);

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