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nf_conntrack_netlink.c

/* Connection tracking via netlink socket. Allows for user space
 * protocol helpers and general trouble making from userspace.
 *
 * (C) 2001 by Jay Schulist <jschlst@samba.org>
 * (C) 2002-2006 by Harald Welte <laforge@gnumonks.org>
 * (C) 2003 by Patrick Mchardy <kaber@trash.net>
 * (C) 2005-2007 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * Initial connection tracking via netlink development funded and
 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
 *
 * Further development of this code funded by Astaro AG (http://www.astaro.com)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <linux/netlink.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>

#include <linux/netfilter.h>
#include <net/netlink.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_l3proto.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#ifdef CONFIG_NF_NAT_NEEDED
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_protocol.h>
#endif

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>

MODULE_LICENSE("GPL");

static char __initdata version[] = "0.93";

static inline int
ctnetlink_dump_tuples_proto(struct sk_buff *skb,
                      const struct nf_conntrack_tuple *tuple,
                      struct nf_conntrack_l4proto *l4proto)
{
      int ret = 0;
      struct nlattr *nest_parms;

      nest_parms = nla_nest_start(skb, CTA_TUPLE_PROTO | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;
      NLA_PUT(skb, CTA_PROTO_NUM, sizeof(u_int8_t), &tuple->dst.protonum);

      if (likely(l4proto->tuple_to_nlattr))
            ret = l4proto->tuple_to_nlattr(skb, tuple);

      nla_nest_end(skb, nest_parms);

      return ret;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_dump_tuples_ip(struct sk_buff *skb,
                   const struct nf_conntrack_tuple *tuple,
                   struct nf_conntrack_l3proto *l3proto)
{
      int ret = 0;
      struct nlattr *nest_parms;

      nest_parms = nla_nest_start(skb, CTA_TUPLE_IP | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;

      if (likely(l3proto->tuple_to_nlattr))
            ret = l3proto->tuple_to_nlattr(skb, tuple);

      nla_nest_end(skb, nest_parms);

      return ret;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_dump_tuples(struct sk_buff *skb,
                  const struct nf_conntrack_tuple *tuple)
{
      int ret;
      struct nf_conntrack_l3proto *l3proto;
      struct nf_conntrack_l4proto *l4proto;

      l3proto = nf_ct_l3proto_find_get(tuple->src.l3num);
      ret = ctnetlink_dump_tuples_ip(skb, tuple, l3proto);
      nf_ct_l3proto_put(l3proto);

      if (unlikely(ret < 0))
            return ret;

      l4proto = nf_ct_l4proto_find_get(tuple->src.l3num, tuple->dst.protonum);
      ret = ctnetlink_dump_tuples_proto(skb, tuple, l4proto);
      nf_ct_l4proto_put(l4proto);

      return ret;
}

static inline int
ctnetlink_dump_status(struct sk_buff *skb, const struct nf_conn *ct)
{
      __be32 status = htonl((u_int32_t) ct->status);
      NLA_PUT(skb, CTA_STATUS, sizeof(status), &status);
      return 0;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_dump_timeout(struct sk_buff *skb, const struct nf_conn *ct)
{
      long timeout_l = ct->timeout.expires - jiffies;
      __be32 timeout;

      if (timeout_l < 0)
            timeout = 0;
      else
            timeout = htonl(timeout_l / HZ);

      NLA_PUT(skb, CTA_TIMEOUT, sizeof(timeout), &timeout);
      return 0;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_dump_protoinfo(struct sk_buff *skb, const struct nf_conn *ct)
{
      struct nf_conntrack_l4proto *l4proto = nf_ct_l4proto_find_get(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num, ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum);
      struct nlattr *nest_proto;
      int ret;

      if (!l4proto->to_nlattr) {
            nf_ct_l4proto_put(l4proto);
            return 0;
      }

      nest_proto = nla_nest_start(skb, CTA_PROTOINFO | NLA_F_NESTED);
      if (!nest_proto)
            goto nla_put_failure;

      ret = l4proto->to_nlattr(skb, nest_proto, ct);

      nf_ct_l4proto_put(l4proto);

      nla_nest_end(skb, nest_proto);

      return ret;

nla_put_failure:
      nf_ct_l4proto_put(l4proto);
      return -1;
}

static inline int
ctnetlink_dump_helpinfo(struct sk_buff *skb, const struct nf_conn *ct)
{
      struct nlattr *nest_helper;
      const struct nf_conn_help *help = nfct_help(ct);
      struct nf_conntrack_helper *helper;

      if (!help)
            return 0;

      rcu_read_lock();
      helper = rcu_dereference(help->helper);
      if (!helper)
            goto out;

      nest_helper = nla_nest_start(skb, CTA_HELP | NLA_F_NESTED);
      if (!nest_helper)
            goto nla_put_failure;
      NLA_PUT(skb, CTA_HELP_NAME, strlen(helper->name), helper->name);

      if (helper->to_nlattr)
            helper->to_nlattr(skb, ct);

      nla_nest_end(skb, nest_helper);
out:
      rcu_read_unlock();
      return 0;

nla_put_failure:
      rcu_read_unlock();
      return -1;
}

#ifdef CONFIG_NF_CT_ACCT
static inline int
ctnetlink_dump_counters(struct sk_buff *skb, const struct nf_conn *ct,
                  enum ip_conntrack_dir dir)
{
      enum ctattr_type type = dir ? CTA_COUNTERS_REPLY: CTA_COUNTERS_ORIG;
      struct nlattr *nest_count;
      __be32 tmp;

      nest_count = nla_nest_start(skb, type | NLA_F_NESTED);
      if (!nest_count)
            goto nla_put_failure;

      tmp = htonl(ct->counters[dir].packets);
      NLA_PUT(skb, CTA_COUNTERS32_PACKETS, sizeof(u_int32_t), &tmp);

      tmp = htonl(ct->counters[dir].bytes);
      NLA_PUT(skb, CTA_COUNTERS32_BYTES, sizeof(u_int32_t), &tmp);

      nla_nest_end(skb, nest_count);

      return 0;

nla_put_failure:
      return -1;
}
#else
#define ctnetlink_dump_counters(a, b, c) (0)
#endif

#ifdef CONFIG_NF_CONNTRACK_MARK
static inline int
ctnetlink_dump_mark(struct sk_buff *skb, const struct nf_conn *ct)
{
      __be32 mark = htonl(ct->mark);

      NLA_PUT(skb, CTA_MARK, sizeof(u_int32_t), &mark);
      return 0;

nla_put_failure:
      return -1;
}
#else
#define ctnetlink_dump_mark(a, b) (0)
#endif

static inline int
ctnetlink_dump_id(struct sk_buff *skb, const struct nf_conn *ct)
{
      __be32 id = htonl((unsigned long)ct);
      NLA_PUT(skb, CTA_ID, sizeof(u_int32_t), &id);
      return 0;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_dump_use(struct sk_buff *skb, const struct nf_conn *ct)
{
      __be32 use = htonl(atomic_read(&ct->ct_general.use));

      NLA_PUT(skb, CTA_USE, sizeof(u_int32_t), &use);
      return 0;

nla_put_failure:
      return -1;
}

#define tuple(ct, dir) (&(ct)->tuplehash[dir].tuple)

static int
ctnetlink_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
                int event, int nowait,
                const struct nf_conn *ct)
{
      struct nlmsghdr *nlh;
      struct nfgenmsg *nfmsg;
      struct nlattr *nest_parms;
      unsigned char *b = skb_tail_pointer(skb);

      event |= NFNL_SUBSYS_CTNETLINK << 8;
      nlh    = NLMSG_PUT(skb, pid, seq, event, sizeof(struct nfgenmsg));
      nfmsg  = NLMSG_DATA(nlh);

      nlh->nlmsg_flags    = (nowait && pid) ? NLM_F_MULTI : 0;
      nfmsg->nfgen_family =
            ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
      nfmsg->version      = NFNETLINK_V0;
      nfmsg->res_id         = 0;

      nest_parms = nla_nest_start(skb, CTA_TUPLE_ORIG | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;
      if (ctnetlink_dump_tuples(skb, tuple(ct, IP_CT_DIR_ORIGINAL)) < 0)
            goto nla_put_failure;
      nla_nest_end(skb, nest_parms);

      nest_parms = nla_nest_start(skb, CTA_TUPLE_REPLY | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;
      if (ctnetlink_dump_tuples(skb, tuple(ct, IP_CT_DIR_REPLY)) < 0)
            goto nla_put_failure;
      nla_nest_end(skb, nest_parms);

      if (ctnetlink_dump_status(skb, ct) < 0 ||
          ctnetlink_dump_timeout(skb, ct) < 0 ||
          ctnetlink_dump_counters(skb, ct, IP_CT_DIR_ORIGINAL) < 0 ||
          ctnetlink_dump_counters(skb, ct, IP_CT_DIR_REPLY) < 0 ||
          ctnetlink_dump_protoinfo(skb, ct) < 0 ||
          ctnetlink_dump_helpinfo(skb, ct) < 0 ||
          ctnetlink_dump_mark(skb, ct) < 0 ||
          ctnetlink_dump_id(skb, ct) < 0 ||
          ctnetlink_dump_use(skb, ct) < 0)
            goto nla_put_failure;

      nlh->nlmsg_len = skb_tail_pointer(skb) - b;
      return skb->len;

nlmsg_failure:
nla_put_failure:
      nlmsg_trim(skb, b);
      return -1;
}

#ifdef CONFIG_NF_CONNTRACK_EVENTS
static int ctnetlink_conntrack_event(struct notifier_block *this,
                             unsigned long events, void *ptr)
{
      struct nlmsghdr *nlh;
      struct nfgenmsg *nfmsg;
      struct nlattr *nest_parms;
      struct nf_conn *ct = (struct nf_conn *)ptr;
      struct sk_buff *skb;
      unsigned int type;
      sk_buff_data_t b;
      unsigned int flags = 0, group;

      /* ignore our fake conntrack entry */
      if (ct == &nf_conntrack_untracked)
            return NOTIFY_DONE;

      if (events & IPCT_DESTROY) {
            type = IPCTNL_MSG_CT_DELETE;
            group = NFNLGRP_CONNTRACK_DESTROY;
      } else  if (events & (IPCT_NEW | IPCT_RELATED)) {
            type = IPCTNL_MSG_CT_NEW;
            flags = NLM_F_CREATE|NLM_F_EXCL;
            group = NFNLGRP_CONNTRACK_NEW;
      } else  if (events & (IPCT_STATUS | IPCT_PROTOINFO)) {
            type = IPCTNL_MSG_CT_NEW;
            group = NFNLGRP_CONNTRACK_UPDATE;
      } else
            return NOTIFY_DONE;

      if (!nfnetlink_has_listeners(group))
            return NOTIFY_DONE;

      skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
      if (!skb)
            return NOTIFY_DONE;

      b = skb->tail;

      type |= NFNL_SUBSYS_CTNETLINK << 8;
      nlh   = NLMSG_PUT(skb, 0, 0, type, sizeof(struct nfgenmsg));
      nfmsg = NLMSG_DATA(nlh);

      nlh->nlmsg_flags    = flags;
      nfmsg->nfgen_family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
      nfmsg->version    = NFNETLINK_V0;
      nfmsg->res_id     = 0;

      nest_parms = nla_nest_start(skb, CTA_TUPLE_ORIG | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;
      if (ctnetlink_dump_tuples(skb, tuple(ct, IP_CT_DIR_ORIGINAL)) < 0)
            goto nla_put_failure;
      nla_nest_end(skb, nest_parms);

      nest_parms = nla_nest_start(skb, CTA_TUPLE_REPLY | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;
      if (ctnetlink_dump_tuples(skb, tuple(ct, IP_CT_DIR_REPLY)) < 0)
            goto nla_put_failure;
      nla_nest_end(skb, nest_parms);

      if (events & IPCT_DESTROY) {
            if (ctnetlink_dump_counters(skb, ct, IP_CT_DIR_ORIGINAL) < 0 ||
                ctnetlink_dump_counters(skb, ct, IP_CT_DIR_REPLY) < 0)
                  goto nla_put_failure;
      } else {
            if (ctnetlink_dump_status(skb, ct) < 0)
                  goto nla_put_failure;

            if (ctnetlink_dump_timeout(skb, ct) < 0)
                  goto nla_put_failure;

            if (events & IPCT_PROTOINFO
                && ctnetlink_dump_protoinfo(skb, ct) < 0)
                  goto nla_put_failure;

            if ((events & IPCT_HELPER || nfct_help(ct))
                && ctnetlink_dump_helpinfo(skb, ct) < 0)
                  goto nla_put_failure;

#ifdef CONFIG_NF_CONNTRACK_MARK
            if ((events & IPCT_MARK || ct->mark)
                && ctnetlink_dump_mark(skb, ct) < 0)
                  goto nla_put_failure;
#endif

            if (events & IPCT_COUNTER_FILLING &&
                (ctnetlink_dump_counters(skb, ct, IP_CT_DIR_ORIGINAL) < 0 ||
                 ctnetlink_dump_counters(skb, ct, IP_CT_DIR_REPLY) < 0))
                  goto nla_put_failure;
      }

      nlh->nlmsg_len = skb->tail - b;
      nfnetlink_send(skb, 0, group, 0);
      return NOTIFY_DONE;

nlmsg_failure:
nla_put_failure:
      kfree_skb(skb);
      return NOTIFY_DONE;
}
#endif /* CONFIG_NF_CONNTRACK_EVENTS */

static int ctnetlink_done(struct netlink_callback *cb)
{
      if (cb->args[1])
            nf_ct_put((struct nf_conn *)cb->args[1]);
      return 0;
}

#define L3PROTO(ct) ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num

static int
ctnetlink_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
{
      struct nf_conn *ct, *last;
      struct nf_conntrack_tuple_hash *h;
      struct hlist_node *n;
      struct nfgenmsg *nfmsg = NLMSG_DATA(cb->nlh);
      u_int8_t l3proto = nfmsg->nfgen_family;

      read_lock_bh(&nf_conntrack_lock);
      last = (struct nf_conn *)cb->args[1];
      for (; cb->args[0] < nf_conntrack_htable_size; cb->args[0]++) {
restart:
            hlist_for_each_entry(h, n, &nf_conntrack_hash[cb->args[0]],
                             hnode) {
                  if (NF_CT_DIRECTION(h) != IP_CT_DIR_ORIGINAL)
                        continue;
                  ct = nf_ct_tuplehash_to_ctrack(h);
                  /* Dump entries of a given L3 protocol number.
                   * If it is not specified, ie. l3proto == 0,
                   * then dump everything. */
                  if (l3proto && L3PROTO(ct) != l3proto)
                        continue;
                  if (cb->args[1]) {
                        if (ct != last)
                              continue;
                        cb->args[1] = 0;
                  }
                  if (ctnetlink_fill_info(skb, NETLINK_CB(cb->skb).pid,
                                    cb->nlh->nlmsg_seq,
                                    IPCTNL_MSG_CT_NEW,
                                    1, ct) < 0) {
                        nf_conntrack_get(&ct->ct_general);
                        cb->args[1] = (unsigned long)ct;
                        goto out;
                  }
#ifdef CONFIG_NF_CT_ACCT
                  if (NFNL_MSG_TYPE(cb->nlh->nlmsg_type) ==
                                    IPCTNL_MSG_CT_GET_CTRZERO)
                        memset(&ct->counters, 0, sizeof(ct->counters));
#endif
            }
            if (cb->args[1]) {
                  cb->args[1] = 0;
                  goto restart;
            }
      }
out:
      read_unlock_bh(&nf_conntrack_lock);
      if (last)
            nf_ct_put(last);

      return skb->len;
}

static inline int
ctnetlink_parse_tuple_ip(struct nlattr *attr, struct nf_conntrack_tuple *tuple)
{
      struct nlattr *tb[CTA_IP_MAX+1];
      struct nf_conntrack_l3proto *l3proto;
      int ret = 0;

      nla_parse_nested(tb, CTA_IP_MAX, attr, NULL);

      l3proto = nf_ct_l3proto_find_get(tuple->src.l3num);

      if (likely(l3proto->nlattr_to_tuple)) {
            ret = nla_validate_nested(attr, CTA_IP_MAX,
                                l3proto->nla_policy);
            if (ret == 0)
                  ret = l3proto->nlattr_to_tuple(tb, tuple);
      }

      nf_ct_l3proto_put(l3proto);

      return ret;
}

static const struct nla_policy proto_nla_policy[CTA_PROTO_MAX+1] = {
      [CTA_PROTO_NUM]   = { .type = NLA_U8 },
};

static inline int
ctnetlink_parse_tuple_proto(struct nlattr *attr,
                      struct nf_conntrack_tuple *tuple)
{
      struct nlattr *tb[CTA_PROTO_MAX+1];
      struct nf_conntrack_l4proto *l4proto;
      int ret = 0;

      ret = nla_parse_nested(tb, CTA_PROTO_MAX, attr, proto_nla_policy);
      if (ret < 0)
            return ret;

      if (!tb[CTA_PROTO_NUM])
            return -EINVAL;
      tuple->dst.protonum = *(u_int8_t *)nla_data(tb[CTA_PROTO_NUM]);

      l4proto = nf_ct_l4proto_find_get(tuple->src.l3num, tuple->dst.protonum);

      if (likely(l4proto->nlattr_to_tuple)) {
            ret = nla_validate_nested(attr, CTA_PROTO_MAX,
                                l4proto->nla_policy);
            if (ret == 0)
                  ret = l4proto->nlattr_to_tuple(tb, tuple);
      }

      nf_ct_l4proto_put(l4proto);

      return ret;
}

static inline int
ctnetlink_parse_tuple(struct nlattr *cda[], struct nf_conntrack_tuple *tuple,
                  enum ctattr_tuple type, u_int8_t l3num)
{
      struct nlattr *tb[CTA_TUPLE_MAX+1];
      int err;

      memset(tuple, 0, sizeof(*tuple));

      nla_parse_nested(tb, CTA_TUPLE_MAX, cda[type], NULL);

      if (!tb[CTA_TUPLE_IP])
            return -EINVAL;

      tuple->src.l3num = l3num;

      err = ctnetlink_parse_tuple_ip(tb[CTA_TUPLE_IP], tuple);
      if (err < 0)
            return err;

      if (!tb[CTA_TUPLE_PROTO])
            return -EINVAL;

      err = ctnetlink_parse_tuple_proto(tb[CTA_TUPLE_PROTO], tuple);
      if (err < 0)
            return err;

      /* orig and expect tuples get DIR_ORIGINAL */
      if (type == CTA_TUPLE_REPLY)
            tuple->dst.dir = IP_CT_DIR_REPLY;
      else
            tuple->dst.dir = IP_CT_DIR_ORIGINAL;

      return 0;
}

#ifdef CONFIG_NF_NAT_NEEDED
static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
      [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
      [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
};

static int nfnetlink_parse_nat_proto(struct nlattr *attr,
                             const struct nf_conn *ct,
                             struct nf_nat_range *range)
{
      struct nlattr *tb[CTA_PROTONAT_MAX+1];
      struct nf_nat_protocol *npt;
      int err;

      err = nla_parse_nested(tb, CTA_PROTONAT_MAX, attr, protonat_nla_policy);
      if (err < 0)
            return err;

      npt = nf_nat_proto_find_get(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum);

      if (!npt->nlattr_to_range) {
            nf_nat_proto_put(npt);
            return 0;
      }

      /* nlattr_to_range returns 1 if it parsed, 0 if not, neg. on error */
      if (npt->nlattr_to_range(tb, range) > 0)
            range->flags |= IP_NAT_RANGE_PROTO_SPECIFIED;

      nf_nat_proto_put(npt);

      return 0;
}

static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
      [CTA_NAT_MINIP]         = { .type = NLA_U32 },
      [CTA_NAT_MAXIP]         = { .type = NLA_U32 },
};

static inline int
nfnetlink_parse_nat(struct nlattr *nat,
                const struct nf_conn *ct, struct nf_nat_range *range)
{
      struct nlattr *tb[CTA_NAT_MAX+1];
      int err;

      memset(range, 0, sizeof(*range));

      err = nla_parse_nested(tb, CTA_NAT_MAX, nat, nat_nla_policy);
      if (err < 0)
            return err;

      if (tb[CTA_NAT_MINIP])
            range->min_ip = *(__be32 *)nla_data(tb[CTA_NAT_MINIP]);

      if (!tb[CTA_NAT_MAXIP])
            range->max_ip = range->min_ip;
      else
            range->max_ip = *(__be32 *)nla_data(tb[CTA_NAT_MAXIP]);

      if (range->min_ip)
            range->flags |= IP_NAT_RANGE_MAP_IPS;

      if (!tb[CTA_NAT_PROTO])
            return 0;

      err = nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
      if (err < 0)
            return err;

      return 0;
}
#endif

static inline int
ctnetlink_parse_help(struct nlattr *attr, char **helper_name)
{
      struct nlattr *tb[CTA_HELP_MAX+1];

      nla_parse_nested(tb, CTA_HELP_MAX, attr, NULL);

      if (!tb[CTA_HELP_NAME])
            return -EINVAL;

      *helper_name = nla_data(tb[CTA_HELP_NAME]);

      return 0;
}

static const struct nla_policy ct_nla_policy[CTA_MAX+1] = {
      [CTA_STATUS]            = { .type = NLA_U32 },
      [CTA_TIMEOUT]           = { .type = NLA_U32 },
      [CTA_MARK]        = { .type = NLA_U32 },
      [CTA_USE]         = { .type = NLA_U32 },
      [CTA_ID]          = { .type = NLA_U32 },
};

static int
ctnetlink_del_conntrack(struct sock *ctnl, struct sk_buff *skb,
                  struct nlmsghdr *nlh, struct nlattr *cda[])
{
      struct nf_conntrack_tuple_hash *h;
      struct nf_conntrack_tuple tuple;
      struct nf_conn *ct;
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int8_t u3 = nfmsg->nfgen_family;
      int err = 0;

      if (cda[CTA_TUPLE_ORIG])
            err = ctnetlink_parse_tuple(cda, &tuple, CTA_TUPLE_ORIG, u3);
      else if (cda[CTA_TUPLE_REPLY])
            err = ctnetlink_parse_tuple(cda, &tuple, CTA_TUPLE_REPLY, u3);
      else {
            /* Flush the whole table */
            nf_conntrack_flush();
            return 0;
      }

      if (err < 0)
            return err;

      h = nf_conntrack_find_get(&tuple);
      if (!h)
            return -ENOENT;

      ct = nf_ct_tuplehash_to_ctrack(h);

      if (cda[CTA_ID]) {
            u_int32_t id = ntohl(*(__be32 *)nla_data(cda[CTA_ID]));
            if (id != (u32)(unsigned long)ct) {
                  nf_ct_put(ct);
                  return -ENOENT;
            }
      }
      if (del_timer(&ct->timeout))
            ct->timeout.function((unsigned long)ct);

      nf_ct_put(ct);

      return 0;
}

static int
ctnetlink_get_conntrack(struct sock *ctnl, struct sk_buff *skb,
                  struct nlmsghdr *nlh, struct nlattr *cda[])
{
      struct nf_conntrack_tuple_hash *h;
      struct nf_conntrack_tuple tuple;
      struct nf_conn *ct;
      struct sk_buff *skb2 = NULL;
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int8_t u3 = nfmsg->nfgen_family;
      int err = 0;

      if (nlh->nlmsg_flags & NLM_F_DUMP) {
#ifndef CONFIG_NF_CT_ACCT
            if (NFNL_MSG_TYPE(nlh->nlmsg_type) == IPCTNL_MSG_CT_GET_CTRZERO)
                  return -ENOTSUPP;
#endif
            return netlink_dump_start(ctnl, skb, nlh, ctnetlink_dump_table,
                                ctnetlink_done);
      }

      if (cda[CTA_TUPLE_ORIG])
            err = ctnetlink_parse_tuple(cda, &tuple, CTA_TUPLE_ORIG, u3);
      else if (cda[CTA_TUPLE_REPLY])
            err = ctnetlink_parse_tuple(cda, &tuple, CTA_TUPLE_REPLY, u3);
      else
            return -EINVAL;

      if (err < 0)
            return err;

      h = nf_conntrack_find_get(&tuple);
      if (!h)
            return -ENOENT;

      ct = nf_ct_tuplehash_to_ctrack(h);

      err = -ENOMEM;
      skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
      if (!skb2) {
            nf_ct_put(ct);
            return -ENOMEM;
      }

      err = ctnetlink_fill_info(skb2, NETLINK_CB(skb).pid, nlh->nlmsg_seq,
                          IPCTNL_MSG_CT_NEW, 1, ct);
      nf_ct_put(ct);
      if (err <= 0)
            goto free;

      err = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
      if (err < 0)
            goto out;

      return 0;

free:
      kfree_skb(skb2);
out:
      return err;
}

static inline int
ctnetlink_change_status(struct nf_conn *ct, struct nlattr *cda[])
{
      unsigned long d;
      unsigned int status = ntohl(*(__be32 *)nla_data(cda[CTA_STATUS]));
      d = ct->status ^ status;

      if (d & (IPS_EXPECTED|IPS_CONFIRMED|IPS_DYING))
            /* unchangeable */
            return -EINVAL;

      if (d & IPS_SEEN_REPLY && !(status & IPS_SEEN_REPLY))
            /* SEEN_REPLY bit can only be set */
            return -EINVAL;


      if (d & IPS_ASSURED && !(status & IPS_ASSURED))
            /* ASSURED bit can only be set */
            return -EINVAL;

      if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) {
#ifndef CONFIG_NF_NAT_NEEDED
            return -EINVAL;
#else
            struct nf_nat_range range;

            if (cda[CTA_NAT_DST]) {
                  if (nfnetlink_parse_nat(cda[CTA_NAT_DST], ct,
                                    &range) < 0)
                        return -EINVAL;
                  if (nf_nat_initialized(ct,
                                     HOOK2MANIP(NF_IP_PRE_ROUTING)))
                        return -EEXIST;
                  nf_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING);
            }
            if (cda[CTA_NAT_SRC]) {
                  if (nfnetlink_parse_nat(cda[CTA_NAT_SRC], ct,
                                    &range) < 0)
                        return -EINVAL;
                  if (nf_nat_initialized(ct,
                                     HOOK2MANIP(NF_IP_POST_ROUTING)))
                        return -EEXIST;
                  nf_nat_setup_info(ct, &range, NF_IP_POST_ROUTING);
            }
#endif
      }

      /* Be careful here, modifying NAT bits can screw up things,
       * so don't let users modify them directly if they don't pass
       * nf_nat_range. */
      ct->status |= status & ~(IPS_NAT_DONE_MASK | IPS_NAT_MASK);
      return 0;
}


static inline int
ctnetlink_change_helper(struct nf_conn *ct, struct nlattr *cda[])
{
      struct nf_conntrack_helper *helper;
      struct nf_conn_help *help = nfct_help(ct);
      char *helpname;
      int err;

      /* don't change helper of sibling connections */
      if (ct->master)
            return -EINVAL;

      err = ctnetlink_parse_help(cda[CTA_HELP], &helpname);
      if (err < 0)
            return err;

      if (!strcmp(helpname, "")) {
            if (help && help->helper) {
                  /* we had a helper before ... */
                  nf_ct_remove_expectations(ct);
                  rcu_assign_pointer(help->helper, NULL);
            }

            return 0;
      }

      helper = __nf_conntrack_helper_find_byname(helpname);
      if (helper == NULL)
            return -EINVAL;

      if (help) {
            if (help->helper == helper)
                  return 0;
            if (help->helper)
                  return -EBUSY;
            /* need to zero data of old helper */
            memset(&help->help, 0, sizeof(help->help));
      } else {
            help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
            if (help == NULL)
                  return -ENOMEM;
      }

      rcu_assign_pointer(help->helper, helper);

      return 0;
}

static inline int
ctnetlink_change_timeout(struct nf_conn *ct, struct nlattr *cda[])
{
      u_int32_t timeout = ntohl(*(__be32 *)nla_data(cda[CTA_TIMEOUT]));

      if (!del_timer(&ct->timeout))
            return -ETIME;

      ct->timeout.expires = jiffies + timeout * HZ;
      add_timer(&ct->timeout);

      return 0;
}

static inline int
ctnetlink_change_protoinfo(struct nf_conn *ct, struct nlattr *cda[])
{
      struct nlattr *tb[CTA_PROTOINFO_MAX+1], *attr = cda[CTA_PROTOINFO];
      struct nf_conntrack_l4proto *l4proto;
      u_int16_t npt = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum;
      u_int16_t l3num = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
      int err = 0;

      nla_parse_nested(tb, CTA_PROTOINFO_MAX, attr, NULL);

      l4proto = nf_ct_l4proto_find_get(l3num, npt);

      if (l4proto->from_nlattr)
            err = l4proto->from_nlattr(tb, ct);
      nf_ct_l4proto_put(l4proto);

      return err;
}

static int
ctnetlink_change_conntrack(struct nf_conn *ct, struct nlattr *cda[])
{
      int err;

      if (cda[CTA_HELP]) {
            err = ctnetlink_change_helper(ct, cda);
            if (err < 0)
                  return err;
      }

      if (cda[CTA_TIMEOUT]) {
            err = ctnetlink_change_timeout(ct, cda);
            if (err < 0)
                  return err;
      }

      if (cda[CTA_STATUS]) {
            err = ctnetlink_change_status(ct, cda);
            if (err < 0)
                  return err;
      }

      if (cda[CTA_PROTOINFO]) {
            err = ctnetlink_change_protoinfo(ct, cda);
            if (err < 0)
                  return err;
      }

#if defined(CONFIG_NF_CONNTRACK_MARK)
      if (cda[CTA_MARK])
            ct->mark = ntohl(*(__be32 *)nla_data(cda[CTA_MARK]));
#endif

      return 0;
}

static int
ctnetlink_create_conntrack(struct nlattr *cda[],
                     struct nf_conntrack_tuple *otuple,
                     struct nf_conntrack_tuple *rtuple,
                     struct nf_conn *master_ct)
{
      struct nf_conn *ct;
      int err = -EINVAL;
      struct nf_conn_help *help;
      struct nf_conntrack_helper *helper;

      ct = nf_conntrack_alloc(otuple, rtuple);
      if (ct == NULL || IS_ERR(ct))
            return -ENOMEM;

      if (!cda[CTA_TIMEOUT])
            goto err;
      ct->timeout.expires = ntohl(*(__be32 *)nla_data(cda[CTA_TIMEOUT]));

      ct->timeout.expires = jiffies + ct->timeout.expires * HZ;
      ct->status |= IPS_CONFIRMED;

      if (cda[CTA_STATUS]) {
            err = ctnetlink_change_status(ct, cda);
            if (err < 0)
                  goto err;
      }

      if (cda[CTA_PROTOINFO]) {
            err = ctnetlink_change_protoinfo(ct, cda);
            if (err < 0)
                  goto err;
      }

#if defined(CONFIG_NF_CONNTRACK_MARK)
      if (cda[CTA_MARK])
            ct->mark = ntohl(*(__be32 *)nla_data(cda[CTA_MARK]));
#endif

      helper = nf_ct_helper_find_get(rtuple);
      if (helper) {
            help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
            if (help == NULL) {
                  nf_ct_helper_put(helper);
                  err = -ENOMEM;
                  goto err;
            }
            /* not in hash table yet so not strictly necessary */
            rcu_assign_pointer(help->helper, helper);
      }

      /* setup master conntrack: this is a confirmed expectation */
      if (master_ct) {
            __set_bit(IPS_EXPECTED_BIT, &ct->status);
            ct->master = master_ct;
      }

      add_timer(&ct->timeout);
      nf_conntrack_hash_insert(ct);

      if (helper)
            nf_ct_helper_put(helper);

      return 0;

err:
      nf_conntrack_free(ct);
      return err;
}

static int
ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
                  struct nlmsghdr *nlh, struct nlattr *cda[])
{
      struct nf_conntrack_tuple otuple, rtuple;
      struct nf_conntrack_tuple_hash *h = NULL;
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int8_t u3 = nfmsg->nfgen_family;
      int err = 0;

      if (cda[CTA_TUPLE_ORIG]) {
            err = ctnetlink_parse_tuple(cda, &otuple, CTA_TUPLE_ORIG, u3);
            if (err < 0)
                  return err;
      }

      if (cda[CTA_TUPLE_REPLY]) {
            err = ctnetlink_parse_tuple(cda, &rtuple, CTA_TUPLE_REPLY, u3);
            if (err < 0)
                  return err;
      }

      write_lock_bh(&nf_conntrack_lock);
      if (cda[CTA_TUPLE_ORIG])
            h = __nf_conntrack_find(&otuple, NULL);
      else if (cda[CTA_TUPLE_REPLY])
            h = __nf_conntrack_find(&rtuple, NULL);

      if (h == NULL) {
            struct nf_conntrack_tuple master;
            struct nf_conntrack_tuple_hash *master_h = NULL;
            struct nf_conn *master_ct = NULL;

            if (cda[CTA_TUPLE_MASTER]) {
                  err = ctnetlink_parse_tuple(cda,
                                        &master,
                                        CTA_TUPLE_MASTER,
                                        u3);
                  if (err < 0)
                        return err;

                  master_h = __nf_conntrack_find(&master, NULL);
                  if (master_h == NULL) {
                        err = -ENOENT;
                        goto out_unlock;
                  }
                  master_ct = nf_ct_tuplehash_to_ctrack(master_h);
                  atomic_inc(&master_ct->ct_general.use);
            }

            write_unlock_bh(&nf_conntrack_lock);
            err = -ENOENT;
            if (nlh->nlmsg_flags & NLM_F_CREATE)
                  err = ctnetlink_create_conntrack(cda,
                                           &otuple,
                                           &rtuple,
                                           master_ct);
            if (err < 0 && master_ct)
                  nf_ct_put(master_ct);

            return err;
      }
      /* implicit 'else' */

      /* We manipulate the conntrack inside the global conntrack table lock,
       * so there's no need to increase the refcount */
      err = -EEXIST;
      if (!(nlh->nlmsg_flags & NLM_F_EXCL)) {
            /* we only allow nat config for new conntracks */
            if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) {
                  err = -EINVAL;
                  goto out_unlock;
            }
            /* can't link an existing conntrack to a master */
            if (cda[CTA_TUPLE_MASTER]) {
                  err = -EINVAL;
                  goto out_unlock;
            }
            err = ctnetlink_change_conntrack(nf_ct_tuplehash_to_ctrack(h),
                                     cda);
      }

out_unlock:
      write_unlock_bh(&nf_conntrack_lock);
      return err;
}

/***********************************************************************
 * EXPECT
 ***********************************************************************/

static inline int
ctnetlink_exp_dump_tuple(struct sk_buff *skb,
                   const struct nf_conntrack_tuple *tuple,
                   enum ctattr_expect type)
{
      struct nlattr *nest_parms;

      nest_parms = nla_nest_start(skb, type | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;
      if (ctnetlink_dump_tuples(skb, tuple) < 0)
            goto nla_put_failure;
      nla_nest_end(skb, nest_parms);

      return 0;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_exp_dump_mask(struct sk_buff *skb,
                  const struct nf_conntrack_tuple *tuple,
                  const struct nf_conntrack_tuple_mask *mask)
{
      int ret;
      struct nf_conntrack_l3proto *l3proto;
      struct nf_conntrack_l4proto *l4proto;
      struct nf_conntrack_tuple m;
      struct nlattr *nest_parms;

      memset(&m, 0xFF, sizeof(m));
      m.src.u.all = mask->src.u.all;
      memcpy(&m.src.u3, &mask->src.u3, sizeof(m.src.u3));

      nest_parms = nla_nest_start(skb, CTA_EXPECT_MASK | NLA_F_NESTED);
      if (!nest_parms)
            goto nla_put_failure;

      l3proto = nf_ct_l3proto_find_get(tuple->src.l3num);
      ret = ctnetlink_dump_tuples_ip(skb, &m, l3proto);
      nf_ct_l3proto_put(l3proto);

      if (unlikely(ret < 0))
            goto nla_put_failure;

      l4proto = nf_ct_l4proto_find_get(tuple->src.l3num, tuple->dst.protonum);
      ret = ctnetlink_dump_tuples_proto(skb, &m, l4proto);
      nf_ct_l4proto_put(l4proto);
      if (unlikely(ret < 0))
            goto nla_put_failure;

      nla_nest_end(skb, nest_parms);

      return 0;

nla_put_failure:
      return -1;
}

static inline int
ctnetlink_exp_dump_expect(struct sk_buff *skb,
                    const struct nf_conntrack_expect *exp)
{
      struct nf_conn *master = exp->master;
      __be32 timeout = htonl((exp->timeout.expires - jiffies) / HZ);
      __be32 id = htonl((unsigned long)exp);

      if (ctnetlink_exp_dump_tuple(skb, &exp->tuple, CTA_EXPECT_TUPLE) < 0)
            goto nla_put_failure;
      if (ctnetlink_exp_dump_mask(skb, &exp->tuple, &exp->mask) < 0)
            goto nla_put_failure;
      if (ctnetlink_exp_dump_tuple(skb,
                         &master->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
                         CTA_EXPECT_MASTER) < 0)
            goto nla_put_failure;

      NLA_PUT(skb, CTA_EXPECT_TIMEOUT, sizeof(timeout), &timeout);
      NLA_PUT(skb, CTA_EXPECT_ID, sizeof(u_int32_t), &id);

      return 0;

nla_put_failure:
      return -1;
}

static int
ctnetlink_exp_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
                int event,
                int nowait,
                const struct nf_conntrack_expect *exp)
{
      struct nlmsghdr *nlh;
      struct nfgenmsg *nfmsg;
      unsigned char *b = skb_tail_pointer(skb);

      event |= NFNL_SUBSYS_CTNETLINK_EXP << 8;
      nlh    = NLMSG_PUT(skb, pid, seq, event, sizeof(struct nfgenmsg));
      nfmsg  = NLMSG_DATA(nlh);

      nlh->nlmsg_flags    = (nowait && pid) ? NLM_F_MULTI : 0;
      nfmsg->nfgen_family = exp->tuple.src.l3num;
      nfmsg->version        = NFNETLINK_V0;
      nfmsg->res_id         = 0;

      if (ctnetlink_exp_dump_expect(skb, exp) < 0)
            goto nla_put_failure;

      nlh->nlmsg_len = skb_tail_pointer(skb) - b;
      return skb->len;

nlmsg_failure:
nla_put_failure:
      nlmsg_trim(skb, b);
      return -1;
}

#ifdef CONFIG_NF_CONNTRACK_EVENTS
static int ctnetlink_expect_event(struct notifier_block *this,
                          unsigned long events, void *ptr)
{
      struct nlmsghdr *nlh;
      struct nfgenmsg *nfmsg;
      struct nf_conntrack_expect *exp = (struct nf_conntrack_expect *)ptr;
      struct sk_buff *skb;
      unsigned int type;
      sk_buff_data_t b;
      int flags = 0;

      if (events & IPEXP_NEW) {
            type = IPCTNL_MSG_EXP_NEW;
            flags = NLM_F_CREATE|NLM_F_EXCL;
      } else
            return NOTIFY_DONE;

      if (!nfnetlink_has_listeners(NFNLGRP_CONNTRACK_EXP_NEW))
            return NOTIFY_DONE;

      skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
      if (!skb)
            return NOTIFY_DONE;

      b = skb->tail;

      type |= NFNL_SUBSYS_CTNETLINK_EXP << 8;
      nlh   = NLMSG_PUT(skb, 0, 0, type, sizeof(struct nfgenmsg));
      nfmsg = NLMSG_DATA(nlh);

      nlh->nlmsg_flags    = flags;
      nfmsg->nfgen_family = exp->tuple.src.l3num;
      nfmsg->version        = NFNETLINK_V0;
      nfmsg->res_id         = 0;

      if (ctnetlink_exp_dump_expect(skb, exp) < 0)
            goto nla_put_failure;

      nlh->nlmsg_len = skb->tail - b;
      nfnetlink_send(skb, 0, NFNLGRP_CONNTRACK_EXP_NEW, 0);
      return NOTIFY_DONE;

nlmsg_failure:
nla_put_failure:
      kfree_skb(skb);
      return NOTIFY_DONE;
}
#endif
static int ctnetlink_exp_done(struct netlink_callback *cb)
{
      if (cb->args[1])
            nf_ct_expect_put((struct nf_conntrack_expect *)cb->args[1]);
      return 0;
}

static int
ctnetlink_exp_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
{
      struct nf_conntrack_expect *exp, *last;
      struct nfgenmsg *nfmsg = NLMSG_DATA(cb->nlh);
      struct hlist_node *n;
      u_int8_t l3proto = nfmsg->nfgen_family;

      read_lock_bh(&nf_conntrack_lock);
      last = (struct nf_conntrack_expect *)cb->args[1];
      for (; cb->args[0] < nf_ct_expect_hsize; cb->args[0]++) {
restart:
            hlist_for_each_entry(exp, n, &nf_ct_expect_hash[cb->args[0]],
                             hnode) {
                  if (l3proto && exp->tuple.src.l3num != l3proto)
                        continue;
                  if (cb->args[1]) {
                        if (exp != last)
                              continue;
                        cb->args[1] = 0;
                  }
                  if (ctnetlink_exp_fill_info(skb, NETLINK_CB(cb->skb).pid,
                                        cb->nlh->nlmsg_seq,
                                        IPCTNL_MSG_EXP_NEW,
                                        1, exp) < 0) {
                        atomic_inc(&exp->use);
                        cb->args[1] = (unsigned long)exp;
                        goto out;
                  }
            }
            if (cb->args[1]) {
                  cb->args[1] = 0;
                  goto restart;
            }
      }
out:
      read_unlock_bh(&nf_conntrack_lock);
      if (last)
            nf_ct_expect_put(last);

      return skb->len;
}

static const struct nla_policy exp_nla_policy[CTA_EXPECT_MAX+1] = {
      [CTA_EXPECT_TIMEOUT]    = { .type = NLA_U32 },
      [CTA_EXPECT_ID]         = { .type = NLA_U32 },
};

static int
ctnetlink_get_expect(struct sock *ctnl, struct sk_buff *skb,
                 struct nlmsghdr *nlh, struct nlattr *cda[])
{
      struct nf_conntrack_tuple tuple;
      struct nf_conntrack_expect *exp;
      struct sk_buff *skb2;
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int8_t u3 = nfmsg->nfgen_family;
      int err = 0;

      if (nlh->nlmsg_flags & NLM_F_DUMP) {
            return netlink_dump_start(ctnl, skb, nlh,
                                ctnetlink_exp_dump_table,
                                ctnetlink_exp_done);
      }

      if (cda[CTA_EXPECT_MASTER])
            err = ctnetlink_parse_tuple(cda, &tuple, CTA_EXPECT_MASTER, u3);
      else
            return -EINVAL;

      if (err < 0)
            return err;

      exp = nf_ct_expect_find_get(&tuple);
      if (!exp)
            return -ENOENT;

      if (cda[CTA_EXPECT_ID]) {
            __be32 id = *(__be32 *)nla_data(cda[CTA_EXPECT_ID]);
            if (ntohl(id) != (u32)(unsigned long)exp) {
                  nf_ct_expect_put(exp);
                  return -ENOENT;
            }
      }

      err = -ENOMEM;
      skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
      if (!skb2)
            goto out;

      err = ctnetlink_exp_fill_info(skb2, NETLINK_CB(skb).pid,
                              nlh->nlmsg_seq, IPCTNL_MSG_EXP_NEW,
                              1, exp);
      if (err <= 0)
            goto free;

      nf_ct_expect_put(exp);

      return netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);

free:
      kfree_skb(skb2);
out:
      nf_ct_expect_put(exp);
      return err;
}

static int
ctnetlink_del_expect(struct sock *ctnl, struct sk_buff *skb,
                 struct nlmsghdr *nlh, struct nlattr *cda[])
{
      struct nf_conntrack_expect *exp;
      struct nf_conntrack_tuple tuple;
      struct nf_conntrack_helper *h;
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      struct hlist_node *n, *next;
      u_int8_t u3 = nfmsg->nfgen_family;
      unsigned int i;
      int err;

      if (cda[CTA_EXPECT_TUPLE]) {
            /* delete a single expect by tuple */
            err = ctnetlink_parse_tuple(cda, &tuple, CTA_EXPECT_TUPLE, u3);
            if (err < 0)
                  return err;

            /* bump usage count to 2 */
            exp = nf_ct_expect_find_get(&tuple);
            if (!exp)
                  return -ENOENT;

            if (cda[CTA_EXPECT_ID]) {
                  __be32 id = *(__be32 *)nla_data(cda[CTA_EXPECT_ID]);
                  if (ntohl(id) != (u32)(unsigned long)exp) {
                        nf_ct_expect_put(exp);
                        return -ENOENT;
                  }
            }

            /* after list removal, usage count == 1 */
            nf_ct_unexpect_related(exp);
            /* have to put what we 'get' above.
             * after this line usage count == 0 */
            nf_ct_expect_put(exp);
      } else if (cda[CTA_EXPECT_HELP_NAME]) {
            char *name = nla_data(cda[CTA_EXPECT_HELP_NAME]);
            struct nf_conn_help *m_help;

            /* delete all expectations for this helper */
            write_lock_bh(&nf_conntrack_lock);
            h = __nf_conntrack_helper_find_byname(name);
            if (!h) {
                  write_unlock_bh(&nf_conntrack_lock);
                  return -EINVAL;
            }
            for (i = 0; i < nf_ct_expect_hsize; i++) {
                  hlist_for_each_entry_safe(exp, n, next,
                                      &nf_ct_expect_hash[i],
                                      hnode) {
                        m_help = nfct_help(exp->master);
                        if (m_help->helper == h
                            && del_timer(&exp->timeout)) {
                              nf_ct_unlink_expect(exp);
                              nf_ct_expect_put(exp);
                        }
                  }
            }
            write_unlock_bh(&nf_conntrack_lock);
      } else {
            /* This basically means we have to flush everything*/
            write_lock_bh(&nf_conntrack_lock);
            for (i = 0; i < nf_ct_expect_hsize; i++) {
                  hlist_for_each_entry_safe(exp, n, next,
                                      &nf_ct_expect_hash[i],
                                      hnode) {
                        if (del_timer(&exp->timeout)) {
                              nf_ct_unlink_expect(exp);
                              nf_ct_expect_put(exp);
                        }
                  }
            }
            write_unlock_bh(&nf_conntrack_lock);
      }

      return 0;
}
static int
ctnetlink_change_expect(struct nf_conntrack_expect *x, struct nlattr *cda[])
{
      return -EOPNOTSUPP;
}

static int
ctnetlink_create_expect(struct nlattr *cda[], u_int8_t u3)
{
      struct nf_conntrack_tuple tuple, mask, master_tuple;
      struct nf_conntrack_tuple_hash *h = NULL;
      struct nf_conntrack_expect *exp;
      struct nf_conn *ct;
      struct nf_conn_help *help;
      int err = 0;

      /* caller guarantees that those three CTA_EXPECT_* exist */
      err = ctnetlink_parse_tuple(cda, &tuple, CTA_EXPECT_TUPLE, u3);
      if (err < 0)
            return err;
      err = ctnetlink_parse_tuple(cda, &mask, CTA_EXPECT_MASK, u3);
      if (err < 0)
            return err;
      err = ctnetlink_parse_tuple(cda, &master_tuple, CTA_EXPECT_MASTER, u3);
      if (err < 0)
            return err;

      /* Look for master conntrack of this expectation */
      h = nf_conntrack_find_get(&master_tuple);
      if (!h)
            return -ENOENT;
      ct = nf_ct_tuplehash_to_ctrack(h);
      help = nfct_help(ct);

      if (!help || !help->helper) {
            /* such conntrack hasn't got any helper, abort */
            err = -EINVAL;
            goto out;
      }

      exp = nf_ct_expect_alloc(ct);
      if (!exp) {
            err = -ENOMEM;
            goto out;
      }

      exp->expectfn = NULL;
      exp->flags = 0;
      exp->master = ct;
      exp->helper = NULL;
      memcpy(&exp->tuple, &tuple, sizeof(struct nf_conntrack_tuple));
      memcpy(&exp->mask.src.u3, &mask.src.u3, sizeof(exp->mask.src.u3));
      exp->mask.src.u.all = mask.src.u.all;

      err = nf_ct_expect_related(exp);
      nf_ct_expect_put(exp);

out:
      nf_ct_put(nf_ct_tuplehash_to_ctrack(h));
      return err;
}

static int
ctnetlink_new_expect(struct sock *ctnl, struct sk_buff *skb,
                 struct nlmsghdr *nlh, struct nlattr *cda[])
{
      struct nf_conntrack_tuple tuple;
      struct nf_conntrack_expect *exp;
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int8_t u3 = nfmsg->nfgen_family;
      int err = 0;

      if (!cda[CTA_EXPECT_TUPLE]
          || !cda[CTA_EXPECT_MASK]
          || !cda[CTA_EXPECT_MASTER])
            return -EINVAL;

      err = ctnetlink_parse_tuple(cda, &tuple, CTA_EXPECT_TUPLE, u3);
      if (err < 0)
            return err;

      write_lock_bh(&nf_conntrack_lock);
      exp = __nf_ct_expect_find(&tuple);

      if (!exp) {
            write_unlock_bh(&nf_conntrack_lock);
            err = -ENOENT;
            if (nlh->nlmsg_flags & NLM_F_CREATE)
                  err = ctnetlink_create_expect(cda, u3);
            return err;
      }

      err = -EEXIST;
      if (!(nlh->nlmsg_flags & NLM_F_EXCL))
            err = ctnetlink_change_expect(exp, cda);
      write_unlock_bh(&nf_conntrack_lock);

      return err;
}

#ifdef CONFIG_NF_CONNTRACK_EVENTS
static struct notifier_block ctnl_notifier = {
      .notifier_call    = ctnetlink_conntrack_event,
};

static struct notifier_block ctnl_notifier_exp = {
      .notifier_call    = ctnetlink_expect_event,
};
#endif

static const struct nfnl_callback ctnl_cb[IPCTNL_MSG_MAX] = {
      [IPCTNL_MSG_CT_NEW]           = { .call = ctnetlink_new_conntrack,
                                  .attr_count = CTA_MAX,
                                  .policy = ct_nla_policy },
      [IPCTNL_MSG_CT_GET]           = { .call = ctnetlink_get_conntrack,
                                  .attr_count = CTA_MAX,
                                  .policy = ct_nla_policy },
      [IPCTNL_MSG_CT_DELETE]        = { .call = ctnetlink_del_conntrack,
                                  .attr_count = CTA_MAX,
                                  .policy = ct_nla_policy },
      [IPCTNL_MSG_CT_GET_CTRZERO]   = { .call = ctnetlink_get_conntrack,
                                  .attr_count = CTA_MAX,
                                  .policy = ct_nla_policy },
};

static const struct nfnl_callback ctnl_exp_cb[IPCTNL_MSG_EXP_MAX] = {
      [IPCTNL_MSG_EXP_GET]          = { .call = ctnetlink_get_expect,
                                  .attr_count = CTA_EXPECT_MAX,
                                  .policy = exp_nla_policy },
      [IPCTNL_MSG_EXP_NEW]          = { .call = ctnetlink_new_expect,
                                  .attr_count = CTA_EXPECT_MAX,
                                  .policy = exp_nla_policy },
      [IPCTNL_MSG_EXP_DELETE]       = { .call = ctnetlink_del_expect,
                                  .attr_count = CTA_EXPECT_MAX,
                                  .policy = exp_nla_policy },
};

static const struct nfnetlink_subsystem ctnl_subsys = {
      .name                   = "conntrack",
      .subsys_id              = NFNL_SUBSYS_CTNETLINK,
      .cb_count               = IPCTNL_MSG_MAX,
      .cb                     = ctnl_cb,
};

static const struct nfnetlink_subsystem ctnl_exp_subsys = {
      .name                   = "conntrack_expect",
      .subsys_id              = NFNL_SUBSYS_CTNETLINK_EXP,
      .cb_count               = IPCTNL_MSG_EXP_MAX,
      .cb                     = ctnl_exp_cb,
};

MODULE_ALIAS("ip_conntrack_netlink");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK);
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_EXP);

static int __init ctnetlink_init(void)
{
      int ret;

      printk("ctnetlink v%s: registering with nfnetlink.\n", version);
      ret = nfnetlink_subsys_register(&ctnl_subsys);
      if (ret < 0) {
            printk("ctnetlink_init: cannot register with nfnetlink.\n");
            goto err_out;
      }

      ret = nfnetlink_subsys_register(&ctnl_exp_subsys);
      if (ret < 0) {
            printk("ctnetlink_init: cannot register exp with nfnetlink.\n");
            goto err_unreg_subsys;
      }

#ifdef CONFIG_NF_CONNTRACK_EVENTS
      ret = nf_conntrack_register_notifier(&ctnl_notifier);
      if (ret < 0) {
            printk("ctnetlink_init: cannot register notifier.\n");
            goto err_unreg_exp_subsys;
      }

      ret = nf_ct_expect_register_notifier(&ctnl_notifier_exp);
      if (ret < 0) {
            printk("ctnetlink_init: cannot expect register notifier.\n");
            goto err_unreg_notifier;
      }
#endif

      return 0;

#ifdef CONFIG_NF_CONNTRACK_EVENTS
err_unreg_notifier:
      nf_conntrack_unregister_notifier(&ctnl_notifier);
err_unreg_exp_subsys:
      nfnetlink_subsys_unregister(&ctnl_exp_subsys);
#endif
err_unreg_subsys:
      nfnetlink_subsys_unregister(&ctnl_subsys);
err_out:
      return ret;
}

static void __exit ctnetlink_exit(void)
{
      printk("ctnetlink: unregistering from nfnetlink.\n");

#ifdef CONFIG_NF_CONNTRACK_EVENTS
      nf_ct_expect_unregister_notifier(&ctnl_notifier_exp);
      nf_conntrack_unregister_notifier(&ctnl_notifier);
#endif

      nfnetlink_subsys_unregister(&ctnl_exp_subsys);
      nfnetlink_subsys_unregister(&ctnl_subsys);
      return;
}

module_init(ctnetlink_init);
module_exit(ctnetlink_exit);

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