Logo Search packages:      
Sourcecode: linux-2.6 version File versions

xt_recent.c

/*
 * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
 * Copyright © CC Computer Consultants GmbH, 2007 - 2008
 *
 * 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.
 *
 * This is a replacement of the old ipt_recent module, which carried the
 * following copyright notice:
 *
 * Author: Stephen Frost <sfrost@snowman.net>
 * Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org
 */
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/bitops.h>
#include <linux/skbuff.h>
#include <linux/inet.h>
#include <net/net_namespace.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_recent.h>

MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching for IPv4");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_recent");
MODULE_ALIAS("ip6t_recent");

static unsigned int ip_list_tot = 100;
static unsigned int ip_pkt_list_tot = 20;
static unsigned int ip_list_hash_size = 0;
static unsigned int ip_list_perms = 0644;
static unsigned int ip_list_uid = 0;
static unsigned int ip_list_gid = 0;
module_param(ip_list_tot, uint, 0400);
module_param(ip_pkt_list_tot, uint, 0400);
module_param(ip_list_hash_size, uint, 0400);
module_param(ip_list_perms, uint, 0400);
module_param(ip_list_uid, uint, 0400);
module_param(ip_list_gid, uint, 0400);
MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/xt_recent/* files");
MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/xt_recent/* files");

struct recent_entry {
      struct list_head  list;
      struct list_head  lru_list;
      union nf_inet_addr      addr;
      u_int16_t         family;
      u_int8_t          ttl;
      u_int8_t          index;
      u_int16_t         nstamps;
      unsigned long           stamps[0];
};

struct recent_table {
      struct list_head  list;
      char              name[XT_RECENT_NAME_LEN];
      unsigned int            refcnt;
      unsigned int            entries;
      struct list_head  lru_list;
      struct list_head  iphash[0];
};

static LIST_HEAD(tables);
static DEFINE_SPINLOCK(recent_lock);
static DEFINE_MUTEX(recent_mutex);

#ifdef CONFIG_PROC_FS
#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
static struct proc_dir_entry *proc_old_dir;
#endif
static struct proc_dir_entry *recent_proc_dir;
static const struct file_operations recent_old_fops, recent_mt_fops;
#endif

static u_int32_t hash_rnd;
static bool hash_rnd_initted;

static unsigned int recent_entry_hash4(const union nf_inet_addr *addr)
{
      if (!hash_rnd_initted) {
            get_random_bytes(&hash_rnd, sizeof(hash_rnd));
            hash_rnd_initted = true;
      }
      return jhash_1word((__force u32)addr->ip, hash_rnd) &
             (ip_list_hash_size - 1);
}

static unsigned int recent_entry_hash6(const union nf_inet_addr *addr)
{
      if (!hash_rnd_initted) {
            get_random_bytes(&hash_rnd, sizeof(hash_rnd));
            hash_rnd_initted = true;
      }
      return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), hash_rnd) &
             (ip_list_hash_size - 1);
}

static struct recent_entry *
recent_entry_lookup(const struct recent_table *table,
                const union nf_inet_addr *addrp, u_int16_t family,
                u_int8_t ttl)
{
      struct recent_entry *e;
      unsigned int h;

      if (family == NFPROTO_IPV4)
            h = recent_entry_hash4(addrp);
      else
            h = recent_entry_hash6(addrp);

      list_for_each_entry(e, &table->iphash[h], list)
            if (e->family == family &&
                memcmp(&e->addr, addrp, sizeof(e->addr)) == 0 &&
                (ttl == e->ttl || ttl == 0 || e->ttl == 0))
                  return e;
      return NULL;
}

static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
{
      list_del(&e->list);
      list_del(&e->lru_list);
      kfree(e);
      t->entries--;
}

static struct recent_entry *
recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
              u_int16_t family, u_int8_t ttl)
{
      struct recent_entry *e;

      if (t->entries >= ip_list_tot) {
            e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
            recent_entry_remove(t, e);
      }
      e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
                GFP_ATOMIC);
      if (e == NULL)
            return NULL;
      memcpy(&e->addr, addr, sizeof(e->addr));
      e->ttl       = ttl;
      e->stamps[0] = jiffies;
      e->nstamps   = 1;
      e->index     = 1;
      e->family    = family;
      if (family == NFPROTO_IPV4)
            list_add_tail(&e->list, &t->iphash[recent_entry_hash4(addr)]);
      else
            list_add_tail(&e->list, &t->iphash[recent_entry_hash6(addr)]);
      list_add_tail(&e->lru_list, &t->lru_list);
      t->entries++;
      return e;
}

static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
{
      e->stamps[e->index++] = jiffies;
      if (e->index > e->nstamps)
            e->nstamps = e->index;
      e->index %= ip_pkt_list_tot;
      list_move_tail(&e->lru_list, &t->lru_list);
}

static struct recent_table *recent_table_lookup(const char *name)
{
      struct recent_table *t;

      list_for_each_entry(t, &tables, list)
            if (!strcmp(t->name, name))
                  return t;
      return NULL;
}

static void recent_table_flush(struct recent_table *t)
{
      struct recent_entry *e, *next;
      unsigned int i;

      for (i = 0; i < ip_list_hash_size; i++)
            list_for_each_entry_safe(e, next, &t->iphash[i], list)
                  recent_entry_remove(t, e);
}

static bool
recent_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
      const struct xt_recent_mtinfo *info = par->matchinfo;
      struct recent_table *t;
      struct recent_entry *e;
      union nf_inet_addr addr = {};
      u_int8_t ttl;
      bool ret = info->invert;

      if (par->match->family == NFPROTO_IPV4) {
            const struct iphdr *iph = ip_hdr(skb);

            if (info->side == XT_RECENT_DEST)
                  addr.ip = iph->daddr;
            else
                  addr.ip = iph->saddr;

            ttl = iph->ttl;
      } else {
            const struct ipv6hdr *iph = ipv6_hdr(skb);

            if (info->side == XT_RECENT_DEST)
                  memcpy(&addr.in6, &iph->daddr, sizeof(addr.in6));
            else
                  memcpy(&addr.in6, &iph->saddr, sizeof(addr.in6));

            ttl = iph->hop_limit;
      }

      /* use TTL as seen before forwarding */
      if (par->out != NULL && skb->sk == NULL)
            ttl++;

      spin_lock_bh(&recent_lock);
      t = recent_table_lookup(info->name);
      e = recent_entry_lookup(t, &addr, par->match->family,
                        (info->check_set & XT_RECENT_TTL) ? ttl : 0);
      if (e == NULL) {
            if (!(info->check_set & XT_RECENT_SET))
                  goto out;
            e = recent_entry_init(t, &addr, par->match->family, ttl);
            if (e == NULL)
                  *par->hotdrop = true;
            ret = !ret;
            goto out;
      }

      if (info->check_set & XT_RECENT_SET)
            ret = !ret;
      else if (info->check_set & XT_RECENT_REMOVE) {
            recent_entry_remove(t, e);
            ret = !ret;
      } else if (info->check_set & (XT_RECENT_CHECK | XT_RECENT_UPDATE)) {
            unsigned long time = jiffies - info->seconds * HZ;
            unsigned int i, hits = 0;

            for (i = 0; i < e->nstamps; i++) {
                  if (info->seconds && time_after(time, e->stamps[i]))
                        continue;
                  if (++hits >= info->hit_count) {
                        ret = !ret;
                        break;
                  }
            }
      }

      if (info->check_set & XT_RECENT_SET ||
          (info->check_set & XT_RECENT_UPDATE && ret)) {
            recent_entry_update(t, e);
            e->ttl = ttl;
      }
out:
      spin_unlock_bh(&recent_lock);
      return ret;
}

static bool recent_mt_check(const struct xt_mtchk_param *par)
{
      const struct xt_recent_mtinfo *info = par->matchinfo;
      struct recent_table *t;
#ifdef CONFIG_PROC_FS
      struct proc_dir_entry *pde;
#endif
      unsigned i;
      bool ret = false;

      if (hweight8(info->check_set &
                 (XT_RECENT_SET | XT_RECENT_REMOVE |
                  XT_RECENT_CHECK | XT_RECENT_UPDATE)) != 1)
            return false;
      if ((info->check_set & (XT_RECENT_SET | XT_RECENT_REMOVE)) &&
          (info->seconds || info->hit_count))
            return false;
      if (info->hit_count > ip_pkt_list_tot)
            return false;
      if (info->name[0] == '\0' ||
          strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
            return false;

      mutex_lock(&recent_mutex);
      t = recent_table_lookup(info->name);
      if (t != NULL) {
            t->refcnt++;
            ret = true;
            goto out;
      }

      t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
                GFP_KERNEL);
      if (t == NULL)
            goto out;
      t->refcnt = 1;
      strcpy(t->name, info->name);
      INIT_LIST_HEAD(&t->lru_list);
      for (i = 0; i < ip_list_hash_size; i++)
            INIT_LIST_HEAD(&t->iphash[i]);
#ifdef CONFIG_PROC_FS
      pde = proc_create_data(t->name, ip_list_perms, recent_proc_dir,
              &recent_mt_fops, t);
      if (pde == NULL) {
            kfree(t);
            goto out;
      }
      pde->uid = ip_list_uid;
      pde->gid = ip_list_gid;
#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
      pde = proc_create_data(t->name, ip_list_perms, proc_old_dir,
                  &recent_old_fops, t);
      if (pde == NULL) {
            remove_proc_entry(t->name, proc_old_dir);
            kfree(t);
            goto out;
      }
      pde->uid = ip_list_uid;
      pde->gid = ip_list_gid;
#endif
#endif
      spin_lock_bh(&recent_lock);
      list_add_tail(&t->list, &tables);
      spin_unlock_bh(&recent_lock);
      ret = true;
out:
      mutex_unlock(&recent_mutex);
      return ret;
}

static void recent_mt_destroy(const struct xt_mtdtor_param *par)
{
      const struct xt_recent_mtinfo *info = par->matchinfo;
      struct recent_table *t;

      mutex_lock(&recent_mutex);
      t = recent_table_lookup(info->name);
      if (--t->refcnt == 0) {
            spin_lock_bh(&recent_lock);
            list_del(&t->list);
            spin_unlock_bh(&recent_lock);
#ifdef CONFIG_PROC_FS
#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
            remove_proc_entry(t->name, proc_old_dir);
#endif
            remove_proc_entry(t->name, recent_proc_dir);
#endif
            recent_table_flush(t);
            kfree(t);
      }
      mutex_unlock(&recent_mutex);
}

#ifdef CONFIG_PROC_FS
struct recent_iter_state {
      const struct recent_table *table;
      unsigned int            bucket;
};

static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
      __acquires(recent_lock)
{
      struct recent_iter_state *st = seq->private;
      const struct recent_table *t = st->table;
      struct recent_entry *e;
      loff_t p = *pos;

      spin_lock_bh(&recent_lock);

      for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
            list_for_each_entry(e, &t->iphash[st->bucket], list)
                  if (p-- == 0)
                        return e;
      return NULL;
}

static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
      struct recent_iter_state *st = seq->private;
      const struct recent_table *t = st->table;
      const struct recent_entry *e = v;
      const struct list_head *head = e->list.next;

      while (head == &t->iphash[st->bucket]) {
            if (++st->bucket >= ip_list_hash_size)
                  return NULL;
            head = t->iphash[st->bucket].next;
      }
      (*pos)++;
      return list_entry(head, struct recent_entry, list);
}

static void recent_seq_stop(struct seq_file *s, void *v)
      __releases(recent_lock)
{
      spin_unlock_bh(&recent_lock);
}

static int recent_seq_show(struct seq_file *seq, void *v)
{
      const struct recent_entry *e = v;
      unsigned int i;

      i = (e->index - 1) % ip_pkt_list_tot;
      if (e->family == NFPROTO_IPV4)
            seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
                     &e->addr.ip, e->ttl, e->stamps[i], e->index);
      else
            seq_printf(seq, "src=%pI6 ttl: %u last_seen: %lu oldest_pkt: %u",
                     &e->addr.in6, e->ttl, e->stamps[i], e->index);
      for (i = 0; i < e->nstamps; i++)
            seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
      seq_printf(seq, "\n");
      return 0;
}

static const struct seq_operations recent_seq_ops = {
      .start            = recent_seq_start,
      .next       = recent_seq_next,
      .stop       = recent_seq_stop,
      .show       = recent_seq_show,
};

static int recent_seq_open(struct inode *inode, struct file *file)
{
      struct proc_dir_entry *pde = PDE(inode);
      struct recent_iter_state *st;

      st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
      if (st == NULL)
            return -ENOMEM;

      st->table    = pde->data;
      return 0;
}

#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
static int recent_old_seq_open(struct inode *inode, struct file *filp)
{
      static bool warned_of_old;

      if (unlikely(!warned_of_old)) {
            printk(KERN_INFO KBUILD_MODNAME ": Use of /proc/net/ipt_recent"
                   " is deprecated; use /proc/net/xt_recent.\n");
            warned_of_old = true;
      }
      return recent_seq_open(inode, filp);
}

static ssize_t recent_old_proc_write(struct file *file,
                             const char __user *input,
                             size_t size, loff_t *loff)
{
      const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
      struct recent_table *t = pde->data;
      struct recent_entry *e;
      char buf[sizeof("+255.255.255.255")], *c = buf;
      __be32 addr;
      int add;

      if (size > sizeof(buf))
            size = sizeof(buf);
      if (copy_from_user(buf, input, size))
            return -EFAULT;

      while (isspace(*c))
            c++;

      if (size - (c - buf) < 5)
            return c - buf;
      if (!strncmp(c, "clear", 5)) {
            c += 5;
            spin_lock_bh(&recent_lock);
            recent_table_flush(t);
            spin_unlock_bh(&recent_lock);
            return c - buf;
      }

      switch (*c) {
      case '-':
            add = 0;
            c++;
            break;
      case '+':
            c++;
      default:
            add = 1;
            break;
      }
      addr = in_aton(c);

      spin_lock_bh(&recent_lock);
      e = recent_entry_lookup(t, (const void *)&addr, NFPROTO_IPV4, 0);
      if (e == NULL) {
            if (add)
                  recent_entry_init(t, (const void *)&addr,
                                NFPROTO_IPV4, 0);
      } else {
            if (add)
                  recent_entry_update(t, e);
            else
                  recent_entry_remove(t, e);
      }
      spin_unlock_bh(&recent_lock);
      return size;
}

static const struct file_operations recent_old_fops = {
      .open       = recent_old_seq_open,
      .read       = seq_read,
      .write            = recent_old_proc_write,
      .release    = seq_release_private,
      .owner            = THIS_MODULE,
};
#endif

static ssize_t
recent_mt_proc_write(struct file *file, const char __user *input,
                 size_t size, loff_t *loff)
{
      const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
      struct recent_table *t = pde->data;
      struct recent_entry *e;
      char buf[sizeof("+b335:1d35:1e55:dead:c0de:1715:5afe:c0de")];
      const char *c = buf;
      union nf_inet_addr addr = {};
      u_int16_t family;
      bool add, succ;

      if (size == 0)
            return 0;
      if (size > sizeof(buf))
            size = sizeof(buf);
      if (copy_from_user(buf, input, size) != 0)
            return -EFAULT;

      /* Strict protocol! */
      if (*loff != 0)
            return -ESPIPE;
      switch (*c) {
      case '/': /* flush table */
            spin_lock_bh(&recent_lock);
            recent_table_flush(t);
            spin_unlock_bh(&recent_lock);
            return size;
      case '-': /* remove address */
            add = false;
            break;
      case '+': /* add address */
            add = true;
            break;
      default:
            printk(KERN_INFO KBUILD_MODNAME ": Need +ip, -ip or /\n");
            return -EINVAL;
      }

      ++c;
      --size;
      if (strnchr(c, size, ':') != NULL) {
            family = NFPROTO_IPV6;
            succ   = in6_pton(c, size, (void *)&addr, '\n', NULL);
      } else {
            family = NFPROTO_IPV4;
            succ   = in4_pton(c, size, (void *)&addr, '\n', NULL);
      }

      if (!succ) {
            printk(KERN_INFO KBUILD_MODNAME ": illegal address written "
                   "to procfs\n");
            return -EINVAL;
      }

      spin_lock_bh(&recent_lock);
      e = recent_entry_lookup(t, &addr, family, 0);
      if (e == NULL) {
            if (add)
                  recent_entry_init(t, &addr, family, 0);
      } else {
            if (add)
                  recent_entry_update(t, e);
            else
                  recent_entry_remove(t, e);
      }
      spin_unlock_bh(&recent_lock);
      /* Note we removed one above */
      *loff += size + 1;
      return size + 1;
}

static const struct file_operations recent_mt_fops = {
      .open    = recent_seq_open,
      .read    = seq_read,
      .write   = recent_mt_proc_write,
      .release = seq_release_private,
      .owner   = THIS_MODULE,
};
#endif /* CONFIG_PROC_FS */

static struct xt_match recent_mt_reg[] __read_mostly = {
      {
            .name       = "recent",
            .revision   = 0,
            .family     = NFPROTO_IPV4,
            .match      = recent_mt,
            .matchsize  = sizeof(struct xt_recent_mtinfo),
            .checkentry = recent_mt_check,
            .destroy    = recent_mt_destroy,
            .me         = THIS_MODULE,
      },
      {
            .name       = "recent",
            .revision   = 0,
            .family     = NFPROTO_IPV6,
            .match      = recent_mt,
            .matchsize  = sizeof(struct xt_recent_mtinfo),
            .checkentry = recent_mt_check,
            .destroy    = recent_mt_destroy,
            .me         = THIS_MODULE,
      },
};

static int __init recent_mt_init(void)
{
      int err;

      if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
            return -EINVAL;
      ip_list_hash_size = 1 << fls(ip_list_tot);

      err = xt_register_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
#ifdef CONFIG_PROC_FS
      if (err)
            return err;
      recent_proc_dir = proc_mkdir("xt_recent", init_net.proc_net);
      if (recent_proc_dir == NULL) {
            xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
            err = -ENOMEM;
      }
#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
      if (err < 0)
            return err;
      proc_old_dir = proc_mkdir("ipt_recent", init_net.proc_net);
      if (proc_old_dir == NULL) {
            remove_proc_entry("xt_recent", init_net.proc_net);
            xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
            err = -ENOMEM;
      }
#endif
#endif
      return err;
}

static void __exit recent_mt_exit(void)
{
      BUG_ON(!list_empty(&tables));
      xt_unregister_matches(recent_mt_reg, ARRAY_SIZE(recent_mt_reg));
#ifdef CONFIG_PROC_FS
#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
      remove_proc_entry("ipt_recent", init_net.proc_net);
#endif
      remove_proc_entry("xt_recent", init_net.proc_net);
#endif
}

module_init(recent_mt_init);
module_exit(recent_mt_exit);

Generated by  Doxygen 1.6.0   Back to index