ClabureDB: Classified Bug-Reports Database

  /*
   * 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];
 #ifdef CONFIG_PROC_FS
         struct proc_dir_entry        *proc_old, *proc;
 #endif
         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;
        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
        t->proc = proc_create_data(t->name, ip_list_perms, recent_proc_dir,
                  &recent_mt_fops, t);
        if (t->proc == NULL) {
                kfree(t);
                goto out;
        }
#ifdef CONFIG_NETFILTER_XT_MATCH_RECENT_PROC_COMPAT
        t->proc_old = proc_create_data(t->name, ip_list_perms, proc_old_dir,
                      &recent_old_fops, t);
        if (t->proc_old == NULL) {
                remove_proc_entry(t->name, proc_old_dir);
                kfree(t);
                goto out;
        }
        t->proc_old->uid   = ip_list_uid;
        t->proc_old->gid   = ip_list_gid;
#endif
        t->proc->uid       = ip_list_uid;
        t->proc->gid       = ip_list_gid;
#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=" NIPQUAD_FMT " ttl: %u last_seen: %lu "
                           "oldest_pkt: %u", NIPQUAD(e->addr.ip), e->ttl,
                           e->stamps[i], e->index);
        else
                seq_printf(seq, "src=" NIP6_FMT " ttl: %u last_seen: %lu "
                           "oldest_pkt: %u", NIP6(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);