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![Pavel Emelyanov](/assets/img/avatar_default.png)
The thing is that recent_mt_destroy first flushes the entries from table with the recent_table_flush and only *after* this removes the proc file, corresponding to that table. Thus, if we manage to write to this file the '+XXX' command we will leak some entries. If we manage to write there a 'clean' command we'll race in two recent_table_flush flows, since the recent_mt_destroy calls this outside the recent_lock. The proper solution as I see it is to remove the proc file first and then go on with flushing the table. This flushing becomes safe w/o the lock, since the table is already inaccessible from the outside. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
501 lines
12 KiB
C
501 lines
12 KiB
C
/*
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* Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This is a replacement of the old ipt_recent module, which carried the
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* following copyright notice:
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*
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* Author: Stephen Frost <sfrost@snowman.net>
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* Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org
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*/
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#include <linux/init.h>
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#include <linux/ip.h>
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#include <linux/moduleparam.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/string.h>
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#include <linux/ctype.h>
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#include <linux/list.h>
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#include <linux/random.h>
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#include <linux/jhash.h>
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#include <linux/bitops.h>
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#include <linux/skbuff.h>
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#include <linux/inet.h>
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#include <net/net_namespace.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ipt_recent.h>
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("Xtables: \"recently-seen\" host matching for IPv4");
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MODULE_LICENSE("GPL");
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static unsigned int ip_list_tot = 100;
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static unsigned int ip_pkt_list_tot = 20;
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static unsigned int ip_list_hash_size = 0;
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static unsigned int ip_list_perms = 0644;
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static unsigned int ip_list_uid = 0;
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static unsigned int ip_list_gid = 0;
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module_param(ip_list_tot, uint, 0400);
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module_param(ip_pkt_list_tot, uint, 0400);
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module_param(ip_list_hash_size, uint, 0400);
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module_param(ip_list_perms, uint, 0400);
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module_param(ip_list_uid, uint, 0400);
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module_param(ip_list_gid, uint, 0400);
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MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
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MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
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MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
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MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/ipt_recent/* files");
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MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/ipt_recent/* files");
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MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/ipt_recent/* files");
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struct recent_entry {
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struct list_head list;
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struct list_head lru_list;
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__be32 addr;
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u_int8_t ttl;
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u_int8_t index;
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u_int16_t nstamps;
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unsigned long stamps[0];
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};
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struct recent_table {
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struct list_head list;
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char name[IPT_RECENT_NAME_LEN];
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#ifdef CONFIG_PROC_FS
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struct proc_dir_entry *proc;
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#endif
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unsigned int refcnt;
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unsigned int entries;
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struct list_head lru_list;
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struct list_head iphash[0];
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};
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static LIST_HEAD(tables);
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static DEFINE_SPINLOCK(recent_lock);
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static DEFINE_MUTEX(recent_mutex);
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#ifdef CONFIG_PROC_FS
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static struct proc_dir_entry *proc_dir;
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static const struct file_operations recent_fops;
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#endif
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static u_int32_t hash_rnd;
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static int hash_rnd_initted;
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static unsigned int recent_entry_hash(__be32 addr)
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{
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if (!hash_rnd_initted) {
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get_random_bytes(&hash_rnd, 4);
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hash_rnd_initted = 1;
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}
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return jhash_1word((__force u32)addr, hash_rnd) & (ip_list_hash_size - 1);
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}
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static struct recent_entry *
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recent_entry_lookup(const struct recent_table *table, __be32 addr, u_int8_t ttl)
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{
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struct recent_entry *e;
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unsigned int h;
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h = recent_entry_hash(addr);
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list_for_each_entry(e, &table->iphash[h], list)
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if (e->addr == addr && (ttl == e->ttl || !ttl || !e->ttl))
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return e;
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return NULL;
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}
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static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
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{
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list_del(&e->list);
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list_del(&e->lru_list);
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kfree(e);
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t->entries--;
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}
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static struct recent_entry *
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recent_entry_init(struct recent_table *t, __be32 addr, u_int8_t ttl)
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{
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struct recent_entry *e;
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if (t->entries >= ip_list_tot) {
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e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
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recent_entry_remove(t, e);
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}
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e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
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GFP_ATOMIC);
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if (e == NULL)
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return NULL;
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e->addr = addr;
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e->ttl = ttl;
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e->stamps[0] = jiffies;
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e->nstamps = 1;
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e->index = 1;
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list_add_tail(&e->list, &t->iphash[recent_entry_hash(addr)]);
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list_add_tail(&e->lru_list, &t->lru_list);
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t->entries++;
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return e;
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}
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static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
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{
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e->stamps[e->index++] = jiffies;
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if (e->index > e->nstamps)
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e->nstamps = e->index;
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e->index %= ip_pkt_list_tot;
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list_move_tail(&e->lru_list, &t->lru_list);
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}
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static struct recent_table *recent_table_lookup(const char *name)
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{
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struct recent_table *t;
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list_for_each_entry(t, &tables, list)
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if (!strcmp(t->name, name))
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return t;
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return NULL;
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}
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static void recent_table_flush(struct recent_table *t)
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{
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struct recent_entry *e, *next;
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unsigned int i;
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for (i = 0; i < ip_list_hash_size; i++)
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list_for_each_entry_safe(e, next, &t->iphash[i], list)
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recent_entry_remove(t, e);
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}
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static bool
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recent_mt(const struct sk_buff *skb, const struct net_device *in,
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const struct net_device *out, const struct xt_match *match,
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const void *matchinfo, int offset, unsigned int protoff,
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bool *hotdrop)
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{
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const struct ipt_recent_info *info = matchinfo;
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struct recent_table *t;
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struct recent_entry *e;
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__be32 addr;
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u_int8_t ttl;
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bool ret = info->invert;
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if (info->side == IPT_RECENT_DEST)
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addr = ip_hdr(skb)->daddr;
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else
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addr = ip_hdr(skb)->saddr;
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ttl = ip_hdr(skb)->ttl;
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/* use TTL as seen before forwarding */
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if (out && !skb->sk)
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ttl++;
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spin_lock_bh(&recent_lock);
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t = recent_table_lookup(info->name);
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e = recent_entry_lookup(t, addr,
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info->check_set & IPT_RECENT_TTL ? ttl : 0);
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if (e == NULL) {
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if (!(info->check_set & IPT_RECENT_SET))
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goto out;
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e = recent_entry_init(t, addr, ttl);
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if (e == NULL)
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*hotdrop = true;
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ret = !ret;
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goto out;
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}
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if (info->check_set & IPT_RECENT_SET)
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ret = !ret;
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else if (info->check_set & IPT_RECENT_REMOVE) {
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recent_entry_remove(t, e);
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ret = !ret;
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} else if (info->check_set & (IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) {
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unsigned long time = jiffies - info->seconds * HZ;
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unsigned int i, hits = 0;
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for (i = 0; i < e->nstamps; i++) {
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if (info->seconds && time_after(time, e->stamps[i]))
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continue;
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if (++hits >= info->hit_count) {
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ret = !ret;
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break;
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}
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}
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}
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if (info->check_set & IPT_RECENT_SET ||
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(info->check_set & IPT_RECENT_UPDATE && ret)) {
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recent_entry_update(t, e);
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e->ttl = ttl;
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}
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out:
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spin_unlock_bh(&recent_lock);
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return ret;
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}
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static bool
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recent_mt_check(const char *tablename, const void *ip,
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const struct xt_match *match, void *matchinfo,
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unsigned int hook_mask)
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{
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const struct ipt_recent_info *info = matchinfo;
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struct recent_table *t;
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unsigned i;
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bool ret = false;
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if (hweight8(info->check_set &
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(IPT_RECENT_SET | IPT_RECENT_REMOVE |
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IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) != 1)
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return false;
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if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
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(info->seconds || info->hit_count))
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return false;
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if (info->hit_count > ip_pkt_list_tot)
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return false;
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if (info->name[0] == '\0' ||
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strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
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return false;
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mutex_lock(&recent_mutex);
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t = recent_table_lookup(info->name);
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if (t != NULL) {
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t->refcnt++;
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ret = true;
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goto out;
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}
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t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
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GFP_KERNEL);
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if (t == NULL)
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goto out;
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t->refcnt = 1;
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strcpy(t->name, info->name);
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INIT_LIST_HEAD(&t->lru_list);
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for (i = 0; i < ip_list_hash_size; i++)
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INIT_LIST_HEAD(&t->iphash[i]);
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#ifdef CONFIG_PROC_FS
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t->proc = proc_create(t->name, ip_list_perms, proc_dir, &recent_fops);
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if (t->proc == NULL) {
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kfree(t);
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goto out;
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}
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t->proc->uid = ip_list_uid;
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t->proc->gid = ip_list_gid;
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t->proc->data = t;
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#endif
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spin_lock_bh(&recent_lock);
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list_add_tail(&t->list, &tables);
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spin_unlock_bh(&recent_lock);
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ret = true;
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out:
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mutex_unlock(&recent_mutex);
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return ret;
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}
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static void recent_mt_destroy(const struct xt_match *match, void *matchinfo)
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{
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const struct ipt_recent_info *info = matchinfo;
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struct recent_table *t;
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mutex_lock(&recent_mutex);
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t = recent_table_lookup(info->name);
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if (--t->refcnt == 0) {
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spin_lock_bh(&recent_lock);
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list_del(&t->list);
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spin_unlock_bh(&recent_lock);
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#ifdef CONFIG_PROC_FS
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remove_proc_entry(t->name, proc_dir);
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#endif
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recent_table_flush(t);
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kfree(t);
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}
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mutex_unlock(&recent_mutex);
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}
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#ifdef CONFIG_PROC_FS
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struct recent_iter_state {
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struct recent_table *table;
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unsigned int bucket;
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};
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static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
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__acquires(recent_lock)
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{
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struct recent_iter_state *st = seq->private;
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const struct recent_table *t = st->table;
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struct recent_entry *e;
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loff_t p = *pos;
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spin_lock_bh(&recent_lock);
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for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
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list_for_each_entry(e, &t->iphash[st->bucket], list)
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if (p-- == 0)
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return e;
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return NULL;
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}
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static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct recent_iter_state *st = seq->private;
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const struct recent_table *t = st->table;
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struct recent_entry *e = v;
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struct list_head *head = e->list.next;
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while (head == &t->iphash[st->bucket]) {
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if (++st->bucket >= ip_list_hash_size)
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return NULL;
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head = t->iphash[st->bucket].next;
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}
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(*pos)++;
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return list_entry(head, struct recent_entry, list);
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}
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static void recent_seq_stop(struct seq_file *s, void *v)
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__releases(recent_lock)
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{
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spin_unlock_bh(&recent_lock);
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}
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static int recent_seq_show(struct seq_file *seq, void *v)
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{
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const struct recent_entry *e = v;
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unsigned int i;
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i = (e->index - 1) % ip_pkt_list_tot;
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seq_printf(seq, "src=%u.%u.%u.%u ttl: %u last_seen: %lu oldest_pkt: %u",
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NIPQUAD(e->addr), e->ttl, e->stamps[i], e->index);
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for (i = 0; i < e->nstamps; i++)
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seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
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seq_printf(seq, "\n");
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return 0;
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}
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static const struct seq_operations recent_seq_ops = {
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.start = recent_seq_start,
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.next = recent_seq_next,
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.stop = recent_seq_stop,
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.show = recent_seq_show,
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};
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static int recent_seq_open(struct inode *inode, struct file *file)
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{
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struct proc_dir_entry *pde = PDE(inode);
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struct recent_iter_state *st;
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st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
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if (st == NULL)
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return -ENOMEM;
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st->table = pde->data;
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return 0;
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}
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static ssize_t recent_proc_write(struct file *file, const char __user *input,
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size_t size, loff_t *loff)
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{
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const struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
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struct recent_table *t = pde->data;
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struct recent_entry *e;
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char buf[sizeof("+255.255.255.255")], *c = buf;
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__be32 addr;
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int add;
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if (size > sizeof(buf))
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size = sizeof(buf);
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if (copy_from_user(buf, input, size))
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return -EFAULT;
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while (isspace(*c))
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c++;
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if (size - (c - buf) < 5)
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return c - buf;
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if (!strncmp(c, "clear", 5)) {
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c += 5;
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spin_lock_bh(&recent_lock);
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recent_table_flush(t);
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spin_unlock_bh(&recent_lock);
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return c - buf;
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}
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switch (*c) {
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case '-':
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add = 0;
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c++;
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break;
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case '+':
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c++;
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default:
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add = 1;
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break;
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}
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addr = in_aton(c);
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spin_lock_bh(&recent_lock);
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e = recent_entry_lookup(t, addr, 0);
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if (e == NULL) {
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if (add)
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recent_entry_init(t, addr, 0);
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} else {
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if (add)
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recent_entry_update(t, e);
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else
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recent_entry_remove(t, e);
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}
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spin_unlock_bh(&recent_lock);
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return size;
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}
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static const struct file_operations recent_fops = {
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.open = recent_seq_open,
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.read = seq_read,
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.write = recent_proc_write,
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.release = seq_release_private,
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.owner = THIS_MODULE,
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};
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#endif /* CONFIG_PROC_FS */
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static struct xt_match recent_mt_reg __read_mostly = {
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.name = "recent",
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.family = AF_INET,
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.match = recent_mt,
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.matchsize = sizeof(struct ipt_recent_info),
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.checkentry = recent_mt_check,
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.destroy = recent_mt_destroy,
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.me = THIS_MODULE,
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};
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static int __init recent_mt_init(void)
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{
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int err;
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if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
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return -EINVAL;
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ip_list_hash_size = 1 << fls(ip_list_tot);
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err = xt_register_match(&recent_mt_reg);
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#ifdef CONFIG_PROC_FS
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if (err)
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return err;
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proc_dir = proc_mkdir("ipt_recent", init_net.proc_net);
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if (proc_dir == NULL) {
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xt_unregister_match(&recent_mt_reg);
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err = -ENOMEM;
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}
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#endif
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return err;
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}
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static void __exit recent_mt_exit(void)
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{
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BUG_ON(!list_empty(&tables));
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xt_unregister_match(&recent_mt_reg);
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#ifdef CONFIG_PROC_FS
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remove_proc_entry("ipt_recent", init_net.proc_net);
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#endif
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}
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module_init(recent_mt_init);
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module_exit(recent_mt_exit);
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