[NETFILTER]: xt_hashlimit match, revision 1

Introduces the xt_hashlimit match revision 1. It adds support for
kernel-level inversion and grouping source and/or destination IP
addresses, allowing to limit on a per-subnet basis. While this would
technically obsolete xt_limit, xt_hashlimit is a more expensive due
to the hashbucketing.

Kernel-level inversion: Previously you had to do user-level inversion:

	iptables -N foo
	iptables -A foo -m hashlimit --hashlimit(-upto) 5/s -j RETURN
	iptables -A foo -j DROP
	iptables -A INPUT -j foo

now it is simpler:

	iptables -A INPUT -m hashlimit --hashlimit-over 5/s -j DROP

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jan Engelhardt 2008-01-31 04:48:13 -08:00 committed by David S. Miller
parent d33b7c06bd
commit 09e410def6
2 changed files with 318 additions and 41 deletions

View file

@ -9,13 +9,16 @@
/* details of this structure hidden by the implementation */
struct xt_hashlimit_htable;
#define XT_HASHLIMIT_HASH_DIP 0x0001
#define XT_HASHLIMIT_HASH_DPT 0x0002
#define XT_HASHLIMIT_HASH_SIP 0x0004
#define XT_HASHLIMIT_HASH_SPT 0x0008
enum {
XT_HASHLIMIT_HASH_DIP = 1 << 0,
XT_HASHLIMIT_HASH_DPT = 1 << 1,
XT_HASHLIMIT_HASH_SIP = 1 << 2,
XT_HASHLIMIT_HASH_SPT = 1 << 3,
XT_HASHLIMIT_INVERT = 1 << 4,
};
struct hashlimit_cfg {
u_int32_t mode; /* bitmask of IPT_HASHLIMIT_HASH_* */
u_int32_t mode; /* bitmask of XT_HASHLIMIT_HASH_* */
u_int32_t avg; /* Average secs between packets * scale */
u_int32_t burst; /* Period multiplier for upper limit. */
@ -37,4 +40,28 @@ struct xt_hashlimit_info {
struct xt_hashlimit_info *master;
} u;
};
struct hashlimit_cfg1 {
u_int32_t mode; /* bitmask of XT_HASHLIMIT_HASH_* */
u_int32_t avg; /* Average secs between packets * scale */
u_int32_t burst; /* Period multiplier for upper limit. */
/* user specified */
u_int32_t size; /* how many buckets */
u_int32_t max; /* max number of entries */
u_int32_t gc_interval; /* gc interval */
u_int32_t expire; /* when do entries expire? */
u_int8_t srcmask, dstmask;
};
struct xt_hashlimit_mtinfo1 {
char name[IFNAMSIZ];
struct hashlimit_cfg1 cfg;
/* Used internally by the kernel */
struct xt_hashlimit_htable *hinfo __attribute__((aligned(8)));
struct xt_hashlimit_mtinfo1 *master __attribute__((aligned(8)));
};
#endif /*_XT_HASHLIMIT_H*/

View file

@ -1,9 +1,9 @@
/* iptables match extension to limit the number of packets per second
* seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
/*
* xt_hashlimit - Netfilter module to limit the number of packets per time
* seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
*
* (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
*
* $Id: ipt_hashlimit.c 3244 2004-10-20 16:24:29Z laforge@netfilter.org $
* (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
* Copyright © CC Computer Consultants GmbH, 2007 - 2008
*
* Development of this code was funded by Astaro AG, http://www.astaro.com/
*/
@ -35,6 +35,7 @@
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
MODULE_ALIAS("ipt_hashlimit");
MODULE_ALIAS("ip6t_hashlimit");
@ -57,7 +58,7 @@ struct dsthash_dst {
__be32 dst[4];
} ip6;
#endif
} addr;
};
__be16 src_port;
__be16 dst_port;
};
@ -81,7 +82,7 @@ struct xt_hashlimit_htable {
atomic_t use;
int family;
struct hashlimit_cfg cfg; /* config */
struct hashlimit_cfg1 cfg; /* config */
/* used internally */
spinlock_t lock; /* lock for list_head */
@ -184,7 +185,7 @@ dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
}
static void htable_gc(unsigned long htlong);
static int htable_create(struct xt_hashlimit_info *minfo, int family)
static int htable_create_v0(struct xt_hashlimit_info *minfo, int family)
{
struct xt_hashlimit_htable *hinfo;
unsigned int size;
@ -210,7 +211,18 @@ static int htable_create(struct xt_hashlimit_info *minfo, int family)
minfo->hinfo = hinfo;
/* copy match config into hashtable config */
memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
hinfo->cfg.mode = minfo->cfg.mode;
hinfo->cfg.avg = minfo->cfg.avg;
hinfo->cfg.burst = minfo->cfg.burst;
hinfo->cfg.max = minfo->cfg.max;
hinfo->cfg.gc_interval = minfo->cfg.gc_interval;
hinfo->cfg.expire = minfo->cfg.expire;
if (family == AF_INET)
hinfo->cfg.srcmask = hinfo->cfg.dstmask = 32;
else
hinfo->cfg.srcmask = hinfo->cfg.dstmask = 128;
hinfo->cfg.size = size;
if (!hinfo->cfg.max)
hinfo->cfg.max = 8 * hinfo->cfg.size;
@ -246,6 +258,70 @@ static int htable_create(struct xt_hashlimit_info *minfo, int family)
return 0;
}
static int htable_create(struct xt_hashlimit_mtinfo1 *minfo,
unsigned int family)
{
struct xt_hashlimit_htable *hinfo;
unsigned int size;
unsigned int i;
if (minfo->cfg.size) {
size = minfo->cfg.size;
} else {
size = (num_physpages << PAGE_SHIFT) / 16384 /
sizeof(struct list_head);
if (num_physpages > 1024 * 1024 * 1024 / PAGE_SIZE)
size = 8192;
if (size < 16)
size = 16;
}
/* FIXME: don't use vmalloc() here or anywhere else -HW */
hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
sizeof(struct list_head) * size);
if (hinfo == NULL) {
printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
return -1;
}
minfo->hinfo = hinfo;
/* copy match config into hashtable config */
memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
hinfo->cfg.size = size;
if (hinfo->cfg.max == 0)
hinfo->cfg.max = 8 * hinfo->cfg.size;
else if (hinfo->cfg.max < hinfo->cfg.size)
hinfo->cfg.max = hinfo->cfg.size;
for (i = 0; i < hinfo->cfg.size; i++)
INIT_HLIST_HEAD(&hinfo->hash[i]);
atomic_set(&hinfo->use, 1);
hinfo->count = 0;
hinfo->family = family;
hinfo->rnd_initialized = 0;
spin_lock_init(&hinfo->lock);
hinfo->pde = create_proc_entry(minfo->name, 0,
family == AF_INET ? hashlimit_procdir4 :
hashlimit_procdir6);
if (hinfo->pde == NULL) {
vfree(hinfo);
return -1;
}
hinfo->pde->proc_fops = &dl_file_ops;
hinfo->pde->data = hinfo;
setup_timer(&hinfo->timer, htable_gc, (unsigned long)hinfo);
hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
add_timer(&hinfo->timer);
spin_lock_bh(&hashlimit_lock);
hlist_add_head(&hinfo->node, &hashlimit_htables);
spin_unlock_bh(&hashlimit_lock);
return 0;
}
static bool select_all(const struct xt_hashlimit_htable *ht,
const struct dsthash_ent *he)
{
@ -388,6 +464,46 @@ static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
dh->rateinfo.prev = now;
}
static inline __be32 maskl(__be32 a, unsigned int l)
{
return htonl(ntohl(a) & ~(~(u_int32_t)0 >> l));
}
static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
{
switch (p) {
case 0:
i[0] = i[1] = 0;
i[2] = i[3] = 0;
break;
case 1 ... 31:
i[0] = maskl(i[0], p);
i[1] = i[2] = i[3] = 0;
break;
case 32:
i[1] = i[2] = i[3] = 0;
break;
case 33 ... 63:
i[1] = maskl(i[1], p - 32);
i[2] = i[3] = 0;
break;
case 64:
i[2] = i[3] = 0;
break;
case 65 ... 95:
i[2] = maskl(i[2], p - 64);
i[3] = 0;
case 96:
i[3] = 0;
break;
case 97 ... 127:
i[3] = maskl(i[3], p - 96);
break;
case 128:
break;
}
}
static int
hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
struct dsthash_dst *dst,
@ -401,9 +517,11 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
switch (hinfo->family) {
case AF_INET:
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
dst->addr.ip.dst = ip_hdr(skb)->daddr;
dst->ip.dst = maskl(ip_hdr(skb)->daddr,
hinfo->cfg.dstmask);
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
dst->addr.ip.src = ip_hdr(skb)->saddr;
dst->ip.src = maskl(ip_hdr(skb)->saddr,
hinfo->cfg.srcmask);
if (!(hinfo->cfg.mode &
(XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
@ -412,12 +530,16 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
break;
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
case AF_INET6:
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
memcpy(&dst->addr.ip6.dst, &ipv6_hdr(skb)->daddr,
sizeof(dst->addr.ip6.dst));
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
memcpy(&dst->addr.ip6.src, &ipv6_hdr(skb)->saddr,
sizeof(dst->addr.ip6.src));
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
sizeof(dst->ip6.dst));
hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
}
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
sizeof(dst->ip6.src));
hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
}
if (!(hinfo->cfg.mode &
(XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
@ -457,10 +579,10 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
}
static bool
hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const struct xt_match *match,
const void *matchinfo, int offset, unsigned int protoff,
bool *hotdrop)
hashlimit_mt_v0(const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const struct xt_match *match,
const void *matchinfo, int offset, unsigned int protoff,
bool *hotdrop)
{
const struct xt_hashlimit_info *r =
((const struct xt_hashlimit_info *)matchinfo)->u.master;
@ -512,9 +634,62 @@ hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
}
static bool
hashlimit_mt_check(const char *tablename, const void *inf,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const struct xt_match *match,
const void *matchinfo, int offset, unsigned int protoff,
bool *hotdrop)
{
const struct xt_hashlimit_mtinfo1 *info = matchinfo;
struct xt_hashlimit_htable *hinfo = info->hinfo;
unsigned long now = jiffies;
struct dsthash_ent *dh;
struct dsthash_dst dst;
if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
goto hotdrop;
spin_lock_bh(&hinfo->lock);
dh = dsthash_find(hinfo, &dst);
if (dh == NULL) {
dh = dsthash_alloc_init(hinfo, &dst);
if (dh == NULL) {
spin_unlock_bh(&hinfo->lock);
goto hotdrop;
}
dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
dh->rateinfo.prev = jiffies;
dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
hinfo->cfg.burst);
dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
hinfo->cfg.burst);
dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
} else {
/* update expiration timeout */
dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
rateinfo_recalc(dh, now);
}
if (dh->rateinfo.credit >= dh->rateinfo.cost) {
/* below the limit */
dh->rateinfo.credit -= dh->rateinfo.cost;
spin_unlock_bh(&hinfo->lock);
return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
}
spin_unlock_bh(&hinfo->lock);
/* default match is underlimit - so over the limit, we need to invert */
return info->cfg.mode & XT_HASHLIMIT_INVERT;
hotdrop:
*hotdrop = true;
return false;
}
static bool
hashlimit_mt_check_v0(const char *tablename, const void *inf,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
struct xt_hashlimit_info *r = matchinfo;
@ -546,7 +721,7 @@ hashlimit_mt_check(const char *tablename, const void *inf,
* create duplicate proc files. -HW */
mutex_lock(&hlimit_mutex);
r->hinfo = htable_find_get(r->name, match->family);
if (!r->hinfo && htable_create(r, match->family) != 0) {
if (!r->hinfo && htable_create_v0(r, match->family) != 0) {
mutex_unlock(&hlimit_mutex);
return false;
}
@ -557,14 +732,68 @@ hashlimit_mt_check(const char *tablename, const void *inf,
return true;
}
static bool
hashlimit_mt_check(const char *tablename, const void *inf,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
struct xt_hashlimit_mtinfo1 *info = matchinfo;
/* Check for overflow. */
if (info->cfg.burst == 0 ||
user2credits(info->cfg.avg * info->cfg.burst) <
user2credits(info->cfg.avg)) {
printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
info->cfg.avg, info->cfg.burst);
return false;
}
if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
return false;
if (info->name[sizeof(info->name)-1] != '\0')
return false;
if (match->family == AF_INET) {
if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
return false;
} else {
if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
return false;
}
/* This is the best we've got: We cannot release and re-grab lock,
* since checkentry() is called before x_tables.c grabs xt_mutex.
* We also cannot grab the hashtable spinlock, since htable_create will
* call vmalloc, and that can sleep. And we cannot just re-search
* the list of htable's in htable_create(), since then we would
* create duplicate proc files. -HW */
mutex_lock(&hlimit_mutex);
info->hinfo = htable_find_get(info->name, match->family);
if (!info->hinfo && htable_create(info, match->family) != 0) {
mutex_unlock(&hlimit_mutex);
return false;
}
mutex_unlock(&hlimit_mutex);
/* Ugly hack: For SMP, we only want to use one set */
info->master = info;
return true;
}
static void
hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
hashlimit_mt_destroy_v0(const struct xt_match *match, void *matchinfo)
{
const struct xt_hashlimit_info *r = matchinfo;
htable_put(r->hinfo);
}
static void
hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
{
const struct xt_hashlimit_mtinfo1 *info = matchinfo;
htable_put(info->hinfo);
}
#ifdef CONFIG_COMPAT
struct compat_xt_hashlimit_info {
char name[IFNAMSIZ];
@ -592,33 +821,54 @@ static int hashlimit_mt_compat_to_user(void __user *dst, void *src)
static struct xt_match hashlimit_mt_reg[] __read_mostly = {
{
.name = "hashlimit",
.revision = 0,
.family = AF_INET,
.match = hashlimit_mt,
.match = hashlimit_mt_v0,
.matchsize = sizeof(struct xt_hashlimit_info),
#ifdef CONFIG_COMPAT
.compatsize = sizeof(struct compat_xt_hashlimit_info),
.compat_from_user = hashlimit_mt_compat_from_user,
.compat_to_user = hashlimit_mt_compat_to_user,
#endif
.checkentry = hashlimit_mt_check,
.destroy = hashlimit_mt_destroy,
.checkentry = hashlimit_mt_check_v0,
.destroy = hashlimit_mt_destroy_v0,
.me = THIS_MODULE
},
{
.name = "hashlimit",
.revision = 1,
.family = AF_INET,
.match = hashlimit_mt,
.matchsize = sizeof(struct xt_hashlimit_mtinfo1),
.checkentry = hashlimit_mt_check,
.destroy = hashlimit_mt_destroy,
.me = THIS_MODULE,
},
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
{
.name = "hashlimit",
.family = AF_INET6,
.match = hashlimit_mt,
.match = hashlimit_mt_v0,
.matchsize = sizeof(struct xt_hashlimit_info),
#ifdef CONFIG_COMPAT
.compatsize = sizeof(struct compat_xt_hashlimit_info),
.compat_from_user = hashlimit_mt_compat_from_user,
.compat_to_user = hashlimit_mt_compat_to_user,
#endif
.checkentry = hashlimit_mt_check,
.destroy = hashlimit_mt_destroy,
.checkentry = hashlimit_mt_check_v0,
.destroy = hashlimit_mt_destroy_v0,
.me = THIS_MODULE
},
{
.name = "hashlimit",
.revision = 1,
.family = AF_INET6,
.match = hashlimit_mt,
.matchsize = sizeof(struct xt_hashlimit_mtinfo1),
.checkentry = hashlimit_mt_check,
.destroy = hashlimit_mt_destroy,
.me = THIS_MODULE,
},
#endif
};
@ -678,9 +928,9 @@ static int dl_seq_real_show(struct dsthash_ent *ent, int family,
return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
"%u.%u.%u.%u:%u %u %u %u\n",
(long)(ent->expires - jiffies)/HZ,
NIPQUAD(ent->dst.addr.ip.src),
NIPQUAD(ent->dst.ip.src),
ntohs(ent->dst.src_port),
NIPQUAD(ent->dst.addr.ip.dst),
NIPQUAD(ent->dst.ip.dst),
ntohs(ent->dst.dst_port),
ent->rateinfo.credit, ent->rateinfo.credit_cap,
ent->rateinfo.cost);
@ -689,9 +939,9 @@ static int dl_seq_real_show(struct dsthash_ent *ent, int family,
return seq_printf(s, "%ld " NIP6_FMT ":%u->"
NIP6_FMT ":%u %u %u %u\n",
(long)(ent->expires - jiffies)/HZ,
NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
NIP6(*(struct in6_addr *)&ent->dst.ip6.src),
ntohs(ent->dst.src_port),
NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
NIP6(*(struct in6_addr *)&ent->dst.ip6.dst),
ntohs(ent->dst.dst_port),
ent->rateinfo.credit, ent->rateinfo.credit_cap,
ent->rateinfo.cost);