mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-15 16:24:13 +08:00
[NETFILTER]: Add u32 match
Along comes... xt_u32, a revamped ipt_u32 from POM-NG, Plus: * 2007-06-02: added ipv6 support * 2007-06-05: uses kmalloc for the big buffer * 2007-06-05: added inversion * 2007-06-20: use skb_copy_bits() and get rid of the big buffer and lock (suggested by Pablo Neira Ayuso) Signed-off-by: Jan Engelhardt <jengelh@gmx.de> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
f4a607bfae
commit
1b50b8a371
40
include/linux/netfilter/xt_u32.h
Normal file
40
include/linux/netfilter/xt_u32.h
Normal file
@ -0,0 +1,40 @@
|
||||
#ifndef _XT_U32_H
|
||||
#define _XT_U32_H 1
|
||||
|
||||
enum xt_u32_ops {
|
||||
XT_U32_AND,
|
||||
XT_U32_LEFTSH,
|
||||
XT_U32_RIGHTSH,
|
||||
XT_U32_AT,
|
||||
};
|
||||
|
||||
struct xt_u32_location_element {
|
||||
u_int32_t number;
|
||||
u_int8_t nextop;
|
||||
};
|
||||
|
||||
struct xt_u32_value_element {
|
||||
u_int32_t min;
|
||||
u_int32_t max;
|
||||
};
|
||||
|
||||
/*
|
||||
* Any way to allow for an arbitrary number of elements?
|
||||
* For now, I settle with a limit of 10 each.
|
||||
*/
|
||||
#define XT_U32_MAXSIZE 10
|
||||
|
||||
struct xt_u32_test {
|
||||
struct xt_u32_location_element location[XT_U32_MAXSIZE+1];
|
||||
struct xt_u32_value_element value[XT_U32_MAXSIZE+1];
|
||||
u_int8_t nnums;
|
||||
u_int8_t nvalues;
|
||||
};
|
||||
|
||||
struct xt_u32 {
|
||||
struct xt_u32_test tests[XT_U32_MAXSIZE+1];
|
||||
u_int8_t ntests;
|
||||
u_int8_t invert;
|
||||
};
|
||||
|
||||
#endif /* _XT_U32_H */
|
@ -635,6 +635,19 @@ config NETFILTER_XT_MATCH_TCPMSS
|
||||
|
||||
To compile it as a module, choose M here. If unsure, say N.
|
||||
|
||||
config NETFILTER_XT_MATCH_U32
|
||||
tristate '"u32" match support'
|
||||
depends on NETFILTER_XTABLES
|
||||
---help---
|
||||
u32 allows you to extract quantities of up to 4 bytes from a packet,
|
||||
AND them with specified masks, shift them by specified amounts and
|
||||
test whether the results are in any of a set of specified ranges.
|
||||
The specification of what to extract is general enough to skip over
|
||||
headers with lengths stored in the packet, as in IP or TCP header
|
||||
lengths.
|
||||
|
||||
Details and examples are in the kernel module source.
|
||||
|
||||
config NETFILTER_XT_MATCH_HASHLIMIT
|
||||
tristate '"hashlimit" match support'
|
||||
depends on NETFILTER_XTABLES && (IP6_NF_IPTABLES || IP6_NF_IPTABLES=n)
|
||||
|
@ -72,4 +72,5 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_STATISTIC) += xt_statistic.o
|
||||
obj-$(CONFIG_NETFILTER_XT_MATCH_STRING) += xt_string.o
|
||||
obj-$(CONFIG_NETFILTER_XT_MATCH_TCPMSS) += xt_tcpmss.o
|
||||
obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
|
||||
obj-$(CONFIG_NETFILTER_XT_MATCH_U32) += xt_u32.o
|
||||
obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o
|
||||
|
135
net/netfilter/xt_u32.c
Normal file
135
net/netfilter/xt_u32.c
Normal file
@ -0,0 +1,135 @@
|
||||
/*
|
||||
* xt_u32 - kernel module to match u32 packet content
|
||||
*
|
||||
* Original author: Don Cohen <don@isis.cs3-inc.com>
|
||||
* © Jan Engelhardt <jengelh@gmx.de>, 2007
|
||||
*/
|
||||
|
||||
#include <linux/module.h>
|
||||
#include <linux/moduleparam.h>
|
||||
#include <linux/spinlock.h>
|
||||
#include <linux/skbuff.h>
|
||||
#include <linux/types.h>
|
||||
#include <linux/netfilter/x_tables.h>
|
||||
#include <linux/netfilter/xt_u32.h>
|
||||
|
||||
static bool u32_match_it(const struct xt_u32 *data,
|
||||
const struct sk_buff *skb)
|
||||
{
|
||||
const struct xt_u32_test *ct;
|
||||
unsigned int testind;
|
||||
unsigned int nnums;
|
||||
unsigned int nvals;
|
||||
unsigned int i;
|
||||
u_int32_t pos;
|
||||
u_int32_t val;
|
||||
u_int32_t at;
|
||||
int ret;
|
||||
|
||||
/*
|
||||
* Small example: "0 >> 28 == 4 && 8 & 0xFF0000 >> 16 = 6, 17"
|
||||
* (=IPv4 and (TCP or UDP)). Outer loop runs over the "&&" operands.
|
||||
*/
|
||||
for (testind = 0; testind < data->ntests; ++testind) {
|
||||
ct = &data->tests[testind];
|
||||
at = 0;
|
||||
pos = ct->location[0].number;
|
||||
|
||||
if (skb->len < 4 || pos > skb->len - 4);
|
||||
return false;
|
||||
|
||||
ret = skb_copy_bits(skb, pos, &val, sizeof(val));
|
||||
BUG_ON(ret < 0);
|
||||
val = ntohl(val);
|
||||
nnums = ct->nnums;
|
||||
|
||||
/* Inner loop runs over "&", "<<", ">>" and "@" operands */
|
||||
for (i = 1; i < nnums; ++i) {
|
||||
u_int32_t number = ct->location[i].number;
|
||||
switch (ct->location[i].nextop) {
|
||||
case XT_U32_AND:
|
||||
val &= number;
|
||||
break;
|
||||
case XT_U32_LEFTSH:
|
||||
val <<= number;
|
||||
break;
|
||||
case XT_U32_RIGHTSH:
|
||||
val >>= number;
|
||||
break;
|
||||
case XT_U32_AT:
|
||||
if (at + val < at)
|
||||
return false;
|
||||
at += val;
|
||||
pos = number;
|
||||
if (at + 4 < at || skb->len < at + 4 ||
|
||||
pos > skb->len - at - 4)
|
||||
return false;
|
||||
|
||||
ret = skb_copy_bits(skb, at + pos, &val,
|
||||
sizeof(val));
|
||||
BUG_ON(ret < 0);
|
||||
val = ntohl(val);
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
/* Run over the "," and ":" operands */
|
||||
nvals = ct->nvalues;
|
||||
for (i = 0; i < nvals; ++i)
|
||||
if (ct->value[i].min <= val && val <= ct->value[i].max)
|
||||
break;
|
||||
|
||||
if (i >= ct->nvalues)
|
||||
return false;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
static bool u32_match(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_u32 *data = matchinfo;
|
||||
bool ret;
|
||||
|
||||
ret = u32_match_it(data, skb);
|
||||
return ret ^ data->invert;
|
||||
}
|
||||
|
||||
static struct xt_match u32_reg[] = {
|
||||
{
|
||||
.name = "u32",
|
||||
.family = AF_INET,
|
||||
.match = u32_match,
|
||||
.matchsize = sizeof(struct xt_u32),
|
||||
.me = THIS_MODULE,
|
||||
},
|
||||
{
|
||||
.name = "u32",
|
||||
.family = AF_INET6,
|
||||
.match = u32_match,
|
||||
.matchsize = sizeof(struct xt_u32),
|
||||
.me = THIS_MODULE,
|
||||
},
|
||||
};
|
||||
|
||||
static int __init xt_u32_init(void)
|
||||
{
|
||||
return xt_register_matches(u32_reg, ARRAY_SIZE(u32_reg));
|
||||
}
|
||||
|
||||
static void __exit xt_u32_exit(void)
|
||||
{
|
||||
xt_unregister_matches(u32_reg, ARRAY_SIZE(u32_reg));
|
||||
}
|
||||
|
||||
module_init(xt_u32_init);
|
||||
module_exit(xt_u32_exit);
|
||||
MODULE_AUTHOR("Jan Engelhardt <jengelh@gmx.de>");
|
||||
MODULE_DESCRIPTION("netfilter u32 match module");
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_ALIAS("ipt_u32");
|
||||
MODULE_ALIAS("ip6t_u32");
|
Loading…
Reference in New Issue
Block a user