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netfilter: fix string extension for case insensitive pattern matching 

The flag XT_STRING_FLAG_IGNORECASE indicates case insensitive string
matching. netfilter can find cmd.exe, Cmd.exe, cMd.exe and etc easily.

A new revision 1 was added, in the meantime invert of xt_string_info
was moved into flags as a flag. If revision is 1, The flag
XT_STRING_FLAG_INVERT indicates invert matching.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Joonwoo Park 2008-07-08 02:38:56 -07:00 committed by David S. Miller
parent dde77e6044
commit 4ad3f26162
2 changed files with 50 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/linux/netfilter/xt_string.h
View File

@ -4,6 +4,11 @@
#define XT_STRING_MAX_PATTERN_SIZE 128
#define XT_STRING_MAX_ALGO_NAME_SIZE 16
enum {
XT_STRING_FLAG_INVERT = 0x01,
XT_STRING_FLAG_IGNORECASE = 0x02
};
struct xt_string_info
{
u_int16_t from_offset;
@ -11,7 +16,15 @@ struct xt_string_info
char algo[XT_STRING_MAX_ALGO_NAME_SIZE];
char pattern[XT_STRING_MAX_PATTERN_SIZE];
u_int8_t patlen;
u_int8_t invert;
union {
struct {
u_int8_t invert;
} v0;
struct {
u_int8_t flags;
} v1;
} u;
/* Used internally by the kernel */
struct ts_config __attribute__((aligned(8))) *config;

38
net/netfilter/xt_string.c
View File

@ -29,12 +29,16 @@ string_mt(const struct sk_buff *skb, const struct net_device *in,
{
const struct xt_string_info *conf = matchinfo;
struct ts_state state;
int invert;
memset(&state, 0, sizeof(struct ts_state));
invert = (match->revision == 0 ? conf->u.v0.invert :
conf->u.v1.flags & XT_STRING_FLAG_INVERT);
return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
conf->to_offset, conf->config, &state)
!= UINT_MAX) ^ conf->invert;
!= UINT_MAX) ^ invert;
}
#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
@ -46,6 +50,7 @@ string_mt_check(const char *tablename, const void *ip,
{
struct xt_string_info *conf = matchinfo;
struct ts_config *ts_conf;
int flags = TS_AUTOLOAD;
/* Damn, can't handle this case properly with iptables... */
if (conf->from_offset > conf->to_offset)
@ -54,8 +59,15 @@ string_mt_check(const char *tablename, const void *ip,
return false;
if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
return false;
if (match->revision == 1) {
if (conf->u.v1.flags &
~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
return false;
if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
flags |= TS_IGNORECASE;
}
ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
GFP_KERNEL, TS_AUTOLOAD);
GFP_KERNEL, flags);
if (IS_ERR(ts_conf))
return false;
@ -72,6 +84,7 @@ static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
static struct xt_match string_mt_reg[] __read_mostly = {
{
.name = "string",
.revision = 0,
.family = AF_INET,
.checkentry = string_mt_check,
.match = string_mt,
@ -81,6 +94,27 @@ static struct xt_match string_mt_reg[] __read_mostly = {
},
{
.name = "string",
.revision = 1,
.family = AF_INET,
.checkentry = string_mt_check,
.match = string_mt,
.destroy = string_mt_destroy,
.matchsize = sizeof(struct xt_string_info),
.me = THIS_MODULE
},
{
.name = "string",
.revision = 0,
.family = AF_INET6,
.checkentry = string_mt_check,
.match = string_mt,
.destroy = string_mt_destroy,
.matchsize = sizeof(struct xt_string_info),
.me = THIS_MODULE
},
{
.name = "string",
.revision = 1,
.family = AF_INET6,
.checkentry = string_mt_check,
.match = string_mt,