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@xxxxxxxxx>
---
diff --git a/include/linux/netfilter/xt_string.h b/include/linux/netfilter/xt_string.h
index bb21dd1..8a6ba7b 100644
--- a/include/linux/netfilter/xt_string.h
+++ b/include/linux/netfilter/xt_string.h
@@ -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;
diff --git a/net/netfilter/xt_string.c b/net/netfilter/xt_string.c
index 72f694d..4903182 100644
--- a/net/netfilter/xt_string.c
+++ b/net/netfilter/xt_string.c
@@ -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 +84,17 @@ 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,
+ .destroy = string_mt_destroy,
+ .matchsize = sizeof(struct xt_string_info),
+ .me = THIS_MODULE
+ },
+ {
+ .name = "string",
+ .revision = 1,
.family = AF_INET,
.checkentry = string_mt_check,
.match = string_mt,
@@ -81,6 +104,17 @@ static struct xt_match string_mt_reg[] __read_mostly = {
},
{
.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,
---
--
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