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transforms: move urldecode to rust

Browse Source 
Ticket: 7229
pull/12094/head
Philippe Antoine 1 year ago committed by Victor Julien
parent 8984bc6801
commit 63324b7368
6 changed files with 144 additions and 213 deletions
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1
rust/src/detect/transforms/mod.rs
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@ -25,6 +25,7 @@ pub mod dotprefix;
pub mod hash;
pub mod http_headers;
pub mod strip_whitespace;
pub mod urldecode;
pub mod xor;
#[repr(C)]

143
rust/src/detect/transforms/urldecode.rs
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@ -0,0 +1,143 @@
/* Copyright (C) 2024 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
use super::{
DetectHelperTransformRegister, DetectSignatureAddTransform, InspectionBufferCheckAndExpand,
InspectionBufferLength, InspectionBufferPtr, InspectionBufferTruncate, SCTransformTableElmt,
};
use crate::detect::SIGMATCH_NOOPT;
use std::os::raw::{c_int, c_void};
use std::ptr;
static mut G_TRANSFORM_URL_DECODE_ID: c_int = 0;
#[no_mangle]
unsafe extern "C" fn url_decode_setup(
_de: *mut c_void, s: *mut c_void, _opt: *const std::os::raw::c_char,
) -> c_int {
return DetectSignatureAddTransform(s, G_TRANSFORM_URL_DECODE_ID, ptr::null_mut());
}
fn hex_value(i: u8) -> Option<u8> {
match i {
0x30..=0x39 => Some(i - 0x30),
0x41..=0x46 => Some(i - 0x41 + 10),
0x61..=0x66 => Some(i - 0x61 + 10),
_ => None,
}
}
fn url_decode_transform_do(input: &[u8], output: &mut [u8]) -> u32 {
let mut state = (0u8, 0u8);
let mut nb = 0;
for &i in input.iter() {
if state.0 > 0 {
if let Some(v) = hex_value(i) {
if state.0 == 1 {
state = (2, i);
} else {
output[nb] = v | (hex_value(state.1).unwrap() << 4);
nb += 1;
state = (0u8, 0u8);
}
} else {
output[nb] = b'%';
nb += 1;
if state.0 > 1 {
output[nb] = state.1;
nb += 1;
}
output[nb] = i;
nb += 1;
state = (0u8, 0u8);
}
} else if i == b'%' {
state = (1u8, 0u8);
} else {
if i == b'+' {
output[nb] = b' ';
} else {
output[nb] = i;
}
nb += 1;
}
}
if state.0 > 0 {
output[nb] = b'%';
nb += 1;
if state.0 == 2 {
output[nb] = state.1;
nb += 1;
}
}
return nb as u32;
}
#[no_mangle]
unsafe extern "C" fn url_decode_transform(buffer: *mut c_void, _ctx: *mut c_void) {
let input = InspectionBufferPtr(buffer);
let input_len = InspectionBufferLength(buffer);
if input.is_null() || input_len == 0 {
return;
}
let input = build_slice!(input, input_len as usize);
let output = InspectionBufferCheckAndExpand(buffer, input_len);
if output.is_null() {
// allocation failure
return;
}
let output = std::slice::from_raw_parts_mut(output, input_len as usize);
let out_len = url_decode_transform_do(input, output);
InspectionBufferTruncate(buffer, out_len);
}
#[no_mangle]
pub unsafe extern "C" fn DetectTransformUrlDecodeRegister() {
let kw = SCTransformTableElmt {
name: b"url_decode\0".as_ptr() as *const libc::c_char,
desc: b"modify buffer to decode urlencoded data before inspection\0".as_ptr()
as *const libc::c_char,
url: b"/rules/transforms.html#url-decode\0".as_ptr() as *const libc::c_char,
Setup: url_decode_setup,
flags: SIGMATCH_NOOPT,
Transform: url_decode_transform,
Free: None,
TransformValidate: None,
};
unsafe {
G_TRANSFORM_URL_DECODE_ID = DetectHelperTransformRegister(&kw);
if G_TRANSFORM_URL_DECODE_ID < 0 {
SCLogWarning!("Failed registering transform dot_prefix");
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_url_decode_transform() {
let buf = b"Suricata%20is+%27%61wesome%21%27%25%30%30%ZZ%4";
let mut out = vec![0; buf.len()];
let nb = url_decode_transform_do(buf, &mut out);
assert_eq!(&out[..nb as usize], b"Suricata is 'awesome!'%00%ZZ%4");
}
}

2
src/Makefile.am
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@ -307,7 +307,6 @@ noinst_HEADERS = \
detect-tos.h \
detect-transform-base64.h \
detect-transform-pcrexform.h \
detect-transform-urldecode.h \
detect-ttl.h \
detect-udphdr.h \
detect-uricontent.h \
@ -866,7 +865,6 @@ libsuricata_c_a_SOURCES = \
detect-tos.c \
detect-transform-base64.c \
detect-transform-pcrexform.c \
detect-transform-urldecode.c \
detect-ttl.c \
detect-udphdr.c \
detect-uricontent.c \

1
src/detect-engine-register.c
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@ -216,7 +216,6 @@
#include "detect-engine-content-inspection.h"
#include "detect-transform-pcrexform.h"
#include "detect-transform-urldecode.h"
#include "detect-transform-base64.h"
#include "util-rule-vars.h"

180
src/detect-transform-urldecode.c
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@ -1,180 +0,0 @@
/* Copyright (C) 2020 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Philippe Antoine <p.antoine@catenacyber.fr>
*
* Implements the url_decode transform keyword
*/
#include "suricata-common.h"
#include "detect.h"
#include "detect-engine.h"
#include "detect-engine-prefilter.h"
#include "detect-engine-build.h"
#include "detect-parse.h"
#include "detect-transform-urldecode.h"
#include "util-unittest.h"
#include "util-print.h"
static int DetectTransformUrlDecodeSetup (DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectTransformUrlDecodeRegisterTests(void);
#endif
static void TransformUrlDecode(InspectionBuffer *buffer, void *options);
void DetectTransformUrlDecodeRegister(void)
{
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].name = "url_decode";
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].desc =
"modify buffer to decode urlencoded data before inspection";
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].url = "/rules/transforms.html#url-decode";
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].Transform =
TransformUrlDecode;
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].Setup =
DetectTransformUrlDecodeSetup;
#ifdef UNITTESTS
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].RegisterTests =
DetectTransformUrlDecodeRegisterTests;
#endif
sigmatch_table[DETECT_TRANSFORM_URL_DECODE].flags |= SIGMATCH_NOOPT;
}
/**
* \internal
* \brief Apply the transform keyword to the last pattern match
* \param det_ctx detection engine ctx
* \param s signature
* \param nullstr should be null
* \retval 0 ok
* \retval -1 failure
*/
static int DetectTransformUrlDecodeSetup (DetectEngineCtx *de_ctx, Signature *s, const char *nullstr)
{
SCEnter();
int r = DetectSignatureAddTransform(s, DETECT_TRANSFORM_URL_DECODE, NULL);
SCReturnInt(r);
}
// util function so as to ease reuse sometimes
static bool BufferUrlDecode(const uint8_t *input, const uint32_t input_len, uint8_t *output, uint32_t *output_size)
{
bool changed = false;
uint8_t *oi = output;
//PrintRawDataFp(stdout, input, input_len);
for (uint32_t i = 0; i < input_len; i++) {
if (input[i] == '%') {
if (i + 2 < input_len) {
if ((isxdigit(input[i+1])) && (isxdigit(input[i+2]))) {
// Decode %HH encoding.
*oi = (uint8_t)((input[i + 1] >= 'A' ? ((input[i + 1] & 0xdf) - 'A') + 10
: (input[i + 1] - '0'))
<< 4);
*oi |= (input[i+2] >= 'A' ? ((input[i+2] & 0xdf) - 'A') + 10 : (input[i+2] - '0'));
oi++;
// one more increment before looping
i += 2;
changed = true;
} else {
// leaves incorrect percent
// does not handle unicode %u encoding
*oi++ = input[i];
}
} else {
// leaves trailing incomplete percent
*oi++ = input[i];
}
} else if (input[i] == '+') {
*oi++ = ' ';
changed = true;
} else {
*oi++ = input[i];
}
}
*output_size = oi - output;
return changed;
}
static void TransformUrlDecode(InspectionBuffer *buffer, void *options)
{
uint32_t output_size;
bool changed;
const uint8_t *input = buffer->inspect;
const uint32_t input_len = buffer->inspect_len;
if (input_len == 0) {
return;
}
uint8_t output[input_len]; // we can only shrink
changed = BufferUrlDecode(input, input_len, output, &output_size);
if (changed) {
InspectionBufferCopy(buffer, output, output_size);
}
}
#ifdef UNITTESTS
static int DetectTransformUrlDecodeTest01(void)
{
const uint8_t *input = (const uint8_t *)"Suricata%20is+%27%61wesome%21%27%25%30%30%ZZ%4";
uint32_t input_len = strlen((char *)input);
InspectionBuffer buffer;
InspectionBufferInit(&buffer, 8);
InspectionBufferSetup(NULL, -1, &buffer, input, input_len);
PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);
TransformUrlDecode(&buffer, NULL);
PrintRawDataFp(stdout, buffer.inspect, buffer.inspect_len);
FAIL_IF (buffer.inspect_len != strlen("Suricata is 'awesome!'%00%ZZ%4"));
FAIL_IF (memcmp(buffer.inspect, "Suricata is 'awesome!'%00%ZZ%4", buffer.inspect_len) != 0);
InspectionBufferFree(&buffer);
PASS;
}
static int DetectTransformUrlDecodeTest02(void)
{
const char rule[] = "alert http any any -> any any (http.request_body; url_decode; content:\"mail=test@oisf.net\"; sid:1;)";
ThreadVars th_v;
DetectEngineThreadCtx *det_ctx = NULL;
memset(&th_v, 0, sizeof(th_v));
DetectEngineCtx *de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
Signature *s = DetectEngineAppendSig(de_ctx, rule);
FAIL_IF_NULL(s);
SigGroupBuild(de_ctx);
DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);
DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);
DetectEngineCtxFree(de_ctx);
PASS;
}
static void DetectTransformUrlDecodeRegisterTests(void)
{
UtRegisterTest("DetectTransformUrlDecodeTest01",
DetectTransformUrlDecodeTest01);
UtRegisterTest("DetectTransformUrlDecodeTest02",
DetectTransformUrlDecodeTest02);
}
#endif

30
src/detect-transform-urldecode.h
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@ -1,30 +0,0 @@
/* Copyright (C) 2020 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Philippe Antoine <p.antoine@catenacyber.fr>
*/
#ifndef SURICATA_DETECT_TRANSFORM_URLDECODE_H
#define SURICATA_DETECT_TRANSFORM_URLDECODE_H
/* prototypes */
void DetectTransformUrlDecodeRegister (void);
#endif /* SURICATA_DETECT_TRANSFORM_URLDECODE_H */
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