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curl/tests/fuzz/curl_fuzzer.cc

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2017, Max Dymond, <cmeister2@gmail.com>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <curl/curl.h>
#include "curl_fuzzer.h"
/**
* Fuzzing entry point. This function is passed a buffer containing a test
* case. This test case should drive the CURL API into making a request.
*/
extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
int rc = 0;
int tlv_rc;
FUZZ_DATA fuzz;
TLV tlv;
/* Have to set all fields to zero before getting to the terminate function */
memset(&fuzz, 0, sizeof(FUZZ_DATA));
if(size < sizeof(TLV_RAW)) {
/* Not enough data for a single TLV - don't continue */
goto EXIT_LABEL;
}
/* Try to initialize the fuzz data */
FTRY(fuzz_initialize_fuzz_data(&fuzz, data, size));
for(tlv_rc = fuzz_get_first_tlv(&fuzz, &tlv);
tlv_rc == 0;
tlv_rc = fuzz_get_next_tlv(&fuzz, &tlv)) {
/* Have the TLV in hand. Parse the TLV. */
fuzz_parse_tlv(&fuzz, &tlv);
}
if(tlv_rc != TLV_RC_NO_MORE_TLVS) {
/* A TLV call failed. Can't continue. */
goto EXIT_LABEL;
}
/* Do the CURL stuff! */
curl_easy_perform(fuzz.easy);
EXIT_LABEL:
fuzz_terminate_fuzz_data(&fuzz);
/* This function must always return 0. Non-zero codes are reserved. */
return 0;
}
/**
* Utility function to convert 4 bytes to a u32 predictably.
*/
uint32_t to_u32(uint8_t b[4])
{
uint32_t u;
u = (b[0] << 24) + (b[1] << 16) + (b[2] << 8) + b[3];
return u;
}
/**
* Utility function to convert 2 bytes to a u16 predictably.
*/
uint16_t to_u16(uint8_t b[2])
{
uint16_t u;
u = (b[0] << 8) + b[1];
return u;
}
/**
* Initialize the local fuzz data structure.
*/
int fuzz_initialize_fuzz_data(FUZZ_DATA *fuzz,
const uint8_t *data,
size_t data_len)
{
int rc = 0;
/* Initialize the fuzz data. */
memset(fuzz, 0, sizeof(FUZZ_DATA));
/* Create an easy handle. This will have all of the settings configured on
it. */
fuzz->easy = curl_easy_init();
FCHECK(fuzz->easy != NULL);
/* Set some standard options on the CURL easy handle. We need to override the
socket function so that we create our own sockets to present to CURL. */
FTRY(curl_easy_setopt(fuzz->easy,
CURLOPT_OPENSOCKETFUNCTION,
fuzz_open_socket));
FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_OPENSOCKETDATA, fuzz));
/* In case something tries to set a socket option, intercept this. */
FTRY(curl_easy_setopt(fuzz->easy,
CURLOPT_SOCKOPTFUNCTION,
fuzz_sockopt_callback));
/* Can enable verbose mode */
/* FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_VERBOSE, 1L)); */
/* Set up the state parser */
fuzz->state.data = data;
fuzz->state.data_len = data_len;
EXIT_LABEL:
return rc;
}
/**
* Terminate the fuzz data structure, including freeing any allocated memory.
*/
void fuzz_terminate_fuzz_data(FUZZ_DATA *fuzz)
{
fuzz_free((void **)&fuzz->url);
fuzz_free((void **)&fuzz->username);
fuzz_free((void **)&fuzz->password);
fuzz_free((void **)&fuzz->postfields);
if(fuzz->easy != NULL) {
curl_easy_cleanup(fuzz->easy);
fuzz->easy = NULL;
}
}
/**
* If a pointer has been allocated, free that pointer.
*/
void fuzz_free(void **ptr)
{
if(*ptr != NULL) {
free(*ptr);
*ptr = NULL;
}
}
/**
* Function for providing a socket to CURL already primed with data.
*/
static curl_socket_t fuzz_open_socket(void *ptr,
curlsocktype purpose,
struct curl_sockaddr *address)
{
FUZZ_DATA *fuzz = (FUZZ_DATA *)ptr;
int fds[2];
curl_socket_t server_fd;
curl_socket_t client_fd;
/* Handle unused parameters */
(void)purpose;
(void)address;
if(socketpair(AF_UNIX, SOCK_STREAM, 0, fds)) {
/* Failed to create a pair of sockets. */
return CURL_SOCKET_BAD;
}
server_fd = fds[0];
client_fd = fds[1];
/* Try and write the response data to the server file descriptor so the
client can read it. */
if(write(server_fd,
fuzz->rsp1_data,
fuzz->rsp1_data_len) != (ssize_t)fuzz->rsp1_data_len) {
/* Failed to write the data. */
return CURL_SOCKET_BAD;
}
if(shutdown(server_fd, SHUT_WR)) {
return CURL_SOCKET_BAD;
}
return client_fd;
}
/**
* Callback function for setting socket options on the sockets created by
* fuzz_open_socket. In our testbed the sockets are "already connected".
*/
static int fuzz_sockopt_callback(void *ptr,
curl_socket_t curlfd,
curlsocktype purpose)
{
(void)ptr;
(void)curlfd;
(void)purpose;
return CURL_SOCKOPT_ALREADY_CONNECTED;
}
/**
* TLV access function - gets the first TLV from a data stream.
*/
int fuzz_get_first_tlv(FUZZ_DATA *fuzz,
TLV *tlv)
{
/* Reset the cursor. */
fuzz->state.data_pos = 0;
return fuzz_get_tlv_comn(fuzz, tlv);
}
/**
* TLV access function - gets the next TLV from a data stream.
*/
int fuzz_get_next_tlv(FUZZ_DATA *fuzz,
TLV *tlv)
{
/* Advance the cursor by the full length of the previous TLV. */
fuzz->state.data_pos += sizeof(TLV_RAW) + tlv->length;
/* Work out if there's a TLV's worth of data to read */
if(fuzz->state.data_pos + sizeof(TLV_RAW) > fuzz->state.data_len) {
/* No more TLVs to parse */
return TLV_RC_NO_MORE_TLVS;
}
return fuzz_get_tlv_comn(fuzz, tlv);
}
/**
* Common TLV function for accessing TLVs in a data stream.
*/
int fuzz_get_tlv_comn(FUZZ_DATA *fuzz,
TLV *tlv)
{
int rc = 0;
size_t data_offset;
TLV_RAW *raw;
/* Start by casting the data stream to a TLV. */
raw = (TLV_RAW *)&fuzz->state.data[fuzz->state.data_pos];
data_offset = fuzz->state.data_pos + sizeof(TLV_RAW);
/* Set the TLV values. */
tlv->type = to_u16(raw->raw_type);
tlv->length = to_u32(raw->raw_length);
tlv->value = &fuzz->state.data[data_offset];
/* Sanity check that the TLV length is ok. */
if(data_offset + tlv->length > fuzz->state.data_len) {
rc = TLV_RC_SIZE_ERROR;
}
return rc;
}
/**
* Do different actions on the CURL handle for different received TLVs.
*/
int fuzz_parse_tlv(FUZZ_DATA *fuzz, TLV *tlv)
{
int rc;
switch(tlv->type) {
case TLV_TYPE_URL:
FCHECK(fuzz->url == NULL);
fuzz->url = fuzz_tlv_to_string(tlv);
FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_URL, fuzz->url));
break;
case TLV_TYPE_RESPONSE1:
/* The pointers in the TLV will always be valid as long as the fuzz data
is in scope, which is the entirety of this file. */
fuzz->rsp1_data = tlv->value;
fuzz->rsp1_data_len = tlv->length;
break;
case TLV_TYPE_USERNAME:
FCHECK(fuzz->username == NULL);
fuzz->username = fuzz_tlv_to_string(tlv);
FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_USERNAME, fuzz->username));
break;
case TLV_TYPE_PASSWORD:
FCHECK(fuzz->password == NULL);
fuzz->password = fuzz_tlv_to_string(tlv);
FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_PASSWORD, fuzz->password));
break;
case TLV_TYPE_POSTFIELDS:
FCHECK(fuzz->postfields == NULL);
fuzz->postfields = fuzz_tlv_to_string(tlv);
FTRY(curl_easy_setopt(fuzz->easy, CURLOPT_POSTFIELDS, fuzz->postfields));
break;
default:
/* The fuzzer generates lots of unknown TLVs, so don't do anything if
the TLV isn't known. */
break;
}
rc = 0;
EXIT_LABEL:
return rc;
}
/**
* Converts a TLV data and length into an allocated string.
*/
char *fuzz_tlv_to_string(TLV *tlv)
{
char *tlvstr;
/* Allocate enough space, plus a null terminator */
tlvstr = (char *)malloc(tlv->length + 1);
if(tlvstr != NULL) {
memcpy(tlvstr, tlv->value, tlv->length);
tlvstr[tlv->length] = 0;
}
return tlvstr;
}
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