/*
Non-writable memory test case
Copyright(c) 2015 Chris Eagle
This program is free software; you can redistribute it and/or
modify it 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
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <string.h>
#include <unicorn/unicorn.h>
const uint8_t PROGRAM[] =
"\xeb\x1a\x58\x83\xc0\x04\x83\xe0\xfc\x83\xc0\x01\xc7\x00\x78\x56"
"\x34\x12\x83\xc0\x07\xc7\x00\x21\x43\x65\x87\x90\xe8\xe1\xff\xff"
"\xff" "xxxxAAAAxxxBBBB";
// total size: 33 bytes
/*
jmp short bottom
top:
pop eax
add eax, 4
and eax, 0xfffffffc
add eax, 1 ; unaligned
mov dword [eax], 0x12345678 ; try to write into code section
add eax, 7 ; aligned
mov dword [eax], 0x87654321 ; try to write into code section
nop
bottom:
call top
*/
// callback for tracing instruction
/*static void hook_code(uc_engine *uc, uint64_t address, uint32_t size, void *user_data)
{
uint32_t esp;
printf(">>> Tracing instruction at 0x%"PRIx64 ", instruction size = 0x%x\n", address, size);
uc_reg_read(uc, UC_X86_REG_ESP, &esp);
printf(">>> --- ESP is 0x%x\n", esp);
}
*/
// callback for tracing memory access (READ or WRITE)
static bool hook_mem_invalid(uc_engine *uc, uc_mem_type type,
uint64_t address, int size, int64_t value, void *user_data)
{
uint32_t esp;
uc_reg_read(uc, UC_X86_REG_ESP, &esp);
switch(type) {
default:
// return false to indicate we want to stop emulation
return false;
case UC_MEM_WRITE:
//if this is a push, esp has not been adjusted yet
if (esp == (address + size)) {
uint32_t upper;
upper = (esp + 0xfff) & ~0xfff;
printf(">>> Stack appears to be missing at 0x%"PRIx64 ", allocating now\n", address);
// map this memory in with 2MB in size
uc_mem_map(uc, upper - 0x8000, 0x8000, UC_PROT_READ | UC_PROT_WRITE);
// return true to indicate we want to continue
return true;
}
printf(">>> Missing memory is being WRITTEN at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n",
address, size, value);
return false;
case UC_MEM_WRITE_PROT:
printf(">>> RO memory is being WRITTEN at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n",
address, size, value);
return false;
}
}
#define STACK 0x500000
#define STACK_SIZE 0x5000
int main(int argc, char **argv, char **envp)
{
uc_engine *uc;
uc_hook trace1;
uc_err err;
uint8_t bytes[8];
uint32_t esp;
int map_stack = 0;
if (argc == 2 && strcmp(argv[1], "--map-stack") == 0) {
map_stack = 1;
}
printf("Memory mapping test\n");
// Initialize emulator in X86-32bit mode
err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc);
if (err) {
printf("Failed on uc_open() with error returned: %u\n", err);
return 1;
}
uc_mem_map(uc, 0x100000, 0x1000, UC_PROT_ALL);
uc_mem_map(uc, 0x200000, 0x2000, UC_PROT_ALL);
uc_mem_map(uc, 0x300000, 0x3000, UC_PROT_ALL);
uc_mem_map(uc, 0x400000, 0x4000, UC_PROT_READ);
if (map_stack) {
printf("Pre-mapping stack\n");
uc_mem_map(uc, STACK, STACK_SIZE, UC_PROT_READ | UC_PROT_WRITE);
} else {
printf("Mapping stack on first invalid memory access\n");
}
esp = STACK + STACK_SIZE;
uc_reg_write(uc, UC_X86_REG_ESP, &esp);
// write machine code to be emulated to memory
if (uc_mem_write(uc, 0x400000, PROGRAM, sizeof(PROGRAM))) {
printf("Failed to write emulation code to memory, quit!\n");
return 2;
} else {
printf("Allowed to write to read only memory via uc_mem_write\n");
}
//uc_hook_add(uc, &trace2, UC_HOOK_CODE, hook_code, NULL, 0x400000, 0x400fff);
// intercept invalid memory events
uc_hook_add(uc, &trace1, UC_HOOK_MEM_WRITE_UNMAPPED | UC_HOOK_MEM_WRITE_PROT, hook_mem_invalid, NULL, 1, 0);
// emulate machine code in infinite time
printf("BEGIN execution - 1\n");
err = uc_emu_start(uc, 0x400000, 0x400000 + sizeof(PROGRAM), 0, 10);
if (err) {
printf("Expected failue on uc_emu_start() with error returned %u: %s\n",
err, uc_strerror(err));
} else {
printf("UNEXPECTED uc_emu_start returned UC_ERR_OK\n");
}
printf("END execution - 1\n");
// emulate machine code in infinite time
printf("BEGIN execution - 2\n");
//update eax to point to aligned memory (same as add eax,7 above)
uint32_t eax = 0x40002C;
uc_reg_write(uc, UC_X86_REG_EAX, &eax);
//resume execution at the mov dword [eax], 0x87654321
//to test an aligned write as well
err = uc_emu_start(uc, 0x400015, 0x400000 + sizeof(PROGRAM), 0, 2);
if (err) {
printf("Expected failure on uc_emu_start() with error returned %u: %s\n",
err, uc_strerror(err));
} else {
printf("UNEXPECTED uc_emu_start returned UC_ERR_OK\n");
}
printf("END execution - 2\n");
printf("Verifying content at 0x400025 is unchanged\n");
if (!uc_mem_read(uc, 0x400025, bytes, 4)) {
printf(">>> Read 4 bytes from [0x%x] = 0x%x\n", (uint32_t)0x400025, *(uint32_t*) bytes);
if (0x41414141 != *(uint32_t*) bytes) {
printf("ERROR content in read only memory changed\n");
} else {
printf("SUCCESS content in read only memory unchanged\n");
}
} else {
printf(">>> Failed to read 4 bytes from [0x%x]\n", (uint32_t)(esp - 4));
return 4;
}
printf("Verifying content at 0x40002C is unchanged\n");
if (!uc_mem_read(uc, 0x40002C, bytes, 4)) {
printf(">>> Read 4 bytes from [0x%x] = 0x%x\n", (uint32_t)0x40002C, *(uint32_t*) bytes);
if (0x42424242 != *(uint32_t*) bytes) {
printf("ERROR content in read only memory changed\n");
} else {
printf("SUCCESS content in read only memory unchanged\n");
}
} else {
printf(">>> Failed to read 4 bytes from [0x%x]\n", (uint32_t)(esp - 4));
return 4;
}
printf("Verifying content at bottom of stack is readable and correct\n");
if (!uc_mem_read(uc, esp - 4, bytes, 4)) {
printf(">>> Read 4 bytes from [0x%x] = 0x%x\n", (uint32_t)(esp - 4), *(uint32_t*) bytes);
} else {
printf(">>> Failed to read 4 bytes from [0x%x]\n", (uint32_t)(esp - 4));
return 4;
}
uc_close(uc);
return 0;
}