375 lines
11 KiB
C
375 lines
11 KiB
C
/*
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Sample use of uc_mem_unmap, uc_mem_protect, and memory permissions
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Copyright(c) 2015 Chris Eagle
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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version 2 as published by the Free Software Foundation.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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USA.
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*/
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#define __STDC_FORMAT_MACROS
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#include <unicorn/unicorn.h>
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#include <string.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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static int insts_executed;
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// callback for tracing instructions, detect HLT and terminate emulation
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static void hook_code(uc_engine *uc, uint64_t addr, uint32_t size,
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void *user_data)
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{
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uint8_t opcode;
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unsigned char buf[256];
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insts_executed++;
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if (uc_mem_read(uc, addr, buf, size) != UC_ERR_OK) {
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printf("not ok - uc_mem_read fail during hook_code callback, addr: "
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"0x%" PRIx64 "\n",
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addr);
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if (uc_emu_stop(uc) != UC_ERR_OK) {
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printf("not ok - uc_emu_stop fail during hook_code callback, addr: "
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"0x%" PRIx64 "\n",
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addr);
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_exit(-1);
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}
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}
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opcode = buf[0];
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switch (opcode) {
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case 0x41: // inc ecx
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if (uc_mem_protect(uc, 0x101000, 0x1000, UC_PROT_READ) != UC_ERR_OK) {
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printf("not ok - uc_mem_protect fail during hook_code callback, "
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"addr: 0x%" PRIx64 "\n",
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addr);
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_exit(-1);
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}
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break;
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case 0x42: // inc edx
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if (uc_mem_unmap(uc, 0x101000, 0x1000) != UC_ERR_OK) {
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printf("not ok - uc_mem_unmap fail during hook_code callback, "
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"addr: 0x%" PRIx64 "\n",
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addr);
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_exit(-1);
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}
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break;
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case 0xf4: // hlt
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if (uc_emu_stop(uc) != UC_ERR_OK) {
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printf("not ok - uc_emu_stop fail during hook_code callback, addr: "
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"0x%" PRIx64 "\n",
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addr);
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_exit(-1);
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}
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break;
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default: // all others
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break;
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}
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}
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// callback for tracing invalid memory access (READ/WRITE/EXEC)
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static bool hook_mem_invalid(uc_engine *uc, uc_mem_type type, uint64_t addr,
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int size, int64_t value, void *user_data)
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{
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switch (type) {
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default:
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printf("not ok - UC_HOOK_MEM_INVALID type: %d at 0x%" PRIx64 "\n", type,
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addr);
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return false;
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case UC_MEM_READ_UNMAPPED:
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printf("not ok - Read from invalid memory at 0x%" PRIx64
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", data size = %u\n",
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addr, size);
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return false;
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case UC_MEM_WRITE_UNMAPPED:
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printf("not ok - Write to invalid memory at 0x%" PRIx64
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", data size = %u, data value = 0x%" PRIx64 "\n",
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addr, size, value);
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return false;
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case UC_MEM_FETCH_PROT:
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printf("not ok - Fetch from non-executable memory at 0x%" PRIx64 "\n",
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addr);
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return false;
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case UC_MEM_WRITE_PROT:
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printf("not ok - Write to non-writeable memory at 0x%" PRIx64
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", data size = %u, data value = 0x%" PRIx64 "\n",
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addr, size, value);
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return false;
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case UC_MEM_READ_PROT:
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printf("not ok - Read from non-readable memory at 0x%" PRIx64
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", data size = %u\n",
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addr, size);
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return false;
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}
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}
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static void do_nx_demo(bool cause_fault)
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{
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uc_engine *uc;
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uc_hook trace1, trace2;
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uc_err err;
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uint8_t code_buf[0x3000];
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insts_executed = 0;
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printf("===================================\n");
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printf("# Example of marking memory NX (%s)\n",
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cause_fault ? "faulting" : "non-faulting");
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// Initialize emulator in X86-32bit mode
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err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc);
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if (err) {
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printf("not ok - Failed on uc_open() with error returned: %u\n", err);
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return;
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}
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uc_mem_map(uc, 0x100000, 0x3000, UC_PROT_READ | UC_PROT_EXEC);
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/*
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bits 32
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page0: @0
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times 4091 inc eax
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jmp page2
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page1: @1000
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times 4095 inc eax (or INC ECX)
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hlt
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page2: @2000
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jmp page1
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*/
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memset(code_buf, 0x40, sizeof(code_buf)); // fill with inc eax
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memcpy(code_buf + 0x1000 - 5, "\xe9\x00\x10\x00\x00",
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5); // jump to 0x102000
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memcpy(code_buf + 0x2000, "\xe9\xfb\xef\xff\xff", 5); // jump to 0x101000
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code_buf[0x1fff] = 0xf4; // hlt
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if (cause_fault) {
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// insert instruction to trigger U_PROT_EXEC change (see hook_code
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// function)
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code_buf[0x1000] = 0x41; // inc ecx at page1
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}
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// write machine code to be emulated to memory
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if (uc_mem_write(uc, 0x100000, code_buf, sizeof(code_buf))) {
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printf("not ok - Failed to write emulation code to memory, quit!\n");
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return;
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}
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// intercept code and invalid memory events
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if (uc_hook_add(uc, &trace2, UC_HOOK_CODE, hook_code, NULL, 1, 0) !=
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UC_ERR_OK ||
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uc_hook_add(uc, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL, 1,
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0) != UC_ERR_OK) {
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printf("not ok - Failed to install hooks\n");
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return;
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}
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// emulate machine code until told to stop by hook_code
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printf("BEGINNING EXECUTION\n");
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err = uc_emu_start(uc, 0x100000, 0x103000, 0, 0);
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if (err != UC_ERR_OK) {
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printf("not ok - Failure on uc_emu_start() with error %u: %s\n", err,
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uc_strerror(err));
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printf("FAILED EXECUTION\n");
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} else {
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printf("SUCCESSFUL EXECUTION\n");
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}
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printf("Executed %d instructions\n\n", insts_executed);
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uc_close(uc);
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}
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static void nx_test()
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{
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printf("NX demo - step 1: show that code runs to completion\n");
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do_nx_demo(false);
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printf("NX demo - step 2: show that code fails without UC_PROT_EXEC\n");
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do_nx_demo(true);
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}
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static const uint8_t WRITE_DEMO[] =
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"\x90\xc7\x05\x00\x20\x10\x00\x78\x56\x34\x12\xc7\x05\xfc\x0f\x10"
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"\x00\x78\x56\x34\x12\xc7\x05\x00\x10\x10\x00\x21\x43\x65\x87";
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static void do_perms_demo(bool change_perms)
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{
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uc_engine *uc;
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uc_hook trace1, trace2;
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uc_err err;
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uint8_t code_buf[0x3000];
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insts_executed = 0;
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printf("===================================\n");
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printf("# Example of manipulating memory permissions\n");
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// Initialize emulator in X86-32bit mode
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err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc);
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if (err) {
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printf("not ok - Failed on uc_open() with error returned: %u\n", err);
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return;
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}
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uc_mem_map(uc, 0x100000, 0x3000, UC_PROT_ALL);
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/*
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bits 32
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nop
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mov dword [0x102000], 0x12345678
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mov dword [0x100ffc], 0x12345678
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mov dword [0x101000], 0x87654321 ; crashing case crashes here
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times 1000 nop
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hlt
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*/
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memcpy(code_buf, WRITE_DEMO, sizeof(WRITE_DEMO) - 1);
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memset(code_buf + sizeof(WRITE_DEMO) - 1, 0x90, 1000);
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code_buf[sizeof(WRITE_DEMO) - 1 + 1000] = 0xf4; // hlt
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if (change_perms) {
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// write protect memory area [0x101000, 0x101fff]. see hook_code
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// function
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code_buf[0] = 0x41; // inc ecx
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}
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// write machine code to be emulated to memory
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if (uc_mem_write(uc, 0x100000, code_buf, sizeof(code_buf))) {
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printf("not ok - Failed to write emulation code to memory, quit!\n");
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return;
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}
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// intercept code and invalid memory events
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if (uc_hook_add(uc, &trace2, UC_HOOK_CODE, hook_code, NULL, 1, 0) !=
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UC_ERR_OK ||
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uc_hook_add(uc, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL, 1,
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0) != UC_ERR_OK) {
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printf("not ok - Failed to install hooks\n");
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return;
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}
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// emulate machine code until told to stop by hook_code
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printf("BEGINNING EXECUTION\n");
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err = uc_emu_start(uc, 0x100000, 0x103000, 0, 0);
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if (err != UC_ERR_OK) {
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printf("FAILED EXECUTION\n");
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printf("not ok - Failure on uc_emu_start() with error %u: %s\n", err,
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uc_strerror(err));
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} else {
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printf("SUCCESSFUL EXECUTION\n");
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}
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printf("Executed %d instructions\n\n", insts_executed);
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uc_close(uc);
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}
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static void perms_test()
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{
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printf("Permissions demo - step 1: show that area is writeable\n");
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do_perms_demo(false);
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printf("Permissions demo - step 2: show that code fails when memory marked "
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"unwriteable\n");
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do_perms_demo(true);
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}
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static void do_unmap_demo(bool do_unmap)
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{
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uc_engine *uc;
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uc_hook trace1, trace2;
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uc_err err;
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uint8_t code_buf[0x3000];
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insts_executed = 0;
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printf("===================================\n");
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printf("# Example of unmapping memory\n");
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// Initialize emulator in X86-32bit mode
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err = uc_open(UC_ARCH_X86, UC_MODE_32, &uc);
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if (err) {
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printf("not ok - Failed on uc_open() with error returned: %u\n", err);
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return;
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}
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uc_mem_map(uc, 0x100000, 0x3000, UC_PROT_ALL);
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/*
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bits 32
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nop
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mov dword [0x102000], 0x12345678
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mov dword [0x100ffc], 0x12345678
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mov dword [0x101000], 0x87654321 ; crashing case crashes here
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times 1000 nop
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hlt
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*/
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memcpy(code_buf, WRITE_DEMO, sizeof(WRITE_DEMO) - 1);
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memset(code_buf + sizeof(WRITE_DEMO) - 1, 0x90, 1000);
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code_buf[sizeof(WRITE_DEMO) - 1 + 1000] = 0xf4; // hlt
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if (do_unmap) {
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// unmap memory area [0x101000, 0x101fff]. see hook_code function
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code_buf[0] = 0x42; // inc edx (see hook_code function)
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}
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// write machine code to be emulated to memory
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if (uc_mem_write(uc, 0x100000, code_buf, 0x1000)) {
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printf("not ok - Failed to write emulation code to memory, quit!\n");
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return;
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}
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// intercept code and invalid memory events
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if (uc_hook_add(uc, &trace2, UC_HOOK_CODE, hook_code, NULL, 1, 0) !=
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UC_ERR_OK ||
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uc_hook_add(uc, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL, 1,
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0) != UC_ERR_OK) {
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printf("not ok - Failed to install hooks\n");
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return;
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}
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// emulate machine code until told to stop by hook_code
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printf("BEGINNING EXECUTION\n");
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err = uc_emu_start(uc, 0x100000, 0x103000, 0, 0);
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if (err != UC_ERR_OK) {
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printf("FAILED EXECUTION\n");
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printf("not ok - Failure on uc_emu_start() with error %u: %s\n", err,
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uc_strerror(err));
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} else {
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printf("SUCCESSFUL EXECUTION\n");
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}
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printf("Executed %d instructions\n\n", insts_executed);
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uc_close(uc);
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}
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static void unmap_test()
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{
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printf("Unmap demo - step 1: show that area is writeable\n");
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do_unmap_demo(false);
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printf(
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"Unmap demo - step 2: show that code fails when memory is unmapped\n");
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do_unmap_demo(true);
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}
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int main(int argc, char **argv, char **envp)
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{
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nx_test();
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perms_test();
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unmap_test();
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return 0;
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}
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