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disassembler.c
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disassembler.c
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/*
Copyright (C) 2017 Sergej Schumilo
This file is part of QEMU-PT (kAFL).
QEMU-PT is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
QEMU-PT 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 QEMU-PT. If not, see <http://www.gnu.org/licenses/>.
*/
#include "pt/disassembler.h"
#include "pt/memory_access.h"
#define LOOKUP_TABLES 5
#define IGN_MOD_RM 0
#define IGN_OPODE_PREFIX 0
#define MODRM_REG(x) (x << 3)
#define MODRM_AND 0b00111000
/* http://stackoverflow.com/questions/29600668/what-meaning-if-any-does-the-mod-r-m-byte-carry-for-the-unconditional-jump-ins */
/* conditional branch */
cofi_ins cb_lookup[] = {
{X86_INS_JAE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JA, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JBE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JB, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JCXZ, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JECXZ, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JGE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JG, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JLE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JL, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JNE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JNO, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JNP, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JNS, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JO, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JP, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JRCXZ, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JS, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_LOOP, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_LOOPE, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_LOOPNE, IGN_MOD_RM, IGN_OPODE_PREFIX},
};
/* unconditional direct branch */
cofi_ins udb_lookup[] = {
{X86_INS_JMP, IGN_MOD_RM, 0xe9},
{X86_INS_JMP, IGN_MOD_RM, 0xeb},
{X86_INS_CALL, IGN_MOD_RM, 0xe8},
};
/* indirect branch */
cofi_ins ib_lookup[] = {
{X86_INS_JMP, MODRM_REG(4), 0xff},
{X86_INS_CALL, MODRM_REG(2), 0xff},
};
/* near ret */
cofi_ins nr_lookup[] = {
{X86_INS_RET, IGN_MOD_RM, 0xc3},
{X86_INS_RET, IGN_MOD_RM, 0xc2},
};
/* far transfers */
cofi_ins ft_lookup[] = {
{X86_INS_INT3, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_INT, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_INT1, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_INTO, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_IRET, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_IRETD, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_IRETQ, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_JMP, IGN_MOD_RM, 0xea},
{X86_INS_JMP, MODRM_REG(5), 0xff},
{X86_INS_CALL, IGN_MOD_RM, 0x9a},
{X86_INS_CALL, MODRM_REG(3), 0xff},
{X86_INS_RET, IGN_MOD_RM, 0xcb},
{X86_INS_RET, IGN_MOD_RM, 0xca},
{X86_INS_SYSCALL, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_SYSENTER, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_SYSEXIT, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_SYSRET, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_VMLAUNCH, IGN_MOD_RM, IGN_OPODE_PREFIX},
{X86_INS_VMRESUME, IGN_MOD_RM, IGN_OPODE_PREFIX},
};
uint16_t cmp_lookup[] = {
X86_INS_CMP,
X86_INS_CMPPD,
X86_INS_CMPPS,
X86_INS_CMPSB,
X86_INS_CMPSD,
X86_INS_CMPSQ,
X86_INS_CMPSS,
X86_INS_CMPSW,
X86_INS_CMPXCHG16B,
X86_INS_CMPXCHG,
X86_INS_CMPXCHG8B,
};
cofi_ins* lookup_tables[] = {
cb_lookup,
udb_lookup,
ib_lookup,
nr_lookup,
ft_lookup,
};
uint8_t lookup_table_sizes[] = {
22,
3,
2,
2,
19
};
/* ===== kAFL disassembler cofi list ===== */
static cofi_list* create_list_head(void){
cofi_list* head = malloc(sizeof(cofi_list));
if (head != NULL){
head->list_ptr = NULL;
head->cofi_ptr = NULL;
head->cofi = NULL;
return head;
}
return NULL;
}
static void free_list(cofi_list* head){
cofi_list *tmp1, *tmp2;
tmp1 = head;
while (1){
tmp2 = tmp1;
if(tmp1 == NULL){
break;
}
tmp1 = tmp1->list_ptr;
if (tmp2->cofi != NULL){
free(tmp2->cofi);
}
free(tmp2);
}
}
static cofi_list* new_list_element(cofi_list* predecessor, cofi_header* cofi){
if(predecessor){
cofi_list* next = malloc(sizeof(cofi_list));
if (next){
predecessor->list_ptr = next;
next->list_ptr = NULL;
next->cofi_ptr = NULL;
next->cofi = cofi;
return next;
}
}
return NULL;
}
static void edit_cofi_ptr(cofi_list* element, cofi_list* target){
if (element){
element->cofi_ptr = target;
}
}
/* ===== kAFL disassembler hashmap ===== */
cofi_list *tmp_cofi;
static void map_put(disassembler_t* self, uint64_t addr, uint64_t ref){
int ret;
khiter_t k;
k = kh_put(ADDR0, self->map, addr, &ret);
kh_value(self->map, k) = ref;
}
static int map_get(disassembler_t* self, uint64_t addr, uint64_t* ref){
khiter_t k;
k = kh_get(ADDR0, self->map, addr);
if(k != kh_end(self->map)){
*ref = kh_value(self->map, k);
return 0;
}
return 1;
}
/* ===== kAFL disassembler engine ===== */
static inline uint64_t fast_strtoull(const char *hexstring){
uint64_t result = 0;
uint8_t i = 0;
if (hexstring[1] == 'x' || hexstring[1] == 'X')
i = 2;
for (; hexstring[i]; i++)
result = (result << 4) + (9 * (hexstring[i] >> 6) + (hexstring[i] & 017));
return result;
}
static inline uint64_t hex_to_bin(char* str){
//return (uint64_t)strtoull(str, NULL, 16);
return fast_strtoull(str);
}
static cofi_type opcode_analyzer(disassembler_t* self, cs_insn *ins){
uint8_t i, j;
cs_x86 details = ins->detail->x86;
for (i = 0; i < LOOKUP_TABLES; i++){
for (j = 0; j < lookup_table_sizes[i]; j++){
if (ins->id == lookup_tables[i][j].opcode){
/* check MOD R/M */
if (lookup_tables[i][j].modrm != IGN_MOD_RM && lookup_tables[i][j].modrm != (details.modrm & MODRM_AND))
continue;
/* check opcode prefix byte */
if (lookup_tables[i][j].opcode_prefix != IGN_OPODE_PREFIX && lookup_tables[i][j].opcode_prefix != details.opcode[0])
continue;
#ifdef DEBUG
/* found */
printf("%lx (%d)\t%s\t%s\t\t", ins->address, i, ins->mnemonic, ins->op_str);
print_string_hex(" \t", ins->bytes, ins->size);
#endif
return i;
}
}
}
return NO_COFI_TYPE;
}
static cofi_list* analyse_assembly(disassembler_t* self, uint64_t base_address, bool across_page)
{
csh handle;
cs_insn *insn;
cofi_type type;
cofi_header* tmp = NULL;
uint64_t tmp_list_element = 0;
bool last_nop = false, no_munmap = true;
uint64_t total = 0;
uint64_t cofi = 0;
const uint8_t* code = mmap_virtual_memory(base_address, self->cpu);
uint8_t tmp_code[x86_64_PAGE_SIZE*2];
size_t code_size = x86_64_PAGE_SIZE - (base_address & x86_64_PAGE_OFF_MASK);
uint64_t address = base_address;
cofi_list* predecessor = NULL;
cofi_list* first = NULL;
if (cs_open(CS_ARCH_X86, CS_MODE_64, &handle) != CS_ERR_OK)
return NULL;
cs_option(handle, CS_OPT_DETAIL, CS_OPT_ON);
insn = cs_malloc(handle);
if (!code) {
printf("Fatal error 1 in analyse_assembly.\n");
asm("int $3\r\n");
}
if (across_page) {
/*
* We must parse instructions in two consecutive pages.
* */
code_size = x86_64_PAGE_SIZE*2 - (address & x86_64_PAGE_OFF_MASK);
if (!read_virtual_memory(address, tmp_code, code_size, self->cpu)) {
printf("Fatal error 2 in analyse_assembly.\n");
asm("int $3\r\n");
}
if (no_munmap) {
munmap_virtual_memory((void *)code, self->cpu);
no_munmap = false;
}
code = tmp_code;
}
while (cs_disasm_iter(handle, &code, &code_size, &address, insn)) {
if (insn->address > self->max_addr){
break;
}
type = opcode_analyzer(self, insn);
total++;
if (self->debug){
printf("%lx:\t(%d)\t%s\t%s\t\t\n", insn->address, type, insn->mnemonic, insn->op_str);
}
if (!last_nop){
tmp = malloc(sizeof(cofi_header));
tmp->type = NO_COFI_TYPE;
tmp->ins_addr = 0;
tmp->target_addr = 0;
if (cofi)
predecessor = self->list_element;
self->list_element = new_list_element(self->list_element, tmp);
edit_cofi_ptr(predecessor, self->list_element);
}
if (!map_get(self, insn->address, &tmp_list_element)){
if(((cofi_list *)tmp_list_element)->cofi_ptr){
edit_cofi_ptr(self->list_element, (cofi_list *)tmp_list_element);
//printf("EDIT COFI PTR (%p %p %p %d)\n", list_element, (cofi_list*)tmp_list_element, list_element->cofi, list_element->cofi->type);
break;
} else {
self->list_element = (cofi_list *)tmp_list_element;
}
}
if (type != NO_COFI_TYPE){
cofi++;
last_nop = false;
tmp->type = type;
tmp->ins_addr = insn->address;
tmp->ins_len = (uint64_t)code - (uint64_t)insn->address;
if (type == COFI_TYPE_CONDITIONAL_BRANCH || type == COFI_TYPE_UNCONDITIONAL_DIRECT_BRANCH){
tmp->target_addr = hex_to_bin(insn->op_str);
} else {
tmp->target_addr = 0;
}
self->list_element->cofi = tmp;
map_put(self, tmp->ins_addr, (uint64_t)(self->list_element));
} else {
last_nop = true;
self->list_element->cofi->ins_addr = insn->address;
map_put(self, insn->address, (uint64_t)(self->list_element));
}
if (!first){
first = self->list_element;
}
}
cs_free(insn, 1);
cs_close(&handle);
if (no_munmap) {
munmap_virtual_memory((void *)code, self->cpu);
}
return first;
}
disassembler_t* init_disassembler(CPUState *cpu, uint64_t min_addr, uint64_t max_addr, void (*handler)(uint64_t)){
disassembler_t* res = malloc(sizeof(disassembler_t));
res->cpu = cpu;
res->min_addr = min_addr;
res->max_addr = max_addr;
res->handler = handler;
res->debug = false;
res->map = kh_init(ADDR0);
res->list_head = create_list_head();
res->list_element = res->list_head;
return res;
}
void destroy_disassembler(disassembler_t* self){
kh_destroy(ADDR0, self->map);
free_list(self->list_head);
free(self);
}
static inline bool out_of_bounds(disassembler_t* self, uint64_t addr){
return ((addr < self->min_addr) | (addr > self->max_addr));
}
static inline cofi_list* get_obj(disassembler_t* self, uint64_t entry_point, tnt_cache_t* tnt_cache_state){
cofi_list *tmp_obj;
if (!count_tnt(tnt_cache_state))
return NULL;
if (out_of_bounds(self, entry_point)){
return NULL;
}
if(map_get(self, entry_point, (uint64_t *)&tmp_obj)){
tmp_obj = analyse_assembly(self, entry_point, false);
}
if (!tmp_obj || !tmp_obj->cofi_ptr) {
tmp_obj = analyse_assembly(self, entry_point, true);
}
if (!tmp_obj->cofi_ptr) {
printf("Fatal error 1 in get_obj.\n");
asm("int $3\r\n");
}
return tmp_obj;
}
static inline cofi_list* get_cofi_ptr(disassembler_t* self, cofi_list *obj)
{
cofi_list *tmp_obj;
if (!obj->cofi_ptr) {
tmp_obj = analyse_assembly(self, obj->cofi->ins_addr, true);
if (!tmp_obj->cofi_ptr) {
printf("Fatal error 1 in get_cofi_ptr.\n");
asm("int $3\r\n");
}
} else {
tmp_obj = obj->cofi_ptr;
}
return tmp_obj;
}
bool trace_disassembler(disassembler_t* self, uint64_t entry_point, bool isr, tnt_cache_t* tnt_cache_state){
cofi_list *obj, *last_obj;
uint8_t tnt;
obj = get_obj(self, entry_point, tnt_cache_state);
self->handler(entry_point);
while(true){
if(!obj){
if (!count_tnt(tnt_cache_state))
return true;
goto __ret_false;
}
switch(obj->cofi->type){
case COFI_TYPE_CONDITIONAL_BRANCH:
tnt = process_tnt_cache(tnt_cache_state);
switch(tnt){
case TNT_EMPTY:
return true;
case TAKEN:
sample_decoded_detailed("(%d)\t%lx\t(Taken)\n", COFI_TYPE_CONDITIONAL_BRANCH, obj->cofi->ins_addr);
self->handler(obj->cofi->target_addr);
if (out_of_bounds(self, obj->cofi->ins_addr)) {
if (!count_tnt(tnt_cache_state))
return true;
else
goto __ret_false;
}
obj = get_obj(self, obj->cofi->target_addr, tnt_cache_state);
break;
case NOT_TAKEN:
sample_decoded_detailed("(%d)\t%lx\t(Not Taken)\n", COFI_TYPE_CONDITIONAL_BRANCH ,obj->cofi->ins_addr);
//if(!count_tnt())
// return true;
self->handler(obj->cofi->ins_addr + obj->cofi->ins_len);
obj = get_cofi_ptr(self, obj);
break;
}
break;
case COFI_TYPE_UNCONDITIONAL_DIRECT_BRANCH:
sample_decoded_detailed("(%d)\t%lx\n", COFI_TYPE_UNCONDITIONAL_DIRECT_BRANCH ,obj->cofi->ins_addr);
last_obj = obj;
if (out_of_bounds(self, obj->cofi->target_addr)){
if (!count_tnt(tnt_cache_state)){
return true;
} else {
goto __ret_false;
}
//obj = get_cofi_ptr(self, obj);
} else {
obj = get_obj(self, obj->cofi->target_addr, tnt_cache_state);
}
/* loop */
if(obj && (last_obj->cofi->ins_addr == obj->cofi->ins_addr)){
goto __ret_false;
}
break;
case COFI_TYPE_INDIRECT_BRANCH:
self->handler(obj->cofi->target_addr);
sample_decoded_detailed("(2)\t%lx\n",obj->cofi->ins_addr);
if (!count_tnt(tnt_cache_state)){
return true;
} else {
goto __ret_false;
}
obj = get_cofi_ptr(self, obj);
break;
case COFI_TYPE_NEAR_RET:
sample_decoded_detailed("(3)\t%lx\n",obj->cofi->ins_addr);
if (!count_tnt(tnt_cache_state))
return true;
else
goto __ret_false;
obj = get_cofi_ptr(self, obj);
break;
case COFI_TYPE_FAR_TRANSFERS:
sample_decoded_detailed("(4)\t%lx\n",obj->cofi->ins_addr);
if (!count_tnt(tnt_cache_state))
return true;
else
goto __ret_false;
obj = get_cofi_ptr(self, obj);
break;
case NO_COFI_TYPE:
sample_decoded_detailed("(5)\t%lx\n",obj->cofi->ins_addr);
#ifdef DEBUG
#endif
obj = get_cofi_ptr(self, obj);
break;
}
}
__ret_false:
printf("Fatal error 1 in trace_disassembler.\n");
asm("int $3\r\n");
return false;
}