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asmhlp.cpp
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asmhlp.cpp
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#include <sstream>
#include <keystone/keystone.h>
#include "asmhlp.hpp"
#include "dishlp.hpp"
#include "utils.hpp"
int valid_for_replace_long(x86_reg reg) {
switch(reg) {
case X86_REG_EAX:
case X86_REG_EBX:
case X86_REG_ECX:
case X86_REG_EDX:
return 1;
default:
return 0;
}
}
asmhlp::asmhlp() {
ks_open(KS_ARCH_X86, KS_MODE_LITTLE_ENDIAN | KS_MODE_32, &eng);
}
asmhlp::~asmhlp() {
ks_close(eng);
}
void asmhlp::set_mem (std::shared_ptr<memhlp> mem) {
this->mem = mem;
}
int asmhlp::replace(cs_insn *i, cs_insn *nxt, enum symbl sym) {
std::stringstream str;
int valid = 1;
uint8_t *enc;
cs_insn *tar = i;
cs_insn *nop = NULL;
size_t size;
size_t stat_cnt;
if (nxt && OP(nxt, 1).type == X86_OP_MEM &&
OP(nxt, 1).mem.disp == 0 &&
OP(nxt, 1).mem.base == OP(i, 0).reg &&
OP(nxt, 1).mem.index != X86_REG_INVALID)
valid = 2;
str << std::hex;
switch (sym) {
case SYM_BOOL_AND:
case SYM_ALU_AND:
if (valid == 1) return 0;
str << "mov " << get_name(get_32bit(OP(nxt, 0).reg)) << ", ";
if (OP(i, 1).mem.base != X86_REG_INVALID)
str << get_name(OP(i, 1).mem.base);
else
str << get_name(OP(i, 1).mem.index);
str << "; and " << get_name(get_32bit(OP(nxt, 0).reg));
str << ", " << get_name(OP(nxt, 1).mem.index);
nop = nxt;
break;
case SYM_BOOL_OR:
case SYM_ALU_OR:
if (valid == 1) return 0;
str << "mov " << get_name(get_32bit(OP(nxt, 0).reg)) << ", ";
if (OP(i, 1).mem.base != X86_REG_INVALID)
str << get_name(OP(i, 1).mem.base);
else
str << get_name(OP(i, 1).mem.index);
str << "; or " << get_name(get_32bit(OP(nxt, 0).reg));
str << ", " << get_name(OP(nxt, 1).mem.index);
nop = nxt;
break;
case SYM_BOOL_XOR:
case SYM_ALU_XOR:
if (valid == 1) return 0;
str << "mov " << get_name(get_32bit(OP(nxt, 0).reg)) << ", ";
if (OP(i, 1).mem.base != X86_REG_INVALID)
str << get_name(OP(i, 1).mem.base);
else
str << get_name(OP(i, 1).mem.index);
str << "; xor " << get_name(get_32bit(OP(nxt, 0).reg));
str << ", " << get_name(OP(nxt, 1).mem.index);
nop = nxt;
break;
case SYM_STP_ADD4:
str << "lea " << get_name(OP(i, 0).reg) << ", [";
if (OP(i, 1).mem.base != X86_REG_INVALID)
str << get_name(OP(i, 1).mem.base);
else
str << get_name(OP(i, 1).mem.index);
str << " + 4]";
break;
case SYM_STP_SUB4:
str << "lea " << get_name(OP(i, 0).reg) << ", [";
if (OP(i, 1).mem.base != X86_REG_INVALID)
str << get_name(OP(i, 1).mem.base);
else
str << get_name(OP(i, 1).mem.index);
str << " - 4]";
break;
case SYM_ALU_INV8:
case SYM_ALU_INV16:
nxt = NULL;
if (OP(i, 1).mem.base != X86_REG_INVALID &&
OP(i, 1).mem.index != X86_REG_INVALID) {
str << "lea " << get_name(get_32bit(OP(nxt, 0).reg));
str << ", [" << get_name(OP(i, 1).mem.base);
str << " + " << get_name(OP(i, 1).mem.index);
str << "]; ";
} else if (OP(i, 1).mem.base != X86_REG_INVALID) {
str << "mov " << get_name(get_32bit(OP(i, 0).reg));
str << ", " << get_name(OP(i, 1).mem.base) << "; ";
} else {
str << "mov " << get_name(get_32bit(OP(i, 0).reg));
str << ", " << get_name(OP(i, 1).mem.index) << "; ";
}
str << "not " << get_name(OP(i, 0).reg);
break;
case SYM_ALU_B7:
nxt = NULL;
if (OP(i, 1).mem.base != X86_REG_INVALID &&
OP(i, 1).mem.index != X86_REG_INVALID) {
str << "lea " << get_name(get_32bit(OP(nxt, 0).reg));
str << ", [" << get_name(OP(i, 1).mem.base);
str << " + " << get_name(OP(i, 1).mem.index);
str << "]; ";
} else if (OP(i, 1).mem.base != X86_REG_INVALID) {
str << "mov " << get_name(get_32bit(OP(i, 0).reg));
str << ", " << get_name(OP(i, 1).mem.base) << "; ";
} else {
str << "mov " << get_name(get_32bit(OP(i, 0).reg));
str << ", " << get_name(OP(i, 1).mem.index) << "; ";
}
str << "shr " << get_name(OP(i, 0).reg) << ", 7";
break;
case SYM_ALU_ADD:
if (valid == 1) return 0;
str << "lea " << get_name(get_32bit(OP(nxt, 0).reg));
str << ", [" << get_name(OP(i, 1).mem.index);
str << " + " << get_name(OP(nxt, 1).mem.index);
str << "]";
tar = nxt;
nop = i;
break;
case SYM_ON:
str << "mov " << get_name(OP(i, 0).reg) << ", 1";
break;
case SYM_FAULT:
if (!(is_reg_mem(&OP(nxt, 0), X86_REG_INVALID) &&
OP(nxt, 0).mem.base == OP(i, 0).reg) &&
!(is_reg_mem(&OP(nxt, 1), X86_REG_INVALID) &&
OP(nxt, 1).mem.base == OP(i, 0).reg))
return 0;
if (pc)
str << "call 0x";
else
str << "jmp 0x";
str << mem->get_sym_addr(SYM_DISPATCH);
nop = nxt;
break;
default:
return 0;
}
/*if (sym == SYM_ALU_ADD) {
std::cout << "REPLACE: " << std::endl;
std::cout << i->mnemonic << " " << i->op_str << std::endl;
if (nxt)
std::cout << nxt->mnemonic << " " << nxt->op_str << std::endl;
std::cout << str.str() << std::endl;
}*/
if (ks_asm(eng, str.str().c_str(), tar->address, &enc, &size, &stat_cnt)) return 0;
if (tar->size >= size) {
memcpy(mem->get_ptr(tar->address), enc, size);
memset(mem->get_ptr(tar->address) + size, 0x90, tar->size - size);
}
if (nop)
memset(mem->get_ptr(nop->address), 0x90, nop->size);
ks_free(enc);
return size;
}
void asmhlp::set_patch_call(bool b) {
pc = b;
}