nganhkhoa/ios-kernel-patch
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minimization

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This commit is contained in:
comex 2011-03-15 16:15:01 -04:00
parent 4ffc4686e7
commit 940246cacc
1 changed files with 0 additions and 124 deletions
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124
dmini.c
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@ -25,122 +25,6 @@ static int position_of_nth_one(uint32_t number, int n) {
}
// similar to below, but no alignment restriction
// must include r0, lr, and pc, but not r7
void find_second_ldm(struct binary *binary, uint32_t valid_conds, int reg, addr_t *addrp, int *num_before_r0, int *num_after_r0) {
//printf("reg=%d\n", reg);
range_t range;
for(int i = 0; (range = b_nth_segment(binary, i)).binary; i++) {
if(!(binary->dyld_mappings[i].sfm_init_prot & PROT_EXEC)) continue;
uint32_t *p = rangeconv(range).start;
for(addr_t addr = range.start; addr + 4 <= range.start + range.size; p++, addr += 4) {
uint32_t val = *p;
uint32_t cond = ((val & 0xf0000000) >> 28);
if(cond == 15 || (1u << (2*cond)) != (valid_conds & (3 << (2*cond)))) {
continue;
}
int offset;
if((val & 0xfd0c081) == 0x890c001) {
offset = 0;
} else if((val & 0xfd0c081) == 0x990c001) {
offset = 1;
} else {
continue;
}
uint32_t rn = (val & 0xf0000) >> 16;
if((int) rn != reg) {
continue;
}
*addrp = addr;
*num_before_r0 = offset;
*num_after_r0 = count_ones(val & 0x3f7e);
return;
}
}
die("didn't find second ldm /anywhere/");
}
// ldmi[ab]<cond> r[05]!?, ...
// - aligned to 0x1000
// - includes pc, but not r7
// - PC is at position 3-5
// each set of two bits in valid_conds is:
// 0 - known false
// 1 - known true
// 2 - unknown
void find_kernel_ldm(struct binary *binary, uint32_t valid_conds, addr_t *addrp, uint32_t *condsp, int *regp) {
range_t range;
uint32_t my_valid_conds = valid_conds;
for(int i = 0; (range = b_nth_segment(binary, i)).binary; i++) {
if(!(binary->dyld_mappings[i].sfm_init_prot & PROT_EXEC)) continue;
char *p = rangeconv(range).start;
addr_t addr = (range.start + 0xfff) & ~0xfff;
while(addr + 4 <= range.start + range.size) {
if((addr & 0xfff) == 0) {
my_valid_conds = valid_conds;
}
uint32_t val = *((uint32_t *) (p + addr - range.start));
uint32_t cond = ((val & 0xf0000000) >> 28);
if(cond != 15 && 0 == (my_valid_conds & (3 << (2*cond)))) {
goto harmless;
} else if(cond != 15 && !(val & 0xc000000) && (val & 0xe100000) != 0xc100000) { // data processing, but not LDC
uint32_t rd = (val & 0xf000) >> 12;
if(rd != 0 && rd != 13 && rd != 15) {
if(!(val & (1 << 20))) my_valid_conds = 0x1aaaaaaa; // AL known 1, others unknown
goto harmless;
} else if(rd == 0) {
uint32_t op = ((val & 0x1f00000) >> 20);
if(op == 17 || op == 19 || op == 21 || op == 23) {
my_valid_conds = 0x1aaaaaaa;
goto harmless;
}
}
}
if(cond == 15 || (1u << (2*cond)) != (my_valid_conds & (3 << (2*cond)))) {
goto nope;
}
// 0xfdf to be strict about user registers, 0xf9f otherwise
int offset;
if((val & 0xfd08080) == 0x8908000) {
// ldmia
offset = 0;
} else if((val & 0xfd08080) == 0x9908000) {
// ldmib
offset = 1;
} else {
goto nope;
}
uint32_t rn = (val & 0xf0000) >> 16;
uint32_t reglist = val & 0x7f7f;
int ones = count_ones(reglist) + offset; // ones = offset of PC
//printf("addr=%x rn=%u ones=%d val=%x\n", addr, rn, ones, val);
if(rn != 0 && rn != 5) goto nope;
//printf("rn=%u ones=%d\n", rn, ones);
if(ones < 3 || ones > 5) goto nope;
*addrp = addr;
*condsp = my_valid_conds;
*regp = position_of_nth_one(reglist, 2);
return;
nope: /*printf("%08x nope\n", addr);*/ addr = (addr + 0x1000) & ~0xfff; continue;
harmless: /*printf("%08x harmless\n", addr);*/ addr += 4; continue;
}
}
die("didn't find ldm /anywhere/");
}
void main_loop() {
@ -165,14 +49,6 @@ void main_loop() {
} else if(mode == 3) {
b_dyldcache_load_macho(&binary, arg);
result = 0;
} else if(mode == 4) {
addr_t first, second; int reg, num_before_r0, num_after_r0;
uint32_t conds = (uint32_t) strtoll(arg, NULL, 16);
find_kernel_ldm(&binary, conds, &first, &conds, &reg);
find_second_ldm(&binary, conds, reg, &second, &num_before_r0, &num_after_r0);
printf("+ %x %x %x %x\n", first, second, num_before_r0, num_after_r0);
fflush(stdout);
continue;
} else die("mode?");
printf("+ %x\n", result);