Magisk/native/jni/magiskboot/pattern.cpp

71 lines
1.7 KiB
C++

#include <malloc.h>
#include <string.h>
#include <utils.h>
#include "magiskboot.h"
static int check_verity_pattern(const char *s) {
int skip = 0;
if (s[0] == ',') ++skip;
if (strncmp(s + skip, "verify", 6) == 0)
skip += 6;
else if (strncmp(s + skip, "avb", 3) == 0)
skip += 3;
else
return -1;
if (s[skip] == '=') {
while (s[skip] != '\0' && s[skip] != ' ' && s[skip] != '\n' && s[skip] != ',') ++skip;
}
return skip;
}
static int check_encryption_pattern(const char *s) {
const char *encrypt_list[] = { "forceencrypt", "forcefdeorfbe", nullptr };
for (int i = 0 ; encrypt_list[i]; ++i) {
int len = strlen(encrypt_list[i]);
if (strncmp(s, encrypt_list[i], len) == 0)
return len;
}
return -1;
}
char *patch_verity(const void *buf, uint32_t &size) {
auto src = static_cast<const char *>(buf);
int src_size = size;
bool found = false;
char patched[4096];
int write = 0;
for (int read = 0; read < src_size; ++read, ++write) {
if (int skip; (skip = check_verity_pattern(src + read)) > 0) {
fprintf(stderr, "Found pattern [%.*s]\n", skip, src + read);
size -= skip;
read += skip;
found = true;
}
patched[write] = src[read];
}
patched[write] = '\0';
return found ? strdup(patched) : nullptr;
}
void patch_encryption(void **buf, uint32_t *size) {
int skip, src_size = *size;
char *src = (char *) *buf, *patched = (char *) xcalloc(src_size, 1);
for (int read = 0, write = 0; read < src_size; ++read, ++write) {
if ((skip = check_encryption_pattern(src + read)) > 0) {
fprintf(stderr, "Replace pattern [%.*s] with [encryptable]\n", skip, src + read);
memcpy(patched + read, "encryptable", 11);
read += skip;
write += 11;
*size -= (skip - 11);
}
patched[write] = src[read];
}
free(*buf);
*buf = patched;
}