Magisk/core/jni/utils/pattern.c

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#include <malloc.h>
#include <string.h>
#include "utils.h"
static int check_verity_pattern(const char *s) {
int pos = 0;
if (s[0] == ',') ++pos;
if (strncmp(s + pos, "verify", 6) == 0)
pos += 6;
else if (strncmp(s + pos, "avb", 3) == 0)
pos += 3;
else
return -1;
if (s[pos] == '=') {
while (s[pos] != '\0' && s[pos] != ' ' && s[pos] != '\n' && s[pos] != ',') ++pos;
}
return pos;
}
static int check_encryption_pattern(const char *s) {
const char *encrypt_list[] = { "forceencrypt", "forcefdeorfbe", NULL };
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;
}
void patch_init_rc(void **buf, size_t *size) {
int injected = 0;
char *new_data = malloc(*size + 23);
char *old_data = *buf;
size_t pos = 0;
for (char *tok = strsep(&old_data, "\n"); tok; tok = strsep(&old_data, "\n")) {
if (!injected && strncmp(tok, "import", 6) == 0) {
if (strstr(tok, "init.magisk.rc")) {
injected = 1;
} else {
strcpy(new_data + pos, "import /init.magisk.rc\n");
pos += 23;
injected = 1;
}
} else if (strstr(tok, "selinux.reload_policy")) {
continue;
}
// Copy the line
strcpy(new_data + pos, tok);
pos += strlen(tok);
new_data[pos++] = '\n';
}
free(*buf);
*size = pos;
*buf = new_data;
}
int patch_verity(void **buf, uint32_t *size, int patch) {
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int skip, found = 0;
for (int pos = 0; pos < *size; ++pos) {
if ((skip = check_verity_pattern(*buf + pos)) > 0) {
found = 1;
fprintf(stderr, "%s pattern [%.*s]\n", patch ? "Remove" : "Found", skip, (char *) *buf + pos);
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if (patch) {
memcpy(*buf + pos, *buf + pos + skip, *size - pos - skip);
memset(*buf + *size - skip, '\0', skip);
*size -= skip;
} else {
pos += skip - 1;
}
}
}
return found;
}
void patch_encryption(void **buf, uint32_t *size) {
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int skip;
for (int pos = 0; pos < *size; ++pos) {
if ((skip = check_encryption_pattern(*buf + pos)) > 0) {
fprintf(stderr, "Replace pattern [%.*s] with [encryptable]\n", skip, (char *) *buf + pos);
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memcpy(*buf + pos, "encryptable", 11);
memcpy(*buf + pos + 11, *buf + pos + skip, *size - pos - skip);
memset(*buf + *size - skip + 11, '\0', skip - 11);
*size -= (skip - 11);
}
}
}