2021-01-07 07:21:17 +01:00
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#include <libgen.h>
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#include <dlfcn.h>
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#include <sys/mount.h>
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#include <sys/sendfile.h>
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2021-01-07 08:41:37 +01:00
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#include <sys/prctl.h>
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2021-01-07 07:21:17 +01:00
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#include <android/log.h>
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#include <atomic>
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#include <utils.hpp>
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#include "inject.hpp"
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using namespace std;
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static void *self_handle = nullptr;
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static atomic<int> active_threads = -1;
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#define alog(prio) [](auto fmt, auto ap){ \
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return __android_log_vprint(ANDROID_LOG_##prio, "Magisk", fmt, ap); }
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static void inject_logging() {
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log_cb.d = alog(DEBUG);
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log_cb.i = alog(INFO);
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log_cb.w = alog(WARN);
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log_cb.e = alog(ERROR);
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log_cb.ex = nop_ex;
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}
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__attribute__((destructor))
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static void inject_cleanup() {
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if (active_threads < 0)
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return;
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// Setup 1ms
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timespec ts = { .tv_sec = 0, .tv_nsec = 1000000L };
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// Check flag in busy loop
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while (active_threads)
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nanosleep(&ts, nullptr);
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// Wait another 1ms to make sure all threads left our code
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nanosleep(&ts, nullptr);
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}
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2021-01-08 09:53:24 +01:00
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void self_unload() {
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// If unhook failed, do not unload or else it will cause SIGSEGV
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if (!unhook_functions())
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return;
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2021-01-07 07:21:17 +01:00
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new_daemon_thread(reinterpret_cast<void *(*)(void *)>(&dlclose), self_handle);
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active_threads--;
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}
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static void *unload_first_stage(void *) {
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// Setup 1ms
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timespec ts = { .tv_sec = 0, .tv_nsec = 1000000L };
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2021-01-07 08:59:05 +01:00
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while (getenv(INJECT_ENV_1))
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2021-01-07 07:21:17 +01:00
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nanosleep(&ts, nullptr);
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// Wait another 1ms to make sure all threads left our code
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nanosleep(&ts, nullptr);
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unmap_all(INJECT_LIB_1);
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active_threads--;
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return nullptr;
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}
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2021-01-07 08:41:37 +01:00
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// Make sure /proc/self/environ does not reveal our secrets
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// Copy all env to a contiguous memory and set the memory region as MM_ENV
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static void sanitize_environ() {
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static string env;
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for (int i = 0; environ[i]; ++i) {
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2021-01-07 08:59:05 +01:00
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if (str_starts(environ[i], INJECT_ENV_1 "="))
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continue;
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2021-01-07 08:41:37 +01:00
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env += environ[i];
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env += '\0';
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}
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for (int i = 0; i < 2; ++i) {
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bool success = true;
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success &= (0 <= prctl(PR_SET_MM, PR_SET_MM_ENV_START, env.data(), 0, 0));
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success &= (0 <= prctl(PR_SET_MM, PR_SET_MM_ENV_END, env.data() + env.size(), 0, 0));
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if (success)
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break;
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}
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}
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2021-01-07 07:21:17 +01:00
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__attribute__((constructor))
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static void inject_init() {
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inject_logging();
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2021-01-07 08:59:05 +01:00
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if (getenv(INJECT_ENV_2)) {
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2021-01-07 07:21:17 +01:00
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LOGD("zygote: inject 2nd stage\n");
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active_threads = 1;
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2021-01-07 08:59:05 +01:00
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unsetenv(INJECT_ENV_2);
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2021-01-07 07:21:17 +01:00
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// Get our own handle
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self_handle = dlopen(INJECT_LIB_2, RTLD_LAZY);
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dlclose(self_handle);
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2021-01-08 09:53:24 +01:00
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hook_functions();
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2021-01-07 07:21:17 +01:00
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2021-01-07 08:59:05 +01:00
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// Some cleanup
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2021-01-07 08:41:37 +01:00
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sanitize_environ();
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2021-01-07 08:59:05 +01:00
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active_threads++;
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new_daemon_thread(&unload_first_stage);
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} else if (char *env = getenv(INJECT_ENV_1)) {
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LOGD("zygote: inject 1st stage\n");
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if (env[0] == '1')
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unsetenv("LD_PRELOAD");
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else
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setenv("LD_PRELOAD", env, 1); // Restore original LD_PRELOAD
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// Setup second stage
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setenv(INJECT_ENV_2, "1", 1);
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cp_afc(INJECT_LIB_1, INJECT_LIB_2);
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dlopen(INJECT_LIB_2, RTLD_LAZY);
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unsetenv(INJECT_ENV_1);
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2021-01-07 07:21:17 +01:00
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}
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}
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int app_process_main(int argc, char *argv[]) {
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inject_logging();
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char buf[4096];
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if (realpath("/proc/self/exe", buf) == nullptr)
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return 1;
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int in = xopen(buf, O_RDONLY);
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int out = xopen(INJECT_LIB_1, O_CREAT | O_WRONLY | O_TRUNC, 0777);
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sendfile(out, in, nullptr, INT_MAX);
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close(in);
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close(out);
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if (char *ld = getenv("LD_PRELOAD")) {
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char env[128];
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sprintf(env, "%s:" INJECT_LIB_1, ld);
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setenv("LD_PRELOAD", env, 1);
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setenv(INJECT_ENV_1, ld, 1); // Backup original LD_PRELOAD
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} else {
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setenv("LD_PRELOAD", INJECT_LIB_1, 1);
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setenv(INJECT_ENV_1, "1", 1);
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}
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// Execute real app_process
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xumount2(buf, MNT_DETACH);
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execve(buf, argv, environ);
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2021-01-07 08:41:37 +01:00
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return 1;
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2021-01-07 07:21:17 +01:00
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}
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