mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-12-01 05:55:26 +00:00
428 lines
12 KiB
C++
428 lines
12 KiB
C++
#include <libgen.h>
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#include <dlfcn.h>
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#include <sys/prctl.h>
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#include <android/log.h>
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#include <utils.hpp>
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#include <daemon.hpp>
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#include <magisk.hpp>
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#include <db.hpp>
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#include "zygisk.hpp"
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#include "module.hpp"
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#include "deny/deny.hpp"
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using namespace std;
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void *self_handle = nullptr;
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static int zygisk_log(int prio, const char *fmt, va_list ap);
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#define zlog(prio) [](auto fmt, auto ap){ return zygisk_log(ANDROID_LOG_##prio, fmt, ap); }
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static void zygisk_logging() {
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log_cb.d = zlog(DEBUG);
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log_cb.i = zlog(INFO);
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log_cb.w = zlog(WARN);
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log_cb.e = zlog(ERROR);
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log_cb.ex = nop_ex;
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}
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static char *first_stage_path = nullptr;
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void unload_first_stage() {
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if (first_stage_path) {
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unmap_all(first_stage_path);
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free(first_stage_path);
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first_stage_path = nullptr;
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}
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}
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// Make sure /proc/self/environ is sanitized
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// Filter env and reset MM_ENV_END
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static void sanitize_environ() {
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char *cur = environ[0];
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for (int i = 0; environ[i]; ++i) {
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// Copy all env onto the original stack
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int len = strlen(environ[i]);
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memmove(cur, environ[i], len + 1);
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environ[i] = cur;
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cur += len + 1;
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}
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prctl(PR_SET_MM, PR_SET_MM_ENV_END, cur, 0, 0);
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}
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__attribute__((destructor))
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static void zygisk_cleanup_wait() {
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if (self_handle) {
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// Wait 10us to make sure none of our code is executing
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timespec ts = { .tv_sec = 0, .tv_nsec = 10000L };
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nanosleep(&ts, nullptr);
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}
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}
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#define SECOND_STAGE_PTR "ZYGISK_PTR"
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static void second_stage_entry(void *handle, const char *tmp, char *path) {
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self_handle = handle;
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MAGISKTMP = tmp;
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unsetenv(INJECT_ENV_2);
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unsetenv(SECOND_STAGE_PTR);
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zygisk_logging();
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ZLOGD("inject 2nd stage\n");
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hook_functions();
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// First stage will be unloaded before the first fork
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first_stage_path = path;
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}
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static void first_stage_entry() {
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android_logging();
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ZLOGD("inject 1st stage\n");
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char *ld = getenv("LD_PRELOAD");
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char tmp[128];
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strlcpy(tmp, getenv("MAGISKTMP"), sizeof(tmp));
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char *path;
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if (char *c = strrchr(ld, ':')) {
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*c = '\0';
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setenv("LD_PRELOAD", ld, 1); // Restore original LD_PRELOAD
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path = strdup(c + 1);
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} else {
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unsetenv("LD_PRELOAD");
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path = strdup(ld);
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}
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unsetenv(INJECT_ENV_1);
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unsetenv("MAGISKTMP");
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sanitize_environ();
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char *num = strrchr(path, '.') - 1;
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// Update path to 2nd stage lib
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*num = '2';
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// Load second stage
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setenv(INJECT_ENV_2, "1", 1);
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void *handle = dlopen(path, RTLD_LAZY);
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remap_all(path);
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// Revert path to 1st stage lib
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*num = '1';
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// Run second stage entry
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char *env = getenv(SECOND_STAGE_PTR);
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decltype(&second_stage_entry) second_stage;
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sscanf(env, "%p", &second_stage);
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second_stage(handle, tmp, path);
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}
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__attribute__((constructor))
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static void zygisk_init() {
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if (getenv(INJECT_ENV_2)) {
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// Return function pointer to first stage
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char buf[128];
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snprintf(buf, sizeof(buf), "%p", &second_stage_entry);
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setenv(SECOND_STAGE_PTR, buf, 1);
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} else if (getenv(INJECT_ENV_1)) {
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first_stage_entry();
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}
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}
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// The following code runs in zygote/app process
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static int zygisk_log(int prio, const char *fmt, va_list ap) {
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// If we don't have log pipe set, ask magiskd for it
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// This could happen multiple times in zygote because it was closed to prevent crashing
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if (logd_fd < 0) {
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// Change logging temporarily to prevent infinite recursion and stack overflow
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android_logging();
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if (int fd = connect_daemon(); fd >= 0) {
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write_int(fd, ZYGISK_REQUEST);
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write_int(fd, ZYGISK_GET_LOG_PIPE);
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if (read_int(fd) == 0) {
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logd_fd = recv_fd(fd);
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}
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close(fd);
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}
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zygisk_logging();
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}
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sigset_t mask;
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sigset_t orig_mask;
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bool sig = false;
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// Make sure SIGPIPE won't crash zygote
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if (logd_fd >= 0) {
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sig = true;
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sigemptyset(&mask);
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sigaddset(&mask, SIGPIPE);
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pthread_sigmask(SIG_BLOCK, &mask, &orig_mask);
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}
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int ret = magisk_log(prio, fmt, ap);
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if (sig) {
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timespec ts{};
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sigtimedwait(&mask, nullptr, &ts);
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pthread_sigmask(SIG_SETMASK, &orig_mask, nullptr);
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}
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return ret;
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}
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int remote_get_info(int uid, const char *process, uint32_t *flags, vector<int> &fds) {
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if (int fd = connect_daemon(); fd >= 0) {
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write_int(fd, ZYGISK_REQUEST);
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write_int(fd, ZYGISK_GET_INFO);
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write_int(fd, uid);
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write_string(fd, process);
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xxread(fd, flags, sizeof(*flags));
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if ((*flags & UNMOUNT_MASK) != UNMOUNT_MASK) {
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fds = recv_fds(fd);
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}
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return fd;
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}
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return -1;
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}
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// The following code runs in magiskd
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static vector<int> get_module_fds(bool is_64_bit) {
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vector<int> fds;
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// All fds passed to send_fds have to be valid file descriptors.
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// To workaround this issue, send over STDOUT_FILENO as an indicator of an
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// invalid fd as it will always be /dev/null in magiskd
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if (is_64_bit) {
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#if defined(__LP64__)
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std::transform(module_list->begin(), module_list->end(), std::back_inserter(fds),
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[](const module_info &info) { return info.z64 < 0 ? STDOUT_FILENO : info.z64; });
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#endif
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} else {
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std::transform(module_list->begin(), module_list->end(), std::back_inserter(fds),
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[](const module_info &info) { return info.z32 < 0 ? STDOUT_FILENO : info.z32; });
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}
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return fds;
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}
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static bool get_exe(int pid, char *buf, size_t sz) {
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snprintf(buf, sz, "/proc/%d/exe", pid);
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return xreadlink(buf, buf, sz) > 0;
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}
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static pthread_mutex_t zygiskd_lock = PTHREAD_MUTEX_INITIALIZER;
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static int zygiskd_sockets[] = { -1, -1 };
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#define zygiskd_socket zygiskd_sockets[is_64_bit]
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static void connect_companion(int client, bool is_64_bit) {
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mutex_guard g(zygiskd_lock);
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if (zygiskd_socket >= 0) {
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// Make sure the socket is still valid
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pollfd pfd = { zygiskd_socket, 0, 0 };
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poll(&pfd, 1, 0);
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if (pfd.revents) {
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// Any revent means error
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close(zygiskd_socket);
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zygiskd_socket = -1;
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}
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}
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if (zygiskd_socket < 0) {
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int fds[2];
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socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, fds);
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zygiskd_socket = fds[0];
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if (fork_dont_care() == 0) {
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string exe = MAGISKTMP + "/magisk" + (is_64_bit ? "64" : "32");
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// This fd has to survive exec
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fcntl(fds[1], F_SETFD, 0);
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char buf[16];
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snprintf(buf, sizeof(buf), "%d", fds[1]);
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execl(exe.data(), "zygisk", "companion", buf, (char *) nullptr);
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exit(-1);
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}
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close(fds[1]);
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vector<int> module_fds = get_module_fds(is_64_bit);
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send_fds(zygiskd_socket, module_fds.data(), module_fds.size());
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// Wait for ack
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if (read_int(zygiskd_socket) != 0) {
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LOGE("zygiskd startup error\n");
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return;
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}
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}
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send_fd(zygiskd_socket, client);
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}
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static timespec last_zygote_start;
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static int zygote_start_counts[] = { 0, 0 };
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#define zygote_start_count zygote_start_counts[is_64_bit]
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#define zygote_started (zygote_start_counts[0] + zygote_start_counts[1])
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#define zygote_start_reset(val) { zygote_start_counts[0] = val; zygote_start_counts[1] = val; }
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static void setup_files(int client, const sock_cred *cred) {
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LOGD("zygisk: setup files for pid=[%d]\n", cred->pid);
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char buf[256];
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if (!get_exe(cred->pid, buf, sizeof(buf))) {
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write_int(client, 1);
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return;
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}
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bool is_64_bit = str_ends(buf, "64");
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if (!zygote_started) {
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// First zygote launch, record time
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clock_gettime(CLOCK_MONOTONIC, &last_zygote_start);
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}
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if (zygote_start_count) {
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// This zygote ABI had started before, kill existing zygiskd
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close(zygiskd_sockets[0]);
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close(zygiskd_sockets[1]);
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zygiskd_sockets[0] = -1;
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zygiskd_sockets[1] = -1;
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}
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++zygote_start_count;
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if (zygote_start_count >= 5) {
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// Bootloop prevention
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timespec ts;
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clock_gettime(CLOCK_MONOTONIC, &ts);
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if (ts.tv_sec - last_zygote_start.tv_sec > 60) {
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// This is very likely manual soft reboot
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memcpy(&last_zygote_start, &ts, sizeof(ts));
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zygote_start_reset(1);
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} else {
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// If any zygote relaunched more than 5 times within a minute,
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// don't do any setups further to prevent bootloop.
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zygote_start_reset(999);
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write_int(client, 1);
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return;
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}
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}
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write_int(client, 0);
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send_fd(client, is_64_bit ? app_process_64 : app_process_32);
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string path = MAGISKTMP + "/" ZYGISKBIN "/zygisk." + basename(buf);
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cp_afc(buf, (path + ".1.so").data());
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cp_afc(buf, (path + ".2.so").data());
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write_string(client, MAGISKTMP);
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}
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static void magiskd_passthrough(int client) {
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bool is_64_bit = read_int(client);
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write_int(client, 0);
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send_fd(client, is_64_bit ? app_process_64 : app_process_32);
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}
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atomic<int> cached_manager_app_id = -1;
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extern bool uid_granted_root(int uid);
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static void get_process_info(int client, const sock_cred *cred) {
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int uid = read_int(client);
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string process = read_string(client);
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uint32_t flags = 0;
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// This function is called on every single zygote process specialization,
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// so performance is critical. get_manager_app_id() is expensive as it goes
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// through a SQLite query and potentially multiple filesystem stats, so we
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// really want to cache the app ID value. inotify will invalidate the app ID
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// cache for us.
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if (uid != 1000) {
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int manager_app_id = cached_manager_app_id;
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if (manager_app_id < 0) {
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manager_app_id = get_manager_app_id();
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cached_manager_app_id = manager_app_id;
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}
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if (to_app_id(uid) == manager_app_id) {
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flags |= PROCESS_IS_MAGISK_APP;
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}
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if (denylist_enforced) {
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flags |= DENYLIST_ENFORCING;
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}
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if (is_deny_target(uid, process)) {
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flags |= PROCESS_ON_DENYLIST;
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}
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if (uid_granted_root(uid)) {
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flags |= PROCESS_GRANTED_ROOT;
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}
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}
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xwrite(client, &flags, sizeof(flags));
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if ((flags & UNMOUNT_MASK) != UNMOUNT_MASK) {
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char buf[256];
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get_exe(cred->pid, buf, sizeof(buf));
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vector<int> fds = get_module_fds(str_ends(buf, "64"));
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send_fds(client, fds.data(), fds.size());
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}
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// The following will only happen for system_server
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int slots = read_int(client);
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int id = 0;
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for (int i = 0; i < slots; ++i) {
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dynamic_bitset::slot_type l = 0;
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xxread(client, &l, sizeof(l));
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dynamic_bitset::slot_bits bits(l);
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for (int j = 0; id < module_list->size(); ++j, ++id) {
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if (!bits[j]) {
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// Either not a zygisk module, or incompatible
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char buf[4096];
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snprintf(buf, sizeof(buf), MODULEROOT "/%s/zygisk",
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module_list->operator[](id).name.data());
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if (int dirfd = open(buf, O_RDONLY | O_CLOEXEC); dirfd >= 0) {
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close(xopenat(dirfd, "unloaded", O_CREAT | O_RDONLY, 0644));
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close(dirfd);
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}
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}
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}
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}
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}
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static void send_log_pipe(int fd) {
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// There is race condition here, but we can't really do much about it...
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if (logd_fd >= 0) {
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write_int(fd, 0);
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send_fd(fd, logd_fd);
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} else {
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write_int(fd, 1);
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}
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}
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static void get_moddir(int client) {
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int id = read_int(client);
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char buf[4096];
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snprintf(buf, sizeof(buf), MODULEROOT "/%s", module_list->operator[](id).name.data());
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int dfd = xopen(buf, O_RDONLY | O_CLOEXEC);
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send_fd(client, dfd);
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close(dfd);
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}
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void zygisk_handler(int client, const sock_cred *cred) {
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int code = read_int(client);
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char buf[256];
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switch (code) {
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case ZYGISK_SETUP:
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setup_files(client, cred);
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break;
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case ZYGISK_PASSTHROUGH:
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magiskd_passthrough(client);
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break;
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case ZYGISK_GET_INFO:
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get_process_info(client, cred);
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break;
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case ZYGISK_GET_LOG_PIPE:
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send_log_pipe(client);
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break;
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case ZYGISK_CONNECT_COMPANION:
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get_exe(cred->pid, buf, sizeof(buf));
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connect_companion(client, str_ends(buf, "64"));
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break;
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case ZYGISK_GET_MODDIR:
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get_moddir(client);
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break;
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}
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close(client);
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}
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