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Zygisk code refactor

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topjohnwu 2022-09-07 13:48:20 -07:00
parent 4e14dab60a
commit ccf21b0992
1 changed files with 82 additions and 90 deletions
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166
native/src/zygisk/hook.cpp
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@ -62,12 +62,11 @@ struct HookContext {
HookContext() : env(nullptr), args{nullptr}, process(nullptr), pid(-1), info_flags(0) {} HookContext() : env(nullptr), args{nullptr}, process(nullptr), pid(-1), info_flags(0) {}
void setup_fd_ignore();
void sanitize_fds(); void sanitize_fds();
void run_modules_pre(const vector<int> &fds); void run_modules_pre(const vector<int> &fds);
void run_modules_post(); void run_modules_post();
DCL_PRE_POST(fork) DCL_PRE_POST(fork)
DCL_PRE_POST(app_specialize)
DCL_PRE_POST(nativeForkAndSpecialize) DCL_PRE_POST(nativeForkAndSpecialize)
DCL_PRE_POST(nativeSpecializeAppProcess) DCL_PRE_POST(nativeSpecializeAppProcess)
DCL_PRE_POST(nativeForkSystemServer) DCL_PRE_POST(nativeForkSystemServer)
@ -389,15 +388,42 @@ uint32_t ZygiskModule::getFlags() {
// ----------------------------------------------------------------- // -----------------------------------------------------------------
void HookContext::setup_fd_ignore() { int sigmask(int how, int signum) {
sigset_t set;
sigemptyset(&set);
sigaddset(&set, signum);
return sigprocmask(how, &set, nullptr);
}
void HookContext::fork_pre() {
g_ctx = this;
// Do our own fork before loading any 3rd party code
// First block SIGCHLD, unblock after original fork is done
sigmask(SIG_BLOCK, SIGCHLD);
pid = old_fork();
if (pid != 0)
return;
// Record all open fds
auto dir = xopen_dir("/proc/self/fd");
for (dirent *entry; (entry = xreaddir(dir.get()));) {
int fd = parse_int(entry->d_name);
if (fd < 0 || fd >= MAX_FD_SIZE) {
close(fd);
continue;
}
allowed_fds[fd] = true;
}
// The dirfd should not be allowed
allowed_fds[dirfd(dir.get())] = false;
}
void HookContext::sanitize_fds() {
if (flags[APP_FORK_AND_SPECIALIZE]) { if (flags[APP_FORK_AND_SPECIALIZE]) {
if (args.app->fds_to_ignore == nullptr) { if (args.app->fds_to_ignore == nullptr) {
// The field fds_to_ignore don't exist before Android 8.0, which FDs are not checked // The field fds_to_ignore don't exist before Android 8.0, which FDs are not checked
flags[SKIP_CLOSE_LOGD_FD] = true; flags[SKIP_CLOSE_LOGD_FD] = true;
return; } else if (jintArray fdsToIgnore = *args.app->fds_to_ignore) {
}
bool success = false;
if (jintArray fdsToIgnore = *args.app->fds_to_ignore) {
int *arr = env->GetIntArrayElements(fdsToIgnore, nullptr); int *arr = env->GetIntArrayElements(fdsToIgnore, nullptr);
int len = env->GetArrayLength(fdsToIgnore); int len = env->GetArrayLength(fdsToIgnore);
for (int i = 0; i < len; ++i) { for (int i = 0; i < len; ++i) {
@ -413,7 +439,7 @@ void HookContext::setup_fd_ignore() {
int fd = logd_fd; int fd = logd_fd;
env->SetIntArrayRegion(newFdList, len, 1, &fd); env->SetIntArrayRegion(newFdList, len, 1, &fd);
*args.app->fds_to_ignore = newFdList; *args.app->fds_to_ignore = newFdList;
success = true; flags[SKIP_CLOSE_LOGD_FD] = true;
} }
env->ReleaseIntArrayElements(fdsToIgnore, arr, JNI_ABORT); env->ReleaseIntArrayElements(fdsToIgnore, arr, JNI_ABORT);
} else { } else {
@ -422,19 +448,16 @@ void HookContext::setup_fd_ignore() {
int fd = logd_fd; int fd = logd_fd;
env->SetIntArrayRegion(newFdList, 0, 1, &fd); env->SetIntArrayRegion(newFdList, 0, 1, &fd);
*args.app->fds_to_ignore = newFdList; *args.app->fds_to_ignore = newFdList;
success = true; flags[SKIP_CLOSE_LOGD_FD] = true;
} }
} }
flags[SKIP_CLOSE_LOGD_FD] = success;
}
} }
void HookContext::sanitize_fds() { if (pid != 0)
setup_fd_ignore(); return;
// Close all forbidden fds to prevent crashing // Close all forbidden fds to prevent crashing
auto dir = xopen_dir("/proc/self/fd"); auto dir = xopen_dir("/proc/self/fd");
rewinddir(dir.get());
int dfd = dirfd(dir.get()); int dfd = dirfd(dir.get());
for (dirent *entry; (entry = xreaddir(dir.get()));) { for (dirent *entry; (entry = xreaddir(dir.get()));) {
int fd = parse_int(entry->d_name); int fd = parse_int(entry->d_name);
@ -444,36 +467,6 @@ void HookContext::sanitize_fds() {
} }
} }
int sigmask(int how, int signum) {
sigset_t set;
sigemptyset(&set);
sigaddset(&set, signum);
return sigprocmask(how, &set, nullptr);
}
void HookContext::fork_pre() {
g_ctx = this;
// Do our own fork before loading any 3rd party code
// First block SIGCHLD, unblock after original fork is done
sigmask(SIG_BLOCK, SIGCHLD);
pid = old_fork();
if (pid == 0) {
// Record all open fds
auto dir = xopen_dir("/proc/self/fd");
for (dirent *entry; (entry = xreaddir(dir.get()));) {
int fd = parse_int(entry->d_name);
if (fd < 0 || fd >= MAX_FD_SIZE) {
close(fd);
continue;
}
allowed_fds[fd] = true;
}
// The dirfd should not be allowed
allowed_fds[dirfd(dir.get())] = false;
}
}
void HookContext::fork_post() { void HookContext::fork_post() {
// Unblock SIGCHLD in case the original method didn't // Unblock SIGCHLD in case the original method didn't
sigmask(SIG_UNBLOCK, SIGCHLD); sigmask(SIG_UNBLOCK, SIGCHLD);
@ -527,6 +520,34 @@ void HookContext::run_modules_post() {
} }
} }
void HookContext::app_specialize_pre() {
flags[APP_SPECIALIZE] = true;
vector<int> module_fds;
int fd = remote_get_info(args.app->uid, process, &info_flags, module_fds);
if ((info_flags & UNMOUNT_MASK) == UNMOUNT_MASK) {
ZLOGI("[%s] is on the denylist\n", process);
flags[DO_REVERT_UNMOUNT] = true;
} else if (fd >= 0) {
run_modules_pre(module_fds);
}
close(fd);
}
void HookContext::app_specialize_post() {
run_modules_post();
if (info_flags & PROCESS_IS_MAGISK_APP) {
setenv("ZYGISK_ENABLED", "1", 1);
}
// Cleanups
env->ReleaseStringUTFChars(args.app->nice_name, process);
g_ctx = nullptr;
close(logd_fd.exchange(-1));
android_logging();
}
void HookContext::unload_zygisk() { void HookContext::unload_zygisk() {
if (flags[CAN_UNLOAD_ZYGISK]) { if (flags[CAN_UNLOAD_ZYGISK]) {
// Do NOT call the destructor // Do NOT call the destructor
@ -547,57 +568,27 @@ void HookContext::unload_zygisk() {
void HookContext::nativeSpecializeAppProcess_pre() { void HookContext::nativeSpecializeAppProcess_pre() {
g_ctx = this; g_ctx = this;
flags[APP_SPECIALIZE] = true;
process = env->GetStringUTFChars(args.app->nice_name, nullptr);
if (flags[APP_FORK_AND_SPECIALIZE]) {
ZLOGV("pre forkAndSpecialize [%s]\n", process);
} else {
ZLOGV("pre specialize [%s]\n", process);
// App specialize does not check FD // App specialize does not check FD
flags[SKIP_CLOSE_LOGD_FD] = true; flags[SKIP_CLOSE_LOGD_FD] = true;
} process = env->GetStringUTFChars(args.app->nice_name, nullptr);
ZLOGV("pre specialize [%s]\n", process);
vector<int> module_fds; app_specialize_pre();
int fd = remote_get_info(args.app->uid, process, &info_flags, module_fds);
if ((info_flags & UNMOUNT_MASK) == UNMOUNT_MASK) {
ZLOGI("[%s] is on the denylist\n", process);
flags[DO_REVERT_UNMOUNT] = true;
} else if (fd >= 0) {
run_modules_pre(module_fds);
}
close(fd);
} }
void HookContext::nativeSpecializeAppProcess_post() { void HookContext::nativeSpecializeAppProcess_post() {
if (flags[APP_FORK_AND_SPECIALIZE]) {
ZLOGV("post forkAndSpecialize [%s]\n", process);
} else {
ZLOGV("post specialize [%s]\n", process); ZLOGV("post specialize [%s]\n", process);
} app_specialize_post();
env->ReleaseStringUTFChars(args.app->nice_name, process);
run_modules_post();
if (info_flags & PROCESS_IS_MAGISK_APP) {
setenv("ZYGISK_ENABLED", "1", 1);
}
// Cleanups
g_ctx = nullptr;
close(logd_fd.exchange(-1));
android_logging();
if (!flags[APP_FORK_AND_SPECIALIZE]) {
unload_zygisk(); unload_zygisk();
} }
}
void HookContext::nativeForkSystemServer_pre() { void HookContext::nativeForkSystemServer_pre() {
fork_pre(); ZLOGV("pre forkSystemServer\n");
flags[SERVER_FORK_AND_SPECIALIZE] = true; flags[SERVER_FORK_AND_SPECIALIZE] = true;
fork_pre();
if (pid != 0) if (pid != 0)
return; return;
ZLOGV("pre forkSystemServer\n");
vector<int> module_fds; vector<int> module_fds;
int fd = remote_get_info(1000, "system_server", &info_flags, module_fds); int fd = remote_get_info(1000, "system_server", &info_flags, module_fds);
if (fd >= 0) { if (fd >= 0) {
@ -631,19 +622,20 @@ void HookContext::nativeForkSystemServer_post() {
} }
void HookContext::nativeForkAndSpecialize_pre() { void HookContext::nativeForkAndSpecialize_pre() {
fork_pre(); process = env->GetStringUTFChars(args.app->nice_name, nullptr);
flags[APP_FORK_AND_SPECIALIZE] = true; flags[APP_FORK_AND_SPECIALIZE] = true;
ZLOGV("pre forkAndSpecialize [%s]\n", process);
fork_pre();
if (pid == 0) { if (pid == 0) {
nativeSpecializeAppProcess_pre(); app_specialize_pre();
sanitize_fds();
} else {
setup_fd_ignore();
} }
sanitize_fds();
} }
void HookContext::nativeForkAndSpecialize_post() { void HookContext::nativeForkAndSpecialize_post() {
if (pid == 0) { if (pid == 0) {
nativeSpecializeAppProcess_post(); ZLOGV("post forkAndSpecialize [%s]\n", process);
app_specialize_post();
} }
fork_post(); fork_post();
} }