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topjohnwu 2023-11-09 14:35:49 -08:00
parent 977c981265
commit 6d6f14fcb3
3 changed files with 76 additions and 74 deletions
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18
native/src/core/zygisk/hook.cpp
View File

@ -37,7 +37,7 @@ static bool should_unmap_zygisk = false;
ret (*old_##func)(__VA_ARGS__); \
ret new_##func(__VA_ARGS__)
DCL_HOOK_FUNC(void, androidSetCreateThreadFunc, void *func) {
DCL_HOOK_FUNC(static void, androidSetCreateThreadFunc, void *func) {
ZLOGD("androidSetCreateThreadFunc\n");
hook_jni_env();
old_androidSetCreateThreadFunc(func);
@ -49,14 +49,14 @@ DCL_HOOK_FUNC(int, fork) {
}
// Unmount stuffs in the process's private mount namespace
DCL_HOOK_FUNC(int, unshare, int flags) {
DCL_HOOK_FUNC(static int, unshare, int flags) {
int res = old_unshare(flags);
if (g_ctx && (flags & CLONE_NEWNS) != 0 && res == 0 &&
// For some unknown reason, unmounting app_process in SysUI can break.
// This is reproducible on the official AVD running API 26 and 27.
// Simply avoid doing any unmounts for SysUI to avoid potential issues.
(g_ctx->info_flags & PROCESS_IS_SYS_UI) == 0) {
if (g_ctx->flags[DO_REVERT_UNMOUNT]) {
if (g_ctx->flags & DO_REVERT_UNMOUNT) {
revert_unmount();
}
// Restore errno back to 0
@ -66,7 +66,7 @@ DCL_HOOK_FUNC(int, unshare, int flags) {
}
// This is the last moment before the secontext of the process changes
DCL_HOOK_FUNC(int, selinux_android_setcontext,
DCL_HOOK_FUNC(static int, selinux_android_setcontext,
uid_t uid, bool isSystemServer, const char *seinfo, const char *pkgname) {
// Pre-fetch logd before secontext transition
zygisk_get_logd();
@ -74,8 +74,8 @@ DCL_HOOK_FUNC(int, selinux_android_setcontext,
}
// Close file descriptors to prevent crashing
DCL_HOOK_FUNC(void, android_log_close) {
if (g_ctx == nullptr || !g_ctx->flags[SKIP_CLOSE_LOG_PIPE]) {
DCL_HOOK_FUNC(static void, android_log_close) {
if (g_ctx == nullptr || !(g_ctx->flags & SKIP_CLOSE_LOG_PIPE)) {
// This happens during forks like nativeForkApp, nativeForkUsap,
// nativeForkSystemServer, and nativeForkAndSpecialize.
zygisk_close_logd();
@ -86,7 +86,7 @@ DCL_HOOK_FUNC(void, android_log_close) {
// We cannot directly call `dlclose` to unload ourselves, otherwise when `dlclose` returns,
// it will return to our code which has been unmapped, causing segmentation fault.
// Instead, we hook `pthread_attr_destroy` which will be called when VM daemon threads start.
DCL_HOOK_FUNC(int, pthread_attr_destroy, void *target) {
DCL_HOOK_FUNC(static int, pthread_attr_destroy, void *target) {
int res = old_pthread_attr_destroy((pthread_attr_t *)target);
// Only perform unloading on the main thread
@ -111,7 +111,7 @@ DCL_HOOK_FUNC(int, pthread_attr_destroy, void *target) {
}
// it should be safe to assume all dlclose's in libnativebridge are for zygisk_loader
DCL_HOOK_FUNC(int, dlclose, void *handle) {
DCL_HOOK_FUNC(static int, dlclose, void *handle) {
static bool kDone = false;
if (!kDone) {
ZLOGV("dlclose zygisk_loader\n");
@ -126,7 +126,7 @@ DCL_HOOK_FUNC(int, dlclose, void *handle) {
// -----------------------------------------------------------------
HookContext::HookContext(JNIEnv *env, void *args) :
env(env), args{args}, process(nullptr), pid(-1), info_flags(0),
env(env), args{args}, process(nullptr), pid(-1), flags(0), info_flags(0),
hook_info_lock(PTHREAD_MUTEX_INITIALIZER) { g_ctx = this; }
HookContext::~HookContext() {

112
native/src/core/zygisk/module.cpp
View File

@ -98,7 +98,7 @@ void ZygiskModule::setOption(zygisk::Option opt) {
return;
switch (opt) {
case zygisk::FORCE_DENYLIST_UNMOUNT:
g_ctx->flags[DO_REVERT_UNMOUNT] = true;
g_ctx->flags |= DO_REVERT_UNMOUNT;
break;
case zygisk::DLCLOSE_MODULE_LIBRARY:
unload = true;
@ -203,45 +203,6 @@ bool HookContext::plt_hook_commit() {
// -----------------------------------------------------------------
static int sigmask(int how, int signum) {
sigset_t set;
sigemptyset(&set);
sigaddset(&set, signum);
return sigprocmask(how, &set, nullptr);
}
void HookContext::fork_pre() {
// 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 (!is_child())
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 will be closed once out of scope
allowed_fds[dirfd(dir.get())] = false;
// logd_fd should be handled separately
if (int fd = zygisk_get_logd(); fd >= 0) {
allowed_fds[fd] = false;
}
}
void HookContext::fork_post() {
// Unblock SIGCHLD in case the original method didn't
sigmask(SIG_UNBLOCK, SIGCHLD);
}
void HookContext::sanitize_fds() {
zygisk_close_logd();
@ -296,7 +257,7 @@ void HookContext::sanitize_fds() {
}
bool HookContext::exempt_fd(int fd) {
if (flags[POST_SPECIALIZE] || flags[SKIP_CLOSE_LOG_PIPE])
if ((flags & POST_SPECIALIZE) || (flags & SKIP_CLOSE_LOG_PIPE))
return true;
if (!can_exempt_fd())
return false;
@ -304,6 +265,49 @@ bool HookContext::exempt_fd(int fd) {
return true;
}
bool HookContext::can_exempt_fd() const {
return (flags & APP_FORK_AND_SPECIALIZE) && args.app->fds_to_ignore;
}
static int sigmask(int how, int signum) {
sigset_t set;
sigemptyset(&set);
sigaddset(&set, signum);
return sigprocmask(how, &set, nullptr);
}
void HookContext::fork_pre() {
// 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 (!is_child())
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 will be closed once out of scope
allowed_fds[dirfd(dir.get())] = false;
// logd_fd should be handled separately
if (int fd = zygisk_get_logd(); fd >= 0) {
allowed_fds[fd] = false;
}
}
void HookContext::fork_post() {
// Unblock SIGCHLD in case the original method didn't
sigmask(SIG_UNBLOCK, SIGCHLD);
}
void HookContext::run_modules_pre(const vector<int> &fds) {
for (int i = 0; i < fds.size(); ++i) {
struct stat s{};
@ -312,14 +316,14 @@ void HookContext::run_modules_pre(const vector<int> &fds) {
continue;
}
android_dlextinfo info {
.flags = ANDROID_DLEXT_USE_LIBRARY_FD,
.library_fd = fds[i],
.flags = ANDROID_DLEXT_USE_LIBRARY_FD,
.library_fd = fds[i],
};
if (void *h = android_dlopen_ext("/jit-cache", RTLD_LAZY, &info)) {
if (void *e = dlsym(h, "zygisk_module_entry")) {
modules.emplace_back(i, h, e);
}
} else if (g_ctx->flags[SERVER_FORK_AND_SPECIALIZE]) {
} else if (flags & SERVER_FORK_AND_SPECIALIZE) {
ZLOGW("Failed to dlopen zygisk module: %s\n", dlerror());
}
close(fds[i]);
@ -335,20 +339,20 @@ void HookContext::run_modules_pre(const vector<int> &fds) {
}
for (auto &m : modules) {
if (flags[APP_SPECIALIZE]) {
if (flags & APP_SPECIALIZE) {
m.preAppSpecialize(args.app);
} else if (flags[SERVER_FORK_AND_SPECIALIZE]) {
} else if (flags & SERVER_FORK_AND_SPECIALIZE) {
m.preServerSpecialize(args.server);
}
}
}
void HookContext::run_modules_post() {
flags[POST_SPECIALIZE] = true;
flags |= POST_SPECIALIZE;
for (const auto &m : modules) {
if (flags[APP_SPECIALIZE]) {
if (flags & APP_SPECIALIZE) {
m.postAppSpecialize(args.app);
} else if (flags[SERVER_FORK_AND_SPECIALIZE]) {
} else if (flags & SERVER_FORK_AND_SPECIALIZE) {
m.postServerSpecialize(args.server);
}
m.tryUnload();
@ -356,7 +360,7 @@ void HookContext::run_modules_post() {
}
void HookContext::app_specialize_pre() {
flags[APP_SPECIALIZE] = true;
flags |= APP_SPECIALIZE;
vector<int> module_fds;
int fd = remote_get_info(args.app->uid, process, &info_flags, module_fds);
@ -369,7 +373,7 @@ void HookContext::app_specialize_pre() {
}
if ((info_flags & UNMOUNT_MASK) == UNMOUNT_MASK) {
ZLOGI("[%s] is on the denylist\n", process);
flags[DO_REVERT_UNMOUNT] = true;
flags |= DO_REVERT_UNMOUNT;
} else if (fd >= 0) {
run_modules_pre(module_fds);
}
@ -419,7 +423,7 @@ void HookContext::nativeSpecializeAppProcess_pre() {
process = env->GetStringUTFChars(args.app->nice_name, nullptr);
ZLOGV("pre specialize [%s]\n", process);
// App specialize does not check FD
flags[SKIP_CLOSE_LOG_PIPE] = true;
flags |= SKIP_CLOSE_LOG_PIPE;
app_specialize_pre();
}
@ -430,7 +434,7 @@ void HookContext::nativeSpecializeAppProcess_post() {
void HookContext::nativeForkSystemServer_pre() {
ZLOGV("pre forkSystemServer\n");
flags[SERVER_FORK_AND_SPECIALIZE] = true;
flags |= SERVER_FORK_AND_SPECIALIZE;
fork_pre();
if (is_child()) {
@ -450,7 +454,7 @@ void HookContext::nativeForkSystemServer_post() {
void HookContext::nativeForkAndSpecialize_pre() {
process = env->GetStringUTFChars(args.app->nice_name, nullptr);
ZLOGV("pre forkAndSpecialize [%s]\n", process);
flags[APP_FORK_AND_SPECIALIZE] = true;
flags |= APP_FORK_AND_SPECIALIZE;
fork_pre();
if (is_child()) {

20
native/src/core/zygisk/module.hpp
View File

@ -202,15 +202,13 @@ private:
extern HookContext *g_ctx;
extern int (*old_fork)(void);
enum {
POST_SPECIALIZE,
APP_FORK_AND_SPECIALIZE,
APP_SPECIALIZE,
SERVER_FORK_AND_SPECIALIZE,
DO_REVERT_UNMOUNT,
SKIP_CLOSE_LOG_PIPE,
FLAG_MAX
enum : uint32_t {
POST_SPECIALIZE = (1u << 0),
APP_FORK_AND_SPECIALIZE = (1u << 1),
APP_SPECIALIZE = (1u << 2),
SERVER_FORK_AND_SPECIALIZE = (1u << 3),
DO_REVERT_UNMOUNT = (1u << 4),
SKIP_CLOSE_LOG_PIPE = (1u << 5),
};
#define MAX_FD_SIZE 1024
@ -231,7 +229,7 @@ struct HookContext {
std::list<ZygiskModule> modules;
int pid;
std::bitset<FLAG_MAX> flags;
uint32_t flags;
uint32_t info_flags;
std::bitset<MAX_FD_SIZE> allowed_fds;
std::vector<int> exempted_fds;
@ -266,8 +264,8 @@ struct HookContext {
void sanitize_fds();
bool exempt_fd(int fd);
bool can_exempt_fd() const;
bool is_child() const { return pid <= 0; }
bool can_exempt_fd() const { return flags[APP_FORK_AND_SPECIALIZE] && args.app->fds_to_ignore; }
// Compatibility shim
void plt_hook_register(const char *regex, const char *symbol, void *fn, void **backup);