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Always detach all child threads before leaving

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topjohnwu
2019-03-12 16:48:01 -04:00
parent a4a661bf34
commit dce0b6c05a
3 changed files with 44 additions and 39 deletions
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63
native/jni/magiskhide/proc_monitor.cpp
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@ -46,9 +46,8 @@ static map<int, vector<string_view>> uid_proc_map; /* uid -> list of process */
pthread_mutex_t monitor_lock;
#define PID_MAX 32768
static vector<bool> attaches(PID_MAX); /* true if pid should be monitored */
static vector<bool> attaches(PID_MAX); /* true if pid is monitored */
static vector<bool> detaches(PID_MAX); /* true if tid should be detached */
static vector<bool> unknowns(PID_MAX); /* true if pid/tid is in unknown state */
/********
* Utils
@ -170,7 +169,7 @@ void *update_uid_map(void*) {
static void hide_daemon(int pid) {
RunFinally fin([=]() -> void {
// Send resume signal
kill(pid, SIGCONT);
tgkill(pid, pid, SIGCONT);
_exit(0);
});
@ -247,7 +246,6 @@ static void term_thread(int) {
hide_set.clear();
std::fill(attaches.begin(), attaches.end(), false);
std::fill(detaches.begin(), detaches.end(), false);
std::fill(unknowns.begin(), unknowns.end(), false);
// Misc
hide_enabled = false;
pthread_mutex_destroy(&monitor_lock);
@ -268,6 +266,29 @@ static void term_thread(int) {
//#define PTRACE_LOG(fmt, args...) LOGD("PID=[%d] " fmt, pid, ##args)
#define PTRACE_LOG(...)
static void detach_pid(int pid, int signal = 0) {
char path[128];
xptrace(PTRACE_DETACH, pid, nullptr, signal);
// Detach all child threads too
sprintf(path, "/proc/%d/task", pid);
DIR *dir = opendir(path);
crawl_procfs(dir, [&](int tid) -> bool {
if (tid != pid) {
// Check if we should force a SIGSTOP
if (waitpid(tid, nullptr, __WALL | __WNOTHREAD | WNOHANG) == tid) {
PTRACE_LOG("detach thread [%d]\n", tid);
xptrace(PTRACE_DETACH, tid);
} else {
detaches[tid] = true;
tgkill(pid, tid, SIGSTOP);
}
}
return true;
});
closedir(dir);
}
static bool check_pid(int pid) {
char path[128];
char cmdline[1024];
@ -309,9 +330,9 @@ static bool check_pid(int pid) {
/* Finally this is our target!
* Detach from ptrace but should still remain stopped.
* The hide daemon will resume the process. */
xptrace(PTRACE_DETACH, pid, nullptr, SIGSTOP);
LOGI("proc_monitor: [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
PTRACE_LOG("target found\n");
LOGI("proc_monitor: [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
detach_pid(pid, SIGSTOP);
if (fork_dont_care() == 0)
hide_daemon(pid);
return true;
@ -319,7 +340,7 @@ static bool check_pid(int pid) {
}
}
PTRACE_LOG("not our target\n");
xptrace(PTRACE_DETACH, pid);
detach_pid(pid);
return true;
}
@ -387,17 +408,11 @@ void proc_monitor() {
// Non of our business now
attaches[pid] = false;
detaches[pid] = false;
unknowns[pid] = false;
ptrace(PTRACE_DETACH, pid, 0, 0);
}
});
if (!WIFSTOPPED(status)) {
// Nothing to do with us
PTRACE_LOG("terminate\n");
DETACH_AND_CONT;
}
if (detaches[pid]) {
PTRACE_LOG("detach\n");
if (!WIFSTOPPED(status) || detaches[pid]) {
PTRACE_LOG("detached\n");
DETACH_AND_CONT;
}
if (WSTOPSIG(status) == SIGTRAP && WEVENT(status)) {
@ -410,12 +425,6 @@ void proc_monitor() {
case PTRACE_EVENT_VFORK:
PTRACE_LOG("zygote forked: [%d]\n", msg);
attaches[msg] = true;
if (unknowns[msg]) {
/* Stop the child again to make sure
* we are monitoring the proper events */
unknowns[msg] = false;
tgkill(msg, msg, SIGSTOP);
}
break;
case PTRACE_EVENT_EXIT:
PTRACE_LOG("zygote exited with status: [%d]\n", msg);
@ -430,7 +439,6 @@ void proc_monitor() {
switch (WEVENT(status)) {
case PTRACE_EVENT_CLONE:
PTRACE_LOG("create new threads: [%d]\n", msg);
detaches[msg] = true;
if (attaches[pid] && check_pid(pid))
continue;
break;
@ -445,14 +453,9 @@ void proc_monitor() {
xptrace(PTRACE_CONT, pid);
}
} else if (WSTOPSIG(status) == SIGSTOP) {
if (attaches[pid]) {
PTRACE_LOG("SIGSTOP from zygote child\n");
xptrace(PTRACE_SETOPTIONS, pid, nullptr,
PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC | PTRACE_O_TRACEEXIT);
} else {
PTRACE_LOG("SIGSTOP from unknown\n");
unknowns[pid] = true;
}
PTRACE_LOG("SIGSTOP from child\n");
xptrace(PTRACE_SETOPTIONS, pid, nullptr,
PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC | PTRACE_O_TRACEEXIT);
xptrace(PTRACE_CONT, pid);
} else {
// Not caused by us, resend signal