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SIGSTOP any possible process ASAP

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Shut down any UID matching process and resume if it turns out not to
be our target. Since we will record every single process we have ever
paused, this means that the same process will not be paused erroneously
for another time.

This is an optimization to hijack the app as soon as possible.
This commit is contained in:
topjohnwu 2019-03-02 04:24:41 -05:00
parent 7203e7df5c
commit d8cd2031c7
2 changed files with 23 additions and 20 deletions
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37
native/jni/magiskhide/proc_monitor.cpp
View File

@ -46,6 +46,7 @@ static inline void lazy_unmount(const char* mountpoint) {
LOGD("hide_daemon: Unmounted (%s)\n", mountpoint);
}
#if 0
static inline int parse_ppid(const int pid) {
char path[32];
int ppid;
@ -61,6 +62,7 @@ static inline int parse_ppid(const int pid) {
return ppid;
}
#endif
static void hide_daemon(int pid) {
RunFinally fin([=]() -> void {
@ -132,21 +134,26 @@ static bool check_pid(int pid, int uid) {
if (uid != get_uid(pid))
return true;
struct stat ns, pns;
int ppid;
// Make sure we can read mount namespace
if ((ppid = parse_ppid(pid)) < 0 || read_ns(pid, &ns) || read_ns(ppid, &pns))
return true;
// mount namespace is not separated, we only unmount once
if (ns.st_dev == pns.st_dev && ns.st_ino == pns.st_ino)
struct stat ns;
if (read_ns(pid, &ns))
return true;
// Check if it's a process we haven't already hijacked
// Check if we have already seen it before
auto pos = pid_ns_map.find(pid);
if (pos != pid_ns_map.end() && pos->second == ns.st_ino)
return true;
// Will rather kill all just for one
if (kill(pid, SIGSTOP) == -1)
return true;
// Auto send resume signal if return
RunFinally resume([=]() -> void {
kill(pid, SIGCONT);
});
// Record this PID
pid_ns_map[pid] = ns.st_ino;
// Check whether process name match hide list
const char *process = nullptr;
for (auto &proc : uid_proc_map[uid])
@ -156,20 +163,14 @@ static bool check_pid(int pid, int uid) {
if (!process)
return true;
// Send pause signal ASAP
if (kill(pid, SIGSTOP) == -1)
return true;
pid_ns_map[pid] = ns.st_ino;
LOGI("proc_monitor: [%s] UID=[%d] PID=[%d] ns=[%llu]\n", process, uid, pid, ns.st_ino);
/*
* The setns system call do not support multithread processes
* We have to fork a new process, setns, then do the unmounts
*/
// Disable auto resume PID, and let the daemon do it
resume.disable();
if (fork_dont_care() == 0)
hide_daemon(pid);
// We found what we want, stop traversal
return false;
}

6
native/jni/utils/include/utils.h
View File

@ -162,10 +162,12 @@ class RunFinally {
public:
explicit RunFinally(std::function<void()> &&fn): fn(std::move(fn)) {}
~RunFinally() { fn(); }
void disable() { fn = nullptr; }
~RunFinally() { if (fn) fn(); }
private:
const std::function<void ()> fn;
std::function<void ()> fn;
};
// file.cpp