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Preparation for hiding isolated processes

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topjohnwu
2020-12-30 15:55:53 -08:00
parent 3f9a64417b
commit 8e61080a4a
13 changed files with 271 additions and 216 deletions
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native/jni/magiskhide/proc_monitor.cpp
+77 -55
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@@ -1,6 +1,3 @@
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
@@ -61,13 +58,13 @@ static int parse_ppid(int pid) {
int ppid;
sprintf(path, "/proc/%d/stat", pid);
FILE *stat = fopen(path, "re");
if (stat == nullptr)
auto stat = open_file(path, "re");
if (!stat)
return -1;
// PID COMM STATE PPID .....
fscanf(stat, "%*d %*s %*c %d", &ppid);
fclose(stat);
fscanf(stat.get(), "%*d %*s %*c %d", &ppid);
return ppid;
}
@@ -89,20 +86,27 @@ void update_uid_map() {
string data_path(APP_DATA_DIR);
size_t len = data_path.length();
auto dir = open_dir(APP_DATA_DIR);
bool firstIteration = true;
for (dirent *entry; (entry = xreaddir(dir.get()));) {
data_path.resize(len);
data_path += '/';
data_path += entry->d_name;
data_path += entry->d_name; // multiuser user id
data_path += '/';
size_t user_len = data_path.length();
struct stat st;
for (auto &hide : hide_set) {
if (hide.first == ISOLATED_MAGIC) {
if (!firstIteration) continue;
// Setup isolated processes
uid_proc_map[-1].emplace_back(hide.second);
}
data_path.resize(user_len);
data_path += hide.first;
if (stat(data_path.data(), &st))
continue;
uid_proc_map[st.st_uid].emplace_back(hide.second);
}
firstIteration = false;
}
}
@@ -224,7 +228,7 @@ static bool check_pid(int pid) {
sprintf(path, "/proc/%d", pid);
if (stat(path, &st)) {
// Process killed unexpectedly, ignore
// Process died unexpectedly, ignore
detach_pid(pid);
return true;
}
@@ -237,7 +241,7 @@ static bool check_pid(int pid) {
if (auto f = open_file(path, "re")) {
fgets(cmdline, sizeof(cmdline), f.get());
} else {
// Process killed unexpectedly, ignore
// Process died unexpectedly, ignore
detach_pid(pid);
return true;
}
@@ -247,36 +251,59 @@ static bool check_pid(int pid) {
return false;
int uid = st.st_uid;
auto it = uid_proc_map.find(uid);
if (it != uid_proc_map.end()) {
for (auto &s : it->second) {
if (s == cmdline) {
// Double check whether ns is separated
read_ns(pid, &st);
bool mnt_ns = true;
for (auto &zit : zygote_map) {
if (zit.second.st_ino == st.st_ino &&
zit.second.st_dev == st.st_dev) {
mnt_ns = false;
break;
}
}
// For some reason ns is not separated, abort
if (!mnt_ns)
break;
auto it = uid_proc_map.end();
// Finally this is our target!
// Detach from ptrace but should still remain stopped.
// The hide daemon will resume the process.
PTRACE_LOG("target found\n");
LOGI("proc_monitor: [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
detach_pid(pid, SIGSTOP);
hide_daemon(pid);
return true;
if (uid % 100000 > 90000) {
// Isolated process
it = uid_proc_map.find(-1);
if (it == uid_proc_map.end())
goto not_target;
for (auto &s : it->second) {
if (str_starts(cmdline, s)) {
LOGI("proc_monitor: (isolated) [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
goto inject_and_hide;
}
}
}
PTRACE_LOG("[%s] not our target\n", cmdline);
it = uid_proc_map.find(uid);
if (it == uid_proc_map.end())
goto not_target;
for (auto &s : it->second) {
if (s != cmdline)
continue;
if (str_ends(s, "_zygote")) {
LOGI("proc_monitor: (app zygote) [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
goto inject_and_hide;
}
// Double check whether ns is separated
read_ns(pid, &st);
for (auto &zit : zygote_map) {
if (zit.second.st_ino == st.st_ino &&
zit.second.st_dev == st.st_dev) {
// For some reason ns is not separated, abort
goto not_target;
}
}
// Finally this is our target!
// Detach from ptrace but should still remain stopped.
// The hide daemon will resume the process.
LOGI("proc_monitor: [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
detach_pid(pid, SIGSTOP);
hide_daemon(pid);
return true;
}
not_target:
PTRACE_LOG("[%s] is not our target\n", cmdline);
detach_pid(pid);
return true;
inject_and_hide:
// TODO: handle isolated processes and app zygotes
detach_pid(pid);
return true;
}
@@ -324,7 +351,7 @@ static void new_zygote(int pid) {
}
#define WEVENT(s) (((s) & 0xffff0000) >> 16)
#define DETACH_AND_CONT { detach = true; continue; }
#define DETACH_AND_CONT { detach_pid(pid); continue; }
void proc_monitor() {
// Unblock some signals
@@ -354,9 +381,7 @@ void proc_monitor() {
setitimer(ITIMER_REAL, &interval, nullptr);
}
int status;
for (;;) {
for (int status;;) {
const int pid = waitpid(-1, &status, __WALL | __WNOTHREAD);
if (pid < 0) {
if (errno == ECHILD) {
@@ -370,38 +395,35 @@ void proc_monitor() {
}
continue;
}
bool detach = false;
run_finally f([&] {
if (detach)
// Non of our business now
detach_pid(pid);
});
if (!WIFSTOPPED(status) /* Ignore if not ptrace-stop */)
DETACH_AND_CONT;
if (WSTOPSIG(status) == SIGTRAP && WEVENT(status)) {
int event = WEVENT(status);
int signal = WSTOPSIG(status);
if (signal == SIGTRAP && event) {
unsigned long msg;
xptrace(PTRACE_GETEVENTMSG, pid, nullptr, &msg);
if (zygote_map.count(pid)) {
// Zygote event
switch (WEVENT(status)) {
switch (event) {
case PTRACE_EVENT_FORK:
case PTRACE_EVENT_VFORK:
PTRACE_LOG("zygote forked: [%d]\n", msg);
PTRACE_LOG("zygote forked: [%lu]\n", msg);
attaches[msg] = true;
break;
case PTRACE_EVENT_EXIT:
PTRACE_LOG("zygote exited with status: [%d]\n", msg);
PTRACE_LOG("zygote exited with status: [%lu]\n", msg);
[[fallthrough]];
default:
zygote_map.erase(pid);
DETACH_AND_CONT;
}
} else {
switch (WEVENT(status)) {
switch (event) {
case PTRACE_EVENT_CLONE:
PTRACE_LOG("create new threads: [%d]\n", msg);
PTRACE_LOG("create new threads: [%lu]\n", msg);
if (attaches[pid] && check_pid(pid))
continue;
break;
@@ -414,7 +436,7 @@ void proc_monitor() {
}
}
xptrace(PTRACE_CONT, pid);
} else if (WSTOPSIG(status) == SIGSTOP) {
} else if (signal == SIGSTOP) {
if (!attaches[pid]) {
// Double check if this is actually a process
attaches[pid] = is_process(pid);
@@ -432,8 +454,8 @@ void proc_monitor() {
}
} else {
// Not caused by us, resend signal
xptrace(PTRACE_CONT, pid, nullptr, WSTOPSIG(status));
PTRACE_LOG("signal [%d]\n", WSTOPSIG(status));
xptrace(PTRACE_CONT, pid, nullptr, signal);
PTRACE_LOG("signal [%d]\n", signal);
}
}
}