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Make sure magisk daemon won't get killed by init

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According to this comment in #1880:
https://github.com/topjohnwu/Magisk/issues/1880#issuecomment-546657588

If Linux recycled our PPID, and coincidentally the process that reused
the PPID is root, AND init wants to kill the whole process group,
magiskd will get killed as a result.

There is no real way to block a SIGKILL signal, so we simply make sure
our daemon PID is the process group leader by renaming the directory.

Close #1880
This commit is contained in:
topjohnwu 2019-10-31 01:57:47 -04:00
parent 31e003bda5
commit e7155837d7
1 changed files with 8 additions and 0 deletions
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8
native/jni/core/daemon.cpp
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@ -210,9 +210,17 @@ int connect_daemon(bool create) {
exit(1);
}
int ppid = getpid();
LOGD("client: launching new main daemon process\n");
if (fork_dont_care() == 0) {
close(fd);
// Make sure ppid is not in acct
char src[64], dest[64];
sprintf(src, "/acct/uid_0/pid_%d", ppid);
sprintf(dest, "/acct/uid_0/pid_%d", getpid());
rename(src, dest);
main_daemon();
}