PTRACE_SEIZE not supported

[luser]

• Your Windows build number: Microsoft Windows [Version 10.0.16299.309]

• What you're doing and what's happening:

The PTRACE_SEIZE request to the ptrace syscall is not supported. Example program:

/* gcc -o ptrace-test ptrace.c */
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <unistd.h>

int main(int argc, char** argv) {
  pid_t pid = fork();
  if (pid == 0) {
    sleep(60);
    exit(0);
  }
  if (ptrace(PTRACE_SEIZE, pid, NULL, 0) == 0) {
    printf("ptrace succeeded\n");
  } else {
    perror("ptrace failed");
  }
  return 0;
}

Example output:

luser@DESKTOP-32V9ND8:/mnt/c/build$ gcc -o ptrace-test ptrace.c
luser@DESKTOP-32V9ND8:/mnt/c/build$ ./ptrace-test
ptrace failed: Invalid argument

• What's wrong / what should be happening instead:
  PTRACE_SEIZE should work similarly to PTRACE_ATTACH (which does work). Per the man page:

PTRACE_SEIZE (since Linux 3.4)
              Attach to the process specified in pid, making it a tracee of
              the calling process.  Unlike PTRACE_ATTACH, PTRACE_SEIZE does
              not stop the process.

This prevents rr from working, and I'm sure it impacts other programs as well.

[therealkenc]

Thanks for the excellent repro on PTRACE_SEIZE, since you weren't thanked earlier (we don't get enough of them). Better in WSL2.

[vishwaraj101]

Hi Getting error while using frida python inside wsl 2:
Using python 3.8.10 in ubuntu

➜ testbed ./fuzz.py
Traceback (most recent call last):
File "./fuzz.py", line 62, in
session = frida.attach(pid)
File "/home/raj/.local/lib/python3.8/site-packages/frida/init.py", line 62, in attach
return get_local_device().attach(target, **kwargs)
File "/home/raj/.local/lib/python3.8/site-packages/frida/core.py", line 26, in wrapper
return f(*args, **kwargs)
File "/home/raj/.local/lib/python3.8/site-packages/frida/core.py", line 156, in attach
return Session(self._impl.attach(self._pid_of(target)))
frida.NotSupportedError: unexpected error while attaching to process with pid 634 (PTRACE_SEIZE returned 'Invalid argument')