Re: saved IDs and exec (standard violation?)

[Marcus Brinkmann]

Hi,

here is the test program and the Makefile I used to reproduce this.  The
test program does not have a fork() anymore (I had one, but it messed up the
output and wasn't relevant anyway, so I removed it).

Here is the output on GNU/Linux:
marcus@ulysses[0]:/tmp$ make check
cc     savedid-test.c   -o savedid-test
cp savedid-test savedid-test-nogid
sudo chgrp utmp savedid-test
sudo chmod g+s savedid-test
./savedid-test
Startup: Real ID 1005, Effective ID 43.
Preexec: Real ID 1005, Effective ID 1005.
Startup: Real ID 1005, Effective ID 1005.
Seteuid: Real ID 1005, Effective ID 1005.

Here on GNU/Hurd:
marcus@drizzt:~$ make check
cc     savedid-test.c   -o savedid-test
cp savedid-test savedid-test-nogid
sudo chgrp utmp savedid-test
sudo chmod g+s savedid-test
./savedid-test
Startup: Real ID 1000, Effective ID 43.
Preexec: Real ID 1000, Effective ID 1000.
Startup: Real ID 1000, Effective ID 1000.
Seteuid: Real ID 1000, Effective ID 43.

Thanks,
Marcus

-- 
`Rhubarb is no Egyptian god.' Debian http://www.debian.org [EMAIL PROTECTED]
Marcus Brinkmann              GNU    http://www.gnu.org    [EMAIL PROTECTED]
[EMAIL PROTECTED]
http://www.marcus-brinkmann.de

#include <unistd.h>

int
main (int argc, char *argv[])
{
  int real_id = getgid ();
  int eff_id = getegid ();

  printf ("Startup: Real ID %i, Effective ID %i.\n", getgid (), getegid());

  if (argc > 1)
    {
      int old_saved_id = atoi (argv[1]);

      setegid (old_saved_id);
      printf ("Seteuid: Real ID %i, Effective ID %i.\n", getgid (), getegid());
    }
  else
    {
      char *args[] = { 0, 0, 0 };

      asprintf (&args[0], "%s-nogid", argv[0]);
      asprintf (&args[1], "%i", eff_id);
      setgid (real_id);
      printf ("Preexec: Real ID %i, Effective ID %i.\n", getgid (), getegid());
      execvp (args[0], args);
    }
  return 0;
}

all: savedid-test
        cp savedid-test savedid-test-nogid
        sudo chgrp utmp savedid-test
        sudo chmod g+s savedid-test

check: all
        ./savedid-test