[ale] Doing a chroot in Perl

[Jerry Yu]

what exactly is the permission on your jail / (aka, ScriptExecRoot)?

On 8/30/06, Christopher Fowler <cfowler at outpostsentinel.com> wrote:
>
> This is kinda strange.  On this same example I'm now outside of my
> chroot jail and I can not delete a file that is owned by me
> I created that file in the jail.  I've not figured out why I was able to
> do that.  Since the '/' of the jail is owned by root.
>
> [tomcat at sam-demo ScriptExecRoot]$ whoami
> tomcat
> [tomcat at sam-demo ScriptExecRoot]$ ls -l
> total 276
> drwxrwxr-x    2 root   root     4096 Aug 30 07:58 bin
> drwxr-xr-x   23 root   root   233472 Aug 26 18:25 dev
> drwxr-xr-x    2 root   root     4096 Aug 30 08:02 etc
> drwxr-xr-x    3 root   root     4096 Aug 26 18:20 home
> dr-xr-xr-x    2 root   root     4096 Aug 26 20:02 lib
> drwxr-xr-x    6 root   root     4096 Aug 27 14:54 opt
> -rw-r--r--    1 tomcat tomcat   6689 Aug 30 08:02 out.txt
> dr-xr-xr-x  202 root   root        0 Apr 18 05:32 proc
> drwxr-xr-x    2 root   root     4096 Aug 26 18:21 root
> drwxrwxr-x    2 root   root     4096 Aug 26 17:31 sbin
> drwxrwxrwt    2 root   root     4096 Aug 28 15:41 tmp
> drwxrwxr-x    4 root   root     4096 Aug 30 07:59 usr
>
> I'm outside the jail as user tomcat and I try to delete the file I
> created inside the jail as tomcat.  I can't do it.
>
> [tomcat at sam-demo ScriptExecRoot]$ rm out.txt
> rm: cannot remove `out.txt': Permission denied
>
>
>
> On Tue, 2006-08-29 at 12:35 -0400, Christopher Fowler wrote:
> > I doing something wrong in my test program.  This program takes an
> > argument and executes it in a chroot environment.  If not argument is
> > given it will simply execute the shell instead.
> >
> > This is part of my script execution that I asked about a week or so ago.
> > I am now going to extract the script from the database and place it in a
> > chroot environment.  I will then execute it from there.  I'm using this
> > test program before I integrate it into the main code.
> >
> > --- [ Cut Here ]-------------------------------------
> > #!/usr/bin/perl
> >
> > use POSIX qw/setuid setgid/;
> > use strict;
> >
> > # Globals
> > my $root = "/opt/SAM/ScriptExecRoot";
> >
> > sub main {
> >
> >   # Verify if proc is mounted
> >   # if not mount it for the user
> >   if(! -d "$root/proc/1") {
> >     system "mount -o bind /proc $root/proc";
> >   }
> >
> >
> >   # Setup default language
> >   # This root does not support locale
> >   # and perl needs this
> >   $ENV{'LANG'} = "C";
> >   $ENV{'PATH'} = "$ENV{'PATH'}:/sbin:/usr/sbin";
> >
> >   # Change our root and
> >   # set our uid
> >   chroot $root;
> >
> >   my ($name,$pass,$uid,$gid,undef,undef,undef,$dir) = getpwnam("tomcat")
> > or die;
> >
> >   setgid $uid;
> >   setuid $uid;
> >   chdir $dir;
> >
> >   # No argument?  Just exec a shell
> >   if($#ARGV == -1 ) {
> >     exec "/bin/sh"
> >       or die "exec $!\n";
> >   }
> >
> >   exec "/bin/sh", ("-c", @ARGV)
> >     or die "exec $!\n";
> > }
> >
> > exit main;
> > --- [ Cut Here ]-------------------------------------
> >
> > The problem is that I'm able to do stuff I should not be able to.
> >
> > Here is output
> >
> > --- [ Cut Here ]-------------------------------------
> > [root at sam-demo ScriptExecRoot]# bin/exec.pl
> >
> >
> > BusyBox v1.2.1 (2006.08.26-21:30+0000) Built-in shell (ash)
> > Enter 'help' for a list of built-in commands.
> >
> > $ ps > /
> > $ ls -l /out
> > -rw-r--r--    1 500      500          6998 Aug 26 23:42 /out
> > $
> > [root at sam-demo ScriptExecRoot]# ls -l
> > total 276
> > drwxrwxr-x    2 root   root     4096 Aug 26 19:42 bin
> > drwxr-xr-x   23 root   root   233472 Aug 26 18:25 dev
> > drwxr-xr-x    2 root   root     4096 Aug 26 19:28 etc
> > drwxr-xr-x    3 root   root     4096 Aug 26 18:20 home
> > dr-xr-xr-x    2 root   root     4096 Aug 26 19:29 lib
> > drwxr-xr-x    3 root   root     4096 Aug 26 17:58 opt
> > -rw-r--r--    1 tomcat tomcat   6998 Aug 26 19:42 out
> > dr-xr-xr-x  209 root   root        0 Apr 18 05:32 proc
> > drwxr-xr-x    2 root   root     4096 Aug 26 18:21 root
> > drwxrwxr-x    2 root   root     4096 Aug 26 17:31 sbin
> > drwxrwxrwt    2 root   root     4096 Aug 26 19:42 tmp
> > drwxrwxr-x    3 root   root     4096 Aug 26 17:29 usr
> > --- [ Cut Here ]-------------------------------------
> >
> > As you can see /out is owned by tomcat.tomcat but why was he able to
> > place anything in /out?  Probably something simple I'm not seeing or
> > forgot to do.
> >
> > Thanks,
> > Chris
> >
> >
> >
> > _______________________________________________
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> > Ale at ale.org
> > http://www.ale.org/mailman/listinfo/ale
>
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