#!/usr/bin/perl -w
# $Revision: 1.11 $
# Luis Mondesi < lemsx1@gmail.com >
#
# DESCRIPTION: set up a chroot environment for a binary
#
# USAGE: cd /chroot/path && chroot_this.pl /path/to/program
#
# LICENSE: GPL
#
# NOTES:
# This script just does the right thing for the given program passed to it
# to setup a full chroot environment you will need all the common UNIX utils
# used by the program you passed as an argument.
# Here is an example of what you would need if you want to setup ssh/sftp
# chrooted on Fedora (with privilege separation):
#
# * /bin/{cp, ls, mkdir, mv, rm, rmdir, sh}: for i in cp ls mkdir mv rm rmdir sh; do chroot_this.pl /bin/$i; done
# * /usr/libexec/sftp-server: chroot_this.pl /usr/libexec/openssh/sftp-server
# * pam: mkdir -p etc/pam.d; cp -r /etc/pam.d/* etc/pam.d/
# * libpam: cp -r /lib/libpam* lib
# - cp /lib/libnss_files* lib
# - mkdir -p lib/security; chroot_this.pl `find /lib/security/ -depth`
# - mkdir -p etc/security; cp -r /etc/security/*.conf etc/security
# * ssh: mkdir -p etc/ssh; cp -a /etc/ssh/* etc/ssh/
# * /etc/nsswitch.conf: mkdir etc; cat > etc/nsswitch.conf <<-FIN
# passwd: files
# group: files
# shadow: files
# FIN
# * /etc/{passwd,shadow,group}:
# mkdir etc; cat > $CHROOTDIR/etc/passwd <<-FIN
# root:x:0:0:Root:/root:/bin/bash
# nobody:x:65534:65534:nobody:/:/bin/false
# sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
# FIN
# cat > etc/shadow <<-FIN
# root:*:11142:0:99999:7:::
# nobody:*:11142:0:99999:7:::
# sshd:!!:12871:0:99999:7:::
# FIN
# cat > etc/group <<-FIN
# root:x:0
# nogroup:x:65534:
# FIN
# * /var:
# - mkdir -p var/empty/sshd; chown root var/empty/sshd; chmod 0755 var/empty/sshd
# - mkdir -p var/log
# - mkdir -p var/run
# - mkdir -p var/tmp; chmod 1777 var/tmp
# * /tmp: mkdir tmp; chmod 1777 tmp
# * /etc/init.d/ssh: mkdir -p etc/init.d; cp /etc/init.d/ssh* etc/init.d/
# - cp /etc/init.d/functions etc/init.d/
# * Assorted kernel devices:
# - mknod dev/null c 1 3
# - mknod dev/zero c 1 5
# - mknod dev/urandom c 1 9
# - mknod dev/console c 5 1
#
# * Assorted directories:
# - mkdir -p etc/rc.d; cd etc/rc.d; ln -s ../init.d init.d
#
# * Assorted utilities:
# - /sbin/initlog: chroot_this.pl /sbin/initlog; cp /etc/initlog.conf etc/
# - /usr/bin/reset: chroot_this.pl /usr/bin/reset
# - /sbin/nologin: chroot_this.pl /sbin/nologin
# * Assorted libraries:
# - cp -a /lib/libssl* lib/
# - cp -a /usr/lib/libssl* usr/lib/
# - cp -a /usr/lib/libcrypt* usr/lib/
# * Assorted logging:
# - syslog-ng: add unix-stream(/path/to/chroot/dev/log) to your s_all source
# - syslog: edit /etc/sysconfig/syslog and add: -p /dev/log -a /path/to/chroot/dev/log
# * Assorted mounts:
# ssh doesn't like to work without this:
# - /dev/pts: mkdir dev/pts; mount -t devpts none dev/pts
#
# And finally, run: chroot /path/to/chrootdir
# And execute '/usr/sbin/sshd -dD' to test sshd in non-daemon debugging mode
# From a different shell/system, use "ssh -v -v user@server_or_ip" to test the client
# REFERENCES:
# * http://chrootssh.sourceforge.net/docs/chrootedsftp.html
# * http://www.bpfh.net/simes/computing/chroot-break.html
use strict;
$|++;
my $revision='1.11'; # version
# standard Perl modules
use Getopt::Long;
Getopt::Long::Configure('bundling');
#use POSIX; # cwd() ... man POSIX
use File::Spec::Functions qw/splitdir catdir/; # abs2rel() and other dir/filename specific
use File::Copy; # copy() and move()
#use File::Find; # find();
use File::Basename; # basename() && dirname()
#use FileHandle; # for progressbar
# Args:
my $PVERSION=0;
my $HELP=0;
my $DEBUG=0;
# get options
GetOptions(
# flags
'v|version' => \$PVERSION,
'h|help' => \$HELP,
'D|debug' => \$DEBUG,
# strings
#'o|option=s' => \$NEW_OPTION,
# numbers
#'a|another-option=i' => \$NEW_ANOTHER_OPTION,
);
if ( $HELP ) {
use Pod::Text;
my $parser = Pod::Text->new (sentence => 0, width => 78);
$parser->parse_from_file(File::Spec->catfile("$0"),
\*STDOUT);
exit 0;
}
if ( $PVERSION ) { print STDOUT ($revision,"
"); exit 0; }
my $usage = "usage: cd /path/to/chroot && chroot_this.pl /path/to/binary";
foreach my $bin ( @ARGV )
{
print STDERR "DEBUG: now doing: $bin
" if ( $DEBUG );
if ( ! -d $bin and -x $bin )
{
umask(0222); # make binaries executable and not writable
my $binchrootedpath = dirname($bin);
$binchrootedpath =~ s,^/,,; # removes first /
_mkdir($binchrootedpath); # recursively makes needed dirs
my $binchrootedpathnamed = "$binchrootedpath/".basename($bin);
if ( copy($bin,$binchrootedpathnamed) )
{
chmod (0555,$binchrootedpathnamed);
_success($binchrootedpathnamed);
} else {
warn ("*** Could not copy $bin to $binchrootedpathnamed ***");
}
# get dependencies
my $linked_deps = qx/ldd $bin/;
#print STDERR "DEBUG: dependancies for: $bin
$linked_deps
" if ( $DEBUG );
foreach my $lib ( split(/
/,$linked_deps) )
{
my $libchrootedpath = "";
$lib =~ s/\s*\(0x[0-9a-fA-F]+\)\s*$//; # cleaned: (0x00000da)
my ($libname,$libpath) = split(/\s*=>\s*/,$lib); # splitted by =>
next if ( ! defined($libpath) or $libpath =~ /^\s*$/ );
if ( -r $libpath ) # can we read this library name?
{
($libchrootedpath = $libpath) =~ s,^/,,; # cleaned first /
$libname =~ s/\s+//g; # cleaned spaces
_mkdir(dirname($libchrootedpath)); # recursively makes needed dirs
if ( ! -f "$libchrootedpath/$libname" )
{
if ( copy($libpath,$libchrootedpath) )
{
# surprisingly, in linux libraries must be exec also
chmod (0555,"$libchrootedpath/$libname");
_success($libchrootedpath);
} else {
print STDERR "*** Copying $libpath to $libchrootedpath failed! ***
";
print STDERR "$libpath: $!
";
}
} else {
print STDERR "$libchrootedpath already exists
";
}
} else {
no warnings;
print STDERR "library '$libpath' is not valid from 'ldd $bin'
";
print STDERR "try copying this file by hand.
";
}
}
} else {
print STDERR $usage,"
","'$bin' Non-executable
";
}
}
# @desc implements `mkdir -p`
sub _mkdir
{
my $old_umask = umask(0022); # make dirs executable, readable and writable
my $path = shift;
my $root = ( $path =~ m,^([/|\\|:]), ) ? $1 : ""; # relative or full path?
my @dirs = splitdir($path);
my $last = "";
my $flag=1;
foreach (@dirs)
{
next if ( $_ =~ m/^\s*$/ );
$last = ( $flag > 1 ) ? catdir($last,$_) : "$root"."$_" ;
mkdir ($last) if ( ! -d $last);
$flag++;
}
umask($old_umask); # reset umask
return $flag; # number of directories created
}
sub _success
{
my $str = shift;
print STDOUT "$str copied successfully
" if ($DEBUG);
}
__END__
=head1 NAME
chroot_this - chroot_this script by Luis Mondesi <lemsx1@gmail.com>
=head1 SYNOPSIS
B<chroot_this> [-v,--version]
[-D,--debug]
[-h,--help]
/path/to/program1 [/path/to/program2 | ... ]
=head1 DESCRIPTION
This script allows you to setup a chroot environment for a list of binaries
=head1 OPTIONS
=over 8
=item -v,--version
prints version and exits
=item -D,--debug
enables debug mode
=item -h,--help
prints this help and exits
=cut
Tweets by @13m5
Advertisement