cat >>/sbin/runas<<'EOF'
#!/bin/sh
exec ${PERL-perl} -Swx $0 ${1+"$@"}
#!perl [perl will skip all lines in this file before this line]
# with --- run program with special properties
# Copyright (C) 1995, 2000, 2002 Noah S. Friedman
# Author: Noah Friedman <friedman@splode.com>
# Created: 1995-08-14
# $Id: with,v 1.12 2004/02/16 22:51:49 friedman Exp $
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, you can either send email to this
# program's maintainer or write to: The Free Software Foundation,
# Inc.; 59 Temple Place, Suite 330; Boston, MA 02111-1307, USA.
# Commentary:
# TODO: create optional socket streams for stdin or stdout before invoking
# subprocess.
# Code:
use Getopt::Long;
use POSIX qw(setsid);
use Symbol;
use strict;
(my $progname = $0) =~ s|.*/||;
my $bgfn;
my $bgopt = 0;
my $opt_cwd;
my $opt_egid;
my $opt_euid;
my $opt_gid;
my $opt_groups;
my @opt_include;
my $opt_name;
my $opt_pgrp;
my $opt_priority;
my $opt_root;
my $opt_uid;
my $opt_umask;
my $opt_foreground = 0;
sub err
{
my $fh = (ref ($_[0]) ? shift : *STDERR{IO});
print $fh join (": ", $progname, @_), "\n";
exit (1);
}
sub get_includes
{
unshift @INC, @_;
push (@INC,
"$ENV{HOME}/lib/perl",
"$ENV{HOME}/lib/perl/include");
eval { require "syscall.ph" } if defined $opt_groups;
}
sub numberp
{
defined $_[0] && $_[0] =~ m/^-?\d+$/o;
}
sub group2gid
{
my $g = shift;
return $g if numberp ($g);
my $gid = getgrnam ($g);
return $gid if defined $gid && numberp ($gid);
err ($g, "no such group");
}
sub user2uid
{
my $u = shift;
return $u if numberp ($u);
my $uid = getpwnam ($u);
return $uid if defined $uid && numberp ($uid);
err ($u, "no such user");
}
sub set_cwd
{
my $d = shift;
chdir ($d) || err ("chdir", $d, $!);
}
sub set_egid
{
my $sgid = group2gid (shift);
my $egid = $) + 0;
$) = $sgid;
err ($sgid, "cannot set egid", $!) if ($) == $egid && $egid != $sgid);
}
sub set_gid
{
my $sgid = group2gid (shift);
my $rgid = $( + 0;
my $egid = $) + 0;
$( = $sgid;
$) = $sgid;
err ($sgid, "cannot set rgid", $!) if ($( == $rgid && $rgid != $sgid);
err ($sgid, "cannot set egid", $!) if ($) == $egid && $egid != $sgid);
}
sub big_endian_p
{
my $x = 1;
my @y = unpack ("c2", pack ("i", $x));
return ($y[0] == 1) ? 0 : 1;
}
# This function is more complex than it ought to be because perl does not
# export the setgroups function. It exports the getgroups function by
# making $( and $) return multiple values in the form of a space-separated
# string, but you cannot *set* the group list by assigning those variables.
# There is no portable way to determine what size gid_t is, so we must guess.
sub set_groups
{
my @glist = sort { $a <=> $b } map { group2gid ($_) } split (/[ ,]/, shift);
my $expected = join (" ", $(+0, reverse @glist);
my @p = (big_endian_p() ? ("n", "N", "i") : ("v", "V", "i"));
for my $c (@p)
{
err ("setgroups", $!)
if (syscall (&SYS_setgroups, @glist+0, pack ("$c*", @glist)) == -1);
return if ("$(" eq $expected);
}
err ("setgroups", "Could not determine gid_t");
}
sub set_pgrp
{
setpgrp ($$, shift) || err ("setpgrp", $!);
}
sub set_priority
{
my $prio = shift () + 0;
setpriority (0, 0, $prio) || err ("setpriority", $prio, $!);
}
sub set_root
{
my $d = shift;
chroot ($d) || err ("chroot", $d, $!);
chdir ("/");
}
sub set_euid
{
my $suid = user2uid (shift);
my $euid = $>;
$> = $suid;
err ($suid, "cannot set euid", $!) if ($> == $euid && $euid != $suid);
}
sub set_uid
{
my $suid = user2uid (shift);
my $ruid = $<;
my $euid = $>;
$< = $suid;
$> = $suid;
err ($suid, "cannot set ruid", $!) if ($< == $ruid && $ruid != $suid);
err ($suid, "cannot set euid", $!) if ($> == $euid && $euid != $suid);
}
sub background
{
my $pid = fork;
die "$@" if $pid < 0;
if ($pid == 0)
{
# Backgrounded programs may expect to be able to read input from the
# user if stdin is a tty, but we will no longer have any job control
# management because of the double fork and exit. This can result in
# a program either blocking on input (if still associated with a
# controlling terminal) and stopping, or stealing input from a
# foreground process (e.g. a shell). So redirect stdin to /dev/null.
open (STDIN, "< /dev/null") if (-t STDIN);
return *STDERR{IO};
}
exit (0) unless $opt_foreground;
wait;
exit ($?);
}
sub dosetsid
{
background ();
setsid (); # dissociate from controlling terminal
return *STDERR{IO};
}
sub daemon
{
# Don't allow any file descriptors, including stdin, stdout, or
# stderr to be propagated to children.
$^F = -1;
dosetsid ();
# Duped in case we've closed stderr but can't exec anything.
my $saved_stderr = gensym;
open ($saved_stderr, ">&STDERR");
close (STDERR);
close (STDOUT);
close (STDIN);
return $saved_stderr;
}
sub notty
{
# Don't allow any file descriptors other than stdin, stdout, or stderr to
# be propagated to children.
$^F = 2;
dosetsid ();
# Duped in case we've closed stderr but can't exec anything.
my $saved_stderr = gensym;
open ($saved_stderr, ">&STDERR");
open (STDIN, "+</dev/null");
open (STDERR, "+<&STDIN");
open (STDOUT, "+<&STDIN");
return $saved_stderr;
}
sub set_bg_option
{
my %bgfntbl =
( 1 => \&background,
2 => \&daemon,
4 => \¬ty,
8 => \&dosetsid,
);
$bgopt = $_[0];
$bgfn = $bgfntbl{$bgopt};
}
sub parse_options
{
Getopt::Long::config (qw(bundling autoabbrev require_order));
my $succ = GetOptions
("h|help", sub { usage () },
"c|cwd=s", \$opt_cwd,
"d|display=s", \$ENV{DISPLAY},
"H|home=s", \$ENV{HOME},
"G|egid=s", \$opt_egid,
"g|gid=s", \$opt_gid,
"I|include=s@", \@opt_include,
"l|groups=s", \$opt_groups,
"m|umask=s", \$opt_umask,
"n|name=s", \$opt_name,
"P|priority=i", \$opt_priority,
"p|pgrp=i", \$opt_pgrp,
"r|root=s", \$opt_root,
"U|euid=s", \$opt_euid,
"u|uid=s", \$opt_uid,
"f|fg|foreground", \$opt_foreground,
"b|bg|background", sub { set_bg_option (1); $opt_foreground = 0 },
"a|daemon|demon", sub { set_bg_option (2) },
"N|no-tty|notty", sub { set_bg_option (4) },
"s|setsid", sub { set_bg_option (8) },
);
usage () unless $succ;
my $n = 0;
do { $n++ if $bgopt & 1 } while ($bgopt >>= 1);
err ("Can only specify one of --background, --daemon, --notty, or --setsid")
if ($n > 1);
}
sub usage
{
print STDERR "$progname: @_\n\n" if @_;
print STDERR "Usage: $progname {options} [command {args...}]\n
Options are:
-h, --help You're looking at it.
-D, --debug Turn on interactive debugging in perl.
-I, --include DIR Include DIR in \@INC path for perl.
This option may be specified multiple times to append
search paths to perl.
-d, --display DISP Run with DISP as the X server display.
-H, --home HOME Set \$HOME.
-n, --name ARGV0 Set name of running program (argv[0]).
-c, --cwd DIR Run with DIR as the current working directory.
This directory is relative to the root directory as
specified by \`--root', or \`/'.
-r, --root ROOT Set root directory (via \`chroot' syscall) to ROOT.
-G, --egid EGID Set \`effective' group ID.
-g, --gid GID Set both \`real' and \`effective' group ID.
-l, --groups GLIST Set group list to comma-separated GLIST.
-U, --euid EUID Set \`effective' user ID.
-u, --uid UID Set both \`real' and \`effective' user ID.
-m, --umask UMASK Set umask.
-P, --priority NICE Set scheduling priority to NICE (-20 to 20).
-p, --pgrp PGRP Set process group.
The following options cause the resulting process to be backgrounded
automatically but differ in various ways:
-b, --background Run process in background. This is the default with
the --daemon, --no-tty, and --setsid options.
-f, --foreground Do not put process into the background when using
the --daemon, --no-tty, and --setsid options.
In all other cases the default is to remain in the
foreground.
-a, --daemon Run process in \"daemon\" mode.
This closes stdin, stdout, and stderr, dissociates
the process from any controlling terminal, and
backgrounds the process.
-N, --no-tty Run process in background with no controlling
terminal and with stdin, stdout, and stderr
redirected to /dev/null.
-s, --setsid Dissociate from controlling terminal.
This automatically backgrounds the process but
does not redirect any file descriptors.\n";
exit (1);
}
sub main
{
parse_options ();
usage () unless @ARGV;
get_includes (@opt_include);
umask (oct ($opt_umask)) if defined $opt_umask;
set_gid ($opt_gid) if defined $opt_gid;
set_egid ($opt_egid) if defined $opt_egid;
set_groups ($opt_groups) if defined $opt_groups;
set_root ($opt_root) if defined $opt_root;
set_cwd ($opt_cwd) if defined $opt_cwd;
set_priority ($opt_priority) if defined $opt_priority;
set_uid ($opt_uid) if defined $opt_uid;
set_euid ($opt_euid) if defined $opt_euid;
my $stderr = $bgfn ? &$bgfn () : *STDERR{IO};
my $runprog = $ARGV[0];
if ($opt_name)
{
shift @ARGV;
unshift @ARGV, $opt_name;
}
local $^W = 0; # avoid implicit warnings from exec
exec ($runprog @ARGV) || err ($stderr, "exec", $runprog, $!);
}
main ();
# local variables:
# mode: perl
# eval: (auto-fill-mode 1)
# end:
# with ends here
EOF