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#!/bin/perl
#
# Hacked by Alan Stebbens <aks@sgi.com> to setuid to the username if
# valid on this system. Written as a secure Perl script. To enable,
#
# chown root /usr/samba/bin/sambalp
# chmod u+s,+x /usr/samba/bin/sambalp
#
# If setuidshells is not enabled on your system, you must also do this:
#
# systune -i
# nosuidshells = 0
# y
# quit
#
# reboot
#
# This script will still work as a normal user; it will not try
# to setuid in this case.
#
# If the "$PSFIX" variable is set below...
#
# Workaround Win95 printer driver/Impressario bug by removing
# the PS check for available virtual memory. Note that this
# bug appears to be in all Win95 print drivers that generate
# PostScript; but is for certain there with a QMS-PS 810 (the
# printer type I configure on the Win95-side for printing with
# Samba).
#
# the perl script fixes 3 different bugs.
# 1. remove the JCL statements added by some HP printer drivers to the
# beginning of the postscript output.
# 2. Fix a bug in output from word files with long filenames. A non-printing
# character added to the end of the title comment by word is
# removed.
# 3. The VM fix described above.
#
#
# Modified for Perl4 compatibility.
#
$PROG = "sambalp";
$PSFIX = 1; # set to 0 if you don't want to run
# the "psfix" portion
# Untaint the PATH variable
@PATH = split(' ',<<EOF);
/usr/sbin /usr/bsd /sbin /usr/bin /bin /usr/lib /usr/local/bin
EOF
$ENV{'PATH'} = join(':',@PATH);
if ($#ARGV < 3) {
print STDERR "usage: $PROG printer file user system\n";
exit;
}
$printer = $ARGV[0];
$file = $ARGV[1];
$user = $ARGV[2];
$system = $ARGV[3];
open(LPSTAT,"/usr/bin/lpstat -t|") || die("Can't get printer list.\n");
@printers = ();
while (<LPSTAT>) {
next unless /^printer (\w+)/;
push(@printers,$1);
}
close LPSTAT;
# Create a hash list
@printers{@printers} = @printers;
# Untaint the printer name
if (defined($prtname = $printers{$printer})) {
$printer = $prtname;
} else {
die("Unknown printer: \"$printer\"\n");
}
if ($> == 0) { # are we root?
# yes -- then perform a taint checks and possibly do a suid check
# Untaint the file and system names (pretend to filter them)
$file = $file =~ /^(.*)/ ? $1 : die("Bad file: $file\n");
$system = $system =~ /^(.*)/ ? $1 : die("Bad system: $system\n");
# Get the valid users
setpwent;
%users = ();
while (@pwe = getpwent()) {
$uids{$pwe[0]} = $pwe[2];
$users{$pwe[2]} = $pwe[0];
}
endpwent();
# Check out the user -- if the user is a real user on this system,
# then become that user so that the printer header page looks right
# otherwise, remain as the default user (probably "nobody").
if (defined($uid = $uids{$user})) {
# before we change UID, we must ensure that the file is still
# readable after the UID change.
chown($uid, 9, $file); # make the file owned by the user
# Now, go ahead and become the user
$name = $users{$uid};
$> = $uid; # become the user
$< = $uid;
} else { # do untaint filtering
$name = $user =~ /^(\w+)/ ? $1 : die("Bad user: $user\n");
}
} else { # otherwise, just be me
$name = $user; # whomever that is
}
$lpcommand = "/usr/bin/lp -c -d$printer -t'$name on $system'";
# This code is from the original "psfix" but it has been completely
# rewritten for speed.
if ($PSFIX) { # are we running a "psfix"?
open(FILE, $file) || die("Can't read $file: $!\n");
open(LP, "|$lpcommand -") || die("Can't open pipe to \"lp\": $!\n");
select(LP);
while (<FILE>) { #
$_ =~ s/^\004//; # strip any ctrl-d's
if (/^\e%/) { # get rid of any non-postscript commands
while (<FILE>) { # remove text until next %!PS
s/^\001M//; # lenmark driver prefixes Ctrl-A M to %!PS
last if /^%!PS/;
}
last if eof(FILE);
} elsif (/^%%Title:/) { # fix bug in long titles from MS Word
s/.\r$/\r/; # remove trailing character on the title
} elsif (/^\/VM\?/) { # remove VM test
print "/VM? { pop } bind def\r\n";
while (<FILE>) { last if /def\r/; }
next; # don't print
}
print;
}
close FILE;
close LP;
} else { # we're not running psfix?
system("$lpcommand $file");
}
if ($file =~ m(^/)) {
# $file is a fully specified path
# Remove the file only if it lives in a directory ending in /tmp.
unlink($file) if ($file =~ m(/tmp/[^/]+$));
} else {
# $file is NOT a fully specified path
# Remove the file only if current directory ends in /tmp.
unlink($file) if (`pwd` =~ m(/tmp$));
}
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