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#!/usr/bin/perl -T
use strict;
my $uid = $<;
my $username = getpwuid($uid);
my $authorisation_file = '/etc/security/fileshare.conf';
my $authorisation_group = 'fileshare';
my $usage =
"usage: fileshareset --add <dir>
fileshareset --remove <dir>";
my $non_authorised =
qq(You are not authorised to use fileshare'ing
To grant you the rights, either:
- put "RESTRICT=no" in $authorisation_file
- put user "$username" in group "$authorisation_group");
my %exit_codes = reverse (
1 => $non_authorised,
2 => $usage,
# when adding
3 => "already exported",
4 => "invalid mount point",
# when removing
5 => "not exported",
255 => "various",
);
%ENV = ();
authorisation::check();
my $nfs_exports = nfs_exports::read();
if ($0 =~ /fileshareset/) {
my ($cmd, $dir) = @ARGV;
$< = $>;
@ARGV == 2 && ($cmd eq '--add' || $cmd eq '--remove') or error($usage);
verify_mntpoint($dir);
if ($cmd eq '--add') {
nfs_exports::add($nfs_exports, $dir);
} else {
nfs_exports::remove($nfs_exports, $dir);
}
nfs_exports::write($nfs_exports);
nfs_exports::update_server();
}
print "$_->{mntpoint}\n" foreach grep { own($_->{mntpoint}) } @$nfs_exports;
sub own { (stat($_[0]))[4] == $uid }
sub verify_mntpoint {
local ($_) = @_;
my $ok = 1;
$ok &&= m|^/|;
$ok &&= !m|/../|;
$ok &&= !m|[\0\n\r]|;
$ok &&= -d $_;
$ok &&= own($_);
$ok or error("invalid mount point");
}
sub error {
my ($string) = @_;
print STDERR "$string\n";
exit($exit_codes{$string} || 255);
}
sub member { my $e = shift; foreach (@_) { $e eq $_ and return 1 } 0 }
################################################################################
package authorisation;
sub read_conf {
local *F;
open F, $authorisation_file; # don't care if it's missing
my %conf;
foreach (<F>) {
s/#.*//; # remove comments
s/^\s+//;
s/\s+$//;
/^$/ and next;
my ($cmd, $value) = split('=', $_, 2);
$conf{$cmd} = $value || warn qq(suspicious line "$_" in $authorisation_file\n);
}
\%conf
}
sub check {
my $conf = read_conf();
if (lc($conf->{RESTRICT}) eq 'no') {
# ok, access granted for everybody
} else {
my @l;
while (@l = getgrent) {
last if $l[0] eq $authorisation_group;
}
::member($username, split(',', $l[3])) or ::error($non_authorised);
}
}
################################################################################
package nfs_exports;
sub read {
my $file = '/etc/exports';
open F, $file or return [];
my ($prev_raw, $prev_line, %e, @l);
my $line_nb = 0;
foreach my $raw (<F>) {
$line_nb++;
local $_ = $raw;
$raw .= "\n" if !/\n/;
s/#.*//; # remove comments
s/^\s+//;
s/\s+$//; # remove unuseful spaces to help regexps
if (/^$/) {
# blank lines ignored
$prev_raw .= $raw;
next;
}
if (/\\$/) {
# line continue across lines
chop; # remove the backslash
$prev_line .= "$_ ";
$prev_raw .= $raw;
next;
}
my $line = $prev_line . $_;
my $raw_line = $prev_raw . $raw;
($prev_line, $prev_raw) = ('', '');
my ($mntpoint, $options) = $line =~ /("[^"]*"|\S+)\s+(.*)/ or die "$file:$line_nb: bad line $line\n";
# You can also specify spaces or any other unusual characters in the
# export path name using a backslash followed by the character code as
# 3 octal digits.
$mntpoint =~ s/\\(\d{3})/chr(oct $1)/ge;
# not accepting weird characters that would break the output
$mntpoint =~ m/[\0\n\r]/ and die "i won't handle this";
push @l, { mntpoint => $mntpoint, option => $options, raw => $raw_line };
}
\@l;
}
sub find {
my ($nfs_exports, $mntpoint) = @_;
foreach (@$nfs_exports) {
$_->{mntpoint} eq $mntpoint and return $_;
}
undef;
}
sub add {
my ($nfs_exports, $mntpoint) = @_;
foreach (@$nfs_exports) {
$_->{mntpoint} eq $mntpoint and ::error("already exported");
}
push @$nfs_exports, { mntpoint => $mntpoint, options => '*(ro,all_squash)' };
}
sub remove {
my ($nfs_exports, $mntpoint) = @_;
my @l = grep { $_->{mntpoint} ne $mntpoint } @$nfs_exports;
@l < @$nfs_exports or ::error("not exported");
@$nfs_exports = @l;
}
sub write {
my ($nfs_exports) = @_;
foreach (@$nfs_exports) {
if (!exists $_->{raw}) {
my $mntpoint = $_->{mntpoint} =~ /\s/ ? qq("$_->{mntpoint}") : $_->{mntpoint};
$_->{raw} = sprintf("%s %s\n", $mntpoint, $_->{options});
}
}
local *F;
open F, ">/etc/exports" or die "can't write /etc/exports";
print F $_->{raw} foreach @$nfs_exports;
}
sub update_server {
if (fork) {
system('/usr/sbin/exportfs', '-r');
if (system('/sbin/pidof rpc.mountd >/dev/null') != 0 ||
system('/sbin/pidof nfsd >/dev/null') != 0) {
# trying to start the server...
system('/etc/init.d/nfs', $_) foreach 'stop', 'start';
}
exit 0;
}
}
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