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# Wallet::Kadmin::MIT -- Wallet Kerberos administration API for MIT.
#
# Written by Russ Allbery <rra@stanford.edu>
# Pulled into a module by Jon Robertson <jonrober@stanford.edu>
# Copyright 2007, 2008, 2009, 2010
# Board of Trustees, Leland Stanford Jr. University
#
# See LICENSE for licensing terms.
##############################################################################
# Modules and declarations
##############################################################################
package Wallet::Kadmin::MIT;
require 5.006;
use strict;
use vars qw(@ISA $VERSION);
use Wallet::Config ();
use Wallet::Kadmin ();
@ISA = qw(Wallet::Kadmin);
# This version should be increased on any code change to this module. Always
# use two digits for the minor version with a leading zero if necessary so
# that it will sort properly.
$VERSION = '0.02';
##############################################################################
# kadmin Interaction
##############################################################################
# Make sure that principals are well-formed and don't contain characters that
# will cause us problems when talking to kadmin. Takes a principal and
# returns true if it's okay, false otherwise. Note that we do not permit
# realm information here.
sub valid_principal {
my ($self, $principal) = @_;
return scalar ($principal =~ m,^[\w-]+(/[\w_.-]+)?\z,);
}
# Run a kadmin command and capture the output. Returns the output, either as
# a list of lines or, in scalar context, as one string. The exit status of
# kadmin is often worthless.
sub kadmin {
my ($self, $command) = @_;
unless (defined ($Wallet::Config::KEYTAB_PRINCIPAL)
and defined ($Wallet::Config::KEYTAB_FILE)
and defined ($Wallet::Config::KEYTAB_REALM)) {
die "keytab object implementation not configured\n";
}
my @args = ('-p', $Wallet::Config::KEYTAB_PRINCIPAL, '-k', '-t',
$Wallet::Config::KEYTAB_FILE, '-q', $command);
push (@args, '-s', $Wallet::Config::KEYTAB_HOST)
if $Wallet::Config::KEYTAB_HOST;
push (@args, '-r', $Wallet::Config::KEYTAB_REALM)
if $Wallet::Config::KEYTAB_REALM;
my $pid = open (KADMIN, '-|');
if (not defined $pid) {
$self->error ("cannot fork: $!");
return;
} elsif ($pid == 0) {
$self->{fork_callback} () if $self->{fork_callback};
unless (open (STDERR, '>&STDOUT')) {
warn "wallet: cannot dup stdout: $!\n";
exit 1;
}
unless (exec ($Wallet::Config::KEYTAB_KADMIN, @args)) {
warn "wallet: cannot run $Wallet::Config::KEYTAB_KADMIN: $!\n";
exit 1;
}
}
local $_;
my @output;
while (<KADMIN>) {
if (/^wallet: cannot /) {
s/^wallet: //;
$self->error ($_);
return;
}
push (@output, $_) unless /Authenticating as principal/;
}
close KADMIN;
return wantarray ? @output : join ('', @output);
}
##############################################################################
# Public interfaces
##############################################################################
# Set a callback to be called for forked kadmin processes.
sub fork_callback {
my ($self, $callback) = @_;
$self->{fork_callback} = $callback;
}
# Check whether a given principal already exists in Kerberos. Returns true if
# so, false otherwise. Returns undef if kadmin fails, with the error already
# set by kadmin.
sub exists {
my ($self, $principal) = @_;
return unless $self->valid_principal ($principal);
if ($Wallet::Config::KEYTAB_REALM) {
$principal .= '@' . $Wallet::Config::KEYTAB_REALM;
}
my $output = $self->kadmin ("getprinc $principal");
if (!defined $output) {
return;
} elsif ($output =~ /^get_principal: /) {
return 0;
} else {
return 1;
}
}
# Create a principal in Kerberos. Sets the error and returns undef on failure,
# and returns 1 on either success or the principal already existing.
sub addprinc {
my ($self, $principal) = @_;
unless ($self->valid_principal ($principal)) {
$self->error ("invalid principal name $principal");
return;
}
return 1 if $self->exists ($principal);
if ($Wallet::Config::KEYTAB_REALM) {
$principal .= '@' . $Wallet::Config::KEYTAB_REALM;
}
my $flags = $Wallet::Config::KEYTAB_FLAGS || '';
my $output = $self->kadmin ("addprinc -randkey $flags $principal");
if (!defined $output) {
return;
} elsif ($output =~ /^add_principal: (.*)/m) {
$self->error ("error adding principal $principal: $1");
return;
}
return 1;
}
# Create a keytab from a principal. Takes the principal, the file, and
# optionally a list of encryption types to which to limit the keytab. Return
# true if successful, false otherwise. If the keytab creation fails, sets the
# error.
sub ktadd {
my ($self, $principal, $file, @enctypes) = @_;
unless ($self->valid_principal ($principal)) {
$self->error ("invalid principal name: $principal");
return;
}
if ($Wallet::Config::KEYTAB_REALM) {
$principal .= '@' . $Wallet::Config::KEYTAB_REALM;
}
my $command = "ktadd -q -k $file";
if (@enctypes) {
@enctypes = map { /:/ ? $_ : "$_:normal" } @enctypes;
$command .= ' -e "' . join (' ', @enctypes) . '"';
}
my $output = $self->kadmin ("$command $principal");
if (!defined $output) {
return;
} elsif ($output =~ /^(?:kadmin|ktadd): (.*)/m) {
$self->error ("error creating keytab for $principal: $1");
return;
}
return 1;
}
# Delete a principal from Kerberos. Return true if successful, false
# otherwise. If the deletion fails, sets the error. If the principal doesn't
# exist, return success; we're bringing reality in line with our expectations.
sub delprinc {
my ($self, $principal) = @_;
unless ($self->valid_principal ($principal)) {
$self->error ("invalid principal name: $principal");
}
my $exists = $self->exists ($principal);
if (!defined $exists) {
return;
} elsif (not $exists) {
return 1;
}
if ($Wallet::Config::KEYTAB_REALM) {
$principal .= '@' . $Wallet::Config::KEYTAB_REALM;
}
my $output = $self->kadmin ("delprinc -force $principal");
if (!defined $output) {
return;
} elsif ($output =~ /^delete_principal: (.*)/m) {
$self->error ("error deleting $principal: $1");
return;
}
return 1;
}
# Create a new MIT kadmin object. Very empty for the moment, but later it
# will probably fill out if we go to using a module rather than calling
# kadmin directly.
sub new {
my ($class) = @_;
my $self = {};
bless ($self, $class);
return $self;
}
1;
__END__
##############################################################################
# Documentation
##############################################################################
=for stopwords
keytabs keytab kadmin KDC API Allbery
=head1 NAME
Wallet::Kadmin::MIT - Wallet Kerberos administration API for MIT
=head1 SYNOPSIS
my $kadmin = Wallet::Kadmin::MIT->new;
$kadmin->addprinc ("host/shell.example.com");
$kadmin->ktadd ("host/shell.example.com", "aes256-cts-hmac-sha1-96");
my $exists = $kadmin->exists ("host/oldshell.example.com");
$kadmin->delprinc ("host/oldshell.example.com") if $exists;
=head1 DESCRIPTION
Wallet::Kadmin::MIT implements the Wallet::Kadmin API for MIT Kerberos,
providing an interface to create and delete principals and create keytabs.
It provides the API documented in Wallet::Kadmin(3) for an MIT Kerberos
KDC.
To use this object, several configuration parameters must be set. See
Wallet::Config(3) for details on those configuration parameters and
information about how to set wallet configuration.
=head1 LIMITATIONS
Currently, this implementation calls an external B<kadmin> program rather
than using a native Perl module and therefore requires B<kadmin> be
installed and parses its output. It may miss some error conditions if the
output of B<kadmin> ever changes.
=head1 SEE ALSO
kadmin(8), Wallet::Config(3), Wallet::Kadmin(3),
Wallet::Object::Keytab(3), wallet-backend(8)
This module is part of the wallet system. The current version is
available from L<http://www.eyrie.org/~eagle/software/wallet/>.
=head1 AUTHORS
Russ Allbery <rra@stanford.edu> and Jon Robertson <jonrober@stanford.edu>.
=cut
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