diff options
Diffstat (limited to 'perl/Wallet')
| -rw-r--r-- | perl/Wallet/ACL/LDAP/Attribute.pm | 258 | ||||
| -rw-r--r-- | perl/Wallet/Config.pm | 79 | ||||
| -rw-r--r-- | perl/Wallet/Schema.pm | 2 |
3 files changed, 339 insertions, 0 deletions
diff --git a/perl/Wallet/ACL/LDAP/Attribute.pm b/perl/Wallet/ACL/LDAP/Attribute.pm new file mode 100644 index 0000000..7a54546 --- /dev/null +++ b/perl/Wallet/ACL/LDAP/Attribute.pm @@ -0,0 +1,258 @@ +# Wallet::ACL::LDAP::Attribute -- Wallet LDAP attribute ACL verifier. +# +# Written by Russ Allbery +# Copyright 2012 +# The Board of Trustees of the Leland Stanford Junior University +# +# See LICENSE for licensing terms. + +############################################################################## +# Modules and declarations +############################################################################## + +package Wallet::ACL::LDAP::Attribute; +require 5.006; + +use strict; +use vars qw(@ISA $VERSION); + +use Authen::SASL (); +use Net::LDAP qw(LDAP_COMPARE_TRUE); +use Wallet::ACL::Base; + +@ISA = qw(Wallet::ACL::Base); + +# This version should be increased on any code change to this module. Always +# use two digits for the minor version with a leading zero if necessary so +# that it will sort properly. +$VERSION = '0.01'; + +############################################################################## +# Interface +############################################################################## + +# Create a new persistant verifier. Load the Net::LDAP module and open a +# persistant LDAP server connection that we'll use for later calls. +sub new { + my $type = shift; + my $host = $Wallet::Config::LDAP_HOST; + my $base = $Wallet::Config::LDAP_BASE; + unless ($host and defined ($base) and $Wallet::Config::LDAP_CACHE) { + die "LDAP attribute ACL support not configured\n"; + } + + # Ensure the required Perl modules are available and bind to the directory + # server. Catch any errors with a try/catch block. + my $ldap; + eval { + local $ENV{KRB5CCNAME} = $Wallet::Config::LDAP_CACHE; + my $sasl = Authen::SASL->new (mechanism => 'GSSAPI'); + $ldap = Net::LDAP->new ($host, onerror => 'die'); + my $mesg = eval { $ldap->bind (undef, sasl => $sasl) }; + }; + if ($@) { + my $error = $@; + chomp $error; + 1 while ($error =~ s/ at \S+ line \d+\.?\z//); + die "LDAP attribute ACL support not available: $error\n"; + } + + # We successfully bound, so create our object and return it. + my $self = { ldap => $ldap }; + bless ($self, $type); + return $self; +} + +# Check whether a given principal has the required LDAP attribute. We first +# map the principal to a DN by doing a search for that principal (and bailing +# if we get more than one entry). Then, we do a compare to see if that DN has +# the desired attribute and value. +# +# If the ldap_map_principal sub is defined in Wallet::Config, call it on the +# principal first to map it to the value for which we'll search. +# +# The connection is configured to die on any error, so we do all the work in a +# try/catch block to report errors. +sub check { + my ($self, $principal, $acl) = @_; + undef $self->{error}; + unless ($principal) { + $self->error ('no principal specified'); + return; + } + my ($attr, $value); + if ($acl) { + ($attr, $value) = split ('=', $acl, 2); + } + unless (defined ($attr) and defined ($value)) { + $self->error ('malformed ldap-attr ACL'); + return; + } + my $ldap = $self->{ldap}; + + # Map the principal name to an attribute value for our search if we're + # doing a custom mapping. + if (defined &Wallet::Config::ldap_map_principal) { + eval { $principal = Wallet::Config::ldap_map_principal ($principal) }; + if ($@) { + $self->error ("mapping principal to LDAP failed: $@"); + return; + } + } + + # Now, map the user to a DN by doing a search. + my $entry; + eval { + my $fattr = $Wallet::Config::LDAP_FILTER_ATTR || 'krb5PrincipalName'; + my $filter = "($fattr=$principal)"; + my $base = $Wallet::Config::LDAP_BASE; + my @options = (base => $base, filter => $filter, attrs => [ 'dn' ]); + my $search = $ldap->search (@options); + if ($search->count == 1) { + $entry = $search->pop_entry; + } elsif ($search->count > 1) { + die $search->count . " LDAP entries found for $principal"; + } + }; + if ($@) { + $self->error ("cannot search for $principal in LDAP: $@"); + return; + } + return 0 unless $entry; + + # We have a user entry. We can now check whether that user has the + # desired attribute and value. + my $result; + eval { + my $mesg = $ldap->compare ($entry, attr => $attr, value => $value); + $result = $mesg->code; + }; + if ($@) { + $self->error ("cannot check LDAP attribute $attr for $principal: $@"); + return; + } + return ($result == LDAP_COMPARE_TRUE) ? 1 : 0; +} + +1; + +############################################################################## +# Documentation +############################################################################## + +=for stopwords +ACL Allbery + +=head1 NAME + +Wallet::ACL::LDAP::Attribute - Wallet ACL verifier for LDAP attribute compares + +=head1 SYNOPSIS + + my $verifier = Wallet::ACL::LDAP::Attribute->new; + my $status = $verifier->check ($principal, "$attr=$value"); + if (not defined $status) { + die "Something failed: ", $verifier->error, "\n"; + } elsif ($status) { + print "Access granted\n"; + } else { + print "Access denied\n"; + } + +=head1 DESCRIPTION + +Wallet::ACL::LDAP::Attribute checks whether the LDAP record for the entry +corresponding to a principal contains an attribute with a particular +value. It is used to verify ACL lines of type C<ldap-attr>. The value of +such an ACL is an attribute followed by an equal sign and a value, and the +ACL grants access to a given principal if and only if the LDAP entry for +that principal has that attribute set to that value. + +To use this object, several configuration parameters must be set. See +L<Wallet::Config> for details on those configuration parameters and +information about how to set wallet configuration. + +=head1 METHODS + +=item new() + +Creates a new ACL verifier. Opens and binds the connection to the LDAP +server. + +=item check(PRINCIPAL, ACL) + +Returns true if PRINCIPAL is granted access according to ACL, false if +not, and undef on an error (see L<"DIAGNOSTICS"> below). ACL must be an +attribute name and a value, separated by an equal sign (with no +whitespace). PRINCIPAL will be granted access if its LDAP entry contains +that attribute with that value. + +=item error() + +Returns the error if check() returned undef. + +=back + +=head1 DIAGNOSTICS + +The new() method may fail with one of the following exceptions: + +=item LDAP attribute ACL support not available: %s + +Attempting to connect or bind to the LDAP server failed. + +=item LDAP attribute ACL support not configured + +The required configuration parameters were not set. See Wallet::Config(3) +for the required configuration parameters and how to set them. + +=back + +Verifying an LDAP attribute ACL may fail with the following errors +(returned by the error() method): + +=over 4 + +=item cannot check LDAP attribute %s for %s: %s + +The LDAP compare to check for the required attribute failed. The +attribute may have been misspelled, or there may be LDAP directory +permission issues. This error indicates that PRINCIPAL's entry was +located in LDAP, but the check failed during the compare to verify the +attribute value. + +=item cannot search for %s in LDAP: %s + +Searching for PRINCIPAL (possibly after ldap_map_principal() mapping) +failed. This is often due to LDAP directory permissions issues. This +indicates a failure during the mapping of PRINCIPAL to an LDAP DN. + +=item malformed ldap-attr ACL + +The ACL parameter to check() was malformed. Usually this means that +either the attribute or the value were empty or the required C<=> sign +separating them was missing. + +=item mapping principal to LDAP failed: %s + +There was an ldap_map_principal() function defined in the wallet +configuration, but calling it for the PRINCIPAL argument failed. + +=item no principal specified + +The PRINCIPAL parameter to check() was undefined or the empty string. + +=back + +=head1 SEE ALSO + +Wallet::ACL(3), Wallet::ACL::Base(3), Wallet::Config(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 AUTHOR + +Russ Allbery <rra@stanford.edu> + +=cut diff --git a/perl/Wallet/Config.pm b/perl/Wallet/Config.pm index 23a051d..3f53f74 100644 --- a/perl/Wallet/Config.pm +++ b/perl/Wallet/Config.pm @@ -378,6 +378,85 @@ our $KEYTAB_REMCTL_PORT; =back +=head1 LDAP ACL CONFIGURATION + +These configuration variables are only needed if you intend to use the +C<ldap-attr> ACL type (the Wallet::ACL::LDAP::Attribute class). They +specify the LDAP server and additional connection and data model +information required for the wallet to check for the existence of +attributes. + +=over 4 + +=item LDAP_HOST + +The LDAP server name to use to verify LDAP ACLs. This variable must be +set to use LDAP ACLs. + +=cut + +our $LDAP_HOST; + +=item LDAP_BASE + +The base DN under which to search for the entry corresponding to a +principal. Currently, the wallet always does a full subtree search under +this base DN. This variable must be set to use LDAP ACLs. + +=cut + +our $LDAP_BASE; + +=item LDAP_FILTER_ATTR + +The attribute used to find the entry corresponding to a principal. The +LDAP entry containing this attribute with a value equal to the principal +will be found and checked for the required attribute and value. If this +variable is not set, the default is C<krb5PrincipalName>. + +=cut + +our $LDAP_FILTER_ATTR; + +=item LDAP_CACHE + +Specifies the Kerberos ticket cache to use when connecting to the LDAP +server. GSS-API authentication is always used; there is currently no +support for any other type of bind. The ticket cache must be for a +principal with access to verify the values of attributes that will be used +with this ACL type. This variable must be set to use LDAP ACLs. + +=cut + +our $LDAP_CACHE; + +=back + +Finally, depending on the structure of the LDAP directory being queried, +there may not be any attribute in the directory whose value exactly +matches the Kerberos principal. The attribute designated by +LDAP_FILTER_ATTR may instead hold a transformation of the principal name +(such as the principal with the local realm stripped off, or rewritten +into an LDAP DN form). If this is the case, define a Perl function named +ldap_map_attribute. This function will be called whenever an LDAP +attribute ACL is being verified. It will take one argument, the +principal, and is expected to return the value to search for in the LDAP +directory server. + +For example, if the principal name without the local realm is stored in +the C<uid> attribute in the directory, set LDAP_FILTER_ATTR to C<uid> and +then define ldap_map_attribute as follows: + + sub ldap_map_attribute { + my ($principal) = @_; + $principal =~ s/\@EXAMPLE\.COM$//; + return $principal; + } + +Note that this example only removes the local realm (here, EXAMPLE.COM). +Any principal from some other realm will be left fully qualified, and then +presumably will not be found in the directory. + =head1 NETDB ACL CONFIGURATION These configuration variables are only needed if you intend to use the diff --git a/perl/Wallet/Schema.pm b/perl/Wallet/Schema.pm index 7400776..5c6b9ca 100644 --- a/perl/Wallet/Schema.pm +++ b/perl/Wallet/Schema.pm @@ -277,6 +277,8 @@ Holds the supported ACL schemes and their corresponding Perl classes: insert into acl_schemes (as_name, as_class) values ('krb5-regex', 'Wallet::ACL::Krb5::Regex'); insert into acl_schemes (as_name, as_class) + values ('ldap-attr', 'Wallet::ACL::LDAP::Attribute'); + insert into acl_schemes (as_name, as_class) values ('netdb', 'Wallet::ACL::NetDB'); insert into acl_schemes (as_name, as_class) values ('netdb-root', 'Wallet::ACL::NetDB::Root'); |