# Wallet::Config -- Configuration handling for the wallet server. # $Id$ # # Written by Russ Allbery # Copyright 2007, 2008 Board of Trustees, Leland Stanford Jr. University # # See LICENSE for licensing terms. package Wallet::Config; require 5.006; use strict; use vars qw($PATH $VERSION); # 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'; # Path to the config file to load. $PATH = '/etc/wallet/wallet.conf'; =head1 NAME Wallet::Config - Configuration handling for the wallet server =head1 SYNOPSIS use Wallet::Config; my $driver = $Wallet::Config::DB_DRIVER; my $info; if (defined $Wallet::Config::DB_INFO) { $info = $Wallet::Config::DB_INFO; } else { $info = "database=$Wallet::Config::DB_NAME"; $info .= ";host=$Wallet::Config::DB_HOST" if $Wallet::Config::DB_HOST; $info .= ";port=$Wallet::Config::DB_PORT" if $Wallet::Config::DB_PORT; } my $dsn = "dbi:$driver:$info"; my $user = $Wallet::Config::DB_USER; my $password = $Wallet::Config::DB_PASSWORD; my $dbh = DBI->connect ($dsn, $user, $password); =head1 DESCRIPTION Wallet::Config encapsulates all of the site-specific configuration for the wallet server. It is implemented as a Perl class that declares and sets the defaults for various configuration variables and then, if it exists, loads the file F. That file should contain any site-specific overrides to the defaults, and at least some parameters must be set. This file must be valid Perl. To set a variable, use the syntax: $VARIABLE = ; where VARIABLE is the variable name (always in all-capital letters) and is the value. If setting a variable to a string and not a number, you should normally enclose in C<''>. For example, to set the variable DB_DRIVER to C, use: $DB_DRIVER = 'MySQL'; Always remember the initial dollar sign (C<$>) and ending semicolon (C<;>). Those familiar with Perl syntax can of course use the full range of Perl expressions. This configuration file should end with the line: 1; This ensures that Perl doesn't think there is an error when loading the file. =head1 DATABASE CONFIGURATION =over 4 =item DB_DRIVER Sets the Perl database driver to use for the wallet database. Common values would be C or C. Less common values would be C, C, or C. The appropriate DBD::* Perl module for the chosen driver must be installed and will be dynamically loaded by the wallet. For more information, see DBI(3). This variable must be set. =cut our $DB_DRIVER; =item DB_INFO Sets the remaining contents for the DBI DSN (everything after the driver). Using this variable provides full control over the connect string passed to DBI. When using SQLite, set this variable to the path to the SQLite database. If this variable is set, DB_NAME, DB_HOST, and DB_PORT are ignored. For more information, see DBI(3) and the documentation for the database driver you're using. Either DB_INFO or DB_NAME must be set. If you don't need to pass any additional information to DBI, set DB_INFO to the empty string (C<''>). =cut our $DB_INFO; =item DB_NAME If DB_INFO is not set, specifies the database name. The third part of the DBI connect string will be set to C, possibly with a host and port appended if DB_HOST and DB_PORT are set. For more information, see DBI(3) and the documentation for the database driver you're using. Either DB_INFO or DB_NAME must be set. =cut our $DB_NAME; =item DB_HOST If DB_INFO is not set, specifies the database host. C<;host=DB_HOST> will be appended to the DBI connect string. For more information, see DBI(3) and the documentation for the database driver you're using. =cut our $DB_HOST; =item DB_PORT If DB_PORT is not set, specifies the database port. C<;port=DB_PORT> will be appended to the DBI connect string. If this variable is set, DB_HOST should also be set. For more information, see DBI(3) and the documentation for the database driver you're using. =cut our $DB_PORT; =item DB_USER Specifies the user for database authentication. Some database backends, particularly SQLite, do not need this. =cut our $DB_USER; =item DB_PASSWORD Specifies the password for database authentication. Some database backends, particularly SQLite, do not need this. =cut our $DB_PASSWORD; =back =head1 KEYTAB OBJECT CONFIGURATION These configuration variables only need to be set if you intend to use the C object type (the Wallet::Object::Keytab class). They point the keytab object implementation at the right Kerberos server and B client. =over 4 =item KEYTAB_FILE Specifies the keytab to use to authenticate to B. The principal whose key is stored in this keytab must have the ability to create, modify, inspect, and delete any principals that should be managed by the wallet. (In MIT Kerberos F parlance, this is C privileges.) KEYTAB_FILE must be set to use keytab objects. =cut our $KEYTAB_FILE; =item KEYTAB_FLAGS These flags, if any, are passed to the C command when creating a new principal in the Kerberos KDC. To not pass any flags, set KEYTAB_FLAGS to the empty string. The default value is C<-clearpolicy>, which clears any password strength policy from principals created by the wallet. (Since the wallet randomizes the keys, password strength checking is generally pointless and may interact poorly with the way C works when third-party add-ons for password strength checking are used.) =cut our $KEYTAB_FLAGS = '-clearpolicy'; =item KEYTAB_HOST Specifies the host on which the kadmin service is running. This setting overrides the C setting in the [realms] section of F and any DNS SRV records and allows the wallet to run on a system that doesn't have a Kerberos configuration for the wallet's realm. =cut our $KEYTAB_HOST; =item KEYTAB_KADMIN The path to the B command-line client. The default value is C, which will cause the wallet to search for B on its default PATH. =cut our $KEYTAB_KADMIN = 'kadmin'; =item KEYTAB_PRINCIPAL The principal whose key is stored in KEYTAB_FILE. The wallet will authenticate as this principal to the kadmin service. KEYTAB_PRINCIPAL must be set to use keytab objects, at least until B is smart enough to use the first principal found in the keytab it's using for authentication. =cut our $KEYTAB_PRINCIPAL; =item KEYTAB_REALM Specifies the realm in which to create Kerberos principals. The keytab object implementation can only work in a single realm for a given wallet installation and the keytab object names are stored without realm. KEYTAB_REALM is added when talking to the KDC via B. KEYTAB_REALM must be set to use keytab objects. C doesn't always default to the local realm. =cut our $KEYTAB_REALM; =item KEYTAB_TMP A directory into which the wallet can write keytabs temporarily while processing C commands from clients. The keytabs are written into this directory with predictable names, so this should not be a system temporary directory such as F or F. It's best to create a directory solely for this purpose that's owned by the user the wallet server will run as. KEYTAB_TMP must be set to use keytab objects. =cut our $KEYTAB_TMP; =back =head2 Retrieving Existing Keytabs The keytab object backend optionally supports retrieving existing keys, and hence keytabs, for Kerberos principals by contacting the KDC via remctl and talking to B. This is enabled by setting the C flag on keytab objects. To configure that support, set the following variables. =over 4 =item KEYTAB_REMCTL_CACHE Specifies the ticket cache to use when retrieving existing keytabs from the KDC. This is only used to implement support for the C flag. The ticket cache must be for a principal with access to run C via remctl on KEYTAB_REMCTL_HOST. =cut our $KEYTAB_REMCTL_CACHE; =item KEYTAB_REMCTL_HOST The host to which to connect with remctl to retrieve existing keytabs. This is only used to implement support for the C flag. This host must provide the C command and KEYTAB_REMCTL_CACHE must also be set to a ticket cache for a principal with access to run that command. =cut our $KEYTAB_REMCTL_HOST; =item KEYTAB_REMCTL_PRINCIPAL The service principal to which to authenticate when retrieving existing keytabs. This is only used to implement support for the C flag. If this variable is not set, the default is formed by prepending C to KEYTAB_REMCTL_HOST. (Note that KEYTAB_REMCTL_HOST is not lowercased first.) =cut our $KEYTAB_REMCTL_PRINCIPAL; =item KEYTAB_REMCTL_PORT The port on KEYTAB_REMCTL_HOST to which to connect with remctl to retrieve existing keytabs. This is only used to implement support for the C flag. If this variable is not set, the default remctl port will be used. =cut our $KEYTAB_REMCTL_PORT; =back =head2 Synchronization with AFS kaserver The keytab backend optionally supports synchronizing keys between the Kerberos v5 realm and a Kerberos v4 realm using kaserver. This synchronization is done using B and is controlled by the C attribute on keytab objects. To configure that support, set the following variables. =over 4 =item KEYTAB_AFS_ADMIN The Kerberos v4 principal to use for authentication to the AFS kaserver. If this principal is not in the default local Kerberos v4 realm, it must be fully qualified. A srvtab for this principal must be stored in the path set in $KEYTAB_AFS_SRVTAB. This principal must have the ADMIN flag set in the AFS kaserver so that it can create and remove principals. This variable must be set to use the kaserver synchronization support. =cut our $KEYTAB_AFS_ADMIN; =item KEYTAB_AFS_DESTROY If this variable, which is false by default, is set to a true value, each time a keytab object that is not configured to be synchronized with the AFS kaserver, the corresponding Kerberos v4 principal will be deleted from the AFS kaserver. Use this with caution; it will cause the AFS kaserver realm to be slowly stripped of principals. This is intended for use with migration from Kerberos v4 to Kerberos v5, where the old principals should be deleted out of Kerberos v4 whenever not requested from the wallet to aid in tracking down and removing any systems with lingering Kerberos v4 dependencies. Be aware that multiple Kerberos v5 principals map to the same Kerberos v4 principal since in Kerberos v4 the domain name is stripped from the principal for machine principals. If you create a keytab named host/foo.example.com and mark it synchronized, and then create another keytab named host/foo.example.net and don't mark it synchronized, downloading the second will destroy the Kerberos v4 principal of the first if this variable is set. =cut our $KEYTAB_AFS_DESTROY; =item KEYTAB_AFS_KASETKEY The path to the B command-line client. The default value is C, which will cause the wallet to search for B on its default PATH. =cut our $KEYTAB_AFS_KASETKEY = 'kasetkey'; =item KEYTAB_AFS_REALM The name of the Kerberos v4 realm with which to synchronize keys. This is a realm, not a cell, so it should be in all uppercase. If this variable is not set, the default is the realm determined from the local cell name. =cut our $KEYTAB_AFS_REALM; =item KEYTAB_AFS_SRVTAB The path to a srvtab used to authenticate to the AFS kaserver. This srvtab should be for the principal set in $KEYTAB_AFS_ADMIN. This variable must be set to use the kaserver synchronization support. =cut our $KEYTAB_AFS_SRVTAB; =back =head1 NETDB ACL CONFIGURATION These configuration variables are only needed if you intend to use the C ACL type (the Wallet::ACL::NetDB class). They specify the remctl connection information for retrieving user roles from NetDB and the local realm to remove from principals (since NetDB normally expects unscoped local usernames). =over 4 =item NETDB_REALM The wallet uses fully-qualified principal names (including the realm), but NetDB normally expects local usernames without the realm. If this variable is set, the given realm will be stripped from any principal names before passing them to NetDB. Principals in other realms will be passed to NetDB without modification. =cut our $NETDB_REALM; =item NETDB_REMCTL_CACHE Specifies the ticket cache to use when querying the NetDB remctl interface for user roles. The ticket cache must be for a principal with access to run C via remctl on KEYTAB_REMCTL_HOST. This variable must be set to use NetDB ACLs. =cut our $NETDB_REMCTL_CACHE; =item NETDB_REMCTL_HOST The host to which to connect with remctl to query NetDB for user roles. This host must provide the C command and NETDB_REMCTL_CACHE must also be set to a ticket cache for a principal with access to run that command. This variable must be set to use NetDB ACLs. =cut our $NETDB_REMCTL_HOST; =item NETDB_REMCTL_PRINCIPAL The service principal to which to authenticate when querying NetDB for user roles. If this variable is not set, the default is formed by prepending C to NETDB_REMCTL_HOST. (Note that NETDB_REMCTL_HOST is not lowercased first.) =cut our $NETDB_REMCTL_PRINCIPAL; =item NETDB_REMCTL_PORT The port on NETDB_REMCTL_HOST to which to connect with remctl to query NetDB for user roles. If this variable is not set, the default remctl port will be used. =cut our $NETDB_REMCTL_PORT; =back =head1 DEFAULT OWNERS By default, only users in the ADMIN ACL can create new objects in the wallet. To allow other users to create new objects, define a Perl function named default_owner. This function will be called whenever a non-ADMIN user tries to create a new object and will be passed the type and name of the object. It should return undef if there is no default owner for that object. If there is, it should return a list containing the name to use for the ACL and then zero or more anonymous arrays of two elements each giving the type and identifier for each ACL entry. For example, the following simple function says to use a default owner named C with one entry of type C and identifier C for the object with type C and name C: sub default_owner { my ($type, $name) = @_; if ($type eq 'keytab' and $name eq 'host/example.com') { return ('default', [ 'krb5', 'rra@example.com' ]); } else { return; } } Of course, normally this function is used for more complex mappings. Here is a more complete example. For objects of type keytab corresponding to various types of per-machine principals, return a default owner that sets as owner anyone with a NetDB role for that system and the system's host principal. This permits authorization management using NetDB while also allowing the system to bootstrap itself once the host principal has been downloaded and rekey itself using the old host principal. sub default_owner { my ($type, $name) = @_; my %allowed = map { $_ => 1 } qw(HTTP cifs host imap ldap nfs pop sieve smtp webauth); my $realm = 'example.com'; return unless $type eq 'keytab'; return unless $name =~ m%/%; my ($service, $instance) = split ('/', $name, 2); return unless $allowed{$service}; my $acl_name = "host/$instance"; my @acl = ([ 'netdb', $instance ], [ 'krb5', "host/$instance\@$realm" ]); return ($acl_name, @acl); } The auto-created ACL used for the owner of the new object will, in the above example, be named C> where I is the fully-qualified name of the system as derived from the keytab being requested. If the name of the ACL returned by the default_owner function matches an ACL that already exists in the wallet database, the existing ACL will be compared to the default ACL returned by the default_owner function. If the existing ACL has the same entries as the one returned by default_owner, creation continues if the user is authorized by that ACL. If they don't match, creation of the object is rejected, since the presence of an existing ACL may indicate that something different is being done with this object. =head1 NAMING ENFORCEMENT By default, wallet permits administrators to create objects of any name (unless the object backend rejects the name). However, naming standards for objects can be enforced, even for administrators, by defining a Perl function in the configuration file named verify_name. If such a function exists, it will be called for any object creation and given the type of object, the object name, and the identity of the person doing the creation. If it returns undef or the empty string, object creation will be allowed. If it returns anything else, object creation is rejected and the return value is used as the error message. Please note that this return status is backwards from what one would normally expect. A false value is success; a true value is failure with an error message. For example, the following verify_name function would ensure that any keytab objects for particular principals have fully-qualified hostnames: sub verify_name { my ($type, $name, $user) = @_; my %host_based = map { $_ => 1 } qw(HTTP cifs host imap ldap nfs pop sieve smtp webauth); return unless $type eq 'keytab'; return unless $name =~ m%/%; my ($service, $instance) = split ('/', $name, 2); return unless $host_based{$service}; return "host name $instance must be fully qualified" unless $instance =~ /\./; return; } Objects that aren't of type C or which aren't for a host-based key have no naming requirements enforced. =cut # Now, load the configuration file so that it can override the defaults. if (-r $PATH) { do $PATH or die (($@ || $!) . "\n"); } 1; __END__ =head1 SEE ALSO DBI(3), Wallet::Object::Keytab(3), Wallet::Server(3), wallet-backend(8) This module is part of the wallet system. The current version is available from L. =head1 AUTHOR Russ Allbery =cut