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# -*- mode: perl -*-
# ============================================================================
package Net::SNMP::Security::USM;
# $Id: USM.pm,v 4.1 2010/09/10 00:01:22 dtown Rel $
# Object that implements the SNMPv3 User-based Security Model.
# Copyright (c) 2001-2010 David M. Town <dtown@cpan.org>
# All rights reserved.
# This program is free software; you may redistribute it and/or modify it
# under the same terms as the Perl 5 programming language system itself.
# ============================================================================
use strict;
use Net::SNMP::Security qw( :ALL );
use Net::SNMP::Message qw(
:msgFlags asn1_itoa OCTET_STRING SEQUENCE INTEGER SNMP_VERSION_3 TRUE FALSE
);
use Crypt::DES();
use Digest::MD5();
use Digest::SHA1();
use Digest::HMAC();
## Version of the Net::SNMP::Security::USM module
our $VERSION = v4.0.1;
## Handle importing/exporting of symbols
use base qw( Net::SNMP::Security );
our @EXPORT_OK;
our %EXPORT_TAGS = (
authprotos => [
qw( AUTH_PROTOCOL_NONE AUTH_PROTOCOL_HMACMD5 AUTH_PROTOCOL_HMACSHA )
],
levels => [
qw( SECURITY_LEVEL_NOAUTHNOPRIV SECURITY_LEVEL_AUTHNOPRIV
SECURITY_LEVEL_AUTHPRIV )
],
models => [
qw( SECURITY_MODEL_ANY SECURITY_MODEL_SNMPV1 SECURITY_MODEL_SNMPV2C
SECURITY_MODEL_USM )
],
privprotos => [
qw( PRIV_PROTOCOL_NONE PRIV_PROTOCOL_DES PRIV_PROTOCOL_AESCFB128
PRIV_PROTOCOL_DRAFT_3DESEDE PRIV_PROTOCOL_DRAFT_AESCFB128
PRIV_PROTOCOL_DRAFT_AESCFB192 PRIV_PROTOCOL_DRAFT_AESCFB256 )
],
);
Exporter::export_ok_tags( qw( authprotos levels models privprotos ) );
$EXPORT_TAGS{ALL} = [ @EXPORT_OK ];
## RCC 3414 - Authentication protocols
sub AUTH_PROTOCOL_NONE { '1.3.6.1.6.3.10.1.1.1' } # usmNoAuthProtocol
sub AUTH_PROTOCOL_HMACMD5 { '1.3.6.1.6.3.10.1.1.2' } # usmHMACMD5AuthProtocol
sub AUTH_PROTOCOL_HMACSHA { '1.3.6.1.6.3.10.1.1.3' } # usmHMACSHAAuthProtocol
## RFC 3414 - Privacy protocols
sub PRIV_PROTOCOL_NONE { '1.3.6.1.6.3.10.1.2.1' } # usmNoPrivProtocol
sub PRIV_PROTOCOL_DES { '1.3.6.1.6.3.10.1.2.2' } # usmDESPrivProtocol
## RFC 3826 - The AES Cipher Algorithm in the SNMP USM
# usmAesCfb128Protocol
sub PRIV_PROTOCOL_AESCFB128 { '1.3.6.1.6.3.10.1.2.4' }
# The privacy protocols below have been implemented using the draft
# specifications intended to extend the User-based Security Model
# defined in RFC 3414. Since the object definitions have not been
# standardized, they have been based on the Extended Security Options
# Consortium MIB found at http://www.snmp.com/eso/esoConsortiumMIB.txt.
# Extension to Support Triple-DES EDE <draft-reeder-snmpv3-usm-3desede-00.txt>
# Reeder and Gudmunsson; October 1999, expired April 2000
# usm3DESPrivProtocol
sub PRIV_PROTOCOL_DRAFT_3DESEDE { '1.3.6.1.4.1.14832.1.1' }
# AES Cipher Algorithm in the USM <draft-blumenthal-aes-usm-04.txt>
# Blumenthal, Maino, and McCloghrie; October 2002, expired April 2003
# usmAESCfb128PrivProtocol
sub PRIV_PROTOCOL_DRAFT_AESCFB128 { '1.3.6.1.4.1.14832.1.2' }
# usmAESCfb192PrivProtocol
sub PRIV_PROTOCOL_DRAFT_AESCFB192 { '1.3.6.1.4.1.14832.1.3' }
# usmAESCfb256PrivProtocol
sub PRIV_PROTOCOL_DRAFT_AESCFB256 { '1.3.6.1.4.1.14832.1.4' }
## Package variables
our $ENGINE_ID; # Our authoritative snmpEngineID
# [public methods] -----------------------------------------------------------
sub new
{
my ($class, %argv) = @_;
# Create a new data structure for the object
my $this = bless {
'_error' => undef, # Error message
'_version' => SNMP_VERSION_3, # version
'_authoritative' => FALSE, # Authoritative flag
'_discovered' => FALSE, # Engine discovery flag
'_synchronized' => FALSE, # Synchronization flag
'_engine_id' => q{}, # snmpEngineID
'_engine_boots' => 0, # snmpEngineBoots
'_engine_time' => 0, # snmpEngineTime
'_latest_engine_time' => 0, # latestReceivedEngineTime
'_time_epoc' => time(), # snmpEngineBoots epoc
'_user_name' => q{}, # securityName
'_auth_data' => undef, # Authentication data
'_auth_key' => undef, # authKey
'_auth_password' => undef, # Authentication password
'_auth_protocol' => AUTH_PROTOCOL_HMACMD5, # authProtocol
'_priv_data' => undef, # Privacy data
'_priv_key' => undef, # privKey
'_priv_password' => undef, # Privacy password
'_priv_protocol' => PRIV_PROTOCOL_DES, # privProtocol
'_security_level' => SECURITY_LEVEL_NOAUTHNOPRIV
}, $class;
# We first need to find out if we are an authoritative SNMP
# engine and set the authProtocol and privProtocol if they
# have been provided.
foreach (keys %argv) {
if (/^-?authoritative$/i) {
$this->{_authoritative} = (delete $argv{$_}) ? TRUE : FALSE;
} elsif (/^-?authprotocol$/i) {
$this->_auth_protocol(delete $argv{$_});
} elsif (/^-?privprotocol$/i) {
$this->_priv_protocol(delete $argv{$_});
}
if (defined $this->{_error}) {
return wantarray ? (undef, $this->{_error}) : undef;
}
}
# Now validate the rest of the passed arguments
for (keys %argv) {
if (/^-?version$/i) {
$this->_version($argv{$_});
} elsif (/^-?debug$/i) {
$this->debug($argv{$_});
} elsif ((/^-?engineid$/i) && ($this->{_authoritative})) {
$this->_engine_id($argv{$_});
} elsif (/^-?username$/i) {
$this->_user_name($argv{$_});
} elsif (/^-?authkey$/i) {
$this->_auth_key($argv{$_});
} elsif (/^-?authpassword$/i) {
$this->_auth_password($argv{$_});
} elsif (/^-?privkey$/i) {
$this->_priv_key($argv{$_});
} elsif (/^-?privpassword$/i) {
$this->_priv_password($argv{$_});
} else {
$this->_error('The argument "%s" is unknown', $_);
}
if (defined $this->{_error}) {
return wantarray ? (undef, $this->{_error}) : undef;
}
}
# Generate a snmpEngineID and populate the object accordingly
# if we are an authoritative snmpEngine.
if ($this->{_authoritative}) {
$this->_snmp_engine_init();
}
# Define the securityParameters
if (!defined $this->_security_params()) {
return wantarray ? (undef, $this->{_error}) : undef;
}
# Return the object and an empty error message (in list context)
return wantarray ? ($this, q{}) : $this;
}
sub generate_request_msg
{
my ($this, $pdu, $msg) = @_;
# Clear any previous errors
$this->_error_clear();
if (@_ < 3) {
return $this->_error('The required PDU and/or Message object is missing');
}
# Validate the SNMP version of the PDU
if ($pdu->version() != $this->{_version}) {
return $this->_error(
'The SNMP version %d was expected, but %d was found',
$this->{_version}, $pdu->version()
);
}
# Validate the securityLevel of the PDU
if ($pdu->security_level() > $this->{_security_level}) {
return $this->_error(
'The PDU securityLevel %d is greater than the configured value %d',
$pdu->security_level(), $this->{_security_level}
);
}
# Validate PDU type with snmpEngine type
if ($pdu->expect_response()) {
if ($this->{_authoritative}) {
return $this->_error(
'Must be a non-authoritative SNMP engine to generate a %s',
asn1_itoa($pdu->pdu_type())
);
}
} else {
if (!$this->{_authoritative}) {
return $this->_error(
'Must be an authoritative SNMP engine to generate a %s',
asn1_itoa($pdu->pdu_type())
);
}
}
# Extract the msgGlobalData out of the message
my $msg_global_data = $msg->clear();
# AES in the USM Section 3.1.2.1 - "The 128-bit IV is obtained as
# the concatenation of the... ...snmpEngineBoots, ...snmpEngineTime,
# and a local 64-bit integer. We store the current snmpEngineBoots
# and snmpEngineTime before encrypting the PDU so that the computed
# IV matches the transmitted msgAuthoritativeEngineBoots and
# msgAuthoritativeEngineTime.
my $msg_engine_time = $this->_engine_time();
my $msg_engine_boots = $this->_engine_boots();
# Copy the PDU into a "plain text" buffer
my $pdu_buffer = $pdu->copy();
my $priv_params = q{};
# encryptedPDU::=OCTET STRING
if ($pdu->security_level() > SECURITY_LEVEL_AUTHNOPRIV) {
if (!defined $this->_encrypt_data($msg, $priv_params, $pdu_buffer)) {
return $this->_error();
}
}
# msgPrivacyParameters::=OCTET STRING
if (!defined $msg->prepare(OCTET_STRING, $priv_params)) {
return $this->_error($msg->error());
}
# msgAuthenticationParameters::=OCTET STRING
my $auth_params = q{};
my $auth_location = 0;
if ($pdu->security_level() > SECURITY_LEVEL_NOAUTHNOPRIV) {
# Save the location to fill in msgAuthenticationParameters later
$auth_location = $msg->length() + 12 + length $pdu_buffer;
# Set the msgAuthenticationParameters to all zeros
$auth_params = pack 'x12';
}
if (!defined $msg->prepare(OCTET_STRING, $auth_params)) {
return $this->_error($msg->error());
}
# msgUserName::=OCTET STRING
if (!defined $msg->prepare(OCTET_STRING, $pdu->security_name())) {
return $this->_error($msg->error());
}
# msgAuthoritativeEngineTime::=INTEGER
if (!defined $msg->prepare(INTEGER, $msg_engine_time)) {
return $this->_error($msg->error());
}
# msgAuthoritativeEngineBoots::=INTEGER
if (!defined $msg->prepare(INTEGER, $msg_engine_boots)) {
return $this->_error($msg->error());
}
# msgAuthoritativeEngineID
if (!defined $msg->prepare(OCTET_STRING, $this->_engine_id())) {
return $this->_error($msg->error());
}
# UsmSecurityParameters::= SEQUENCE
if (!defined $msg->prepare(SEQUENCE)) {
return $this->_error($msg->error());
}
# msgSecurityParameters::=OCTET STRING
if (!defined $msg->prepare(OCTET_STRING, $msg->clear())) {
return $this->_error($msg->error());
}
# Append the PDU
if (!defined $msg->append($pdu_buffer)) {
return $this->_error($msg->error());
}
# Prepend the msgGlobalData
if (!defined $msg->prepend($msg_global_data)) {
return $this->_error($msg->error());
}
# version::=INTEGER
if (!defined $msg->prepare(INTEGER, $this->{_version})) {
return $this->_error($msg->error());
}
# message::=SEQUENCE
if (!defined $msg->prepare(SEQUENCE)) {
return $this->_error($msg->error());
}
# Apply authentication
if ($pdu->security_level() > SECURITY_LEVEL_NOAUTHNOPRIV) {
if (!defined $this->_authenticate_outgoing_msg($msg, $auth_location)) {
return $this->_error($msg->error());
}
}
# Return the Message
return $msg;
}
sub process_incoming_msg
{
my ($this, $msg) = @_;
# Clear any previous errors
$this->_error_clear();
return $this->_error('The required Message object is missing') if (@_ < 2);
# msgSecurityParameters::=OCTET STRING
my $msg_params = $msg->process(OCTET_STRING);
return $this->_error($msg->error()) if !defined $msg_params;
# Need to move the buffer index back to the begining of the data
# portion of the OCTET STRING that contains the msgSecurityParameters.
$msg->index($msg->index() - length $msg_params);
# UsmSecurityParameters::=SEQUENCE
return $this->_error($msg->error()) if !defined $msg->process(SEQUENCE);
# msgAuthoritativeEngineID::=OCTET STRING
my $msg_engine_id;
if (!defined($msg_engine_id = $msg->process(OCTET_STRING))) {
return $this->_error($msg->error());
}
# msgAuthoritativeEngineBoots::=INTEGER (0..2147483647)
my $msg_engine_boots;
if (!defined ($msg_engine_boots = $msg->process(INTEGER))) {
return $this->_error($msg->error());
}
if (($msg_engine_boots < 0) || ($msg_engine_boots > 2147483647)) {
return $this->_error(
'The msgAuthoritativeEngineBoots value %d is out of range ' .
'(0..2147483647)', $msg_engine_boots
);
}
# msgAuthoritativeEngineTime::=INTEGER (0..2147483647)
my $msg_engine_time;
if (!defined ($msg_engine_time = $msg->process(INTEGER))) {
return $this->_error($msg->error());
}
if (($msg_engine_time < 0) || ($msg_engine_time > 2147483647)) {
return $this->_error(
'The msgAuthoritativeEngineTime value %d is out of range ' .
'(0..2147483647)', $msg_engine_time
);
}
# msgUserName::=OCTET STRING (SIZE(0..32))
if (!defined $msg->security_name($msg->process(OCTET_STRING))) {
return $this->_error($msg->error());
}
# msgAuthenticationParameters::=OCTET STRING
my $auth_params;
if (!defined ($auth_params = $msg->process(OCTET_STRING))) {
return $this->_error($msg->error());
}
# We need to zero out the msgAuthenticationParameters in order
# to compute the HMAC properly.
if (my $len = length $auth_params) {
if ($len != 12) {
return $this->_error(
'The msgAuthenticationParameters length of %d is invalid', $len
);
}
substr ${$msg->reference}, ($msg->index() - 12), 12, pack 'x12';
}
# msgPrivacyParameters::=OCTET STRING
my $priv_params;
if (!defined ($priv_params = $msg->process(OCTET_STRING))) {
return $this->_error($msg->error());
}
# Validate the msgAuthoritativeEngineID and msgUserName
if ($this->{_discovered}) {
if ($msg_engine_id ne $this->_engine_id()) {
return $this->_error(
'The msgAuthoritativeEngineID "%s" was expected, but "%s" was ' .
'found', unpack('H*', $this->_engine_id()),
unpack 'H*', $msg_engine_id
);
}
if ($msg->security_name() ne $this->_user_name()) {
return $this->_error(
'The msgUserName "%s" was expected, but "%s" was found',
$this->_user_name(), $msg->security_name()
);
}
} else {
# Handle authoritativeEngineID discovery
if (!defined $this->_engine_id_discovery($msg_engine_id)) {
return $this->_error();
}
}
# Validate the incoming securityLevel
my $security_level = $msg->security_level();
if ($security_level > $this->{_security_level}) {
return $this->_error(
'The message securityLevel %d is greater than the configured ' .
'value %d', $security_level, $this->{_security_level}
);
}
if ($security_level > SECURITY_LEVEL_NOAUTHNOPRIV) {
# Authenticate the message
if (!defined $this->_authenticate_incoming_msg($msg, $auth_params)) {
return $this->_error();
}
# Synchronize the time
if (!$this->_synchronize($msg_engine_boots, $msg_engine_time)) {
return $this->_error();
}
# Check for timeliness
if (!defined $this->_timeliness($msg_engine_boots, $msg_engine_time)) {
return $this->_error();
}
if ($security_level > SECURITY_LEVEL_AUTHNOPRIV) {
# Validate the msgPrivacyParameters length.
if (length($priv_params) != 8) {
return $this->_error(
'The msgPrivacyParameters length of %d is invalid',
length $priv_params
);
}
# AES in the USM Section 3.1.2.1 - "The 128-bit IV is
# obtained as the concatenation of the... ...snmpEngineBoots,
# ...snmpEngineTime, and a local 64-bit integer. ...The
# 64-bit integer must be placed in the msgPrivacyParameters
# field..." We must prepend the snmpEngineBoots and
# snmpEngineTime as received in order to compute the IV.
if (($this->{_priv_protocol} eq PRIV_PROTOCOL_AESCFB128) ||
($this->{_priv_protocol} eq PRIV_PROTOCOL_DRAFT_AESCFB192) ||
($this->{_priv_protocol} eq PRIV_PROTOCOL_DRAFT_AESCFB256))
{
substr $priv_params, 0, 0, pack 'NN', $msg_engine_boots,
$msg_engine_time;
}
# encryptedPDU::=OCTET STRING
return $this->_decrypt_data($msg,
$priv_params,
$msg->process(OCTET_STRING));
}
}
return TRUE;
}
sub user_name
{
return $_[0]->{_user_name};
}
sub auth_protocol
{
my ($this) = @_;
if ($this->{_security_level} > SECURITY_LEVEL_NOAUTHNOPRIV) {
return $this->{_auth_protocol};
}
return AUTH_PROTOCOL_NONE;
}
sub auth_key
{
return $_[0]->{_auth_key};
}
sub priv_protocol
{
my ($this) = @_;
if ($this->{_security_level} > SECURITY_LEVEL_AUTHNOPRIV) {
return $this->{_priv_protocol};
}
return PRIV_PROTOCOL_NONE;
}
sub priv_key
{
return $_[0]->{_priv_key};
}
sub engine_id
{
return $_[0]->{_engine_id};
}
sub engine_boots
{
goto _engine_boots;
}
sub engine_time
{
goto &_engine_time;
}
sub security_level
{
return $_[0]->{_security_level};
}
sub security_model
{
# RFC 3411 - SnmpSecurityModel::=TEXTUAL-CONVENTION
return SECURITY_MODEL_USM;
}
sub security_name
{
goto &_user_name;
}
sub discovered
{
my ($this) = @_;
if ($this->{_security_level} > SECURITY_LEVEL_NOAUTHNOPRIV) {
return ($this->{_discovered} && $this->{_synchronized});
}
return $this->{_discovered};
}
# [private methods] ----------------------------------------------------------
sub _version
{
my ($this, $version) = @_;
if ($version != SNMP_VERSION_3) {
return $this->_error('The SNMP version %s is not supported', $version);
}
return $this->{_version} = $version;
}
sub _engine_id
{
my ($this, $engine_id) = @_;
if (@_ < 2) {
return $this->{_engine_id};
}
if ($engine_id =~ m/^(?:0x)?([A-F0-9]+)$/i) {
my $eid = pack 'H*', length($1) % 2 ? '0'.$1 : $1;
my $len = length $eid;
if ($len < 5 || $len > 32) {
return $this->_error(
'The authoritativeEngineID length of %d is out of range (5..32)',
$len
);
}
$this->{_engine_id} = $eid;
} else {
return $this->_error(
'The authoritativeEngineID "%s" is expected in hexadecimal format',
$engine_id
);
}
return $this->{_engine_id};
}
sub _user_name
{
my ($this, $user_name) = @_;
if (@_ == 2) {
if ($user_name eq q{}) {
return $this->_error('An empty userName was specified');
} elsif (length($user_name) > 32) {
return $this->_error(
'The userName length of %d is out of range (1..32)',
length $user_name
);
}
$this->{_user_name} = $user_name;
}
# RFC 3414 Section 4 - "Discovery... ...msgUserName of zero-length..."
return ($this->{_discovered}) ? $this->{_user_name} : q{};
}
sub _snmp_engine_init
{
my ($this) = @_;
if ($this->{_engine_id} eq q{}) {
# Initialize our snmpEngineID using the algorithm described
# in RFC 3411 - SnmpEngineID::=TEXTUAL-CONVENTION.
# The first bit is set to one to indicate that the RFC 3411
# algorithm is being used. The first fours bytes are to be
# the agent's SNMP management private enterprise number, but
# they are set to all zeros. The fifth byte is set to one to
# indicate that the final four bytes are an IPv4 address.
if (!defined $ENGINE_ID) {
$ENGINE_ID = eval {
require Sys::Hostname;
pack('H10', '8000000001') . gethostbyname Sys::Hostname::hostname();
};
# Fallback in case gethostbyname() or hostname() fail
if ($@) {
$ENGINE_ID = pack 'x11H2', '01';
}
}
$this->{_engine_id} = $ENGINE_ID;
}
$this->{_engine_boots} = 1;
$this->{_time_epoc} = $^T;
$this->{_synchronized} = TRUE;
$this->{_discovered} = TRUE;
return TRUE;
}
sub _auth_key
{
my ($this, $auth_key) = @_;
if (@_ == 2) {
if ($auth_key =~ m/^(?:0x)?([A-F0-9]+)$/i) {
$this->{_auth_key} = pack 'H*', length($1) % 2 ? '0'.$1 : $1;
if (!defined $this->_auth_key_validate()) {
return $this->_error();
}
} else {
return $this->_error(
'The authKey "%s" is expected in hexadecimal format', $auth_key
);
}
}
return $this->{_auth_key};
}
sub _auth_password
{
my ($this, $auth_password) = @_;
if (@_ == 2) {
if ($auth_password eq q{}) {
return $this->_error('An empty authentication password was specified');
}
$this->{_auth_password} = $auth_password;
}
return $this->{_auth_password};
}
{
my $protocols = {
'(?:hmac-)?md5(?:-96)?', AUTH_PROTOCOL_HMACMD5,
quotemeta AUTH_PROTOCOL_HMACMD5, AUTH_PROTOCOL_HMACMD5,
'(?:hmac-)?sha(?:-?1|-96)?', AUTH_PROTOCOL_HMACSHA,
quotemeta AUTH_PROTOCOL_HMACSHA, AUTH_PROTOCOL_HMACSHA,
};
sub _auth_protocol
{
my ($this, $proto) = @_;
if (@_ < 2) {
return $this->{_auth_protocol};
}
if ($proto eq q{}) {
return $this->_error('An empty authProtocol was specified');
}
for (keys %{$protocols}) {
if ($proto =~ /^$_$/i) {
return $this->{_auth_protocol} = $protocols->{$_};
}
}
return $this->_error('The authProtocol "%s" is unknown', $proto);
}
}
sub _priv_key
{
my ($this, $priv_key) = @_;
if (@_ == 2) {
if ($priv_key =~ m/^(?:0x)?([A-F0-9]+)$/i) {
$this->{_priv_key} = pack 'H*', length($1) % 2 ? '0'.$1 : $1;
if (!defined $this->_priv_key_validate()) {
return $this->_error();
}
} else {
return $this->_error(
'The privKey "%s" is expected in hexadecimal format', $priv_key
);
}
}
return $this->{_priv_key};
}
sub _priv_password
{
my ($this, $priv_password) = @_;
if (@_ == 2) {
if ($priv_password eq q{}) {
return $this->_error('An empty privacy password was specified');
}
$this->{_priv_password} = $priv_password;
}
return $this->{_priv_password};
}
{
my $protocols = {
'(?:cbc-)?des', PRIV_PROTOCOL_DES,
quotemeta PRIV_PROTOCOL_DES, PRIV_PROTOCOL_DES,
'(?:cbc-)?(?:3|triple-)des(?:-?ede)?', PRIV_PROTOCOL_DRAFT_3DESEDE,
quotemeta PRIV_PROTOCOL_DRAFT_3DESEDE, PRIV_PROTOCOL_DRAFT_3DESEDE,
'(?:(?:cfb)?128-?)?aes(?:-?128)?', PRIV_PROTOCOL_AESCFB128,
quotemeta PRIV_PROTOCOL_AESCFB128, PRIV_PROTOCOL_AESCFB128,
quotemeta PRIV_PROTOCOL_DRAFT_AESCFB128, PRIV_PROTOCOL_AESCFB128,
'(?:(?:cfb)?192-?)aes(?:-?128)?', PRIV_PROTOCOL_DRAFT_AESCFB192,
quotemeta PRIV_PROTOCOL_DRAFT_AESCFB192, PRIV_PROTOCOL_DRAFT_AESCFB192,
'(?:(?:cfb)?256-?)aes(?:-?128)?', PRIV_PROTOCOL_DRAFT_AESCFB256,
quotemeta PRIV_PROTOCOL_DRAFT_AESCFB256, PRIV_PROTOCOL_DRAFT_AESCFB256,
};
sub _priv_protocol
{
my ($this, $proto) = @_;
if (@_ < 2) {
return $this->{_priv_protocol};
}
if ($proto eq q{}) {
return $this->_error('An empty privProtocol was specified');
}
my $priv_proto;
for (keys %{$protocols}) {
if ($proto =~ /^$_$/i) {
$priv_proto = $protocols->{$_};
last;
}
}
if (!defined $priv_proto) {
return $this->_error('The privProtocol "%s" is unknown', $proto);
}
# Validate the support of the AES cipher algorithm. Attempt to
# load the Crypt::Rijndael module. If this module is not found,
# do not provide support for the AES Cipher Algorithm.
if (($priv_proto eq PRIV_PROTOCOL_AESCFB128) ||
($priv_proto eq PRIV_PROTOCOL_DRAFT_AESCFB192) ||
($priv_proto eq PRIV_PROTOCOL_DRAFT_AESCFB256))
{
if (defined (my $error = load_module('Crypt::Rijndael'))) {
return $this->_error(
'Support for privProtocol "%s" is unavailable %s', $proto, $error
);
}
}
return $this->{_priv_protocol} = $priv_proto;
}
}
sub _engine_boots
{
return ($_[0]->{_synchronized}) ? $_[0]->{_engine_boots} : 0;
}
sub _engine_time
{
my ($this) = @_;
return 0 if (!$this->{_synchronized});
$this->{_engine_time} = time() - $this->{_time_epoc};
if ($this->{_engine_time} > 2147483647) {
DEBUG_INFO('snmpEngineTime rollover');
if (++$this->{_engine_boots} == 2147483647) {
die 'FATAL: Unable to handle snmpEngineBoots value';
}
$this->{_engine_time} -= 2147483647;
$this->{_time_epoc} = time() - $this->{_engine_time};
if (!$this->{_authoritative}) {
$this->{_synchronized} = FALSE;
return $this->{_latest_engine_time} = 0;
}
}
if ($this->{_engine_time} < 0) {
die 'FATAL: Unable to handle negative snmpEngineTime value';
}
return $this->{_engine_time};
}
sub _security_params
{
my ($this) = @_;
# Clear any previous error messages
$this->_error_clear();
# We must have an usmUserName
if ($this->{_user_name} eq q{}) {
return $this->_error('The required userName was not specified');
}
# Define the authentication parameters
if ((defined $this->{_auth_password}) && ($this->{_discovered})) {
if (!defined $this->{_auth_key}) {
return $this->_error() if !defined $this->_auth_key_generate();
}
$this->{_auth_password} = undef;
}
if (defined $this->{_auth_key}) {
# Validate the key based on the protocol
if (!defined $this->_auth_key_validate()) {
return $this->_error('The authKey is invalid');
}
# Initialize the authentication data
if (!defined $this->_auth_data_init()) {
return $this->_error('Failed to initialize the authentication data');
}
if ($this->{_discovered}) {
$this->{_security_level} = SECURITY_LEVEL_AUTHNOPRIV;
}
}
# You must have authentication to have privacy
if (!defined ($this->{_auth_key}) && !defined $this->{_auth_password}) {
if (defined ($this->{_priv_key}) || defined $this->{_priv_password}) {
return $this->_error(
'The securityLevel is unsupported (privacy requires authentication)'
);
}
}
# Define the privacy parameters
if ((defined $this->{_priv_password}) && ($this->{_discovered})) {
if (!defined $this->{_priv_key}) {
return $this->_error() if !defined $this->_priv_key_generate();
}
$this->{_priv_password} = undef;
}
if (defined $this->{_priv_key}) {
# Validate the key based on the protocol
if (!defined $this->_priv_key_validate()) {
return $this->_error('The privKey is invalid');
}
# Initialize the privacy data
if (!defined $this->_priv_data_init()) {
return $this->_error('Failed to initialize the privacy data');
}
if ($this->{_discovered}) {
$this->{_security_level} = SECURITY_LEVEL_AUTHPRIV;
}
}
DEBUG_INFO('securityLevel = %d', $this->{_security_level});
return $this->{_security_level};
}
sub _engine_id_discovery
{
my ($this, $engine_id) = @_;
return TRUE if ($this->{_authoritative});
DEBUG_INFO('engineID = 0x%s', unpack 'H*', $engine_id || q{});
if (length($engine_id) < 5 || length($engine_id) > 32) {
return $this->_error(
'The msgAuthoritativeEngineID length of %d is out of range (5..32)',
length $engine_id
);
}
$this->{_engine_id} = $engine_id;
$this->{_discovered} = TRUE;
if (!defined $this->_security_params()) {
$this->{_discovered} = FALSE;
return $this->_error();
}
return TRUE;
}
sub _synchronize
{
my ($this, $msg_boots, $msg_time) = @_;
return TRUE if ($this->{_authoritative});
return TRUE if ($this->{_security_level} < SECURITY_LEVEL_AUTHNOPRIV);
if (($msg_boots > $this->_engine_boots()) ||
(($msg_boots == $this->_engine_boots()) &&
($msg_time > $this->{_latest_engine_time})))
{
DEBUG_INFO(
'update: engineBoots = %d, engineTime = %d', $msg_boots, $msg_time
);
$this->{_engine_boots} = $msg_boots;
$this->{_latest_engine_time} = $this->{_engine_time} = $msg_time;
$this->{_time_epoc} = time() - $this->{_engine_time};
if (!$this->{_synchronized}) {
$this->{_synchronized} = TRUE;
if (!defined $this->_security_params()) {
return ($this->{_synchronized} = FALSE);
}
}
return TRUE;
}
DEBUG_INFO(
'no update: engineBoots = %d, msgBoots = %d; ' .
'latestTime = %d, msgTime = %d',
$this->_engine_boots(), $msg_boots,
$this->{_latest_engine_time}, $msg_time
);
return TRUE;
}
sub _timeliness
{
my ($this, $msg_boots, $msg_time) = @_;
return TRUE if ($this->{_security_level} < SECURITY_LEVEL_AUTHNOPRIV);
# Retrieve a local copy of our snmpEngineBoots and snmpEngineTime
# to avoid the possibilty of using different values in each of
# the comparisons.
my $engine_time = $this->_engine_time();
my $engine_boots = $this->_engine_boots();
if ($engine_boots == 2147483647) {
$this->{_synchronized} = FALSE;
return $this->_error('The system is not in the time window');
}
if (!$this->{_authoritative}) {
if ($msg_boots < $engine_boots) {
return $this->_error('The message is not in the time window');
}
if (($msg_boots == $engine_boots) && ($msg_time < ($engine_time - 150))) {
return $this->_error('The message is not in the time window');
}
} else {
if ($msg_boots != $engine_boots) {
return $this->_error('The message is not in the time window');
}
if (($msg_time < ($engine_time - 150)) ||
($msg_time > ($engine_time + 150)))
{
return $this->_error('The message is not in the time window');
}
}
return TRUE;
}
sub _authenticate_outgoing_msg
{
my ($this, $msg, $auth_location) = @_;
if (!$auth_location) {
return $this->_error(
'Authentication failure (Unable to set msgAuthenticationParameters)'
);
}
# Set the msgAuthenticationParameters
substr ${$msg->reference}, -$auth_location, 12, $this->_auth_hmac($msg);
return TRUE;
}
sub _authenticate_incoming_msg
{
my ($this, $msg, $auth_params) = @_;
# Authenticate the message
if ($auth_params ne $this->_auth_hmac($msg)) {
return $this->_error('Authentication failure');
}
DEBUG_INFO('authentication passed');
return TRUE;
}
sub _auth_hmac
{
my ($this, $msg) = @_;
return q{} if (!defined($this->{_auth_data}) || !defined $msg);
return substr
$this->{_auth_data}->reset()->add(${$msg->reference()})->digest(), 0, 12;
}
sub _auth_data_init
{
my ($this) = @_;
if (!defined $this->{_auth_key}) {
return $this->_error('The required authKey is not defined');
}
return TRUE if defined $this->{_auth_data};
if ($this->{_auth_protocol} eq AUTH_PROTOCOL_HMACMD5) {
$this->{_auth_data} =
Digest::HMAC->new($this->{_auth_key}, 'Digest::MD5');
} elsif ($this->{_auth_protocol} eq AUTH_PROTOCOL_HMACSHA) {
$this->{_auth_data} =
Digest::HMAC->new($this->{_auth_key}, 'Digest::SHA1');
} else {
return $this->_error(
'The authProtocol "%s" is unknown', $this->{_auth_protocol}
);
}
return TRUE;
}
{
my $encrypt =
{
PRIV_PROTOCOL_DES, \&_priv_encrypt_des,
PRIV_PROTOCOL_DRAFT_3DESEDE, \&_priv_encrypt_3desede,
PRIV_PROTOCOL_AESCFB128, \&_priv_encrypt_aescfbxxx,
PRIV_PROTOCOL_DRAFT_AESCFB192, \&_priv_encrypt_aescfbxxx,
PRIV_PROTOCOL_DRAFT_AESCFB256, \&_priv_encrypt_aescfbxxx
};
sub _encrypt_data
{
# my ($this, $msg, $priv_params, $plain) = @_;
if (!exists $encrypt->{$_[0]->{_priv_protocol}}) {
return $_[0]->_error('Encryption error (Unknown protocol)');
}
if (!defined
$_[1]->prepare(
OCTET_STRING,
$_[0]->${\$encrypt->{$_[0]->{_priv_protocol}}}($_[2], $_[3])
)
)
{
return $_[0]->_error('Encryption error');
}
# Set the PDU buffer equal to the encryptedPDU
return $_[3] = $_[1]->clear();
}
}
{
my $decrypt =
{
PRIV_PROTOCOL_DES, \&_priv_decrypt_des,
PRIV_PROTOCOL_DRAFT_3DESEDE, \&_priv_decrypt_3desede,
PRIV_PROTOCOL_AESCFB128, \&_priv_decrypt_aescfbxxx,
PRIV_PROTOCOL_DRAFT_AESCFB192, \&_priv_decrypt_aescfbxxx,
PRIV_PROTOCOL_DRAFT_AESCFB256, \&_priv_decrypt_aescfbxxx
};
sub _decrypt_data
{
# my ($this, $msg, $priv_params, $cipher) = @_;
# Make sure there is data to decrypt.
if (!defined $_[3]) {
return $_[0]->_error($_[1]->error() || 'Decryption error (No data)');
}
if (!exists $decrypt->{$_[0]->{_priv_protocol}}) {
return $_[0]->_error('Decryption error (Unknown protocol)');
}
# Clear the Message buffer
$_[1]->clear();
# Put the decrypted data back into the Message buffer
if (!defined
$_[1]->prepend(
$_[0]->${\$decrypt->{$_[0]->{_priv_protocol}}}($_[2], $_[3])
)
)
{
return $_[0]->_error($_[1]->error());
}
return $_[0]->_error($_[1]->error()) if (!$_[1]->length());
# See if the decrypted data starts with a SEQUENCE
# and has a reasonable length.
my $msglen = $_[1]->process(SEQUENCE);
if ((!defined $msglen) || ($msglen > $_[1]->length())) {
return $_[0]->_error('Decryption error');
}
$_[1]->index(0); # Reset the index
DEBUG_INFO('privacy passed');
return TRUE;
}
}
sub _priv_data_init
{
my ($this) = @_;
if (!defined $this->{_priv_key}) {
return $this->_error('The required privKey is not defined');
}
return TRUE if defined $this->{_priv_data};
my $init =
{
PRIV_PROTOCOL_DES, \&_priv_data_init_des,
PRIV_PROTOCOL_DRAFT_3DESEDE, \&_priv_data_init_3desede,
PRIV_PROTOCOL_AESCFB128, \&_priv_data_init_aescfbxxx,
PRIV_PROTOCOL_DRAFT_AESCFB192, \&_priv_data_init_aescfbxxx,
PRIV_PROTOCOL_DRAFT_AESCFB256, \&_priv_data_init_aescfbxxx
};
if (!exists $init->{$this->{_priv_protocol}}) {
return $this->_error(
'The privProtocol "%s" is unknown', $this->{_priv_protocol}
);
}
return $this->${\$init->{$this->{_priv_protocol}}}();
}
sub _priv_data_init_des
{
my ($this) = @_;
if (!defined $this->{_priv_key}) {
return $this->_error('The required privKey is not defined');
}
# Create the DES object
$this->{_priv_data}->{des} =
Crypt::DES->new(substr $this->{_priv_key}, 0, 8);
# Extract the pre-IV
$this->{_priv_data}->{pre_iv} = substr $this->{_priv_key}, 8, 8;
# Initialize the salt
$this->{_priv_data}->{salt} = int rand ~0;
return TRUE;
}
sub _priv_encrypt_des
{
# my ($this, $priv_params, $plain) = @_;
if (!defined $_[0]->{_priv_data}) {
return $_[0]->_error('The required privacy data is not defined');
}
# Always pad the plain text data. "The actual pad value is
# irrelevant..." according RFC 3414 Section 8.1.1.2. However,
# there are some agents out there that expect "standard block
# padding" where each of the padding byte(s) are set to the size
# of the padding (even for data that is a multiple of block size).
my $pad = 8 - (length($_[2]) % 8);
$_[2] .= pack('C', $pad) x $pad;
# Create and set the salt
if ($_[0]->{_priv_data}->{salt}++ == ~0) {
$_[0]->{_priv_data}->{salt} = 0;
}
$_[1] = pack 'NN', $_[0]->{_engine_boots}, $_[0]->{_priv_data}->{salt};
# Create the initial vector (IV)
my $iv = $_[0]->{_priv_data}->{pre_iv} ^ $_[1];
my $cipher = q{};
# Perform Cipher Block Chaining (CBC)
while ($_[2] =~ /(.{8})/gs) {
$cipher .= $iv = $_[0]->{_priv_data}->{des}->encrypt($1 ^ $iv);
}
return $cipher;
}
sub _priv_decrypt_des
{
# my ($this, $priv_params, $cipher) = @_;
if (!defined $_[0]->{_priv_data}) {
return $_[0]->_error('The required privacy data is not defined');
}
if (length($_[1]) != 8) {
return $_[0]->_error(
'The msgPrivParameters length of %d is invalid', length $_[1]
);
}
if (length($_[2]) % 8) {
return $_[0]->_error(
'The DES cipher length is not a multiple of the block size'
);
}
# Create the initial vector (IV)
my $iv = $_[0]->{_priv_data}->{pre_iv} ^ $_[1];
my $plain = q{};
# Perform Cipher Block Chaining (CBC)
while ($_[2] =~ /(.{8})/gs) {
$plain .= $iv ^ $_[0]->{_priv_data}->{des}->decrypt($1);
$iv = $1;
}
return $plain;
}
sub _priv_data_init_3desede
{
my ($this) = @_;
if (!defined $this->{_priv_key}) {
return $this->_error('The required privKey is not defined');
}
# Create the 3 DES objects
$this->{_priv_data}->{des1} =
Crypt::DES->new(substr $this->{_priv_key}, 0, 8);
$this->{_priv_data}->{des2} =
Crypt::DES->new(substr $this->{_priv_key}, 8, 8);
$this->{_priv_data}->{des3} =
Crypt::DES->new(substr $this->{_priv_key}, 16, 8);
# Extract the pre-IV
$this->{_priv_data}->{pre_iv} = substr $this->{_priv_key}, 24, 8;
# Initialize the salt
$this->{_priv_data}->{salt} = int rand ~0;
# Assign a hash algorithm to "bit spread" the salt
if ($this->{_auth_protocol} eq AUTH_PROTOCOL_HMACMD5) {
$this->{_priv_data}->{hash} = Digest::MD5->new();
} elsif ($this->{_auth_protocol} eq AUTH_PROTOCOL_HMACSHA) {
$this->{_priv_data}->{hash} = Digest::SHA1->new();
}
return TRUE;
}
sub _priv_encrypt_3desede
{
# my ($this, $priv_params, $plain) = @_;
if (!defined $_[0]->{_priv_data}) {
return $_[0]->_error('The required privacy data is not defined');
}
# Pad the plain text data using "standard block padding".
my $pad = 8 - (length($_[2]) % 8);
$_[2] .= pack('C', $pad) x $pad;
# Create and set the salt
if ($_[0]->{_priv_data}->{salt}++ == ~0) {
$_[0]->{_priv_data}->{salt} = 0;
}
$_[1] = pack 'NN', $_[0]->{_engine_boots}, $_[0]->{_priv_data}->{salt};
# Draft 3DES-EDE for USM Section 5.1.1.1.2 - "To achieve effective
# bit spreading, the complete 8-octet 'salt' value SHOULD be
# hashed using the usmUserAuthProtocol."
if (exists $_[0]->{_priv_data}->{hash}) {
$_[1] = substr $_[0]->{_priv_data}->{hash}->add($_[1])->digest(), 0, 8;
}
# Create the initial vector (IV)
my $iv = $_[0]->{_priv_data}->{pre_iv} ^ $_[1];
my $cipher = q{};
# Perform Cipher Block Chaining (CBC)
while ($_[2] =~ /(.{8})/gs) {
$cipher .= $iv =
$_[0]->{_priv_data}->{des3}->encrypt(
$_[0]->{_priv_data}->{des2}->decrypt(
$_[0]->{_priv_data}->{des1}->encrypt($1 ^ $iv)
)
);
}
return $cipher;
}
sub _priv_decrypt_3desede
{
# my ($this, $priv_params, $cipher) = @_;
if (!defined $_[0]->{_priv_data}) {
return $_[0]->_error('The required privacy data is not defined');
}
if (length($_[1]) != 8) {
return $_[0]->_error(
'The msgPrivParameters length of %d is invalid', length $_[1]
);
}
if (length($_[2]) % 8) {
return $_[0]->_error(
'The CBC-3DES-EDE cipher length is not a multiple of the block size'
);
}
# Create the initial vector (IV)
my $iv = $_[0]->{_priv_data}->{pre_iv} ^ $_[1];
my $plain = q{};
# Perform Cipher Block Chaining (CBC)
while ($_[2] =~ /(.{8})/gs) {
$plain .=
$iv ^ $_[0]->{_priv_data}->{des1}->decrypt(
$_[0]->{_priv_data}->{des2}->encrypt(
$_[0]->{_priv_data}->{des3}->decrypt($1)
)
);
$iv = $1;
}
return $plain;
}
sub _priv_data_init_aescfbxxx
{
my ($this) = @_;
if (!defined $this->{_priv_key}) {
return $this->_error('The required privKey is not defined');
}
{
# Avoid a "strict subs" error if Crypt::Rijndael is not loaded.
no strict 'subs';
# Create the AES (Rijndael) object with a 128, 192, or 256 bit key.
$this->{_priv_data}->{aes} =
Crypt::Rijndael->new($this->{_priv_key}, Crypt::Rijndael::MODE_CFB());
}
# Initialize the salt
$this->{_priv_data}->{salt1} = int rand ~0;
$this->{_priv_data}->{salt2} = int rand ~0;
return TRUE;
}
sub _priv_encrypt_aescfbxxx
{
# my ($this, $priv_params, $plain) = @_;
if (!defined $_[0]->{_priv_data}) {
return $_[0]->_error('The required privacy data is not defined');
}
# Validate the plain text length
my $length = length $_[2];
if ($length <= 16) {
return $_[0]->_error(
'The AES plain text length is not greater than the block size'
);
}
# Create and set the salt
if ($_[0]->{_priv_data}->{salt1}++ == ~0) {
$_[0]->{_priv_data}->{salt1} = 0;
if ($_[0]->{_priv_data}->{salt2}++ == ~0) {
$_[0]->{_priv_data}->{salt2} = 0;
}
}
$_[1] = pack 'NN', $_[0]->{_priv_data}->{salt2},
$_[0]->{_priv_data}->{salt1};
# AES in the USM Section - Section 3.1.3 "The last ciphertext
# block is produced by exclusive-ORing the last plaintext segment
# of r bits (r is less or equal to 128) with the segment of the r
# most significant bits of the last output block."
# This operation is identical to those performed on the previous
# blocks except for the fact that the block can be less than the
# block size. We can just pad the last block and operate on it as
# usual and then ignore the padding after encrypting.
$_[2] .= "\000" x (16 - ($length % 16));
# Create the IV by concatenating "...the generating SNMP engine's
# 32-bit snmpEngineBoots, the SNMP engine's 32-bit snmpEngineTime,
# and a local 64-bit integer..."
$_[0]->{_priv_data}->{aes}->set_iv(
pack('NN', $_[0]->{_engine_boots}, $_[0]->{_engine_time}) . $_[1]
);
# Let the Crypt::Rijndael module perform 128 bit Cipher Feedback
# (CFB) and return the result minus the "internal" padding.
return substr $_[0]->{_priv_data}->{aes}->encrypt($_[2]), 0, $length;
}
sub _priv_decrypt_aescfbxxx
{
# my ($this, $priv_params, $cipher) = @_;
if (!defined $_[0]->{_priv_data}) {
return $_[0]->_error('The required privacy data is not defined');
}
# Validate the msgPrivParameters length. We assume that the
# msgAuthoritativeEngineBoots and msgAuthoritativeEngineTime
# have been prepended to the msgPrivParameters to create the
# required 128 bit IV.
if (length($_[1]) != 16) {
return $_[0]->_error(
'The AES IV length of %d is invalid', length $_[1]
);
}
# Validate the cipher length
my $length = length $_[2];
if ($length <= 16) {
return $_[0]->_error(
'The AES cipher length is not greater than the block size'
);
}
# AES in the USM Section - Section 3.1.4 "The last ciphertext
# block (whose size r is less or equal to 128) is less or equal
# to 128) is exclusive-ORed with the segment of the r most
# significant bits of the last output block to recover the last
# plaintext block of r bits."
# This operation is identical to those performed on the previous
# blocks except for the fact that the block can be less than the
# block size. We can just pad the last block and operate on it as
# usual and then ignore the padding after decrypting.
$_[2] .= "\000" x (16 - ($length % 16));
# Use the msgPrivParameters as the IV.
$_[0]->{_priv_data}->{aes}->set_iv($_[1]);
# Let the Crypt::Rijndael module perform 128 bit Cipher Feedback
# (CFB) and return the result minus the "internal" padding.
return substr $_[0]->{_priv_data}->{aes}->decrypt($_[2]), 0, $length;
}
sub _auth_key_generate
{
my ($this) = @_;
if (!defined($this->{_engine_id}) || !defined $this->{_auth_password}) {
return $this->_error('Unable to generate the authKey');
}
$this->{_auth_key} = $this->_password_localize($this->{_auth_password});
return $this->{_auth_key};
}
sub _auth_key_validate
{
my ($this) = @_;
my $key_len =
{
AUTH_PROTOCOL_HMACMD5, [ 16, 'HMAC-MD5' ],
AUTH_PROTOCOL_HMACSHA, [ 20, 'HMAC-SHA1' ],
};
if (!exists $key_len->{$this->{_auth_protocol}}) {
return $this->_error(
'The authProtocol "%s" is unknown', $this->{_auth_protocol}
);
}
if (length($this->{_auth_key}) != $key_len->{$this->{_auth_protocol}}->[0])
{
return $this->_error(
'The %s authKey length of %d is invalid, expected %d',
$key_len->{$this->{_auth_protocol}}->[1], length($this->{_auth_key}),
$key_len->{$this->{_auth_protocol}}->[0]
);
}
return TRUE;
}
sub _priv_key_generate
{
my ($this) = @_;
if (!defined($this->{_engine_id}) || !defined $this->{_priv_password}) {
return $this->_error('Unable to generate the privKey');
}
$this->{_priv_key} = $this->_password_localize($this->{_priv_password});
return $this->_error() if !defined $this->{_priv_key};
if ($this->{_priv_protocol} eq PRIV_PROTOCOL_DRAFT_3DESEDE) {
# Draft 3DES-EDE for USM Section 2.1 - "To acquire the necessary
# number of key bits, the password-to-key algorithm may be chained
# using its output as further input in order to generate an
# appropriate number of key bits."
$this->{_priv_key} .= $this->_password_localize($this->{_priv_key});
} elsif (($this->{_priv_protocol} eq PRIV_PROTOCOL_DRAFT_AESCFB192) ||
($this->{_priv_protocol} eq PRIV_PROTOCOL_DRAFT_AESCFB256))
{
# Draft AES in the USM Section 3.1.2.1 - "...if the size of the
# localized key is not large enough to generate an encryption
# key... ...set Kul = Kul || Hnnn(Kul) where Hnnn is the hash
# function for the authentication protocol..."
my $hnnn;
if ($this->{_auth_protocol} eq AUTH_PROTOCOL_HMACMD5) {
$hnnn = Digest::MD5->new();
} elsif ($this->{_auth_protocol} eq AUTH_PROTOCOL_HMACSHA) {
$hnnn = Digest::SHA1->new();
} else {
return $this->_error(
'The authProtocol "%s" is unknown', $this->{_auth_protocol}
);
}
$this->{_priv_key} .= $hnnn->add($this->{_priv_key})->digest();
}
# Truncate the privKey to the appropriate length.
my $key_len =
{
PRIV_PROTOCOL_DES, 16, # RFC 3414 Section 8.2.1
PRIV_PROTOCOL_DRAFT_3DESEDE, 32, # Draft 3DES for USM Section 5.2.1
PRIV_PROTOCOL_AESCFB128, 16, # AES in the USM Section 3.2.1
PRIV_PROTOCOL_DRAFT_AESCFB192, 24, # Draft AES in the USM Section 3.2.1
PRIV_PROTOCOL_DRAFT_AESCFB256, 32 # Draft AES in the USM Section 3.2.1
};
if (!exists $key_len->{$this->{_priv_protocol}}) {
return $this->_error(
'The privProtocol "%s" is unknown', $this->{_priv_protocol}
);
}
$this->{_priv_key} =
substr $this->{_priv_key}, 0, $key_len->{$this->{_priv_protocol}};
return $this->{_priv_key};
}
sub _priv_key_validate
{
my ($this) = @_;
my $key_len =
{
PRIV_PROTOCOL_DES, [ 16, 'CBC-DES' ],
PRIV_PROTOCOL_DRAFT_3DESEDE, [ 32, 'CBC-3DES-EDE' ],
PRIV_PROTOCOL_AESCFB128, [ 16, 'CFB128-AES-128' ],
PRIV_PROTOCOL_DRAFT_AESCFB192, [ 24, 'CFB128-AES-192' ],
PRIV_PROTOCOL_DRAFT_AESCFB256, [ 32, 'CFB128-AES-256' ]
};
if (!exists $key_len->{$this->{_priv_protocol}}) {
return $this->_error(
'The privProtocol "%s" is unknown', $this->{_priv_protocol}
);
}
if (length($this->{_priv_key}) != $key_len->{$this->{_priv_protocol}}->[0])
{
return $this->_error(
'The %s privKey length of %d is invalid, expected %d',
$key_len->{$this->{_priv_protocol}}->[1], length($this->{_priv_key}),
$key_len->{$this->{_priv_protocol}}->[0]
);
}
if ($this->{_priv_protocol} eq PRIV_PROTOCOL_DRAFT_3DESEDE) {
# Draft 3DES-EDE for USM Section 5.1.1.1.1 "The checks for difference
# and weakness... ...should be performed when the key is assigned.
# If any of the mandated tests fail, then the whole key MUST be
# discarded and an appropriate exception noted."
if (substr($this->{_priv_key}, 0, 8) eq substr $this->{_priv_key}, 8, 8)
{
return $this->_error(
'The CBC-3DES-EDE privKey is invalid (K1 equals K2)'
);
}
if (substr($this->{_priv_key}, 8, 8) eq substr $this->{_priv_key}, 16, 8)
{
return $this->_error(
'The CBC-3DES-EDE privKey is invalid (K2 equals K3)'
);
}
if (substr($this->{_priv_key}, 0, 8) eq substr $this->{_priv_key}, 16, 8)
{
return $this->_error(
'The CBC-3DES-EDE privKey is invalid (K1 equals K3)'
);
}
}
return TRUE;
}
sub _password_localize
{
my ($this, $password) = @_;
my $digests =
{
AUTH_PROTOCOL_HMACMD5, 'Digest::MD5',
AUTH_PROTOCOL_HMACSHA, 'Digest::SHA1',
};
if (!exists $digests->{$this->{_auth_protocol}}) {
return $this->_error(
'The authProtocol "%s" is unknown', $this->{_auth_protocol}
);
}
my $digest = $digests->{$this->{_auth_protocol}}->new;
# Create the initial digest using the password
my $d = my $pad = $password x ((2048 / length $password) + 1);
for (my $count = 0; $count < 2**20; $count += 2048) {
$digest->add(substr $d, 0, 2048, q{});
$d .= $pad;
}
$d = $digest->digest;
# Localize the key with the authoritativeEngineID
return $digest->add($d . $this->{_engine_id} . $d)->digest();
}
{
my %modules;
sub load_module
{
my ($module) = @_;
# We attempt to load the required module under the protection of an
# eval statement. If there is a failure, typically it is due to a
# missing module required by the requested module and we attempt to
# simplify the error message by just listing that module. We also
# need to track failures since require() only produces an error on
# the first attempt to load the module.
# NOTE: Contrary to our typical convention, a return value of "undef"
# actually means success and a defined value means error.
return $modules{$module} if exists $modules{$module};
if (!eval "require $module") {
if ($@ =~ /locate (\S+\.pm)/) {
$modules{$module} = sprintf '(Required module %s not found)', $1;
} else {
$modules{$module} = sprintf '(%s)', $@;
}
} else {
$modules{$module} = undef;
}
return $modules{$module};
}
}
# ============================================================================
1; # [end Net::SNMP::Security::USM]