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Added HMAC support to GPG encryption modes, closes #58

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This commit is contained in:
Michael Rash 2013-04-22 20:45:59 -04:00
parent 2f72960e0f
commit f02cc0ddd2
12 changed files with 219 additions and 39 deletions
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5
ChangeLog
View File

@ -2,7 +2,10 @@ fwknop-2.5 (//2013):
- Major release of new functionality - HMAC authenticated encryption
support in the encrypt-then-authenticate model for SPA communications.
Supported HMAC digests include MD5, SHA1, SHA256, SHA384, and SHA512.
The default is HMAC-SHA256 when HMAC is used.
The default is HMAC-SHA256 when HMAC is used. HMAC is supported for both
Rijndael and GPG encrypted SPA packet data, and provides a significant
security benefit since the HMAC verification is more simplisitic than
decryption operations (particularly for GPG).
- [libfko] Significant bug fix to honor the full encryption key length for
user-supplied Rijndael keys > 16 bytes long. Previous to this fix,
only the first 16 bytes of a key were actually used in the encryption/

1
Makefile.am
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@ -248,6 +248,7 @@ EXTRA_DIST = \
test/tests/rijndael_hmac.pl \
test/tests/rijndael_backwards_compatibility.pl \
test/tests/gpg_no_pw.pl \
test/tests/gpg_no_pw_hmac.pl \
test/tests/gpg.pl \
test/tests/rijndael_fuzzing.pl \
test/tests/perl_FKO_module.pl \

35
lib/cipher_funcs.c
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@ -355,5 +355,40 @@ add_salted_str(fko_ctx_t ctx)
return(FKO_SUCCESS);
}
/* See if we need to add the "hQ" string to the front of the
* encrypted data.
*/
int
add_gpg_prefix(fko_ctx_t ctx)
{
char *tbuf;
if(strncmp(ctx->encrypted_msg,
B64_GPG_PREFIX, B64_GPG_PREFIX_STR_LEN))
{
/* We need to realloc space for the prefix.
*/
tbuf = realloc(ctx->encrypted_msg, ctx->encrypted_msg_len
+ B64_GPG_PREFIX_STR_LEN+1);
if(tbuf == NULL)
return(FKO_ERROR_MEMORY_ALLOCATION);
memmove(tbuf+B64_GPG_PREFIX_STR_LEN, tbuf, ctx->encrypted_msg_len);
ctx->encrypted_msg = memcpy(tbuf,
B64_GPG_PREFIX, B64_GPG_PREFIX_STR_LEN);
/* Adjust the encoded msg len for added SALT value and Make sure we
* are still a properly NULL-terminated string (Ubuntu was one system
* for which this was an issue).
*/
ctx->encrypted_msg_len += B64_GPG_PREFIX_STR_LEN;
tbuf[ctx->encrypted_msg_len] = '\0';
ctx->added_gpg_prefix = 1;
}
return(FKO_SUCCESS);
}
/***EOF***/

1
lib/cipher_funcs.h
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@ -48,6 +48,7 @@ size_t rij_decrypt(unsigned char *in, size_t len,
const char *key, const int key_len,
unsigned char *out, int encryption_mode);
int add_salted_str(fko_ctx_t ctx);
int add_gpg_prefix(fko_ctx_t ctx);
#endif /* CIPHER_FUNCS_H */

1
lib/fko_context.h
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@ -91,6 +91,7 @@ struct fko_context {
char *msg_hmac;
int msg_hmac_len;
int added_salted_str;
int added_gpg_prefix;
/* State info */
unsigned short state;

22
lib/fko_encryption.c
View File

@ -332,7 +332,6 @@ gpg_encrypt(fko_ctx_t ctx, const char *enc_key)
static int
gpg_decrypt(fko_ctx_t ctx, const char *dec_key)
{
char *tbuf;
unsigned char *cipher;
size_t cipher_len;
int res, pt_len;
@ -340,25 +339,8 @@ gpg_decrypt(fko_ctx_t ctx, const char *dec_key)
/* Now see if we need to add the "hQ" string to the front of the
* base64-encoded-GPG-encrypted data.
*/
if(strncmp(ctx->encrypted_msg, B64_GPG_PREFIX, B64_GPG_PREFIX_STR_LEN))
{
/* We need to realloc space for the GPG prefix of hQ.
*/
tbuf = realloc(ctx->encrypted_msg, ctx->encrypted_msg_len + 12);
if(tbuf == NULL)
return(FKO_ERROR_MEMORY_ALLOCATION);
memmove(tbuf+B64_GPG_PREFIX_STR_LEN, tbuf, ctx->encrypted_msg_len);
ctx->encrypted_msg = memcpy(tbuf, B64_GPG_PREFIX, B64_GPG_PREFIX_STR_LEN);
/* Adjust encrypted msg length for GnuPG prefix and make sure we are still
* a properly NULL-terminated string (Ubuntu was one system for
* which this was an issue).
*/
ctx->encrypted_msg_len += B64_GPG_PREFIX_STR_LEN;
tbuf[ctx->encrypted_msg_len] = '\0';
}
if(! ctx->added_gpg_prefix)
add_gpg_prefix(ctx);
/* Create a bucket for the (base64) decoded encrypted data and get the
* raw cipher data.

25
lib/fko_hmac.c
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@ -94,11 +94,26 @@ int fko_verify_hmac(fko_ctx_t ctx,
ctx->encrypted_msg = tbuf;
ctx->encrypted_msg_len -= hmac_b64_digest_len;
/* See if we need to add the "Salted__" string to the front of the
* encrypted data.
*/
if(! ctx->added_salted_str)
res = add_salted_str(ctx);
if(ctx->encryption_mode == FKO_ENC_MODE_ASYMMETRIC)
{
/* See if we need to add the "hQ" string to the front of the
* encrypted data.
*/
if(! ctx->added_gpg_prefix)
{
res = add_gpg_prefix(ctx);
}
}
else
{
/* See if we need to add the "Salted__" string to the front of the
* encrypted data.
*/
if(! ctx->added_salted_str)
{
res = add_salted_str(ctx);
}
}
if (res != FKO_SUCCESS)
{

20
server/access.c
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@ -1076,7 +1076,7 @@ parse_access_file(fko_srv_options_t *opts)
}
add_acc_string(&(curr_acc->hmac_key_base64), val);
add_acc_b64_string(&(curr_acc->hmac_key),
&curr_acc->hmac_key_len, curr_acc->hmac_key_base64);
&(curr_acc->hmac_key_len), curr_acc->hmac_key_base64);
}
else if(CONF_VAR_IS(var, "HMAC_KEY"))
{
@ -1457,7 +1457,12 @@ dump_access_list(const fko_srv_options_t *opts)
"==============================================================\n"
" OPEN_PORTS: %s\n"
" RESTRICT_PORTS: %s\n"
" KEY: <see the access.conf file>\n"
" KEY: %s\n"
" KEY_BASE64: %s\n"
" KEY_LEN: %d\n"
" HMAC_KEY: %s\n"
" HMAC_KEY_BASE64: %s\n"
" HMAC_KEY_LEN: %d\n"
" FW_ACCESS_TIMEOUT: %i\n"
" ENABLE_CMD_EXEC: %s\n"
" CMD_EXEC_USER: %s\n"
@ -1469,7 +1474,7 @@ dump_access_list(const fko_srv_options_t *opts)
" ACCESS_EXPIRE: %s" /* asctime() adds a newline */
" GPG_HOME_DIR: %s\n"
" GPG_DECRYPT_ID: %s\n"
" GPG_DECRYPT_PW: <see the access.conf file>\n"
" GPG_DECRYPT_PW: %s\n"
" GPG_REQUIRE_SIG: %s\n"
"GPG_IGNORE_SIG_VERIFY_ERROR: %s\n"
" GPG_REMOTE_ID: %s\n",
@ -1477,7 +1482,12 @@ dump_access_list(const fko_srv_options_t *opts)
acc->source,
(acc->open_ports == NULL) ? "<not set>" : acc->open_ports,
(acc->restrict_ports == NULL) ? "<not set>" : acc->restrict_ports,
//(acc->key == NULL) ? "<not set>" : acc->key,
(acc->key == NULL) ? "<not set>" : "<see the access.conf file>",
(acc->key_base64 == NULL) ? "<not set>" : "<see the access.conf file>",
acc->key_len ? acc->key_len : 0,
(acc->hmac_key == NULL) ? "<not set>" : "<see the access.conf file>",
(acc->hmac_key_base64 == NULL) ? "<not set>" : "<see the access.conf file>",
acc->hmac_key_len ? acc->hmac_key_len : 0,
acc->fw_access_timeout,
acc->enable_cmd_exec ? "Yes" : "No",
(acc->cmd_exec_user == NULL) ? "<not set>" : acc->cmd_exec_user,
@ -1489,7 +1499,7 @@ dump_access_list(const fko_srv_options_t *opts)
(acc->access_expire_time > 0) ? asctime(localtime(&acc->access_expire_time)) : "<not set>\n",
(acc->gpg_home_dir == NULL) ? "<not set>" : acc->gpg_home_dir,
(acc->gpg_decrypt_id == NULL) ? "<not set>" : acc->gpg_decrypt_id,
//(acc->gpg_decrypt_pw == NULL) ? "<not set>" : acc->gpg_decrypt_pw,
(acc->gpg_decrypt_pw == NULL) ? "<not set>" : "<see the access.conf file>",
acc->gpg_require_sig ? "Yes" : "No",
acc->gpg_ignore_sig_error ? "Yes" : "No",
(acc->gpg_remote_id == NULL) ? "<not set>" : acc->gpg_remote_id

3
server/incoming_spa.c
View File

@ -428,7 +428,8 @@ incoming_spa(fko_srv_options_t *opts)
if(acc->gpg_decrypt_pw != NULL || acc->gpg_allow_no_pw)
{
res = fko_new_with_data(&ctx, (char *)spa_pkt->packet_data, NULL,
0, acc->encryption_mode, NULL, 0, 0);
0, FKO_ENC_MODE_ASYMMETRIC, acc->hmac_key,
acc->hmac_key_len, acc->hmac_type);
attempted_decrypt = 1;
if(res != FKO_SUCCESS)
{

28
test/test-fwknop.pl
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@ -72,6 +72,7 @@ our %cf = (
'gpg_access' => "$conf_dir/gpg_access.conf",
'legacy_iv_access' => "$conf_dir/legacy_iv_access.conf",
'gpg_no_pw_access' => "$conf_dir/gpg_no_pw_access.conf",
'gpg_no_pw_hmac_access' => "$conf_dir/gpg_no_pw_hmac_access.conf",
'tcp_server' => "$conf_dir/tcp_server_fwknopd.conf",
'tcp_pcap_filter' => "$conf_dir/tcp_pcap_filter_fwknopd.conf",
'icmp_pcap_filter' => "$conf_dir/icmp_pcap_filter_fwknopd.conf",
@ -175,6 +176,7 @@ my @test_files = (
"$tests_dir/perl_FKO_module.pl",
"$tests_dir/python_fko.pl",
"$tests_dir/gpg_no_pw.pl",
"$tests_dir/gpg_no_pw_hmac.pl",
"$tests_dir/gpg.pl",
);
#================== end config ===================
@ -190,6 +192,7 @@ our @rijndael_replay_attacks = (); ### from tests/rijndael_replay_attacks.pl
our @rijndael_hmac = (); ### from tests/rijndael_hmac.pl
our @rijndael_fuzzing = (); ### from tests/rijndael_fuzzing.pl
our @gpg_no_pw = (); ### from tests/gpg_now_pw.pl
our @gpg_no_pw_hmac = (); ### from tests/gpg_now_pw_hmac.pl
our @gpg = (); ### from tests/gpg.pl
our @perl_FKO_module = (); ### from tests/perl_FKO_module.pl
our @python_fko = (); ### from tests/python_fko.pl
@ -281,6 +284,8 @@ our $MATCH_ANY = 1;
our $MATCH_ALL = 2;
our $REQUIRE_SUCCESS = 0;
our $REQUIRE_FAILURE = 1;
my $ENC_RIJNDAEL = 1;
my $ENC_GPG = 2;
our $LINUX = 1;
our $FREEBSD = 2;
our $MACOSX = 3;
@ -410,6 +415,11 @@ our $default_server_gpg_args_no_pw = "LD_LIBRARY_PATH=$lib_dir " .
"-a $cf{'gpg_no_pw_access'} $intf_str " .
"-d $default_digest_file -p $default_pid_file";
our $default_server_gpg_args_no_pw_hmac = "LD_LIBRARY_PATH=$lib_dir " .
"$valgrind_str $fwknopdCmd -c $cf{'def'} " .
"-a $cf{'gpg_no_pw_hmac_access'} $intf_str " .
"-d $default_digest_file -p $default_pid_file";
### point the compiled binaries at the local libary path
### instead of any installed libfko instance
$ENV{'LD_LIBRARY_PATH'} = $lib_dir;
@ -454,6 +464,7 @@ my @tests = (
@perl_FKO_module,
@python_fko,
@gpg_no_pw,
@gpg_no_pw_hmac,
@gpg,
);
@ -1101,6 +1112,8 @@ sub client_send_spa_packet() {
}
if ($is_hmac_type and $hmac_key) {
my $enc_mode = $ENC_RIJNDAEL;
$enc_mode = $ENC_GPG if $test_hr->{'msg'} =~ /GPG\s/;
unless (&openssl_hmac_verification($encrypted_msg,
$encoded_msg, '', $hmac_key, $b64_decode_key,
$hmac_digest, $hmac_mode)) {
@ -2473,7 +2486,7 @@ sub perl_fko_module_complete_cycle_hmac() {
if ($enable_openssl_compatibility_tests) {
unless (&openssl_hmac_verification($encrypted_msg,
'', $msg, $hmac_key, 0, $hmac_digest,
&hmac_type_to_str($hmac_type))) {
&hmac_type_to_str($hmac_type), $ENC_RIJNDAEL)) {
$rv = 0;
}
@ -4170,7 +4183,7 @@ sub immediate_binding() {
sub openssl_hmac_verification() {
my ($encrypted_msg, $encoded_msg, $access_msg, $tmp_key,
$b64_decode_key, $hmac_digest, $hmac_mode) = @_;
$b64_decode_key, $hmac_digest, $hmac_mode, $enc_mode) = @_;
$openssl_hmac_ctr++;
@ -4214,8 +4227,13 @@ sub openssl_hmac_verification() {
}
### transform encrypted message into the format that openssl expects
$enc_msg_without_hmac = 'U2FsdGVkX1' . $enc_msg_without_hmac
unless $enc_msg_without_hmac =~ /^U2FsdGVkX1/;
if ($enc_mode) {
$enc_msg_without_hmac = 'U2FsdGVkX1' . $enc_msg_without_hmac
unless $enc_msg_without_hmac =~ /^U2FsdGVkX1/;
} else {
$enc_msg_without_hmac = 'hQ' . $enc_msg_without_hmac
unless $enc_msg_without_hmac =~ /^hQ/;
}
&write_test_file(" Calculating HMAC over: '$enc_msg_without_hmac'\n",
$curr_test_file);
@ -5449,7 +5467,7 @@ sub file_find_regex() {
}
sub remove_permissions_warnings() {
system qq|perl -p -i -e 's/.*not owned by current effective.*\n//' $output_dir/*|;
system qq|perl -p -i -e 's/.*not owned by current effective.*\n//' $output_dir/*.test|;
return;
}

115
test/tests/gpg_no_pw_hmac.pl Normal file
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@ -0,0 +1,115 @@
@gpg_no_pw_hmac = (
### no password GPG testing
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'complete cycle (tcp/22 ssh)',
'function' => \&spa_cycle,
'cmdline' => "$default_client_gpg_args_no_homedir "
. "--gpg-home-dir $gpg_client_home_dir_no_pw "
. "--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'fw_rule_created' => $NEW_RULE_REQUIRED,
'fw_rule_removed' => $NEW_RULE_REMOVED,
'key_file' => $cf{'rc_hmac_b64_key'},
'fatal' => $NO
},
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'complete cycle (tcp/23 telnet)',
'function' => \&spa_cycle,
'cmdline' => "LD_LIBRARY_PATH=$lib_dir $valgrind_str " .
"$fwknopCmd -A tcp/23 -a $fake_ip -D $loopback_ip --get-key " .
"$local_key_file --verbose --verbose " .
"--gpg-recipient-key $gpg_server_key " .
"--gpg-signer-key $gpg_client_key " .
"--gpg-home-dir $gpg_client_home_dir_no_pw " .
"--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'fw_rule_created' => $NEW_RULE_REQUIRED,
'fw_rule_removed' => $NEW_RULE_REMOVED,
'key_file' => $cf{'rc_hmac_b64_key'},
'fatal' => $NO
},
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'complete cycle (tcp/9418 git)',
'function' => \&spa_cycle,
'cmdline' => "LD_LIBRARY_PATH=$lib_dir $valgrind_str " .
"$fwknopCmd -A tcp/9418 -a $fake_ip -D $loopback_ip --get-key " .
"$local_key_file --verbose --verbose " .
"--gpg-recipient-key $gpg_server_key " .
"--gpg-signer-key $gpg_client_key " .
"--gpg-home-dir $gpg_client_home_dir_no_pw " .
"--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'fw_rule_created' => $NEW_RULE_REQUIRED,
'fw_rule_removed' => $NEW_RULE_REMOVED,
'key_file' => $cf{'rc_hmac_b64_key'},
'fatal' => $NO
},
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'complete cycle (tcp/60001 git)',
'function' => \&spa_cycle,
'cmdline' => "LD_LIBRARY_PATH=$lib_dir $valgrind_str " .
"$fwknopCmd -A tcp/60001 -a $fake_ip -D $loopback_ip --get-key " .
"$local_key_file --verbose --verbose " .
"--gpg-recipient-key $gpg_server_key " .
"--gpg-signer-key $gpg_client_key " .
"--gpg-home-dir $gpg_client_home_dir_no_pw " .
"--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'fw_rule_created' => $NEW_RULE_REQUIRED,
'fw_rule_removed' => $NEW_RULE_REMOVED,
'key_file' => $cf{'rc_hmac_b64_key'},
'fatal' => $NO
},
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'complete cycle (udp/53 dns)',
'function' => \&spa_cycle,
'cmdline' => "LD_LIBRARY_PATH=$lib_dir $valgrind_str " .
"$fwknopCmd -A udp/53 -a $fake_ip -D $loopback_ip --get-key " .
"$local_key_file --verbose --verbose " .
"--gpg-recipient-key $gpg_server_key " .
"--gpg-signer-key $gpg_client_key " .
"--gpg-home-dir $gpg_client_home_dir_no_pw " .
"--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'fw_rule_created' => $NEW_RULE_REQUIRED,
'fw_rule_removed' => $NEW_RULE_REMOVED,
'key_file' => $cf{'rc_hmac_b64_key'},
'fatal' => $NO
},
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'replay attack detection',
'function' => \&replay_detection,
'cmdline' => "$default_client_gpg_args_no_homedir "
. "--gpg-home-dir $gpg_client_home_dir_no_pw "
. "--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'key_file' => $cf{'rc_hmac_b64_key'},
'fatal' => $NO
},
{
'category' => 'GPG (no pw) HMAC',
'subcategory' => 'client+server',
'detail' => 'detect replay #1 (GnuPG prefix)',
'function' => \&replay_detection,
'pkt_prefix' => 'hQ',
'cmdline' => "$default_client_gpg_args_no_homedir "
. "--gpg-home-dir $gpg_client_home_dir_no_pw "
. "--rc-file $cf{'rc_hmac_b64_key'}",
'fwknopd_cmdline' => $default_server_gpg_args_no_pw_hmac,
'replay_positive_output_matches' => [qr/Data\sis\snot\sa\svalid\sSPA\smessage\sformat/],
'fatal' => $NO
},
);

2
test/tests/rijndael_replay_attacks.pl
View File

@ -34,6 +34,4 @@
"$fwknopdCmd $default_server_conf_args $intf_str",
'fatal' => $NO
},
);