ports/libssh
ports/libssh
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kex, pki, server, options: Filter algorithms in FIPS mode

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When in FIPS mode, filter the algorithms to enable only the allowed
ones.  If any algorithm is explicitly set through options or
configuration file, they are kept.

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Этот коммит содержится в:
Anderson Toshiyuki Sasaki 2019-05-22 18:33:14 +02:00 коммит произвёл Andreas Schneider
родитель 56041dc784
Коммит 54d76098ed
5 изменённых файлов: 137 добавлений и 14 удалений
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2
include/libssh/kex.h
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@ -39,11 +39,13 @@ int ssh_set_client_kex(ssh_session session);
int ssh_kex_select_methods(ssh_session session);
int ssh_verify_existing_algo(enum ssh_kex_types_e algo, const char *name);
char *ssh_keep_known_algos(enum ssh_kex_types_e algo, const char *list);
char *ssh_keep_fips_algos(enum ssh_kex_types_e algo, const char *list);
char **ssh_space_tokenize(const char *chain);
int ssh_get_kex1(ssh_session session);
char *ssh_find_matching(const char *in_d, const char *what_d);
const char *ssh_kex_get_supported_method(uint32_t algo);
const char *ssh_kex_get_default_methods(uint32_t algo);
const char *ssh_kex_get_fips_methods(uint32_t algo);
const char *ssh_kex_get_description(uint32_t algo);
char *ssh_client_select_hostkeys(ssh_session session);
int ssh_send_rekex(ssh_session session);

82
src/kex.c
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@ -136,11 +136,55 @@
#define KEY_EXCHANGE_SUPPORTED \
GEX_SHA1 \
KEY_EXCHANGE
#define KEX_METHODS_SIZE 10
/* RFC 8308 */
#define KEX_EXTENSION_CLIENT "ext-info-c"
/* Allowed algorithms in FIPS mode */
#define FIPS_ALLOWED_CIPHERS "aes256-gcm@openssh.com,"\
"aes256-ctr,"\
"aes256-cbc,"\
"aes128-gcm@openssh.com,"\
"aes128-ctr,"\
"aes128-cbc"
#define FIPS_ALLOWED_PUBLIC_KEY_ALGORITHMS "ecdsa-sha2-nistp521,"\
"ecdsa-sha2-nistp384,"\
"ecdsa-sha2-nistp256,"\
"rsa-sha2-512,"\
"rsa-sha2-256"
#define FIPS_ALLOWED_KEX "ecdh-sha2-nistp256,"\
"ecdh-sha2-nistp384,"\
"ecdh-sha2-nistp521,"\
"diffie-hellman-group-exchange-sha256,"\
"diffie-hellman-group16-sha512,"\
"diffie-hellman-group18-sha512"
#define FIPS_ALLOWED_MACS "hmac-sha2-256-etm@openssh.com,"\
"hmac-sha1-etm@openssh.com,"\
"hmac-sha2-512-etm@openssh.com,"\
"hmac-sha2-256,"\
"hmac-sha1,"\
"hmac-sha2-512"
/* NOTE: This is a fixed API and the index is defined by ssh_kex_types_e */
static const char *fips_methods[] = {
FIPS_ALLOWED_KEX,
FIPS_ALLOWED_PUBLIC_KEY_ALGORITHMS,
FIPS_ALLOWED_CIPHERS,
FIPS_ALLOWED_CIPHERS,
FIPS_ALLOWED_MACS,
FIPS_ALLOWED_MACS,
ZLIB,
ZLIB,
"",
"",
NULL
};
/* NOTE: This is a fixed API and the index is defined by ssh_kex_types_e */
static const char *default_methods[] = {
KEY_EXCHANGE,
@ -211,6 +255,14 @@ const char *ssh_kex_get_description(uint32_t algo) {
return ssh_kex_descriptions[algo];
}
const char *ssh_kex_get_fips_methods(uint32_t algo) {
if (algo >= KEX_METHODS_SIZE) {
return NULL;
}
return fips_methods[algo];
}
/**
* @internal
* @brief returns whether the first client key exchange algorithm or
@ -600,8 +652,13 @@ int ssh_set_client_kex(ssh_session session)
for (i = 0; i < KEX_METHODS_SIZE; i++) {
wanted = session->opts.wanted_methods[i];
if (wanted == NULL)
wanted = default_methods[i];
if (wanted == NULL) {
if (ssh_fips_mode()) {
wanted = fips_methods[i];
} else {
wanted = default_methods[i];
}
}
client->methods[i] = strdup(wanted);
if (client->methods[i] == NULL) {
ssh_set_error_oom(session);
@ -823,6 +880,27 @@ char *ssh_keep_known_algos(enum ssh_kex_types_e algo, const char *list)
return ssh_find_all_matching(supported_methods[algo], list);
}
/**
* @internal
*
* @brief Return a new allocated string containing only the FIPS allowed
* algorithms from the list.
*
* @param[in] algo The type of the methods to filter
* @param[in] list The list to be filtered
*
* @return A new allocated list containing only the FIPS allowed algorithms from
* the list; NULL in case of error.
*/
char *ssh_keep_fips_algos(enum ssh_kex_types_e algo, const char *list)
{
if (algo > SSH_LANG_S_C) {
return NULL;
}
return ssh_find_all_matching(fips_methods[algo], list);
}
int ssh_make_sessionid(ssh_session session)
{
ssh_string num = NULL;

27
src/options.c
Просмотреть файл

@ -223,10 +223,15 @@ int ssh_options_set_algo(ssh_session session,
{
char *p = NULL;
p = ssh_keep_known_algos(algo, list);
if (ssh_fips_mode()) {
p = ssh_keep_fips_algos(algo, list);
} else {
p = ssh_keep_known_algos(algo, list);
}
if (p == NULL) {
ssh_set_error(session, SSH_REQUEST_DENIED,
"Setting method: no algorithm for method \"%s\" (%s)",
"Setting method: no allowed algorithm for method \"%s\" (%s)",
ssh_kex_get_description(algo), list);
return -1;
}
@ -796,7 +801,11 @@ int ssh_options_set(ssh_session session, enum ssh_options_e type,
ssh_set_error_invalid(session);
return -1;
} else {
p = ssh_keep_known_algos(SSH_HOSTKEYS, v);
if (ssh_fips_mode()) {
p = ssh_keep_fips_algos(SSH_HOSTKEYS, v);
} else {
p = ssh_keep_known_algos(SSH_HOSTKEYS, v);
}
if (p == NULL) {
ssh_set_error(session, SSH_REQUEST_DENIED,
"Setting method: no known public key algorithm (%s)",
@ -1503,7 +1512,11 @@ static int ssh_bind_set_algo(ssh_bind sshbind,
{
char *p = NULL;
p = ssh_keep_known_algos(algo, list);
if (ssh_fips_mode()) {
p = ssh_keep_fips_algos(algo, list);
} else {
p = ssh_keep_known_algos(algo, list);
}
if (p == NULL) {
ssh_set_error(sshbind, SSH_REQUEST_DENIED,
"Setting method: no algorithm for method \"%s\" (%s)",
@ -1938,7 +1951,11 @@ int ssh_bind_options_set(ssh_bind sshbind, enum ssh_bind_options_e type,
ssh_set_error_invalid(sshbind);
return -1;
} else {
p = ssh_keep_known_algos(SSH_HOSTKEYS, v);
if (ssh_fips_mode()) {
p = ssh_keep_fips_algos(SSH_HOSTKEYS, v);
} else {
p = ssh_keep_known_algos(SSH_HOSTKEYS, v);
}
if (p == NULL) {
ssh_set_error(sshbind, SSH_REQUEST_DENIED,
"Setting method: no known public key algorithm (%s)",

25
src/pki.c
Просмотреть файл

@ -323,7 +323,11 @@ int ssh_key_algorithm_allowed(ssh_session session, const char *type)
if (session->client) {
allowed_list = session->opts.pubkey_accepted_types;
if (allowed_list == NULL) {
allowed_list = ssh_kex_get_default_methods(SSH_HOSTKEYS);
if (ssh_fips_mode()) {
allowed_list = ssh_kex_get_fips_methods(SSH_HOSTKEYS);
} else {
allowed_list = ssh_kex_get_default_methods(SSH_HOSTKEYS);
}
}
}
#ifdef WITH_SERVER
@ -2111,13 +2115,26 @@ int pki_key_check_hash_compatible(ssh_key key,
case SSH_KEYTYPE_DSS_CERT01:
case SSH_KEYTYPE_DSS:
if (hash_type == SSH_DIGEST_SHA1) {
return SSH_OK;
if (ssh_fips_mode()) {
SSH_LOG(SSH_LOG_WARN, "SHA1 is not allowed in FIPS mode");
return SSH_ERROR;
} else {
return SSH_OK;
}
}
break;
case SSH_KEYTYPE_RSA_CERT01:
case SSH_KEYTYPE_RSA:
if (hash_type == SSH_DIGEST_SHA1 ||
hash_type == SSH_DIGEST_SHA256 ||
if (hash_type == SSH_DIGEST_SHA1) {
if (ssh_fips_mode()) {
SSH_LOG(SSH_LOG_WARN, "SHA1 is not allowed in FIPS mode");
return SSH_ERROR;
} else {
return SSH_OK;
}
}
if (hash_type == SSH_DIGEST_SHA256 ||
hash_type == SSH_DIGEST_SHA512)
{
return SSH_OK;

15
src/server.c
Просмотреть файл

@ -142,7 +142,11 @@ int server_set_kex(ssh_session session)
if (session->opts.wanted_methods[SSH_HOSTKEYS]) {
allowed = session->opts.wanted_methods[SSH_HOSTKEYS];
} else {
allowed = ssh_kex_get_default_methods(SSH_HOSTKEYS);
if (ssh_fips_mode()) {
allowed = ssh_kex_get_fips_methods(SSH_HOSTKEYS);
} else {
allowed = ssh_kex_get_default_methods(SSH_HOSTKEYS);
}
}
/* It is expected for the list of allowed hostkeys to be ordered by
@ -163,8 +167,13 @@ int server_set_kex(ssh_session session)
}
for (i = 0; i < 10; i++) {
if ((wanted = session->opts.wanted_methods[i]) == NULL) {
wanted = ssh_kex_get_default_methods(i);
wanted = session->opts.wanted_methods[i];
if (wanted == NULL) {
if (ssh_fips_mode()) {
wanted = ssh_kex_get_fips_methods(i);
} else {
wanted = ssh_kex_get_default_methods(i);
}
}
server->methods[i] = strdup(wanted);
if (server->methods[i] == NULL) {