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openssl: Only announce ECDH groups actually supported by OpenSSL

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Determined by whether the library provides curves for it or not.
For instance, in the OpenSSL 3 FIPS provider the Brainpool curves are
not included.  And in the Fedora package several weak curves are
explicitly patched out and the Brainpool curves are omitted even in
non-FIPS mode.
This commit is contained in:
Tobias Brunner 2021-11-16 14:34:03 +01:00
parent 03520a0d54
commit 46a6b06282
1 changed files with 76 additions and 16 deletions
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92
src/libstrongswan/plugins/openssl/openssl_plugin.c
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@ -28,6 +28,9 @@
#ifndef OPENSSL_NO_ENGINE
#include <openssl/engine.h>
#endif
#ifndef OPENSSL_NO_ECDH
#include <openssl/ec.h>
#endif
#include "openssl_plugin.h"
#include "openssl_util.h"
@ -486,10 +489,55 @@ METHOD(plugin_t, get_name, char*,
return "openssl";
}
#ifndef OPENSSL_NO_ECDH
/**
* Check if the given DH group is in the list of supported curves.
*/
static bool ecdh_group_supported(EC_builtin_curve *curves, size_t num_curves,
diffie_hellman_group_t group)
{
int j;
for (j = 0; j < num_curves; j++)
{
if (curves[j].nid == openssl_ecdh_group_to_nid(group))
{
return TRUE;
}
}
return FALSE;
}
/**
* Only add features for ECDH groups that are actually supported.
*/
static void add_ecdh_features(plugin_feature_t *features,
plugin_feature_t *to_add, int count, int *pos)
{
size_t num_curves;
int i;
num_curves = EC_get_builtin_curves(NULL, 0);
EC_builtin_curve curves[num_curves];
num_curves = EC_get_builtin_curves(curves, num_curves);
for (i = 0; i < count; i++)
{
if (to_add[i].kind != FEATURE_PROVIDE ||
ecdh_group_supported(curves, num_curves, to_add[i].arg.dh_group))
{
features[(*pos)++] = to_add[i];
}
}
}
#endif /* OPENSSL_NO_ECDH */
METHOD(plugin_t, get_features, int,
private_openssl_plugin_t *this, plugin_feature_t *features[])
{
static plugin_feature_t f[] = {
static plugin_feature_t f_base[] = {
/* we provide OpenSSL threading callbacks */
PLUGIN_PROVIDE(CUSTOM, "openssl-threading"),
/* crypters */
@ -635,21 +683,6 @@ METHOD(plugin_t, get_features, int,
PLUGIN_PROVIDE(AEAD, ENCR_CHACHA20_POLY1305, 32),
#endif /* OPENSSL_NO_CHACHA */
#endif /* OPENSSL_VERSION_NUMBER */
#ifndef OPENSSL_NO_ECDH
/* EC DH groups */
PLUGIN_REGISTER(DH, openssl_ec_diffie_hellman_create),
PLUGIN_PROVIDE(DH, ECP_256_BIT),
PLUGIN_PROVIDE(DH, ECP_384_BIT),
PLUGIN_PROVIDE(DH, ECP_521_BIT),
PLUGIN_PROVIDE(DH, ECP_224_BIT),
PLUGIN_PROVIDE(DH, ECP_192_BIT),
#if OPENSSL_VERSION_NUMBER >= 0x10002000L
PLUGIN_PROVIDE(DH, ECP_256_BP),
PLUGIN_PROVIDE(DH, ECP_384_BP),
PLUGIN_PROVIDE(DH, ECP_512_BP),
PLUGIN_PROVIDE(DH, ECP_224_BP),
#endif /* OPENSSL_VERSION_NUMBER */
#endif /* OPENSSL_NO_ECDH */
#ifndef OPENSSL_NO_DH
/* MODP DH groups */
PLUGIN_REGISTER(DH, openssl_diffie_hellman_create),
@ -809,6 +842,33 @@ METHOD(plugin_t, get_features, int,
PLUGIN_PROVIDE(RNG, RNG_STRONG),
PLUGIN_PROVIDE(RNG, RNG_WEAK),
};
static plugin_feature_t f_ecdh[] = {
#ifndef OPENSSL_NO_ECDH
/* EC DH groups */
PLUGIN_REGISTER(DH, openssl_ec_diffie_hellman_create),
PLUGIN_PROVIDE(DH, ECP_256_BIT),
PLUGIN_PROVIDE(DH, ECP_384_BIT),
PLUGIN_PROVIDE(DH, ECP_521_BIT),
PLUGIN_PROVIDE(DH, ECP_224_BIT),
PLUGIN_PROVIDE(DH, ECP_192_BIT),
#if OPENSSL_VERSION_NUMBER >= 0x10002000L
PLUGIN_PROVIDE(DH, ECP_256_BP),
PLUGIN_PROVIDE(DH, ECP_384_BP),
PLUGIN_PROVIDE(DH, ECP_512_BP),
PLUGIN_PROVIDE(DH, ECP_224_BP),
#endif /* OPENSSL_VERSION_NUMBER */
#endif /* OPENSSL_NO_ECDH */
};
static plugin_feature_t f[countof(f_base) + countof(f_ecdh)] = {};
static int count = 0;
if (!count)
{
plugin_features_add(f, f_base, countof(f_base), &count);
#ifndef OPENSSL_NO_ECDH
add_ecdh_features(f, f_ecdh, countof(f_ecdh), &count);
#endif
}
*features = f;
return countof(f);
}