From d2b061bea524012edde2915aa95fc4cb6a6f3ae9 Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Tue, 30 May 2023 01:21:48 -0400
Subject: [PATCH] Enable PKINIT if at least one group is available
OpenSSL may no longer allow decoding of non-well-known Diffie-Hellman
group parameters as EVP_PKEY objects in FIPS mode. However, OpenSSL
does not know about MODP group 2 (1024-bit), which is considered as a
custom group. As a consequence, the PKINIT kdcpreauth module fails to
load in FIPS mode.
Allow initialization of PKINIT plugin if at least one of the MODP
well-known group parameters successfully decodes.
[ghudson@mit.edu: minor commit message and code edits]
ticket: 9096 (new)
(cherry picked from commit 509d8db922e9ad6f108883838473b6178f89874a)
---
src/plugins/preauth/pkinit/pkinit_clnt.c | 2 +-
src/plugins/preauth/pkinit/pkinit_crypto.h | 3 +-
.../preauth/pkinit/pkinit_crypto_openssl.c | 76 +++++++++++--------
src/plugins/preauth/pkinit/pkinit_srv.c | 2 +-
src/plugins/preauth/pkinit/pkinit_trace.h | 3 +
5 files changed, 51 insertions(+), 35 deletions(-)
diff --git a/src/plugins/preauth/pkinit/pkinit_clnt.c b/src/plugins/preauth/pkinit/pkinit_clnt.c
index 725d5bc438..ea9ba454df 100644
--- a/src/plugins/preauth/pkinit/pkinit_clnt.c
+++ b/src/plugins/preauth/pkinit/pkinit_clnt.c
@@ -1378,7 +1378,7 @@ pkinit_client_plugin_init(krb5_context context,
if (retval)
goto errout;
- retval = pkinit_init_plg_crypto(&ctx->cryptoctx);
+ retval = pkinit_init_plg_crypto(context, &ctx->cryptoctx);
if (retval)
goto errout;
diff --git a/src/plugins/preauth/pkinit/pkinit_crypto.h b/src/plugins/preauth/pkinit/pkinit_crypto.h
index 9fa315d7a0..8bdbea8e95 100644
--- a/src/plugins/preauth/pkinit/pkinit_crypto.h
+++ b/src/plugins/preauth/pkinit/pkinit_crypto.h
@@ -103,7 +103,8 @@ typedef struct _pkinit_cert_matching_data {
/*
* Functions to initialize and cleanup crypto contexts
*/
-krb5_error_code pkinit_init_plg_crypto(pkinit_plg_crypto_context *);
+krb5_error_code pkinit_init_plg_crypto(krb5_context,
+ pkinit_plg_crypto_context *);
void pkinit_fini_plg_crypto(pkinit_plg_crypto_context);
krb5_error_code pkinit_init_req_crypto(pkinit_req_crypto_context *);
diff --git a/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c b/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
index 263ef7845e..d646073d55 100644
--- a/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
+++ b/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
@@ -47,7 +47,8 @@
static krb5_error_code pkinit_init_pkinit_oids(pkinit_plg_crypto_context );
static void pkinit_fini_pkinit_oids(pkinit_plg_crypto_context );
-static krb5_error_code pkinit_init_dh_params(pkinit_plg_crypto_context );
+static krb5_error_code pkinit_init_dh_params(krb5_context,
+ pkinit_plg_crypto_context);
static void pkinit_fini_dh_params(pkinit_plg_crypto_context );
static krb5_error_code pkinit_init_certs(pkinit_identity_crypto_context ctx);
@@ -951,7 +952,8 @@ oerr_cert(krb5_context context, krb5_error_code code, X509_STORE_CTX *certctx,
}
krb5_error_code
-pkinit_init_plg_crypto(pkinit_plg_crypto_context *cryptoctx)
+pkinit_init_plg_crypto(krb5_context context,
+ pkinit_plg_crypto_context *cryptoctx)
{
krb5_error_code retval = ENOMEM;
pkinit_plg_crypto_context ctx = NULL;
@@ -969,7 +971,7 @@ pkinit_init_plg_crypto(pkinit_plg_crypto_context *cryptoctx)
if (retval)
goto out;
- retval = pkinit_init_dh_params(ctx);
+ retval = pkinit_init_dh_params(context, ctx);
if (retval)
goto out;
@@ -1278,30 +1280,36 @@ pkinit_fini_pkinit_oids(pkinit_plg_crypto_context ctx)
ASN1_OBJECT_free(ctx->id_kp_serverAuth);
}
-static krb5_error_code
-pkinit_init_dh_params(pkinit_plg_crypto_context plgctx)
+static int
+try_import_group(krb5_context context, const krb5_data *params,
+ const char *name, EVP_PKEY **pkey_out)
{
- krb5_error_code retval = ENOMEM;
-
- plgctx->dh_1024 = decode_dh_params(&oakley_1024);
- if (plgctx->dh_1024 == NULL)
- goto cleanup;
-
- plgctx->dh_2048 = decode_dh_params(&oakley_2048);
- if (plgctx->dh_2048 == NULL)
- goto cleanup;
+ *pkey_out = decode_dh_params(params);
+ if (*pkey_out == NULL)
+ TRACE_PKINIT_DH_GROUP_UNAVAILABLE(context, name);
+ return (*pkey_out != NULL) ? 1 : 0;
+}
- plgctx->dh_4096 = decode_dh_params(&oakley_4096);
- if (plgctx->dh_4096 == NULL)
- goto cleanup;
+static krb5_error_code
+pkinit_init_dh_params(krb5_context context, pkinit_plg_crypto_context plgctx)
+{
+ int n = 0;
- retval = 0;
+ n += try_import_group(context, &oakley_1024, "MODP 2 (1024-bit)",
+ &plgctx->dh_1024);
+ n += try_import_group(context, &oakley_2048, "MODP 14 (2048-bit)",
+ &plgctx->dh_2048);
+ n += try_import_group(context, &oakley_4096, "MODP 16 (4096-bit)",
+ &plgctx->dh_4096);
-cleanup:
- if (retval)
+ if (n == 0) {
pkinit_fini_dh_params(plgctx);
+ k5_setmsg(context, ENOMEM,
+ _("PKINIT cannot initialize any key exchange groups"));
+ return ENOMEM;
+ }
- return retval;
+ return 0;
}
static void
@@ -2910,11 +2918,11 @@ client_create_dh(krb5_context context,
if (cryptoctx->received_params != NULL)
params = cryptoctx->received_params;
- else if (dh_size == 1024)
+ else if (plg_cryptoctx->dh_1024 != NULL && dh_size == 1024)
params = plg_cryptoctx->dh_1024;
- else if (dh_size == 2048)
+ else if (plg_cryptoctx->dh_2048 != NULL && dh_size == 2048)
params = plg_cryptoctx->dh_2048;
- else if (dh_size == 4096)
+ else if (plg_cryptoctx->dh_4096 != NULL && dh_size == 4096)
params = plg_cryptoctx->dh_4096;
else
goto cleanup;
@@ -3210,19 +3218,23 @@ pkinit_create_td_dh_parameters(krb5_context context,
krb5_algorithm_identifier alg_4096 = { dh_oid, oakley_4096 };
krb5_algorithm_identifier *alglist[4];
- if (opts->dh_min_bits > 4096) {
- ret = KRB5KRB_ERR_GENERIC;
- goto cleanup;
- }
-
i = 0;
- if (opts->dh_min_bits <= 2048)
+ if (plg_cryptoctx->dh_2048 != NULL && opts->dh_min_bits <= 2048)
alglist[i++] = &alg_2048;
- alglist[i++] = &alg_4096;
- if (opts->dh_min_bits <= 1024)
+ if (plg_cryptoctx->dh_4096 != NULL && opts->dh_min_bits <= 4096)
+ alglist[i++] = &alg_4096;
+ if (plg_cryptoctx->dh_1024 != NULL && opts->dh_min_bits <= 1024)
alglist[i++] = &alg_1024;
alglist[i] = NULL;
+ if (i == 0) {
+ ret = KRB5KRB_ERR_GENERIC;
+ k5_setmsg(context, ret,
+ _("OpenSSL has no supported key exchange groups for "
+ "pkinit_dh_min_bits=%d"), opts->dh_min_bits);
+ goto cleanup;
+ }
+
ret = k5int_encode_krb5_td_dh_parameters(alglist, &der_alglist);
if (ret)
goto cleanup;
diff --git a/src/plugins/preauth/pkinit/pkinit_srv.c b/src/plugins/preauth/pkinit/pkinit_srv.c
index 1b3bf6d4d0..768a4e559f 100644
--- a/src/plugins/preauth/pkinit/pkinit_srv.c
+++ b/src/plugins/preauth/pkinit/pkinit_srv.c
@@ -1222,7 +1222,7 @@ pkinit_server_plugin_init_realm(krb5_context context, const char *realmname,
goto errout;
plgctx->realmname_len = strlen(plgctx->realmname);
- retval = pkinit_init_plg_crypto(&plgctx->cryptoctx);
+ retval = pkinit_init_plg_crypto(context, &plgctx->cryptoctx);
if (retval)
goto errout;
diff --git a/src/plugins/preauth/pkinit/pkinit_trace.h b/src/plugins/preauth/pkinit/pkinit_trace.h
index 259e95c6c2..5ee39c085c 100644
--- a/src/plugins/preauth/pkinit/pkinit_trace.h
+++ b/src/plugins/preauth/pkinit/pkinit_trace.h
@@ -90,6 +90,9 @@
#define TRACE_PKINIT_CLIENT_TRYAGAIN(c) \
TRACE(c, "PKINIT client trying again with KDC-provided parameters")
+#define TRACE_PKINIT_DH_GROUP_UNAVAILABLE(c, name) \
+ TRACE(c, "PKINIT key exchange group {str} unsupported", name)
+
#define TRACE_PKINIT_OPENSSL_ERROR(c, msg) \
TRACE(c, "PKINIT OpenSSL error: {str}", msg)
--
2.41.0