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From 396ce77f48f758efa090aadd00cd7208e7e97491 Mon Sep 17 00:00:00 2001
From: Robbie Harwood <rharwood@redhat.com>
Date: Fri, 15 Nov 2019 20:05:16 +0000
Subject: [PATCH] [rhel] Use backported version of OpenSSL-3 KDF interface
(cherry picked from commit 0e20daf7ccfe50518c89735c3dae2fde08d92325)
---
src/configure.ac | 4 +
src/lib/crypto/krb/derive.c | 356 +++++++++++++-----
.../preauth/pkinit/pkinit_crypto_openssl.c | 257 ++++++++-----
3 files changed, 428 insertions(+), 189 deletions(-)
diff --git a/src/configure.ac b/src/configure.ac
index d4e4da525..29be532cb 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -282,6 +282,10 @@ AC_SUBST(CRYPTO_IMPL)
AC_SUBST(CRYPTO_IMPL_CFLAGS)
AC_SUBST(CRYPTO_IMPL_LIBS)
+AC_CHECK_FUNCS(EVP_KDF_CTX_new_id EVP_KDF_ctrl EVP_KDF_derive,
+ AC_DEFINE(OSSL_KDFS, 1, [Define if using OpenSSL KDFs]),
+ AC_MSG_ERROR([backported OpenSSL KDFs not found]))
+
AC_ARG_WITH([prng-alg],
AC_HELP_STRING([--with-prng-alg=ALG], [use specified PRNG algorithm. @<:@fortuna@:>@]),
[PRNG_ALG=$withval
diff --git a/src/lib/crypto/krb/derive.c b/src/lib/crypto/krb/derive.c
index 6707a7308..915a173dd 100644
--- a/src/lib/crypto/krb/derive.c
+++ b/src/lib/crypto/krb/derive.c
@@ -27,6 +27,13 @@
#include "crypto_int.h"
+#ifdef OSSL_KDFS
+#include <openssl/evp.h>
+#include <openssl/kdf.h>
+#else
+#error "Refusing to build without OpenSSL KDFs!"
+#endif
+
static krb5_key
find_cached_dkey(struct derived_key *list, const krb5_data *constant)
{
@@ -77,55 +84,193 @@ cleanup:
return ENOMEM;
}
+#ifdef OSSL_KDFS
static krb5_error_code
-derive_random_rfc3961(const struct krb5_enc_provider *enc,
- krb5_key inkey, krb5_data *outrnd,
- const krb5_data *in_constant)
+openssl_kbdkf_counter_hmac(const struct krb5_hash_provider *hash,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *label, const krb5_data *context)
{
- size_t blocksize, keybytes, n;
+ krb5_error_code ret = KRB5_CRYPTO_INTERNAL;
+ EVP_KDF_CTX *ctx = NULL;
+ const EVP_MD *digest;
+
+ if (!strcmp(hash->hash_name, "SHA1"))
+ digest = EVP_sha1();
+ else if (!strcmp(hash->hash_name, "SHA-256"))
+ digest = EVP_sha256();
+ else if (!strcmp(hash->hash_name, "SHA-384"))
+ digest = EVP_sha384();
+ else
+ goto done;
+
+ ctx = EVP_KDF_CTX_new_id(EVP_KDF_KB);
+ if (!ctx)
+ goto done;
+
+ if (EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_MD, digest) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KB_MAC_TYPE,
+ EVP_KDF_KB_MAC_TYPE_HMAC) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KEY, inkey->keyblock.contents,
+ inkey->keyblock.length) != 1 ||
+ (context->length > 0 &&
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KB_INFO, context->data,
+ context->length) != 1) ||
+ (label->length > 0 &&
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_SALT, label->data,
+ label->length) != 1) ||
+ EVP_KDF_derive(ctx, (unsigned char *)outrnd->data,
+ outrnd->length) != 1)
+ goto done;
+
+ ret = 0;
+done:
+ if (ret)
+ zap(outrnd->data, outrnd->length);
+ EVP_KDF_CTX_free(ctx);
+ return ret;
+}
+
+static krb5_error_code
+openssl_kbkdf_feedback_cmac(const struct krb5_enc_provider *enc,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *in_constant)
+{
+ krb5_error_code ret = KRB5_CRYPTO_INTERNAL;
+ EVP_KDF_CTX *ctx = NULL;
+ const EVP_CIPHER *cipher;
+ static unsigned char zeroes[16];
+
+ memset(zeroes, 0, sizeof(zeroes));
+
+ if (enc->keylength == 16)
+ cipher = EVP_camellia_128_cbc();
+ else if (enc->keylength == 32)
+ cipher = EVP_camellia_256_cbc();
+ else
+ goto done;
+
+ ctx = EVP_KDF_CTX_new_id(EVP_KDF_KB);
+ if (!ctx)
+ goto done;
+
+ if (EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KB_MODE,
+ EVP_KDF_KB_MODE_FEEDBACK) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KB_MAC_TYPE,
+ EVP_KDF_KB_MAC_TYPE_CMAC) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_CIPHER, cipher) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KEY, inkey->keyblock.contents,
+ inkey->keyblock.length) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_SALT, in_constant->data,
+ in_constant->length) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KB_SEED, zeroes,
+ sizeof(zeroes)) != 1 ||
+ EVP_KDF_derive(ctx, (unsigned char *)outrnd->data,
+ outrnd->length) != 1)
+ goto done;
+
+ ret = 0;
+done:
+ if (ret)
+ zap(outrnd->data, outrnd->length);
+ EVP_KDF_CTX_free(ctx);
+ return ret;
+}
+
+static krb5_error_code
+openssl_krb5kdf(const struct krb5_enc_provider *enc, krb5_key inkey,
+ krb5_data *outrnd, const krb5_data *in_constant)
+{
+ krb5_error_code ret = KRB5_CRYPTO_INTERNAL;
+ EVP_KDF_CTX *ctx = NULL;
+ const EVP_CIPHER *cipher;
+
+ if (inkey->keyblock.length != enc->keylength ||
+ outrnd->length != enc->keybytes) {
+ return KRB5_CRYPTO_INTERNAL;
+ }
+
+ if (enc->encrypt == krb5int_aes_encrypt && enc->keylength == 16)
+ cipher = EVP_aes_128_cbc();
+ else if (enc->encrypt == krb5int_aes_encrypt && enc->keylength == 32)
+ cipher = EVP_aes_256_cbc();
+ else if (enc->keylength == 24)
+ cipher = EVP_des_ede3_cbc();
+ else
+ goto done;
+
+ ctx = EVP_KDF_CTX_new_id(EVP_KDF_KRB5KDF);
+ if (ctx == NULL)
+ goto done;
+
+ if (EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_CIPHER, cipher) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KEY, inkey->keyblock.contents,
+ inkey->keyblock.length) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KRB5KDF_CONSTANT,
+ in_constant->data, in_constant->length) != 1 ||
+ EVP_KDF_derive(ctx, (unsigned char *)outrnd->data,
+ outrnd->length) != 1)
+ goto done;
+
+ ret = 0;
+done:
+ if (ret)
+ zap(outrnd->data, outrnd->length);
+ EVP_KDF_CTX_free(ctx);
+ return ret;
+}
+
+#else /* OSSL_KDFS */
+
+/*
+ * NIST SP800-108 KDF in counter mode (section 5.1).
+ * Parameters:
+ * - HMAC (with hash as the hash provider) is the PRF.
+ * - A block counter of four bytes is used.
+ * - Four bytes are used to encode the output length in the PRF input.
+ *
+ * There are no uses requiring more than a single PRF invocation.
+ */
+static krb5_error_code
+builtin_sp800_108_counter_hmac(const struct krb5_hash_provider *hash,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *label,
+ const krb5_data *context)
+{
+ krb5_crypto_iov iov[5];
krb5_error_code ret;
- krb5_data block = empty_data();
+ krb5_data prf;
+ unsigned char ibuf[4], lbuf[4];
- blocksize = enc->block_size;
- keybytes = enc->keybytes;
-
- if (blocksize == 1)
- return KRB5_BAD_ENCTYPE;
- if (inkey->keyblock.length != enc->keylength || outrnd->length != keybytes)
+ if (hash == NULL || outrnd->length > hash->hashsize)
return KRB5_CRYPTO_INTERNAL;
/* Allocate encryption data buffer. */
- ret = alloc_data(&block, blocksize);
+ ret = alloc_data(&prf, hash->hashsize);
if (ret)
return ret;
- /* Initialize the input block. */
- if (in_constant->length == blocksize) {
- memcpy(block.data, in_constant->data, blocksize);
- } else {
- krb5int_nfold(in_constant->length * 8,
- (unsigned char *) in_constant->data,
- blocksize * 8, (unsigned char *) block.data);
- }
+ /* [i]2: four-byte big-endian binary string giving the block counter (1) */
+ iov[0].flags = KRB5_CRYPTO_TYPE_DATA;
+ iov[0].data = make_data(ibuf, sizeof(ibuf));
+ store_32_be(1, ibuf);
+ /* Label */
+ iov[1].flags = KRB5_CRYPTO_TYPE_DATA;
+ iov[1].data = *label;
+ /* 0x00: separator byte */
+ iov[2].flags = KRB5_CRYPTO_TYPE_DATA;
+ iov[2].data = make_data("", 1);
+ /* Context */
+ iov[3].flags = KRB5_CRYPTO_TYPE_DATA;
+ iov[3].data = *context;
+ /* [L]2: four-byte big-endian binary string giving the output length */
+ iov[4].flags = KRB5_CRYPTO_TYPE_DATA;
+ iov[4].data = make_data(lbuf, sizeof(lbuf));
+ store_32_be(outrnd->length * 8, lbuf);
- /* Loop encrypting the blocks until enough key bytes are generated. */
- n = 0;
- while (n < keybytes) {
- ret = encrypt_block(enc, inkey, &block);
- if (ret)
- goto cleanup;
-
- if ((keybytes - n) <= blocksize) {
- memcpy(outrnd->data + n, block.data, (keybytes - n));
- break;
- }
-
- memcpy(outrnd->data + n, block.data, blocksize);
- n += blocksize;
- }
-
-cleanup:
- zapfree(block.data, blocksize);
+ ret = krb5int_hmac(hash, inkey, iov, 5, &prf);
+ if (!ret)
+ memcpy(outrnd->data, prf.data, outrnd->length);
+ zapfree(prf.data, prf.length);
return ret;
}
@@ -139,9 +284,9 @@ cleanup:
* - Four bytes are used to encode the output length in the PRF input.
*/
static krb5_error_code
-derive_random_sp800_108_feedback_cmac(const struct krb5_enc_provider *enc,
- krb5_key inkey, krb5_data *outrnd,
- const krb5_data *in_constant)
+builtin_sp800_108_feedback_cmac(const struct krb5_enc_provider *enc,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *in_constant)
{
size_t blocksize, keybytes, n;
krb5_crypto_iov iov[6];
@@ -204,56 +349,94 @@ cleanup:
return ret;
}
-/*
- * NIST SP800-108 KDF in counter mode (section 5.1).
- * Parameters:
- * - HMAC (with hash as the hash provider) is the PRF.
- * - A block counter of four bytes is used.
- * - Four bytes are used to encode the output length in the PRF input.
- *
- * There are no uses requiring more than a single PRF invocation.
- */
+static krb5_error_code
+builtin_derive_random_rfc3961(const struct krb5_enc_provider *enc,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *in_constant)
+{
+ size_t blocksize, keybytes, n;
+ krb5_error_code ret;
+ krb5_data block = empty_data();
+
+ blocksize = enc->block_size;
+ keybytes = enc->keybytes;
+
+ if (blocksize == 1)
+ return KRB5_BAD_ENCTYPE;
+ if (inkey->keyblock.length != enc->keylength || outrnd->length != keybytes)
+ return KRB5_CRYPTO_INTERNAL;
+
+ /* Allocate encryption data buffer. */
+ ret = alloc_data(&block, blocksize);
+ if (ret)
+ return ret;
+
+ /* Initialize the input block. */
+ if (in_constant->length == blocksize) {
+ memcpy(block.data, in_constant->data, blocksize);
+ } else {
+ krb5int_nfold(in_constant->length * 8,
+ (unsigned char *) in_constant->data,
+ blocksize * 8, (unsigned char *) block.data);
+ }
+
+ /* Loop encrypting the blocks until enough key bytes are generated. */
+ n = 0;
+ while (n < keybytes) {
+ ret = encrypt_block(enc, inkey, &block);
+ if (ret)
+ goto cleanup;
+
+ if ((keybytes - n) <= blocksize) {
+ memcpy(outrnd->data + n, block.data, (keybytes - n));
+ break;
+ }
+
+ memcpy(outrnd->data + n, block.data, blocksize);
+ n += blocksize;
+ }
+
+cleanup:
+ zapfree(block.data, blocksize);
+ return ret;
+}
+#endif /* OSSL_KDFS */
+
krb5_error_code
k5_sp800_108_counter_hmac(const struct krb5_hash_provider *hash,
krb5_key inkey, krb5_data *outrnd,
const krb5_data *label, const krb5_data *context)
{
- krb5_crypto_iov iov[5];
- krb5_error_code ret;
- krb5_data prf;
- unsigned char ibuf[4], lbuf[4];
+#ifdef OSSL_KDFS
+ return openssl_kbdkf_counter_hmac(hash, inkey, outrnd, label, context);
+#else
+ return builtin_sp800_108_counter_hmac(hash, inkey, outrnd, label,
+ context);
+#endif
+}
- if (hash == NULL || outrnd->length > hash->hashsize)
- return KRB5_CRYPTO_INTERNAL;
+static krb5_error_code
+k5_sp800_108_feedback_cmac(const struct krb5_enc_provider *enc,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *in_constant)
+{
+#ifdef OSSL_KDFS
+ return openssl_kbkdf_feedback_cmac(enc, inkey, outrnd, in_constant);
+#else
+ return builtin_sp800_108_feedback_cmac(enc, inkey, outrnd, in_constant);
+#endif
+}
- /* Allocate encryption data buffer. */
- ret = alloc_data(&prf, hash->hashsize);
- if (ret)
- return ret;
-
- /* [i]2: four-byte big-endian binary string giving the block counter (1) */
- iov[0].flags = KRB5_CRYPTO_TYPE_DATA;
- iov[0].data = make_data(ibuf, sizeof(ibuf));
- store_32_be(1, ibuf);
- /* Label */
- iov[1].flags = KRB5_CRYPTO_TYPE_DATA;
- iov[1].data = *label;
- /* 0x00: separator byte */
- iov[2].flags = KRB5_CRYPTO_TYPE_DATA;
- iov[2].data = make_data("", 1);
- /* Context */
- iov[3].flags = KRB5_CRYPTO_TYPE_DATA;
- iov[3].data = *context;
- /* [L]2: four-byte big-endian binary string giving the output length */
- iov[4].flags = KRB5_CRYPTO_TYPE_DATA;
- iov[4].data = make_data(lbuf, sizeof(lbuf));
- store_32_be(outrnd->length * 8, lbuf);
-
- ret = krb5int_hmac(hash, inkey, iov, 5, &prf);
- if (!ret)
- memcpy(outrnd->data, prf.data, outrnd->length);
- zapfree(prf.data, prf.length);
- return ret;
+static krb5_error_code
+k5_derive_random_rfc3961(const struct krb5_enc_provider *enc,
+ krb5_key inkey, krb5_data *outrnd,
+ const krb5_data *in_constant)
+{
+#ifdef OSSL_KDFS
+ return openssl_krb5kdf(enc, inkey, outrnd, in_constant);
+#else
+ return builtin_derive_random_rfc3961(enc, inkey, outrnd, in_constant);
+#endif
}
krb5_error_code
@@ -266,10 +449,9 @@ krb5int_derive_random(const struct krb5_enc_provider *enc,
switch (alg) {
case DERIVE_RFC3961:
- return derive_random_rfc3961(enc, inkey, outrnd, in_constant);
+ return k5_derive_random_rfc3961(enc, inkey, outrnd, in_constant);
case DERIVE_SP800_108_CMAC:
- return derive_random_sp800_108_feedback_cmac(enc, inkey, outrnd,
- in_constant);
+ return k5_sp800_108_feedback_cmac(enc, inkey, outrnd, in_constant);
case DERIVE_SP800_108_HMAC:
return k5_sp800_108_counter_hmac(hash, inkey, outrnd, in_constant,
&empty);
diff --git a/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c b/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
index 52976895b..dd718c2be 100644
--- a/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
+++ b/src/plugins/preauth/pkinit/pkinit_crypto_openssl.c
@@ -38,6 +38,13 @@
#include <dirent.h>
#include <arpa/inet.h>
+#ifdef OSSL_KDFS
+#include <openssl/evp.h>
+#include <openssl/kdf.h>
+#else
+#error "Refusing to build without OpenSSL KDFs!"
+#endif
+
static krb5_error_code pkinit_init_pkinit_oids(pkinit_plg_crypto_context );
static void pkinit_fini_pkinit_oids(pkinit_plg_crypto_context );
@@ -2331,11 +2338,51 @@ pkinit_alg_values(krb5_context context,
}
} /* pkinit_alg_values() */
+#ifdef OSSL_KDFS
+static krb5_error_code
+openssl_sskdf(krb5_context context, size_t hash_bytes, krb5_data *key,
+ krb5_data *info, char *out, size_t out_len)
+{
+ krb5_error_code ret = KRB5_CRYPTO_INTERNAL;
+ EVP_KDF_CTX *ctx = NULL;
+ const EVP_MD *digest;
-/* pkinit_alg_agility_kdf() --
- * This function generates a key using the KDF described in
- * draft_ietf_krb_wg_pkinit_alg_agility-04.txt. The algorithm is
- * described as follows:
+ /* RFC 8636 defines a SHA384 variant, but we don't use it. */
+ if (hash_bytes == 20) {
+ digest = EVP_sha1();
+ } else if (hash_bytes == 32) {
+ digest = EVP_sha256();
+ } else if (hash_bytes == 64) {
+ digest = EVP_sha512();
+ } else {
+ krb5_set_error_message(context, ret, "Bad hash type for SSKDF");
+ goto done;
+ }
+
+ ctx = EVP_KDF_CTX_new_id(EVP_KDF_SS);
+ if (!ctx) {
+ oerr(context, ret, _("Failed to instantiate SSKDF"));
+ goto done;
+ }
+
+ if (EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_MD, digest) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KEY, key->data,
+ key->length) != 1 ||
+ EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_SSKDF_INFO, info->data,
+ info->length) != 1 ||
+ EVP_KDF_derive(ctx, (unsigned char *)out, out_len) != 1)
+ goto done;
+
+ ret = 0;
+done:
+ EVP_KDF_CTX_free(ctx);
+ return ret;
+}
+#else
+/*
+ * Generate a key using the KDF described in RFC 8636, also known as SSKDF
+ * (single-step kdf). Our caller precomputes `reps`, but otherwise the
+ * algorithm is as follows:
*
* 1. reps = keydatalen (K) / hash length (H)
*
@@ -2349,95 +2396,16 @@ pkinit_alg_values(krb5_context context,
*
* 4. Set key = Hash1 || Hash2 || ... so that length of key is K bytes.
*/
-krb5_error_code
-pkinit_alg_agility_kdf(krb5_context context,
- krb5_data *secret,
- krb5_data *alg_oid,
- krb5_const_principal party_u_info,
- krb5_const_principal party_v_info,
- krb5_enctype enctype,
- krb5_data *as_req,
- krb5_data *pk_as_rep,
- krb5_keyblock *key_block)
+static krb5_error_code
+builtin_sskdf(krb5_context context, unsigned int reps, size_t hash_len,
+ const EVP_MD *(*EVP_func)(void), krb5_data *secret,
+ krb5_data *other_info, char *out, size_t out_len)
{
krb5_error_code retval = 0;
- unsigned int reps = 0;
- uint32_t counter = 1; /* Does this type work on Windows? */
+ uint32_t counter = 1;
size_t offset = 0;
- size_t hash_len = 0;
- size_t rand_len = 0;
- size_t key_len = 0;
- krb5_data random_data;
- krb5_sp80056a_other_info other_info_fields;
- krb5_pkinit_supp_pub_info supp_pub_info_fields;
- krb5_data *other_info = NULL;
- krb5_data *supp_pub_info = NULL;
- krb5_algorithm_identifier alg_id;
EVP_MD_CTX *ctx = NULL;
- const EVP_MD *(*EVP_func)(void);
-
- /* initialize random_data here to make clean-up safe */
- random_data.length = 0;
- random_data.data = NULL;
-
- /* allocate and initialize the key block */
- key_block->magic = 0;
- key_block->enctype = enctype;
- if (0 != (retval = krb5_c_keylengths(context, enctype, &rand_len,
- &key_len)))
- goto cleanup;
-
- random_data.length = rand_len;
- key_block->length = key_len;
-
- if (NULL == (key_block->contents = malloc(key_block->length))) {
- retval = ENOMEM;
- goto cleanup;
- }
-
- memset (key_block->contents, 0, key_block->length);
-
- /* If this is anonymous pkinit, use the anonymous principle for party_u_info */
- if (party_u_info && krb5_principal_compare_any_realm(context, party_u_info,
- krb5_anonymous_principal()))
- party_u_info = (krb5_principal)krb5_anonymous_principal();
-
- if (0 != (retval = pkinit_alg_values(context, alg_oid, &hash_len, &EVP_func)))
- goto cleanup;
-
- /* 1. reps = keydatalen (K) / hash length (H) */
- reps = key_block->length/hash_len;
-
- /* ... and round up, if necessary */
- if (key_block->length > (reps * hash_len))
- reps++;
-
- /* Allocate enough space in the random data buffer to hash directly into
- * it, even if the last hash will make it bigger than the key length. */
- if (NULL == (random_data.data = malloc(reps * hash_len))) {
- retval = ENOMEM;
- goto cleanup;
- }
-
- /* Encode the ASN.1 octet string for "SuppPubInfo" */
- supp_pub_info_fields.enctype = enctype;
- supp_pub_info_fields.as_req = *as_req;
- supp_pub_info_fields.pk_as_rep = *pk_as_rep;
- if (0 != ((retval = encode_krb5_pkinit_supp_pub_info(&supp_pub_info_fields,
- &supp_pub_info))))
- goto cleanup;
-
- /* Now encode the ASN.1 octet string for "OtherInfo" */
- memset(&alg_id, 0, sizeof alg_id);
- alg_id.algorithm = *alg_oid; /*alias*/
-
- other_info_fields.algorithm_identifier = alg_id;
- other_info_fields.party_u_info = (krb5_principal) party_u_info;
- other_info_fields.party_v_info = (krb5_principal) party_v_info;
- other_info_fields.supp_pub_info = *supp_pub_info;
- if (0 != (retval = encode_krb5_sp80056a_other_info(&other_info_fields, &other_info)))
- goto cleanup;
/* 2. Initialize a 32-bit, big-endian bit string counter as 1.
* 3. For i = 1 to reps by 1, do the following:
@@ -2471,8 +2439,9 @@ pkinit_alg_agility_kdf(krb5_context context,
goto cleanup;
}
- /* 4. Set key = Hash1 || Hash2 || ... so that length of key is K bytes. */
- if (!EVP_DigestFinal(ctx, (uint8_t *)random_data.data + offset, &s)) {
+ /* 4. Set key = Hash1 || Hash2 || ... so that length of key is K
+ * bytes. */
+ if (!EVP_DigestFinal(ctx, (unsigned char *)out + offset, &s)) {
krb5_set_error_message(context, KRB5_CRYPTO_INTERNAL,
"Call to OpenSSL EVP_DigestUpdate() returned an error.");
retval = KRB5_CRYPTO_INTERNAL;
@@ -2484,26 +2453,110 @@ pkinit_alg_agility_kdf(krb5_context context,
EVP_MD_CTX_free(ctx);
ctx = NULL;
}
-
- retval = krb5_c_random_to_key(context, enctype, &random_data,
- key_block);
-
cleanup:
EVP_MD_CTX_free(ctx);
+ return retval;
+} /* builtin_sskdf() */
+#endif /* OSSL_KDFS */
- /* If this has been an error, free the allocated key_block, if any */
- if (retval) {
- krb5_free_keyblock_contents(context, key_block);
+/* id-pkinit-kdf family, as specified by RFC 8636. */
+krb5_error_code
+pkinit_alg_agility_kdf(krb5_context context, krb5_data *secret,
+ krb5_data *alg_oid, krb5_const_principal party_u_info,
+ krb5_const_principal party_v_info,
+ krb5_enctype enctype, krb5_data *as_req,
+ krb5_data *pk_as_rep, krb5_keyblock *key_block)
+{
+ krb5_error_code retval;
+ size_t hash_len = 0, rand_len = 0, key_len = 0;
+ const EVP_MD *(*EVP_func)(void);
+ krb5_sp80056a_other_info other_info_fields;
+ krb5_pkinit_supp_pub_info supp_pub_info_fields;
+ krb5_data *other_info = NULL, *supp_pub_info = NULL;
+ krb5_data random_data = empty_data();
+ krb5_algorithm_identifier alg_id;
+ unsigned int reps;
+
+ /* Allocate and initialize the key block. */
+ key_block->magic = 0;
+ key_block->enctype = enctype;
+
+ /* Use separate variables to avoid alignment restriction problems. */
+ retval = krb5_c_keylengths(context, enctype, &rand_len, &key_len);
+ if (retval)
+ goto cleanup;
+ random_data.length = rand_len;
+ key_block->length = key_len;
+
+ key_block->contents = k5calloc(key_block->length, 1, &retval);
+ if (key_block->contents == NULL)
+ goto cleanup;
+
+ /* If this is anonymous pkinit, use the anonymous principle for
+ * party_u_info. */
+ if (party_u_info &&
+ krb5_principal_compare_any_realm(context, party_u_info,
+ krb5_anonymous_principal())) {
+ party_u_info = (krb5_principal)krb5_anonymous_principal();
}
- /* free other allocated resources, either way */
- if (random_data.data)
- free(random_data.data);
+ retval = pkinit_alg_values(context, alg_oid, &hash_len, &EVP_func);
+ if (retval)
+ goto cleanup;
+
+ /* 1. reps = keydatalen (K) / hash length (H) */
+ reps = key_block->length / hash_len;
+
+ /* ... and round up, if necessary. */
+ if (key_block->length > (reps * hash_len))
+ reps++;
+
+ /* Allocate enough space in the random data buffer to hash directly into
+ * it, even if the last hash will make it bigger than the key length. */
+ random_data.data = k5alloc(reps * hash_len, &retval);
+ if (random_data.data == NULL)
+ goto cleanup;
+
+ /* Encode the ASN.1 octet string for "SuppPubInfo". */
+ supp_pub_info_fields.enctype = enctype;
+ supp_pub_info_fields.as_req = *as_req;
+ supp_pub_info_fields.pk_as_rep = *pk_as_rep;
+ retval = encode_krb5_pkinit_supp_pub_info(&supp_pub_info_fields,
+ &supp_pub_info);
+ if (retval)
+ goto cleanup;
+
+ /* Now encode the ASN.1 octet string for "OtherInfo". */
+ memset(&alg_id, 0, sizeof(alg_id));
+ alg_id.algorithm = *alg_oid;
+ other_info_fields.algorithm_identifier = alg_id;
+ other_info_fields.party_u_info = (krb5_principal)party_u_info;
+ other_info_fields.party_v_info = (krb5_principal)party_v_info;
+ other_info_fields.supp_pub_info = *supp_pub_info;
+ retval = encode_krb5_sp80056a_other_info(&other_info_fields, &other_info);
+ if (retval)
+ goto cleanup;
+
+#ifdef OSSL_KDFS
+ retval = openssl_sskdf(context, hash_len, secret, other_info,
+ random_data.data, key_block->length);
+#else
+ retval = builtin_sskdf(context, reps, hash_len, EVP_func, secret,
+ other_info, random_data.data, key_block->length);
+#endif
+ if (retval)
+ goto cleanup;
+
+ retval = krb5_c_random_to_key(context, enctype, &random_data, key_block);
+cleanup:
+ if (retval)
+ krb5_free_keyblock_contents(context, key_block);
+
+ zapfree(random_data.data, random_data.length);
krb5_free_data(context, other_info);
krb5_free_data(context, supp_pub_info);
-
return retval;
-} /*pkinit_alg_agility_kdf() */
+}
/* Call DH_compute_key() and ensure that we left-pad short results instead of
* leaving junk bytes at the end of the buffer. */
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