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      1 /*
      2  * Copyright 2018-2024 The OpenSSL Project Authors. All Rights Reserved.
      3  *
      4  * Licensed under the Apache License 2.0 (the "License").  You may not use
      5  * this file except in compliance with the License.  You can obtain a copy
      6  * in the file LICENSE in the source distribution or at
      7  * https://www.openssl.org/source/license.html
      8  */
      9 
     10 #include <stdlib.h>
     11 #include <stdarg.h>
     12 #include <string.h>
     13 #include <openssl/evp.h>
     14 #include <openssl/kdf.h>
     15 #include <openssl/core_names.h>
     16 #include <openssl/proverr.h>
     17 #include "internal/cryptlib.h"
     18 #include "internal/numbers.h"
     19 #include "crypto/evp.h"
     20 #include "prov/provider_ctx.h"
     21 #include "prov/providercommon.h"
     22 #include "prov/implementations.h"
     23 #include "prov/provider_util.h"
     24 #include "prov/securitycheck.h"
     25 
     26 /* See RFC 4253, Section 7.2 */
     27 static OSSL_FUNC_kdf_newctx_fn kdf_sshkdf_new;
     28 static OSSL_FUNC_kdf_dupctx_fn kdf_sshkdf_dup;
     29 static OSSL_FUNC_kdf_freectx_fn kdf_sshkdf_free;
     30 static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
     31 static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
     32 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
     33 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
     34 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
     35 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
     36 
     37 static int SSHKDF(const EVP_MD *evp_md,
     38     const unsigned char *key, size_t key_len,
     39     const unsigned char *xcghash, size_t xcghash_len,
     40     const unsigned char *session_id, size_t session_id_len,
     41     char type, unsigned char *okey, size_t okey_len);
     42 
     43 typedef struct {
     44     void *provctx;
     45     PROV_DIGEST digest;
     46     unsigned char *key; /* K */
     47     size_t key_len;
     48     unsigned char *xcghash; /* H */
     49     size_t xcghash_len;
     50     char type; /* X */
     51     unsigned char *session_id;
     52     size_t session_id_len;
     53     OSSL_FIPS_IND_DECLARE
     54 } KDF_SSHKDF;
     55 
     56 static void *kdf_sshkdf_new(void *provctx)
     57 {
     58     KDF_SSHKDF *ctx;
     59 
     60     if (!ossl_prov_is_running())
     61         return NULL;
     62 
     63     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL) {
     64         ctx->provctx = provctx;
     65         OSSL_FIPS_IND_INIT(ctx)
     66     }
     67     return ctx;
     68 }
     69 
     70 static void kdf_sshkdf_free(void *vctx)
     71 {
     72     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
     73 
     74     if (ctx != NULL) {
     75         kdf_sshkdf_reset(ctx);
     76         OPENSSL_free(ctx);
     77     }
     78 }
     79 
     80 static void kdf_sshkdf_reset(void *vctx)
     81 {
     82     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
     83     void *provctx = ctx->provctx;
     84 
     85     ossl_prov_digest_reset(&ctx->digest);
     86     OPENSSL_clear_free(ctx->key, ctx->key_len);
     87     OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
     88     OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
     89     memset(ctx, 0, sizeof(*ctx));
     90     ctx->provctx = provctx;
     91 }
     92 
     93 static void *kdf_sshkdf_dup(void *vctx)
     94 {
     95     const KDF_SSHKDF *src = (const KDF_SSHKDF *)vctx;
     96     KDF_SSHKDF *dest;
     97 
     98     dest = kdf_sshkdf_new(src->provctx);
     99     if (dest != NULL) {
    100         if (!ossl_prov_memdup(src->key, src->key_len,
    101                 &dest->key, &dest->key_len)
    102             || !ossl_prov_memdup(src->xcghash, src->xcghash_len,
    103                 &dest->xcghash, &dest->xcghash_len)
    104             || !ossl_prov_memdup(src->session_id, src->session_id_len,
    105                 &dest->session_id, &dest->session_id_len)
    106             || !ossl_prov_digest_copy(&dest->digest, &src->digest))
    107             goto err;
    108         dest->type = src->type;
    109         OSSL_FIPS_IND_COPY(dest, src)
    110     }
    111     return dest;
    112 
    113 err:
    114     kdf_sshkdf_free(dest);
    115     return NULL;
    116 }
    117 
    118 static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
    119     const OSSL_PARAM *p)
    120 {
    121     OPENSSL_clear_free(*dst, *dst_len);
    122     *dst = NULL;
    123     *dst_len = 0;
    124     return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
    125 }
    126 
    127 #ifdef FIPS_MODULE
    128 static int fips_digest_check_passed(KDF_SSHKDF *ctx, const EVP_MD *md)
    129 {
    130     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
    131     /*
    132      * Perform digest check
    133      *
    134      * According to NIST SP 800-135r1 section 5.2, the valid hash functions are
    135      * specified in FIPS 180-3. ACVP also only lists the same set of hash
    136      * functions.
    137      */
    138     int digest_unapproved = !EVP_MD_is_a(md, SN_sha1)
    139         && !EVP_MD_is_a(md, SN_sha224)
    140         && !EVP_MD_is_a(md, SN_sha256)
    141         && !EVP_MD_is_a(md, SN_sha384)
    142         && !EVP_MD_is_a(md, SN_sha512);
    143 
    144     if (digest_unapproved) {
    145         if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE0,
    146                 libctx, "SSHKDF", "Digest",
    147                 ossl_fips_config_sshkdf_digest_check)) {
    148             ERR_raise(ERR_LIB_PROV, PROV_R_DIGEST_NOT_ALLOWED);
    149             return 0;
    150         }
    151     }
    152     return 1;
    153 }
    154 
    155 static int fips_key_check_passed(KDF_SSHKDF *ctx)
    156 {
    157     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
    158     int key_approved = ossl_kdf_check_key_size(ctx->key_len);
    159 
    160     if (!key_approved) {
    161         if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE1,
    162                 libctx, "SSHKDF", "Key size",
    163                 ossl_fips_config_sshkdf_key_check)) {
    164             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
    165             return 0;
    166         }
    167     }
    168     return 1;
    169 }
    170 #endif
    171 
    172 static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen,
    173     const OSSL_PARAM params[])
    174 {
    175     KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
    176     const EVP_MD *md;
    177 
    178     if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params))
    179         return 0;
    180 
    181     md = ossl_prov_digest_md(&ctx->digest);
    182     if (md == NULL) {
    183         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
    184         return 0;
    185     }
    186     if (ctx->key == NULL) {
    187         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
    188         return 0;
    189     }
    190     if (ctx->xcghash == NULL) {
    191         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
    192         return 0;
    193     }
    194     if (ctx->session_id == NULL) {
    195         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
    196         return 0;
    197     }
    198     if (ctx->type == 0) {
    199         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
    200         return 0;
    201     }
    202 
    203     return SSHKDF(md, ctx->key, ctx->key_len,
    204         ctx->xcghash, ctx->xcghash_len,
    205         ctx->session_id, ctx->session_id_len,
    206         ctx->type, key, keylen);
    207 }
    208 
    209 static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
    210 {
    211     const OSSL_PARAM *p;
    212     KDF_SSHKDF *ctx = vctx;
    213     OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
    214 
    215     if (ossl_param_is_empty(params))
    216         return 1;
    217 
    218     if (!OSSL_FIPS_IND_SET_CTX_PARAM(ctx, OSSL_FIPS_IND_SETTABLE0, params,
    219             OSSL_KDF_PARAM_FIPS_DIGEST_CHECK))
    220         return 0;
    221     if (!OSSL_FIPS_IND_SET_CTX_PARAM(ctx, OSSL_FIPS_IND_SETTABLE1, params,
    222             OSSL_KDF_PARAM_FIPS_KEY_CHECK))
    223         return 0;
    224 
    225     if (OSSL_PARAM_locate_const(params, OSSL_ALG_PARAM_DIGEST) != NULL) {
    226         const EVP_MD *md = NULL;
    227 
    228         if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
    229             return 0;
    230 
    231         md = ossl_prov_digest_md(&ctx->digest);
    232         if (EVP_MD_xof(md)) {
    233             ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
    234             return 0;
    235         }
    236 
    237 #ifdef FIPS_MODULE
    238         if (!fips_digest_check_passed(ctx, md))
    239             return 0;
    240 #endif
    241     }
    242 
    243     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
    244         if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
    245             return 0;
    246 
    247 #ifdef FIPS_MODULE
    248         if (!fips_key_check_passed(ctx))
    249             return 0;
    250 #endif
    251     }
    252 
    253     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
    254         != NULL)
    255         if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
    256             return 0;
    257 
    258     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
    259         != NULL)
    260         if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
    261             return 0;
    262 
    263     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
    264         != NULL) {
    265         const char *kdftype;
    266 
    267         if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
    268             return 0;
    269         /* Expect one character (byte in this case) */
    270         if (kdftype == NULL || p->data_size != 1)
    271             return 0;
    272         if (kdftype[0] < 65 || kdftype[0] > 70) {
    273             ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
    274             return 0;
    275         }
    276         ctx->type = kdftype[0];
    277     }
    278     return 1;
    279 }
    280 
    281 static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
    282     ossl_unused void *p_ctx)
    283 {
    284     static const OSSL_PARAM known_settable_ctx_params[] = {
    285         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
    286         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
    287         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
    288         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
    289         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
    290         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
    291         OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_KDF_PARAM_FIPS_DIGEST_CHECK)
    292             OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_KDF_PARAM_FIPS_KEY_CHECK)
    293                 OSSL_PARAM_END
    294     };
    295     return known_settable_ctx_params;
    296 }
    297 
    298 static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
    299 {
    300     OSSL_PARAM *p;
    301 
    302     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL) {
    303         if (!OSSL_PARAM_set_size_t(p, SIZE_MAX))
    304             return 0;
    305     }
    306     if (!OSSL_FIPS_IND_GET_CTX_PARAM(((KDF_SSHKDF *)vctx), params))
    307         return 0;
    308     return 1;
    309 }
    310 
    311 static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
    312     ossl_unused void *p_ctx)
    313 {
    314     static const OSSL_PARAM known_gettable_ctx_params[] = {
    315         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
    316         OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
    317             OSSL_PARAM_END
    318     };
    319     return known_gettable_ctx_params;
    320 }
    321 
    322 const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
    323     { OSSL_FUNC_KDF_NEWCTX, (void (*)(void))kdf_sshkdf_new },
    324     { OSSL_FUNC_KDF_DUPCTX, (void (*)(void))kdf_sshkdf_dup },
    325     { OSSL_FUNC_KDF_FREECTX, (void (*)(void))kdf_sshkdf_free },
    326     { OSSL_FUNC_KDF_RESET, (void (*)(void))kdf_sshkdf_reset },
    327     { OSSL_FUNC_KDF_DERIVE, (void (*)(void))kdf_sshkdf_derive },
    328     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
    329         (void (*)(void))kdf_sshkdf_settable_ctx_params },
    330     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void (*)(void))kdf_sshkdf_set_ctx_params },
    331     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
    332         (void (*)(void))kdf_sshkdf_gettable_ctx_params },
    333     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void (*)(void))kdf_sshkdf_get_ctx_params },
    334     OSSL_DISPATCH_END
    335 };
    336 
    337 static int SSHKDF(const EVP_MD *evp_md,
    338     const unsigned char *key, size_t key_len,
    339     const unsigned char *xcghash, size_t xcghash_len,
    340     const unsigned char *session_id, size_t session_id_len,
    341     char type, unsigned char *okey, size_t okey_len)
    342 {
    343     EVP_MD_CTX *md = NULL;
    344     unsigned char digest[EVP_MAX_MD_SIZE];
    345     unsigned int dsize = 0;
    346     size_t cursize = 0;
    347     int ret = 0;
    348 
    349     md = EVP_MD_CTX_new();
    350     if (md == NULL)
    351         return 0;
    352 
    353     if (!EVP_DigestInit_ex(md, evp_md, NULL))
    354         goto out;
    355 
    356     if (!EVP_DigestUpdate(md, key, key_len))
    357         goto out;
    358 
    359     if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
    360         goto out;
    361 
    362     if (!EVP_DigestUpdate(md, &type, 1))
    363         goto out;
    364 
    365     if (!EVP_DigestUpdate(md, session_id, session_id_len))
    366         goto out;
    367 
    368     if (!EVP_DigestFinal_ex(md, digest, &dsize))
    369         goto out;
    370 
    371     if (okey_len < dsize) {
    372         memcpy(okey, digest, okey_len);
    373         ret = 1;
    374         goto out;
    375     }
    376 
    377     memcpy(okey, digest, dsize);
    378 
    379     for (cursize = dsize; cursize < okey_len; cursize += dsize) {
    380 
    381         if (!EVP_DigestInit_ex(md, evp_md, NULL))
    382             goto out;
    383 
    384         if (!EVP_DigestUpdate(md, key, key_len))
    385             goto out;
    386 
    387         if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
    388             goto out;
    389 
    390         if (!EVP_DigestUpdate(md, okey, cursize))
    391             goto out;
    392 
    393         if (!EVP_DigestFinal_ex(md, digest, &dsize))
    394             goto out;
    395 
    396         if (okey_len < cursize + dsize) {
    397             memcpy(okey + cursize, digest, okey_len - cursize);
    398             ret = 1;
    399             goto out;
    400         }
    401 
    402         memcpy(okey + cursize, digest, dsize);
    403     }
    404 
    405     ret = 1;
    406 
    407 out:
    408     EVP_MD_CTX_free(md);
    409     OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
    410     return ret;
    411 }
    412