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{-
10use OpenSSL::paramnames qw(produce_param_decoder);
11-}
12
13#include <stdlib.h>
14#include <stdarg.h>
15#include <string.h>
16#include <openssl/evp.h>
17#include <openssl/kdf.h>
18#include <openssl/core_names.h>
19#include <openssl/proverr.h>
20#include "internal/cryptlib.h"
21#include "internal/numbers.h"
22#include "crypto/evp.h"
23#include "prov/provider_ctx.h"
24#include "prov/providercommon.h"
25#include "prov/implementations.h"
26#include "prov/provider_util.h"
27#include "prov/securitycheck.h"
28
29/* See RFC 4253, Section 7.2 */
30static OSSL_FUNC_kdf_newctx_fn kdf_sshkdf_new;
31static OSSL_FUNC_kdf_dupctx_fn kdf_sshkdf_dup;
32static OSSL_FUNC_kdf_freectx_fn kdf_sshkdf_free;
33static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
34static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
35static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
36static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
37static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
38static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
39
40static int SSHKDF(const EVP_MD *evp_md,
41                  const unsigned char *key, size_t key_len,
42                  const unsigned char *xcghash, size_t xcghash_len,
43                  const unsigned char *session_id, size_t session_id_len,
44                  char type, unsigned char *okey, size_t okey_len);
45
46typedef struct {
47    void *provctx;
48    PROV_DIGEST digest;
49    unsigned char *key; /* K */
50    size_t key_len;
51    unsigned char *xcghash; /* H */
52    size_t xcghash_len;
53    char type; /* X */
54    unsigned char *session_id;
55    size_t session_id_len;
56    OSSL_FIPS_IND_DECLARE
57} KDF_SSHKDF;
58
59static void *kdf_sshkdf_new(void *provctx)
60{
61    KDF_SSHKDF *ctx;
62
63    if (!ossl_prov_is_running())
64        return NULL;
65
66    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL) {
67        ctx->provctx = provctx;
68        OSSL_FIPS_IND_INIT(ctx)
69    }
70    return ctx;
71}
72
73static void kdf_sshkdf_free(void *vctx)
74{
75    KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
76
77    if (ctx != NULL) {
78        kdf_sshkdf_reset(ctx);
79        OPENSSL_free(ctx);
80    }
81}
82
83static void kdf_sshkdf_reset(void *vctx)
84{
85    KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
86    void *provctx = ctx->provctx;
87
88    ossl_prov_digest_reset(&ctx->digest);
89    OPENSSL_clear_free(ctx->key, ctx->key_len);
90    OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
91    OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
92    memset(ctx, 0, sizeof(*ctx));
93    ctx->provctx = provctx;
94}
95
96static void *kdf_sshkdf_dup(void *vctx)
97{
98    const KDF_SSHKDF *src = (const KDF_SSHKDF *)vctx;
99    KDF_SSHKDF *dest;
100
101    dest = kdf_sshkdf_new(src->provctx);
102    if (dest != NULL) {
103        if (!ossl_prov_memdup(src->key, src->key_len,
104                              &dest->key, &dest->key_len)
105                || !ossl_prov_memdup(src->xcghash, src->xcghash_len,
106                                     &dest->xcghash , &dest->xcghash_len)
107                || !ossl_prov_memdup(src->session_id, src->session_id_len,
108                                     &dest->session_id , &dest->session_id_len)
109                || !ossl_prov_digest_copy(&dest->digest, &src->digest))
110            goto err;
111        dest->type = src->type;
112        OSSL_FIPS_IND_COPY(dest, src)
113    }
114    return dest;
115
116 err:
117    kdf_sshkdf_free(dest);
118    return NULL;
119}
120
121static int sshkdf_set_membuf(unsigned char **dst, size_t *dst_len,
122                             const OSSL_PARAM *p)
123{
124    OPENSSL_clear_free(*dst, *dst_len);
125    *dst = NULL;
126    *dst_len = 0;
127    return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
128}
129
130#ifdef FIPS_MODULE
131static int fips_digest_check_passed(KDF_SSHKDF *ctx, const EVP_MD *md)
132{
133    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
134    /*
135     * Perform digest check
136     *
137     * According to NIST SP 800-135r1 section 5.2, the valid hash functions are
138     * specified in FIPS 180-3. ACVP also only lists the same set of hash
139     * functions.
140     */
141    int digest_unapproved = !EVP_MD_is_a(md, SN_sha1)
142        && !EVP_MD_is_a(md, SN_sha224)
143        && !EVP_MD_is_a(md, SN_sha256)
144        && !EVP_MD_is_a(md, SN_sha384)
145        && !EVP_MD_is_a(md, SN_sha512);
146
147    if (digest_unapproved) {
148        if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE0,
149                                         libctx, "SSHKDF", "Digest",
150                                         ossl_fips_config_sshkdf_digest_check)) {
151            ERR_raise(ERR_LIB_PROV, PROV_R_DIGEST_NOT_ALLOWED);
152            return 0;
153        }
154    }
155    return 1;
156}
157
158static int fips_key_check_passed(KDF_SSHKDF *ctx)
159{
160    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
161    int key_approved = ossl_kdf_check_key_size(ctx->key_len);
162
163    if (!key_approved) {
164        if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE1,
165                                         libctx, "SSHKDF", "Key size",
166                                         ossl_fips_config_sshkdf_key_check)) {
167            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
168            return 0;
169        }
170    }
171    return 1;
172}
173#endif
174
175static int kdf_sshkdf_derive(void *vctx, unsigned char *key, size_t keylen,
176                             const OSSL_PARAM params[])
177{
178    KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
179    const EVP_MD *md;
180
181    if (!ossl_prov_is_running() || !kdf_sshkdf_set_ctx_params(ctx, params))
182        return 0;
183
184    md = ossl_prov_digest_md(&ctx->digest);
185    if (md == NULL) {
186        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
187        return 0;
188    }
189    if (ctx->key == NULL) {
190        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
191        return 0;
192    }
193    if (ctx->xcghash == NULL) {
194        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
195        return 0;
196    }
197    if (ctx->session_id == NULL) {
198        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
199        return 0;
200    }
201    if (ctx->type == 0) {
202        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
203        return 0;
204    }
205
206    return SSHKDF(md, ctx->key, ctx->key_len,
207                  ctx->xcghash, ctx->xcghash_len,
208                  ctx->session_id, ctx->session_id_len,
209                  ctx->type, key, keylen);
210}
211
212{- produce_param_decoder('sshkdf_set_ctx_params',
213                         (['KDF_PARAM_PROPERTIES',        'propq',   'utf8_string'],
214                          ['ALG_PARAM_ENGINE',            'engine',  'utf8_string', 'hidden'],
215                          ['KDF_PARAM_DIGEST',            'digest',  'utf8_string'],
216                          ['KDF_PARAM_KEY',               'key',     'octet_string'],
217                          ['KDF_PARAM_SSHKDF_XCGHASH',    'xcg',     'octet_string'],
218                          ['KDF_PARAM_SSHKDF_SESSION_ID', 'sid',     'octet_string'],
219                          ['KDF_PARAM_SSHKDF_TYPE',       'type',    'utf8_string'],
220                          ['KDF_PARAM_FIPS_DIGEST_CHECK', 'ind_d',   'int', 'fips'],
221                          ['KDF_PARAM_FIPS_KEY_CHECK',    'ind_k',   'int', 'fips'],
222                         )); -}
223
224static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
225{
226    struct sshkdf_set_ctx_params_st p;
227    KDF_SSHKDF *ctx = vctx;
228    OSSL_LIB_CTX *provctx;
229
230    if (ctx == NULL || !sshkdf_set_ctx_params_decoder(params, &p))
231        return 0;
232
233    provctx = PROV_LIBCTX_OF(ctx->provctx);
234
235    if (!OSSL_FIPS_IND_SET_CTX_FROM_PARAM(ctx, OSSL_FIPS_IND_SETTABLE0, p.ind_d))
236        return 0;
237    if (!OSSL_FIPS_IND_SET_CTX_FROM_PARAM(ctx, OSSL_FIPS_IND_SETTABLE1, p.ind_k))
238        return 0;
239
240    if (p.digest != NULL) {
241        const EVP_MD *md = NULL;
242
243        if (!ossl_prov_digest_load(&ctx->digest, p.digest,
244                                   p.propq, p.engine, provctx))
245            return 0;
246
247        md = ossl_prov_digest_md(&ctx->digest);
248        if (EVP_MD_xof(md)) {
249            ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
250            return 0;
251        }
252
253#ifdef FIPS_MODULE
254        if (!fips_digest_check_passed(ctx, md))
255            return 0;
256#endif
257    }
258
259    if (p.key != NULL) {
260        if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p.key))
261            return 0;
262
263#ifdef FIPS_MODULE
264        if (!fips_key_check_passed(ctx))
265            return 0;
266#endif
267    }
268
269    if (p.xcg != NULL
270            && !sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p.xcg))
271        return 0;
272
273    if (p.sid != NULL
274            && !sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p.sid))
275        return 0;
276
277    if (p.type != NULL) {
278        const char *kdftype;
279
280        if (!OSSL_PARAM_get_utf8_string_ptr(p.type, &kdftype))
281            return 0;
282        /* Expect one character (byte in this case) */
283        if (kdftype == NULL || p.type->data_size != 1)
284            return 0;
285        if (kdftype[0] < 65 || kdftype[0] > 70) {
286            ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
287            return 0;
288        }
289        ctx->type = kdftype[0];
290    }
291    return 1;
292}
293
294static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
295                                                        ossl_unused void *p_ctx)
296{
297    return sshkdf_set_ctx_params_list;
298}
299
300{- produce_param_decoder('sshkdf_get_ctx_params',
301                         (['KDF_PARAM_SIZE',                    'size', 'size_t'],
302                          ['KDF_PARAM_FIPS_APPROVED_INDICATOR', 'ind',  'int', 'fips'],
303                         )); -}
304
305static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
306{
307    KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
308    struct sshkdf_get_ctx_params_st p;
309
310    if (ctx == NULL || !sshkdf_get_ctx_params_decoder(params, &p))
311        return 0;
312
313    if (p.size != NULL && !OSSL_PARAM_set_size_t(p.size, SIZE_MAX))
314        return 0;
315
316    if (!OSSL_FIPS_IND_GET_CTX_FROM_PARAM(ctx, p.ind))
317        return 0;
318    return 1;
319}
320
321static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
322                                                        ossl_unused void *p_ctx)
323{
324    return sshkdf_get_ctx_params_list;
325}
326
327const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
328    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
329    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_sshkdf_dup },
330    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
331    { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
332    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
333    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
334      (void(*)(void))kdf_sshkdf_settable_ctx_params },
335    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
336    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
337      (void(*)(void))kdf_sshkdf_gettable_ctx_params },
338    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
339    OSSL_DISPATCH_END
340};
341
342static int SSHKDF(const EVP_MD *evp_md,
343                  const unsigned char *key, size_t key_len,
344                  const unsigned char *xcghash, size_t xcghash_len,
345                  const unsigned char *session_id, size_t session_id_len,
346                  char type, unsigned char *okey, size_t okey_len)
347{
348    EVP_MD_CTX *md = NULL;
349    unsigned char digest[EVP_MAX_MD_SIZE];
350    unsigned int dsize = 0;
351    size_t cursize = 0;
352    int ret = 0;
353
354    md = EVP_MD_CTX_new();
355    if (md == NULL)
356        return 0;
357
358    if (!EVP_DigestInit_ex(md, evp_md, NULL))
359        goto out;
360
361    if (!EVP_DigestUpdate(md, key, key_len))
362        goto out;
363
364    if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
365        goto out;
366
367    if (!EVP_DigestUpdate(md, &type, 1))
368        goto out;
369
370    if (!EVP_DigestUpdate(md, session_id, session_id_len))
371        goto out;
372
373    if (!EVP_DigestFinal_ex(md, digest, &dsize))
374        goto out;
375
376    if (okey_len < dsize) {
377        memcpy(okey, digest, okey_len);
378        ret = 1;
379        goto out;
380    }
381
382    memcpy(okey, digest, dsize);
383
384    for (cursize = dsize; cursize < okey_len; cursize += dsize) {
385
386        if (!EVP_DigestInit_ex(md, evp_md, NULL))
387            goto out;
388
389        if (!EVP_DigestUpdate(md, key, key_len))
390            goto out;
391
392        if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
393            goto out;
394
395        if (!EVP_DigestUpdate(md, okey, cursize))
396            goto out;
397
398        if (!EVP_DigestFinal_ex(md, digest, &dsize))
399            goto out;
400
401        if (okey_len < cursize + dsize) {
402            memcpy(okey + cursize, digest, okey_len - cursize);
403            ret = 1;
404            goto out;
405        }
406
407        memcpy(okey + cursize, digest, dsize);
408    }
409
410    ret = 1;
411
412out:
413    EVP_MD_CTX_free(md);
414    OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
415    return ret;
416}
417