1 /*
2 * Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright 2019 Red Hat, Inc.
4 *
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 */
10
11 /*
12 * This implements https://csrc.nist.gov/publications/detail/sp/800-108/final
13 * section 5.1 ("counter mode") and section 5.2 ("feedback mode") in both HMAC
14 * and CMAC. That document does not name the KDFs it defines; the name is
15 * derived from
16 * https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Key-Derivation
17 *
18 * Note that section 5.3 ("double-pipeline mode") is not implemented, though
19 * it would be possible to do so in the future.
20 *
21 * These versions all assume the counter is used. It would be relatively
22 * straightforward to expose a configuration handle should the need arise.
23 *
24 * Variable names attempt to match those of SP800-108.
25 */
26
27 #include <stdarg.h>
28 #include <stdlib.h>
29 #include <string.h>
30
31 #include <openssl/core_names.h>
32 #include <openssl/evp.h>
33 #include <openssl/hmac.h>
34 #include <openssl/kdf.h>
35 #include <openssl/params.h>
36 #include <openssl/proverr.h>
37
38 #include "internal/cryptlib.h"
39 #include "crypto/evp.h"
40 #include "internal/numbers.h"
41 #include "internal/endian.h"
42 #include "prov/implementations.h"
43 #include "prov/provider_ctx.h"
44 #include "prov/provider_util.h"
45 #include "prov/providercommon.h"
46
47 #include "e_os.h"
48
49 #define ossl_min(a, b) ((a) < (b)) ? (a) : (b)
50
51 typedef enum {
52 COUNTER = 0,
53 FEEDBACK
54 } kbkdf_mode;
55
56 /* Our context structure. */
57 typedef struct {
58 void *provctx;
59 kbkdf_mode mode;
60 EVP_MAC_CTX *ctx_init;
61
62 /* Names are lowercased versions of those found in SP800-108. */
63 unsigned char *ki;
64 size_t ki_len;
65 unsigned char *label;
66 size_t label_len;
67 unsigned char *context;
68 size_t context_len;
69 unsigned char *iv;
70 size_t iv_len;
71 int use_l;
72 int use_separator;
73 } KBKDF;
74
75 /* Definitions needed for typechecking. */
76 static OSSL_FUNC_kdf_newctx_fn kbkdf_new;
77 static OSSL_FUNC_kdf_freectx_fn kbkdf_free;
78 static OSSL_FUNC_kdf_reset_fn kbkdf_reset;
79 static OSSL_FUNC_kdf_derive_fn kbkdf_derive;
80 static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params;
81 static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params;
82 static OSSL_FUNC_kdf_gettable_ctx_params_fn kbkdf_gettable_ctx_params;
83 static OSSL_FUNC_kdf_get_ctx_params_fn kbkdf_get_ctx_params;
84
85 /* Not all platforms have htobe32(). */
be32(uint32_t host)86 static uint32_t be32(uint32_t host)
87 {
88 uint32_t big = 0;
89 DECLARE_IS_ENDIAN;
90
91 if (!IS_LITTLE_ENDIAN)
92 return host;
93
94 big |= (host & 0xff000000) >> 24;
95 big |= (host & 0x00ff0000) >> 8;
96 big |= (host & 0x0000ff00) << 8;
97 big |= (host & 0x000000ff) << 24;
98 return big;
99 }
100
init(KBKDF * ctx)101 static void init(KBKDF *ctx)
102 {
103 ctx->use_l = 1;
104 ctx->use_separator = 1;
105 }
106
kbkdf_new(void * provctx)107 static void *kbkdf_new(void *provctx)
108 {
109 KBKDF *ctx;
110
111 if (!ossl_prov_is_running())
112 return NULL;
113
114 ctx = OPENSSL_zalloc(sizeof(*ctx));
115 if (ctx == NULL) {
116 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
117 return NULL;
118 }
119
120 ctx->provctx = provctx;
121 init(ctx);
122 return ctx;
123 }
124
kbkdf_free(void * vctx)125 static void kbkdf_free(void *vctx)
126 {
127 KBKDF *ctx = (KBKDF *)vctx;
128
129 if (ctx != NULL) {
130 kbkdf_reset(ctx);
131 OPENSSL_free(ctx);
132 }
133 }
134
kbkdf_reset(void * vctx)135 static void kbkdf_reset(void *vctx)
136 {
137 KBKDF *ctx = (KBKDF *)vctx;
138 void *provctx = ctx->provctx;
139
140 EVP_MAC_CTX_free(ctx->ctx_init);
141 OPENSSL_clear_free(ctx->context, ctx->context_len);
142 OPENSSL_clear_free(ctx->label, ctx->label_len);
143 OPENSSL_clear_free(ctx->ki, ctx->ki_len);
144 OPENSSL_clear_free(ctx->iv, ctx->iv_len);
145 memset(ctx, 0, sizeof(*ctx));
146 ctx->provctx = provctx;
147 init(ctx);
148 }
149
150 /* SP800-108 section 5.1 or section 5.2 depending on mode. */
derive(EVP_MAC_CTX * ctx_init,kbkdf_mode mode,unsigned char * iv,size_t iv_len,unsigned char * label,size_t label_len,unsigned char * context,size_t context_len,unsigned char * k_i,size_t h,uint32_t l,int has_separator,unsigned char * ko,size_t ko_len)151 static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv,
152 size_t iv_len, unsigned char *label, size_t label_len,
153 unsigned char *context, size_t context_len,
154 unsigned char *k_i, size_t h, uint32_t l, int has_separator,
155 unsigned char *ko, size_t ko_len)
156 {
157 int ret = 0;
158 EVP_MAC_CTX *ctx = NULL;
159 size_t written = 0, to_write, k_i_len = iv_len;
160 const unsigned char zero = 0;
161 uint32_t counter, i;
162 /*
163 * From SP800-108:
164 * The fixed input data is a concatenation of a Label,
165 * a separation indicator 0x00, the Context, and L.
166 * One or more of these fixed input data fields may be omitted.
167 *
168 * has_separator == 0 means that the separator is omitted.
169 * Passing a value of l == 0 means that L is omitted.
170 * The Context and L are omitted automatically if a NULL buffer is passed.
171 */
172 int has_l = (l != 0);
173
174 /* Setup K(0) for feedback mode. */
175 if (iv_len > 0)
176 memcpy(k_i, iv, iv_len);
177
178 for (counter = 1; written < ko_len; counter++) {
179 i = be32(counter);
180
181 ctx = EVP_MAC_CTX_dup(ctx_init);
182 if (ctx == NULL)
183 goto done;
184
185 /* Perform feedback, if appropriate. */
186 if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len))
187 goto done;
188
189 if (!EVP_MAC_update(ctx, (unsigned char *)&i, 4)
190 || !EVP_MAC_update(ctx, label, label_len)
191 || (has_separator && !EVP_MAC_update(ctx, &zero, 1))
192 || !EVP_MAC_update(ctx, context, context_len)
193 || (has_l && !EVP_MAC_update(ctx, (unsigned char *)&l, 4))
194 || !EVP_MAC_final(ctx, k_i, NULL, h))
195 goto done;
196
197 to_write = ko_len - written;
198 memcpy(ko + written, k_i, ossl_min(to_write, h));
199 written += h;
200
201 k_i_len = h;
202 EVP_MAC_CTX_free(ctx);
203 ctx = NULL;
204 }
205
206 ret = 1;
207 done:
208 EVP_MAC_CTX_free(ctx);
209 return ret;
210 }
211
kbkdf_derive(void * vctx,unsigned char * key,size_t keylen,const OSSL_PARAM params[])212 static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen,
213 const OSSL_PARAM params[])
214 {
215 KBKDF *ctx = (KBKDF *)vctx;
216 int ret = 0;
217 unsigned char *k_i = NULL;
218 uint32_t l = 0;
219 size_t h = 0;
220
221 if (!ossl_prov_is_running() || !kbkdf_set_ctx_params(ctx, params))
222 return 0;
223
224 /* label, context, and iv are permitted to be empty. Check everything
225 * else. */
226 if (ctx->ctx_init == NULL) {
227 if (ctx->ki_len == 0 || ctx->ki == NULL) {
228 ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
229 return 0;
230 }
231 /* Could either be missing MAC or missing message digest or missing
232 * cipher - arbitrarily, I pick this one. */
233 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC);
234 return 0;
235 }
236
237 /* Fail if the output length is zero */
238 if (keylen == 0) {
239 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
240 return 0;
241 }
242
243 h = EVP_MAC_CTX_get_mac_size(ctx->ctx_init);
244 if (h == 0)
245 goto done;
246 if (ctx->iv_len != 0 && ctx->iv_len != h) {
247 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH);
248 goto done;
249 }
250
251 if (ctx->use_l != 0)
252 l = be32(keylen * 8);
253
254 k_i = OPENSSL_zalloc(h);
255 if (k_i == NULL)
256 goto done;
257
258 ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label,
259 ctx->label_len, ctx->context, ctx->context_len, k_i, h, l,
260 ctx->use_separator, key, keylen);
261 done:
262 if (ret != 1)
263 OPENSSL_cleanse(key, keylen);
264 OPENSSL_clear_free(k_i, h);
265 return ret;
266 }
267
kbkdf_set_buffer(unsigned char ** out,size_t * out_len,const OSSL_PARAM * p)268 static int kbkdf_set_buffer(unsigned char **out, size_t *out_len,
269 const OSSL_PARAM *p)
270 {
271 if (p->data == NULL || p->data_size == 0)
272 return 1;
273
274 OPENSSL_clear_free(*out, *out_len);
275 *out = NULL;
276 return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
277 }
278
kbkdf_set_ctx_params(void * vctx,const OSSL_PARAM params[])279 static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
280 {
281 KBKDF *ctx = (KBKDF *)vctx;
282 OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
283 const OSSL_PARAM *p;
284
285 if (params == NULL)
286 return 1;
287
288 if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL,
289 NULL, NULL, libctx))
290 return 0;
291 else if (ctx->ctx_init != NULL
292 && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
293 OSSL_MAC_NAME_HMAC)
294 && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
295 OSSL_MAC_NAME_CMAC)) {
296 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC);
297 return 0;
298 }
299
300 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE);
301 if (p != NULL
302 && OPENSSL_strncasecmp("counter", p->data, p->data_size) == 0) {
303 ctx->mode = COUNTER;
304 } else if (p != NULL
305 && OPENSSL_strncasecmp("feedback", p->data, p->data_size) == 0) {
306 ctx->mode = FEEDBACK;
307 } else if (p != NULL) {
308 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
309 return 0;
310 }
311
312 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY);
313 if (p != NULL && !kbkdf_set_buffer(&ctx->ki, &ctx->ki_len, p))
314 return 0;
315
316 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT);
317 if (p != NULL && !kbkdf_set_buffer(&ctx->label, &ctx->label_len, p))
318 return 0;
319
320 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO);
321 if (p != NULL && !kbkdf_set_buffer(&ctx->context, &ctx->context_len, p))
322 return 0;
323
324 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED);
325 if (p != NULL && !kbkdf_set_buffer(&ctx->iv, &ctx->iv_len, p))
326 return 0;
327
328 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_L);
329 if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_l))
330 return 0;
331
332 p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR);
333 if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_separator))
334 return 0;
335
336 /* Set up digest context, if we can. */
337 if (ctx->ctx_init != NULL && ctx->ki_len != 0
338 && !EVP_MAC_init(ctx->ctx_init, ctx->ki, ctx->ki_len, NULL))
339 return 0;
340 return 1;
341 }
342
kbkdf_settable_ctx_params(ossl_unused void * ctx,ossl_unused void * provctx)343 static const OSSL_PARAM *kbkdf_settable_ctx_params(ossl_unused void *ctx,
344 ossl_unused void *provctx)
345 {
346 static const OSSL_PARAM known_settable_ctx_params[] = {
347 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
348 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
349 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
350 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
351 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
352 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
353 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
354 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
355 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
356 OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_L, NULL),
357 OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR, NULL),
358 OSSL_PARAM_END,
359 };
360 return known_settable_ctx_params;
361 }
362
kbkdf_get_ctx_params(void * vctx,OSSL_PARAM params[])363 static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
364 {
365 OSSL_PARAM *p;
366
367 p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE);
368 if (p == NULL)
369 return -2;
370
371 /* KBKDF can produce results as large as you like. */
372 return OSSL_PARAM_set_size_t(p, SIZE_MAX);
373 }
374
kbkdf_gettable_ctx_params(ossl_unused void * ctx,ossl_unused void * provctx)375 static const OSSL_PARAM *kbkdf_gettable_ctx_params(ossl_unused void *ctx,
376 ossl_unused void *provctx)
377 {
378 static const OSSL_PARAM known_gettable_ctx_params[] =
379 { OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), OSSL_PARAM_END };
380 return known_gettable_ctx_params;
381 }
382
383 const OSSL_DISPATCH ossl_kdf_kbkdf_functions[] = {
384 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new },
385 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free },
386 { OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset },
387 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive },
388 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
389 (void(*)(void))kbkdf_settable_ctx_params },
390 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params },
391 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
392 (void(*)(void))kbkdf_gettable_ctx_params },
393 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params },
394 { 0, NULL },
395 };
396