1/*
2 * Copyright 2019-2022 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/*
11 * DH low level APIs are deprecated for public use, but still ok for
12 * internal use.
13 */
14#include "internal/deprecated.h"
15
16#include <string.h>
17#include <openssl/crypto.h>
18#include <openssl/core_dispatch.h>
19#include <openssl/core_names.h>
20#include <openssl/dh.h>
21#include <openssl/err.h>
22#include <openssl/proverr.h>
23#include <openssl/params.h>
24#include "prov/providercommon.h"
25#include "prov/implementations.h"
26#include "prov/provider_ctx.h"
27#include "prov/securitycheck.h"
28#include "crypto/dh.h"
29
30static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
31static OSSL_FUNC_keyexch_init_fn dh_init;
32static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
33static OSSL_FUNC_keyexch_derive_fn dh_derive;
34static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
35static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
36static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
37static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
38static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
39static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;
40
41/*
42 * This type is only really used to handle some legacy related functionality.
43 * If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
44 * here and then create and run a KDF after the key is derived.
45 * Note that X942 has 2 variants of key derivation:
46 *   (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
47 *   the counter embedded in it.
48 *   (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
49 *       done by creating a "X963KDF".
50 */
51enum kdf_type {
52    PROV_DH_KDF_NONE = 0,
53    PROV_DH_KDF_X9_42_ASN1
54};
55
56/*
57 * What's passed as an actual key is defined by the KEYMGMT interface.
58 * We happen to know that our KEYMGMT simply passes DH structures, so
59 * we use that here too.
60 */
61
62typedef struct {
63    OSSL_LIB_CTX *libctx;
64    DH *dh;
65    DH *dhpeer;
66    unsigned int pad : 1;
67
68    /* DH KDF */
69    /* KDF (if any) to use for DH */
70    enum kdf_type kdf_type;
71    /* Message digest to use for key derivation */
72    EVP_MD *kdf_md;
73    /* User key material */
74    unsigned char *kdf_ukm;
75    size_t kdf_ukmlen;
76    /* KDF output length */
77    size_t kdf_outlen;
78    char *kdf_cekalg;
79} PROV_DH_CTX;
80
81static void *dh_newctx(void *provctx)
82{
83    PROV_DH_CTX *pdhctx;
84
85    if (!ossl_prov_is_running())
86        return NULL;
87
88    pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
89    if (pdhctx == NULL)
90        return NULL;
91    pdhctx->libctx = PROV_LIBCTX_OF(provctx);
92    pdhctx->kdf_type = PROV_DH_KDF_NONE;
93    return pdhctx;
94}
95
96static int dh_init(void *vpdhctx, void *vdh, const OSSL_PARAM params[])
97{
98    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
99
100    if (!ossl_prov_is_running()
101            || pdhctx == NULL
102            || vdh == NULL
103            || !DH_up_ref(vdh))
104        return 0;
105    DH_free(pdhctx->dh);
106    pdhctx->dh = vdh;
107    pdhctx->kdf_type = PROV_DH_KDF_NONE;
108    return dh_set_ctx_params(pdhctx, params)
109           && ossl_dh_check_key(pdhctx->libctx, vdh);
110}
111
112/* The 2 parties must share the same domain parameters */
113static int dh_match_params(DH *priv, DH *peer)
114{
115    int ret;
116    FFC_PARAMS *dhparams_priv = ossl_dh_get0_params(priv);
117    FFC_PARAMS *dhparams_peer = ossl_dh_get0_params(peer);
118
119    ret = dhparams_priv != NULL
120          && dhparams_peer != NULL
121          && ossl_ffc_params_cmp(dhparams_priv, dhparams_peer, 1);
122    if (!ret)
123        ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
124    return ret;
125}
126
127static int dh_set_peer(void *vpdhctx, void *vdh)
128{
129    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
130
131    if (!ossl_prov_is_running()
132            || pdhctx == NULL
133            || vdh == NULL
134            || !dh_match_params(vdh, pdhctx->dh)
135            || !DH_up_ref(vdh))
136        return 0;
137    DH_free(pdhctx->dhpeer);
138    pdhctx->dhpeer = vdh;
139    return 1;
140}
141
142static int dh_plain_derive(void *vpdhctx,
143                           unsigned char *secret, size_t *secretlen,
144                           size_t outlen, unsigned int pad)
145{
146    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
147    int ret;
148    size_t dhsize;
149    const BIGNUM *pub_key = NULL;
150
151    if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL) {
152        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
153        return 0;
154    }
155
156    dhsize = (size_t)DH_size(pdhctx->dh);
157    if (secret == NULL) {
158        *secretlen = dhsize;
159        return 1;
160    }
161    if (outlen < dhsize) {
162        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
163        return 0;
164    }
165
166    DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
167    if (pad)
168        ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
169    else
170        ret = DH_compute_key(secret, pub_key, pdhctx->dh);
171    if (ret <= 0)
172        return 0;
173
174    *secretlen = ret;
175    return 1;
176}
177
178static int dh_X9_42_kdf_derive(void *vpdhctx, unsigned char *secret,
179                               size_t *secretlen, size_t outlen)
180{
181    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
182    unsigned char *stmp = NULL;
183    size_t stmplen;
184    int ret = 0;
185
186    if (secret == NULL) {
187        *secretlen = pdhctx->kdf_outlen;
188        return 1;
189    }
190
191    if (pdhctx->kdf_outlen > outlen) {
192        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
193        return 0;
194    }
195    if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0, 1))
196        return 0;
197    if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL) {
198        ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
199        return 0;
200    }
201    if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
202        goto err;
203
204    /* Do KDF stuff */
205    if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
206        if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
207                                    stmp, stmplen,
208                                    pdhctx->kdf_cekalg,
209                                    pdhctx->kdf_ukm,
210                                    pdhctx->kdf_ukmlen,
211                                    pdhctx->kdf_md,
212                                    pdhctx->libctx, NULL))
213            goto err;
214    }
215    *secretlen = pdhctx->kdf_outlen;
216    ret = 1;
217err:
218    OPENSSL_secure_clear_free(stmp, stmplen);
219    return ret;
220}
221
222static int dh_derive(void *vpdhctx, unsigned char *secret,
223                     size_t *psecretlen, size_t outlen)
224{
225    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
226
227    if (!ossl_prov_is_running())
228        return 0;
229
230    switch (pdhctx->kdf_type) {
231        case PROV_DH_KDF_NONE:
232            return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
233                                   pdhctx->pad);
234        case PROV_DH_KDF_X9_42_ASN1:
235            return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
236        default:
237            break;
238    }
239    return 0;
240}
241
242static void dh_freectx(void *vpdhctx)
243{
244    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
245
246    OPENSSL_free(pdhctx->kdf_cekalg);
247    DH_free(pdhctx->dh);
248    DH_free(pdhctx->dhpeer);
249    EVP_MD_free(pdhctx->kdf_md);
250    OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
251
252    OPENSSL_free(pdhctx);
253}
254
255static void *dh_dupctx(void *vpdhctx)
256{
257    PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
258    PROV_DH_CTX *dstctx;
259
260    if (!ossl_prov_is_running())
261        return NULL;
262
263    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
264    if (dstctx == NULL)
265        return NULL;
266
267    *dstctx = *srcctx;
268    dstctx->dh = NULL;
269    dstctx->dhpeer = NULL;
270    dstctx->kdf_md = NULL;
271    dstctx->kdf_ukm = NULL;
272    dstctx->kdf_cekalg = NULL;
273
274    if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
275        goto err;
276    else
277        dstctx->dh = srcctx->dh;
278
279    if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
280        goto err;
281    else
282        dstctx->dhpeer = srcctx->dhpeer;
283
284    if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
285        goto err;
286    else
287        dstctx->kdf_md = srcctx->kdf_md;
288
289    /* Duplicate UKM data if present */
290    if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
291        dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
292                                         srcctx->kdf_ukmlen);
293        if (dstctx->kdf_ukm == NULL)
294            goto err;
295    }
296
297    if (srcctx->kdf_cekalg != NULL) {
298        dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
299        if (dstctx->kdf_cekalg == NULL)
300            goto err;
301    }
302
303    return dstctx;
304err:
305    dh_freectx(dstctx);
306    return NULL;
307}
308
309static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
310{
311    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
312    const OSSL_PARAM *p;
313    unsigned int pad;
314    char name[80] = { '\0' }; /* should be big enough */
315    char *str = NULL;
316
317    if (pdhctx == NULL)
318        return 0;
319    if (params == NULL)
320        return 1;
321
322    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
323    if (p != NULL) {
324        str = name;
325        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
326            return 0;
327
328        if (name[0] == '\0')
329            pdhctx->kdf_type = PROV_DH_KDF_NONE;
330        else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
331            pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
332        else
333            return 0;
334    }
335    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
336    if (p != NULL) {
337        char mdprops[80] = { '\0' }; /* should be big enough */
338
339        str = name;
340        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
341            return 0;
342
343        str = mdprops;
344        p = OSSL_PARAM_locate_const(params,
345                                    OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
346
347        if (p != NULL) {
348            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
349                return 0;
350        }
351
352        EVP_MD_free(pdhctx->kdf_md);
353        pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
354        if (!ossl_digest_is_allowed(pdhctx->libctx, pdhctx->kdf_md)) {
355            EVP_MD_free(pdhctx->kdf_md);
356            pdhctx->kdf_md = NULL;
357        }
358        if (pdhctx->kdf_md == NULL)
359            return 0;
360    }
361
362    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
363    if (p != NULL) {
364        size_t outlen;
365
366        if (!OSSL_PARAM_get_size_t(p, &outlen))
367            return 0;
368        pdhctx->kdf_outlen = outlen;
369    }
370
371    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
372    if (p != NULL) {
373        void *tmp_ukm = NULL;
374        size_t tmp_ukmlen;
375
376        OPENSSL_free(pdhctx->kdf_ukm);
377        pdhctx->kdf_ukm = NULL;
378        pdhctx->kdf_ukmlen = 0;
379        /* ukm is an optional field so it can be NULL */
380        if (p->data != NULL && p->data_size != 0) {
381            if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
382                return 0;
383            pdhctx->kdf_ukm = tmp_ukm;
384            pdhctx->kdf_ukmlen = tmp_ukmlen;
385        }
386    }
387
388    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
389    if (p != NULL) {
390        if (!OSSL_PARAM_get_uint(p, &pad))
391            return 0;
392        pdhctx->pad = pad ? 1 : 0;
393    }
394
395    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
396    if (p != NULL) {
397        str = name;
398
399        OPENSSL_free(pdhctx->kdf_cekalg);
400        pdhctx->kdf_cekalg = NULL;
401        if (p->data != NULL && p->data_size != 0) {
402            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
403                return 0;
404            pdhctx->kdf_cekalg = OPENSSL_strdup(name);
405            if (pdhctx->kdf_cekalg == NULL)
406                return 0;
407        }
408    }
409    return 1;
410}
411
412static const OSSL_PARAM known_settable_ctx_params[] = {
413    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
414    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
415    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
416    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
417    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
418    OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
419    OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
420    OSSL_PARAM_END
421};
422
423static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *vpdhctx,
424                                                ossl_unused void *provctx)
425{
426    return known_settable_ctx_params;
427}
428
429static const OSSL_PARAM known_gettable_ctx_params[] = {
430    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
431    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
432    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
433    OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
434                    NULL, 0),
435    OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
436    OSSL_PARAM_END
437};
438
439static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *vpdhctx,
440                                                ossl_unused void *provctx)
441{
442    return known_gettable_ctx_params;
443}
444
445static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
446{
447    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
448    OSSL_PARAM *p;
449
450    if (pdhctx == NULL)
451        return 0;
452
453    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
454    if (p != NULL) {
455        const char *kdf_type = NULL;
456
457        switch (pdhctx->kdf_type) {
458            case PROV_DH_KDF_NONE:
459                kdf_type = "";
460                break;
461            case PROV_DH_KDF_X9_42_ASN1:
462                kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
463                break;
464            default:
465                return 0;
466        }
467
468        if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
469            return 0;
470    }
471
472    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
473    if (p != NULL
474            && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
475                                           ? ""
476                                           : EVP_MD_get0_name(pdhctx->kdf_md))){
477        return 0;
478    }
479
480    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
481    if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
482        return 0;
483
484    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
485    if (p != NULL
486        && !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
487        return 0;
488
489    p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
490    if (p != NULL
491            && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
492                                           ? "" :  pdhctx->kdf_cekalg))
493        return 0;
494
495    return 1;
496}
497
498const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
499    { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
500    { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
501    { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
502    { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
503    { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
504    { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
505    { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
506    { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
507      (void (*)(void))dh_settable_ctx_params },
508    { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
509    { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
510      (void (*)(void))dh_gettable_ctx_params },
511    { 0, NULL }
512};
513