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 
kdf_sshkdf_new(void * provctx)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 
kdf_sshkdf_free(void * vctx)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 
kdf_sshkdf_reset(void * vctx)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 
kdf_sshkdf_dup(void * vctx)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 
sshkdf_set_membuf(unsigned char ** dst,size_t * dst_len,const OSSL_PARAM * p)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
fips_digest_check_passed(KDF_SSHKDF * ctx,const EVP_MD * md)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 
fips_key_check_passed(KDF_SSHKDF * ctx)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 
kdf_sshkdf_derive(void * vctx,unsigned char * key,size_t keylen,const OSSL_PARAM params[])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 
kdf_sshkdf_set_ctx_params(void * vctx,const OSSL_PARAM params[])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 (params == NULL)
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 
kdf_sshkdf_settable_ctx_params(ossl_unused void * ctx,ossl_unused void * p_ctx)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 
kdf_sshkdf_get_ctx_params(void * vctx,OSSL_PARAM params[])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 
kdf_sshkdf_gettable_ctx_params(ossl_unused void * ctx,ossl_unused void * p_ctx)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 
SSHKDF(const EVP_MD * evp_md,const unsigned char * key,size_t key_len,const unsigned char * xcghash,size_t xcghash_len,const unsigned char * session_id,size_t session_id_len,char type,unsigned char * okey,size_t okey_len)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