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Linux/crypto/drbg.c

  1 /*
  2  * DRBG: Deterministic Random Bits Generator
  3  *       Based on NIST Recommended DRBG from NIST SP800-90A with the following
  4  *       properties:
  5  *              * CTR DRBG with DF with AES-128, AES-192, AES-256 cores
  6  *              * Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
  7  *              * HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
  8  *              * with and without prediction resistance
  9  *
 10  * Copyright Stephan Mueller <smueller@chronox.de>, 2014
 11  *
 12  * Redistribution and use in source and binary forms, with or without
 13  * modification, are permitted provided that the following conditions
 14  * are met:
 15  * 1. Redistributions of source code must retain the above copyright
 16  *    notice, and the entire permission notice in its entirety,
 17  *    including the disclaimer of warranties.
 18  * 2. Redistributions in binary form must reproduce the above copyright
 19  *    notice, this list of conditions and the following disclaimer in the
 20  *    documentation and/or other materials provided with the distribution.
 21  * 3. The name of the author may not be used to endorse or promote
 22  *    products derived from this software without specific prior
 23  *    written permission.
 24  *
 25  * ALTERNATIVELY, this product may be distributed under the terms of
 26  * the GNU General Public License, in which case the provisions of the GPL are
 27  * required INSTEAD OF the above restrictions.  (This clause is
 28  * necessary due to a potential bad interaction between the GPL and
 29  * the restrictions contained in a BSD-style copyright.)
 30  *
 31  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 32  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 34  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 35  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 36  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 37  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 38  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 39  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 40  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 41  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 42  * DAMAGE.
 43  *
 44  * DRBG Usage
 45  * ==========
 46  * The SP 800-90A DRBG allows the user to specify a personalization string
 47  * for initialization as well as an additional information string for each
 48  * random number request. The following code fragments show how a caller
 49  * uses the kernel crypto API to use the full functionality of the DRBG.
 50  *
 51  * Usage without any additional data
 52  * ---------------------------------
 53  * struct crypto_rng *drng;
 54  * int err;
 55  * char data[DATALEN];
 56  *
 57  * drng = crypto_alloc_rng(drng_name, 0, 0);
 58  * err = crypto_rng_get_bytes(drng, &data, DATALEN);
 59  * crypto_free_rng(drng);
 60  *
 61  *
 62  * Usage with personalization string during initialization
 63  * -------------------------------------------------------
 64  * struct crypto_rng *drng;
 65  * int err;
 66  * char data[DATALEN];
 67  * struct drbg_string pers;
 68  * char personalization[11] = "some-string";
 69  *
 70  * drbg_string_fill(&pers, personalization, strlen(personalization));
 71  * drng = crypto_alloc_rng(drng_name, 0, 0);
 72  * // The reset completely re-initializes the DRBG with the provided
 73  * // personalization string
 74  * err = crypto_rng_reset(drng, &personalization, strlen(personalization));
 75  * err = crypto_rng_get_bytes(drng, &data, DATALEN);
 76  * crypto_free_rng(drng);
 77  *
 78  *
 79  * Usage with additional information string during random number request
 80  * ---------------------------------------------------------------------
 81  * struct crypto_rng *drng;
 82  * int err;
 83  * char data[DATALEN];
 84  * char addtl_string[11] = "some-string";
 85  * string drbg_string addtl;
 86  *
 87  * drbg_string_fill(&addtl, addtl_string, strlen(addtl_string));
 88  * drng = crypto_alloc_rng(drng_name, 0, 0);
 89  * // The following call is a wrapper to crypto_rng_get_bytes() and returns
 90  * // the same error codes.
 91  * err = crypto_drbg_get_bytes_addtl(drng, &data, DATALEN, &addtl);
 92  * crypto_free_rng(drng);
 93  *
 94  *
 95  * Usage with personalization and additional information strings
 96  * -------------------------------------------------------------
 97  * Just mix both scenarios above.
 98  */
 99 
100 #include <crypto/drbg.h>
101 #include <linux/kernel.h>
102 
103 /***************************************************************
104  * Backend cipher definitions available to DRBG
105  ***************************************************************/
106 
107 /*
108  * The order of the DRBG definitions here matter: every DRBG is registered
109  * as stdrng. Each DRBG receives an increasing cra_priority values the later
110  * they are defined in this array (see drbg_fill_array).
111  *
112  * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
113  * the SHA256 / AES 256 over other ciphers. Thus, the favored
114  * DRBGs are the latest entries in this array.
115  */
116 static const struct drbg_core drbg_cores[] = {
117 #ifdef CONFIG_CRYPTO_DRBG_CTR
118         {
119                 .flags = DRBG_CTR | DRBG_STRENGTH128,
120                 .statelen = 32, /* 256 bits as defined in 10.2.1 */
121                 .blocklen_bytes = 16,
122                 .cra_name = "ctr_aes128",
123                 .backend_cra_name = "aes",
124         }, {
125                 .flags = DRBG_CTR | DRBG_STRENGTH192,
126                 .statelen = 40, /* 320 bits as defined in 10.2.1 */
127                 .blocklen_bytes = 16,
128                 .cra_name = "ctr_aes192",
129                 .backend_cra_name = "aes",
130         }, {
131                 .flags = DRBG_CTR | DRBG_STRENGTH256,
132                 .statelen = 48, /* 384 bits as defined in 10.2.1 */
133                 .blocklen_bytes = 16,
134                 .cra_name = "ctr_aes256",
135                 .backend_cra_name = "aes",
136         },
137 #endif /* CONFIG_CRYPTO_DRBG_CTR */
138 #ifdef CONFIG_CRYPTO_DRBG_HASH
139         {
140                 .flags = DRBG_HASH | DRBG_STRENGTH128,
141                 .statelen = 55, /* 440 bits */
142                 .blocklen_bytes = 20,
143                 .cra_name = "sha1",
144                 .backend_cra_name = "sha1",
145         }, {
146                 .flags = DRBG_HASH | DRBG_STRENGTH256,
147                 .statelen = 111, /* 888 bits */
148                 .blocklen_bytes = 48,
149                 .cra_name = "sha384",
150                 .backend_cra_name = "sha384",
151         }, {
152                 .flags = DRBG_HASH | DRBG_STRENGTH256,
153                 .statelen = 111, /* 888 bits */
154                 .blocklen_bytes = 64,
155                 .cra_name = "sha512",
156                 .backend_cra_name = "sha512",
157         }, {
158                 .flags = DRBG_HASH | DRBG_STRENGTH256,
159                 .statelen = 55, /* 440 bits */
160                 .blocklen_bytes = 32,
161                 .cra_name = "sha256",
162                 .backend_cra_name = "sha256",
163         },
164 #endif /* CONFIG_CRYPTO_DRBG_HASH */
165 #ifdef CONFIG_CRYPTO_DRBG_HMAC
166         {
167                 .flags = DRBG_HMAC | DRBG_STRENGTH128,
168                 .statelen = 20, /* block length of cipher */
169                 .blocklen_bytes = 20,
170                 .cra_name = "hmac_sha1",
171                 .backend_cra_name = "hmac(sha1)",
172         }, {
173                 .flags = DRBG_HMAC | DRBG_STRENGTH256,
174                 .statelen = 48, /* block length of cipher */
175                 .blocklen_bytes = 48,
176                 .cra_name = "hmac_sha384",
177                 .backend_cra_name = "hmac(sha384)",
178         }, {
179                 .flags = DRBG_HMAC | DRBG_STRENGTH256,
180                 .statelen = 64, /* block length of cipher */
181                 .blocklen_bytes = 64,
182                 .cra_name = "hmac_sha512",
183                 .backend_cra_name = "hmac(sha512)",
184         }, {
185                 .flags = DRBG_HMAC | DRBG_STRENGTH256,
186                 .statelen = 32, /* block length of cipher */
187                 .blocklen_bytes = 32,
188                 .cra_name = "hmac_sha256",
189                 .backend_cra_name = "hmac(sha256)",
190         },
191 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
192 };
193 
194 static int drbg_uninstantiate(struct drbg_state *drbg);
195 
196 /******************************************************************
197  * Generic helper functions
198  ******************************************************************/
199 
200 /*
201  * Return strength of DRBG according to SP800-90A section 8.4
202  *
203  * @flags DRBG flags reference
204  *
205  * Return: normalized strength in *bytes* value or 32 as default
206  *         to counter programming errors
207  */
208 static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
209 {
210         switch (flags & DRBG_STRENGTH_MASK) {
211         case DRBG_STRENGTH128:
212                 return 16;
213         case DRBG_STRENGTH192:
214                 return 24;
215         case DRBG_STRENGTH256:
216                 return 32;
217         default:
218                 return 32;
219         }
220 }
221 
222 /*
223  * Convert an integer into a byte representation of this integer.
224  * The byte representation is big-endian
225  *
226  * @val value to be converted
227  * @buf buffer holding the converted integer -- caller must ensure that
228  *      buffer size is at least 32 bit
229  */
230 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
231 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
232 {
233         struct s {
234                 __be32 conv;
235         };
236         struct s *conversion = (struct s *) buf;
237 
238         conversion->conv = cpu_to_be32(val);
239 }
240 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
241 
242 /******************************************************************
243  * CTR DRBG callback functions
244  ******************************************************************/
245 
246 #ifdef CONFIG_CRYPTO_DRBG_CTR
247 #define CRYPTO_DRBG_CTR_STRING "CTR "
248 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
249 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
250 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
251 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
252 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
253 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
254 
255 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
256                                  const unsigned char *key);
257 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
258                           const struct drbg_string *in);
259 static int drbg_init_sym_kernel(struct drbg_state *drbg);
260 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
261 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
262                               u8 *inbuf, u32 inbuflen,
263                               u8 *outbuf, u32 outlen);
264 #define DRBG_CTR_NULL_LEN 128
265 #define DRBG_OUTSCRATCHLEN DRBG_CTR_NULL_LEN
266 
267 /* BCC function for CTR DRBG as defined in 10.4.3 */
268 static int drbg_ctr_bcc(struct drbg_state *drbg,
269                         unsigned char *out, const unsigned char *key,
270                         struct list_head *in)
271 {
272         int ret = 0;
273         struct drbg_string *curr = NULL;
274         struct drbg_string data;
275         short cnt = 0;
276 
277         drbg_string_fill(&data, out, drbg_blocklen(drbg));
278 
279         /* 10.4.3 step 2 / 4 */
280         drbg_kcapi_symsetkey(drbg, key);
281         list_for_each_entry(curr, in, list) {
282                 const unsigned char *pos = curr->buf;
283                 size_t len = curr->len;
284                 /* 10.4.3 step 4.1 */
285                 while (len) {
286                         /* 10.4.3 step 4.2 */
287                         if (drbg_blocklen(drbg) == cnt) {
288                                 cnt = 0;
289                                 ret = drbg_kcapi_sym(drbg, out, &data);
290                                 if (ret)
291                                         return ret;
292                         }
293                         out[cnt] ^= *pos;
294                         pos++;
295                         cnt++;
296                         len--;
297                 }
298         }
299         /* 10.4.3 step 4.2 for last block */
300         if (cnt)
301                 ret = drbg_kcapi_sym(drbg, out, &data);
302 
303         return ret;
304 }
305 
306 /*
307  * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
308  * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
309  * the scratchpad is used as follows:
310  * drbg_ctr_update:
311  *      temp
312  *              start: drbg->scratchpad
313  *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
314  *                      note: the cipher writing into this variable works
315  *                      blocklen-wise. Now, when the statelen is not a multiple
316  *                      of blocklen, the generateion loop below "spills over"
317  *                      by at most blocklen. Thus, we need to give sufficient
318  *                      memory.
319  *      df_data
320  *              start: drbg->scratchpad +
321  *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
322  *              length: drbg_statelen(drbg)
323  *
324  * drbg_ctr_df:
325  *      pad
326  *              start: df_data + drbg_statelen(drbg)
327  *              length: drbg_blocklen(drbg)
328  *      iv
329  *              start: pad + drbg_blocklen(drbg)
330  *              length: drbg_blocklen(drbg)
331  *      temp
332  *              start: iv + drbg_blocklen(drbg)
333  *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
334  *                      note: temp is the buffer that the BCC function operates
335  *                      on. BCC operates blockwise. drbg_statelen(drbg)
336  *                      is sufficient when the DRBG state length is a multiple
337  *                      of the block size. For AES192 (and maybe other ciphers)
338  *                      this is not correct and the length for temp is
339  *                      insufficient (yes, that also means for such ciphers,
340  *                      the final output of all BCC rounds are truncated).
341  *                      Therefore, add drbg_blocklen(drbg) to cover all
342  *                      possibilities.
343  */
344 
345 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
346 static int drbg_ctr_df(struct drbg_state *drbg,
347                        unsigned char *df_data, size_t bytes_to_return,
348                        struct list_head *seedlist)
349 {
350         int ret = -EFAULT;
351         unsigned char L_N[8];
352         /* S3 is input */
353         struct drbg_string S1, S2, S4, cipherin;
354         LIST_HEAD(bcc_list);
355         unsigned char *pad = df_data + drbg_statelen(drbg);
356         unsigned char *iv = pad + drbg_blocklen(drbg);
357         unsigned char *temp = iv + drbg_blocklen(drbg);
358         size_t padlen = 0;
359         unsigned int templen = 0;
360         /* 10.4.2 step 7 */
361         unsigned int i = 0;
362         /* 10.4.2 step 8 */
363         const unsigned char *K = (unsigned char *)
364                            "\x00\x01\x02\x03\x04\x05\x06\x07"
365                            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
366                            "\x10\x11\x12\x13\x14\x15\x16\x17"
367                            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
368         unsigned char *X;
369         size_t generated_len = 0;
370         size_t inputlen = 0;
371         struct drbg_string *seed = NULL;
372 
373         memset(pad, 0, drbg_blocklen(drbg));
374         memset(iv, 0, drbg_blocklen(drbg));
375 
376         /* 10.4.2 step 1 is implicit as we work byte-wise */
377 
378         /* 10.4.2 step 2 */
379         if ((512/8) < bytes_to_return)
380                 return -EINVAL;
381 
382         /* 10.4.2 step 2 -- calculate the entire length of all input data */
383         list_for_each_entry(seed, seedlist, list)
384                 inputlen += seed->len;
385         drbg_cpu_to_be32(inputlen, &L_N[0]);
386 
387         /* 10.4.2 step 3 */
388         drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
389 
390         /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
391         padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
392         /* wrap the padlen appropriately */
393         if (padlen)
394                 padlen = drbg_blocklen(drbg) - padlen;
395         /*
396          * pad / padlen contains the 0x80 byte and the following zero bytes.
397          * As the calculated padlen value only covers the number of zero
398          * bytes, this value has to be incremented by one for the 0x80 byte.
399          */
400         padlen++;
401         pad[0] = 0x80;
402 
403         /* 10.4.2 step 4 -- first fill the linked list and then order it */
404         drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
405         list_add_tail(&S1.list, &bcc_list);
406         drbg_string_fill(&S2, L_N, sizeof(L_N));
407         list_add_tail(&S2.list, &bcc_list);
408         list_splice_tail(seedlist, &bcc_list);
409         drbg_string_fill(&S4, pad, padlen);
410         list_add_tail(&S4.list, &bcc_list);
411 
412         /* 10.4.2 step 9 */
413         while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
414                 /*
415                  * 10.4.2 step 9.1 - the padding is implicit as the buffer
416                  * holds zeros after allocation -- even the increment of i
417                  * is irrelevant as the increment remains within length of i
418                  */
419                 drbg_cpu_to_be32(i, iv);
420                 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
421                 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
422                 if (ret)
423                         goto out;
424                 /* 10.4.2 step 9.3 */
425                 i++;
426                 templen += drbg_blocklen(drbg);
427         }
428 
429         /* 10.4.2 step 11 */
430         X = temp + (drbg_keylen(drbg));
431         drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
432 
433         /* 10.4.2 step 12: overwriting of outval is implemented in next step */
434 
435         /* 10.4.2 step 13 */
436         drbg_kcapi_symsetkey(drbg, temp);
437         while (generated_len < bytes_to_return) {
438                 short blocklen = 0;
439                 /*
440                  * 10.4.2 step 13.1: the truncation of the key length is
441                  * implicit as the key is only drbg_blocklen in size based on
442                  * the implementation of the cipher function callback
443                  */
444                 ret = drbg_kcapi_sym(drbg, X, &cipherin);
445                 if (ret)
446                         goto out;
447                 blocklen = (drbg_blocklen(drbg) <
448                                 (bytes_to_return - generated_len)) ?
449                             drbg_blocklen(drbg) :
450                                 (bytes_to_return - generated_len);
451                 /* 10.4.2 step 13.2 and 14 */
452                 memcpy(df_data + generated_len, X, blocklen);
453                 generated_len += blocklen;
454         }
455 
456         ret = 0;
457 
458 out:
459         memset(iv, 0, drbg_blocklen(drbg));
460         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
461         memset(pad, 0, drbg_blocklen(drbg));
462         return ret;
463 }
464 
465 /*
466  * update function of CTR DRBG as defined in 10.2.1.2
467  *
468  * The reseed variable has an enhanced meaning compared to the update
469  * functions of the other DRBGs as follows:
470  * 0 => initial seed from initialization
471  * 1 => reseed via drbg_seed
472  * 2 => first invocation from drbg_ctr_update when addtl is present. In
473  *      this case, the df_data scratchpad is not deleted so that it is
474  *      available for another calls to prevent calling the DF function
475  *      again.
476  * 3 => second invocation from drbg_ctr_update. When the update function
477  *      was called with addtl, the df_data memory already contains the
478  *      DFed addtl information and we do not need to call DF again.
479  */
480 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
481                            int reseed)
482 {
483         int ret = -EFAULT;
484         /* 10.2.1.2 step 1 */
485         unsigned char *temp = drbg->scratchpad;
486         unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
487                                  drbg_blocklen(drbg);
488 
489         if (3 > reseed)
490                 memset(df_data, 0, drbg_statelen(drbg));
491 
492         if (!reseed) {
493                 /*
494                  * The DRBG uses the CTR mode of the underlying AES cipher. The
495                  * CTR mode increments the counter value after the AES operation
496                  * but SP800-90A requires that the counter is incremented before
497                  * the AES operation. Hence, we increment it at the time we set
498                  * it by one.
499                  */
500                 crypto_inc(drbg->V, drbg_blocklen(drbg));
501 
502                 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
503                                              drbg_keylen(drbg));
504                 if (ret)
505                         goto out;
506         }
507 
508         /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
509         if (seed) {
510                 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
511                 if (ret)
512                         goto out;
513         }
514 
515         ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
516                                  temp, drbg_statelen(drbg));
517         if (ret)
518                 return ret;
519 
520         /* 10.2.1.2 step 5 */
521         ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
522                                      drbg_keylen(drbg));
523         if (ret)
524                 goto out;
525         /* 10.2.1.2 step 6 */
526         memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
527         /* See above: increment counter by one to compensate timing of CTR op */
528         crypto_inc(drbg->V, drbg_blocklen(drbg));
529         ret = 0;
530 
531 out:
532         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
533         if (2 != reseed)
534                 memset(df_data, 0, drbg_statelen(drbg));
535         return ret;
536 }
537 
538 /*
539  * scratchpad use: drbg_ctr_update is called independently from
540  * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
541  */
542 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
543 static int drbg_ctr_generate(struct drbg_state *drbg,
544                              unsigned char *buf, unsigned int buflen,
545                              struct list_head *addtl)
546 {
547         int ret;
548         int len = min_t(int, buflen, INT_MAX);
549 
550         /* 10.2.1.5.2 step 2 */
551         if (addtl && !list_empty(addtl)) {
552                 ret = drbg_ctr_update(drbg, addtl, 2);
553                 if (ret)
554                         return 0;
555         }
556 
557         /* 10.2.1.5.2 step 4.1 */
558         ret = drbg_kcapi_sym_ctr(drbg, drbg->ctr_null_value, DRBG_CTR_NULL_LEN,
559                                  buf, len);
560         if (ret)
561                 return ret;
562 
563         /* 10.2.1.5.2 step 6 */
564         ret = drbg_ctr_update(drbg, NULL, 3);
565         if (ret)
566                 len = ret;
567 
568         return len;
569 }
570 
571 static const struct drbg_state_ops drbg_ctr_ops = {
572         .update         = drbg_ctr_update,
573         .generate       = drbg_ctr_generate,
574         .crypto_init    = drbg_init_sym_kernel,
575         .crypto_fini    = drbg_fini_sym_kernel,
576 };
577 #endif /* CONFIG_CRYPTO_DRBG_CTR */
578 
579 /******************************************************************
580  * HMAC DRBG callback functions
581  ******************************************************************/
582 
583 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
584 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
585                            const struct list_head *in);
586 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
587                                   const unsigned char *key);
588 static int drbg_init_hash_kernel(struct drbg_state *drbg);
589 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
590 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
591 
592 #ifdef CONFIG_CRYPTO_DRBG_HMAC
593 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
594 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
595 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
596 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
597 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
598 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
599 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
600 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
601 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
602 
603 /* update function of HMAC DRBG as defined in 10.1.2.2 */
604 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
605                             int reseed)
606 {
607         int ret = -EFAULT;
608         int i = 0;
609         struct drbg_string seed1, seed2, vdata;
610         LIST_HEAD(seedlist);
611         LIST_HEAD(vdatalist);
612 
613         if (!reseed) {
614                 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
615                 memset(drbg->V, 1, drbg_statelen(drbg));
616                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
617         }
618 
619         drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
620         list_add_tail(&seed1.list, &seedlist);
621         /* buffer of seed2 will be filled in for loop below with one byte */
622         drbg_string_fill(&seed2, NULL, 1);
623         list_add_tail(&seed2.list, &seedlist);
624         /* input data of seed is allowed to be NULL at this point */
625         if (seed)
626                 list_splice_tail(seed, &seedlist);
627 
628         drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
629         list_add_tail(&vdata.list, &vdatalist);
630         for (i = 2; 0 < i; i--) {
631                 /* first round uses 0x0, second 0x1 */
632                 unsigned char prefix = DRBG_PREFIX0;
633                 if (1 == i)
634                         prefix = DRBG_PREFIX1;
635                 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
636                 seed2.buf = &prefix;
637                 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
638                 if (ret)
639                         return ret;
640                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
641 
642                 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
643                 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
644                 if (ret)
645                         return ret;
646 
647                 /* 10.1.2.2 step 3 */
648                 if (!seed)
649                         return ret;
650         }
651 
652         return 0;
653 }
654 
655 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
656 static int drbg_hmac_generate(struct drbg_state *drbg,
657                               unsigned char *buf,
658                               unsigned int buflen,
659                               struct list_head *addtl)
660 {
661         int len = 0;
662         int ret = 0;
663         struct drbg_string data;
664         LIST_HEAD(datalist);
665 
666         /* 10.1.2.5 step 2 */
667         if (addtl && !list_empty(addtl)) {
668                 ret = drbg_hmac_update(drbg, addtl, 1);
669                 if (ret)
670                         return ret;
671         }
672 
673         drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
674         list_add_tail(&data.list, &datalist);
675         while (len < buflen) {
676                 unsigned int outlen = 0;
677                 /* 10.1.2.5 step 4.1 */
678                 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
679                 if (ret)
680                         return ret;
681                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
682                           drbg_blocklen(drbg) : (buflen - len);
683 
684                 /* 10.1.2.5 step 4.2 */
685                 memcpy(buf + len, drbg->V, outlen);
686                 len += outlen;
687         }
688 
689         /* 10.1.2.5 step 6 */
690         if (addtl && !list_empty(addtl))
691                 ret = drbg_hmac_update(drbg, addtl, 1);
692         else
693                 ret = drbg_hmac_update(drbg, NULL, 1);
694         if (ret)
695                 return ret;
696 
697         return len;
698 }
699 
700 static const struct drbg_state_ops drbg_hmac_ops = {
701         .update         = drbg_hmac_update,
702         .generate       = drbg_hmac_generate,
703         .crypto_init    = drbg_init_hash_kernel,
704         .crypto_fini    = drbg_fini_hash_kernel,
705 };
706 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
707 
708 /******************************************************************
709  * Hash DRBG callback functions
710  ******************************************************************/
711 
712 #ifdef CONFIG_CRYPTO_DRBG_HASH
713 #define CRYPTO_DRBG_HASH_STRING "HASH "
714 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
715 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
716 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
717 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
718 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
719 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
720 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
721 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
722 
723 /*
724  * Increment buffer
725  *
726  * @dst buffer to increment
727  * @add value to add
728  */
729 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
730                                 const unsigned char *add, size_t addlen)
731 {
732         /* implied: dstlen > addlen */
733         unsigned char *dstptr;
734         const unsigned char *addptr;
735         unsigned int remainder = 0;
736         size_t len = addlen;
737 
738         dstptr = dst + (dstlen-1);
739         addptr = add + (addlen-1);
740         while (len) {
741                 remainder += *dstptr + *addptr;
742                 *dstptr = remainder & 0xff;
743                 remainder >>= 8;
744                 len--; dstptr--; addptr--;
745         }
746         len = dstlen - addlen;
747         while (len && remainder > 0) {
748                 remainder = *dstptr + 1;
749                 *dstptr = remainder & 0xff;
750                 remainder >>= 8;
751                 len--; dstptr--;
752         }
753 }
754 
755 /*
756  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
757  * interlinked, the scratchpad is used as follows:
758  * drbg_hash_update
759  *      start: drbg->scratchpad
760  *      length: drbg_statelen(drbg)
761  * drbg_hash_df:
762  *      start: drbg->scratchpad + drbg_statelen(drbg)
763  *      length: drbg_blocklen(drbg)
764  *
765  * drbg_hash_process_addtl uses the scratchpad, but fully completes
766  * before either of the functions mentioned before are invoked. Therefore,
767  * drbg_hash_process_addtl does not need to be specifically considered.
768  */
769 
770 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
771 static int drbg_hash_df(struct drbg_state *drbg,
772                         unsigned char *outval, size_t outlen,
773                         struct list_head *entropylist)
774 {
775         int ret = 0;
776         size_t len = 0;
777         unsigned char input[5];
778         unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
779         struct drbg_string data;
780 
781         /* 10.4.1 step 3 */
782         input[0] = 1;
783         drbg_cpu_to_be32((outlen * 8), &input[1]);
784 
785         /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
786         drbg_string_fill(&data, input, 5);
787         list_add(&data.list, entropylist);
788 
789         /* 10.4.1 step 4 */
790         while (len < outlen) {
791                 short blocklen = 0;
792                 /* 10.4.1 step 4.1 */
793                 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
794                 if (ret)
795                         goto out;
796                 /* 10.4.1 step 4.2 */
797                 input[0]++;
798                 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
799                             drbg_blocklen(drbg) : (outlen - len);
800                 memcpy(outval + len, tmp, blocklen);
801                 len += blocklen;
802         }
803 
804 out:
805         memset(tmp, 0, drbg_blocklen(drbg));
806         return ret;
807 }
808 
809 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
810 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
811                             int reseed)
812 {
813         int ret = 0;
814         struct drbg_string data1, data2;
815         LIST_HEAD(datalist);
816         LIST_HEAD(datalist2);
817         unsigned char *V = drbg->scratchpad;
818         unsigned char prefix = DRBG_PREFIX1;
819 
820         if (!seed)
821                 return -EINVAL;
822 
823         if (reseed) {
824                 /* 10.1.1.3 step 1 */
825                 memcpy(V, drbg->V, drbg_statelen(drbg));
826                 drbg_string_fill(&data1, &prefix, 1);
827                 list_add_tail(&data1.list, &datalist);
828                 drbg_string_fill(&data2, V, drbg_statelen(drbg));
829                 list_add_tail(&data2.list, &datalist);
830         }
831         list_splice_tail(seed, &datalist);
832 
833         /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
834         ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
835         if (ret)
836                 goto out;
837 
838         /* 10.1.1.2 / 10.1.1.3 step 4  */
839         prefix = DRBG_PREFIX0;
840         drbg_string_fill(&data1, &prefix, 1);
841         list_add_tail(&data1.list, &datalist2);
842         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
843         list_add_tail(&data2.list, &datalist2);
844         /* 10.1.1.2 / 10.1.1.3 step 4 */
845         ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
846 
847 out:
848         memset(drbg->scratchpad, 0, drbg_statelen(drbg));
849         return ret;
850 }
851 
852 /* processing of additional information string for Hash DRBG */
853 static int drbg_hash_process_addtl(struct drbg_state *drbg,
854                                    struct list_head *addtl)
855 {
856         int ret = 0;
857         struct drbg_string data1, data2;
858         LIST_HEAD(datalist);
859         unsigned char prefix = DRBG_PREFIX2;
860 
861         /* 10.1.1.4 step 2 */
862         if (!addtl || list_empty(addtl))
863                 return 0;
864 
865         /* 10.1.1.4 step 2a */
866         drbg_string_fill(&data1, &prefix, 1);
867         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
868         list_add_tail(&data1.list, &datalist);
869         list_add_tail(&data2.list, &datalist);
870         list_splice_tail(addtl, &datalist);
871         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
872         if (ret)
873                 goto out;
874 
875         /* 10.1.1.4 step 2b */
876         drbg_add_buf(drbg->V, drbg_statelen(drbg),
877                      drbg->scratchpad, drbg_blocklen(drbg));
878 
879 out:
880         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
881         return ret;
882 }
883 
884 /* Hashgen defined in 10.1.1.4 */
885 static int drbg_hash_hashgen(struct drbg_state *drbg,
886                              unsigned char *buf,
887                              unsigned int buflen)
888 {
889         int len = 0;
890         int ret = 0;
891         unsigned char *src = drbg->scratchpad;
892         unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
893         struct drbg_string data;
894         LIST_HEAD(datalist);
895 
896         /* 10.1.1.4 step hashgen 2 */
897         memcpy(src, drbg->V, drbg_statelen(drbg));
898 
899         drbg_string_fill(&data, src, drbg_statelen(drbg));
900         list_add_tail(&data.list, &datalist);
901         while (len < buflen) {
902                 unsigned int outlen = 0;
903                 /* 10.1.1.4 step hashgen 4.1 */
904                 ret = drbg_kcapi_hash(drbg, dst, &datalist);
905                 if (ret) {
906                         len = ret;
907                         goto out;
908                 }
909                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
910                           drbg_blocklen(drbg) : (buflen - len);
911                 /* 10.1.1.4 step hashgen 4.2 */
912                 memcpy(buf + len, dst, outlen);
913                 len += outlen;
914                 /* 10.1.1.4 hashgen step 4.3 */
915                 if (len < buflen)
916                         crypto_inc(src, drbg_statelen(drbg));
917         }
918 
919 out:
920         memset(drbg->scratchpad, 0,
921                (drbg_statelen(drbg) + drbg_blocklen(drbg)));
922         return len;
923 }
924 
925 /* generate function for Hash DRBG as defined in  10.1.1.4 */
926 static int drbg_hash_generate(struct drbg_state *drbg,
927                               unsigned char *buf, unsigned int buflen,
928                               struct list_head *addtl)
929 {
930         int len = 0;
931         int ret = 0;
932         union {
933                 unsigned char req[8];
934                 __be64 req_int;
935         } u;
936         unsigned char prefix = DRBG_PREFIX3;
937         struct drbg_string data1, data2;
938         LIST_HEAD(datalist);
939 
940         /* 10.1.1.4 step 2 */
941         ret = drbg_hash_process_addtl(drbg, addtl);
942         if (ret)
943                 return ret;
944         /* 10.1.1.4 step 3 */
945         len = drbg_hash_hashgen(drbg, buf, buflen);
946 
947         /* this is the value H as documented in 10.1.1.4 */
948         /* 10.1.1.4 step 4 */
949         drbg_string_fill(&data1, &prefix, 1);
950         list_add_tail(&data1.list, &datalist);
951         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
952         list_add_tail(&data2.list, &datalist);
953         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
954         if (ret) {
955                 len = ret;
956                 goto out;
957         }
958 
959         /* 10.1.1.4 step 5 */
960         drbg_add_buf(drbg->V, drbg_statelen(drbg),
961                      drbg->scratchpad, drbg_blocklen(drbg));
962         drbg_add_buf(drbg->V, drbg_statelen(drbg),
963                      drbg->C, drbg_statelen(drbg));
964         u.req_int = cpu_to_be64(drbg->reseed_ctr);
965         drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
966 
967 out:
968         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
969         return len;
970 }
971 
972 /*
973  * scratchpad usage: as update and generate are used isolated, both
974  * can use the scratchpad
975  */
976 static const struct drbg_state_ops drbg_hash_ops = {
977         .update         = drbg_hash_update,
978         .generate       = drbg_hash_generate,
979         .crypto_init    = drbg_init_hash_kernel,
980         .crypto_fini    = drbg_fini_hash_kernel,
981 };
982 #endif /* CONFIG_CRYPTO_DRBG_HASH */
983 
984 /******************************************************************
985  * Functions common for DRBG implementations
986  ******************************************************************/
987 
988 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
989                               int reseed)
990 {
991         int ret = drbg->d_ops->update(drbg, seed, reseed);
992 
993         if (ret)
994                 return ret;
995 
996         drbg->seeded = true;
997         /* 10.1.1.2 / 10.1.1.3 step 5 */
998         drbg->reseed_ctr = 1;
999 
1000         return ret;
1001 }
1002 
1003 static void drbg_async_seed(struct work_struct *work)
1004 {
1005         struct drbg_string data;
1006         LIST_HEAD(seedlist);
1007         struct drbg_state *drbg = container_of(work, struct drbg_state,
1008                                                seed_work);
1009         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1010         unsigned char entropy[32];
1011 
1012         BUG_ON(!entropylen);
1013         BUG_ON(entropylen > sizeof(entropy));
1014         get_random_bytes(entropy, entropylen);
1015 
1016         drbg_string_fill(&data, entropy, entropylen);
1017         list_add_tail(&data.list, &seedlist);
1018 
1019         mutex_lock(&drbg->drbg_mutex);
1020 
1021         /* If nonblocking pool is initialized, deactivate Jitter RNG */
1022         crypto_free_rng(drbg->jent);
1023         drbg->jent = NULL;
1024 
1025         /* Set seeded to false so that if __drbg_seed fails the
1026          * next generate call will trigger a reseed.
1027          */
1028         drbg->seeded = false;
1029 
1030         __drbg_seed(drbg, &seedlist, true);
1031 
1032         if (drbg->seeded)
1033                 drbg->reseed_threshold = drbg_max_requests(drbg);
1034 
1035         mutex_unlock(&drbg->drbg_mutex);
1036 
1037         memzero_explicit(entropy, entropylen);
1038 }
1039 
1040 /*
1041  * Seeding or reseeding of the DRBG
1042  *
1043  * @drbg: DRBG state struct
1044  * @pers: personalization / additional information buffer
1045  * @reseed: 0 for initial seed process, 1 for reseeding
1046  *
1047  * return:
1048  *      0 on success
1049  *      error value otherwise
1050  */
1051 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1052                      bool reseed)
1053 {
1054         int ret;
1055         unsigned char entropy[((32 + 16) * 2)];
1056         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1057         struct drbg_string data1;
1058         LIST_HEAD(seedlist);
1059 
1060         /* 9.1 / 9.2 / 9.3.1 step 3 */
1061         if (pers && pers->len > (drbg_max_addtl(drbg))) {
1062                 pr_devel("DRBG: personalization string too long %zu\n",
1063                          pers->len);
1064                 return -EINVAL;
1065         }
1066 
1067         if (list_empty(&drbg->test_data.list)) {
1068                 drbg_string_fill(&data1, drbg->test_data.buf,
1069                                  drbg->test_data.len);
1070                 pr_devel("DRBG: using test entropy\n");
1071         } else {
1072                 /*
1073                  * Gather entropy equal to the security strength of the DRBG.
1074                  * With a derivation function, a nonce is required in addition
1075                  * to the entropy. A nonce must be at least 1/2 of the security
1076                  * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1077                  * of the strength. The consideration of a nonce is only
1078                  * applicable during initial seeding.
1079                  */
1080                 BUG_ON(!entropylen);
1081                 if (!reseed)
1082                         entropylen = ((entropylen + 1) / 2) * 3;
1083                 BUG_ON((entropylen * 2) > sizeof(entropy));
1084 
1085                 /* Get seed from in-kernel /dev/urandom */
1086                 get_random_bytes(entropy, entropylen);
1087 
1088                 if (!drbg->jent) {
1089                         drbg_string_fill(&data1, entropy, entropylen);
1090                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1091                                  entropylen);
1092                 } else {
1093                         /* Get seed from Jitter RNG */
1094                         ret = crypto_rng_get_bytes(drbg->jent,
1095                                                    entropy + entropylen,
1096                                                    entropylen);
1097                         if (ret) {
1098                                 pr_devel("DRBG: jent failed with %d\n", ret);
1099                                 return ret;
1100                         }
1101 
1102                         drbg_string_fill(&data1, entropy, entropylen * 2);
1103                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1104                                  entropylen * 2);
1105                 }
1106         }
1107         list_add_tail(&data1.list, &seedlist);
1108 
1109         /*
1110          * concatenation of entropy with personalization str / addtl input)
1111          * the variable pers is directly handed in by the caller, so check its
1112          * contents whether it is appropriate
1113          */
1114         if (pers && pers->buf && 0 < pers->len) {
1115                 list_add_tail(&pers->list, &seedlist);
1116                 pr_devel("DRBG: using personalization string\n");
1117         }
1118 
1119         if (!reseed) {
1120                 memset(drbg->V, 0, drbg_statelen(drbg));
1121                 memset(drbg->C, 0, drbg_statelen(drbg));
1122         }
1123 
1124         ret = __drbg_seed(drbg, &seedlist, reseed);
1125 
1126         memzero_explicit(entropy, entropylen * 2);
1127 
1128         return ret;
1129 }
1130 
1131 /* Free all substructures in a DRBG state without the DRBG state structure */
1132 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1133 {
1134         if (!drbg)
1135                 return;
1136         kzfree(drbg->V);
1137         drbg->Vbuf = NULL;
1138         kzfree(drbg->C);
1139         drbg->Cbuf = NULL;
1140         kzfree(drbg->scratchpadbuf);
1141         drbg->scratchpadbuf = NULL;
1142         drbg->reseed_ctr = 0;
1143         drbg->d_ops = NULL;
1144         drbg->core = NULL;
1145 }
1146 
1147 /*
1148  * Allocate all sub-structures for a DRBG state.
1149  * The DRBG state structure must already be allocated.
1150  */
1151 static inline int drbg_alloc_state(struct drbg_state *drbg)
1152 {
1153         int ret = -ENOMEM;
1154         unsigned int sb_size = 0;
1155 
1156         switch (drbg->core->flags & DRBG_TYPE_MASK) {
1157 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1158         case DRBG_HMAC:
1159                 drbg->d_ops = &drbg_hmac_ops;
1160                 break;
1161 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1162 #ifdef CONFIG_CRYPTO_DRBG_HASH
1163         case DRBG_HASH:
1164                 drbg->d_ops = &drbg_hash_ops;
1165                 break;
1166 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1167 #ifdef CONFIG_CRYPTO_DRBG_CTR
1168         case DRBG_CTR:
1169                 drbg->d_ops = &drbg_ctr_ops;
1170                 break;
1171 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1172         default:
1173                 ret = -EOPNOTSUPP;
1174                 goto err;
1175         }
1176 
1177         ret = drbg->d_ops->crypto_init(drbg);
1178         if (ret < 0)
1179                 goto err;
1180 
1181         drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1182         if (!drbg->Vbuf) {
1183                 ret = -ENOMEM;
1184                 goto fini;
1185         }
1186         drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1187         drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1188         if (!drbg->Cbuf) {
1189                 ret = -ENOMEM;
1190                 goto fini;
1191         }
1192         drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1193         /* scratchpad is only generated for CTR and Hash */
1194         if (drbg->core->flags & DRBG_HMAC)
1195                 sb_size = 0;
1196         else if (drbg->core->flags & DRBG_CTR)
1197                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1198                           drbg_statelen(drbg) + /* df_data */
1199                           drbg_blocklen(drbg) + /* pad */
1200                           drbg_blocklen(drbg) + /* iv */
1201                           drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1202         else
1203                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1204 
1205         if (0 < sb_size) {
1206                 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1207                 if (!drbg->scratchpadbuf) {
1208                         ret = -ENOMEM;
1209                         goto fini;
1210                 }
1211                 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1212         }
1213 
1214         return 0;
1215 
1216 fini:
1217         drbg->d_ops->crypto_fini(drbg);
1218 err:
1219         drbg_dealloc_state(drbg);
1220         return ret;
1221 }
1222 
1223 /*************************************************************************
1224  * DRBG interface functions
1225  *************************************************************************/
1226 
1227 /*
1228  * DRBG generate function as required by SP800-90A - this function
1229  * generates random numbers
1230  *
1231  * @drbg DRBG state handle
1232  * @buf Buffer where to store the random numbers -- the buffer must already
1233  *      be pre-allocated by caller
1234  * @buflen Length of output buffer - this value defines the number of random
1235  *         bytes pulled from DRBG
1236  * @addtl Additional input that is mixed into state, may be NULL -- note
1237  *        the entropy is pulled by the DRBG internally unconditionally
1238  *        as defined in SP800-90A. The additional input is mixed into
1239  *        the state in addition to the pulled entropy.
1240  *
1241  * return: 0 when all bytes are generated; < 0 in case of an error
1242  */
1243 static int drbg_generate(struct drbg_state *drbg,
1244                          unsigned char *buf, unsigned int buflen,
1245                          struct drbg_string *addtl)
1246 {
1247         int len = 0;
1248         LIST_HEAD(addtllist);
1249 
1250         if (!drbg->core) {
1251                 pr_devel("DRBG: not yet seeded\n");
1252                 return -EINVAL;
1253         }
1254         if (0 == buflen || !buf) {
1255                 pr_devel("DRBG: no output buffer provided\n");
1256                 return -EINVAL;
1257         }
1258         if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1259                 pr_devel("DRBG: wrong format of additional information\n");
1260                 return -EINVAL;
1261         }
1262 
1263         /* 9.3.1 step 2 */
1264         len = -EINVAL;
1265         if (buflen > (drbg_max_request_bytes(drbg))) {
1266                 pr_devel("DRBG: requested random numbers too large %u\n",
1267                          buflen);
1268                 goto err;
1269         }
1270 
1271         /* 9.3.1 step 3 is implicit with the chosen DRBG */
1272 
1273         /* 9.3.1 step 4 */
1274         if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1275                 pr_devel("DRBG: additional information string too long %zu\n",
1276                          addtl->len);
1277                 goto err;
1278         }
1279         /* 9.3.1 step 5 is implicit with the chosen DRBG */
1280 
1281         /*
1282          * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1283          * here. The spec is a bit convoluted here, we make it simpler.
1284          */
1285         if (drbg->reseed_threshold < drbg->reseed_ctr)
1286                 drbg->seeded = false;
1287 
1288         if (drbg->pr || !drbg->seeded) {
1289                 pr_devel("DRBG: reseeding before generation (prediction "
1290                          "resistance: %s, state %s)\n",
1291                          drbg->pr ? "true" : "false",
1292                          drbg->seeded ? "seeded" : "unseeded");
1293                 /* 9.3.1 steps 7.1 through 7.3 */
1294                 len = drbg_seed(drbg, addtl, true);
1295                 if (len)
1296                         goto err;
1297                 /* 9.3.1 step 7.4 */
1298                 addtl = NULL;
1299         }
1300 
1301         if (addtl && 0 < addtl->len)
1302                 list_add_tail(&addtl->list, &addtllist);
1303         /* 9.3.1 step 8 and 10 */
1304         len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1305 
1306         /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1307         drbg->reseed_ctr++;
1308         if (0 >= len)
1309                 goto err;
1310 
1311         /*
1312          * Section 11.3.3 requires to re-perform self tests after some
1313          * generated random numbers. The chosen value after which self
1314          * test is performed is arbitrary, but it should be reasonable.
1315          * However, we do not perform the self tests because of the following
1316          * reasons: it is mathematically impossible that the initial self tests
1317          * were successfully and the following are not. If the initial would
1318          * pass and the following would not, the kernel integrity is violated.
1319          * In this case, the entire kernel operation is questionable and it
1320          * is unlikely that the integrity violation only affects the
1321          * correct operation of the DRBG.
1322          *
1323          * Albeit the following code is commented out, it is provided in
1324          * case somebody has a need to implement the test of 11.3.3.
1325          */
1326 #if 0
1327         if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1328                 int err = 0;
1329                 pr_devel("DRBG: start to perform self test\n");
1330                 if (drbg->core->flags & DRBG_HMAC)
1331                         err = alg_test("drbg_pr_hmac_sha256",
1332                                        "drbg_pr_hmac_sha256", 0, 0);
1333                 else if (drbg->core->flags & DRBG_CTR)
1334                         err = alg_test("drbg_pr_ctr_aes128",
1335                                        "drbg_pr_ctr_aes128", 0, 0);
1336                 else
1337                         err = alg_test("drbg_pr_sha256",
1338                                        "drbg_pr_sha256", 0, 0);
1339                 if (err) {
1340                         pr_err("DRBG: periodical self test failed\n");
1341                         /*
1342                          * uninstantiate implies that from now on, only errors
1343                          * are returned when reusing this DRBG cipher handle
1344                          */
1345                         drbg_uninstantiate(drbg);
1346                         return 0;
1347                 } else {
1348                         pr_devel("DRBG: self test successful\n");
1349                 }
1350         }
1351 #endif
1352 
1353         /*
1354          * All operations were successful, return 0 as mandated by
1355          * the kernel crypto API interface.
1356          */
1357         len = 0;
1358 err:
1359         return len;
1360 }
1361 
1362 /*
1363  * Wrapper around drbg_generate which can pull arbitrary long strings
1364  * from the DRBG without hitting the maximum request limitation.
1365  *
1366  * Parameters: see drbg_generate
1367  * Return codes: see drbg_generate -- if one drbg_generate request fails,
1368  *               the entire drbg_generate_long request fails
1369  */
1370 static int drbg_generate_long(struct drbg_state *drbg,
1371                               unsigned char *buf, unsigned int buflen,
1372                               struct drbg_string *addtl)
1373 {
1374         unsigned int len = 0;
1375         unsigned int slice = 0;
1376         do {
1377                 int err = 0;
1378                 unsigned int chunk = 0;
1379                 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1380                 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1381                 mutex_lock(&drbg->drbg_mutex);
1382                 err = drbg_generate(drbg, buf + len, chunk, addtl);
1383                 mutex_unlock(&drbg->drbg_mutex);
1384                 if (0 > err)
1385                         return err;
1386                 len += chunk;
1387         } while (slice > 0 && (len < buflen));
1388         return 0;
1389 }
1390 
1391 static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1392 {
1393         struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1394                                                random_ready);
1395 
1396         schedule_work(&drbg->seed_work);
1397 }
1398 
1399 static int drbg_prepare_hrng(struct drbg_state *drbg)
1400 {
1401         int err;
1402 
1403         /* We do not need an HRNG in test mode. */
1404         if (list_empty(&drbg->test_data.list))
1405                 return 0;
1406 
1407         INIT_WORK(&drbg->seed_work, drbg_async_seed);
1408 
1409         drbg->random_ready.owner = THIS_MODULE;
1410         drbg->random_ready.func = drbg_schedule_async_seed;
1411 
1412         err = add_random_ready_callback(&drbg->random_ready);
1413 
1414         switch (err) {
1415         case 0:
1416                 break;
1417 
1418         case -EALREADY:
1419                 err = 0;
1420                 /* fall through */
1421 
1422         default:
1423                 drbg->random_ready.func = NULL;
1424                 return err;
1425         }
1426 
1427         drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1428 
1429         /*
1430          * Require frequent reseeds until the seed source is fully
1431          * initialized.
1432          */
1433         drbg->reseed_threshold = 50;
1434 
1435         return err;
1436 }
1437 
1438 /*
1439  * DRBG instantiation function as required by SP800-90A - this function
1440  * sets up the DRBG handle, performs the initial seeding and all sanity
1441  * checks required by SP800-90A
1442  *
1443  * @drbg memory of state -- if NULL, new memory is allocated
1444  * @pers Personalization string that is mixed into state, may be NULL -- note
1445  *       the entropy is pulled by the DRBG internally unconditionally
1446  *       as defined in SP800-90A. The additional input is mixed into
1447  *       the state in addition to the pulled entropy.
1448  * @coreref reference to core
1449  * @pr prediction resistance enabled
1450  *
1451  * return
1452  *      0 on success
1453  *      error value otherwise
1454  */
1455 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1456                             int coreref, bool pr)
1457 {
1458         int ret;
1459         bool reseed = true;
1460 
1461         pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1462                  "%s\n", coreref, pr ? "enabled" : "disabled");
1463         mutex_lock(&drbg->drbg_mutex);
1464 
1465         /* 9.1 step 1 is implicit with the selected DRBG type */
1466 
1467         /*
1468          * 9.1 step 2 is implicit as caller can select prediction resistance
1469          * and the flag is copied into drbg->flags --
1470          * all DRBG types support prediction resistance
1471          */
1472 
1473         /* 9.1 step 4 is implicit in  drbg_sec_strength */
1474 
1475         if (!drbg->core) {
1476                 drbg->core = &drbg_cores[coreref];
1477                 drbg->pr = pr;
1478                 drbg->seeded = false;
1479                 drbg->reseed_threshold = drbg_max_requests(drbg);
1480 
1481                 ret = drbg_alloc_state(drbg);
1482                 if (ret)
1483                         goto unlock;
1484 
1485                 ret = drbg_prepare_hrng(drbg);
1486                 if (ret)
1487                         goto free_everything;
1488 
1489                 if (IS_ERR(drbg->jent)) {
1490                         ret = PTR_ERR(drbg->jent);
1491                         drbg->jent = NULL;
1492                         if (fips_enabled || ret != -ENOENT)
1493                                 goto free_everything;
1494                         pr_info("DRBG: Continuing without Jitter RNG\n");
1495                 }
1496 
1497                 reseed = false;
1498         }
1499 
1500         ret = drbg_seed(drbg, pers, reseed);
1501 
1502         if (ret && !reseed)
1503                 goto free_everything;
1504 
1505         mutex_unlock(&drbg->drbg_mutex);
1506         return ret;
1507 
1508 unlock:
1509         mutex_unlock(&drbg->drbg_mutex);
1510         return ret;
1511 
1512 free_everything:
1513         mutex_unlock(&drbg->drbg_mutex);
1514         drbg_uninstantiate(drbg);
1515         return ret;
1516 }
1517 
1518 /*
1519  * DRBG uninstantiate function as required by SP800-90A - this function
1520  * frees all buffers and the DRBG handle
1521  *
1522  * @drbg DRBG state handle
1523  *
1524  * return
1525  *      0 on success
1526  */
1527 static int drbg_uninstantiate(struct drbg_state *drbg)
1528 {
1529         if (drbg->random_ready.func) {
1530                 del_random_ready_callback(&drbg->random_ready);
1531                 cancel_work_sync(&drbg->seed_work);
1532                 crypto_free_rng(drbg->jent);
1533                 drbg->jent = NULL;
1534         }
1535 
1536         if (drbg->d_ops)
1537                 drbg->d_ops->crypto_fini(drbg);
1538         drbg_dealloc_state(drbg);
1539         /* no scrubbing of test_data -- this shall survive an uninstantiate */
1540         return 0;
1541 }
1542 
1543 /*
1544  * Helper function for setting the test data in the DRBG
1545  *
1546  * @drbg DRBG state handle
1547  * @data test data
1548  * @len test data length
1549  */
1550 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1551                                    const u8 *data, unsigned int len)
1552 {
1553         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1554 
1555         mutex_lock(&drbg->drbg_mutex);
1556         drbg_string_fill(&drbg->test_data, data, len);
1557         mutex_unlock(&drbg->drbg_mutex);
1558 }
1559 
1560 /***************************************************************
1561  * Kernel crypto API cipher invocations requested by DRBG
1562  ***************************************************************/
1563 
1564 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1565 struct sdesc {
1566         struct shash_desc shash;
1567         char ctx[];
1568 };
1569 
1570 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1571 {
1572         struct sdesc *sdesc;
1573         struct crypto_shash *tfm;
1574 
1575         tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1576         if (IS_ERR(tfm)) {
1577                 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1578                                 drbg->core->backend_cra_name);
1579                 return PTR_ERR(tfm);
1580         }
1581         BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1582         sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1583                         GFP_KERNEL);
1584         if (!sdesc) {
1585                 crypto_free_shash(tfm);
1586                 return -ENOMEM;
1587         }
1588 
1589         sdesc->shash.tfm = tfm;
1590         sdesc->shash.flags = 0;
1591         drbg->priv_data = sdesc;
1592 
1593         return crypto_shash_alignmask(tfm);
1594 }
1595 
1596 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1597 {
1598         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1599         if (sdesc) {
1600                 crypto_free_shash(sdesc->shash.tfm);
1601                 kzfree(sdesc);
1602         }
1603         drbg->priv_data = NULL;
1604         return 0;
1605 }
1606 
1607 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1608                                   const unsigned char *key)
1609 {
1610         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1611 
1612         crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1613 }
1614 
1615 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1616                            const struct list_head *in)
1617 {
1618         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1619         struct drbg_string *input = NULL;
1620 
1621         crypto_shash_init(&sdesc->shash);
1622         list_for_each_entry(input, in, list)
1623                 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1624         return crypto_shash_final(&sdesc->shash, outval);
1625 }
1626 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1627 
1628 #ifdef CONFIG_CRYPTO_DRBG_CTR
1629 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1630 {
1631         struct crypto_cipher *tfm =
1632                 (struct crypto_cipher *)drbg->priv_data;
1633         if (tfm)
1634                 crypto_free_cipher(tfm);
1635         drbg->priv_data = NULL;
1636 
1637         if (drbg->ctr_handle)
1638                 crypto_free_skcipher(drbg->ctr_handle);
1639         drbg->ctr_handle = NULL;
1640 
1641         if (drbg->ctr_req)
1642                 skcipher_request_free(drbg->ctr_req);
1643         drbg->ctr_req = NULL;
1644 
1645         kfree(drbg->ctr_null_value_buf);
1646         drbg->ctr_null_value = NULL;
1647 
1648         kfree(drbg->outscratchpadbuf);
1649         drbg->outscratchpadbuf = NULL;
1650 
1651         return 0;
1652 }
1653 
1654 static void drbg_skcipher_cb(struct crypto_async_request *req, int error)
1655 {
1656         struct drbg_state *drbg = req->data;
1657 
1658         if (error == -EINPROGRESS)
1659                 return;
1660         drbg->ctr_async_err = error;
1661         complete(&drbg->ctr_completion);
1662 }
1663 
1664 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1665 {
1666         struct crypto_cipher *tfm;
1667         struct crypto_skcipher *sk_tfm;
1668         struct skcipher_request *req;
1669         unsigned int alignmask;
1670         char ctr_name[CRYPTO_MAX_ALG_NAME];
1671 
1672         tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1673         if (IS_ERR(tfm)) {
1674                 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1675                                 drbg->core->backend_cra_name);
1676                 return PTR_ERR(tfm);
1677         }
1678         BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1679         drbg->priv_data = tfm;
1680 
1681         if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1682             drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1683                 drbg_fini_sym_kernel(drbg);
1684                 return -EINVAL;
1685         }
1686         sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1687         if (IS_ERR(sk_tfm)) {
1688                 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1689                                 ctr_name);
1690                 drbg_fini_sym_kernel(drbg);
1691                 return PTR_ERR(sk_tfm);
1692         }
1693         drbg->ctr_handle = sk_tfm;
1694 
1695         req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1696         if (!req) {
1697                 pr_info("DRBG: could not allocate request queue\n");
1698                 drbg_fini_sym_kernel(drbg);
1699                 return -ENOMEM;
1700         }
1701         drbg->ctr_req = req;
1702         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
1703                                         drbg_skcipher_cb, drbg);
1704 
1705         alignmask = crypto_skcipher_alignmask(sk_tfm);
1706         drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask,
1707                                            GFP_KERNEL);
1708         if (!drbg->ctr_null_value_buf) {
1709                 drbg_fini_sym_kernel(drbg);
1710                 return -ENOMEM;
1711         }
1712         drbg->ctr_null_value = (u8 *)PTR_ALIGN(drbg->ctr_null_value_buf,
1713                                                alignmask + 1);
1714 
1715         drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1716                                          GFP_KERNEL);
1717         if (!drbg->outscratchpadbuf) {
1718                 drbg_fini_sym_kernel(drbg);
1719                 return -ENOMEM;
1720         }
1721         drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1722                                               alignmask + 1);
1723 
1724         return alignmask;
1725 }
1726 
1727 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1728                                  const unsigned char *key)
1729 {
1730         struct crypto_cipher *tfm =
1731                 (struct crypto_cipher *)drbg->priv_data;
1732 
1733         crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1734 }
1735 
1736 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1737                           const struct drbg_string *in)
1738 {
1739         struct crypto_cipher *tfm =
1740                 (struct crypto_cipher *)drbg->priv_data;
1741 
1742         /* there is only component in *in */
1743         BUG_ON(in->len < drbg_blocklen(drbg));
1744         crypto_cipher_encrypt_one(tfm, outval, in->buf);
1745         return 0;
1746 }
1747 
1748 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1749                               u8 *inbuf, u32 inlen,
1750                               u8 *outbuf, u32 outlen)
1751 {
1752         struct scatterlist sg_in;
1753         int ret;
1754 
1755         sg_init_one(&sg_in, inbuf, inlen);
1756 
1757         while (outlen) {
1758                 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1759                 struct scatterlist sg_out;
1760 
1761                 /* Output buffer may not be valid for SGL, use scratchpad */
1762                 sg_init_one(&sg_out, drbg->outscratchpad, cryptlen);
1763                 skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,
1764                                            cryptlen, drbg->V);
1765                 ret = crypto_skcipher_encrypt(drbg->ctr_req);
1766                 switch (ret) {
1767                 case 0:
1768                         break;
1769                 case -EINPROGRESS:
1770                 case -EBUSY:
1771                         ret = wait_for_completion_interruptible(
1772                                 &drbg->ctr_completion);
1773                         if (!ret && !drbg->ctr_async_err) {
1774                                 reinit_completion(&drbg->ctr_completion);
1775                                 break;
1776                         }
1777                 default:
1778                         goto out;
1779                 }
1780                 init_completion(&drbg->ctr_completion);
1781 
1782                 memcpy(outbuf, drbg->outscratchpad, cryptlen);
1783 
1784                 outlen -= cryptlen;
1785                 outbuf += cryptlen;
1786         }
1787         ret = 0;
1788 
1789 out:
1790         memzero_explicit(drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1791         return ret;
1792 }
1793 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1794 
1795 /***************************************************************
1796  * Kernel crypto API interface to register DRBG
1797  ***************************************************************/
1798 
1799 /*
1800  * Look up the DRBG flags by given kernel crypto API cra_name
1801  * The code uses the drbg_cores definition to do this
1802  *
1803  * @cra_name kernel crypto API cra_name
1804  * @coreref reference to integer which is filled with the pointer to
1805  *  the applicable core
1806  * @pr reference for setting prediction resistance
1807  *
1808  * return: flags
1809  */
1810 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1811                                          int *coreref, bool *pr)
1812 {
1813         int i = 0;
1814         size_t start = 0;
1815         int len = 0;
1816 
1817         *pr = true;
1818         /* disassemble the names */
1819         if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1820                 start = 10;
1821                 *pr = false;
1822         } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1823                 start = 8;
1824         } else {
1825                 return;
1826         }
1827 
1828         /* remove the first part */
1829         len = strlen(cra_driver_name) - start;
1830         for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1831                 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1832                             len)) {
1833                         *coreref = i;
1834                         return;
1835                 }
1836         }
1837 }
1838 
1839 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1840 {
1841         struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1842 
1843         mutex_init(&drbg->drbg_mutex);
1844 
1845         return 0;
1846 }
1847 
1848 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1849 {
1850         drbg_uninstantiate(crypto_tfm_ctx(tfm));
1851 }
1852 
1853 /*
1854  * Generate random numbers invoked by the kernel crypto API:
1855  * The API of the kernel crypto API is extended as follows:
1856  *
1857  * src is additional input supplied to the RNG.
1858  * slen is the length of src.
1859  * dst is the output buffer where random data is to be stored.
1860  * dlen is the length of dst.
1861  */
1862 static int drbg_kcapi_random(struct crypto_rng *tfm,
1863                              const u8 *src, unsigned int slen,
1864                              u8 *dst, unsigned int dlen)
1865 {
1866         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1867         struct drbg_string *addtl = NULL;
1868         struct drbg_string string;
1869 
1870         if (slen) {
1871                 /* linked list variable is now local to allow modification */
1872                 drbg_string_fill(&string, src, slen);
1873                 addtl = &string;
1874         }
1875 
1876         return drbg_generate_long(drbg, dst, dlen, addtl);
1877 }
1878 
1879 /*
1880  * Seed the DRBG invoked by the kernel crypto API
1881  */
1882 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1883                            const u8 *seed, unsigned int slen)
1884 {
1885         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1886         struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1887         bool pr = false;
1888         struct drbg_string string;
1889         struct drbg_string *seed_string = NULL;
1890         int coreref = 0;
1891 
1892         drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1893                               &pr);
1894         if (0 < slen) {
1895                 drbg_string_fill(&string, seed, slen);
1896                 seed_string = &string;
1897         }
1898 
1899         return drbg_instantiate(drbg, seed_string, coreref, pr);
1900 }
1901 
1902 /***************************************************************
1903  * Kernel module: code to load the module
1904  ***************************************************************/
1905 
1906 /*
1907  * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1908  * of the error handling.
1909  *
1910  * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1911  * as seed source of get_random_bytes does not fail.
1912  *
1913  * Note 2: There is no sensible way of testing the reseed counter
1914  * enforcement, so skip it.
1915  */
1916 static inline int __init drbg_healthcheck_sanity(void)
1917 {
1918         int len = 0;
1919 #define OUTBUFLEN 16
1920         unsigned char buf[OUTBUFLEN];
1921         struct drbg_state *drbg = NULL;
1922         int ret = -EFAULT;
1923         int rc = -EFAULT;
1924         bool pr = false;
1925         int coreref = 0;
1926         struct drbg_string addtl;
1927         size_t max_addtllen, max_request_bytes;
1928 
1929         /* only perform test in FIPS mode */
1930         if (!fips_enabled)
1931                 return 0;
1932 
1933 #ifdef CONFIG_CRYPTO_DRBG_CTR
1934         drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1935 #elif defined CONFIG_CRYPTO_DRBG_HASH
1936         drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1937 #else
1938         drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1939 #endif
1940 
1941         drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1942         if (!drbg)
1943                 return -ENOMEM;
1944 
1945         mutex_init(&drbg->drbg_mutex);
1946         drbg->core = &drbg_cores[coreref];
1947         drbg->reseed_threshold = drbg_max_requests(drbg);
1948 
1949         /*
1950          * if the following tests fail, it is likely that there is a buffer
1951          * overflow as buf is much smaller than the requested or provided
1952          * string lengths -- in case the error handling does not succeed
1953          * we may get an OOPS. And we want to get an OOPS as this is a
1954          * grave bug.
1955          */
1956 
1957         max_addtllen = drbg_max_addtl(drbg);
1958         max_request_bytes = drbg_max_request_bytes(drbg);
1959         drbg_string_fill(&addtl, buf, max_addtllen + 1);
1960         /* overflow addtllen with additonal info string */
1961         len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1962         BUG_ON(0 < len);
1963         /* overflow max_bits */
1964         len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1965         BUG_ON(0 < len);
1966 
1967         /* overflow max addtllen with personalization string */
1968         ret = drbg_seed(drbg, &addtl, false);
1969         BUG_ON(0 == ret);
1970         /* all tests passed */
1971         rc = 0;
1972 
1973         pr_devel("DRBG: Sanity tests for failure code paths successfully "
1974                  "completed\n");
1975 
1976         kfree(drbg);
1977         return rc;
1978 }
1979 
1980 static struct rng_alg drbg_algs[22];
1981 
1982 /*
1983  * Fill the array drbg_algs used to register the different DRBGs
1984  * with the kernel crypto API. To fill the array, the information
1985  * from drbg_cores[] is used.
1986  */
1987 static inline void __init drbg_fill_array(struct rng_alg *alg,
1988                                           const struct drbg_core *core, int pr)
1989 {
1990         int pos = 0;
1991         static int priority = 200;
1992 
1993         memcpy(alg->base.cra_name, "stdrng", 6);
1994         if (pr) {
1995                 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1996                 pos = 8;
1997         } else {
1998                 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1999                 pos = 10;
2000         }
2001         memcpy(alg->base.cra_driver_name + pos, core->cra_name,
2002                strlen(core->cra_name));
2003 
2004         alg->base.cra_priority = priority;
2005         priority++;
2006         /*
2007          * If FIPS mode enabled, the selected DRBG shall have the
2008          * highest cra_priority over other stdrng instances to ensure
2009          * it is selected.
2010          */
2011         if (fips_enabled)
2012                 alg->base.cra_priority += 200;
2013 
2014         alg->base.cra_ctxsize   = sizeof(struct drbg_state);
2015         alg->base.cra_module    = THIS_MODULE;
2016         alg->base.cra_init      = drbg_kcapi_init;
2017         alg->base.cra_exit      = drbg_kcapi_cleanup;
2018         alg->generate           = drbg_kcapi_random;
2019         alg->seed               = drbg_kcapi_seed;
2020         alg->set_ent            = drbg_kcapi_set_entropy;
2021         alg->seedsize           = 0;
2022 }
2023 
2024 static int __init drbg_init(void)
2025 {
2026         unsigned int i = 0; /* pointer to drbg_algs */
2027         unsigned int j = 0; /* pointer to drbg_cores */
2028         int ret;
2029 
2030         ret = drbg_healthcheck_sanity();
2031         if (ret)
2032                 return ret;
2033 
2034         if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2035                 pr_info("DRBG: Cannot register all DRBG types"
2036                         "(slots needed: %zu, slots available: %zu)\n",
2037                         ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2038                 return -EFAULT;
2039         }
2040 
2041         /*
2042          * each DRBG definition can be used with PR and without PR, thus
2043          * we instantiate each DRBG in drbg_cores[] twice.
2044          *
2045          * As the order of placing them into the drbg_algs array matters
2046          * (the later DRBGs receive a higher cra_priority) we register the
2047          * prediction resistance DRBGs first as the should not be too
2048          * interesting.
2049          */
2050         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2051                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2052         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2053                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2054         return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2055 }
2056 
2057 static void __exit drbg_exit(void)
2058 {
2059         crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2060 }
2061 
2062 module_init(drbg_init);
2063 module_exit(drbg_exit);
2064 #ifndef CRYPTO_DRBG_HASH_STRING
2065 #define CRYPTO_DRBG_HASH_STRING ""
2066 #endif
2067 #ifndef CRYPTO_DRBG_HMAC_STRING
2068 #define CRYPTO_DRBG_HMAC_STRING ""
2069 #endif
2070 #ifndef CRYPTO_DRBG_CTR_STRING
2071 #define CRYPTO_DRBG_CTR_STRING ""
2072 #endif
2073 MODULE_LICENSE("GPL");
2074 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2075 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2076                    "using following cores: "
2077                    CRYPTO_DRBG_HASH_STRING
2078                    CRYPTO_DRBG_HMAC_STRING
2079                    CRYPTO_DRBG_CTR_STRING);
2080 MODULE_ALIAS_CRYPTO("stdrng");
2081 

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