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TOMOYO Linux Cross Reference
Linux/crypto/drbg.c

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  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_OUTSCRATCHLEN 256
265 
266 /* BCC function for CTR DRBG as defined in 10.4.3 */
267 static int drbg_ctr_bcc(struct drbg_state *drbg,
268                         unsigned char *out, const unsigned char *key,
269                         struct list_head *in)
270 {
271         int ret = 0;
272         struct drbg_string *curr = NULL;
273         struct drbg_string data;
274         short cnt = 0;
275 
276         drbg_string_fill(&data, out, drbg_blocklen(drbg));
277 
278         /* 10.4.3 step 2 / 4 */
279         drbg_kcapi_symsetkey(drbg, key);
280         list_for_each_entry(curr, in, list) {
281                 const unsigned char *pos = curr->buf;
282                 size_t len = curr->len;
283                 /* 10.4.3 step 4.1 */
284                 while (len) {
285                         /* 10.4.3 step 4.2 */
286                         if (drbg_blocklen(drbg) == cnt) {
287                                 cnt = 0;
288                                 ret = drbg_kcapi_sym(drbg, out, &data);
289                                 if (ret)
290                                         return ret;
291                         }
292                         out[cnt] ^= *pos;
293                         pos++;
294                         cnt++;
295                         len--;
296                 }
297         }
298         /* 10.4.3 step 4.2 for last block */
299         if (cnt)
300                 ret = drbg_kcapi_sym(drbg, out, &data);
301 
302         return ret;
303 }
304 
305 /*
306  * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
307  * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
308  * the scratchpad is used as follows:
309  * drbg_ctr_update:
310  *      temp
311  *              start: drbg->scratchpad
312  *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
313  *                      note: the cipher writing into this variable works
314  *                      blocklen-wise. Now, when the statelen is not a multiple
315  *                      of blocklen, the generateion loop below "spills over"
316  *                      by at most blocklen. Thus, we need to give sufficient
317  *                      memory.
318  *      df_data
319  *              start: drbg->scratchpad +
320  *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
321  *              length: drbg_statelen(drbg)
322  *
323  * drbg_ctr_df:
324  *      pad
325  *              start: df_data + drbg_statelen(drbg)
326  *              length: drbg_blocklen(drbg)
327  *      iv
328  *              start: pad + drbg_blocklen(drbg)
329  *              length: drbg_blocklen(drbg)
330  *      temp
331  *              start: iv + drbg_blocklen(drbg)
332  *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
333  *                      note: temp is the buffer that the BCC function operates
334  *                      on. BCC operates blockwise. drbg_statelen(drbg)
335  *                      is sufficient when the DRBG state length is a multiple
336  *                      of the block size. For AES192 (and maybe other ciphers)
337  *                      this is not correct and the length for temp is
338  *                      insufficient (yes, that also means for such ciphers,
339  *                      the final output of all BCC rounds are truncated).
340  *                      Therefore, add drbg_blocklen(drbg) to cover all
341  *                      possibilities.
342  */
343 
344 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
345 static int drbg_ctr_df(struct drbg_state *drbg,
346                        unsigned char *df_data, size_t bytes_to_return,
347                        struct list_head *seedlist)
348 {
349         int ret = -EFAULT;
350         unsigned char L_N[8];
351         /* S3 is input */
352         struct drbg_string S1, S2, S4, cipherin;
353         LIST_HEAD(bcc_list);
354         unsigned char *pad = df_data + drbg_statelen(drbg);
355         unsigned char *iv = pad + drbg_blocklen(drbg);
356         unsigned char *temp = iv + drbg_blocklen(drbg);
357         size_t padlen = 0;
358         unsigned int templen = 0;
359         /* 10.4.2 step 7 */
360         unsigned int i = 0;
361         /* 10.4.2 step 8 */
362         const unsigned char *K = (unsigned char *)
363                            "\x00\x01\x02\x03\x04\x05\x06\x07"
364                            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
365                            "\x10\x11\x12\x13\x14\x15\x16\x17"
366                            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
367         unsigned char *X;
368         size_t generated_len = 0;
369         size_t inputlen = 0;
370         struct drbg_string *seed = NULL;
371 
372         memset(pad, 0, drbg_blocklen(drbg));
373         memset(iv, 0, drbg_blocklen(drbg));
374 
375         /* 10.4.2 step 1 is implicit as we work byte-wise */
376 
377         /* 10.4.2 step 2 */
378         if ((512/8) < bytes_to_return)
379                 return -EINVAL;
380 
381         /* 10.4.2 step 2 -- calculate the entire length of all input data */
382         list_for_each_entry(seed, seedlist, list)
383                 inputlen += seed->len;
384         drbg_cpu_to_be32(inputlen, &L_N[0]);
385 
386         /* 10.4.2 step 3 */
387         drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
388 
389         /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
390         padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
391         /* wrap the padlen appropriately */
392         if (padlen)
393                 padlen = drbg_blocklen(drbg) - padlen;
394         /*
395          * pad / padlen contains the 0x80 byte and the following zero bytes.
396          * As the calculated padlen value only covers the number of zero
397          * bytes, this value has to be incremented by one for the 0x80 byte.
398          */
399         padlen++;
400         pad[0] = 0x80;
401 
402         /* 10.4.2 step 4 -- first fill the linked list and then order it */
403         drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
404         list_add_tail(&S1.list, &bcc_list);
405         drbg_string_fill(&S2, L_N, sizeof(L_N));
406         list_add_tail(&S2.list, &bcc_list);
407         list_splice_tail(seedlist, &bcc_list);
408         drbg_string_fill(&S4, pad, padlen);
409         list_add_tail(&S4.list, &bcc_list);
410 
411         /* 10.4.2 step 9 */
412         while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
413                 /*
414                  * 10.4.2 step 9.1 - the padding is implicit as the buffer
415                  * holds zeros after allocation -- even the increment of i
416                  * is irrelevant as the increment remains within length of i
417                  */
418                 drbg_cpu_to_be32(i, iv);
419                 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
420                 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
421                 if (ret)
422                         goto out;
423                 /* 10.4.2 step 9.3 */
424                 i++;
425                 templen += drbg_blocklen(drbg);
426         }
427 
428         /* 10.4.2 step 11 */
429         X = temp + (drbg_keylen(drbg));
430         drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
431 
432         /* 10.4.2 step 12: overwriting of outval is implemented in next step */
433 
434         /* 10.4.2 step 13 */
435         drbg_kcapi_symsetkey(drbg, temp);
436         while (generated_len < bytes_to_return) {
437                 short blocklen = 0;
438                 /*
439                  * 10.4.2 step 13.1: the truncation of the key length is
440                  * implicit as the key is only drbg_blocklen in size based on
441                  * the implementation of the cipher function callback
442                  */
443                 ret = drbg_kcapi_sym(drbg, X, &cipherin);
444                 if (ret)
445                         goto out;
446                 blocklen = (drbg_blocklen(drbg) <
447                                 (bytes_to_return - generated_len)) ?
448                             drbg_blocklen(drbg) :
449                                 (bytes_to_return - generated_len);
450                 /* 10.4.2 step 13.2 and 14 */
451                 memcpy(df_data + generated_len, X, blocklen);
452                 generated_len += blocklen;
453         }
454 
455         ret = 0;
456 
457 out:
458         memset(iv, 0, drbg_blocklen(drbg));
459         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
460         memset(pad, 0, drbg_blocklen(drbg));
461         return ret;
462 }
463 
464 /*
465  * update function of CTR DRBG as defined in 10.2.1.2
466  *
467  * The reseed variable has an enhanced meaning compared to the update
468  * functions of the other DRBGs as follows:
469  * 0 => initial seed from initialization
470  * 1 => reseed via drbg_seed
471  * 2 => first invocation from drbg_ctr_update when addtl is present. In
472  *      this case, the df_data scratchpad is not deleted so that it is
473  *      available for another calls to prevent calling the DF function
474  *      again.
475  * 3 => second invocation from drbg_ctr_update. When the update function
476  *      was called with addtl, the df_data memory already contains the
477  *      DFed addtl information and we do not need to call DF again.
478  */
479 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
480                            int reseed)
481 {
482         int ret = -EFAULT;
483         /* 10.2.1.2 step 1 */
484         unsigned char *temp = drbg->scratchpad;
485         unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
486                                  drbg_blocklen(drbg);
487 
488         if (3 > reseed)
489                 memset(df_data, 0, drbg_statelen(drbg));
490 
491         if (!reseed) {
492                 /*
493                  * The DRBG uses the CTR mode of the underlying AES cipher. The
494                  * CTR mode increments the counter value after the AES operation
495                  * but SP800-90A requires that the counter is incremented before
496                  * the AES operation. Hence, we increment it at the time we set
497                  * it by one.
498                  */
499                 crypto_inc(drbg->V, drbg_blocklen(drbg));
500 
501                 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
502                                              drbg_keylen(drbg));
503                 if (ret)
504                         goto out;
505         }
506 
507         /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
508         if (seed) {
509                 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
510                 if (ret)
511                         goto out;
512         }
513 
514         ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
515                                  temp, drbg_statelen(drbg));
516         if (ret)
517                 return ret;
518 
519         /* 10.2.1.2 step 5 */
520         ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
521                                      drbg_keylen(drbg));
522         if (ret)
523                 goto out;
524         /* 10.2.1.2 step 6 */
525         memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
526         /* See above: increment counter by one to compensate timing of CTR op */
527         crypto_inc(drbg->V, drbg_blocklen(drbg));
528         ret = 0;
529 
530 out:
531         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
532         if (2 != reseed)
533                 memset(df_data, 0, drbg_statelen(drbg));
534         return ret;
535 }
536 
537 /*
538  * scratchpad use: drbg_ctr_update is called independently from
539  * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
540  */
541 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
542 static int drbg_ctr_generate(struct drbg_state *drbg,
543                              unsigned char *buf, unsigned int buflen,
544                              struct list_head *addtl)
545 {
546         int ret;
547         int len = min_t(int, buflen, INT_MAX);
548 
549         /* 10.2.1.5.2 step 2 */
550         if (addtl && !list_empty(addtl)) {
551                 ret = drbg_ctr_update(drbg, addtl, 2);
552                 if (ret)
553                         return 0;
554         }
555 
556         /* 10.2.1.5.2 step 4.1 */
557         ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
558         if (ret)
559                 return ret;
560 
561         /* 10.2.1.5.2 step 6 */
562         ret = drbg_ctr_update(drbg, NULL, 3);
563         if (ret)
564                 len = ret;
565 
566         return len;
567 }
568 
569 static const struct drbg_state_ops drbg_ctr_ops = {
570         .update         = drbg_ctr_update,
571         .generate       = drbg_ctr_generate,
572         .crypto_init    = drbg_init_sym_kernel,
573         .crypto_fini    = drbg_fini_sym_kernel,
574 };
575 #endif /* CONFIG_CRYPTO_DRBG_CTR */
576 
577 /******************************************************************
578  * HMAC DRBG callback functions
579  ******************************************************************/
580 
581 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
582 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
583                            const struct list_head *in);
584 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
585                                   const unsigned char *key);
586 static int drbg_init_hash_kernel(struct drbg_state *drbg);
587 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
588 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
589 
590 #ifdef CONFIG_CRYPTO_DRBG_HMAC
591 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
592 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
593 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
594 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
595 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
596 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
597 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
598 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
599 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
600 
601 /* update function of HMAC DRBG as defined in 10.1.2.2 */
602 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
603                             int reseed)
604 {
605         int ret = -EFAULT;
606         int i = 0;
607         struct drbg_string seed1, seed2, vdata;
608         LIST_HEAD(seedlist);
609         LIST_HEAD(vdatalist);
610 
611         if (!reseed) {
612                 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
613                 memset(drbg->V, 1, drbg_statelen(drbg));
614                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
615         }
616 
617         drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
618         list_add_tail(&seed1.list, &seedlist);
619         /* buffer of seed2 will be filled in for loop below with one byte */
620         drbg_string_fill(&seed2, NULL, 1);
621         list_add_tail(&seed2.list, &seedlist);
622         /* input data of seed is allowed to be NULL at this point */
623         if (seed)
624                 list_splice_tail(seed, &seedlist);
625 
626         drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
627         list_add_tail(&vdata.list, &vdatalist);
628         for (i = 2; 0 < i; i--) {
629                 /* first round uses 0x0, second 0x1 */
630                 unsigned char prefix = DRBG_PREFIX0;
631                 if (1 == i)
632                         prefix = DRBG_PREFIX1;
633                 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
634                 seed2.buf = &prefix;
635                 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
636                 if (ret)
637                         return ret;
638                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
639 
640                 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
641                 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
642                 if (ret)
643                         return ret;
644 
645                 /* 10.1.2.2 step 3 */
646                 if (!seed)
647                         return ret;
648         }
649 
650         return 0;
651 }
652 
653 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
654 static int drbg_hmac_generate(struct drbg_state *drbg,
655                               unsigned char *buf,
656                               unsigned int buflen,
657                               struct list_head *addtl)
658 {
659         int len = 0;
660         int ret = 0;
661         struct drbg_string data;
662         LIST_HEAD(datalist);
663 
664         /* 10.1.2.5 step 2 */
665         if (addtl && !list_empty(addtl)) {
666                 ret = drbg_hmac_update(drbg, addtl, 1);
667                 if (ret)
668                         return ret;
669         }
670 
671         drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
672         list_add_tail(&data.list, &datalist);
673         while (len < buflen) {
674                 unsigned int outlen = 0;
675                 /* 10.1.2.5 step 4.1 */
676                 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
677                 if (ret)
678                         return ret;
679                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
680                           drbg_blocklen(drbg) : (buflen - len);
681 
682                 /* 10.1.2.5 step 4.2 */
683                 memcpy(buf + len, drbg->V, outlen);
684                 len += outlen;
685         }
686 
687         /* 10.1.2.5 step 6 */
688         if (addtl && !list_empty(addtl))
689                 ret = drbg_hmac_update(drbg, addtl, 1);
690         else
691                 ret = drbg_hmac_update(drbg, NULL, 1);
692         if (ret)
693                 return ret;
694 
695         return len;
696 }
697 
698 static const struct drbg_state_ops drbg_hmac_ops = {
699         .update         = drbg_hmac_update,
700         .generate       = drbg_hmac_generate,
701         .crypto_init    = drbg_init_hash_kernel,
702         .crypto_fini    = drbg_fini_hash_kernel,
703 };
704 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
705 
706 /******************************************************************
707  * Hash DRBG callback functions
708  ******************************************************************/
709 
710 #ifdef CONFIG_CRYPTO_DRBG_HASH
711 #define CRYPTO_DRBG_HASH_STRING "HASH "
712 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
713 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
714 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
715 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
716 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
717 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
718 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
719 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
720 
721 /*
722  * Increment buffer
723  *
724  * @dst buffer to increment
725  * @add value to add
726  */
727 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
728                                 const unsigned char *add, size_t addlen)
729 {
730         /* implied: dstlen > addlen */
731         unsigned char *dstptr;
732         const unsigned char *addptr;
733         unsigned int remainder = 0;
734         size_t len = addlen;
735 
736         dstptr = dst + (dstlen-1);
737         addptr = add + (addlen-1);
738         while (len) {
739                 remainder += *dstptr + *addptr;
740                 *dstptr = remainder & 0xff;
741                 remainder >>= 8;
742                 len--; dstptr--; addptr--;
743         }
744         len = dstlen - addlen;
745         while (len && remainder > 0) {
746                 remainder = *dstptr + 1;
747                 *dstptr = remainder & 0xff;
748                 remainder >>= 8;
749                 len--; dstptr--;
750         }
751 }
752 
753 /*
754  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
755  * interlinked, the scratchpad is used as follows:
756  * drbg_hash_update
757  *      start: drbg->scratchpad
758  *      length: drbg_statelen(drbg)
759  * drbg_hash_df:
760  *      start: drbg->scratchpad + drbg_statelen(drbg)
761  *      length: drbg_blocklen(drbg)
762  *
763  * drbg_hash_process_addtl uses the scratchpad, but fully completes
764  * before either of the functions mentioned before are invoked. Therefore,
765  * drbg_hash_process_addtl does not need to be specifically considered.
766  */
767 
768 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
769 static int drbg_hash_df(struct drbg_state *drbg,
770                         unsigned char *outval, size_t outlen,
771                         struct list_head *entropylist)
772 {
773         int ret = 0;
774         size_t len = 0;
775         unsigned char input[5];
776         unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
777         struct drbg_string data;
778 
779         /* 10.4.1 step 3 */
780         input[0] = 1;
781         drbg_cpu_to_be32((outlen * 8), &input[1]);
782 
783         /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
784         drbg_string_fill(&data, input, 5);
785         list_add(&data.list, entropylist);
786 
787         /* 10.4.1 step 4 */
788         while (len < outlen) {
789                 short blocklen = 0;
790                 /* 10.4.1 step 4.1 */
791                 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
792                 if (ret)
793                         goto out;
794                 /* 10.4.1 step 4.2 */
795                 input[0]++;
796                 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
797                             drbg_blocklen(drbg) : (outlen - len);
798                 memcpy(outval + len, tmp, blocklen);
799                 len += blocklen;
800         }
801 
802 out:
803         memset(tmp, 0, drbg_blocklen(drbg));
804         return ret;
805 }
806 
807 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
808 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
809                             int reseed)
810 {
811         int ret = 0;
812         struct drbg_string data1, data2;
813         LIST_HEAD(datalist);
814         LIST_HEAD(datalist2);
815         unsigned char *V = drbg->scratchpad;
816         unsigned char prefix = DRBG_PREFIX1;
817 
818         if (!seed)
819                 return -EINVAL;
820 
821         if (reseed) {
822                 /* 10.1.1.3 step 1 */
823                 memcpy(V, drbg->V, drbg_statelen(drbg));
824                 drbg_string_fill(&data1, &prefix, 1);
825                 list_add_tail(&data1.list, &datalist);
826                 drbg_string_fill(&data2, V, drbg_statelen(drbg));
827                 list_add_tail(&data2.list, &datalist);
828         }
829         list_splice_tail(seed, &datalist);
830 
831         /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
832         ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
833         if (ret)
834                 goto out;
835 
836         /* 10.1.1.2 / 10.1.1.3 step 4  */
837         prefix = DRBG_PREFIX0;
838         drbg_string_fill(&data1, &prefix, 1);
839         list_add_tail(&data1.list, &datalist2);
840         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
841         list_add_tail(&data2.list, &datalist2);
842         /* 10.1.1.2 / 10.1.1.3 step 4 */
843         ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
844 
845 out:
846         memset(drbg->scratchpad, 0, drbg_statelen(drbg));
847         return ret;
848 }
849 
850 /* processing of additional information string for Hash DRBG */
851 static int drbg_hash_process_addtl(struct drbg_state *drbg,
852                                    struct list_head *addtl)
853 {
854         int ret = 0;
855         struct drbg_string data1, data2;
856         LIST_HEAD(datalist);
857         unsigned char prefix = DRBG_PREFIX2;
858 
859         /* 10.1.1.4 step 2 */
860         if (!addtl || list_empty(addtl))
861                 return 0;
862 
863         /* 10.1.1.4 step 2a */
864         drbg_string_fill(&data1, &prefix, 1);
865         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
866         list_add_tail(&data1.list, &datalist);
867         list_add_tail(&data2.list, &datalist);
868         list_splice_tail(addtl, &datalist);
869         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
870         if (ret)
871                 goto out;
872 
873         /* 10.1.1.4 step 2b */
874         drbg_add_buf(drbg->V, drbg_statelen(drbg),
875                      drbg->scratchpad, drbg_blocklen(drbg));
876 
877 out:
878         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
879         return ret;
880 }
881 
882 /* Hashgen defined in 10.1.1.4 */
883 static int drbg_hash_hashgen(struct drbg_state *drbg,
884                              unsigned char *buf,
885                              unsigned int buflen)
886 {
887         int len = 0;
888         int ret = 0;
889         unsigned char *src = drbg->scratchpad;
890         unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
891         struct drbg_string data;
892         LIST_HEAD(datalist);
893 
894         /* 10.1.1.4 step hashgen 2 */
895         memcpy(src, drbg->V, drbg_statelen(drbg));
896 
897         drbg_string_fill(&data, src, drbg_statelen(drbg));
898         list_add_tail(&data.list, &datalist);
899         while (len < buflen) {
900                 unsigned int outlen = 0;
901                 /* 10.1.1.4 step hashgen 4.1 */
902                 ret = drbg_kcapi_hash(drbg, dst, &datalist);
903                 if (ret) {
904                         len = ret;
905                         goto out;
906                 }
907                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
908                           drbg_blocklen(drbg) : (buflen - len);
909                 /* 10.1.1.4 step hashgen 4.2 */
910                 memcpy(buf + len, dst, outlen);
911                 len += outlen;
912                 /* 10.1.1.4 hashgen step 4.3 */
913                 if (len < buflen)
914                         crypto_inc(src, drbg_statelen(drbg));
915         }
916 
917 out:
918         memset(drbg->scratchpad, 0,
919                (drbg_statelen(drbg) + drbg_blocklen(drbg)));
920         return len;
921 }
922 
923 /* generate function for Hash DRBG as defined in  10.1.1.4 */
924 static int drbg_hash_generate(struct drbg_state *drbg,
925                               unsigned char *buf, unsigned int buflen,
926                               struct list_head *addtl)
927 {
928         int len = 0;
929         int ret = 0;
930         union {
931                 unsigned char req[8];
932                 __be64 req_int;
933         } u;
934         unsigned char prefix = DRBG_PREFIX3;
935         struct drbg_string data1, data2;
936         LIST_HEAD(datalist);
937 
938         /* 10.1.1.4 step 2 */
939         ret = drbg_hash_process_addtl(drbg, addtl);
940         if (ret)
941                 return ret;
942         /* 10.1.1.4 step 3 */
943         len = drbg_hash_hashgen(drbg, buf, buflen);
944 
945         /* this is the value H as documented in 10.1.1.4 */
946         /* 10.1.1.4 step 4 */
947         drbg_string_fill(&data1, &prefix, 1);
948         list_add_tail(&data1.list, &datalist);
949         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
950         list_add_tail(&data2.list, &datalist);
951         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
952         if (ret) {
953                 len = ret;
954                 goto out;
955         }
956 
957         /* 10.1.1.4 step 5 */
958         drbg_add_buf(drbg->V, drbg_statelen(drbg),
959                      drbg->scratchpad, drbg_blocklen(drbg));
960         drbg_add_buf(drbg->V, drbg_statelen(drbg),
961                      drbg->C, drbg_statelen(drbg));
962         u.req_int = cpu_to_be64(drbg->reseed_ctr);
963         drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
964 
965 out:
966         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
967         return len;
968 }
969 
970 /*
971  * scratchpad usage: as update and generate are used isolated, both
972  * can use the scratchpad
973  */
974 static const struct drbg_state_ops drbg_hash_ops = {
975         .update         = drbg_hash_update,
976         .generate       = drbg_hash_generate,
977         .crypto_init    = drbg_init_hash_kernel,
978         .crypto_fini    = drbg_fini_hash_kernel,
979 };
980 #endif /* CONFIG_CRYPTO_DRBG_HASH */
981 
982 /******************************************************************
983  * Functions common for DRBG implementations
984  ******************************************************************/
985 
986 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
987                               int reseed)
988 {
989         int ret = drbg->d_ops->update(drbg, seed, reseed);
990 
991         if (ret)
992                 return ret;
993 
994         drbg->seeded = true;
995         /* 10.1.1.2 / 10.1.1.3 step 5 */
996         drbg->reseed_ctr = 1;
997 
998         return ret;
999 }
1000 
1001 static void drbg_async_seed(struct work_struct *work)
1002 {
1003         struct drbg_string data;
1004         LIST_HEAD(seedlist);
1005         struct drbg_state *drbg = container_of(work, struct drbg_state,
1006                                                seed_work);
1007         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1008         unsigned char entropy[32];
1009 
1010         BUG_ON(!entropylen);
1011         BUG_ON(entropylen > sizeof(entropy));
1012         get_random_bytes(entropy, entropylen);
1013 
1014         drbg_string_fill(&data, entropy, entropylen);
1015         list_add_tail(&data.list, &seedlist);
1016 
1017         mutex_lock(&drbg->drbg_mutex);
1018 
1019         /* If nonblocking pool is initialized, deactivate Jitter RNG */
1020         crypto_free_rng(drbg->jent);
1021         drbg->jent = NULL;
1022 
1023         /* Set seeded to false so that if __drbg_seed fails the
1024          * next generate call will trigger a reseed.
1025          */
1026         drbg->seeded = false;
1027 
1028         __drbg_seed(drbg, &seedlist, true);
1029 
1030         if (drbg->seeded)
1031                 drbg->reseed_threshold = drbg_max_requests(drbg);
1032 
1033         mutex_unlock(&drbg->drbg_mutex);
1034 
1035         memzero_explicit(entropy, entropylen);
1036 }
1037 
1038 /*
1039  * Seeding or reseeding of the DRBG
1040  *
1041  * @drbg: DRBG state struct
1042  * @pers: personalization / additional information buffer
1043  * @reseed: 0 for initial seed process, 1 for reseeding
1044  *
1045  * return:
1046  *      0 on success
1047  *      error value otherwise
1048  */
1049 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1050                      bool reseed)
1051 {
1052         int ret;
1053         unsigned char entropy[((32 + 16) * 2)];
1054         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1055         struct drbg_string data1;
1056         LIST_HEAD(seedlist);
1057 
1058         /* 9.1 / 9.2 / 9.3.1 step 3 */
1059         if (pers && pers->len > (drbg_max_addtl(drbg))) {
1060                 pr_devel("DRBG: personalization string too long %zu\n",
1061                          pers->len);
1062                 return -EINVAL;
1063         }
1064 
1065         if (list_empty(&drbg->test_data.list)) {
1066                 drbg_string_fill(&data1, drbg->test_data.buf,
1067                                  drbg->test_data.len);
1068                 pr_devel("DRBG: using test entropy\n");
1069         } else {
1070                 /*
1071                  * Gather entropy equal to the security strength of the DRBG.
1072                  * With a derivation function, a nonce is required in addition
1073                  * to the entropy. A nonce must be at least 1/2 of the security
1074                  * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1075                  * of the strength. The consideration of a nonce is only
1076                  * applicable during initial seeding.
1077                  */
1078                 BUG_ON(!entropylen);
1079                 if (!reseed)
1080                         entropylen = ((entropylen + 1) / 2) * 3;
1081                 BUG_ON((entropylen * 2) > sizeof(entropy));
1082 
1083                 /* Get seed from in-kernel /dev/urandom */
1084                 get_random_bytes(entropy, entropylen);
1085 
1086                 if (!drbg->jent) {
1087                         drbg_string_fill(&data1, entropy, entropylen);
1088                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1089                                  entropylen);
1090                 } else {
1091                         /* Get seed from Jitter RNG */
1092                         ret = crypto_rng_get_bytes(drbg->jent,
1093                                                    entropy + entropylen,
1094                                                    entropylen);
1095                         if (ret) {
1096                                 pr_devel("DRBG: jent failed with %d\n", ret);
1097                                 return ret;
1098                         }
1099 
1100                         drbg_string_fill(&data1, entropy, entropylen * 2);
1101                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1102                                  entropylen * 2);
1103                 }
1104         }
1105         list_add_tail(&data1.list, &seedlist);
1106 
1107         /*
1108          * concatenation of entropy with personalization str / addtl input)
1109          * the variable pers is directly handed in by the caller, so check its
1110          * contents whether it is appropriate
1111          */
1112         if (pers && pers->buf && 0 < pers->len) {
1113                 list_add_tail(&pers->list, &seedlist);
1114                 pr_devel("DRBG: using personalization string\n");
1115         }
1116 
1117         if (!reseed) {
1118                 memset(drbg->V, 0, drbg_statelen(drbg));
1119                 memset(drbg->C, 0, drbg_statelen(drbg));
1120         }
1121 
1122         ret = __drbg_seed(drbg, &seedlist, reseed);
1123 
1124         memzero_explicit(entropy, entropylen * 2);
1125 
1126         return ret;
1127 }
1128 
1129 /* Free all substructures in a DRBG state without the DRBG state structure */
1130 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1131 {
1132         if (!drbg)
1133                 return;
1134         kzfree(drbg->Vbuf);
1135         drbg->Vbuf = NULL;
1136         drbg->V = NULL;
1137         kzfree(drbg->Cbuf);
1138         drbg->Cbuf = NULL;
1139         drbg->C = 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->outscratchpadbuf);
1646         drbg->outscratchpadbuf = NULL;
1647 
1648         return 0;
1649 }
1650 
1651 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1652 {
1653         struct crypto_cipher *tfm;
1654         struct crypto_skcipher *sk_tfm;
1655         struct skcipher_request *req;
1656         unsigned int alignmask;
1657         char ctr_name[CRYPTO_MAX_ALG_NAME];
1658 
1659         tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1660         if (IS_ERR(tfm)) {
1661                 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1662                                 drbg->core->backend_cra_name);
1663                 return PTR_ERR(tfm);
1664         }
1665         BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1666         drbg->priv_data = tfm;
1667 
1668         if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1669             drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1670                 drbg_fini_sym_kernel(drbg);
1671                 return -EINVAL;
1672         }
1673         sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1674         if (IS_ERR(sk_tfm)) {
1675                 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1676                                 ctr_name);
1677                 drbg_fini_sym_kernel(drbg);
1678                 return PTR_ERR(sk_tfm);
1679         }
1680         drbg->ctr_handle = sk_tfm;
1681         crypto_init_wait(&drbg->ctr_wait);
1682 
1683         req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1684         if (!req) {
1685                 pr_info("DRBG: could not allocate request queue\n");
1686                 drbg_fini_sym_kernel(drbg);
1687                 return -ENOMEM;
1688         }
1689         drbg->ctr_req = req;
1690         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
1691                                                 CRYPTO_TFM_REQ_MAY_SLEEP,
1692                                         crypto_req_done, &drbg->ctr_wait);
1693 
1694         alignmask = crypto_skcipher_alignmask(sk_tfm);
1695         drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1696                                          GFP_KERNEL);
1697         if (!drbg->outscratchpadbuf) {
1698                 drbg_fini_sym_kernel(drbg);
1699                 return -ENOMEM;
1700         }
1701         drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1702                                               alignmask + 1);
1703 
1704         sg_init_table(&drbg->sg_in, 1);
1705         sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1706 
1707         return alignmask;
1708 }
1709 
1710 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1711                                  const unsigned char *key)
1712 {
1713         struct crypto_cipher *tfm =
1714                 (struct crypto_cipher *)drbg->priv_data;
1715 
1716         crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1717 }
1718 
1719 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1720                           const struct drbg_string *in)
1721 {
1722         struct crypto_cipher *tfm =
1723                 (struct crypto_cipher *)drbg->priv_data;
1724 
1725         /* there is only component in *in */
1726         BUG_ON(in->len < drbg_blocklen(drbg));
1727         crypto_cipher_encrypt_one(tfm, outval, in->buf);
1728         return 0;
1729 }
1730 
1731 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1732                               u8 *inbuf, u32 inlen,
1733                               u8 *outbuf, u32 outlen)
1734 {
1735         struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
1736         u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
1737         int ret;
1738 
1739         if (inbuf) {
1740                 /* Use caller-provided input buffer */
1741                 sg_set_buf(sg_in, inbuf, inlen);
1742         } else {
1743                 /* Use scratchpad for in-place operation */
1744                 inlen = scratchpad_use;
1745                 memset(drbg->outscratchpad, 0, scratchpad_use);
1746                 sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
1747         }
1748 
1749         while (outlen) {
1750                 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1751 
1752                 /* Output buffer may not be valid for SGL, use scratchpad */
1753                 skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,
1754                                            cryptlen, drbg->V);
1755                 ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
1756                                         &drbg->ctr_wait);
1757                 if (ret)
1758                         goto out;
1759 
1760                 crypto_init_wait(&drbg->ctr_wait);
1761 
1762                 memcpy(outbuf, drbg->outscratchpad, cryptlen);
1763                 memzero_explicit(drbg->outscratchpad, cryptlen);
1764 
1765                 outlen -= cryptlen;
1766                 outbuf += cryptlen;
1767         }
1768         ret = 0;
1769 
1770 out:
1771         return ret;
1772 }
1773 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1774 
1775 /***************************************************************
1776  * Kernel crypto API interface to register DRBG
1777  ***************************************************************/
1778 
1779 /*
1780  * Look up the DRBG flags by given kernel crypto API cra_name
1781  * The code uses the drbg_cores definition to do this
1782  *
1783  * @cra_name kernel crypto API cra_name
1784  * @coreref reference to integer which is filled with the pointer to
1785  *  the applicable core
1786  * @pr reference for setting prediction resistance
1787  *
1788  * return: flags
1789  */
1790 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1791                                          int *coreref, bool *pr)
1792 {
1793         int i = 0;
1794         size_t start = 0;
1795         int len = 0;
1796 
1797         *pr = true;
1798         /* disassemble the names */
1799         if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1800                 start = 10;
1801                 *pr = false;
1802         } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1803                 start = 8;
1804         } else {
1805                 return;
1806         }
1807 
1808         /* remove the first part */
1809         len = strlen(cra_driver_name) - start;
1810         for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1811                 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1812                             len)) {
1813                         *coreref = i;
1814                         return;
1815                 }
1816         }
1817 }
1818 
1819 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1820 {
1821         struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1822 
1823         mutex_init(&drbg->drbg_mutex);
1824 
1825         return 0;
1826 }
1827 
1828 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1829 {
1830         drbg_uninstantiate(crypto_tfm_ctx(tfm));
1831 }
1832 
1833 /*
1834  * Generate random numbers invoked by the kernel crypto API:
1835  * The API of the kernel crypto API is extended as follows:
1836  *
1837  * src is additional input supplied to the RNG.
1838  * slen is the length of src.
1839  * dst is the output buffer where random data is to be stored.
1840  * dlen is the length of dst.
1841  */
1842 static int drbg_kcapi_random(struct crypto_rng *tfm,
1843                              const u8 *src, unsigned int slen,
1844                              u8 *dst, unsigned int dlen)
1845 {
1846         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1847         struct drbg_string *addtl = NULL;
1848         struct drbg_string string;
1849 
1850         if (slen) {
1851                 /* linked list variable is now local to allow modification */
1852                 drbg_string_fill(&string, src, slen);
1853                 addtl = &string;
1854         }
1855 
1856         return drbg_generate_long(drbg, dst, dlen, addtl);
1857 }
1858 
1859 /*
1860  * Seed the DRBG invoked by the kernel crypto API
1861  */
1862 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1863                            const u8 *seed, unsigned int slen)
1864 {
1865         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1866         struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1867         bool pr = false;
1868         struct drbg_string string;
1869         struct drbg_string *seed_string = NULL;
1870         int coreref = 0;
1871 
1872         drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1873                               &pr);
1874         if (0 < slen) {
1875                 drbg_string_fill(&string, seed, slen);
1876                 seed_string = &string;
1877         }
1878 
1879         return drbg_instantiate(drbg, seed_string, coreref, pr);
1880 }
1881 
1882 /***************************************************************
1883  * Kernel module: code to load the module
1884  ***************************************************************/
1885 
1886 /*
1887  * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1888  * of the error handling.
1889  *
1890  * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1891  * as seed source of get_random_bytes does not fail.
1892  *
1893  * Note 2: There is no sensible way of testing the reseed counter
1894  * enforcement, so skip it.
1895  */
1896 static inline int __init drbg_healthcheck_sanity(void)
1897 {
1898         int len = 0;
1899 #define OUTBUFLEN 16
1900         unsigned char buf[OUTBUFLEN];
1901         struct drbg_state *drbg = NULL;
1902         int ret = -EFAULT;
1903         int rc = -EFAULT;
1904         bool pr = false;
1905         int coreref = 0;
1906         struct drbg_string addtl;
1907         size_t max_addtllen, max_request_bytes;
1908 
1909         /* only perform test in FIPS mode */
1910         if (!fips_enabled)
1911                 return 0;
1912 
1913 #ifdef CONFIG_CRYPTO_DRBG_CTR
1914         drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1915 #elif defined CONFIG_CRYPTO_DRBG_HASH
1916         drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1917 #else
1918         drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1919 #endif
1920 
1921         drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1922         if (!drbg)
1923                 return -ENOMEM;
1924 
1925         mutex_init(&drbg->drbg_mutex);
1926         drbg->core = &drbg_cores[coreref];
1927         drbg->reseed_threshold = drbg_max_requests(drbg);
1928 
1929         /*
1930          * if the following tests fail, it is likely that there is a buffer
1931          * overflow as buf is much smaller than the requested or provided
1932          * string lengths -- in case the error handling does not succeed
1933          * we may get an OOPS. And we want to get an OOPS as this is a
1934          * grave bug.
1935          */
1936 
1937         max_addtllen = drbg_max_addtl(drbg);
1938         max_request_bytes = drbg_max_request_bytes(drbg);
1939         drbg_string_fill(&addtl, buf, max_addtllen + 1);
1940         /* overflow addtllen with additonal info string */
1941         len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1942         BUG_ON(0 < len);
1943         /* overflow max_bits */
1944         len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1945         BUG_ON(0 < len);
1946 
1947         /* overflow max addtllen with personalization string */
1948         ret = drbg_seed(drbg, &addtl, false);
1949         BUG_ON(0 == ret);
1950         /* all tests passed */
1951         rc = 0;
1952 
1953         pr_devel("DRBG: Sanity tests for failure code paths successfully "
1954                  "completed\n");
1955 
1956         kfree(drbg);
1957         return rc;
1958 }
1959 
1960 static struct rng_alg drbg_algs[22];
1961 
1962 /*
1963  * Fill the array drbg_algs used to register the different DRBGs
1964  * with the kernel crypto API. To fill the array, the information
1965  * from drbg_cores[] is used.
1966  */
1967 static inline void __init drbg_fill_array(struct rng_alg *alg,
1968                                           const struct drbg_core *core, int pr)
1969 {
1970         int pos = 0;
1971         static int priority = 200;
1972 
1973         memcpy(alg->base.cra_name, "stdrng", 6);
1974         if (pr) {
1975                 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1976                 pos = 8;
1977         } else {
1978                 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1979                 pos = 10;
1980         }
1981         memcpy(alg->base.cra_driver_name + pos, core->cra_name,
1982                strlen(core->cra_name));
1983 
1984         alg->base.cra_priority = priority;
1985         priority++;
1986         /*
1987          * If FIPS mode enabled, the selected DRBG shall have the
1988          * highest cra_priority over other stdrng instances to ensure
1989          * it is selected.
1990          */
1991         if (fips_enabled)
1992                 alg->base.cra_priority += 200;
1993 
1994         alg->base.cra_ctxsize   = sizeof(struct drbg_state);
1995         alg->base.cra_module    = THIS_MODULE;
1996         alg->base.cra_init      = drbg_kcapi_init;
1997         alg->base.cra_exit      = drbg_kcapi_cleanup;
1998         alg->generate           = drbg_kcapi_random;
1999         alg->seed               = drbg_kcapi_seed;
2000         alg->set_ent            = drbg_kcapi_set_entropy;
2001         alg->seedsize           = 0;
2002 }
2003 
2004 static int __init drbg_init(void)
2005 {
2006         unsigned int i = 0; /* pointer to drbg_algs */
2007         unsigned int j = 0; /* pointer to drbg_cores */
2008         int ret;
2009 
2010         ret = drbg_healthcheck_sanity();
2011         if (ret)
2012                 return ret;
2013 
2014         if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2015                 pr_info("DRBG: Cannot register all DRBG types"
2016                         "(slots needed: %zu, slots available: %zu)\n",
2017                         ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2018                 return -EFAULT;
2019         }
2020 
2021         /*
2022          * each DRBG definition can be used with PR and without PR, thus
2023          * we instantiate each DRBG in drbg_cores[] twice.
2024          *
2025          * As the order of placing them into the drbg_algs array matters
2026          * (the later DRBGs receive a higher cra_priority) we register the
2027          * prediction resistance DRBGs first as the should not be too
2028          * interesting.
2029          */
2030         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2031                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2032         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2033                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2034         return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2035 }
2036 
2037 static void __exit drbg_exit(void)
2038 {
2039         crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2040 }
2041 
2042 module_init(drbg_init);
2043 module_exit(drbg_exit);
2044 #ifndef CRYPTO_DRBG_HASH_STRING
2045 #define CRYPTO_DRBG_HASH_STRING ""
2046 #endif
2047 #ifndef CRYPTO_DRBG_HMAC_STRING
2048 #define CRYPTO_DRBG_HMAC_STRING ""
2049 #endif
2050 #ifndef CRYPTO_DRBG_CTR_STRING
2051 #define CRYPTO_DRBG_CTR_STRING ""
2052 #endif
2053 MODULE_LICENSE("GPL");
2054 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2055 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2056                    "using following cores: "
2057                    CRYPTO_DRBG_HASH_STRING
2058                    CRYPTO_DRBG_HMAC_STRING
2059                    CRYPTO_DRBG_CTR_STRING);
2060 MODULE_ALIAS_CRYPTO("stdrng");
2061 

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