~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/crypto/ansi_cprng.c

Version: ~ [ linux-5.5-rc1 ] ~ [ linux-5.4.2 ] ~ [ linux-5.3.15 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.88 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.158 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.206 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.206 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.78 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  * PRNG: Pseudo Random Number Generator
  3  *       Based on NIST Recommended PRNG From ANSI X9.31 Appendix A.2.4 using
  4  *       AES 128 cipher
  5  *
  6  *  (C) Neil Horman <nhorman@tuxdriver.com>
  7  *
  8  *  This program is free software; you can redistribute it and/or modify it
  9  *  under the terms of the GNU General Public License as published by the
 10  *  Free Software Foundation; either version 2 of the License, or (at your
 11  *  any later version.
 12  *
 13  *
 14  */
 15 
 16 #include <crypto/internal/rng.h>
 17 #include <linux/err.h>
 18 #include <linux/init.h>
 19 #include <linux/module.h>
 20 #include <linux/moduleparam.h>
 21 #include <linux/string.h>
 22 
 23 #include "internal.h"
 24 
 25 #define DEFAULT_PRNG_KEY "0123456789abcdef"
 26 #define DEFAULT_PRNG_KSZ 16
 27 #define DEFAULT_BLK_SZ 16
 28 #define DEFAULT_V_SEED "zaybxcwdveuftgsh"
 29 
 30 /*
 31  * Flags for the prng_context flags field
 32  */
 33 
 34 #define PRNG_FIXED_SIZE 0x1
 35 #define PRNG_NEED_RESET 0x2
 36 
 37 /*
 38  * Note: DT is our counter value
 39  *       I is our intermediate value
 40  *       V is our seed vector
 41  * See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
 42  * for implementation details
 43  */
 44 
 45 
 46 struct prng_context {
 47         spinlock_t prng_lock;
 48         unsigned char rand_data[DEFAULT_BLK_SZ];
 49         unsigned char last_rand_data[DEFAULT_BLK_SZ];
 50         unsigned char DT[DEFAULT_BLK_SZ];
 51         unsigned char I[DEFAULT_BLK_SZ];
 52         unsigned char V[DEFAULT_BLK_SZ];
 53         u32 rand_data_valid;
 54         struct crypto_cipher *tfm;
 55         u32 flags;
 56 };
 57 
 58 static int dbg;
 59 
 60 static void hexdump(char *note, unsigned char *buf, unsigned int len)
 61 {
 62         if (dbg) {
 63                 printk(KERN_CRIT "%s", note);
 64                 print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
 65                                 16, 1,
 66                                 buf, len, false);
 67         }
 68 }
 69 
 70 #define dbgprint(format, args...) do {\
 71 if (dbg)\
 72         printk(format, ##args);\
 73 } while (0)
 74 
 75 static void xor_vectors(unsigned char *in1, unsigned char *in2,
 76                         unsigned char *out, unsigned int size)
 77 {
 78         int i;
 79 
 80         for (i = 0; i < size; i++)
 81                 out[i] = in1[i] ^ in2[i];
 82 
 83 }
 84 /*
 85  * Returns DEFAULT_BLK_SZ bytes of random data per call
 86  * returns 0 if generation succeeded, <0 if something went wrong
 87  */
 88 static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
 89 {
 90         int i;
 91         unsigned char tmp[DEFAULT_BLK_SZ];
 92         unsigned char *output = NULL;
 93 
 94 
 95         dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
 96                 ctx);
 97 
 98         hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
 99         hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
100         hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
101 
102         /*
103          * This algorithm is a 3 stage state machine
104          */
105         for (i = 0; i < 3; i++) {
106 
107                 switch (i) {
108                 case 0:
109                         /*
110                          * Start by encrypting the counter value
111                          * This gives us an intermediate value I
112                          */
113                         memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
114                         output = ctx->I;
115                         hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
116                         break;
117                 case 1:
118 
119                         /*
120                          * Next xor I with our secret vector V
121                          * encrypt that result to obtain our
122                          * pseudo random data which we output
123                          */
124                         xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
125                         hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
126                         output = ctx->rand_data;
127                         break;
128                 case 2:
129                         /*
130                          * First check that we didn't produce the same
131                          * random data that we did last time around through this
132                          */
133                         if (!memcmp(ctx->rand_data, ctx->last_rand_data,
134                                         DEFAULT_BLK_SZ)) {
135                                 if (cont_test) {
136                                         panic("cprng %p Failed repetition check!\n",
137                                                 ctx);
138                                 }
139 
140                                 printk(KERN_ERR
141                                         "ctx %p Failed repetition check!\n",
142                                         ctx);
143 
144                                 ctx->flags |= PRNG_NEED_RESET;
145                                 return -EINVAL;
146                         }
147                         memcpy(ctx->last_rand_data, ctx->rand_data,
148                                 DEFAULT_BLK_SZ);
149 
150                         /*
151                          * Lastly xor the random data with I
152                          * and encrypt that to obtain a new secret vector V
153                          */
154                         xor_vectors(ctx->rand_data, ctx->I, tmp,
155                                 DEFAULT_BLK_SZ);
156                         output = ctx->V;
157                         hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
158                         break;
159                 }
160 
161 
162                 /* do the encryption */
163                 crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
164 
165         }
166 
167         /*
168          * Now update our DT value
169          */
170         for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
171                 ctx->DT[i] += 1;
172                 if (ctx->DT[i] != 0)
173                         break;
174         }
175 
176         dbgprint("Returning new block for context %p\n", ctx);
177         ctx->rand_data_valid = 0;
178 
179         hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
180         hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
181         hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
182         hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
183 
184         return 0;
185 }
186 
187 /* Our exported functions */
188 static int get_prng_bytes(char *buf, size_t nbytes, struct prng_context *ctx,
189                                 int do_cont_test)
190 {
191         unsigned char *ptr = buf;
192         unsigned int byte_count = (unsigned int)nbytes;
193         int err;
194 
195 
196         spin_lock_bh(&ctx->prng_lock);
197 
198         err = -EINVAL;
199         if (ctx->flags & PRNG_NEED_RESET)
200                 goto done;
201 
202         /*
203          * If the FIXED_SIZE flag is on, only return whole blocks of
204          * pseudo random data
205          */
206         err = -EINVAL;
207         if (ctx->flags & PRNG_FIXED_SIZE) {
208                 if (nbytes < DEFAULT_BLK_SZ)
209                         goto done;
210                 byte_count = DEFAULT_BLK_SZ;
211         }
212 
213         err = byte_count;
214 
215         dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",
216                 byte_count, ctx);
217 
218 
219 remainder:
220         if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
221                 if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
222                         memset(buf, 0, nbytes);
223                         err = -EINVAL;
224                         goto done;
225                 }
226         }
227 
228         /*
229          * Copy any data less than an entire block
230          */
231         if (byte_count < DEFAULT_BLK_SZ) {
232 empty_rbuf:
233                 for (; ctx->rand_data_valid < DEFAULT_BLK_SZ;
234                         ctx->rand_data_valid++) {
235                         *ptr = ctx->rand_data[ctx->rand_data_valid];
236                         ptr++;
237                         byte_count--;
238                         if (byte_count == 0)
239                                 goto done;
240                 }
241         }
242 
243         /*
244          * Now copy whole blocks
245          */
246         for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
247                 if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
248                         if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
249                                 memset(buf, 0, nbytes);
250                                 err = -EINVAL;
251                                 goto done;
252                         }
253                 }
254                 if (ctx->rand_data_valid > 0)
255                         goto empty_rbuf;
256                 memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
257                 ctx->rand_data_valid += DEFAULT_BLK_SZ;
258                 ptr += DEFAULT_BLK_SZ;
259         }
260 
261         /*
262          * Now go back and get any remaining partial block
263          */
264         if (byte_count)
265                 goto remainder;
266 
267 done:
268         spin_unlock_bh(&ctx->prng_lock);
269         dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
270                 err, ctx);
271         return err;
272 }
273 
274 static void free_prng_context(struct prng_context *ctx)
275 {
276         crypto_free_cipher(ctx->tfm);
277 }
278 
279 static int reset_prng_context(struct prng_context *ctx,
280                               unsigned char *key, size_t klen,
281                               unsigned char *V, unsigned char *DT)
282 {
283         int ret;
284         unsigned char *prng_key;
285 
286         spin_lock_bh(&ctx->prng_lock);
287         ctx->flags |= PRNG_NEED_RESET;
288 
289         prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;
290 
291         if (!key)
292                 klen = DEFAULT_PRNG_KSZ;
293 
294         if (V)
295                 memcpy(ctx->V, V, DEFAULT_BLK_SZ);
296         else
297                 memcpy(ctx->V, DEFAULT_V_SEED, DEFAULT_BLK_SZ);
298 
299         if (DT)
300                 memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
301         else
302                 memset(ctx->DT, 0, DEFAULT_BLK_SZ);
303 
304         memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
305         memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);
306 
307         ctx->rand_data_valid = DEFAULT_BLK_SZ;
308 
309         ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
310         if (ret) {
311                 dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
312                         crypto_cipher_get_flags(ctx->tfm));
313                 goto out;
314         }
315 
316         ret = 0;
317         ctx->flags &= ~PRNG_NEED_RESET;
318 out:
319         spin_unlock_bh(&ctx->prng_lock);
320         return ret;
321 }
322 
323 static int cprng_init(struct crypto_tfm *tfm)
324 {
325         struct prng_context *ctx = crypto_tfm_ctx(tfm);
326 
327         spin_lock_init(&ctx->prng_lock);
328         ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
329         if (IS_ERR(ctx->tfm)) {
330                 dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
331                                 ctx);
332                 return PTR_ERR(ctx->tfm);
333         }
334 
335         if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
336                 return -EINVAL;
337 
338         /*
339          * after allocation, we should always force the user to reset
340          * so they don't inadvertently use the insecure default values
341          * without specifying them intentially
342          */
343         ctx->flags |= PRNG_NEED_RESET;
344         return 0;
345 }
346 
347 static void cprng_exit(struct crypto_tfm *tfm)
348 {
349         free_prng_context(crypto_tfm_ctx(tfm));
350 }
351 
352 static int cprng_get_random(struct crypto_rng *tfm, u8 *rdata,
353                             unsigned int dlen)
354 {
355         struct prng_context *prng = crypto_rng_ctx(tfm);
356 
357         return get_prng_bytes(rdata, dlen, prng, 0);
358 }
359 
360 /*
361  *  This is the cprng_registered reset method the seed value is
362  *  interpreted as the tuple { V KEY DT}
363  *  V and KEY are required during reset, and DT is optional, detected
364  *  as being present by testing the length of the seed
365  */
366 static int cprng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
367 {
368         struct prng_context *prng = crypto_rng_ctx(tfm);
369         u8 *key = seed + DEFAULT_BLK_SZ;
370         u8 *dt = NULL;
371 
372         if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
373                 return -EINVAL;
374 
375         if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ))
376                 dt = key + DEFAULT_PRNG_KSZ;
377 
378         reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt);
379 
380         if (prng->flags & PRNG_NEED_RESET)
381                 return -EINVAL;
382         return 0;
383 }
384 
385 #ifdef CONFIG_CRYPTO_FIPS
386 static int fips_cprng_get_random(struct crypto_rng *tfm, u8 *rdata,
387                             unsigned int dlen)
388 {
389         struct prng_context *prng = crypto_rng_ctx(tfm);
390 
391         return get_prng_bytes(rdata, dlen, prng, 1);
392 }
393 
394 static int fips_cprng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
395 {
396         u8 rdata[DEFAULT_BLK_SZ];
397         u8 *key = seed + DEFAULT_BLK_SZ;
398         int rc;
399 
400         struct prng_context *prng = crypto_rng_ctx(tfm);
401 
402         if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
403                 return -EINVAL;
404 
405         /* fips strictly requires seed != key */
406         if (!memcmp(seed, key, DEFAULT_PRNG_KSZ))
407                 return -EINVAL;
408 
409         rc = cprng_reset(tfm, seed, slen);
410 
411         if (!rc)
412                 goto out;
413 
414         /* this primes our continuity test */
415         rc = get_prng_bytes(rdata, DEFAULT_BLK_SZ, prng, 0);
416         prng->rand_data_valid = DEFAULT_BLK_SZ;
417 
418 out:
419         return rc;
420 }
421 #endif
422 
423 static struct crypto_alg rng_algs[] = { {
424         .cra_name               = "stdrng",
425         .cra_driver_name        = "ansi_cprng",
426         .cra_priority           = 100,
427         .cra_flags              = CRYPTO_ALG_TYPE_RNG,
428         .cra_ctxsize            = sizeof(struct prng_context),
429         .cra_type               = &crypto_rng_type,
430         .cra_module             = THIS_MODULE,
431         .cra_init               = cprng_init,
432         .cra_exit               = cprng_exit,
433         .cra_u                  = {
434                 .rng = {
435                         .rng_make_random        = cprng_get_random,
436                         .rng_reset              = cprng_reset,
437                         .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ,
438                 }
439         }
440 #ifdef CONFIG_CRYPTO_FIPS
441 }, {
442         .cra_name               = "fips(ansi_cprng)",
443         .cra_driver_name        = "fips_ansi_cprng",
444         .cra_priority           = 300,
445         .cra_flags              = CRYPTO_ALG_TYPE_RNG,
446         .cra_ctxsize            = sizeof(struct prng_context),
447         .cra_type               = &crypto_rng_type,
448         .cra_module             = THIS_MODULE,
449         .cra_init               = cprng_init,
450         .cra_exit               = cprng_exit,
451         .cra_u                  = {
452                 .rng = {
453                         .rng_make_random        = fips_cprng_get_random,
454                         .rng_reset              = fips_cprng_reset,
455                         .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ,
456                 }
457         }
458 #endif
459 } };
460 
461 /* Module initalization */
462 static int __init prng_mod_init(void)
463 {
464         return crypto_register_algs(rng_algs, ARRAY_SIZE(rng_algs));
465 }
466 
467 static void __exit prng_mod_fini(void)
468 {
469         crypto_unregister_algs(rng_algs, ARRAY_SIZE(rng_algs));
470 }
471 
472 MODULE_LICENSE("GPL");
473 MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
474 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
475 module_param(dbg, int, 0);
476 MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
477 module_init(prng_mod_init);
478 module_exit(prng_mod_fini);
479 MODULE_ALIAS("stdrng");
480 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp