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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
32
33
34#define PRNG_FIXED_SIZE 0x1
35#define PRNG_NEED_RESET 0x2
36
37
38
39
40
41
42
43
44
45
46struct 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
58static int dbg;
59
60static 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 {\
71if (dbg)\
72 printk(format, ##args);\
73} while (0)
74
75static 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
86
87
88static 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
104
105 for (i = 0; i < 3; i++) {
106
107 switch (i) {
108 case 0:
109
110
111
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
121
122
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
131
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
152
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
163 crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
164
165 }
166
167
168
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
188static 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
204
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
219remainder:
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
230
231 if (byte_count < DEFAULT_BLK_SZ) {
232empty_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
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
263
264 if (byte_count)
265 goto remainder;
266
267done:
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
274static void free_prng_context(struct prng_context *ctx)
275{
276 crypto_free_cipher(ctx->tfm);
277}
278
279static 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;
318out:
319 spin_unlock_bh(&ctx->prng_lock);
320 return ret;
321}
322
323static 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
340
341
342
343 ctx->flags |= PRNG_NEED_RESET;
344 return 0;
345}
346
347static void cprng_exit(struct crypto_tfm *tfm)
348{
349 free_prng_context(crypto_tfm_ctx(tfm));
350}
351
352static 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
362
363
364
365
366static 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
385static struct crypto_alg rng_alg = {
386 .cra_name = "stdrng",
387 .cra_driver_name = "ansi_cprng",
388 .cra_priority = 100,
389 .cra_flags = CRYPTO_ALG_TYPE_RNG,
390 .cra_ctxsize = sizeof(struct prng_context),
391 .cra_type = &crypto_rng_type,
392 .cra_module = THIS_MODULE,
393 .cra_list = LIST_HEAD_INIT(rng_alg.cra_list),
394 .cra_init = cprng_init,
395 .cra_exit = cprng_exit,
396 .cra_u = {
397 .rng = {
398 .rng_make_random = cprng_get_random,
399 .rng_reset = cprng_reset,
400 .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ,
401 }
402 }
403};
404
405#ifdef CONFIG_CRYPTO_FIPS
406static int fips_cprng_get_random(struct crypto_rng *tfm, u8 *rdata,
407 unsigned int dlen)
408{
409 struct prng_context *prng = crypto_rng_ctx(tfm);
410
411 return get_prng_bytes(rdata, dlen, prng, 1);
412}
413
414static int fips_cprng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
415{
416 u8 rdata[DEFAULT_BLK_SZ];
417 int rc;
418
419 struct prng_context *prng = crypto_rng_ctx(tfm);
420
421 rc = cprng_reset(tfm, seed, slen);
422
423 if (!rc)
424 goto out;
425
426
427 rc = get_prng_bytes(rdata, DEFAULT_BLK_SZ, prng, 0);
428 prng->rand_data_valid = DEFAULT_BLK_SZ;
429
430out:
431 return rc;
432}
433
434static struct crypto_alg fips_rng_alg = {
435 .cra_name = "fips(ansi_cprng)",
436 .cra_driver_name = "fips_ansi_cprng",
437 .cra_priority = 300,
438 .cra_flags = CRYPTO_ALG_TYPE_RNG,
439 .cra_ctxsize = sizeof(struct prng_context),
440 .cra_type = &crypto_rng_type,
441 .cra_module = THIS_MODULE,
442 .cra_list = LIST_HEAD_INIT(rng_alg.cra_list),
443 .cra_init = cprng_init,
444 .cra_exit = cprng_exit,
445 .cra_u = {
446 .rng = {
447 .rng_make_random = fips_cprng_get_random,
448 .rng_reset = fips_cprng_reset,
449 .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ,
450 }
451 }
452};
453#endif
454
455
456static int __init prng_mod_init(void)
457{
458 int rc = 0;
459
460 rc = crypto_register_alg(&rng_alg);
461#ifdef CONFIG_CRYPTO_FIPS
462 if (rc)
463 goto out;
464
465 rc = crypto_register_alg(&fips_rng_alg);
466
467out:
468#endif
469 return rc;
470}
471
472static void __exit prng_mod_fini(void)
473{
474 crypto_unregister_alg(&rng_alg);
475#ifdef CONFIG_CRYPTO_FIPS
476 crypto_unregister_alg(&fips_rng_alg);
477#endif
478 return;
479}
480
481MODULE_LICENSE("GPL");
482MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
483MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
484module_param(dbg, int, 0);
485MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
486module_init(prng_mod_init);
487module_exit(prng_mod_fini);
488MODULE_ALIAS("stdrng");
489
