summaryrefslogtreecommitdiffstats
path: root/arch/s390/crypto/prng.c
blob: 1113389d0a39fe661229b68d28cf99e7a2e18eab (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
/*
 * Copyright IBM Corp. 2006, 2015
 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
 *	      Harald Freudenberger <freude@de.ibm.com>
 * Driver for the s390 pseudo random number generator
 */

#define KMSG_COMPONENT "prng"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/fs.h>
#include <linux/fips.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/cpufeature.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <asm/debug.h>
#include <asm/uaccess.h>
#include <asm/timex.h>
#include <asm/cpacf.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("IBM Corporation");
MODULE_DESCRIPTION("s390 PRNG interface");


#define PRNG_MODE_AUTO	  0
#define PRNG_MODE_TDES	  1
#define PRNG_MODE_SHA512  2

static unsigned int prng_mode = PRNG_MODE_AUTO;
module_param_named(mode, prng_mode, int, 0);
MODULE_PARM_DESC(prng_mode, "PRNG mode: 0 - auto, 1 - TDES, 2 - SHA512");


#define PRNG_CHUNKSIZE_TDES_MIN   8
#define PRNG_CHUNKSIZE_TDES_MAX   (64*1024)
#define PRNG_CHUNKSIZE_SHA512_MIN 64
#define PRNG_CHUNKSIZE_SHA512_MAX (64*1024)

static unsigned int prng_chunk_size = 256;
module_param_named(chunksize, prng_chunk_size, int, 0);
MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes");


#define PRNG_RESEED_LIMIT_TDES		 4096
#define PRNG_RESEED_LIMIT_TDES_LOWER	 4096
#define PRNG_RESEED_LIMIT_SHA512       100000
#define PRNG_RESEED_LIMIT_SHA512_LOWER	10000

static unsigned int prng_reseed_limit;
module_param_named(reseed_limit, prng_reseed_limit, int, 0);
MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit");


/*
 * Any one who considers arithmetical methods of producing random digits is,
 * of course, in a state of sin. -- John von Neumann
 */

static int prng_errorflag;

#define PRNG_GEN_ENTROPY_FAILED  1
#define PRNG_SELFTEST_FAILED	 2
#define PRNG_INSTANTIATE_FAILED  3
#define PRNG_SEED_FAILED	 4
#define PRNG_RESEED_FAILED	 5
#define PRNG_GEN_FAILED		 6

struct prng_ws_s {
	u8  parm_block[32];
	u32 reseed_counter;
	u64 byte_counter;
};

struct ppno_ws_s {
	u32 res;
	u32 reseed_counter;
	u64 stream_bytes;
	u8  V[112];
	u8  C[112];
};

struct prng_data_s {
	struct mutex mutex;
	union {
		struct prng_ws_s prngws;
		struct ppno_ws_s ppnows;
	};
	u8 *buf;
	u32 rest;
	u8 *prev;
};

static struct prng_data_s *prng_data;

/* initial parameter block for tdes mode, copied from libica */
static const u8 initial_parm_block[32] __initconst = {
	0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
	0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
	0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
	0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 };


/*** helper functions ***/

static int generate_entropy(u8 *ebuf, size_t nbytes)
{
	int n, ret = 0;
	u8 *pg, *h, hash[32];

	pg = (u8 *) __get_free_page(GFP_KERNEL);
	if (!pg) {
		prng_errorflag = PRNG_GEN_ENTROPY_FAILED;
		return -ENOMEM;
	}

	while (nbytes) {
		/* fill page with urandom bytes */
		get_random_bytes(pg, PAGE_SIZE);
		/* exor page with stckf values */
		for (n = 0; n < PAGE_SIZE / sizeof(u64); n++) {
			u64 *p = ((u64 *)pg) + n;
			*p ^= get_tod_clock_fast();
		}
		n = (nbytes < sizeof(hash)) ? nbytes : sizeof(hash);
		if (n < sizeof(hash))
			h = hash;
		else
			h = ebuf;
		/* generate sha256 from this page */
		cpacf_kimd(CPACF_KIMD_SHA_256, h, pg, PAGE_SIZE);
		if (n < sizeof(hash))
			memcpy(ebuf, hash, n);
		ret += n;
		ebuf += n;
		nbytes -= n;
	}

	free_page((unsigned long)pg);
	return ret;
}


/*** tdes functions ***/

static void prng_tdes_add_entropy(void)
{
	__u64 entropy[4];
	unsigned int i;

	for (i = 0; i < 16; i++) {
		cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
			  (char *) entropy, (char *) entropy,
			  sizeof(entropy));
		memcpy(prng_data->prngws.parm_block, entropy, sizeof(entropy));
	}
}


static void prng_tdes_seed(int nbytes)
{
	char buf[16];
	int i = 0;

	BUG_ON(nbytes > sizeof(buf));

	get_random_bytes(buf, nbytes);

	/* Add the entropy */
	while (nbytes >= 8) {
		*((__u64 *)prng_data->prngws.parm_block) ^= *((__u64 *)(buf+i));
		prng_tdes_add_entropy();
		i += 8;
		nbytes -= 8;
	}
	prng_tdes_add_entropy();
	prng_data->prngws.reseed_counter = 0;
}


static int __init prng_tdes_instantiate(void)
{
	int datalen;

	pr_debug("prng runs in TDES mode with "
		 "chunksize=%d and reseed_limit=%u\n",
		 prng_chunk_size, prng_reseed_limit);

	/* memory allocation, prng_data struct init, mutex init */
	datalen = sizeof(struct prng_data_s) + prng_chunk_size;
	prng_data = kzalloc(datalen, GFP_KERNEL);
	if (!prng_data) {
		prng_errorflag = PRNG_INSTANTIATE_FAILED;
		return -ENOMEM;
	}
	mutex_init(&prng_data->mutex);
	prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
	memcpy(prng_data->prngws.parm_block, initial_parm_block, 32);

	/* initialize the PRNG, add 128 bits of entropy */
	prng_tdes_seed(16);

	return 0;
}


static void prng_tdes_deinstantiate(void)
{
	pr_debug("The prng module stopped "
		 "after running in triple DES mode\n");
	kzfree(prng_data);
}


/*** sha512 functions ***/

static int __init prng_sha512_selftest(void)
{
	/* NIST DRBG testvector for Hash Drbg, Sha-512, Count #0 */
	static const u8 seed[] __initconst = {
		0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a,
		0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22,
		0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b,
		0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c,
		0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa,
		0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25 };
	static const u8 V0[] __initconst = {
		0x00, 0xad, 0xe3, 0x6f, 0x9a, 0x01, 0xc7, 0x76,
		0x61, 0x34, 0x35, 0xf5, 0x4e, 0x24, 0x74, 0x22,
		0x21, 0x9a, 0x29, 0x89, 0xc7, 0x93, 0x2e, 0x60,
		0x1e, 0xe8, 0x14, 0x24, 0x8d, 0xd5, 0x03, 0xf1,
		0x65, 0x5d, 0x08, 0x22, 0x72, 0xd5, 0xad, 0x95,
		0xe1, 0x23, 0x1e, 0x8a, 0xa7, 0x13, 0xd9, 0x2b,
		0x5e, 0xbc, 0xbb, 0x80, 0xab, 0x8d, 0xe5, 0x79,
		0xab, 0x5b, 0x47, 0x4e, 0xdd, 0xee, 0x6b, 0x03,
		0x8f, 0x0f, 0x5c, 0x5e, 0xa9, 0x1a, 0x83, 0xdd,
		0xd3, 0x88, 0xb2, 0x75, 0x4b, 0xce, 0x83, 0x36,
		0x57, 0x4b, 0xf1, 0x5c, 0xca, 0x7e, 0x09, 0xc0,
		0xd3, 0x89, 0xc6, 0xe0, 0xda, 0xc4, 0x81, 0x7e,
		0x5b, 0xf9, 0xe1, 0x01, 0xc1, 0x92, 0x05, 0xea,
		0xf5, 0x2f, 0xc6, 0xc6, 0xc7, 0x8f, 0xbc, 0xf4 };
	static const u8 C0[] __initconst = {
		0x00, 0xf4, 0xa3, 0xe5, 0xa0, 0x72, 0x63, 0x95,
		0xc6, 0x4f, 0x48, 0xd0, 0x8b, 0x5b, 0x5f, 0x8e,
		0x6b, 0x96, 0x1f, 0x16, 0xed, 0xbc, 0x66, 0x94,
		0x45, 0x31, 0xd7, 0x47, 0x73, 0x22, 0xa5, 0x86,
		0xce, 0xc0, 0x4c, 0xac, 0x63, 0xb8, 0x39, 0x50,
		0xbf, 0xe6, 0x59, 0x6c, 0x38, 0x58, 0x99, 0x1f,
		0x27, 0xa7, 0x9d, 0x71, 0x2a, 0xb3, 0x7b, 0xf9,
		0xfb, 0x17, 0x86, 0xaa, 0x99, 0x81, 0xaa, 0x43,
		0xe4, 0x37, 0xd3, 0x1e, 0x6e, 0xe5, 0xe6, 0xee,
		0xc2, 0xed, 0x95, 0x4f, 0x53, 0x0e, 0x46, 0x8a,
		0xcc, 0x45, 0xa5, 0xdb, 0x69, 0x0d, 0x81, 0xc9,
		0x32, 0x92, 0xbc, 0x8f, 0x33, 0xe6, 0xf6, 0x09,
		0x7c, 0x8e, 0x05, 0x19, 0x0d, 0xf1, 0xb6, 0xcc,
		0xf3, 0x02, 0x21, 0x90, 0x25, 0xec, 0xed, 0x0e };
	static const u8 random[] __initconst = {
		0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57,
		0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6,
		0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d,
		0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf,
		0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26,
		0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64,
		0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55,
		0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a,
		0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78,
		0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e,
		0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb,
		0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30,
		0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19,
		0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f,
		0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d,
		0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a,
		0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2,
		0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd,
		0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd,
		0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2,
		0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b,
		0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1,
		0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99,
		0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e,
		0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3,
		0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67,
		0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3,
		0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d,
		0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b,
		0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13,
		0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c,
		0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2 };

	u8 buf[sizeof(random)];
	struct ppno_ws_s ws;

	memset(&ws, 0, sizeof(ws));

	/* initial seed */
	cpacf_ppno(CPACF_PPNO_SHA512_DRNG_SEED,
		   &ws, NULL, 0, seed, sizeof(seed));

	/* check working states V and C */
	if (memcmp(ws.V, V0, sizeof(V0)) != 0
	    || memcmp(ws.C, C0, sizeof(C0)) != 0) {
		pr_err("The prng self test state test "
		       "for the SHA-512 mode failed\n");
		prng_errorflag = PRNG_SELFTEST_FAILED;
		return -EIO;
	}

	/* generate random bytes */
	cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
		   &ws, buf, sizeof(buf), NULL, 0);
	cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
		   &ws, buf, sizeof(buf), NULL, 0);

	/* check against expected data */
	if (memcmp(buf, random, sizeof(random)) != 0) {
		pr_err("The prng self test data test "
		       "for the SHA-512 mode failed\n");
		prng_errorflag = PRNG_SELFTEST_FAILED;
		return -EIO;
	}

	return 0;
}


static int __init prng_sha512_instantiate(void)
{
	int ret, datalen;
	u8 seed[64];

	pr_debug("prng runs in SHA-512 mode "
		 "with chunksize=%d and reseed_limit=%u\n",
		 prng_chunk_size, prng_reseed_limit);

	/* memory allocation, prng_data struct init, mutex init */
	datalen = sizeof(struct prng_data_s) + prng_chunk_size;
	if (fips_enabled)
		datalen += prng_chunk_size;
	prng_data = kzalloc(datalen, GFP_KERNEL);
	if (!prng_data) {
		prng_errorflag = PRNG_INSTANTIATE_FAILED;
		return -ENOMEM;
	}
	mutex_init(&prng_data->mutex);
	prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);

	/* selftest */
	ret = prng_sha512_selftest();
	if (ret)
		goto outfree;

	/* generate initial seed bytestring, first 48 bytes of entropy */
	ret = generate_entropy(seed, 48);
	if (ret != 48)
		goto outfree;
	/* followed by 16 bytes of unique nonce */
	get_tod_clock_ext(seed + 48);

	/* initial seed of the ppno drng */
	cpacf_ppno(CPACF_PPNO_SHA512_DRNG_SEED,
		   &prng_data->ppnows, NULL, 0, seed, sizeof(seed));

	/* if fips mode is enabled, generate a first block of random
	   bytes for the FIPS 140-2 Conditional Self Test */
	if (fips_enabled) {
		prng_data->prev = prng_data->buf + prng_chunk_size;
		cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
			   &prng_data->ppnows,
			   prng_data->prev, prng_chunk_size, NULL, 0);
	}

	return 0;

outfree:
	kfree(prng_data);
	return ret;
}


static void prng_sha512_deinstantiate(void)
{
	pr_debug("The prng module stopped after running in SHA-512 mode\n");
	kzfree(prng_data);
}


static int prng_sha512_reseed(void)
{
	int ret;
	u8 seed[32];

	/* generate 32 bytes of fresh entropy */
	ret = generate_entropy(seed, sizeof(seed));
	if (ret != sizeof(seed))
		return ret;

	/* do a reseed of the ppno drng with this bytestring */
	cpacf_ppno(CPACF_PPNO_SHA512_DRNG_SEED,
		   &prng_data->ppnows, NULL, 0, seed, sizeof(seed));

	return 0;
}


static int prng_sha512_generate(u8 *buf, size_t nbytes)
{
	int ret;

	/* reseed needed ? */
	if (prng_data->ppnows.reseed_counter > prng_reseed_limit) {
		ret = prng_sha512_reseed();
		if (ret)
			return ret;
	}

	/* PPNO generate */
	cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
		   &prng_data->ppnows, buf, nbytes, NULL, 0);

	/* FIPS 140-2 Conditional Self Test */
	if (fips_enabled) {
		if (!memcmp(prng_data->prev, buf, nbytes)) {
			prng_errorflag = PRNG_GEN_FAILED;
			return -EILSEQ;
		}
		memcpy(prng_data->prev, buf, nbytes);
	}

	return nbytes;
}


/*** file io functions ***/

static int prng_open(struct inode *inode, struct file *file)
{
	return nonseekable_open(inode, file);
}


static ssize_t prng_tdes_read(struct file *file, char __user *ubuf,
			      size_t nbytes, loff_t *ppos)
{
	int chunk, n, ret = 0;

	/* lock prng_data struct */
	if (mutex_lock_interruptible(&prng_data->mutex))
		return -ERESTARTSYS;

	while (nbytes) {
		if (need_resched()) {
			if (signal_pending(current)) {
				if (ret == 0)
					ret = -ERESTARTSYS;
				break;
			}
			/* give mutex free before calling schedule() */
			mutex_unlock(&prng_data->mutex);
			schedule();
			/* occopy mutex again */
			if (mutex_lock_interruptible(&prng_data->mutex)) {
				if (ret == 0)
					ret = -ERESTARTSYS;
				return ret;
			}
		}

		/*
		 * we lose some random bytes if an attacker issues
		 * reads < 8 bytes, but we don't care
		 */
		chunk = min_t(int, nbytes, prng_chunk_size);

		/* PRNG only likes multiples of 8 bytes */
		n = (chunk + 7) & -8;

		if (prng_data->prngws.reseed_counter > prng_reseed_limit)
			prng_tdes_seed(8);

		/* if the CPU supports PRNG stckf is present too */
		*((unsigned long long *)prng_data->buf) = get_tod_clock_fast();

		/*
		 * Beside the STCKF the input for the TDES-EDE is the output
		 * of the last operation. We differ here from X9.17 since we
		 * only store one timestamp into the buffer. Padding the whole
		 * buffer with timestamps does not improve security, since
		 * successive stckf have nearly constant offsets.
		 * If an attacker knows the first timestamp it would be
		 * trivial to guess the additional values. One timestamp
		 * is therefore enough and still guarantees unique input values.
		 *
		 * Note: you can still get strict X9.17 conformity by setting
		 * prng_chunk_size to 8 bytes.
		 */
		cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
			  prng_data->buf, prng_data->buf, n);

		prng_data->prngws.byte_counter += n;
		prng_data->prngws.reseed_counter += n;

		if (copy_to_user(ubuf, prng_data->buf, chunk)) {
			ret = -EFAULT;
			break;
		}

		nbytes -= chunk;
		ret += chunk;
		ubuf += chunk;
	}

	/* unlock prng_data struct */
	mutex_unlock(&prng_data->mutex);

	return ret;
}


static ssize_t prng_sha512_read(struct file *file, char __user *ubuf,
				size_t nbytes, loff_t *ppos)
{
	int n, ret = 0;
	u8 *p;

	/* if errorflag is set do nothing and return 'broken pipe' */
	if (prng_errorflag)
		return -EPIPE;

	/* lock prng_data struct */
	if (mutex_lock_interruptible(&prng_data->mutex))
		return -ERESTARTSYS;

	while (nbytes) {
		if (need_resched()) {
			if (signal_pending(current)) {
				if (ret == 0)
					ret = -ERESTARTSYS;
				break;
			}
			/* give mutex free before calling schedule() */
			mutex_unlock(&prng_data->mutex);
			schedule();
			/* occopy mutex again */
			if (mutex_lock_interruptible(&prng_data->mutex)) {
				if (ret == 0)
					ret = -ERESTARTSYS;
				return ret;
			}
		}
		if (prng_data->rest) {
			/* push left over random bytes from the previous read */
			p = prng_data->buf + prng_chunk_size - prng_data->rest;
			n = (nbytes < prng_data->rest) ?
				nbytes : prng_data->rest;
			prng_data->rest -= n;
		} else {
			/* generate one chunk of random bytes into read buf */
			p = prng_data->buf;
			n = prng_sha512_generate(p, prng_chunk_size);
			if (n < 0) {
				ret = n;
				break;
			}
			if (nbytes < prng_chunk_size) {
				n = nbytes;
				prng_data->rest = prng_chunk_size - n;
			} else {
				n = prng_chunk_size;
				prng_data->rest = 0;
			}
		}
		if (copy_to_user(ubuf, p, n)) {
			ret = -EFAULT;
			break;
		}
		ubuf += n;
		nbytes -= n;
		ret += n;
	}

	/* unlock prng_data struct */
	mutex_unlock(&prng_data->mutex);

	return ret;
}


/*** sysfs stuff ***/

static const struct file_operations prng_sha512_fops = {
	.owner		= THIS_MODULE,
	.open		= &prng_open,
	.release	= NULL,
	.read		= &prng_sha512_read,
	.llseek		= noop_llseek,
};
static const struct file_operations prng_tdes_fops = {
	.owner		= THIS_MODULE,
	.open		= &prng_open,
	.release	= NULL,
	.read		= &prng_tdes_read,
	.llseek		= noop_llseek,
};

static struct miscdevice prng_sha512_dev = {
	.name	= "prandom",
	.minor	= MISC_DYNAMIC_MINOR,
	.mode	= 0644,
	.fops	= &prng_sha512_fops,
};
static struct miscdevice prng_tdes_dev = {
	.name	= "prandom",
	.minor	= MISC_DYNAMIC_MINOR,
	.mode	= 0644,
	.fops	= &prng_tdes_fops,
};


/* chunksize attribute (ro) */
static ssize_t prng_chunksize_show(struct device *dev,
				   struct device_attribute *attr,
				   char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
}
static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);

/* counter attribute (ro) */
static ssize_t prng_counter_show(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{
	u64 counter;

	if (mutex_lock_interruptible(&prng_data->mutex))
		return -ERESTARTSYS;
	if (prng_mode == PRNG_MODE_SHA512)
		counter = prng_data->ppnows.stream_bytes;
	else
		counter = prng_data->prngws.byte_counter;
	mutex_unlock(&prng_data->mutex);

	return snprintf(buf, PAGE_SIZE, "%llu\n", counter);
}
static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);

/* errorflag attribute (ro) */
static ssize_t prng_errorflag_show(struct device *dev,
				   struct device_attribute *attr,
				   char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
}
static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);

/* mode attribute (ro) */
static ssize_t prng_mode_show(struct device *dev,
			      struct device_attribute *attr,
			      char *buf)
{
	if (prng_mode == PRNG_MODE_TDES)
		return snprintf(buf, PAGE_SIZE, "TDES\n");
	else
		return snprintf(buf, PAGE_SIZE, "SHA512\n");
}
static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);

/* reseed attribute (w) */
static ssize_t prng_reseed_store(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf, size_t count)
{
	if (mutex_lock_interruptible(&prng_data->mutex))
		return -ERESTARTSYS;
	prng_sha512_reseed();
	mutex_unlock(&prng_data->mutex);

	return count;
}
static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store);

/* reseed limit attribute (rw) */
static ssize_t prng_reseed_limit_show(struct device *dev,
				      struct device_attribute *attr,
				      char *buf)
{
	return snprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
}
static ssize_t prng_reseed_limit_store(struct device *dev,
				       struct device_attribute *attr,
				       const char *buf, size_t count)
{
	unsigned limit;

	if (sscanf(buf, "%u\n", &limit) != 1)
		return -EINVAL;

	if (prng_mode == PRNG_MODE_SHA512) {
		if (limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
			return -EINVAL;
	} else {
		if (limit < PRNG_RESEED_LIMIT_TDES_LOWER)
			return -EINVAL;
	}

	prng_reseed_limit = limit;

	return count;
}
static DEVICE_ATTR(reseed_limit, 0644,
		   prng_reseed_limit_show, prng_reseed_limit_store);

/* strength attribute (ro) */
static ssize_t prng_strength_show(struct device *dev,
				  struct device_attribute *attr,
				  char *buf)
{
	return snprintf(buf, PAGE_SIZE, "256\n");
}
static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);

static struct attribute *prng_sha512_dev_attrs[] = {
	&dev_attr_errorflag.attr,
	&dev_attr_chunksize.attr,
	&dev_attr_byte_counter.attr,
	&dev_attr_mode.attr,
	&dev_attr_reseed.attr,
	&dev_attr_reseed_limit.attr,
	&dev_attr_strength.attr,
	NULL
};
static struct attribute *prng_tdes_dev_attrs[] = {
	&dev_attr_chunksize.attr,
	&dev_attr_byte_counter.attr,
	&dev_attr_mode.attr,
	NULL
};

static struct attribute_group prng_sha512_dev_attr_group = {
	.attrs = prng_sha512_dev_attrs
};
static struct attribute_group prng_tdes_dev_attr_group = {
	.attrs = prng_tdes_dev_attrs
};


/*** module init and exit ***/

static int __init prng_init(void)
{
	int ret;

	/* check if the CPU has a PRNG */
	if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG))
		return -EOPNOTSUPP;

	/* choose prng mode */
	if (prng_mode != PRNG_MODE_TDES) {
		/* check for MSA5 support for PPNO operations */
		if (!cpacf_query_func(CPACF_PPNO, CPACF_PPNO_SHA512_DRNG_GEN)) {
			if (prng_mode == PRNG_MODE_SHA512) {
				pr_err("The prng module cannot "
				       "start in SHA-512 mode\n");
				return -EOPNOTSUPP;
			}
			prng_mode = PRNG_MODE_TDES;
		} else
			prng_mode = PRNG_MODE_SHA512;
	}

	if (prng_mode == PRNG_MODE_SHA512) {

		/* SHA512 mode */

		if (prng_chunk_size < PRNG_CHUNKSIZE_SHA512_MIN
		    || prng_chunk_size > PRNG_CHUNKSIZE_SHA512_MAX)
			return -EINVAL;
		prng_chunk_size = (prng_chunk_size + 0x3f) & ~0x3f;

		if (prng_reseed_limit == 0)
			prng_reseed_limit = PRNG_RESEED_LIMIT_SHA512;
		else if (prng_reseed_limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
			return -EINVAL;

		ret = prng_sha512_instantiate();
		if (ret)
			goto out;

		ret = misc_register(&prng_sha512_dev);
		if (ret) {
			prng_sha512_deinstantiate();
			goto out;
		}
		ret = sysfs_create_group(&prng_sha512_dev.this_device->kobj,
					 &prng_sha512_dev_attr_group);
		if (ret) {
			misc_deregister(&prng_sha512_dev);
			prng_sha512_deinstantiate();
			goto out;
		}

	} else {

		/* TDES mode */

		if (prng_chunk_size < PRNG_CHUNKSIZE_TDES_MIN
		    || prng_chunk_size > PRNG_CHUNKSIZE_TDES_MAX)
			return -EINVAL;
		prng_chunk_size = (prng_chunk_size + 0x07) & ~0x07;

		if (prng_reseed_limit == 0)
			prng_reseed_limit = PRNG_RESEED_LIMIT_TDES;
		else if (prng_reseed_limit < PRNG_RESEED_LIMIT_TDES_LOWER)
			return -EINVAL;

		ret = prng_tdes_instantiate();
		if (ret)
			goto out;

		ret = misc_register(&prng_tdes_dev);
		if (ret) {
			prng_tdes_deinstantiate();
			goto out;
		}
		ret = sysfs_create_group(&prng_tdes_dev.this_device->kobj,
					 &prng_tdes_dev_attr_group);
		if (ret) {
			misc_deregister(&prng_tdes_dev);
			prng_tdes_deinstantiate();
			goto out;
		}

	}

out:
	return ret;
}


static void __exit prng_exit(void)
{
	if (prng_mode == PRNG_MODE_SHA512) {
		sysfs_remove_group(&prng_sha512_dev.this_device->kobj,
				   &prng_sha512_dev_attr_group);
		misc_deregister(&prng_sha512_dev);
		prng_sha512_deinstantiate();
	} else {
		sysfs_remove_group(&prng_tdes_dev.this_device->kobj,
				   &prng_tdes_dev_attr_group);
		misc_deregister(&prng_tdes_dev);
		prng_tdes_deinstantiate();
	}
}

module_cpu_feature_match(MSA, prng_init);
module_exit(prng_exit);
OpenPOWER on IntegriCloud