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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright IBM Corp. 2006, 2015
4 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
5 * Harald Freudenberger <freude@de.ibm.com>
6 * Driver for the s390 pseudo random number generator
7 */
8
9#define KMSG_COMPONENT "prng"
10#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11
12#include <linux/fs.h>
13#include <linux/fips.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/device.h>
17#include <linux/miscdevice.h>
18#include <linux/module.h>
19#include <linux/moduleparam.h>
20#include <linux/mutex.h>
21#include <linux/cpufeature.h>
22#include <linux/random.h>
23#include <linux/slab.h>
24#include <linux/sched/signal.h>
25
26#include <asm/debug.h>
27#include <linux/uaccess.h>
28#include <asm/timex.h>
29#include <asm/cpacf.h>
30
31MODULE_LICENSE("GPL");
32MODULE_AUTHOR("IBM Corporation");
33MODULE_DESCRIPTION("s390 PRNG interface");
34
35
36#define PRNG_MODE_AUTO 0
37#define PRNG_MODE_TDES 1
38#define PRNG_MODE_SHA512 2
39
40static unsigned int prng_mode = PRNG_MODE_AUTO;
41module_param_named(mode, prng_mode, int, 0);
42MODULE_PARM_DESC(prng_mode, "PRNG mode: 0 - auto, 1 - TDES, 2 - SHA512");
43
44
45#define PRNG_CHUNKSIZE_TDES_MIN 8
46#define PRNG_CHUNKSIZE_TDES_MAX (64*1024)
47#define PRNG_CHUNKSIZE_SHA512_MIN 64
48#define PRNG_CHUNKSIZE_SHA512_MAX (64*1024)
49
50static unsigned int prng_chunk_size = 256;
51module_param_named(chunksize, prng_chunk_size, int, 0);
52MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes");
53
54
55#define PRNG_RESEED_LIMIT_TDES 4096
56#define PRNG_RESEED_LIMIT_TDES_LOWER 4096
57#define PRNG_RESEED_LIMIT_SHA512 100000
58#define PRNG_RESEED_LIMIT_SHA512_LOWER 10000
59
60static unsigned int prng_reseed_limit;
61module_param_named(reseed_limit, prng_reseed_limit, int, 0);
62MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit");
63
64static bool trng_available;
65
66/*
67 * Any one who considers arithmetical methods of producing random digits is,
68 * of course, in a state of sin. -- John von Neumann
69 */
70
71static int prng_errorflag;
72
73#define PRNG_GEN_ENTROPY_FAILED 1
74#define PRNG_SELFTEST_FAILED 2
75#define PRNG_INSTANTIATE_FAILED 3
76#define PRNG_SEED_FAILED 4
77#define PRNG_RESEED_FAILED 5
78#define PRNG_GEN_FAILED 6
79
80struct prng_ws_s {
81 u8 parm_block[32];
82 u32 reseed_counter;
83 u64 byte_counter;
84};
85
86struct prno_ws_s {
87 u32 res;
88 u32 reseed_counter;
89 u64 stream_bytes;
90 u8 V[112];
91 u8 C[112];
92};
93
94struct prng_data_s {
95 struct mutex mutex;
96 union {
97 struct prng_ws_s prngws;
98 struct prno_ws_s prnows;
99 };
100 u8 *buf;
101 u32 rest;
102 u8 *prev;
103};
104
105static struct prng_data_s *prng_data;
106
107/* initial parameter block for tdes mode, copied from libica */
108static const u8 initial_parm_block[32] __initconst = {
109 0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
110 0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
111 0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
112 0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 };
113
114
115/*** helper functions ***/
116
117/*
118 * generate_entropy:
119 * This function fills a given buffer with random bytes. The entropy within
120 * the random bytes given back is assumed to have at least 50% - meaning
121 * a 64 bytes buffer has at least 64 * 8 / 2 = 256 bits of entropy.
122 * Within the function the entropy generation is done in junks of 64 bytes.
123 * So the caller should also ask for buffer fill in multiples of 64 bytes.
124 * The generation of the entropy is based on the assumption that every stckf()
125 * invocation produces 0.5 bits of entropy. To accumulate 256 bits of entropy
126 * at least 512 stckf() values are needed. The entropy relevant part of the
127 * stckf value is bit 51 (counting starts at the left with bit nr 0) so
128 * here we use the lower 4 bytes and exor the values into 2k of bufferspace.
129 * To be on the save side, if there is ever a problem with stckf() the
130 * other half of the page buffer is filled with bytes from urandom via
131 * get_random_bytes(), so this function consumes 2k of urandom for each
132 * requested 64 bytes output data. Finally the buffer page is condensed into
133 * a 64 byte value by hashing with a SHA512 hash.
134 */
135static int generate_entropy(u8 *ebuf, size_t nbytes)
136{
137 int n, ret = 0;
138 u8 *pg, pblock[80] = {
139 /* 8 x 64 bit init values */
140 0x6A, 0x09, 0xE6, 0x67, 0xF3, 0xBC, 0xC9, 0x08,
141 0xBB, 0x67, 0xAE, 0x85, 0x84, 0xCA, 0xA7, 0x3B,
142 0x3C, 0x6E, 0xF3, 0x72, 0xFE, 0x94, 0xF8, 0x2B,
143 0xA5, 0x4F, 0xF5, 0x3A, 0x5F, 0x1D, 0x36, 0xF1,
144 0x51, 0x0E, 0x52, 0x7F, 0xAD, 0xE6, 0x82, 0xD1,
145 0x9B, 0x05, 0x68, 0x8C, 0x2B, 0x3E, 0x6C, 0x1F,
146 0x1F, 0x83, 0xD9, 0xAB, 0xFB, 0x41, 0xBD, 0x6B,
147 0x5B, 0xE0, 0xCD, 0x19, 0x13, 0x7E, 0x21, 0x79,
148 /* 128 bit counter total message bit length */
149 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
150 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00 };
151
152 /* allocate one page stckf buffer */
153 pg = (u8 *) __get_free_page(GFP_KERNEL);
154 if (!pg) {
155 prng_errorflag = PRNG_GEN_ENTROPY_FAILED;
156 return -ENOMEM;
157 }
158
159 /* fill the ebuf in chunks of 64 byte each */
160 while (nbytes) {
161 /* fill lower 2k with urandom bytes */
162 get_random_bytes(pg, PAGE_SIZE / 2);
163 /* exor upper 2k with 512 stckf values, offset 4 bytes each */
164 for (n = 0; n < 512; n++) {
165 int offset = (PAGE_SIZE / 2) + (n * 4) - 4;
166 u64 *p = (u64 *)(pg + offset);
167 *p ^= get_tod_clock_fast();
168 }
169 /* hash over the filled page */
170 cpacf_klmd(CPACF_KLMD_SHA_512, pblock, pg, PAGE_SIZE);
171 n = (nbytes < 64) ? nbytes : 64;
172 memcpy(ebuf, pblock, n);
173 ret += n;
174 ebuf += n;
175 nbytes -= n;
176 }
177
178 memzero_explicit(pblock, sizeof(pblock));
179 memzero_explicit(pg, PAGE_SIZE);
180 free_page((unsigned long)pg);
181 return ret;
182}
183
184
185/*** tdes functions ***/
186
187static void prng_tdes_add_entropy(void)
188{
189 __u64 entropy[4];
190 unsigned int i;
191
192 for (i = 0; i < 16; i++) {
193 cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
194 (char *) entropy, (char *) entropy,
195 sizeof(entropy));
196 memcpy(prng_data->prngws.parm_block, entropy, sizeof(entropy));
197 }
198}
199
200
201static void prng_tdes_seed(int nbytes)
202{
203 char buf[16];
204 int i = 0;
205
206 BUG_ON(nbytes > sizeof(buf));
207
208 get_random_bytes(buf, nbytes);
209
210 /* Add the entropy */
211 while (nbytes >= 8) {
212 *((__u64 *)prng_data->prngws.parm_block) ^= *((__u64 *)(buf+i));
213 prng_tdes_add_entropy();
214 i += 8;
215 nbytes -= 8;
216 }
217 prng_tdes_add_entropy();
218 prng_data->prngws.reseed_counter = 0;
219}
220
221
222static int __init prng_tdes_instantiate(void)
223{
224 int datalen;
225
226 pr_debug("prng runs in TDES mode with "
227 "chunksize=%d and reseed_limit=%u\n",
228 prng_chunk_size, prng_reseed_limit);
229
230 /* memory allocation, prng_data struct init, mutex init */
231 datalen = sizeof(struct prng_data_s) + prng_chunk_size;
232 prng_data = kzalloc(datalen, GFP_KERNEL);
233 if (!prng_data) {
234 prng_errorflag = PRNG_INSTANTIATE_FAILED;
235 return -ENOMEM;
236 }
237 mutex_init(&prng_data->mutex);
238 prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
239 memcpy(prng_data->prngws.parm_block, initial_parm_block, 32);
240
241 /* initialize the PRNG, add 128 bits of entropy */
242 prng_tdes_seed(16);
243
244 return 0;
245}
246
247
248static void prng_tdes_deinstantiate(void)
249{
250 pr_debug("The prng module stopped "
251 "after running in triple DES mode\n");
252 kzfree(prng_data);
253}
254
255
256/*** sha512 functions ***/
257
258static int __init prng_sha512_selftest(void)
259{
260 /* NIST DRBG testvector for Hash Drbg, Sha-512, Count #0 */
261 static const u8 seed[] __initconst = {
262 0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a,
263 0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22,
264 0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b,
265 0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c,
266 0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa,
267 0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25 };
268 static const u8 V0[] __initconst = {
269 0x00, 0xad, 0xe3, 0x6f, 0x9a, 0x01, 0xc7, 0x76,
270 0x61, 0x34, 0x35, 0xf5, 0x4e, 0x24, 0x74, 0x22,
271 0x21, 0x9a, 0x29, 0x89, 0xc7, 0x93, 0x2e, 0x60,
272 0x1e, 0xe8, 0x14, 0x24, 0x8d, 0xd5, 0x03, 0xf1,
273 0x65, 0x5d, 0x08, 0x22, 0x72, 0xd5, 0xad, 0x95,
274 0xe1, 0x23, 0x1e, 0x8a, 0xa7, 0x13, 0xd9, 0x2b,
275 0x5e, 0xbc, 0xbb, 0x80, 0xab, 0x8d, 0xe5, 0x79,
276 0xab, 0x5b, 0x47, 0x4e, 0xdd, 0xee, 0x6b, 0x03,
277 0x8f, 0x0f, 0x5c, 0x5e, 0xa9, 0x1a, 0x83, 0xdd,
278 0xd3, 0x88, 0xb2, 0x75, 0x4b, 0xce, 0x83, 0x36,
279 0x57, 0x4b, 0xf1, 0x5c, 0xca, 0x7e, 0x09, 0xc0,
280 0xd3, 0x89, 0xc6, 0xe0, 0xda, 0xc4, 0x81, 0x7e,
281 0x5b, 0xf9, 0xe1, 0x01, 0xc1, 0x92, 0x05, 0xea,
282 0xf5, 0x2f, 0xc6, 0xc6, 0xc7, 0x8f, 0xbc, 0xf4 };
283 static const u8 C0[] __initconst = {
284 0x00, 0xf4, 0xa3, 0xe5, 0xa0, 0x72, 0x63, 0x95,
285 0xc6, 0x4f, 0x48, 0xd0, 0x8b, 0x5b, 0x5f, 0x8e,
286 0x6b, 0x96, 0x1f, 0x16, 0xed, 0xbc, 0x66, 0x94,
287 0x45, 0x31, 0xd7, 0x47, 0x73, 0x22, 0xa5, 0x86,
288 0xce, 0xc0, 0x4c, 0xac, 0x63, 0xb8, 0x39, 0x50,
289 0xbf, 0xe6, 0x59, 0x6c, 0x38, 0x58, 0x99, 0x1f,
290 0x27, 0xa7, 0x9d, 0x71, 0x2a, 0xb3, 0x7b, 0xf9,
291 0xfb, 0x17, 0x86, 0xaa, 0x99, 0x81, 0xaa, 0x43,
292 0xe4, 0x37, 0xd3, 0x1e, 0x6e, 0xe5, 0xe6, 0xee,
293 0xc2, 0xed, 0x95, 0x4f, 0x53, 0x0e, 0x46, 0x8a,
294 0xcc, 0x45, 0xa5, 0xdb, 0x69, 0x0d, 0x81, 0xc9,
295 0x32, 0x92, 0xbc, 0x8f, 0x33, 0xe6, 0xf6, 0x09,
296 0x7c, 0x8e, 0x05, 0x19, 0x0d, 0xf1, 0xb6, 0xcc,
297 0xf3, 0x02, 0x21, 0x90, 0x25, 0xec, 0xed, 0x0e };
298 static const u8 random[] __initconst = {
299 0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57,
300 0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6,
301 0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d,
302 0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf,
303 0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26,
304 0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64,
305 0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55,
306 0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a,
307 0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78,
308 0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e,
309 0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb,
310 0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30,
311 0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19,
312 0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f,
313 0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d,
314 0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a,
315 0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2,
316 0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd,
317 0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd,
318 0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2,
319 0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b,
320 0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1,
321 0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99,
322 0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e,
323 0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3,
324 0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67,
325 0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3,
326 0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d,
327 0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b,
328 0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13,
329 0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c,
330 0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2 };
331
332 u8 buf[sizeof(random)];
333 struct prno_ws_s ws;
334
335 memset(&ws, 0, sizeof(ws));
336
337 /* initial seed */
338 cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
339 &ws, NULL, 0, seed, sizeof(seed));
340
341 /* check working states V and C */
342 if (memcmp(ws.V, V0, sizeof(V0)) != 0
343 || memcmp(ws.C, C0, sizeof(C0)) != 0) {
344 pr_err("The prng self test state test "
345 "for the SHA-512 mode failed\n");
346 prng_errorflag = PRNG_SELFTEST_FAILED;
347 return -EIO;
348 }
349
350 /* generate random bytes */
351 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
352 &ws, buf, sizeof(buf), NULL, 0);
353 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
354 &ws, buf, sizeof(buf), NULL, 0);
355
356 /* check against expected data */
357 if (memcmp(buf, random, sizeof(random)) != 0) {
358 pr_err("The prng self test data test "
359 "for the SHA-512 mode failed\n");
360 prng_errorflag = PRNG_SELFTEST_FAILED;
361 return -EIO;
362 }
363
364 return 0;
365}
366
367
368static int __init prng_sha512_instantiate(void)
369{
370 int ret, datalen, seedlen;
371 u8 seed[128 + 16];
372
373 pr_debug("prng runs in SHA-512 mode "
374 "with chunksize=%d and reseed_limit=%u\n",
375 prng_chunk_size, prng_reseed_limit);
376
377 /* memory allocation, prng_data struct init, mutex init */
378 datalen = sizeof(struct prng_data_s) + prng_chunk_size;
379 if (fips_enabled)
380 datalen += prng_chunk_size;
381 prng_data = kzalloc(datalen, GFP_KERNEL);
382 if (!prng_data) {
383 prng_errorflag = PRNG_INSTANTIATE_FAILED;
384 return -ENOMEM;
385 }
386 mutex_init(&prng_data->mutex);
387 prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
388
389 /* selftest */
390 ret = prng_sha512_selftest();
391 if (ret)
392 goto outfree;
393
394 /* generate initial seed, we need at least 256 + 128 bits entropy. */
395 if (trng_available) {
396 /*
397 * Trng available, so use it. The trng works in chunks of
398 * 32 bytes and produces 100% entropy. So we pull 64 bytes
399 * which gives us 512 bits entropy.
400 */
401 seedlen = 2 * 32;
402 cpacf_trng(NULL, 0, seed, seedlen);
403 } else {
404 /*
405 * No trng available, so use the generate_entropy() function.
406 * This function works in 64 byte junks and produces
407 * 50% entropy. So we pull 2*64 bytes which gives us 512 bits
408 * of entropy.
409 */
410 seedlen = 2 * 64;
411 ret = generate_entropy(seed, seedlen);
412 if (ret != seedlen)
413 goto outfree;
414 }
415
416 /* append the seed by 16 bytes of unique nonce */
417 get_tod_clock_ext(seed + seedlen);
418 seedlen += 16;
419
420 /* now initial seed of the prno drng */
421 cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
422 &prng_data->prnows, NULL, 0, seed, seedlen);
423 memzero_explicit(seed, sizeof(seed));
424
425 /* if fips mode is enabled, generate a first block of random
426 bytes for the FIPS 140-2 Conditional Self Test */
427 if (fips_enabled) {
428 prng_data->prev = prng_data->buf + prng_chunk_size;
429 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
430 &prng_data->prnows,
431 prng_data->prev, prng_chunk_size, NULL, 0);
432 }
433
434 return 0;
435
436outfree:
437 kfree(prng_data);
438 return ret;
439}
440
441
442static void prng_sha512_deinstantiate(void)
443{
444 pr_debug("The prng module stopped after running in SHA-512 mode\n");
445 kzfree(prng_data);
446}
447
448
449static int prng_sha512_reseed(void)
450{
451 int ret, seedlen;
452 u8 seed[64];
453
454 /* We need at least 256 bits of fresh entropy for reseeding */
455 if (trng_available) {
456 /* trng produces 256 bits entropy in 32 bytes */
457 seedlen = 32;
458 cpacf_trng(NULL, 0, seed, seedlen);
459 } else {
460 /* generate_entropy() produces 256 bits entropy in 64 bytes */
461 seedlen = 64;
462 ret = generate_entropy(seed, seedlen);
463 if (ret != sizeof(seed))
464 return ret;
465 }
466
467 /* do a reseed of the prno drng with this bytestring */
468 cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
469 &prng_data->prnows, NULL, 0, seed, seedlen);
470 memzero_explicit(seed, sizeof(seed));
471
472 return 0;
473}
474
475
476static int prng_sha512_generate(u8 *buf, size_t nbytes)
477{
478 int ret;
479
480 /* reseed needed ? */
481 if (prng_data->prnows.reseed_counter > prng_reseed_limit) {
482 ret = prng_sha512_reseed();
483 if (ret)
484 return ret;
485 }
486
487 /* PRNO generate */
488 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
489 &prng_data->prnows, buf, nbytes, NULL, 0);
490
491 /* FIPS 140-2 Conditional Self Test */
492 if (fips_enabled) {
493 if (!memcmp(prng_data->prev, buf, nbytes)) {
494 prng_errorflag = PRNG_GEN_FAILED;
495 return -EILSEQ;
496 }
497 memcpy(prng_data->prev, buf, nbytes);
498 }
499
500 return nbytes;
501}
502
503
504/*** file io functions ***/
505
506static int prng_open(struct inode *inode, struct file *file)
507{
508 return nonseekable_open(inode, file);
509}
510
511
512static ssize_t prng_tdes_read(struct file *file, char __user *ubuf,
513 size_t nbytes, loff_t *ppos)
514{
515 int chunk, n, ret = 0;
516
517 /* lock prng_data struct */
518 if (mutex_lock_interruptible(&prng_data->mutex))
519 return -ERESTARTSYS;
520
521 while (nbytes) {
522 if (need_resched()) {
523 if (signal_pending(current)) {
524 if (ret == 0)
525 ret = -ERESTARTSYS;
526 break;
527 }
528 /* give mutex free before calling schedule() */
529 mutex_unlock(&prng_data->mutex);
530 schedule();
531 /* occopy mutex again */
532 if (mutex_lock_interruptible(&prng_data->mutex)) {
533 if (ret == 0)
534 ret = -ERESTARTSYS;
535 return ret;
536 }
537 }
538
539 /*
540 * we lose some random bytes if an attacker issues
541 * reads < 8 bytes, but we don't care
542 */
543 chunk = min_t(int, nbytes, prng_chunk_size);
544
545 /* PRNG only likes multiples of 8 bytes */
546 n = (chunk + 7) & -8;
547
548 if (prng_data->prngws.reseed_counter > prng_reseed_limit)
549 prng_tdes_seed(8);
550
551 /* if the CPU supports PRNG stckf is present too */
552 *((unsigned long long *)prng_data->buf) = get_tod_clock_fast();
553
554 /*
555 * Beside the STCKF the input for the TDES-EDE is the output
556 * of the last operation. We differ here from X9.17 since we
557 * only store one timestamp into the buffer. Padding the whole
558 * buffer with timestamps does not improve security, since
559 * successive stckf have nearly constant offsets.
560 * If an attacker knows the first timestamp it would be
561 * trivial to guess the additional values. One timestamp
562 * is therefore enough and still guarantees unique input values.
563 *
564 * Note: you can still get strict X9.17 conformity by setting
565 * prng_chunk_size to 8 bytes.
566 */
567 cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
568 prng_data->buf, prng_data->buf, n);
569
570 prng_data->prngws.byte_counter += n;
571 prng_data->prngws.reseed_counter += n;
572
573 if (copy_to_user(ubuf, prng_data->buf, chunk)) {
574 ret = -EFAULT;
575 break;
576 }
577
578 nbytes -= chunk;
579 ret += chunk;
580 ubuf += chunk;
581 }
582
583 /* unlock prng_data struct */
584 mutex_unlock(&prng_data->mutex);
585
586 return ret;
587}
588
589
590static ssize_t prng_sha512_read(struct file *file, char __user *ubuf,
591 size_t nbytes, loff_t *ppos)
592{
593 int n, ret = 0;
594 u8 *p;
595
596 /* if errorflag is set do nothing and return 'broken pipe' */
597 if (prng_errorflag)
598 return -EPIPE;
599
600 /* lock prng_data struct */
601 if (mutex_lock_interruptible(&prng_data->mutex))
602 return -ERESTARTSYS;
603
604 while (nbytes) {
605 if (need_resched()) {
606 if (signal_pending(current)) {
607 if (ret == 0)
608 ret = -ERESTARTSYS;
609 break;
610 }
611 /* give mutex free before calling schedule() */
612 mutex_unlock(&prng_data->mutex);
613 schedule();
614 /* occopy mutex again */
615 if (mutex_lock_interruptible(&prng_data->mutex)) {
616 if (ret == 0)
617 ret = -ERESTARTSYS;
618 return ret;
619 }
620 }
621 if (prng_data->rest) {
622 /* push left over random bytes from the previous read */
623 p = prng_data->buf + prng_chunk_size - prng_data->rest;
624 n = (nbytes < prng_data->rest) ?
625 nbytes : prng_data->rest;
626 prng_data->rest -= n;
627 } else {
628 /* generate one chunk of random bytes into read buf */
629 p = prng_data->buf;
630 n = prng_sha512_generate(p, prng_chunk_size);
631 if (n < 0) {
632 ret = n;
633 break;
634 }
635 if (nbytes < prng_chunk_size) {
636 n = nbytes;
637 prng_data->rest = prng_chunk_size - n;
638 } else {
639 n = prng_chunk_size;
640 prng_data->rest = 0;
641 }
642 }
643 if (copy_to_user(ubuf, p, n)) {
644 ret = -EFAULT;
645 break;
646 }
647 memzero_explicit(p, n);
648 ubuf += n;
649 nbytes -= n;
650 ret += n;
651 }
652
653 /* unlock prng_data struct */
654 mutex_unlock(&prng_data->mutex);
655
656 return ret;
657}
658
659
660/*** sysfs stuff ***/
661
662static const struct file_operations prng_sha512_fops = {
663 .owner = THIS_MODULE,
664 .open = &prng_open,
665 .release = NULL,
666 .read = &prng_sha512_read,
667 .llseek = noop_llseek,
668};
669static const struct file_operations prng_tdes_fops = {
670 .owner = THIS_MODULE,
671 .open = &prng_open,
672 .release = NULL,
673 .read = &prng_tdes_read,
674 .llseek = noop_llseek,
675};
676
677static struct miscdevice prng_sha512_dev = {
678 .name = "prandom",
679 .minor = MISC_DYNAMIC_MINOR,
680 .mode = 0644,
681 .fops = &prng_sha512_fops,
682};
683static struct miscdevice prng_tdes_dev = {
684 .name = "prandom",
685 .minor = MISC_DYNAMIC_MINOR,
686 .mode = 0644,
687 .fops = &prng_tdes_fops,
688};
689
690
691/* chunksize attribute (ro) */
692static ssize_t prng_chunksize_show(struct device *dev,
693 struct device_attribute *attr,
694 char *buf)
695{
696 return snprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
697}
698static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);
699
700/* counter attribute (ro) */
701static ssize_t prng_counter_show(struct device *dev,
702 struct device_attribute *attr,
703 char *buf)
704{
705 u64 counter;
706
707 if (mutex_lock_interruptible(&prng_data->mutex))
708 return -ERESTARTSYS;
709 if (prng_mode == PRNG_MODE_SHA512)
710 counter = prng_data->prnows.stream_bytes;
711 else
712 counter = prng_data->prngws.byte_counter;
713 mutex_unlock(&prng_data->mutex);
714
715 return snprintf(buf, PAGE_SIZE, "%llu\n", counter);
716}
717static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);
718
719/* errorflag attribute (ro) */
720static ssize_t prng_errorflag_show(struct device *dev,
721 struct device_attribute *attr,
722 char *buf)
723{
724 return snprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
725}
726static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);
727
728/* mode attribute (ro) */
729static ssize_t prng_mode_show(struct device *dev,
730 struct device_attribute *attr,
731 char *buf)
732{
733 if (prng_mode == PRNG_MODE_TDES)
734 return snprintf(buf, PAGE_SIZE, "TDES\n");
735 else
736 return snprintf(buf, PAGE_SIZE, "SHA512\n");
737}
738static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);
739
740/* reseed attribute (w) */
741static ssize_t prng_reseed_store(struct device *dev,
742 struct device_attribute *attr,
743 const char *buf, size_t count)
744{
745 if (mutex_lock_interruptible(&prng_data->mutex))
746 return -ERESTARTSYS;
747 prng_sha512_reseed();
748 mutex_unlock(&prng_data->mutex);
749
750 return count;
751}
752static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store);
753
754/* reseed limit attribute (rw) */
755static ssize_t prng_reseed_limit_show(struct device *dev,
756 struct device_attribute *attr,
757 char *buf)
758{
759 return snprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
760}
761static ssize_t prng_reseed_limit_store(struct device *dev,
762 struct device_attribute *attr,
763 const char *buf, size_t count)
764{
765 unsigned limit;
766
767 if (sscanf(buf, "%u\n", &limit) != 1)
768 return -EINVAL;
769
770 if (prng_mode == PRNG_MODE_SHA512) {
771 if (limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
772 return -EINVAL;
773 } else {
774 if (limit < PRNG_RESEED_LIMIT_TDES_LOWER)
775 return -EINVAL;
776 }
777
778 prng_reseed_limit = limit;
779
780 return count;
781}
782static DEVICE_ATTR(reseed_limit, 0644,
783 prng_reseed_limit_show, prng_reseed_limit_store);
784
785/* strength attribute (ro) */
786static ssize_t prng_strength_show(struct device *dev,
787 struct device_attribute *attr,
788 char *buf)
789{
790 return snprintf(buf, PAGE_SIZE, "256\n");
791}
792static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);
793
794static struct attribute *prng_sha512_dev_attrs[] = {
795 &dev_attr_errorflag.attr,
796 &dev_attr_chunksize.attr,
797 &dev_attr_byte_counter.attr,
798 &dev_attr_mode.attr,
799 &dev_attr_reseed.attr,
800 &dev_attr_reseed_limit.attr,
801 &dev_attr_strength.attr,
802 NULL
803};
804static struct attribute *prng_tdes_dev_attrs[] = {
805 &dev_attr_chunksize.attr,
806 &dev_attr_byte_counter.attr,
807 &dev_attr_mode.attr,
808 NULL
809};
810
811static struct attribute_group prng_sha512_dev_attr_group = {
812 .attrs = prng_sha512_dev_attrs
813};
814static struct attribute_group prng_tdes_dev_attr_group = {
815 .attrs = prng_tdes_dev_attrs
816};
817
818
819/*** module init and exit ***/
820
821static int __init prng_init(void)
822{
823 int ret;
824
825 /* check if the CPU has a PRNG */
826 if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG))
827 return -ENODEV;
828
829 /* check if TRNG subfunction is available */
830 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
831 trng_available = true;
832
833 /* choose prng mode */
834 if (prng_mode != PRNG_MODE_TDES) {
835 /* check for MSA5 support for PRNO operations */
836 if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN)) {
837 if (prng_mode == PRNG_MODE_SHA512) {
838 pr_err("The prng module cannot "
839 "start in SHA-512 mode\n");
840 return -ENODEV;
841 }
842 prng_mode = PRNG_MODE_TDES;
843 } else
844 prng_mode = PRNG_MODE_SHA512;
845 }
846
847 if (prng_mode == PRNG_MODE_SHA512) {
848
849 /* SHA512 mode */
850
851 if (prng_chunk_size < PRNG_CHUNKSIZE_SHA512_MIN
852 || prng_chunk_size > PRNG_CHUNKSIZE_SHA512_MAX)
853 return -EINVAL;
854 prng_chunk_size = (prng_chunk_size + 0x3f) & ~0x3f;
855
856 if (prng_reseed_limit == 0)
857 prng_reseed_limit = PRNG_RESEED_LIMIT_SHA512;
858 else if (prng_reseed_limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
859 return -EINVAL;
860
861 ret = prng_sha512_instantiate();
862 if (ret)
863 goto out;
864
865 ret = misc_register(&prng_sha512_dev);
866 if (ret) {
867 prng_sha512_deinstantiate();
868 goto out;
869 }
870 ret = sysfs_create_group(&prng_sha512_dev.this_device->kobj,
871 &prng_sha512_dev_attr_group);
872 if (ret) {
873 misc_deregister(&prng_sha512_dev);
874 prng_sha512_deinstantiate();
875 goto out;
876 }
877
878 } else {
879
880 /* TDES mode */
881
882 if (prng_chunk_size < PRNG_CHUNKSIZE_TDES_MIN
883 || prng_chunk_size > PRNG_CHUNKSIZE_TDES_MAX)
884 return -EINVAL;
885 prng_chunk_size = (prng_chunk_size + 0x07) & ~0x07;
886
887 if (prng_reseed_limit == 0)
888 prng_reseed_limit = PRNG_RESEED_LIMIT_TDES;
889 else if (prng_reseed_limit < PRNG_RESEED_LIMIT_TDES_LOWER)
890 return -EINVAL;
891
892 ret = prng_tdes_instantiate();
893 if (ret)
894 goto out;
895
896 ret = misc_register(&prng_tdes_dev);
897 if (ret) {
898 prng_tdes_deinstantiate();
899 goto out;
900 }
901 ret = sysfs_create_group(&prng_tdes_dev.this_device->kobj,
902 &prng_tdes_dev_attr_group);
903 if (ret) {
904 misc_deregister(&prng_tdes_dev);
905 prng_tdes_deinstantiate();
906 goto out;
907 }
908
909 }
910
911out:
912 return ret;
913}
914
915
916static void __exit prng_exit(void)
917{
918 if (prng_mode == PRNG_MODE_SHA512) {
919 sysfs_remove_group(&prng_sha512_dev.this_device->kobj,
920 &prng_sha512_dev_attr_group);
921 misc_deregister(&prng_sha512_dev);
922 prng_sha512_deinstantiate();
923 } else {
924 sysfs_remove_group(&prng_tdes_dev.this_device->kobj,
925 &prng_tdes_dev_attr_group);
926 misc_deregister(&prng_tdes_dev);
927 prng_tdes_deinstantiate();
928 }
929}
930
931module_cpu_feature_match(MSA, prng_init);
932module_exit(prng_exit);
1/*
2 * Copyright IBM Corp. 2006, 2007
3 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
4 * Driver for the s390 pseudo random number generator
5 */
6#include <linux/fs.h>
7#include <linux/init.h>
8#include <linux/kernel.h>
9#include <linux/miscdevice.h>
10#include <linux/module.h>
11#include <linux/moduleparam.h>
12#include <linux/random.h>
13#include <linux/slab.h>
14#include <asm/debug.h>
15#include <asm/uaccess.h>
16
17#include "crypt_s390.h"
18
19MODULE_LICENSE("GPL");
20MODULE_AUTHOR("Jan Glauber <jan.glauber@de.ibm.com>");
21MODULE_DESCRIPTION("s390 PRNG interface");
22
23static int prng_chunk_size = 256;
24module_param(prng_chunk_size, int, S_IRUSR | S_IRGRP | S_IROTH);
25MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes");
26
27static int prng_entropy_limit = 4096;
28module_param(prng_entropy_limit, int, S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR);
29MODULE_PARM_DESC(prng_entropy_limit,
30 "PRNG add entropy after that much bytes were produced");
31
32/*
33 * Any one who considers arithmetical methods of producing random digits is,
34 * of course, in a state of sin. -- John von Neumann
35 */
36
37struct s390_prng_data {
38 unsigned long count; /* how many bytes were produced */
39 char *buf;
40};
41
42static struct s390_prng_data *p;
43
44/* copied from libica, use a non-zero initial parameter block */
45static unsigned char parm_block[32] = {
460x0F,0x2B,0x8E,0x63,0x8C,0x8E,0xD2,0x52,0x64,0xB7,0xA0,0x7B,0x75,0x28,0xB8,0xF4,
470x75,0x5F,0xD2,0xA6,0x8D,0x97,0x11,0xFF,0x49,0xD8,0x23,0xF3,0x7E,0x21,0xEC,0xA0,
48};
49
50static int prng_open(struct inode *inode, struct file *file)
51{
52 return nonseekable_open(inode, file);
53}
54
55static void prng_add_entropy(void)
56{
57 __u64 entropy[4];
58 unsigned int i;
59 int ret;
60
61 for (i = 0; i < 16; i++) {
62 ret = crypt_s390_kmc(KMC_PRNG, parm_block, (char *)entropy,
63 (char *)entropy, sizeof(entropy));
64 BUG_ON(ret < 0 || ret != sizeof(entropy));
65 memcpy(parm_block, entropy, sizeof(entropy));
66 }
67}
68
69static void prng_seed(int nbytes)
70{
71 char buf[16];
72 int i = 0;
73
74 BUG_ON(nbytes > 16);
75 get_random_bytes(buf, nbytes);
76
77 /* Add the entropy */
78 while (nbytes >= 8) {
79 *((__u64 *)parm_block) ^= *((__u64 *)(buf+i));
80 prng_add_entropy();
81 i += 8;
82 nbytes -= 8;
83 }
84 prng_add_entropy();
85}
86
87static ssize_t prng_read(struct file *file, char __user *ubuf, size_t nbytes,
88 loff_t *ppos)
89{
90 int chunk, n;
91 int ret = 0;
92 int tmp;
93
94 /* nbytes can be arbitrary length, we split it into chunks */
95 while (nbytes) {
96 /* same as in extract_entropy_user in random.c */
97 if (need_resched()) {
98 if (signal_pending(current)) {
99 if (ret == 0)
100 ret = -ERESTARTSYS;
101 break;
102 }
103 schedule();
104 }
105
106 /*
107 * we lose some random bytes if an attacker issues
108 * reads < 8 bytes, but we don't care
109 */
110 chunk = min_t(int, nbytes, prng_chunk_size);
111
112 /* PRNG only likes multiples of 8 bytes */
113 n = (chunk + 7) & -8;
114
115 if (p->count > prng_entropy_limit)
116 prng_seed(8);
117
118 /* if the CPU supports PRNG stckf is present too */
119 asm volatile(".insn s,0xb27c0000,%0"
120 : "=m" (*((unsigned long long *)p->buf)) : : "cc");
121
122 /*
123 * Beside the STCKF the input for the TDES-EDE is the output
124 * of the last operation. We differ here from X9.17 since we
125 * only store one timestamp into the buffer. Padding the whole
126 * buffer with timestamps does not improve security, since
127 * successive stckf have nearly constant offsets.
128 * If an attacker knows the first timestamp it would be
129 * trivial to guess the additional values. One timestamp
130 * is therefore enough and still guarantees unique input values.
131 *
132 * Note: you can still get strict X9.17 conformity by setting
133 * prng_chunk_size to 8 bytes.
134 */
135 tmp = crypt_s390_kmc(KMC_PRNG, parm_block, p->buf, p->buf, n);
136 BUG_ON((tmp < 0) || (tmp != n));
137
138 p->count += n;
139
140 if (copy_to_user(ubuf, p->buf, chunk))
141 return -EFAULT;
142
143 nbytes -= chunk;
144 ret += chunk;
145 ubuf += chunk;
146 }
147 return ret;
148}
149
150static const struct file_operations prng_fops = {
151 .owner = THIS_MODULE,
152 .open = &prng_open,
153 .release = NULL,
154 .read = &prng_read,
155 .llseek = noop_llseek,
156};
157
158static struct miscdevice prng_dev = {
159 .name = "prandom",
160 .minor = MISC_DYNAMIC_MINOR,
161 .fops = &prng_fops,
162};
163
164static int __init prng_init(void)
165{
166 int ret;
167
168 /* check if the CPU has a PRNG */
169 if (!crypt_s390_func_available(KMC_PRNG, CRYPT_S390_MSA))
170 return -EOPNOTSUPP;
171
172 if (prng_chunk_size < 8)
173 return -EINVAL;
174
175 p = kmalloc(sizeof(struct s390_prng_data), GFP_KERNEL);
176 if (!p)
177 return -ENOMEM;
178 p->count = 0;
179
180 p->buf = kmalloc(prng_chunk_size, GFP_KERNEL);
181 if (!p->buf) {
182 ret = -ENOMEM;
183 goto out_free;
184 }
185
186 /* initialize the PRNG, add 128 bits of entropy */
187 prng_seed(16);
188
189 ret = misc_register(&prng_dev);
190 if (ret)
191 goto out_buf;
192 return 0;
193
194out_buf:
195 kfree(p->buf);
196out_free:
197 kfree(p);
198 return ret;
199}
200
201static void __exit prng_exit(void)
202{
203 /* wipe me */
204 kzfree(p->buf);
205 kfree(p);
206
207 misc_deregister(&prng_dev);
208}
209
210module_init(prng_init);
211module_exit(prng_exit);