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
31 MODULE_LICENSE("GPL");
32 MODULE_AUTHOR("IBM Corporation");
33 MODULE_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
40 static unsigned int prng_mode = PRNG_MODE_AUTO;
41 module_param_named(mode, prng_mode, int, 0);
42 MODULE_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
50 static unsigned int prng_chunk_size = 256;
51 module_param_named(chunksize, prng_chunk_size, int, 0);
52 MODULE_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
60 static unsigned int prng_reseed_limit;
61 module_param_named(reseed_limit, prng_reseed_limit, int, 0);
62 MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit");
63
64 static 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
71 static 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
80 struct prng_ws_s {
81 u8 parm_block[32];
82 u32 reseed_counter;
83 u64 byte_counter;
84 };
85
86 struct prno_ws_s {
87 u32 res;
88 u32 reseed_counter;
89 u64 stream_bytes;
90 u8 V[112];
91 u8 C[112];
92 };
93
94 struct 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
105 static struct prng_data_s *prng_data;
106
107 /* initial parameter block for tdes mode, copied from libica */
108 static 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 */
generate_entropy(u8 * ebuf,size_t nbytes)135 static 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
prng_tdes_add_entropy(void)187 static 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
prng_tdes_seed(int nbytes)201 static 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
prng_tdes_instantiate(void)222 static 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
prng_tdes_deinstantiate(void)248 static void prng_tdes_deinstantiate(void)
249 {
250 pr_debug("The prng module stopped "
251 "after running in triple DES mode\n");
252 kfree_sensitive(prng_data);
253 }
254
255
256 /*** sha512 functions ***/
257
prng_sha512_selftest(void)258 static 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
prng_sha512_instantiate(void)368 static 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 store_tod_clock_ext((union tod_clock *)(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
436 outfree:
437 kfree(prng_data);
438 return ret;
439 }
440
441
prng_sha512_deinstantiate(void)442 static void prng_sha512_deinstantiate(void)
443 {
444 pr_debug("The prng module stopped after running in SHA-512 mode\n");
445 kfree_sensitive(prng_data);
446 }
447
448
prng_sha512_reseed(void)449 static 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
prng_sha512_generate(u8 * buf,size_t nbytes)476 static 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
prng_open(struct inode * inode,struct file * file)506 static int prng_open(struct inode *inode, struct file *file)
507 {
508 return nonseekable_open(inode, file);
509 }
510
511
prng_tdes_read(struct file * file,char __user * ubuf,size_t nbytes,loff_t * ppos)512 static 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 /* occupy 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
prng_sha512_read(struct file * file,char __user * ubuf,size_t nbytes,loff_t * ppos)590 static 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
662 static 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 };
669 static 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
677 /* chunksize attribute (ro) */
prng_chunksize_show(struct device * dev,struct device_attribute * attr,char * buf)678 static ssize_t prng_chunksize_show(struct device *dev,
679 struct device_attribute *attr,
680 char *buf)
681 {
682 return scnprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
683 }
684 static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);
685
686 /* counter attribute (ro) */
prng_counter_show(struct device * dev,struct device_attribute * attr,char * buf)687 static ssize_t prng_counter_show(struct device *dev,
688 struct device_attribute *attr,
689 char *buf)
690 {
691 u64 counter;
692
693 if (mutex_lock_interruptible(&prng_data->mutex))
694 return -ERESTARTSYS;
695 if (prng_mode == PRNG_MODE_SHA512)
696 counter = prng_data->prnows.stream_bytes;
697 else
698 counter = prng_data->prngws.byte_counter;
699 mutex_unlock(&prng_data->mutex);
700
701 return scnprintf(buf, PAGE_SIZE, "%llu\n", counter);
702 }
703 static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);
704
705 /* errorflag attribute (ro) */
prng_errorflag_show(struct device * dev,struct device_attribute * attr,char * buf)706 static ssize_t prng_errorflag_show(struct device *dev,
707 struct device_attribute *attr,
708 char *buf)
709 {
710 return scnprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
711 }
712 static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);
713
714 /* mode attribute (ro) */
prng_mode_show(struct device * dev,struct device_attribute * attr,char * buf)715 static ssize_t prng_mode_show(struct device *dev,
716 struct device_attribute *attr,
717 char *buf)
718 {
719 if (prng_mode == PRNG_MODE_TDES)
720 return scnprintf(buf, PAGE_SIZE, "TDES\n");
721 else
722 return scnprintf(buf, PAGE_SIZE, "SHA512\n");
723 }
724 static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);
725
726 /* reseed attribute (w) */
prng_reseed_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)727 static ssize_t prng_reseed_store(struct device *dev,
728 struct device_attribute *attr,
729 const char *buf, size_t count)
730 {
731 if (mutex_lock_interruptible(&prng_data->mutex))
732 return -ERESTARTSYS;
733 prng_sha512_reseed();
734 mutex_unlock(&prng_data->mutex);
735
736 return count;
737 }
738 static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store);
739
740 /* reseed limit attribute (rw) */
prng_reseed_limit_show(struct device * dev,struct device_attribute * attr,char * buf)741 static ssize_t prng_reseed_limit_show(struct device *dev,
742 struct device_attribute *attr,
743 char *buf)
744 {
745 return scnprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
746 }
prng_reseed_limit_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)747 static ssize_t prng_reseed_limit_store(struct device *dev,
748 struct device_attribute *attr,
749 const char *buf, size_t count)
750 {
751 unsigned limit;
752
753 if (sscanf(buf, "%u\n", &limit) != 1)
754 return -EINVAL;
755
756 if (prng_mode == PRNG_MODE_SHA512) {
757 if (limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
758 return -EINVAL;
759 } else {
760 if (limit < PRNG_RESEED_LIMIT_TDES_LOWER)
761 return -EINVAL;
762 }
763
764 prng_reseed_limit = limit;
765
766 return count;
767 }
768 static DEVICE_ATTR(reseed_limit, 0644,
769 prng_reseed_limit_show, prng_reseed_limit_store);
770
771 /* strength attribute (ro) */
prng_strength_show(struct device * dev,struct device_attribute * attr,char * buf)772 static ssize_t prng_strength_show(struct device *dev,
773 struct device_attribute *attr,
774 char *buf)
775 {
776 return scnprintf(buf, PAGE_SIZE, "256\n");
777 }
778 static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);
779
780 static struct attribute *prng_sha512_dev_attrs[] = {
781 &dev_attr_errorflag.attr,
782 &dev_attr_chunksize.attr,
783 &dev_attr_byte_counter.attr,
784 &dev_attr_mode.attr,
785 &dev_attr_reseed.attr,
786 &dev_attr_reseed_limit.attr,
787 &dev_attr_strength.attr,
788 NULL
789 };
790 ATTRIBUTE_GROUPS(prng_sha512_dev);
791
792 static struct attribute *prng_tdes_dev_attrs[] = {
793 &dev_attr_chunksize.attr,
794 &dev_attr_byte_counter.attr,
795 &dev_attr_mode.attr,
796 NULL
797 };
798 ATTRIBUTE_GROUPS(prng_tdes_dev);
799
800 static struct miscdevice prng_sha512_dev = {
801 .name = "prandom",
802 .minor = MISC_DYNAMIC_MINOR,
803 .mode = 0644,
804 .fops = &prng_sha512_fops,
805 .groups = prng_sha512_dev_groups,
806 };
807
808 static struct miscdevice prng_tdes_dev = {
809 .name = "prandom",
810 .minor = MISC_DYNAMIC_MINOR,
811 .mode = 0644,
812 .fops = &prng_tdes_fops,
813 .groups = prng_tdes_dev_groups,
814 };
815
816
817 /*** module init and exit ***/
818
prng_init(void)819 static int __init prng_init(void)
820 {
821 int ret;
822
823 /* check if the CPU has a PRNG */
824 if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG))
825 return -ENODEV;
826
827 /* check if TRNG subfunction is available */
828 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
829 trng_available = true;
830
831 /* choose prng mode */
832 if (prng_mode != PRNG_MODE_TDES) {
833 /* check for MSA5 support for PRNO operations */
834 if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN)) {
835 if (prng_mode == PRNG_MODE_SHA512) {
836 pr_err("The prng module cannot "
837 "start in SHA-512 mode\n");
838 return -ENODEV;
839 }
840 prng_mode = PRNG_MODE_TDES;
841 } else
842 prng_mode = PRNG_MODE_SHA512;
843 }
844
845 if (prng_mode == PRNG_MODE_SHA512) {
846
847 /* SHA512 mode */
848
849 if (prng_chunk_size < PRNG_CHUNKSIZE_SHA512_MIN
850 || prng_chunk_size > PRNG_CHUNKSIZE_SHA512_MAX)
851 return -EINVAL;
852 prng_chunk_size = (prng_chunk_size + 0x3f) & ~0x3f;
853
854 if (prng_reseed_limit == 0)
855 prng_reseed_limit = PRNG_RESEED_LIMIT_SHA512;
856 else if (prng_reseed_limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
857 return -EINVAL;
858
859 ret = prng_sha512_instantiate();
860 if (ret)
861 goto out;
862
863 ret = misc_register(&prng_sha512_dev);
864 if (ret) {
865 prng_sha512_deinstantiate();
866 goto out;
867 }
868
869 } else {
870
871 /* TDES mode */
872
873 if (prng_chunk_size < PRNG_CHUNKSIZE_TDES_MIN
874 || prng_chunk_size > PRNG_CHUNKSIZE_TDES_MAX)
875 return -EINVAL;
876 prng_chunk_size = (prng_chunk_size + 0x07) & ~0x07;
877
878 if (prng_reseed_limit == 0)
879 prng_reseed_limit = PRNG_RESEED_LIMIT_TDES;
880 else if (prng_reseed_limit < PRNG_RESEED_LIMIT_TDES_LOWER)
881 return -EINVAL;
882
883 ret = prng_tdes_instantiate();
884 if (ret)
885 goto out;
886
887 ret = misc_register(&prng_tdes_dev);
888 if (ret) {
889 prng_tdes_deinstantiate();
890 goto out;
891 }
892 }
893
894 out:
895 return ret;
896 }
897
898
prng_exit(void)899 static void __exit prng_exit(void)
900 {
901 if (prng_mode == PRNG_MODE_SHA512) {
902 misc_deregister(&prng_sha512_dev);
903 prng_sha512_deinstantiate();
904 } else {
905 misc_deregister(&prng_tdes_dev);
906 prng_tdes_deinstantiate();
907 }
908 }
909
910 module_cpu_feature_match(S390_CPU_FEATURE_MSA, prng_init);
911 module_exit(prng_exit);
912