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 | */ |
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(buf: 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(s: pblock, count: sizeof(pblock)); |
179 | memzero_explicit(s: pg, PAGE_SIZE); |
180 | free_page((unsigned long)pg); |
181 | return ret; |
182 | } |
183 | |
184 | |
185 | /*** tdes functions ***/ |
186 | |
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 | |
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, len: 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 | |
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(size: 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(nbytes: 16); |
243 | |
244 | return 0; |
245 | } |
246 | |
247 | |
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(objp: prng_data); |
253 | } |
254 | |
255 | |
256 | /*** sha512 functions ***/ |
257 | |
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(p: ws.V, q: V0, size: sizeof(V0)) != 0 |
343 | || memcmp(p: ws.C, q: C0, size: 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(p: buf, q: random, size: 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 | |
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(size: 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(ebuf: seed, nbytes: 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(s: seed, count: 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(objp: prng_data); |
438 | return ret; |
439 | } |
440 | |
441 | |
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(objp: prng_data); |
446 | } |
447 | |
448 | |
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(ebuf: seed, nbytes: 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(s: seed, count: sizeof(seed)); |
471 | |
472 | return 0; |
473 | } |
474 | |
475 | |
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(p: prng_data->prev, q: buf, size: 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 | |
506 | static int prng_open(struct inode *inode, struct file *file) |
507 | { |
508 | return nonseekable_open(inode, filp: file); |
509 | } |
510 | |
511 | |
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(lock: &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(nbytes: 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(to: ubuf, from: prng_data->buf, n: 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(lock: &prng_data->mutex); |
585 | |
586 | return ret; |
587 | } |
588 | |
589 | |
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(lock: &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(buf: p, nbytes: 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(to: ubuf, from: p, n)) { |
644 | ret = -EFAULT; |
645 | break; |
646 | } |
647 | memzero_explicit(s: p, count: n); |
648 | ubuf += n; |
649 | nbytes -= n; |
650 | ret += n; |
651 | } |
652 | |
653 | /* unlock prng_data struct */ |
654 | mutex_unlock(lock: &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) */ |
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, fmt: "%u\n" , prng_chunk_size); |
683 | } |
684 | static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL); |
685 | |
686 | /* counter attribute (ro) */ |
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(lock: &prng_data->mutex); |
700 | |
701 | return scnprintf(buf, PAGE_SIZE, fmt: "%llu\n" , counter); |
702 | } |
703 | static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL); |
704 | |
705 | /* errorflag attribute (ro) */ |
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, fmt: "%d\n" , prng_errorflag); |
711 | } |
712 | static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL); |
713 | |
714 | /* mode attribute (ro) */ |
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, fmt: "TDES\n" ); |
721 | else |
722 | return scnprintf(buf, PAGE_SIZE, fmt: "SHA512\n" ); |
723 | } |
724 | static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL); |
725 | |
726 | /* reseed attribute (w) */ |
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(lock: &prng_data->mutex); |
735 | |
736 | return count; |
737 | } |
738 | static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store); |
739 | |
740 | /* reseed limit attribute (rw) */ |
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, fmt: "%u\n" , prng_reseed_limit); |
746 | } |
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) */ |
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, fmt: "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 | |
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(misc: &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(misc: &prng_tdes_dev); |
888 | if (ret) { |
889 | prng_tdes_deinstantiate(); |
890 | goto out; |
891 | } |
892 | } |
893 | |
894 | out: |
895 | return ret; |
896 | } |
897 | |
898 | |
899 | static void __exit prng_exit(void) |
900 | { |
901 | if (prng_mode == PRNG_MODE_SHA512) { |
902 | misc_deregister(misc: &prng_sha512_dev); |
903 | prng_sha512_deinstantiate(); |
904 | } else { |
905 | misc_deregister(misc: &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 | |