arch/s390/crypto/prng.c

   1 /*
   2  * Copyright IBM Corp. 2006, 2015
   3  * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
   4  *            Harald Freudenberger <freude@de.ibm.com>
   5  * Driver for the s390 pseudo random number generator
   6  */
   7
   8 #define KMSG_COMPONENT "prng"
   9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11 #include <linux/fs.h>
  12 #include <linux/fips.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/device.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/mutex.h>
  20 #include <linux/cpufeature.h>
  21 #include <linux/random.h>
  22 #include <linux/slab.h>
  23 #include <asm/debug.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/timex.h>
  26 #include <asm/cpacf.h>
  27
  28 MODULE_LICENSE("GPL");
  29 MODULE_AUTHOR("IBM Corporation");
  30 MODULE_DESCRIPTION("s390 PRNG interface");
  31
  32
  33 #define PRNG_MODE_AUTO    0
  34 #define PRNG_MODE_TDES    1
  35 #define PRNG_MODE_SHA512  2
  36
  37 static unsigned int prng_mode = PRNG_MODE_AUTO;
  38 module_param_named(mode, prng_mode, int, 0);
  39 MODULE_PARM_DESC(prng_mode, "PRNG mode: 0 - auto, 1 - TDES, 2 - SHA512");
  40
  41
  42 #define PRNG_CHUNKSIZE_TDES_MIN   8
  43 #define PRNG_CHUNKSIZE_TDES_MAX   (64*1024)
  44 #define PRNG_CHUNKSIZE_SHA512_MIN 64
  45 #define PRNG_CHUNKSIZE_SHA512_MAX (64*1024)
  46
  47 static unsigned int prng_chunk_size = 256;
  48 module_param_named(chunksize, prng_chunk_size, int, 0);
  49 MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes");
  50
  51
  52 #define PRNG_RESEED_LIMIT_TDES           4096
  53 #define PRNG_RESEED_LIMIT_TDES_LOWER     4096
  54 #define PRNG_RESEED_LIMIT_SHA512       100000
  55 #define PRNG_RESEED_LIMIT_SHA512_LOWER  10000
  56
  57 static unsigned int prng_reseed_limit;
  58 module_param_named(reseed_limit, prng_reseed_limit, int, 0);
  59 MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit");
  60
  61
  62 /*
  63  * Any one who considers arithmetical methods of producing random digits is,
  64  * of course, in a state of sin. -- John von Neumann
  65  */
  66
  67 static int prng_errorflag;
  68
  69 #define PRNG_GEN_ENTROPY_FAILED  1
  70 #define PRNG_SELFTEST_FAILED     2
  71 #define PRNG_INSTANTIATE_FAILED  3
  72 #define PRNG_SEED_FAILED         4
  73 #define PRNG_RESEED_FAILED       5
  74 #define PRNG_GEN_FAILED          6
  75
  76 struct prng_ws_s {
  77         u8  parm_block[32];
  78         u32 reseed_counter;
  79         u64 byte_counter;
  80 };
  81
  82 struct ppno_ws_s {
  83         u32 res;
  84         u32 reseed_counter;
  85         u64 stream_bytes;
  86         u8  V[112];
  87         u8  C[112];
  88 };
  89
  90 struct prng_data_s {
  91         struct mutex mutex;
  92         union {
  93                 struct prng_ws_s prngws;
  94                 struct ppno_ws_s ppnows;
  95         };
  96         u8 *buf;
  97         u32 rest;
  98         u8 *prev;
  99 };
 100
 101 static struct prng_data_s *prng_data;
 102
 103 /* initial parameter block for tdes mode, copied from libica */
 104 static const u8 initial_parm_block[32] __initconst = {
 105         0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
 106         0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
 107         0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
 108         0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 };
 109
 110
 111 /*** helper functions ***/
 112
 113 static int generate_entropy(u8 *ebuf, size_t nbytes)
 114 {
 115         int n, ret = 0;
 116         u8 *pg, *h, hash[32];
 117
 118         pg = (u8 *) __get_free_page(GFP_KERNEL);
 119         if (!pg) {
 120                 prng_errorflag = PRNG_GEN_ENTROPY_FAILED;
 121                 return -ENOMEM;
 122         }
 123
 124         while (nbytes) {
 125                 /* fill page with urandom bytes */
 126                 get_random_bytes(pg, PAGE_SIZE);
 127                 /* exor page with stckf values */
 128                 for (n = 0; n < PAGE_SIZE / sizeof(u64); n++) {
 129                         u64 *p = ((u64 *)pg) + n;
 130                         *p ^= get_tod_clock_fast();
 131                 }
 132                 n = (nbytes < sizeof(hash)) ? nbytes : sizeof(hash);
 133                 if (n < sizeof(hash))
 134                         h = hash;
 135                 else
 136                         h = ebuf;
 137                 /* generate sha256 from this page */
 138                 cpacf_kimd(CPACF_KIMD_SHA_256, h, pg, PAGE_SIZE);
 139                 if (n < sizeof(hash))
 140                         memcpy(ebuf, hash, n);
 141                 ret += n;
 142                 ebuf += n;
 143                 nbytes -= n;
 144         }
 145
 146         free_page((unsigned long)pg);
 147         return ret;
 148 }
 149
 150
 151 /*** tdes functions ***/
 152
 153 static void prng_tdes_add_entropy(void)
 154 {
 155         __u64 entropy[4];
 156         unsigned int i;
 157
 158         for (i = 0; i < 16; i++) {
 159                 cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
 160                           (char *) entropy, (char *) entropy,
 161                           sizeof(entropy));
 162                 memcpy(prng_data->prngws.parm_block, entropy, sizeof(entropy));
 163         }
 164 }
 165
 166
 167 static void prng_tdes_seed(int nbytes)
 168 {
 169         char buf[16];
 170         int i = 0;
 171
 172         BUG_ON(nbytes > sizeof(buf));
 173
 174         get_random_bytes(buf, nbytes);
 175
 176         /* Add the entropy */
 177         while (nbytes >= 8) {
 178                 *((__u64 *)prng_data->prngws.parm_block) ^= *((__u64 *)(buf+i));
 179                 prng_tdes_add_entropy();
 180                 i += 8;
 181                 nbytes -= 8;
 182         }
 183         prng_tdes_add_entropy();
 184         prng_data->prngws.reseed_counter = 0;
 185 }
 186
 187
 188 static int __init prng_tdes_instantiate(void)
 189 {
 190         int datalen;
 191
 192         pr_debug("prng runs in TDES mode with "
 193                  "chunksize=%d and reseed_limit=%u\n",
 194                  prng_chunk_size, prng_reseed_limit);
 195
 196         /* memory allocation, prng_data struct init, mutex init */
 197         datalen = sizeof(struct prng_data_s) + prng_chunk_size;
 198         prng_data = kzalloc(datalen, GFP_KERNEL);
 199         if (!prng_data) {
 200                 prng_errorflag = PRNG_INSTANTIATE_FAILED;
 201                 return -ENOMEM;
 202         }
 203         mutex_init(&prng_data->mutex);
 204         prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
 205         memcpy(prng_data->prngws.parm_block, initial_parm_block, 32);
 206
 207         /* initialize the PRNG, add 128 bits of entropy */
 208         prng_tdes_seed(16);
 209
 210         return 0;
 211 }
 212
 213
 214 static void prng_tdes_deinstantiate(void)
 215 {
 216         pr_debug("The prng module stopped "
 217                  "after running in triple DES mode\n");
 218         kzfree(prng_data);
 219 }
 220
 221
 222 /*** sha512 functions ***/
 223
 224 static int __init prng_sha512_selftest(void)
 225 {
 226         /* NIST DRBG testvector for Hash Drbg, Sha-512, Count #0 */
 227         static const u8 seed[] __initconst = {
 228                 0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a,
 229                 0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22,
 230                 0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b,
 231                 0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c,
 232                 0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa,
 233                 0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25 };
 234         static const u8 V0[] __initconst = {
 235                 0x00, 0xad, 0xe3, 0x6f, 0x9a, 0x01, 0xc7, 0x76,
 236                 0x61, 0x34, 0x35, 0xf5, 0x4e, 0x24, 0x74, 0x22,
 237                 0x21, 0x9a, 0x29, 0x89, 0xc7, 0x93, 0x2e, 0x60,
 238                 0x1e, 0xe8, 0x14, 0x24, 0x8d, 0xd5, 0x03, 0xf1,
 239                 0x65, 0x5d, 0x08, 0x22, 0x72, 0xd5, 0xad, 0x95,
 240                 0xe1, 0x23, 0x1e, 0x8a, 0xa7, 0x13, 0xd9, 0x2b,
 241                 0x5e, 0xbc, 0xbb, 0x80, 0xab, 0x8d, 0xe5, 0x79,
 242                 0xab, 0x5b, 0x47, 0x4e, 0xdd, 0xee, 0x6b, 0x03,
 243                 0x8f, 0x0f, 0x5c, 0x5e, 0xa9, 0x1a, 0x83, 0xdd,
 244                 0xd3, 0x88, 0xb2, 0x75, 0x4b, 0xce, 0x83, 0x36,
 245                 0x57, 0x4b, 0xf1, 0x5c, 0xca, 0x7e, 0x09, 0xc0,
 246                 0xd3, 0x89, 0xc6, 0xe0, 0xda, 0xc4, 0x81, 0x7e,
 247                 0x5b, 0xf9, 0xe1, 0x01, 0xc1, 0x92, 0x05, 0xea,
 248                 0xf5, 0x2f, 0xc6, 0xc6, 0xc7, 0x8f, 0xbc, 0xf4 };
 249         static const u8 C0[] __initconst = {
 250                 0x00, 0xf4, 0xa3, 0xe5, 0xa0, 0x72, 0x63, 0x95,
 251                 0xc6, 0x4f, 0x48, 0xd0, 0x8b, 0x5b, 0x5f, 0x8e,
 252                 0x6b, 0x96, 0x1f, 0x16, 0xed, 0xbc, 0x66, 0x94,
 253                 0x45, 0x31, 0xd7, 0x47, 0x73, 0x22, 0xa5, 0x86,
 254                 0xce, 0xc0, 0x4c, 0xac, 0x63, 0xb8, 0x39, 0x50,
 255                 0xbf, 0xe6, 0x59, 0x6c, 0x38, 0x58, 0x99, 0x1f,
 256                 0x27, 0xa7, 0x9d, 0x71, 0x2a, 0xb3, 0x7b, 0xf9,
 257                 0xfb, 0x17, 0x86, 0xaa, 0x99, 0x81, 0xaa, 0x43,
 258                 0xe4, 0x37, 0xd3, 0x1e, 0x6e, 0xe5, 0xe6, 0xee,
 259                 0xc2, 0xed, 0x95, 0x4f, 0x53, 0x0e, 0x46, 0x8a,
 260                 0xcc, 0x45, 0xa5, 0xdb, 0x69, 0x0d, 0x81, 0xc9,
 261                 0x32, 0x92, 0xbc, 0x8f, 0x33, 0xe6, 0xf6, 0x09,
 262                 0x7c, 0x8e, 0x05, 0x19, 0x0d, 0xf1, 0xb6, 0xcc,
 263                 0xf3, 0x02, 0x21, 0x90, 0x25, 0xec, 0xed, 0x0e };
 264         static const u8 random[] __initconst = {
 265                 0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57,
 266                 0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6,
 267                 0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d,
 268                 0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf,
 269                 0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26,
 270                 0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64,
 271                 0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55,
 272                 0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a,
 273                 0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78,
 274                 0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e,
 275                 0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb,
 276                 0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30,
 277                 0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19,
 278                 0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f,
 279                 0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d,
 280                 0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a,
 281                 0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2,
 282                 0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd,
 283                 0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd,
 284                 0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2,
 285                 0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b,
 286                 0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1,
 287                 0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99,
 288                 0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e,
 289                 0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3,
 290                 0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67,
 291                 0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3,
 292                 0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d,
 293                 0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b,
 294                 0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13,
 295                 0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c,
 296                 0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2 };
 297
 298         u8 buf[sizeof(random)];
 299         struct ppno_ws_s ws;
 300
 301         memset(&ws, 0, sizeof(ws));
 302
 303         /* initial seed */
 304         cpacf_ppno(CPACF_PPNO_SHA512_DRNG_SEED,
 305                    &ws, NULL, 0, seed, sizeof(seed));
 306
 307         /* check working states V and C */
 308         if (memcmp(ws.V, V0, sizeof(V0)) != 0
 309             || memcmp(ws.C, C0, sizeof(C0)) != 0) {
 310                 pr_err("The prng self test state test "
 311                        "for the SHA-512 mode failed\n");
 312                 prng_errorflag = PRNG_SELFTEST_FAILED;
 313                 return -EIO;
 314         }
 315
 316         /* generate random bytes */
 317         cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
 318                    &ws, buf, sizeof(buf), NULL, 0);
 319         cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
 320                    &ws, buf, sizeof(buf), NULL, 0);
 321
 322         /* check against expected data */
 323         if (memcmp(buf, random, sizeof(random)) != 0) {
 324                 pr_err("The prng self test data test "
 325                        "for the SHA-512 mode failed\n");
 326                 prng_errorflag = PRNG_SELFTEST_FAILED;
 327                 return -EIO;
 328         }
 329
 330         return 0;
 331 }
 332
 333
 334 static int __init prng_sha512_instantiate(void)
 335 {
 336         int ret, datalen;
 337         u8 seed[64];
 338
 339         pr_debug("prng runs in SHA-512 mode "
 340                  "with chunksize=%d and reseed_limit=%u\n",
 341                  prng_chunk_size, prng_reseed_limit);
 342
 343         /* memory allocation, prng_data struct init, mutex init */
 344         datalen = sizeof(struct prng_data_s) + prng_chunk_size;
 345         if (fips_enabled)
 346                 datalen += prng_chunk_size;
 347         prng_data = kzalloc(datalen, GFP_KERNEL);
 348         if (!prng_data) {
 349                 prng_errorflag = PRNG_INSTANTIATE_FAILED;
 350                 return -ENOMEM;
 351         }
 352         mutex_init(&prng_data->mutex);
 353         prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
 354
 355         /* selftest */
 356         ret = prng_sha512_selftest();
 357         if (ret)
 358                 goto outfree;
 359
 360         /* generate initial seed bytestring, first 48 bytes of entropy */
 361         ret = generate_entropy(seed, 48);
 362         if (ret != 48)
 363                 goto outfree;
 364         /* followed by 16 bytes of unique nonce */
 365         get_tod_clock_ext(seed + 48);
 366
 367         /* initial seed of the ppno drng */
 368         cpacf_ppno(CPACF_PPNO_SHA512_DRNG_SEED,
 369                    &prng_data->ppnows, NULL, 0, seed, sizeof(seed));
 370
 371         /* if fips mode is enabled, generate a first block of random
 372            bytes for the FIPS 140-2 Conditional Self Test */
 373         if (fips_enabled) {
 374                 prng_data->prev = prng_data->buf + prng_chunk_size;
 375                 cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
 376                            &prng_data->ppnows,
 377                            prng_data->prev, prng_chunk_size, NULL, 0);
 378         }
 379
 380         return 0;
 381
 382 outfree:
 383         kfree(prng_data);
 384         return ret;
 385 }
 386
 387
 388 static void prng_sha512_deinstantiate(void)
 389 {
 390         pr_debug("The prng module stopped after running in SHA-512 mode\n");
 391         kzfree(prng_data);
 392 }
 393
 394
 395 static int prng_sha512_reseed(void)
 396 {
 397         int ret;
 398         u8 seed[32];
 399
 400         /* generate 32 bytes of fresh entropy */
 401         ret = generate_entropy(seed, sizeof(seed));
 402         if (ret != sizeof(seed))
 403                 return ret;
 404
 405         /* do a reseed of the ppno drng with this bytestring */
 406         cpacf_ppno(CPACF_PPNO_SHA512_DRNG_SEED,
 407                    &prng_data->ppnows, NULL, 0, seed, sizeof(seed));
 408
 409         return 0;
 410 }
 411
 412
 413 static int prng_sha512_generate(u8 *buf, size_t nbytes)
 414 {
 415         int ret;
 416
 417         /* reseed needed ? */
 418         if (prng_data->ppnows.reseed_counter > prng_reseed_limit) {
 419                 ret = prng_sha512_reseed();
 420                 if (ret)
 421                         return ret;
 422         }
 423
 424         /* PPNO generate */
 425         cpacf_ppno(CPACF_PPNO_SHA512_DRNG_GEN,
 426                    &prng_data->ppnows, buf, nbytes, NULL, 0);
 427
 428         /* FIPS 140-2 Conditional Self Test */
 429         if (fips_enabled) {
 430                 if (!memcmp(prng_data->prev, buf, nbytes)) {
 431                         prng_errorflag = PRNG_GEN_FAILED;
 432                         return -EILSEQ;
 433                 }
 434                 memcpy(prng_data->prev, buf, nbytes);
 435         }
 436
 437         return nbytes;
 438 }
 439
 440
 441 /*** file io functions ***/
 442
 443 static int prng_open(struct inode *inode, struct file *file)
 444 {
 445         return nonseekable_open(inode, file);
 446 }
 447
 448
 449 static ssize_t prng_tdes_read(struct file *file, char __user *ubuf,
 450                               size_t nbytes, loff_t *ppos)
 451 {
 452         int chunk, n, ret = 0;
 453
 454         /* lock prng_data struct */
 455         if (mutex_lock_interruptible(&prng_data->mutex))
 456                 return -ERESTARTSYS;
 457
 458         while (nbytes) {
 459                 if (need_resched()) {
 460                         if (signal_pending(current)) {
 461                                 if (ret == 0)
 462                                         ret = -ERESTARTSYS;
 463                                 break;
 464                         }
 465                         /* give mutex free before calling schedule() */
 466                         mutex_unlock(&prng_data->mutex);
 467                         schedule();
 468                         /* occopy mutex again */
 469                         if (mutex_lock_interruptible(&prng_data->mutex)) {
 470                                 if (ret == 0)
 471                                         ret = -ERESTARTSYS;
 472                                 return ret;
 473                         }
 474                 }
 475
 476                 /*
 477                  * we lose some random bytes if an attacker issues
 478                  * reads < 8 bytes, but we don't care
 479                  */
 480                 chunk = min_t(int, nbytes, prng_chunk_size);
 481
 482                 /* PRNG only likes multiples of 8 bytes */
 483                 n = (chunk + 7) & -8;
 484
 485                 if (prng_data->prngws.reseed_counter > prng_reseed_limit)
 486                         prng_tdes_seed(8);
 487
 488                 /* if the CPU supports PRNG stckf is present too */
 489                 *((unsigned long long *)prng_data->buf) = get_tod_clock_fast();
 490
 491                 /*
 492                  * Beside the STCKF the input for the TDES-EDE is the output
 493                  * of the last operation. We differ here from X9.17 since we
 494                  * only store one timestamp into the buffer. Padding the whole
 495                  * buffer with timestamps does not improve security, since
 496                  * successive stckf have nearly constant offsets.
 497                  * If an attacker knows the first timestamp it would be
 498                  * trivial to guess the additional values. One timestamp
 499                  * is therefore enough and still guarantees unique input values.
 500                  *
 501                  * Note: you can still get strict X9.17 conformity by setting
 502                  * prng_chunk_size to 8 bytes.
 503                  */
 504                 cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
 505                           prng_data->buf, prng_data->buf, n);
 506
 507                 prng_data->prngws.byte_counter += n;
 508                 prng_data->prngws.reseed_counter += n;
 509
 510                 if (copy_to_user(ubuf, prng_data->buf, chunk)) {
 511                         ret = -EFAULT;
 512                         break;
 513                 }
 514
 515                 nbytes -= chunk;
 516                 ret += chunk;
 517                 ubuf += chunk;
 518         }
 519
 520         /* unlock prng_data struct */
 521         mutex_unlock(&prng_data->mutex);
 522
 523         return ret;
 524 }
 525
 526
 527 static ssize_t prng_sha512_read(struct file *file, char __user *ubuf,
 528                                 size_t nbytes, loff_t *ppos)
 529 {
 530         int n, ret = 0;
 531         u8 *p;
 532
 533         /* if errorflag is set do nothing and return 'broken pipe' */
 534         if (prng_errorflag)
 535                 return -EPIPE;
 536
 537         /* lock prng_data struct */
 538         if (mutex_lock_interruptible(&prng_data->mutex))
 539                 return -ERESTARTSYS;
 540
 541         while (nbytes) {
 542                 if (need_resched()) {
 543                         if (signal_pending(current)) {
 544                                 if (ret == 0)
 545                                         ret = -ERESTARTSYS;
 546                                 break;
 547                         }
 548                         /* give mutex free before calling schedule() */
 549                         mutex_unlock(&prng_data->mutex);
 550                         schedule();
 551                         /* occopy mutex again */
 552                         if (mutex_lock_interruptible(&prng_data->mutex)) {
 553                                 if (ret == 0)
 554                                         ret = -ERESTARTSYS;
 555                                 return ret;
 556                         }
 557                 }
 558                 if (prng_data->rest) {
 559                         /* push left over random bytes from the previous read */
 560                         p = prng_data->buf + prng_chunk_size - prng_data->rest;
 561                         n = (nbytes < prng_data->rest) ?
 562                                 nbytes : prng_data->rest;
 563                         prng_data->rest -= n;
 564                 } else {
 565                         /* generate one chunk of random bytes into read buf */
 566                         p = prng_data->buf;
 567                         n = prng_sha512_generate(p, prng_chunk_size);
 568                         if (n < 0) {
 569                                 ret = n;
 570                                 break;
 571                         }
 572                         if (nbytes < prng_chunk_size) {
 573                                 n = nbytes;
 574                                 prng_data->rest = prng_chunk_size - n;
 575                         } else {
 576                                 n = prng_chunk_size;
 577                                 prng_data->rest = 0;
 578                         }
 579                 }
 580                 if (copy_to_user(ubuf, p, n)) {
 581                         ret = -EFAULT;
 582                         break;
 583                 }
 584                 ubuf += n;
 585                 nbytes -= n;
 586                 ret += n;
 587         }
 588
 589         /* unlock prng_data struct */
 590         mutex_unlock(&prng_data->mutex);
 591
 592         return ret;
 593 }
 594
 595
 596 /*** sysfs stuff ***/
 597
 598 static const struct file_operations prng_sha512_fops = {
 599         .owner          = THIS_MODULE,
 600         .open           = &prng_open,
 601         .release        = NULL,
 602         .read           = &prng_sha512_read,
 603         .llseek         = noop_llseek,
 604 };
 605 static const struct file_operations prng_tdes_fops = {
 606         .owner          = THIS_MODULE,
 607         .open           = &prng_open,
 608         .release        = NULL,
 609         .read           = &prng_tdes_read,
 610         .llseek         = noop_llseek,
 611 };
 612
 613 static struct miscdevice prng_sha512_dev = {
 614         .name   = "prandom",
 615         .minor  = MISC_DYNAMIC_MINOR,
 616         .mode   = 0644,
 617         .fops   = &prng_sha512_fops,
 618 };
 619 static struct miscdevice prng_tdes_dev = {
 620         .name   = "prandom",
 621         .minor  = MISC_DYNAMIC_MINOR,
 622         .mode   = 0644,
 623         .fops   = &prng_tdes_fops,
 624 };
 625
 626
 627 /* chunksize attribute (ro) */
 628 static ssize_t prng_chunksize_show(struct device *dev,
 629                                    struct device_attribute *attr,
 630                                    char *buf)
 631 {
 632         return snprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
 633 }
 634 static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);
 635
 636 /* counter attribute (ro) */
 637 static ssize_t prng_counter_show(struct device *dev,
 638                                  struct device_attribute *attr,
 639                                  char *buf)
 640 {
 641         u64 counter;
 642
 643         if (mutex_lock_interruptible(&prng_data->mutex))
 644                 return -ERESTARTSYS;
 645         if (prng_mode == PRNG_MODE_SHA512)
 646                 counter = prng_data->ppnows.stream_bytes;
 647         else
 648                 counter = prng_data->prngws.byte_counter;
 649         mutex_unlock(&prng_data->mutex);
 650
 651         return snprintf(buf, PAGE_SIZE, "%llu\n", counter);
 652 }
 653 static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);
 654
 655 /* errorflag attribute (ro) */
 656 static ssize_t prng_errorflag_show(struct device *dev,
 657                                    struct device_attribute *attr,
 658                                    char *buf)
 659 {
 660         return snprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
 661 }
 662 static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);
 663
 664 /* mode attribute (ro) */
 665 static ssize_t prng_mode_show(struct device *dev,
 666                               struct device_attribute *attr,
 667                               char *buf)
 668 {
 669         if (prng_mode == PRNG_MODE_TDES)
 670                 return snprintf(buf, PAGE_SIZE, "TDES\n");
 671         else
 672                 return snprintf(buf, PAGE_SIZE, "SHA512\n");
 673 }
 674 static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);
 675
 676 /* reseed attribute (w) */
 677 static ssize_t prng_reseed_store(struct device *dev,
 678                                  struct device_attribute *attr,
 679                                  const char *buf, size_t count)
 680 {
 681         if (mutex_lock_interruptible(&prng_data->mutex))
 682                 return -ERESTARTSYS;
 683         prng_sha512_reseed();
 684         mutex_unlock(&prng_data->mutex);
 685
 686         return count;
 687 }
 688 static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store);
 689
 690 /* reseed limit attribute (rw) */
 691 static ssize_t prng_reseed_limit_show(struct device *dev,
 692                                       struct device_attribute *attr,
 693                                       char *buf)
 694 {
 695         return snprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
 696 }
 697 static ssize_t prng_reseed_limit_store(struct device *dev,
 698                                        struct device_attribute *attr,
 699                                        const char *buf, size_t count)
 700 {
 701         unsigned limit;
 702
 703         if (sscanf(buf, "%u\n", &limit) != 1)
 704                 return -EINVAL;
 705
 706         if (prng_mode == PRNG_MODE_SHA512) {
 707                 if (limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
 708                         return -EINVAL;
 709         } else {
 710                 if (limit < PRNG_RESEED_LIMIT_TDES_LOWER)
 711                         return -EINVAL;
 712         }
 713
 714         prng_reseed_limit = limit;
 715
 716         return count;
 717 }
 718 static DEVICE_ATTR(reseed_limit, 0644,
 719                    prng_reseed_limit_show, prng_reseed_limit_store);
 720
 721 /* strength attribute (ro) */
 722 static ssize_t prng_strength_show(struct device *dev,
 723                                   struct device_attribute *attr,
 724                                   char *buf)
 725 {
 726         return snprintf(buf, PAGE_SIZE, "256\n");
 727 }
 728 static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);
 729
 730 static struct attribute *prng_sha512_dev_attrs[] = {
 731         &dev_attr_errorflag.attr,
 732         &dev_attr_chunksize.attr,
 733         &dev_attr_byte_counter.attr,
 734         &dev_attr_mode.attr,
 735         &dev_attr_reseed.attr,
 736         &dev_attr_reseed_limit.attr,
 737         &dev_attr_strength.attr,
 738         NULL
 739 };
 740 static struct attribute *prng_tdes_dev_attrs[] = {
 741         &dev_attr_chunksize.attr,
 742         &dev_attr_byte_counter.attr,
 743         &dev_attr_mode.attr,
 744         NULL
 745 };
 746
 747 static struct attribute_group prng_sha512_dev_attr_group = {
 748         .attrs = prng_sha512_dev_attrs
 749 };
 750 static struct attribute_group prng_tdes_dev_attr_group = {
 751         .attrs = prng_tdes_dev_attrs
 752 };
 753
 754
 755 /*** module init and exit ***/
 756
 757 static int __init prng_init(void)
 758 {
 759         int ret;
 760
 761         /* check if the CPU has a PRNG */
 762         if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG))
 763                 return -EOPNOTSUPP;
 764
 765         /* choose prng mode */
 766         if (prng_mode != PRNG_MODE_TDES) {
 767                 /* check for MSA5 support for PPNO operations */
 768                 if (!cpacf_query_func(CPACF_PPNO, CPACF_PPNO_SHA512_DRNG_GEN)) {
 769                         if (prng_mode == PRNG_MODE_SHA512) {
 770                                 pr_err("The prng module cannot "
 771                                        "start in SHA-512 mode\n");
 772                                 return -EOPNOTSUPP;
 773                         }
 774                         prng_mode = PRNG_MODE_TDES;
 775                 } else
 776                         prng_mode = PRNG_MODE_SHA512;
 777         }
 778
 779         if (prng_mode == PRNG_MODE_SHA512) {
 780
 781                 /* SHA512 mode */
 782
 783                 if (prng_chunk_size < PRNG_CHUNKSIZE_SHA512_MIN
 784                     || prng_chunk_size > PRNG_CHUNKSIZE_SHA512_MAX)
 785                         return -EINVAL;
 786                 prng_chunk_size = (prng_chunk_size + 0x3f) & ~0x3f;
 787
 788                 if (prng_reseed_limit == 0)
 789                         prng_reseed_limit = PRNG_RESEED_LIMIT_SHA512;
 790                 else if (prng_reseed_limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
 791                         return -EINVAL;
 792
 793                 ret = prng_sha512_instantiate();
 794                 if (ret)
 795                         goto out;
 796
 797                 ret = misc_register(&prng_sha512_dev);
 798                 if (ret) {
 799                         prng_sha512_deinstantiate();
 800                         goto out;
 801                 }
 802                 ret = sysfs_create_group(&prng_sha512_dev.this_device->kobj,
 803                                          &prng_sha512_dev_attr_group);
 804                 if (ret) {
 805                         misc_deregister(&prng_sha512_dev);
 806                         prng_sha512_deinstantiate();
 807                         goto out;
 808                 }
 809
 810         } else {
 811
 812                 /* TDES mode */
 813
 814                 if (prng_chunk_size < PRNG_CHUNKSIZE_TDES_MIN
 815                     || prng_chunk_size > PRNG_CHUNKSIZE_TDES_MAX)
 816                         return -EINVAL;
 817                 prng_chunk_size = (prng_chunk_size + 0x07) & ~0x07;
 818
 819                 if (prng_reseed_limit == 0)
 820                         prng_reseed_limit = PRNG_RESEED_LIMIT_TDES;
 821                 else if (prng_reseed_limit < PRNG_RESEED_LIMIT_TDES_LOWER)
 822                         return -EINVAL;
 823
 824                 ret = prng_tdes_instantiate();
 825                 if (ret)
 826                         goto out;
 827
 828                 ret = misc_register(&prng_tdes_dev);
 829                 if (ret) {
 830                         prng_tdes_deinstantiate();
 831                         goto out;
 832                 }
 833                 ret = sysfs_create_group(&prng_tdes_dev.this_device->kobj,
 834                                          &prng_tdes_dev_attr_group);
 835                 if (ret) {
 836                         misc_deregister(&prng_tdes_dev);
 837                         prng_tdes_deinstantiate();
 838                         goto out;
 839                 }
 840
 841         }
 842
 843 out:
 844         return ret;
 845 }
 846
 847
 848 static void __exit prng_exit(void)
 849 {
 850         if (prng_mode == PRNG_MODE_SHA512) {
 851                 sysfs_remove_group(&prng_sha512_dev.this_device->kobj,
 852                                    &prng_sha512_dev_attr_group);
 853                 misc_deregister(&prng_sha512_dev);
 854                 prng_sha512_deinstantiate();
 855         } else {
 856                 sysfs_remove_group(&prng_tdes_dev.this_device->kobj,
 857                                    &prng_tdes_dev_attr_group);
 858                 misc_deregister(&prng_tdes_dev);
 859                 prng_tdes_deinstantiate();
 860         }
 861 }
 862
 863 module_cpu_feature_match(MSA, prng_init);
 864 module_exit(prng_exit);