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linux/arch/s390/crypto/prng.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2006, 2015
* Author(s): Jan Glauber <jan.glauber@de.ibm.com>
* Harald Freudenberger <freude@de.ibm.com>
* Driver for the s390 pseudo random number generator
*/
#define KMSG_COMPONENT "prng"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/fs.h>
#include <linux/fips.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/cpufeature.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <asm/debug.h>
#include <linux/uaccess.h>
#include <asm/timex.h>
#include <asm/cpacf.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("IBM Corporation");
MODULE_DESCRIPTION("s390 PRNG interface");
#define PRNG_MODE_AUTO 0
#define PRNG_MODE_TDES 1
#define PRNG_MODE_SHA512 2
static unsigned int prng_mode = PRNG_MODE_AUTO;
module_param_named(mode, prng_mode, int, 0);
MODULE_PARM_DESC(prng_mode, "PRNG mode: 0 - auto, 1 - TDES, 2 - SHA512");
#define PRNG_CHUNKSIZE_TDES_MIN 8
#define PRNG_CHUNKSIZE_TDES_MAX (64*1024)
#define PRNG_CHUNKSIZE_SHA512_MIN 64
#define PRNG_CHUNKSIZE_SHA512_MAX (64*1024)
static unsigned int prng_chunk_size = 256;
module_param_named(chunksize, prng_chunk_size, int, 0);
MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes");
#define PRNG_RESEED_LIMIT_TDES 4096
#define PRNG_RESEED_LIMIT_TDES_LOWER 4096
#define PRNG_RESEED_LIMIT_SHA512 100000
#define PRNG_RESEED_LIMIT_SHA512_LOWER 10000
static unsigned int prng_reseed_limit;
module_param_named(reseed_limit, prng_reseed_limit, int, 0);
MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit");
static bool trng_available;
/*
* Any one who considers arithmetical methods of producing random digits is,
* of course, in a state of sin. -- John von Neumann
*/
static int prng_errorflag;
#define PRNG_GEN_ENTROPY_FAILED 1
#define PRNG_SELFTEST_FAILED 2
#define PRNG_INSTANTIATE_FAILED 3
#define PRNG_SEED_FAILED 4
#define PRNG_RESEED_FAILED 5
#define PRNG_GEN_FAILED 6
struct prng_ws_s {
u8 parm_block[32];
u32 reseed_counter;
u64 byte_counter;
};
struct prno_ws_s {
u32 res;
u32 reseed_counter;
u64 stream_bytes;
u8 V[112];
u8 C[112];
};
struct prng_data_s {
struct mutex mutex;
union {
struct prng_ws_s prngws;
struct prno_ws_s prnows;
};
u8 *buf;
u32 rest;
u8 *prev;
};
static struct prng_data_s *prng_data;
/* initial parameter block for tdes mode, copied from libica */
static const u8 initial_parm_block[32] __initconst = {
0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 };
/*** helper functions ***/
/*
* generate_entropy:
* This function fills a given buffer with random bytes. The entropy within
* the random bytes given back is assumed to have at least 50% - meaning
* a 64 bytes buffer has at least 64 * 8 / 2 = 256 bits of entropy.
* Within the function the entropy generation is done in junks of 64 bytes.
* So the caller should also ask for buffer fill in multiples of 64 bytes.
* The generation of the entropy is based on the assumption that every stckf()
* invocation produces 0.5 bits of entropy. To accumulate 256 bits of entropy
* at least 512 stckf() values are needed. The entropy relevant part of the
* stckf value is bit 51 (counting starts at the left with bit nr 0) so
* here we use the lower 4 bytes and exor the values into 2k of bufferspace.
* To be on the save side, if there is ever a problem with stckf() the
* other half of the page buffer is filled with bytes from urandom via
* get_random_bytes(), so this function consumes 2k of urandom for each
* requested 64 bytes output data. Finally the buffer page is condensed into
* a 64 byte value by hashing with a SHA512 hash.
*/
static int generate_entropy(u8 *ebuf, size_t nbytes)
{
int n, ret = 0;
u8 *pg, pblock[80] = {
/* 8 x 64 bit init values */
0x6A, 0x09, 0xE6, 0x67, 0xF3, 0xBC, 0xC9, 0x08,
0xBB, 0x67, 0xAE, 0x85, 0x84, 0xCA, 0xA7, 0x3B,
0x3C, 0x6E, 0xF3, 0x72, 0xFE, 0x94, 0xF8, 0x2B,
0xA5, 0x4F, 0xF5, 0x3A, 0x5F, 0x1D, 0x36, 0xF1,
0x51, 0x0E, 0x52, 0x7F, 0xAD, 0xE6, 0x82, 0xD1,
0x9B, 0x05, 0x68, 0x8C, 0x2B, 0x3E, 0x6C, 0x1F,
0x1F, 0x83, 0xD9, 0xAB, 0xFB, 0x41, 0xBD, 0x6B,
0x5B, 0xE0, 0xCD, 0x19, 0x13, 0x7E, 0x21, 0x79,
/* 128 bit counter total message bit length */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00 };
/* allocate one page stckf buffer */
pg = (u8 *) __get_free_page(GFP_KERNEL);
if (!pg) {
prng_errorflag = PRNG_GEN_ENTROPY_FAILED;
return -ENOMEM;
}
/* fill the ebuf in chunks of 64 byte each */
while (nbytes) {
/* fill lower 2k with urandom bytes */
get_random_bytes(pg, PAGE_SIZE / 2);
/* exor upper 2k with 512 stckf values, offset 4 bytes each */
for (n = 0; n < 512; n++) {
int offset = (PAGE_SIZE / 2) + (n * 4) - 4;
u64 *p = (u64 *)(pg + offset);
*p ^= get_tod_clock_fast();
}
/* hash over the filled page */
cpacf_klmd(CPACF_KLMD_SHA_512, pblock, pg, PAGE_SIZE);
n = (nbytes < 64) ? nbytes : 64;
memcpy(ebuf, pblock, n);
ret += n;
ebuf += n;
nbytes -= n;
}
memzero_explicit(pblock, sizeof(pblock));
memzero_explicit(pg, PAGE_SIZE);
free_page((unsigned long)pg);
return ret;
}
/*** tdes functions ***/
static void prng_tdes_add_entropy(void)
{
__u64 entropy[4];
unsigned int i;
for (i = 0; i < 16; i++) {
cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
(char *) entropy, (char *) entropy,
sizeof(entropy));
memcpy(prng_data->prngws.parm_block, entropy, sizeof(entropy));
}
}
static void prng_tdes_seed(int nbytes)
{
char buf[16];
int i = 0;
BUG_ON(nbytes > sizeof(buf));
get_random_bytes(buf, nbytes);
/* Add the entropy */
while (nbytes >= 8) {
*((__u64 *)prng_data->prngws.parm_block) ^= *((__u64 *)(buf+i));
prng_tdes_add_entropy();
i += 8;
nbytes -= 8;
}
prng_tdes_add_entropy();
prng_data->prngws.reseed_counter = 0;
}
static int __init prng_tdes_instantiate(void)
{
int datalen;
pr_debug("prng runs in TDES mode with "
"chunksize=%d and reseed_limit=%u\n",
prng_chunk_size, prng_reseed_limit);
/* memory allocation, prng_data struct init, mutex init */
datalen = sizeof(struct prng_data_s) + prng_chunk_size;
prng_data = kzalloc(datalen, GFP_KERNEL);
if (!prng_data) {
prng_errorflag = PRNG_INSTANTIATE_FAILED;
return -ENOMEM;
}
mutex_init(&prng_data->mutex);
prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
memcpy(prng_data->prngws.parm_block, initial_parm_block, 32);
/* initialize the PRNG, add 128 bits of entropy */
prng_tdes_seed(16);
return 0;
}
static void prng_tdes_deinstantiate(void)
{
pr_debug("The prng module stopped "
"after running in triple DES mode\n");
kzfree(prng_data);
}
/*** sha512 functions ***/
static int __init prng_sha512_selftest(void)
{
/* NIST DRBG testvector for Hash Drbg, Sha-512, Count #0 */
static const u8 seed[] __initconst = {
0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a,
0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22,
0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b,
0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c,
0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa,
0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25 };
static const u8 V0[] __initconst = {
0x00, 0xad, 0xe3, 0x6f, 0x9a, 0x01, 0xc7, 0x76,
0x61, 0x34, 0x35, 0xf5, 0x4e, 0x24, 0x74, 0x22,
0x21, 0x9a, 0x29, 0x89, 0xc7, 0x93, 0x2e, 0x60,
0x1e, 0xe8, 0x14, 0x24, 0x8d, 0xd5, 0x03, 0xf1,
0x65, 0x5d, 0x08, 0x22, 0x72, 0xd5, 0xad, 0x95,
0xe1, 0x23, 0x1e, 0x8a, 0xa7, 0x13, 0xd9, 0x2b,
0x5e, 0xbc, 0xbb, 0x80, 0xab, 0x8d, 0xe5, 0x79,
0xab, 0x5b, 0x47, 0x4e, 0xdd, 0xee, 0x6b, 0x03,
0x8f, 0x0f, 0x5c, 0x5e, 0xa9, 0x1a, 0x83, 0xdd,
0xd3, 0x88, 0xb2, 0x75, 0x4b, 0xce, 0x83, 0x36,
0x57, 0x4b, 0xf1, 0x5c, 0xca, 0x7e, 0x09, 0xc0,
0xd3, 0x89, 0xc6, 0xe0, 0xda, 0xc4, 0x81, 0x7e,
0x5b, 0xf9, 0xe1, 0x01, 0xc1, 0x92, 0x05, 0xea,
0xf5, 0x2f, 0xc6, 0xc6, 0xc7, 0x8f, 0xbc, 0xf4 };
static const u8 C0[] __initconst = {
0x00, 0xf4, 0xa3, 0xe5, 0xa0, 0x72, 0x63, 0x95,
0xc6, 0x4f, 0x48, 0xd0, 0x8b, 0x5b, 0x5f, 0x8e,
0x6b, 0x96, 0x1f, 0x16, 0xed, 0xbc, 0x66, 0x94,
0x45, 0x31, 0xd7, 0x47, 0x73, 0x22, 0xa5, 0x86,
0xce, 0xc0, 0x4c, 0xac, 0x63, 0xb8, 0x39, 0x50,
0xbf, 0xe6, 0x59, 0x6c, 0x38, 0x58, 0x99, 0x1f,
0x27, 0xa7, 0x9d, 0x71, 0x2a, 0xb3, 0x7b, 0xf9,
0xfb, 0x17, 0x86, 0xaa, 0x99, 0x81, 0xaa, 0x43,
0xe4, 0x37, 0xd3, 0x1e, 0x6e, 0xe5, 0xe6, 0xee,
0xc2, 0xed, 0x95, 0x4f, 0x53, 0x0e, 0x46, 0x8a,
0xcc, 0x45, 0xa5, 0xdb, 0x69, 0x0d, 0x81, 0xc9,
0x32, 0x92, 0xbc, 0x8f, 0x33, 0xe6, 0xf6, 0x09,
0x7c, 0x8e, 0x05, 0x19, 0x0d, 0xf1, 0xb6, 0xcc,
0xf3, 0x02, 0x21, 0x90, 0x25, 0xec, 0xed, 0x0e };
static const u8 random[] __initconst = {
0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57,
0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6,
0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d,
0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf,
0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26,
0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64,
0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55,
0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a,
0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78,
0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e,
0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb,
0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30,
0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19,
0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f,
0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d,
0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a,
0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2,
0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd,
0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd,
0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2,
0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b,
0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1,
0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99,
0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e,
0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3,
0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67,
0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3,
0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d,
0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b,
0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13,
0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c,
0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2 };
u8 buf[sizeof(random)];
struct prno_ws_s ws;
memset(&ws, 0, sizeof(ws));
/* initial seed */
cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
&ws, NULL, 0, seed, sizeof(seed));
/* check working states V and C */
if (memcmp(ws.V, V0, sizeof(V0)) != 0
|| memcmp(ws.C, C0, sizeof(C0)) != 0) {
pr_err("The prng self test state test "
"for the SHA-512 mode failed\n");
prng_errorflag = PRNG_SELFTEST_FAILED;
return -EIO;
}
/* generate random bytes */
cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
&ws, buf, sizeof(buf), NULL, 0);
cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
&ws, buf, sizeof(buf), NULL, 0);
/* check against expected data */
if (memcmp(buf, random, sizeof(random)) != 0) {
pr_err("The prng self test data test "
"for the SHA-512 mode failed\n");
prng_errorflag = PRNG_SELFTEST_FAILED;
return -EIO;
}
return 0;
}
static int __init prng_sha512_instantiate(void)
{
int ret, datalen, seedlen;
u8 seed[128 + 16];
pr_debug("prng runs in SHA-512 mode "
"with chunksize=%d and reseed_limit=%u\n",
prng_chunk_size, prng_reseed_limit);
/* memory allocation, prng_data struct init, mutex init */
datalen = sizeof(struct prng_data_s) + prng_chunk_size;
if (fips_enabled)
datalen += prng_chunk_size;
prng_data = kzalloc(datalen, GFP_KERNEL);
if (!prng_data) {
prng_errorflag = PRNG_INSTANTIATE_FAILED;
return -ENOMEM;
}
mutex_init(&prng_data->mutex);
prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
/* selftest */
ret = prng_sha512_selftest();
if (ret)
goto outfree;
/* generate initial seed, we need at least 256 + 128 bits entropy. */
if (trng_available) {
/*
* Trng available, so use it. The trng works in chunks of
* 32 bytes and produces 100% entropy. So we pull 64 bytes
* which gives us 512 bits entropy.
*/
seedlen = 2 * 32;
cpacf_trng(NULL, 0, seed, seedlen);
} else {
/*
* No trng available, so use the generate_entropy() function.
* This function works in 64 byte junks and produces
* 50% entropy. So we pull 2*64 bytes which gives us 512 bits
* of entropy.
*/
seedlen = 2 * 64;
ret = generate_entropy(seed, seedlen);
if (ret != seedlen)
goto outfree;
}
/* append the seed by 16 bytes of unique nonce */
get_tod_clock_ext(seed + seedlen);
seedlen += 16;
/* now initial seed of the prno drng */
cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
&prng_data->prnows, NULL, 0, seed, seedlen);
memzero_explicit(seed, sizeof(seed));
/* if fips mode is enabled, generate a first block of random
bytes for the FIPS 140-2 Conditional Self Test */
if (fips_enabled) {
prng_data->prev = prng_data->buf + prng_chunk_size;
cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
&prng_data->prnows,
prng_data->prev, prng_chunk_size, NULL, 0);
}
return 0;
outfree:
kfree(prng_data);
return ret;
}
static void prng_sha512_deinstantiate(void)
{
pr_debug("The prng module stopped after running in SHA-512 mode\n");
kzfree(prng_data);
}
static int prng_sha512_reseed(void)
{
int ret, seedlen;
u8 seed[64];
/* We need at least 256 bits of fresh entropy for reseeding */
if (trng_available) {
/* trng produces 256 bits entropy in 32 bytes */
seedlen = 32;
cpacf_trng(NULL, 0, seed, seedlen);
} else {
/* generate_entropy() produces 256 bits entropy in 64 bytes */
seedlen = 64;
ret = generate_entropy(seed, seedlen);
if (ret != sizeof(seed))
return ret;
}
/* do a reseed of the prno drng with this bytestring */
cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
&prng_data->prnows, NULL, 0, seed, seedlen);
memzero_explicit(seed, sizeof(seed));
return 0;
}
static int prng_sha512_generate(u8 *buf, size_t nbytes)
{
int ret;
/* reseed needed ? */
if (prng_data->prnows.reseed_counter > prng_reseed_limit) {
ret = prng_sha512_reseed();
if (ret)
return ret;
}
/* PRNO generate */
cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
&prng_data->prnows, buf, nbytes, NULL, 0);
/* FIPS 140-2 Conditional Self Test */
if (fips_enabled) {
if (!memcmp(prng_data->prev, buf, nbytes)) {
prng_errorflag = PRNG_GEN_FAILED;
return -EILSEQ;
}
memcpy(prng_data->prev, buf, nbytes);
}
return nbytes;
}
/*** file io functions ***/
static int prng_open(struct inode *inode, struct file *file)
{
return nonseekable_open(inode, file);
}
static ssize_t prng_tdes_read(struct file *file, char __user *ubuf,
size_t nbytes, loff_t *ppos)
{
int chunk, n, ret = 0;
/* lock prng_data struct */
if (mutex_lock_interruptible(&prng_data->mutex))
return -ERESTARTSYS;
while (nbytes) {
if (need_resched()) {
if (signal_pending(current)) {
if (ret == 0)
ret = -ERESTARTSYS;
break;
}
/* give mutex free before calling schedule() */
mutex_unlock(&prng_data->mutex);
schedule();
/* occopy mutex again */
if (mutex_lock_interruptible(&prng_data->mutex)) {
if (ret == 0)
ret = -ERESTARTSYS;
return ret;
}
}
/*
* we lose some random bytes if an attacker issues
* reads < 8 bytes, but we don't care
*/
chunk = min_t(int, nbytes, prng_chunk_size);
/* PRNG only likes multiples of 8 bytes */
n = (chunk + 7) & -8;
if (prng_data->prngws.reseed_counter > prng_reseed_limit)
prng_tdes_seed(8);
/* if the CPU supports PRNG stckf is present too */
*((unsigned long long *)prng_data->buf) = get_tod_clock_fast();
/*
* Beside the STCKF the input for the TDES-EDE is the output
* of the last operation. We differ here from X9.17 since we
* only store one timestamp into the buffer. Padding the whole
* buffer with timestamps does not improve security, since
* successive stckf have nearly constant offsets.
* If an attacker knows the first timestamp it would be
* trivial to guess the additional values. One timestamp
* is therefore enough and still guarantees unique input values.
*
* Note: you can still get strict X9.17 conformity by setting
* prng_chunk_size to 8 bytes.
*/
cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
prng_data->buf, prng_data->buf, n);
prng_data->prngws.byte_counter += n;
prng_data->prngws.reseed_counter += n;
if (copy_to_user(ubuf, prng_data->buf, chunk)) {
ret = -EFAULT;
break;
}
nbytes -= chunk;
ret += chunk;
ubuf += chunk;
}
/* unlock prng_data struct */
mutex_unlock(&prng_data->mutex);
return ret;
}
static ssize_t prng_sha512_read(struct file *file, char __user *ubuf,
size_t nbytes, loff_t *ppos)
{
int n, ret = 0;
u8 *p;
/* if errorflag is set do nothing and return 'broken pipe' */
if (prng_errorflag)
return -EPIPE;
/* lock prng_data struct */
if (mutex_lock_interruptible(&prng_data->mutex))
return -ERESTARTSYS;
while (nbytes) {
if (need_resched()) {
if (signal_pending(current)) {
if (ret == 0)
ret = -ERESTARTSYS;
break;
}
/* give mutex free before calling schedule() */
mutex_unlock(&prng_data->mutex);
schedule();
/* occopy mutex again */
if (mutex_lock_interruptible(&prng_data->mutex)) {
if (ret == 0)
ret = -ERESTARTSYS;
return ret;
}
}
if (prng_data->rest) {
/* push left over random bytes from the previous read */
p = prng_data->buf + prng_chunk_size - prng_data->rest;
n = (nbytes < prng_data->rest) ?
nbytes : prng_data->rest;
prng_data->rest -= n;
} else {
/* generate one chunk of random bytes into read buf */
p = prng_data->buf;
n = prng_sha512_generate(p, prng_chunk_size);
if (n < 0) {
ret = n;
break;
}
if (nbytes < prng_chunk_size) {
n = nbytes;
prng_data->rest = prng_chunk_size - n;
} else {
n = prng_chunk_size;
prng_data->rest = 0;
}
}
if (copy_to_user(ubuf, p, n)) {
ret = -EFAULT;
break;
}
memzero_explicit(p, n);
ubuf += n;
nbytes -= n;
ret += n;
}
/* unlock prng_data struct */
mutex_unlock(&prng_data->mutex);
return ret;
}
/*** sysfs stuff ***/
static const struct file_operations prng_sha512_fops = {
.owner = THIS_MODULE,
.open = &prng_open,
.release = NULL,
.read = &prng_sha512_read,
.llseek = noop_llseek,
};
static const struct file_operations prng_tdes_fops = {
.owner = THIS_MODULE,
.open = &prng_open,
.release = NULL,
.read = &prng_tdes_read,
.llseek = noop_llseek,
};
static struct miscdevice prng_sha512_dev = {
.name = "prandom",
.minor = MISC_DYNAMIC_MINOR,
.mode = 0644,
.fops = &prng_sha512_fops,
};
static struct miscdevice prng_tdes_dev = {
.name = "prandom",
.minor = MISC_DYNAMIC_MINOR,
.mode = 0644,
.fops = &prng_tdes_fops,
};
/* chunksize attribute (ro) */
static ssize_t prng_chunksize_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return snprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
}
static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);
/* counter attribute (ro) */
static ssize_t prng_counter_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
u64 counter;
if (mutex_lock_interruptible(&prng_data->mutex))
return -ERESTARTSYS;
if (prng_mode == PRNG_MODE_SHA512)
counter = prng_data->prnows.stream_bytes;
else
counter = prng_data->prngws.byte_counter;
mutex_unlock(&prng_data->mutex);
return snprintf(buf, PAGE_SIZE, "%llu\n", counter);
}
static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);
/* errorflag attribute (ro) */
static ssize_t prng_errorflag_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return snprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
}
static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);
/* mode attribute (ro) */
static ssize_t prng_mode_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (prng_mode == PRNG_MODE_TDES)
return snprintf(buf, PAGE_SIZE, "TDES\n");
else
return snprintf(buf, PAGE_SIZE, "SHA512\n");
}
static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);
/* reseed attribute (w) */
static ssize_t prng_reseed_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
if (mutex_lock_interruptible(&prng_data->mutex))
return -ERESTARTSYS;
prng_sha512_reseed();
mutex_unlock(&prng_data->mutex);
return count;
}
static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store);
/* reseed limit attribute (rw) */
static ssize_t prng_reseed_limit_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return snprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
}
static ssize_t prng_reseed_limit_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
unsigned limit;
if (sscanf(buf, "%u\n", &limit) != 1)
return -EINVAL;
if (prng_mode == PRNG_MODE_SHA512) {
if (limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
return -EINVAL;
} else {
if (limit < PRNG_RESEED_LIMIT_TDES_LOWER)
return -EINVAL;
}
prng_reseed_limit = limit;
return count;
}
static DEVICE_ATTR(reseed_limit, 0644,
prng_reseed_limit_show, prng_reseed_limit_store);
/* strength attribute (ro) */
static ssize_t prng_strength_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return snprintf(buf, PAGE_SIZE, "256\n");
}
static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);
static struct attribute *prng_sha512_dev_attrs[] = {
&dev_attr_errorflag.attr,
&dev_attr_chunksize.attr,
&dev_attr_byte_counter.attr,
&dev_attr_mode.attr,
&dev_attr_reseed.attr,
&dev_attr_reseed_limit.attr,
&dev_attr_strength.attr,
NULL
};
static struct attribute *prng_tdes_dev_attrs[] = {
&dev_attr_chunksize.attr,
&dev_attr_byte_counter.attr,
&dev_attr_mode.attr,
NULL
};
static struct attribute_group prng_sha512_dev_attr_group = {
.attrs = prng_sha512_dev_attrs
};
static struct attribute_group prng_tdes_dev_attr_group = {
.attrs = prng_tdes_dev_attrs
};
/*** module init and exit ***/
static int __init prng_init(void)
{
int ret;
/* check if the CPU has a PRNG */
if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG))
return -ENODEV;
/* check if TRNG subfunction is available */
if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
trng_available = true;
/* choose prng mode */
if (prng_mode != PRNG_MODE_TDES) {
/* check for MSA5 support for PRNO operations */
if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN)) {
if (prng_mode == PRNG_MODE_SHA512) {
pr_err("The prng module cannot "
"start in SHA-512 mode\n");
return -ENODEV;
}
prng_mode = PRNG_MODE_TDES;
} else
prng_mode = PRNG_MODE_SHA512;
}
if (prng_mode == PRNG_MODE_SHA512) {
/* SHA512 mode */
if (prng_chunk_size < PRNG_CHUNKSIZE_SHA512_MIN
|| prng_chunk_size > PRNG_CHUNKSIZE_SHA512_MAX)
return -EINVAL;
prng_chunk_size = (prng_chunk_size + 0x3f) & ~0x3f;
if (prng_reseed_limit == 0)
prng_reseed_limit = PRNG_RESEED_LIMIT_SHA512;
else if (prng_reseed_limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
return -EINVAL;
ret = prng_sha512_instantiate();
if (ret)
goto out;
ret = misc_register(&prng_sha512_dev);
if (ret) {
prng_sha512_deinstantiate();
goto out;
}
ret = sysfs_create_group(&prng_sha512_dev.this_device->kobj,
&prng_sha512_dev_attr_group);
if (ret) {
misc_deregister(&prng_sha512_dev);
prng_sha512_deinstantiate();
goto out;
}
} else {
/* TDES mode */
if (prng_chunk_size < PRNG_CHUNKSIZE_TDES_MIN
|| prng_chunk_size > PRNG_CHUNKSIZE_TDES_MAX)
return -EINVAL;
prng_chunk_size = (prng_chunk_size + 0x07) & ~0x07;
if (prng_reseed_limit == 0)
prng_reseed_limit = PRNG_RESEED_LIMIT_TDES;
else if (prng_reseed_limit < PRNG_RESEED_LIMIT_TDES_LOWER)
return -EINVAL;
ret = prng_tdes_instantiate();
if (ret)
goto out;
ret = misc_register(&prng_tdes_dev);
if (ret) {
prng_tdes_deinstantiate();
goto out;
}
ret = sysfs_create_group(&prng_tdes_dev.this_device->kobj,
&prng_tdes_dev_attr_group);
if (ret) {
misc_deregister(&prng_tdes_dev);
prng_tdes_deinstantiate();
goto out;
}
}
out:
return ret;
}
static void __exit prng_exit(void)
{
if (prng_mode == PRNG_MODE_SHA512) {
sysfs_remove_group(&prng_sha512_dev.this_device->kobj,
&prng_sha512_dev_attr_group);
misc_deregister(&prng_sha512_dev);
prng_sha512_deinstantiate();
} else {
sysfs_remove_group(&prng_tdes_dev.this_device->kobj,
&prng_tdes_dev_attr_group);
misc_deregister(&prng_tdes_dev);
prng_tdes_deinstantiate();
}
}
module_cpu_feature_match(MSA, prng_init);
module_exit(prng_exit);
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