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911 lines
24 KiB
911 lines
24 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright IBM Corp. 2006, 2015 |
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* Author(s): Jan Glauber <[email protected]> |
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* Harald Freudenberger <[email protected]> |
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* Driver for the s390 pseudo random number generator |
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*/ |
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#define KMSG_COMPONENT "prng" |
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
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#include <linux/fs.h> |
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#include <linux/fips.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/device.h> |
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#include <linux/miscdevice.h> |
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#include <linux/module.h> |
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#include <linux/moduleparam.h> |
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#include <linux/mutex.h> |
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#include <linux/cpufeature.h> |
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#include <linux/random.h> |
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#include <linux/slab.h> |
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#include <linux/sched/signal.h> |
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#include <asm/debug.h> |
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#include <linux/uaccess.h> |
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#include <asm/timex.h> |
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#include <asm/cpacf.h> |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("IBM Corporation"); |
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MODULE_DESCRIPTION("s390 PRNG interface"); |
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#define PRNG_MODE_AUTO 0 |
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#define PRNG_MODE_TDES 1 |
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#define PRNG_MODE_SHA512 2 |
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static unsigned int prng_mode = PRNG_MODE_AUTO; |
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module_param_named(mode, prng_mode, int, 0); |
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MODULE_PARM_DESC(prng_mode, "PRNG mode: 0 - auto, 1 - TDES, 2 - SHA512"); |
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#define PRNG_CHUNKSIZE_TDES_MIN 8 |
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#define PRNG_CHUNKSIZE_TDES_MAX (64*1024) |
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#define PRNG_CHUNKSIZE_SHA512_MIN 64 |
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#define PRNG_CHUNKSIZE_SHA512_MAX (64*1024) |
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static unsigned int prng_chunk_size = 256; |
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module_param_named(chunksize, prng_chunk_size, int, 0); |
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MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes"); |
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#define PRNG_RESEED_LIMIT_TDES 4096 |
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#define PRNG_RESEED_LIMIT_TDES_LOWER 4096 |
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#define PRNG_RESEED_LIMIT_SHA512 100000 |
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#define PRNG_RESEED_LIMIT_SHA512_LOWER 10000 |
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static unsigned int prng_reseed_limit; |
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module_param_named(reseed_limit, prng_reseed_limit, int, 0); |
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MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit"); |
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static bool trng_available; |
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/* |
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* Any one who considers arithmetical methods of producing random digits is, |
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* of course, in a state of sin. -- John von Neumann |
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*/ |
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static int prng_errorflag; |
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#define PRNG_GEN_ENTROPY_FAILED 1 |
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#define PRNG_SELFTEST_FAILED 2 |
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#define PRNG_INSTANTIATE_FAILED 3 |
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#define PRNG_SEED_FAILED 4 |
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#define PRNG_RESEED_FAILED 5 |
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#define PRNG_GEN_FAILED 6 |
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struct prng_ws_s { |
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u8 parm_block[32]; |
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u32 reseed_counter; |
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u64 byte_counter; |
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}; |
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struct prno_ws_s { |
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u32 res; |
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u32 reseed_counter; |
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u64 stream_bytes; |
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u8 V[112]; |
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u8 C[112]; |
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}; |
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struct prng_data_s { |
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struct mutex mutex; |
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union { |
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struct prng_ws_s prngws; |
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struct prno_ws_s prnows; |
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}; |
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u8 *buf; |
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u32 rest; |
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u8 *prev; |
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}; |
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static struct prng_data_s *prng_data; |
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/* initial parameter block for tdes mode, copied from libica */ |
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static const u8 initial_parm_block[32] __initconst = { |
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0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52, |
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0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4, |
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0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF, |
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0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 }; |
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/*** helper functions ***/ |
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/* |
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* generate_entropy: |
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* This function fills a given buffer with random bytes. The entropy within |
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* the random bytes given back is assumed to have at least 50% - meaning |
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* a 64 bytes buffer has at least 64 * 8 / 2 = 256 bits of entropy. |
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* Within the function the entropy generation is done in junks of 64 bytes. |
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* So the caller should also ask for buffer fill in multiples of 64 bytes. |
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* The generation of the entropy is based on the assumption that every stckf() |
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* invocation produces 0.5 bits of entropy. To accumulate 256 bits of entropy |
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* at least 512 stckf() values are needed. The entropy relevant part of the |
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* stckf value is bit 51 (counting starts at the left with bit nr 0) so |
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* here we use the lower 4 bytes and exor the values into 2k of bufferspace. |
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* To be on the save side, if there is ever a problem with stckf() the |
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* other half of the page buffer is filled with bytes from urandom via |
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* get_random_bytes(), so this function consumes 2k of urandom for each |
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* requested 64 bytes output data. Finally the buffer page is condensed into |
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* a 64 byte value by hashing with a SHA512 hash. |
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*/ |
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static int generate_entropy(u8 *ebuf, size_t nbytes) |
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{ |
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int n, ret = 0; |
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u8 *pg, pblock[80] = { |
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/* 8 x 64 bit init values */ |
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0x6A, 0x09, 0xE6, 0x67, 0xF3, 0xBC, 0xC9, 0x08, |
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0xBB, 0x67, 0xAE, 0x85, 0x84, 0xCA, 0xA7, 0x3B, |
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0x3C, 0x6E, 0xF3, 0x72, 0xFE, 0x94, 0xF8, 0x2B, |
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0xA5, 0x4F, 0xF5, 0x3A, 0x5F, 0x1D, 0x36, 0xF1, |
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0x51, 0x0E, 0x52, 0x7F, 0xAD, 0xE6, 0x82, 0xD1, |
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0x9B, 0x05, 0x68, 0x8C, 0x2B, 0x3E, 0x6C, 0x1F, |
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0x1F, 0x83, 0xD9, 0xAB, 0xFB, 0x41, 0xBD, 0x6B, |
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0x5B, 0xE0, 0xCD, 0x19, 0x13, 0x7E, 0x21, 0x79, |
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/* 128 bit counter total message bit length */ |
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00 }; |
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/* allocate one page stckf buffer */ |
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pg = (u8 *) __get_free_page(GFP_KERNEL); |
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if (!pg) { |
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prng_errorflag = PRNG_GEN_ENTROPY_FAILED; |
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return -ENOMEM; |
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} |
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/* fill the ebuf in chunks of 64 byte each */ |
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while (nbytes) { |
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/* fill lower 2k with urandom bytes */ |
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get_random_bytes(pg, PAGE_SIZE / 2); |
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/* exor upper 2k with 512 stckf values, offset 4 bytes each */ |
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for (n = 0; n < 512; n++) { |
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int offset = (PAGE_SIZE / 2) + (n * 4) - 4; |
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u64 *p = (u64 *)(pg + offset); |
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*p ^= get_tod_clock_fast(); |
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} |
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/* hash over the filled page */ |
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cpacf_klmd(CPACF_KLMD_SHA_512, pblock, pg, PAGE_SIZE); |
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n = (nbytes < 64) ? nbytes : 64; |
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memcpy(ebuf, pblock, n); |
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ret += n; |
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ebuf += n; |
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nbytes -= n; |
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} |
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memzero_explicit(pblock, sizeof(pblock)); |
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memzero_explicit(pg, PAGE_SIZE); |
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free_page((unsigned long)pg); |
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return ret; |
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} |
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/*** tdes functions ***/ |
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static void prng_tdes_add_entropy(void) |
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{ |
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__u64 entropy[4]; |
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unsigned int i; |
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for (i = 0; i < 16; i++) { |
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cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block, |
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(char *) entropy, (char *) entropy, |
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sizeof(entropy)); |
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memcpy(prng_data->prngws.parm_block, entropy, sizeof(entropy)); |
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} |
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} |
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static void prng_tdes_seed(int nbytes) |
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{ |
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char buf[16]; |
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int i = 0; |
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BUG_ON(nbytes > sizeof(buf)); |
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get_random_bytes(buf, nbytes); |
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/* Add the entropy */ |
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while (nbytes >= 8) { |
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*((__u64 *)prng_data->prngws.parm_block) ^= *((__u64 *)(buf+i)); |
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prng_tdes_add_entropy(); |
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i += 8; |
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nbytes -= 8; |
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} |
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prng_tdes_add_entropy(); |
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prng_data->prngws.reseed_counter = 0; |
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} |
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static int __init prng_tdes_instantiate(void) |
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{ |
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int datalen; |
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pr_debug("prng runs in TDES mode with " |
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"chunksize=%d and reseed_limit=%u\n", |
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prng_chunk_size, prng_reseed_limit); |
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/* memory allocation, prng_data struct init, mutex init */ |
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datalen = sizeof(struct prng_data_s) + prng_chunk_size; |
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prng_data = kzalloc(datalen, GFP_KERNEL); |
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if (!prng_data) { |
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prng_errorflag = PRNG_INSTANTIATE_FAILED; |
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return -ENOMEM; |
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} |
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mutex_init(&prng_data->mutex); |
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prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s); |
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memcpy(prng_data->prngws.parm_block, initial_parm_block, 32); |
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/* initialize the PRNG, add 128 bits of entropy */ |
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prng_tdes_seed(16); |
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return 0; |
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} |
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static void prng_tdes_deinstantiate(void) |
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{ |
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pr_debug("The prng module stopped " |
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"after running in triple DES mode\n"); |
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kfree_sensitive(prng_data); |
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} |
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/*** sha512 functions ***/ |
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static int __init prng_sha512_selftest(void) |
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{ |
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/* NIST DRBG testvector for Hash Drbg, Sha-512, Count #0 */ |
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static const u8 seed[] __initconst = { |
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0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a, |
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0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22, |
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0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b, |
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0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c, |
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0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa, |
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0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25 }; |
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static const u8 V0[] __initconst = { |
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0x00, 0xad, 0xe3, 0x6f, 0x9a, 0x01, 0xc7, 0x76, |
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0x61, 0x34, 0x35, 0xf5, 0x4e, 0x24, 0x74, 0x22, |
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0x21, 0x9a, 0x29, 0x89, 0xc7, 0x93, 0x2e, 0x60, |
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0x1e, 0xe8, 0x14, 0x24, 0x8d, 0xd5, 0x03, 0xf1, |
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0x65, 0x5d, 0x08, 0x22, 0x72, 0xd5, 0xad, 0x95, |
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0xe1, 0x23, 0x1e, 0x8a, 0xa7, 0x13, 0xd9, 0x2b, |
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0x5e, 0xbc, 0xbb, 0x80, 0xab, 0x8d, 0xe5, 0x79, |
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0xab, 0x5b, 0x47, 0x4e, 0xdd, 0xee, 0x6b, 0x03, |
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0x8f, 0x0f, 0x5c, 0x5e, 0xa9, 0x1a, 0x83, 0xdd, |
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0xd3, 0x88, 0xb2, 0x75, 0x4b, 0xce, 0x83, 0x36, |
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0x57, 0x4b, 0xf1, 0x5c, 0xca, 0x7e, 0x09, 0xc0, |
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0xd3, 0x89, 0xc6, 0xe0, 0xda, 0xc4, 0x81, 0x7e, |
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0x5b, 0xf9, 0xe1, 0x01, 0xc1, 0x92, 0x05, 0xea, |
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0xf5, 0x2f, 0xc6, 0xc6, 0xc7, 0x8f, 0xbc, 0xf4 }; |
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static const u8 C0[] __initconst = { |
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0x00, 0xf4, 0xa3, 0xe5, 0xa0, 0x72, 0x63, 0x95, |
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0xc6, 0x4f, 0x48, 0xd0, 0x8b, 0x5b, 0x5f, 0x8e, |
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0x6b, 0x96, 0x1f, 0x16, 0xed, 0xbc, 0x66, 0x94, |
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0x45, 0x31, 0xd7, 0x47, 0x73, 0x22, 0xa5, 0x86, |
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0xce, 0xc0, 0x4c, 0xac, 0x63, 0xb8, 0x39, 0x50, |
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0xbf, 0xe6, 0x59, 0x6c, 0x38, 0x58, 0x99, 0x1f, |
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0x27, 0xa7, 0x9d, 0x71, 0x2a, 0xb3, 0x7b, 0xf9, |
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0xfb, 0x17, 0x86, 0xaa, 0x99, 0x81, 0xaa, 0x43, |
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0xe4, 0x37, 0xd3, 0x1e, 0x6e, 0xe5, 0xe6, 0xee, |
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0xc2, 0xed, 0x95, 0x4f, 0x53, 0x0e, 0x46, 0x8a, |
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0xcc, 0x45, 0xa5, 0xdb, 0x69, 0x0d, 0x81, 0xc9, |
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0x32, 0x92, 0xbc, 0x8f, 0x33, 0xe6, 0xf6, 0x09, |
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0x7c, 0x8e, 0x05, 0x19, 0x0d, 0xf1, 0xb6, 0xcc, |
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0xf3, 0x02, 0x21, 0x90, 0x25, 0xec, 0xed, 0x0e }; |
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static const u8 random[] __initconst = { |
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0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57, |
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0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6, |
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0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d, |
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0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf, |
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0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26, |
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0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64, |
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0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55, |
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0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a, |
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0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78, |
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0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e, |
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0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb, |
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0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30, |
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0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19, |
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0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f, |
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0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d, |
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0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a, |
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0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2, |
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0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd, |
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0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd, |
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0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2, |
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0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b, |
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0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1, |
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0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99, |
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0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e, |
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0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3, |
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0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67, |
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0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3, |
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0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d, |
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0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b, |
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0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13, |
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0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c, |
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0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2 }; |
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u8 buf[sizeof(random)]; |
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struct prno_ws_s ws; |
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memset(&ws, 0, sizeof(ws)); |
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/* initial seed */ |
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cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, |
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&ws, NULL, 0, seed, sizeof(seed)); |
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/* check working states V and C */ |
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if (memcmp(ws.V, V0, sizeof(V0)) != 0 |
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|| memcmp(ws.C, C0, sizeof(C0)) != 0) { |
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pr_err("The prng self test state test " |
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"for the SHA-512 mode failed\n"); |
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prng_errorflag = PRNG_SELFTEST_FAILED; |
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return -EIO; |
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} |
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/* generate random bytes */ |
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cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, |
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&ws, buf, sizeof(buf), NULL, 0); |
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cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, |
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&ws, buf, sizeof(buf), NULL, 0); |
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/* check against expected data */ |
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if (memcmp(buf, random, sizeof(random)) != 0) { |
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pr_err("The prng self test data test " |
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"for the SHA-512 mode failed\n"); |
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prng_errorflag = PRNG_SELFTEST_FAILED; |
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return -EIO; |
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} |
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return 0; |
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} |
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static int __init prng_sha512_instantiate(void) |
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{ |
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int ret, datalen, seedlen; |
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u8 seed[128 + 16]; |
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pr_debug("prng runs in SHA-512 mode " |
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"with chunksize=%d and reseed_limit=%u\n", |
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prng_chunk_size, prng_reseed_limit); |
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/* memory allocation, prng_data struct init, mutex init */ |
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datalen = sizeof(struct prng_data_s) + prng_chunk_size; |
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if (fips_enabled) |
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datalen += prng_chunk_size; |
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prng_data = kzalloc(datalen, GFP_KERNEL); |
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if (!prng_data) { |
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prng_errorflag = PRNG_INSTANTIATE_FAILED; |
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return -ENOMEM; |
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} |
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mutex_init(&prng_data->mutex); |
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prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s); |
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/* selftest */ |
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ret = prng_sha512_selftest(); |
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if (ret) |
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goto outfree; |
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/* generate initial seed, we need at least 256 + 128 bits entropy. */ |
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if (trng_available) { |
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/* |
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* Trng available, so use it. The trng works in chunks of |
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* 32 bytes and produces 100% entropy. So we pull 64 bytes |
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* which gives us 512 bits entropy. |
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*/ |
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seedlen = 2 * 32; |
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cpacf_trng(NULL, 0, seed, seedlen); |
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} else { |
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/* |
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* No trng available, so use the generate_entropy() function. |
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* This function works in 64 byte junks and produces |
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* 50% entropy. So we pull 2*64 bytes which gives us 512 bits |
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* of entropy. |
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*/ |
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seedlen = 2 * 64; |
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ret = generate_entropy(seed, seedlen); |
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if (ret != seedlen) |
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goto outfree; |
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} |
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/* append the seed by 16 bytes of unique nonce */ |
|
store_tod_clock_ext((union tod_clock *)(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"); |
|
kfree_sensitive(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, |
|
}; |
|
|
|
/* chunksize attribute (ro) */ |
|
static ssize_t prng_chunksize_show(struct device *dev, |
|
struct device_attribute *attr, |
|
char *buf) |
|
{ |
|
return scnprintf(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 scnprintf(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 scnprintf(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 scnprintf(buf, PAGE_SIZE, "TDES\n"); |
|
else |
|
return scnprintf(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 scnprintf(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 scnprintf(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 |
|
}; |
|
ATTRIBUTE_GROUPS(prng_sha512_dev); |
|
|
|
static struct attribute *prng_tdes_dev_attrs[] = { |
|
&dev_attr_chunksize.attr, |
|
&dev_attr_byte_counter.attr, |
|
&dev_attr_mode.attr, |
|
NULL |
|
}; |
|
ATTRIBUTE_GROUPS(prng_tdes_dev); |
|
|
|
static struct miscdevice prng_sha512_dev = { |
|
.name = "prandom", |
|
.minor = MISC_DYNAMIC_MINOR, |
|
.mode = 0644, |
|
.fops = &prng_sha512_fops, |
|
.groups = prng_sha512_dev_groups, |
|
}; |
|
|
|
static struct miscdevice prng_tdes_dev = { |
|
.name = "prandom", |
|
.minor = MISC_DYNAMIC_MINOR, |
|
.mode = 0644, |
|
.fops = &prng_tdes_fops, |
|
.groups = prng_tdes_dev_groups, |
|
}; |
|
|
|
|
|
/*** 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; |
|
} |
|
|
|
} 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; |
|
} |
|
} |
|
|
|
out: |
|
return ret; |
|
} |
|
|
|
|
|
static void __exit prng_exit(void) |
|
{ |
|
if (prng_mode == PRNG_MODE_SHA512) { |
|
misc_deregister(&prng_sha512_dev); |
|
prng_sha512_deinstantiate(); |
|
} else { |
|
misc_deregister(&prng_tdes_dev); |
|
prng_tdes_deinstantiate(); |
|
} |
|
} |
|
|
|
module_cpu_feature_match(MSA, prng_init); |
|
module_exit(prng_exit);
|
|
|