diff options
Diffstat (limited to 'crypto/jitterentropy-kcapi.c')
| -rw-r--r-- | crypto/jitterentropy-kcapi.c | 247 |
1 files changed, 205 insertions, 42 deletions
diff --git a/crypto/jitterentropy-kcapi.c b/crypto/jitterentropy-kcapi.c index 787dccca3715..7c880cf34c52 100644 --- a/crypto/jitterentropy-kcapi.c +++ b/crypto/jitterentropy-kcapi.c @@ -2,7 +2,7 @@ * Non-physical true random number generator based on timing jitter -- * Linux Kernel Crypto API specific code * - * Copyright Stephan Mueller <smueller@chronox.de>, 2015 + * Copyright Stephan Mueller <smueller@chronox.de>, 2015 - 2023 * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -37,53 +37,41 @@ * DAMAGE. */ +#include <crypto/hash.h> +#include <crypto/sha3.h> +#include <linux/fips.h> +#include <linux/kernel.h> #include <linux/module.h> #include <linux/slab.h> -#include <linux/fips.h> #include <linux/time.h> -#include <linux/crypto.h> #include <crypto/internal/rng.h> -struct rand_data; -int jent_read_entropy(struct rand_data *ec, unsigned char *data, - unsigned int len); -int jent_entropy_init(void); -struct rand_data *jent_entropy_collector_alloc(unsigned int osr, - unsigned int flags); -void jent_entropy_collector_free(struct rand_data *entropy_collector); +#include "jitterentropy.h" + +#define JENT_CONDITIONING_HASH "sha3-256" /*************************************************************************** * Helper function ***************************************************************************/ -__u64 jent_rol64(__u64 word, unsigned int shift) -{ - return rol64(word, shift); -} - -void *jent_zalloc(unsigned int len) -{ - return kzalloc(len, GFP_KERNEL); -} - -void jent_zfree(void *ptr) +void *jent_kvzalloc(unsigned int len) { - kzfree(ptr); + return kvzalloc(len, GFP_KERNEL); } -int jent_fips_enabled(void) +void jent_kvzfree(void *ptr, unsigned int len) { - return fips_enabled; + kvfree_sensitive(ptr, len); } -void jent_panic(char *s) +void *jent_zalloc(unsigned int len) { - panic("%s", s); + return kzalloc(len, GFP_KERNEL); } -void jent_memcpy(void *dest, const void *src, unsigned int n) +void jent_zfree(void *ptr) { - memcpy(dest, src, n); + kfree_sensitive(ptr); } /* @@ -110,6 +98,94 @@ void jent_get_nstime(__u64 *out) tmp = ktime_get_ns(); *out = tmp; + jent_raw_hires_entropy_store(tmp); +} + +int jent_hash_time(void *hash_state, __u64 time, u8 *addtl, + unsigned int addtl_len, __u64 hash_loop_cnt, + unsigned int stuck) +{ + struct shash_desc *hash_state_desc = (struct shash_desc *)hash_state; + SHASH_DESC_ON_STACK(desc, hash_state_desc->tfm); + u8 intermediary[SHA3_256_DIGEST_SIZE]; + __u64 j = 0; + int ret; + + desc->tfm = hash_state_desc->tfm; + + if (sizeof(intermediary) != crypto_shash_digestsize(desc->tfm)) { + pr_warn_ratelimited("Unexpected digest size\n"); + return -EINVAL; + } + kmsan_unpoison_memory(intermediary, sizeof(intermediary)); + + /* + * This loop fills a buffer which is injected into the entropy pool. + * The main reason for this loop is to execute something over which we + * can perform a timing measurement. The injection of the resulting + * data into the pool is performed to ensure the result is used and + * the compiler cannot optimize the loop away in case the result is not + * used at all. Yet that data is considered "additional information" + * considering the terminology from SP800-90A without any entropy. + * + * Note, it does not matter which or how much data you inject, we are + * interested in one Keccack1600 compression operation performed with + * the crypto_shash_final. + */ + for (j = 0; j < hash_loop_cnt; j++) { + ret = crypto_shash_init(desc) ?: + crypto_shash_update(desc, intermediary, + sizeof(intermediary)) ?: + crypto_shash_finup(desc, addtl, addtl_len, intermediary); + if (ret) + goto err; + } + + /* + * Inject the data from the previous loop into the pool. This data is + * not considered to contain any entropy, but it stirs the pool a bit. + */ + ret = crypto_shash_update(hash_state_desc, intermediary, sizeof(intermediary)); + if (ret) + goto err; + + /* + * Insert the time stamp into the hash context representing the pool. + * + * If the time stamp is stuck, do not finally insert the value into the + * entropy pool. Although this operation should not do any harm even + * when the time stamp has no entropy, SP800-90B requires that any + * conditioning operation to have an identical amount of input data + * according to section 3.1.5. + */ + if (stuck) { + time = 0; + } + + ret = crypto_shash_update(hash_state_desc, (u8 *)&time, sizeof(__u64)); + +err: + shash_desc_zero(desc); + memzero_explicit(intermediary, sizeof(intermediary)); + + return ret; +} + +int jent_read_random_block(void *hash_state, char *dst, unsigned int dst_len) +{ + struct shash_desc *hash_state_desc = (struct shash_desc *)hash_state; + u8 jent_block[SHA3_256_DIGEST_SIZE]; + /* Obtain data from entropy pool and re-initialize it */ + int ret = crypto_shash_final(hash_state_desc, jent_block) ?: + crypto_shash_init(hash_state_desc) ?: + crypto_shash_update(hash_state_desc, jent_block, + sizeof(jent_block)); + + if (!ret && dst_len) + memcpy(dst, jent_block, dst_len); + + memzero_explicit(jent_block, sizeof(jent_block)); + return ret; } /*************************************************************************** @@ -119,32 +195,76 @@ void jent_get_nstime(__u64 *out) struct jitterentropy { spinlock_t jent_lock; struct rand_data *entropy_collector; + struct crypto_shash *tfm; + struct shash_desc *sdesc; }; -static int jent_kcapi_init(struct crypto_tfm *tfm) +static void jent_kcapi_cleanup(struct crypto_tfm *tfm) { struct jitterentropy *rng = crypto_tfm_ctx(tfm); - int ret = 0; - rng->entropy_collector = jent_entropy_collector_alloc(1, 0); - if (!rng->entropy_collector) - ret = -ENOMEM; + spin_lock(&rng->jent_lock); - spin_lock_init(&rng->jent_lock); - return ret; -} + if (rng->sdesc) { + shash_desc_zero(rng->sdesc); + kfree(rng->sdesc); + } + rng->sdesc = NULL; -static void jent_kcapi_cleanup(struct crypto_tfm *tfm) -{ - struct jitterentropy *rng = crypto_tfm_ctx(tfm); + if (rng->tfm) + crypto_free_shash(rng->tfm); + rng->tfm = NULL; - spin_lock(&rng->jent_lock); if (rng->entropy_collector) jent_entropy_collector_free(rng->entropy_collector); rng->entropy_collector = NULL; spin_unlock(&rng->jent_lock); } +static int jent_kcapi_init(struct crypto_tfm *tfm) +{ + struct jitterentropy *rng = crypto_tfm_ctx(tfm); + struct crypto_shash *hash; + struct shash_desc *sdesc; + int size, ret = 0; + + spin_lock_init(&rng->jent_lock); + + /* Use SHA3-256 as conditioner */ + hash = crypto_alloc_shash(JENT_CONDITIONING_HASH, 0, 0); + if (IS_ERR(hash)) { + pr_err("Cannot allocate conditioning digest\n"); + return PTR_ERR(hash); + } + rng->tfm = hash; + + size = sizeof(struct shash_desc) + crypto_shash_descsize(hash); + sdesc = kmalloc(size, GFP_KERNEL); + if (!sdesc) { + ret = -ENOMEM; + goto err; + } + + sdesc->tfm = hash; + crypto_shash_init(sdesc); + rng->sdesc = sdesc; + + rng->entropy_collector = + jent_entropy_collector_alloc(CONFIG_CRYPTO_JITTERENTROPY_OSR, 0, + sdesc); + if (!rng->entropy_collector) { + ret = -ENOMEM; + goto err; + } + + spin_lock_init(&rng->jent_lock); + return 0; + +err: + jent_kcapi_cleanup(tfm); + return ret; +} + static int jent_kcapi_random(struct crypto_rng *tfm, const u8 *src, unsigned int slen, u8 *rdata, unsigned int dlen) @@ -153,7 +273,31 @@ static int jent_kcapi_random(struct crypto_rng *tfm, int ret = 0; spin_lock(&rng->jent_lock); + ret = jent_read_entropy(rng->entropy_collector, rdata, dlen); + + if (ret == -3) { + /* Handle permanent health test error */ + /* + * If the kernel was booted with fips=1, it implies that + * the entire kernel acts as a FIPS 140 module. In this case + * an SP800-90B permanent health test error is treated as + * a FIPS module error. + */ + if (fips_enabled) + panic("Jitter RNG permanent health test failure\n"); + + pr_err("Jitter RNG permanent health test failure\n"); + ret = -EFAULT; + } else if (ret == -2) { + /* Handle intermittent health test error */ + pr_warn_ratelimited("Reset Jitter RNG due to intermittent health test failure\n"); + ret = -EAGAIN; + } else if (ret == -1) { + /* Handle other errors */ + ret = -EINVAL; + } + spin_unlock(&rng->jent_lock); return ret; @@ -177,16 +321,34 @@ static struct rng_alg jent_alg = { .cra_module = THIS_MODULE, .cra_init = jent_kcapi_init, .cra_exit = jent_kcapi_cleanup, - } }; static int __init jent_mod_init(void) { + SHASH_DESC_ON_STACK(desc, tfm); + struct crypto_shash *tfm; int ret = 0; - ret = jent_entropy_init(); + jent_testing_init(); + + tfm = crypto_alloc_shash(JENT_CONDITIONING_HASH, 0, 0); + if (IS_ERR(tfm)) { + jent_testing_exit(); + return PTR_ERR(tfm); + } + + desc->tfm = tfm; + crypto_shash_init(desc); + ret = jent_entropy_init(CONFIG_CRYPTO_JITTERENTROPY_OSR, 0, desc, NULL); + shash_desc_zero(desc); + crypto_free_shash(tfm); if (ret) { + /* Handle permanent health test error */ + if (fips_enabled) + panic("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret); + + jent_testing_exit(); pr_info("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret); return -EFAULT; } @@ -195,6 +357,7 @@ static int __init jent_mod_init(void) static void __exit jent_mod_exit(void) { + jent_testing_exit(); crypto_unregister_rng(&jent_alg); } |