mirror of
https://github.com/torvalds/linux.git
synced 2024-12-26 12:52:30 +00:00
crypto: jitter - SP800-90B compliance
SP800-90B specifies various requirements for the noise source(s) that may seed any DRNG including SP800-90A DRBGs. In November 2020, SP800-90B will be mandated for all noise sources that provide entropy to DRBGs as part of a FIPS 140-[2|3] validation or other evaluation types. Without SP800-90B compliance, a noise source is defined to always deliver zero bits of entropy. This patch ports the SP800-90B compliance from the user space Jitter RNG version 2.2.0. The following changes are applied: - addition of (an enhanced version of) the repetitive count test (RCT) from SP800-90B section 4.4.1 - the enhancement is due to the fact of using the stuck test as input to the RCT. - addition of the adaptive proportion test (APT) from SP800-90B section 4.4.2 - update of the power-on self test to perform a test measurement of 1024 noise samples compliant to SP800-90B section 4.3 - remove of the continuous random number generator test which is replaced by APT and RCT Health test failures due to the SP800-90B operation are only enforced in FIPS mode. If a runtime health test failure is detected, the Jitter RNG is reset. If more than 1024 resets in a row are performed, a permanent error is returned to the caller. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Müller
Herbert Xu
parent
63e05f3275
commit
764428fe99
@ -108,6 +108,7 @@ void jent_get_nstime(__u64 *out)
|
||||
struct jitterentropy {
|
||||
spinlock_t jent_lock;
|
||||
struct rand_data *entropy_collector;
|
||||
unsigned int reset_cnt;
|
||||
};
|
||||
|
||||
static int jent_kcapi_init(struct crypto_tfm *tfm)
|
||||
@ -142,7 +143,33 @@ static int jent_kcapi_random(struct crypto_rng *tfm,
|
||||
int ret = 0;
|
||||
|
||||
spin_lock(&rng->jent_lock);
|
||||
|
||||
/* Return a permanent error in case we had too many resets in a row. */
|
||||
if (rng->reset_cnt > (1<<10)) {
|
||||
ret = -EFAULT;
|
||||
goto out;
|
||||
}
|
||||
|
||||
ret = jent_read_entropy(rng->entropy_collector, rdata, dlen);
|
||||
|
||||
/* Reset RNG in case of health failures */
|
||||
if (ret < -1) {
|
||||
pr_warn_ratelimited("Reset Jitter RNG due to health test failure: %s failure\n",
|
||||
(ret == -2) ? "Repetition Count Test" :
|
||||
"Adaptive Proportion Test");
|
||||
|
||||
rng->reset_cnt++;
|
||||
|
||||
ret = -EAGAIN;
|
||||
} else {
|
||||
rng->reset_cnt = 0;
|
||||
|
||||
/* Convert the Jitter RNG error into a usable error code */
|
||||
if (ret == -1)
|
||||
ret = -EINVAL;
|
||||
}
|
||||
|
||||
out:
|
||||
spin_unlock(&rng->jent_lock);
|
||||
|
||||
return ret;
|
||||
|
||||
@ -2,7 +2,7 @@
|
||||
* Non-physical true random number generator based on timing jitter --
|
||||
* Jitter RNG standalone code.
|
||||
*
|
||||
* Copyright Stephan Mueller <smueller@chronox.de>, 2015 - 2019
|
||||
* Copyright Stephan Mueller <smueller@chronox.de>, 2015 - 2020
|
||||
*
|
||||
* Design
|
||||
* ======
|
||||
@ -47,7 +47,7 @@
|
||||
|
||||
/*
|
||||
* This Jitterentropy RNG is based on the jitterentropy library
|
||||
* version 2.1.2 provided at http://www.chronox.de/jent.html
|
||||
* version 2.2.0 provided at http://www.chronox.de/jent.html
|
||||
*/
|
||||
|
||||
#ifdef __OPTIMIZE__
|
||||
@ -83,6 +83,22 @@ struct rand_data {
|
||||
unsigned int memblocksize; /* Size of one memory block in bytes */
|
||||
unsigned int memaccessloops; /* Number of memory accesses per random
|
||||
* bit generation */
|
||||
|
||||
/* Repetition Count Test */
|
||||
int rct_count; /* Number of stuck values */
|
||||
|
||||
/* Adaptive Proportion Test for a significance level of 2^-30 */
|
||||
#define JENT_APT_CUTOFF 325 /* Taken from SP800-90B sec 4.4.2 */
|
||||
#define JENT_APT_WINDOW_SIZE 512 /* Data window size */
|
||||
/* LSB of time stamp to process */
|
||||
#define JENT_APT_LSB 16
|
||||
#define JENT_APT_WORD_MASK (JENT_APT_LSB - 1)
|
||||
unsigned int apt_observations; /* Number of collected observations */
|
||||
unsigned int apt_count; /* APT counter */
|
||||
unsigned int apt_base; /* APT base reference */
|
||||
unsigned int apt_base_set:1; /* APT base reference set? */
|
||||
|
||||
unsigned int health_failure:1; /* Permanent health failure */
|
||||
};
|
||||
|
||||
/* Flags that can be used to initialize the RNG */
|
||||
@ -98,13 +114,202 @@ struct rand_data {
|
||||
* variations (2nd derivation of time is
|
||||
* zero). */
|
||||
#define JENT_ESTUCK 8 /* Too many stuck results during init. */
|
||||
|
||||
/***************************************************************************
|
||||
* Helper functions
|
||||
***************************************************************************/
|
||||
#define JENT_EHEALTH 9 /* Health test failed during initialization */
|
||||
#define JENT_ERCT 10 /* RCT failed during initialization */
|
||||
|
||||
#include "jitterentropy.h"
|
||||
|
||||
/***************************************************************************
|
||||
* Adaptive Proportion Test
|
||||
*
|
||||
* This test complies with SP800-90B section 4.4.2.
|
||||
***************************************************************************/
|
||||
|
||||
/**
|
||||
* Reset the APT counter
|
||||
*
|
||||
* @ec [in] Reference to entropy collector
|
||||
*/
|
||||
static void jent_apt_reset(struct rand_data *ec, unsigned int delta_masked)
|
||||
{
|
||||
/* Reset APT counter */
|
||||
ec->apt_count = 0;
|
||||
ec->apt_base = delta_masked;
|
||||
ec->apt_observations = 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Insert a new entropy event into APT
|
||||
*
|
||||
* @ec [in] Reference to entropy collector
|
||||
* @delta_masked [in] Masked time delta to process
|
||||
*/
|
||||
static void jent_apt_insert(struct rand_data *ec, unsigned int delta_masked)
|
||||
{
|
||||
/* Initialize the base reference */
|
||||
if (!ec->apt_base_set) {
|
||||
ec->apt_base = delta_masked;
|
||||
ec->apt_base_set = 1;
|
||||
return;
|
||||
}
|
||||
|
||||
if (delta_masked == ec->apt_base) {
|
||||
ec->apt_count++;
|
||||
|
||||
if (ec->apt_count >= JENT_APT_CUTOFF)
|
||||
ec->health_failure = 1;
|
||||
}
|
||||
|
||||
ec->apt_observations++;
|
||||
|
||||
if (ec->apt_observations >= JENT_APT_WINDOW_SIZE)
|
||||
jent_apt_reset(ec, delta_masked);
|
||||
}
|
||||
|
||||
/***************************************************************************
|
||||
* Stuck Test and its use as Repetition Count Test
|
||||
*
|
||||
* The Jitter RNG uses an enhanced version of the Repetition Count Test
|
||||
* (RCT) specified in SP800-90B section 4.4.1. Instead of counting identical
|
||||
* back-to-back values, the input to the RCT is the counting of the stuck
|
||||
* values during the generation of one Jitter RNG output block.
|
||||
*
|
||||
* The RCT is applied with an alpha of 2^{-30} compliant to FIPS 140-2 IG 9.8.
|
||||
*
|
||||
* During the counting operation, the Jitter RNG always calculates the RCT
|
||||
* cut-off value of C. If that value exceeds the allowed cut-off value,
|
||||
* the Jitter RNG output block will be calculated completely but discarded at
|
||||
* the end. The caller of the Jitter RNG is informed with an error code.
|
||||
***************************************************************************/
|
||||
|
||||
/**
|
||||
* Repetition Count Test as defined in SP800-90B section 4.4.1
|
||||
*
|
||||
* @ec [in] Reference to entropy collector
|
||||
* @stuck [in] Indicator whether the value is stuck
|
||||
*/
|
||||
static void jent_rct_insert(struct rand_data *ec, int stuck)
|
||||
{
|
||||
/*
|
||||
* If we have a count less than zero, a previous RCT round identified
|
||||
* a failure. We will not overwrite it.
|
||||
*/
|
||||
if (ec->rct_count < 0)
|
||||
return;
|
||||
|
||||
if (stuck) {
|
||||
ec->rct_count++;
|
||||
|
||||
/*
|
||||
* The cutoff value is based on the following consideration:
|
||||
* alpha = 2^-30 as recommended in FIPS 140-2 IG 9.8.
|
||||
* In addition, we require an entropy value H of 1/OSR as this
|
||||
* is the minimum entropy required to provide full entropy.
|
||||
* Note, we collect 64 * OSR deltas for inserting them into
|
||||
* the entropy pool which should then have (close to) 64 bits
|
||||
* of entropy.
|
||||
*
|
||||
* Note, ec->rct_count (which equals to value B in the pseudo
|
||||
* code of SP800-90B section 4.4.1) starts with zero. Hence
|
||||
* we need to subtract one from the cutoff value as calculated
|
||||
* following SP800-90B.
|
||||
*/
|
||||
if ((unsigned int)ec->rct_count >= (31 * ec->osr)) {
|
||||
ec->rct_count = -1;
|
||||
ec->health_failure = 1;
|
||||
}
|
||||
} else {
|
||||
ec->rct_count = 0;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Is there an RCT health test failure?
|
||||
*
|
||||
* @ec [in] Reference to entropy collector
|
||||
*
|
||||
* @return
|
||||
* 0 No health test failure
|
||||
* 1 Permanent health test failure
|
||||
*/
|
||||
static int jent_rct_failure(struct rand_data *ec)
|
||||
{
|
||||
if (ec->rct_count < 0)
|
||||
return 1;
|
||||
return 0;
|
||||
}
|
||||
|
||||
static inline __u64 jent_delta(__u64 prev, __u64 next)
|
||||
{
|
||||
#define JENT_UINT64_MAX (__u64)(~((__u64) 0))
|
||||
return (prev < next) ? (next - prev) :
|
||||
(JENT_UINT64_MAX - prev + 1 + next);
|
||||
}
|
||||
|
||||
/**
|
||||
* Stuck test by checking the:
|
||||
* 1st derivative of the jitter measurement (time delta)
|
||||
* 2nd derivative of the jitter measurement (delta of time deltas)
|
||||
* 3rd derivative of the jitter measurement (delta of delta of time deltas)
|
||||
*
|
||||
* All values must always be non-zero.
|
||||
*
|
||||
* @ec [in] Reference to entropy collector
|
||||
* @current_delta [in] Jitter time delta
|
||||
*
|
||||
* @return
|
||||
* 0 jitter measurement not stuck (good bit)
|
||||
* 1 jitter measurement stuck (reject bit)
|
||||
*/
|
||||
static int jent_stuck(struct rand_data *ec, __u64 current_delta)
|
||||
{
|
||||
__u64 delta2 = jent_delta(ec->last_delta, current_delta);
|
||||
__u64 delta3 = jent_delta(ec->last_delta2, delta2);
|
||||
unsigned int delta_masked = current_delta & JENT_APT_WORD_MASK;
|
||||
|
||||
ec->last_delta = current_delta;
|
||||
ec->last_delta2 = delta2;
|
||||
|
||||
/*
|
||||
* Insert the result of the comparison of two back-to-back time
|
||||
* deltas.
|
||||
*/
|
||||
jent_apt_insert(ec, delta_masked);
|
||||
|
||||
if (!current_delta || !delta2 || !delta3) {
|
||||
/* RCT with a stuck bit */
|
||||
jent_rct_insert(ec, 1);
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* RCT with a non-stuck bit */
|
||||
jent_rct_insert(ec, 0);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Report any health test failures
|
||||
*
|
||||
* @ec [in] Reference to entropy collector
|
||||
*
|
||||
* @return
|
||||
* 0 No health test failure
|
||||
* 1 Permanent health test failure
|
||||
*/
|
||||
static int jent_health_failure(struct rand_data *ec)
|
||||
{
|
||||
/* Test is only enabled in FIPS mode */
|
||||
if (!jent_fips_enabled())
|
||||
return 0;
|
||||
|
||||
return ec->health_failure;
|
||||
}
|
||||
|
||||
/***************************************************************************
|
||||
* Noise sources
|
||||
***************************************************************************/
|
||||
|
||||
/**
|
||||
* Update of the loop count used for the next round of
|
||||
* an entropy collection.
|
||||
@ -148,10 +353,6 @@ static __u64 jent_loop_shuffle(struct rand_data *ec,
|
||||
return (shuffle + (1<<min));
|
||||
}
|
||||
|
||||
/***************************************************************************
|
||||
* Noise sources
|
||||
***************************************************************************/
|
||||
|
||||
/**
|
||||
* CPU Jitter noise source -- this is the noise source based on the CPU
|
||||
* execution time jitter
|
||||
@ -166,18 +367,19 @@ static __u64 jent_loop_shuffle(struct rand_data *ec,
|
||||
* the CPU execution time jitter. Any change to the loop in this function
|
||||
* implies that careful retesting must be done.
|
||||
*
|
||||
* Input:
|
||||
* @ec entropy collector struct
|
||||
* @time time stamp to be injected
|
||||
* @loop_cnt if a value not equal to 0 is set, use the given value as number of
|
||||
* loops to perform the folding
|
||||
* @ec [in] entropy collector struct
|
||||
* @time [in] time stamp to be injected
|
||||
* @loop_cnt [in] if a value not equal to 0 is set, use the given value as
|
||||
* number of loops to perform the folding
|
||||
* @stuck [in] Is the time stamp identified as stuck?
|
||||
*
|
||||
* Output:
|
||||
* updated ec->data
|
||||
*
|
||||
* @return Number of loops the folding operation is performed
|
||||
*/
|
||||
static __u64 jent_lfsr_time(struct rand_data *ec, __u64 time, __u64 loop_cnt)
|
||||
static void jent_lfsr_time(struct rand_data *ec, __u64 time, __u64 loop_cnt,
|
||||
int stuck)
|
||||
{
|
||||
unsigned int i;
|
||||
__u64 j = 0;
|
||||
@ -220,9 +422,17 @@ static __u64 jent_lfsr_time(struct rand_data *ec, __u64 time, __u64 loop_cnt)
|
||||
new ^= tmp;
|
||||
}
|
||||
}
|
||||
ec->data = new;
|
||||
|
||||
return fold_loop_cnt;
|
||||
/*
|
||||
* 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 (SP800-90B considers the LFSR to be a
|
||||
* conditioning operation) to have an identical amount of input
|
||||
* data according to section 3.1.5.
|
||||
*/
|
||||
if (!stuck)
|
||||
ec->data = new;
|
||||
}
|
||||
|
||||
/**
|
||||
@ -243,16 +453,13 @@ static __u64 jent_lfsr_time(struct rand_data *ec, __u64 time, __u64 loop_cnt)
|
||||
* to reliably access either L3 or memory, the ec->mem memory must be quite
|
||||
* large which is usually not desirable.
|
||||
*
|
||||
* Input:
|
||||
* @ec Reference to the entropy collector with the memory access data -- if
|
||||
* the reference to the memory block to be accessed is NULL, this noise
|
||||
* source is disabled
|
||||
* @loop_cnt if a value not equal to 0 is set, use the given value as number of
|
||||
* loops to perform the folding
|
||||
*
|
||||
* @return Number of memory access operations
|
||||
* @ec [in] Reference to the entropy collector with the memory access data -- if
|
||||
* the reference to the memory block to be accessed is NULL, this noise
|
||||
* source is disabled
|
||||
* @loop_cnt [in] if a value not equal to 0 is set, use the given value
|
||||
* number of loops to perform the LFSR
|
||||
*/
|
||||
static unsigned int jent_memaccess(struct rand_data *ec, __u64 loop_cnt)
|
||||
static void jent_memaccess(struct rand_data *ec, __u64 loop_cnt)
|
||||
{
|
||||
unsigned int wrap = 0;
|
||||
__u64 i = 0;
|
||||
@ -262,7 +469,7 @@ static unsigned int jent_memaccess(struct rand_data *ec, __u64 loop_cnt)
|
||||
jent_loop_shuffle(ec, MAX_ACC_LOOP_BIT, MIN_ACC_LOOP_BIT);
|
||||
|
||||
if (NULL == ec || NULL == ec->mem)
|
||||
return 0;
|
||||
return;
|
||||
wrap = ec->memblocksize * ec->memblocks;
|
||||
|
||||
/*
|
||||
@ -288,43 +495,11 @@ static unsigned int jent_memaccess(struct rand_data *ec, __u64 loop_cnt)
|
||||
ec->memlocation = ec->memlocation + ec->memblocksize - 1;
|
||||
ec->memlocation = ec->memlocation % wrap;
|
||||
}
|
||||
return i;
|
||||
}
|
||||
|
||||
/***************************************************************************
|
||||
* Start of entropy processing logic
|
||||
***************************************************************************/
|
||||
|
||||
/**
|
||||
* Stuck test by checking the:
|
||||
* 1st derivation of the jitter measurement (time delta)
|
||||
* 2nd derivation of the jitter measurement (delta of time deltas)
|
||||
* 3rd derivation of the jitter measurement (delta of delta of time deltas)
|
||||
*
|
||||
* All values must always be non-zero.
|
||||
*
|
||||
* Input:
|
||||
* @ec Reference to entropy collector
|
||||
* @current_delta Jitter time delta
|
||||
*
|
||||
* @return
|
||||
* 0 jitter measurement not stuck (good bit)
|
||||
* 1 jitter measurement stuck (reject bit)
|
||||
*/
|
||||
static int jent_stuck(struct rand_data *ec, __u64 current_delta)
|
||||
{
|
||||
__s64 delta2 = ec->last_delta - current_delta;
|
||||
__s64 delta3 = delta2 - ec->last_delta2;
|
||||
|
||||
ec->last_delta = current_delta;
|
||||
ec->last_delta2 = delta2;
|
||||
|
||||
if (!current_delta || !delta2 || !delta3)
|
||||
return 1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* This is the heart of the entropy generation: calculate time deltas and
|
||||
* use the CPU jitter in the time deltas. The jitter is injected into the
|
||||
@ -334,8 +509,7 @@ static int jent_stuck(struct rand_data *ec, __u64 current_delta)
|
||||
* of this function! This can be done by calling this function
|
||||
* and not using its result.
|
||||
*
|
||||
* Input:
|
||||
* @entropy_collector Reference to entropy collector
|
||||
* @ec [in] Reference to entropy collector
|
||||
*
|
||||
* @return result of stuck test
|
||||
*/
|
||||
@ -343,6 +517,7 @@ static int jent_measure_jitter(struct rand_data *ec)
|
||||
{
|
||||
__u64 time = 0;
|
||||
__u64 current_delta = 0;
|
||||
int stuck;
|
||||
|
||||
/* Invoke one noise source before time measurement to add variations */
|
||||
jent_memaccess(ec, 0);
|
||||
@ -352,22 +527,23 @@ static int jent_measure_jitter(struct rand_data *ec)
|
||||
* invocation to measure the timing variations
|
||||
*/
|
||||
jent_get_nstime(&time);
|
||||
current_delta = time - ec->prev_time;
|
||||
current_delta = jent_delta(ec->prev_time, time);
|
||||
ec->prev_time = time;
|
||||
|
||||
/* Now call the next noise sources which also injects the data */
|
||||
jent_lfsr_time(ec, current_delta, 0);
|
||||
|
||||
/* Check whether we have a stuck measurement. */
|
||||
return jent_stuck(ec, current_delta);
|
||||
stuck = jent_stuck(ec, current_delta);
|
||||
|
||||
/* Now call the next noise sources which also injects the data */
|
||||
jent_lfsr_time(ec, current_delta, 0, stuck);
|
||||
|
||||
return stuck;
|
||||
}
|
||||
|
||||
/**
|
||||
* Generator of one 64 bit random number
|
||||
* Function fills rand_data->data
|
||||
*
|
||||
* Input:
|
||||
* @ec Reference to entropy collector
|
||||
* @ec [in] Reference to entropy collector
|
||||
*/
|
||||
static void jent_gen_entropy(struct rand_data *ec)
|
||||
{
|
||||
@ -390,31 +566,6 @@ static void jent_gen_entropy(struct rand_data *ec)
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* The continuous test required by FIPS 140-2 -- the function automatically
|
||||
* primes the test if needed.
|
||||
*
|
||||
* Return:
|
||||
* returns normally if FIPS test passed
|
||||
* panics the kernel if FIPS test failed
|
||||
*/
|
||||
static void jent_fips_test(struct rand_data *ec)
|
||||
{
|
||||
if (!jent_fips_enabled())
|
||||
return;
|
||||
|
||||
/* prime the FIPS test */
|
||||
if (!ec->old_data) {
|
||||
ec->old_data = ec->data;
|
||||
jent_gen_entropy(ec);
|
||||
}
|
||||
|
||||
if (ec->data == ec->old_data)
|
||||
jent_panic("jitterentropy: Duplicate output detected\n");
|
||||
|
||||
ec->old_data = ec->data;
|
||||
}
|
||||
|
||||
/**
|
||||
* Entry function: Obtain entropy for the caller.
|
||||
*
|
||||
@ -425,17 +576,18 @@ static void jent_fips_test(struct rand_data *ec)
|
||||
* This function truncates the last 64 bit entropy value output to the exact
|
||||
* size specified by the caller.
|
||||
*
|
||||
* Input:
|
||||
* @ec Reference to entropy collector
|
||||
* @data pointer to buffer for storing random data -- buffer must already
|
||||
* exist
|
||||
* @len size of the buffer, specifying also the requested number of random
|
||||
* in bytes
|
||||
* @ec [in] Reference to entropy collector
|
||||
* @data [in] pointer to buffer for storing random data -- buffer must already
|
||||
* exist
|
||||
* @len [in] size of the buffer, specifying also the requested number of random
|
||||
* in bytes
|
||||
*
|
||||
* @return 0 when request is fulfilled or an error
|
||||
*
|
||||
* The following error codes can occur:
|
||||
* -1 entropy_collector is NULL
|
||||
* -2 RCT failed
|
||||
* -3 APT test failed
|
||||
*/
|
||||
int jent_read_entropy(struct rand_data *ec, unsigned char *data,
|
||||
unsigned int len)
|
||||
@ -449,7 +601,42 @@ int jent_read_entropy(struct rand_data *ec, unsigned char *data,
|
||||
unsigned int tocopy;
|
||||
|
||||
jent_gen_entropy(ec);
|
||||
jent_fips_test(ec);
|
||||
|
||||
if (jent_health_failure(ec)) {
|
||||
int ret;
|
||||
|
||||
if (jent_rct_failure(ec))
|
||||
ret = -2;
|
||||
else
|
||||
ret = -3;
|
||||
|
||||
/*
|
||||
* Re-initialize the noise source
|
||||
*
|
||||
* If the health test fails, the Jitter RNG remains
|
||||
* in failure state and will return a health failure
|
||||
* during next invocation.
|
||||
*/
|
||||
if (jent_entropy_init())
|
||||
return ret;
|
||||
|
||||
/* Set APT to initial state */
|
||||
jent_apt_reset(ec, 0);
|
||||
ec->apt_base_set = 0;
|
||||
|
||||
/* Set RCT to initial state */
|
||||
ec->rct_count = 0;
|
||||
|
||||
/* Re-enable Jitter RNG */
|
||||
ec->health_failure = 0;
|
||||
|
||||
/*
|
||||
* Return the health test failure status to the
|
||||
* caller as the generated value is not appropriate.
|
||||
*/
|
||||
return ret;
|
||||
}
|
||||
|
||||
if ((DATA_SIZE_BITS / 8) < len)
|
||||
tocopy = (DATA_SIZE_BITS / 8);
|
||||
else
|
||||
@ -513,11 +700,15 @@ int jent_entropy_init(void)
|
||||
int i;
|
||||
__u64 delta_sum = 0;
|
||||
__u64 old_delta = 0;
|
||||
unsigned int nonstuck = 0;
|
||||
int time_backwards = 0;
|
||||
int count_mod = 0;
|
||||
int count_stuck = 0;
|
||||
struct rand_data ec = { 0 };
|
||||
|
||||
/* Required for RCT */
|
||||
ec.osr = 1;
|
||||
|
||||
/* We could perform statistical tests here, but the problem is
|
||||
* that we only have a few loop counts to do testing. These
|
||||
* loop counts may show some slight skew and we produce
|
||||
@ -539,8 +730,10 @@ int jent_entropy_init(void)
|
||||
/*
|
||||
* TESTLOOPCOUNT needs some loops to identify edge systems. 100 is
|
||||
* definitely too little.
|
||||
*
|
||||
* SP800-90B requires at least 1024 initial test cycles.
|
||||
*/
|
||||
#define TESTLOOPCOUNT 300
|
||||
#define TESTLOOPCOUNT 1024
|
||||
#define CLEARCACHE 100
|
||||
for (i = 0; (TESTLOOPCOUNT + CLEARCACHE) > i; i++) {
|
||||
__u64 time = 0;
|
||||
@ -552,13 +745,13 @@ int jent_entropy_init(void)
|
||||
/* Invoke core entropy collection logic */
|
||||
jent_get_nstime(&time);
|
||||
ec.prev_time = time;
|
||||
jent_lfsr_time(&ec, time, 0);
|
||||
jent_lfsr_time(&ec, time, 0, 0);
|
||||
jent_get_nstime(&time2);
|
||||
|
||||
/* test whether timer works */
|
||||
if (!time || !time2)
|
||||
return JENT_ENOTIME;
|
||||
delta = time2 - time;
|
||||
delta = jent_delta(time, time2);
|
||||
/*
|
||||
* test whether timer is fine grained enough to provide
|
||||
* delta even when called shortly after each other -- this
|
||||
@ -581,6 +774,28 @@ int jent_entropy_init(void)
|
||||
|
||||
if (stuck)
|
||||
count_stuck++;
|
||||
else {
|
||||
nonstuck++;
|
||||
|
||||
/*
|
||||
* Ensure that the APT succeeded.
|
||||
*
|
||||
* With the check below that count_stuck must be less
|
||||
* than 10% of the overall generated raw entropy values
|
||||
* it is guaranteed that the APT is invoked at
|
||||
* floor((TESTLOOPCOUNT * 0.9) / 64) == 14 times.
|
||||
*/
|
||||
if ((nonstuck % JENT_APT_WINDOW_SIZE) == 0) {
|
||||
jent_apt_reset(&ec,
|
||||
delta & JENT_APT_WORD_MASK);
|
||||
if (jent_health_failure(&ec))
|
||||
return JENT_EHEALTH;
|
||||
}
|
||||
}
|
||||
|
||||
/* Validate RCT */
|
||||
if (jent_rct_failure(&ec))
|
||||
return JENT_ERCT;
|
||||
|
||||
/* test whether we have an increasing timer */
|
||||
if (!(time2 > time))
|
||||
|
||||
Loading…
Reference in New Issue
Block a user