From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/crypto/jitterentropy.c | 723 +++++++++++++++++++++++++++++++------------------------
1 files changed, 405 insertions(+), 318 deletions(-)
diff --git a/kernel/crypto/jitterentropy.c b/kernel/crypto/jitterentropy.c
index acf44b2..423c55d 100644
--- a/kernel/crypto/jitterentropy.c
+++ b/kernel/crypto/jitterentropy.c
@@ -2,12 +2,12 @@
* Non-physical true random number generator based on timing jitter --
* Jitter RNG standalone code.
*
- * Copyright Stephan Mueller <smueller@chronox.de>, 2015
+ * Copyright Stephan Mueller <smueller@chronox.de>, 2015 - 2020
*
* Design
* ======
*
- * See http://www.chronox.de/jent.html
+ * See https://www.chronox.de/jent.html
*
* License
* =======
@@ -47,7 +47,7 @@
/*
* This Jitterentropy RNG is based on the jitterentropy library
- * version 1.1.0 provided at http://www.chronox.de/jent.html
+ * version 2.2.0 provided at https://www.chronox.de/jent.html
*/
#ifdef __OPTIMIZE__
@@ -71,10 +71,7 @@
#define DATA_SIZE_BITS ((sizeof(__u64)) * 8)
__u64 last_delta; /* SENSITIVE stuck test */
__s64 last_delta2; /* SENSITIVE stuck test */
- unsigned int stuck:1; /* Time measurement stuck */
unsigned int osr; /* Oversample rate */
- unsigned int stir:1; /* Post-processing stirring */
- unsigned int disable_unbias:1; /* Deactivate Von-Neuman unbias */
#define JENT_MEMORY_BLOCKS 64
#define JENT_MEMORY_BLOCKSIZE 32
#define JENT_MEMORY_ACCESSLOOPS 128
@@ -86,11 +83,25 @@
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 */
-#define JENT_DISABLE_STIR (1<<0) /* Disable stirring the entropy pool */
-#define JENT_DISABLE_UNBIAS (1<<1) /* Disable the Von-Neuman Unbiaser */
#define JENT_DISABLE_MEMORY_ACCESS (1<<2) /* Disable memory access for more
* entropy, saves MEMORY_SIZE RAM for
* entropy collector */
@@ -99,24 +110,220 @@
#define JENT_ENOTIME 1 /* Timer service not available */
#define JENT_ECOARSETIME 2 /* Timer too coarse for RNG */
#define JENT_ENOMONOTONIC 3 /* Timer is not monotonic increasing */
-#define JENT_EMINVARIATION 4 /* Timer variations too small for RNG */
#define JENT_EVARVAR 5 /* Timer does not produce variations of
* variations (2nd derivation of time is
* zero). */
-#define JENT_EMINVARVAR 6 /* Timer variations of variations is tooi
- * small. */
+#define JENT_ESTUCK 8 /* Too many stuck results during init. */
+#define JENT_EHEALTH 9 /* Health test failed during initialization */
+#define JENT_ERCT 10 /* RCT failed during initialization */
+
+/*
+ * The output n bits can receive more than n bits of min entropy, of course,
+ * but the fixed output of the conditioning function can only asymptotically
+ * approach the output size bits of min entropy, not attain that bound. Random
+ * maps will tend to have output collisions, which reduces the creditable
+ * output entropy (that is what SP 800-90B Section 3.1.5.1.2 attempts to bound).
+ *
+ * The value "64" is justified in Appendix A.4 of the current 90C draft,
+ * and aligns with NIST's in "epsilon" definition in this document, which is
+ * that a string can be considered "full entropy" if you can bound the min
+ * entropy in each bit of output to at least 1-epsilon, where epsilon is
+ * required to be <= 2^(-32).
+ */
+#define JENT_ENTROPY_SAFETY_FACTOR 64
+
+#include <linux/fips.h>
+#include "jitterentropy.h"
/***************************************************************************
- * Helper functions
+ * Adaptive Proportion Test
+ *
+ * This test complies with SP800-90B section 4.4.2.
***************************************************************************/
-void jent_get_nstime(__u64 *out);
-__u64 jent_rol64(__u64 word, unsigned int shift);
-void *jent_zalloc(unsigned int len);
-void jent_zfree(void *ptr);
-int jent_fips_enabled(void);
-void jent_panic(char *s);
-void jent_memcpy(void *dest, const void *src, unsigned int n);
+/**
+ * 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);
+
+ 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, current_delta);
+
+ 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
@@ -140,16 +347,16 @@
jent_get_nstime(&time);
/*
- * mix the current state of the random number into the shuffle
- * calculation to balance that shuffle a bit more
+ * Mix the current state of the random number into the shuffle
+ * calculation to balance that shuffle a bit more.
*/
if (ec)
time ^= ec->data;
/*
- * we fold the time value as much as possible to ensure that as many
- * bits of the time stamp are included as possible
+ * We fold the time value as much as possible to ensure that as many
+ * bits of the time stamp are included as possible.
*/
- for (i = 0; (DATA_SIZE_BITS / bits) > i; i++) {
+ for (i = 0; ((DATA_SIZE_BITS + bits - 1) / bits) > i; i++) {
shuffle ^= time & mask;
time = time >> bits;
}
@@ -161,46 +368,33 @@
return (shuffle + (1<<min));
}
-/***************************************************************************
- * Noise sources
- ***************************************************************************/
-
/**
* CPU Jitter noise source -- this is the noise source based on the CPU
* execution time jitter
*
- * This function folds the time into one bit units by iterating
- * through the DATA_SIZE_BITS bit time value as follows: assume our time value
- * is 0xabcd
- * 1st loop, 1st shift generates 0xd000
- * 1st loop, 2nd shift generates 0x000d
- * 2nd loop, 1st shift generates 0xcd00
- * 2nd loop, 2nd shift generates 0x000c
- * 3rd loop, 1st shift generates 0xbcd0
- * 3rd loop, 2nd shift generates 0x000b
- * 4th loop, 1st shift generates 0xabcd
- * 4th loop, 2nd shift generates 0x000a
- * Now, the values at the end of the 2nd shifts are XORed together.
+ * This function injects the individual bits of the time value into the
+ * entropy pool using an LFSR.
*
- * The code is deliberately inefficient and shall stay that way. This function
- * is the root cause why the code shall be compiled without optimization. This
- * function not only acts as folding operation, but this function's execution
- * is used to measure the CPU execution time jitter. Any change to the loop in
- * this function implies that careful retesting must be done.
+ * The code is deliberately inefficient with respect to the bit shifting
+ * and shall stay that way. This function is the root cause why the code
+ * shall be compiled without optimization. This function not only acts as
+ * folding operation, but this function's execution is used to measure
+ * 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 -- may be NULL
- * @time time stamp to be folded
- * @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:
- * @folded result of folding operation
+ * updated ec->data
*
* @return Number of loops the folding operation is performed
*/
-static __u64 jent_fold_time(struct rand_data *ec, __u64 time,
- __u64 *folded, __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;
@@ -217,16 +411,43 @@
if (loop_cnt)
fold_loop_cnt = loop_cnt;
for (j = 0; j < fold_loop_cnt; j++) {
- new = 0;
+ new = ec->data;
for (i = 1; (DATA_SIZE_BITS) >= i; i++) {
__u64 tmp = time << (DATA_SIZE_BITS - i);
tmp = tmp >> (DATA_SIZE_BITS - 1);
+
+ /*
+ * Fibonacci LSFR with polynomial of
+ * x^64 + x^61 + x^56 + x^31 + x^28 + x^23 + 1 which is
+ * primitive according to
+ * http://poincare.matf.bg.ac.rs/~ezivkovm/publications/primpol1.pdf
+ * (the shift values are the polynomial values minus one
+ * due to counting bits from 0 to 63). As the current
+ * position is always the LSB, the polynomial only needs
+ * to shift data in from the left without wrap.
+ */
+ tmp ^= ((new >> 63) & 1);
+ tmp ^= ((new >> 60) & 1);
+ tmp ^= ((new >> 55) & 1);
+ tmp ^= ((new >> 30) & 1);
+ tmp ^= ((new >> 27) & 1);
+ tmp ^= ((new >> 22) & 1);
+ new <<= 1;
new ^= tmp;
}
}
- *folded = 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;
}
/**
@@ -247,18 +468,14 @@
* 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 char *tmpval = NULL;
unsigned int wrap = 0;
__u64 i = 0;
#define MAX_ACC_LOOP_BIT 7
@@ -267,7 +484,7 @@
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;
/*
@@ -278,7 +495,7 @@
acc_loop_cnt = loop_cnt;
for (i = 0; i < (ec->memaccessloops + acc_loop_cnt); i++) {
- tmpval = ec->mem + ec->memlocation;
+ unsigned char *tmpval = ec->mem + ec->memlocation;
/*
* memory access: just add 1 to one byte,
* wrap at 255 -- memory access implies read
@@ -293,61 +510,29 @@
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 void 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)
- ec->stuck = 1;
-}
-
/**
* This is the heart of the entropy generation: calculate time deltas and
- * use the CPU jitter in the time deltas. The jitter is folded into one
- * bit. You can call this function the "random bit generator" as it
- * produces one random bit per invocation.
+ * use the CPU jitter in the time deltas. The jitter is injected into the
+ * entropy pool.
*
* WARNING: ensure that ->prev_time is primed before using the output
* 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 One random bit
+ * @return result of stuck test
*/
-static __u64 jent_measure_jitter(struct rand_data *ec)
+static int jent_measure_jitter(struct rand_data *ec)
{
__u64 time = 0;
- __u64 data = 0;
__u64 current_delta = 0;
+ int stuck;
/* Invoke one noise source before time measurement to add variations */
jent_memaccess(ec, 0);
@@ -357,206 +542,46 @@
* 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 folds the data */
- jent_fold_time(ec, current_delta, &data, 0);
+ /* Check whether we have a stuck measurement. */
+ stuck = jent_stuck(ec, current_delta);
- /*
- * Check whether we have a stuck measurement. The enforcement
- * is performed after the stuck value has been mixed into the
- * entropy pool.
- */
- 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 data;
-}
-
-/**
- * Von Neuman unbias as explained in RFC 4086 section 4.2. As shown in the
- * documentation of that RNG, the bits from jent_measure_jitter are considered
- * independent which implies that the Von Neuman unbias operation is applicable.
- * A proof of the Von-Neumann unbias operation to remove skews is given in the
- * document "A proposal for: Functionality classes for random number
- * generators", version 2.0 by Werner Schindler, section 5.4.1.
- *
- * Input:
- * @entropy_collector Reference to entropy collector
- *
- * @return One random bit
- */
-static __u64 jent_unbiased_bit(struct rand_data *entropy_collector)
-{
- do {
- __u64 a = jent_measure_jitter(entropy_collector);
- __u64 b = jent_measure_jitter(entropy_collector);
-
- if (a == b)
- continue;
- if (1 == a)
- return 1;
- else
- return 0;
- } while (1);
-}
-
-/**
- * Shuffle the pool a bit by mixing some value with a bijective function (XOR)
- * into the pool.
- *
- * The function generates a mixer value that depends on the bits set and the
- * location of the set bits in the random number generated by the entropy
- * source. Therefore, based on the generated random number, this mixer value
- * can have 2**64 different values. That mixer value is initialized with the
- * first two SHA-1 constants. After obtaining the mixer value, it is XORed into
- * the random number.
- *
- * The mixer value is not assumed to contain any entropy. But due to the XOR
- * operation, it can also not destroy any entropy present in the entropy pool.
- *
- * Input:
- * @entropy_collector Reference to entropy collector
- */
-static void jent_stir_pool(struct rand_data *entropy_collector)
-{
- /*
- * to shut up GCC on 32 bit, we have to initialize the 64 variable
- * with two 32 bit variables
- */
- union c {
- __u64 u64;
- __u32 u32[2];
- };
- /*
- * This constant is derived from the first two 32 bit initialization
- * vectors of SHA-1 as defined in FIPS 180-4 section 5.3.1
- */
- union c constant;
- /*
- * The start value of the mixer variable is derived from the third
- * and fourth 32 bit initialization vector of SHA-1 as defined in
- * FIPS 180-4 section 5.3.1
- */
- union c mixer;
- unsigned int i = 0;
-
- /*
- * Store the SHA-1 constants in reverse order to make up the 64 bit
- * value -- this applies to a little endian system, on a big endian
- * system, it reverses as expected. But this really does not matter
- * as we do not rely on the specific numbers. We just pick the SHA-1
- * constants as they have a good mix of bit set and unset.
- */
- constant.u32[1] = 0x67452301;
- constant.u32[0] = 0xefcdab89;
- mixer.u32[1] = 0x98badcfe;
- mixer.u32[0] = 0x10325476;
-
- for (i = 0; i < DATA_SIZE_BITS; i++) {
- /*
- * get the i-th bit of the input random number and only XOR
- * the constant into the mixer value when that bit is set
- */
- if ((entropy_collector->data >> i) & 1)
- mixer.u64 ^= constant.u64;
- mixer.u64 = jent_rol64(mixer.u64, 1);
- }
- entropy_collector->data ^= mixer.u64;
+ 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)
{
- unsigned int k = 0;
+ unsigned int k = 0, safety_factor = 0;
+
+ if (fips_enabled)
+ safety_factor = JENT_ENTROPY_SAFETY_FACTOR;
/* priming of the ->prev_time value */
jent_measure_jitter(ec);
while (1) {
- __u64 data = 0;
-
- if (ec->disable_unbias == 1)
- data = jent_measure_jitter(ec);
- else
- data = jent_unbiased_bit(ec);
-
- /* enforcement of the jent_stuck test */
- if (ec->stuck) {
- /*
- * We only mix in the bit considered not appropriate
- * without the LSFR. The reason is that if we apply
- * the LSFR and we do not rotate, the 2nd bit with LSFR
- * will cancel out the first LSFR application on the
- * bad bit.
- *
- * And we do not rotate as we apply the next bit to the
- * current bit location again.
- */
- ec->data ^= data;
- ec->stuck = 0;
+ /* If a stuck measurement is received, repeat measurement */
+ if (jent_measure_jitter(ec))
continue;
- }
-
- /*
- * Fibonacci LSFR with polynom of
- * x^64 + x^61 + x^56 + x^31 + x^28 + x^23 + 1 which is
- * primitive according to
- * http://poincare.matf.bg.ac.rs/~ezivkovm/publications/primpol1.pdf
- * (the shift values are the polynom values minus one
- * due to counting bits from 0 to 63). As the current
- * position is always the LSB, the polynom only needs
- * to shift data in from the left without wrap.
- */
- ec->data ^= data;
- ec->data ^= ((ec->data >> 63) & 1);
- ec->data ^= ((ec->data >> 60) & 1);
- ec->data ^= ((ec->data >> 55) & 1);
- ec->data ^= ((ec->data >> 30) & 1);
- ec->data ^= ((ec->data >> 27) & 1);
- ec->data ^= ((ec->data >> 22) & 1);
- ec->data = jent_rol64(ec->data, 1);
/*
* We multiply the loop value with ->osr to obtain the
* oversampling rate requested by the caller
*/
- if (++k >= (DATA_SIZE_BITS * ec->osr))
+ if (++k >= ((DATA_SIZE_BITS + safety_factor) * ec->osr))
break;
}
- if (ec->stir)
- jent_stir_pool(ec);
-}
-
-/**
- * The continuous test required by FIPS 140-2 -- the function automatically
- * primes the test if needed.
- *
- * Return:
- * 0 if FIPS test passed
- * < 0 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;
}
/**
@@ -569,17 +594,18 @@
* 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)
@@ -593,7 +619,42 @@
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
@@ -639,12 +700,6 @@
osr = 1; /* minimum sampling rate is 1 */
entropy_collector->osr = osr;
- entropy_collector->stir = 1;
- if (flags & JENT_DISABLE_STIR)
- entropy_collector->stir = 0;
- if (flags & JENT_DISABLE_UNBIAS)
- entropy_collector->disable_unbias = 1;
-
/* fill the data pad with non-zero values */
jent_gen_entropy(entropy_collector);
@@ -656,7 +711,6 @@
jent_zfree(entropy_collector->mem);
entropy_collector->mem = NULL;
jent_zfree(entropy_collector);
- entropy_collector = NULL;
}
int jent_entropy_init(void)
@@ -664,9 +718,14 @@
int i;
__u64 delta_sum = 0;
__u64 old_delta = 0;
+ unsigned int nonstuck = 0;
int time_backwards = 0;
- int count_var = 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
@@ -689,24 +748,28 @@
/*
* 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;
__u64 time2 = 0;
- __u64 folded = 0;
__u64 delta = 0;
unsigned int lowdelta = 0;
+ int stuck;
+ /* Invoke core entropy collection logic */
jent_get_nstime(&time);
- jent_fold_time(NULL, time, &folded, 1<<MIN_FOLD_LOOP_BIT);
+ ec.prev_time = time;
+ 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
@@ -714,6 +777,8 @@
*/
if (!delta)
return JENT_ECOARSETIME;
+
+ stuck = jent_stuck(&ec, delta);
/*
* up to here we did not modify any variable that will be
@@ -725,14 +790,36 @@
if (CLEARCACHE > i)
continue;
+ 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))
time_backwards++;
- /*
- * Avoid modulo of 64 bit integer to allow code to compile
- * on 32 bit architectures.
- */
+ /* use 32 bit value to ensure compilation on 32 bit arches */
lowdelta = time2 - time;
if (!(lowdelta % 100))
count_mod++;
@@ -743,14 +830,10 @@
* only after the first loop is executed as we need to prime
* the old_data value
*/
- if (i) {
- if (delta != old_delta)
- count_var++;
- if (delta > old_delta)
- delta_sum += (delta - old_delta);
- else
- delta_sum += (old_delta - delta);
- }
+ if (delta > old_delta)
+ delta_sum += (delta - old_delta);
+ else
+ delta_sum += (old_delta - delta);
old_delta = delta;
}
@@ -763,25 +846,29 @@
*/
if (3 < time_backwards)
return JENT_ENOMONOTONIC;
- /* Error if the time variances are always identical */
- if (!delta_sum)
- return JENT_EVARVAR;
/*
* Variations of deltas of time must on average be larger
* than 1 to ensure the entropy estimation
* implied with 1 is preserved
*/
- if (delta_sum <= 1)
- return JENT_EMINVARVAR;
+ if ((delta_sum) <= 1)
+ return JENT_EVARVAR;
/*
* Ensure that we have variations in the time stamp below 10 for at
- * least 10% of all checks -- on some platforms, the counter
- * increments in multiples of 100, but not always
+ * least 10% of all checks -- on some platforms, the counter increments
+ * in multiples of 100, but not always
*/
if ((TESTLOOPCOUNT/10 * 9) < count_mod)
return JENT_ECOARSETIME;
+ /*
+ * If we have more than 90% stuck results, then this Jitter RNG is
+ * likely to not work well.
+ */
+ if ((TESTLOOPCOUNT/10 * 9) < count_stuck)
+ return JENT_ESTUCK;
+
return 0;
}
--
Gitblit v1.6.2