diff options
| -rw-r--r-- | crypto/jitterentropy.c | 125 |
1 files changed, 74 insertions, 51 deletions
diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c index 09c9db90c154..26a9048bc893 100644 --- a/crypto/jitterentropy.c +++ b/crypto/jitterentropy.c @@ -100,6 +100,8 @@ struct rand_data { unsigned int apt_observations; /* Number of collected observations */ unsigned int apt_count; /* APT counter */ unsigned int apt_base; /* APT base reference */ + unsigned int health_failure; /* Record health failure */ + unsigned int apt_base_set:1; /* APT base reference set? */ }; @@ -121,6 +123,13 @@ struct rand_data { #define JENT_EHASH 11 /* Hash self test failed */ #define JENT_EMEM 12 /* Can't allocate memory for initialization */ +#define JENT_RCT_FAILURE 1 /* Failure in RCT health test. */ +#define JENT_APT_FAILURE 2 /* Failure in APT health test. */ +#define JENT_PERMANENT_FAILURE_SHIFT 16 +#define JENT_PERMANENT_FAILURE(x) (x << JENT_PERMANENT_FAILURE_SHIFT) +#define JENT_RCT_FAILURE_PERMANENT JENT_PERMANENT_FAILURE(JENT_RCT_FAILURE) +#define JENT_APT_FAILURE_PERMANENT JENT_PERMANENT_FAILURE(JENT_APT_FAILURE) + /* * 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 @@ -215,26 +224,22 @@ static void jent_apt_insert(struct rand_data *ec, unsigned int delta_masked) return; } - if (delta_masked == ec->apt_base) + if (delta_masked == ec->apt_base) { ec->apt_count++; + /* Note, ec->apt_count starts with one. */ + if (ec->apt_count >= ec->apt_cutoff_permanent) + ec->health_failure |= JENT_APT_FAILURE_PERMANENT; + else if (ec->apt_count >= ec->apt_cutoff) + ec->health_failure |= JENT_APT_FAILURE; + } + ec->apt_observations++; if (ec->apt_observations >= JENT_APT_WINDOW_SIZE) jent_apt_reset(ec, delta_masked); } -/* APT health test failure detection */ -static int jent_apt_permanent_failure(struct rand_data *ec) -{ - return (ec->apt_count >= ec->apt_cutoff_permanent) ? 1 : 0; -} - -static int jent_apt_failure(struct rand_data *ec) -{ - return (ec->apt_count >= ec->apt_cutoff) ? 1 : 0; -} - /*************************************************************************** * Stuck Test and its use as Repetition Count Test * @@ -261,6 +266,30 @@ static void jent_rct_insert(struct rand_data *ec, int stuck) { if (stuck) { ec->rct_count++; + + /* + * The cutoff value is based on the following consideration: + * alpha = 2^-30 or 2^-60 as recommended in SP800-90B. + * 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 (DATA_SIZE_BITS + ENTROPY_SAFETY_FACTOR)*osr + * deltas for inserting them into the entropy pool which should + * then have (close to) DATA_SIZE_BITS bits of entropy in the + * conditioned output. + * + * 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. Thus C = ceil(-log_2(alpha)/H) = 30*osr + * or 60*osr. + */ + if ((unsigned int)ec->rct_count >= (60 * ec->osr)) { + ec->rct_count = -1; + ec->health_failure |= JENT_RCT_FAILURE_PERMANENT; + } else if ((unsigned int)ec->rct_count >= (30 * ec->osr)) { + ec->rct_count = -1; + ec->health_failure |= JENT_RCT_FAILURE; + } } else { /* Reset RCT */ ec->rct_count = 0; @@ -316,38 +345,24 @@ static int jent_stuck(struct rand_data *ec, __u64 current_delta) } /* - * The cutoff value is based on the following consideration: - * alpha = 2^-30 or 2^-60 as recommended in SP800-90B. - * 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 (DATA_SIZE_BITS + ENTROPY_SAFETY_FACTOR)*osr deltas for - * inserting them into the entropy pool which should then have (close to) - * DATA_SIZE_BITS bits of entropy in the conditioned output. - * - * 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. Thus - * C = ceil(-log_2(alpha)/H) = 30*osr or 60*osr. + * Report any health test failures + * + * @ec [in] Reference to entropy collector + * + * @return a bitmask indicating which tests failed + * 0 No health test failure + * 1 RCT failure + * 2 APT failure + * 1<<JENT_PERMANENT_FAILURE_SHIFT RCT permanent failure + * 2<<JENT_PERMANENT_FAILURE_SHIFT APT permanent failure */ -static int jent_rct_permanent_failure(struct rand_data *ec) +static unsigned int jent_health_failure(struct rand_data *ec) { - return (ec->rct_count >= (60 * ec->osr)) ? 1 : 0; -} + /* Test is only enabled in FIPS mode */ + if (!fips_enabled) + return 0; -static int jent_rct_failure(struct rand_data *ec) -{ - return (ec->rct_count >= (30 * ec->osr)) ? 1 : 0; -} - -/* Report of health test failures */ -static int jent_health_failure(struct rand_data *ec) -{ - return jent_rct_failure(ec) | jent_apt_failure(ec); -} - -static int jent_permanent_health_failure(struct rand_data *ec) -{ - return jent_rct_permanent_failure(ec) | jent_apt_permanent_failure(ec); + return ec->health_failure; } /*************************************************************************** @@ -594,11 +609,12 @@ int jent_read_entropy(struct rand_data *ec, unsigned char *data, return -1; while (len > 0) { - unsigned int tocopy; + unsigned int tocopy, health_test_result; jent_gen_entropy(ec); - if (jent_permanent_health_failure(ec)) { + health_test_result = jent_health_failure(ec); + if (health_test_result > JENT_PERMANENT_FAILURE_SHIFT) { /* * At this point, the Jitter RNG instance is considered * as a failed instance. There is no rerun of the @@ -606,13 +622,18 @@ int jent_read_entropy(struct rand_data *ec, unsigned char *data, * is assumed to not further use this instance. */ return -3; - } else if (jent_health_failure(ec)) { + } else if (health_test_result) { /* * Perform startup health tests and return permanent * error if it fails. */ - if (jent_entropy_init(0, 0, NULL, ec)) + if (jent_entropy_init(0, 0, NULL, ec)) { + /* Mark the permanent error */ + ec->health_failure &= + JENT_RCT_FAILURE_PERMANENT | + JENT_APT_FAILURE_PERMANENT; return -3; + } return -2; } @@ -695,6 +716,7 @@ int jent_entropy_init(unsigned int osr, unsigned int flags, void *hash_state, */ struct rand_data *ec = p_ec; int i, time_backwards = 0, ret = 0, ec_free = 0; + unsigned int health_test_result; if (!ec) { ec = jent_entropy_collector_alloc(osr, flags, hash_state); @@ -708,6 +730,9 @@ int jent_entropy_init(unsigned int osr, unsigned int flags, void *hash_state, ec->apt_base_set = 0; /* Reset the RCT */ ec->rct_count = 0; + /* Reset intermittent, leave permanent health test result */ + ec->health_failure &= (~JENT_RCT_FAILURE); + ec->health_failure &= (~JENT_APT_FAILURE); } /* We could perform statistical tests here, but the problem is @@ -788,12 +813,10 @@ int jent_entropy_init(unsigned int osr, unsigned int flags, void *hash_state, } /* Did we encounter a health test failure? */ - if (jent_rct_failure(ec)) { - ret = JENT_ERCT; - goto out; - } - if (jent_apt_failure(ec)) { - ret = JENT_EHEALTH; + health_test_result = jent_health_failure(ec); + if (health_test_result) { + ret = (health_test_result & JENT_RCT_FAILURE) ? JENT_ERCT : + JENT_EHEALTH; goto out; } |