diff options
Diffstat (limited to 'crypto/drbg.c')
-rw-r--r-- | crypto/drbg.c | 234 |
1 files changed, 156 insertions, 78 deletions
diff --git a/crypto/drbg.c b/crypto/drbg.c index bc52d9562611..0df8cc9bb563 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -220,6 +220,57 @@ static inline unsigned short drbg_sec_strength(drbg_flag_t flags) } /* + * FIPS 140-2 continuous self test for the noise source + * The test is performed on the noise source input data. Thus, the function + * implicitly knows the size of the buffer to be equal to the security + * strength. + * + * Note, this function disregards the nonce trailing the entropy data during + * initial seeding. + * + * drbg->drbg_mutex must have been taken. + * + * @drbg DRBG handle + * @entropy buffer of seed data to be checked + * + * return: + * 0 on success + * -EAGAIN on when the CTRNG is not yet primed + * < 0 on error + */ +static int drbg_fips_continuous_test(struct drbg_state *drbg, + const unsigned char *entropy) +{ + unsigned short entropylen = drbg_sec_strength(drbg->core->flags); + int ret = 0; + + if (!IS_ENABLED(CONFIG_CRYPTO_FIPS)) + return 0; + + /* skip test if we test the overall system */ + if (list_empty(&drbg->test_data.list)) + return 0; + /* only perform test in FIPS mode */ + if (!fips_enabled) + return 0; + + if (!drbg->fips_primed) { + /* Priming of FIPS test */ + memcpy(drbg->prev, entropy, entropylen); + drbg->fips_primed = true; + /* priming: another round is needed */ + return -EAGAIN; + } + ret = memcmp(drbg->prev, entropy, entropylen); + if (!ret) + panic("DRBG continuous self test failed\n"); + memcpy(drbg->prev, entropy, entropylen); + + /* the test shall pass when the two values are not equal */ + return 0; +} + +/* * Convert an integer into a byte representation of this integer. * The byte representation is big-endian * @@ -984,55 +1035,79 @@ static const struct drbg_state_ops drbg_hash_ops = { ******************************************************************/ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, - int reseed) + int reseed, enum drbg_seed_state new_seed_state) { int ret = drbg->d_ops->update(drbg, seed, reseed); if (ret) return ret; - drbg->seeded = true; + drbg->seeded = new_seed_state; /* 10.1.1.2 / 10.1.1.3 step 5 */ drbg->reseed_ctr = 1; + switch (drbg->seeded) { + case DRBG_SEED_STATE_UNSEEDED: + /* Impossible, but handle it to silence compiler warnings. */ + case DRBG_SEED_STATE_PARTIAL: + /* + * Require frequent reseeds until the seed source is + * fully initialized. + */ + drbg->reseed_threshold = 50; + break; + + case DRBG_SEED_STATE_FULL: + /* + * Seed source has become fully initialized, frequent + * reseeds no longer required. + */ + drbg->reseed_threshold = drbg_max_requests(drbg); + break; + } + return ret; } -static void drbg_async_seed(struct work_struct *work) +static inline int drbg_get_random_bytes(struct drbg_state *drbg, + unsigned char *entropy, + unsigned int entropylen) +{ + int ret; + + do { + get_random_bytes(entropy, entropylen); + ret = drbg_fips_continuous_test(drbg, entropy); + if (ret && ret != -EAGAIN) + return ret; + } while (ret); + + return 0; +} + +static int drbg_seed_from_random(struct drbg_state *drbg) { struct drbg_string data; LIST_HEAD(seedlist); - struct drbg_state *drbg = container_of(work, struct drbg_state, - seed_work); unsigned int entropylen = drbg_sec_strength(drbg->core->flags); unsigned char entropy[32]; + int ret; BUG_ON(!entropylen); BUG_ON(entropylen > sizeof(entropy)); - get_random_bytes(entropy, entropylen); drbg_string_fill(&data, entropy, entropylen); list_add_tail(&data.list, &seedlist); - mutex_lock(&drbg->drbg_mutex); - - /* If nonblocking pool is initialized, deactivate Jitter RNG */ - crypto_free_rng(drbg->jent); - drbg->jent = NULL; - - /* Set seeded to false so that if __drbg_seed fails the - * next generate call will trigger a reseed. - */ - drbg->seeded = false; - - __drbg_seed(drbg, &seedlist, true); - - if (drbg->seeded) - drbg->reseed_threshold = drbg_max_requests(drbg); + ret = drbg_get_random_bytes(drbg, entropy, entropylen); + if (ret) + goto out; - mutex_unlock(&drbg->drbg_mutex); + ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL); +out: memzero_explicit(entropy, entropylen); + return ret; } /* @@ -1054,6 +1129,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, unsigned int entropylen = drbg_sec_strength(drbg->core->flags); struct drbg_string data1; LIST_HEAD(seedlist); + enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL; /* 9.1 / 9.2 / 9.3.1 step 3 */ if (pers && pers->len > (drbg_max_addtl(drbg))) { @@ -1081,7 +1157,12 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, BUG_ON((entropylen * 2) > sizeof(entropy)); /* Get seed from in-kernel /dev/urandom */ - get_random_bytes(entropy, entropylen); + if (!rng_is_initialized()) + new_seed_state = DRBG_SEED_STATE_PARTIAL; + + ret = drbg_get_random_bytes(drbg, entropy, entropylen); + if (ret) + goto out; if (!drbg->jent) { drbg_string_fill(&data1, entropy, entropylen); @@ -1094,7 +1175,23 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, entropylen); if (ret) { pr_devel("DRBG: jent failed with %d\n", ret); - return ret; + + /* + * Do not treat the transient failure of the + * Jitter RNG as an error that needs to be + * reported. The combined number of the + * maximum reseed threshold times the maximum + * number of Jitter RNG transient errors is + * less than the reseed threshold required by + * SP800-90A allowing us to treat the + * transient errors as such. + * + * However, we mandate that at least the first + * seeding operation must succeed with the + * Jitter RNG. + */ + if (!reseed || ret != -EAGAIN) + goto out; } drbg_string_fill(&data1, entropy, entropylen * 2); @@ -1119,8 +1216,9 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, memset(drbg->C, 0, drbg_statelen(drbg)); } - ret = __drbg_seed(drbg, &seedlist, reseed); + ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state); +out: memzero_explicit(entropy, entropylen * 2); return ret; @@ -1142,6 +1240,11 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg) drbg->reseed_ctr = 0; drbg->d_ops = NULL; drbg->core = NULL; + if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) { + kzfree(drbg->prev); + drbg->prev = NULL; + drbg->fips_primed = false; + } } /* @@ -1211,6 +1314,14 @@ static inline int drbg_alloc_state(struct drbg_state *drbg) drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1); } + if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) { + drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags), + GFP_KERNEL); + if (!drbg->prev) + goto fini; + drbg->fips_primed = false; + } + return 0; fini: @@ -1283,19 +1394,25 @@ static int drbg_generate(struct drbg_state *drbg, * here. The spec is a bit convoluted here, we make it simpler. */ if (drbg->reseed_threshold < drbg->reseed_ctr) - drbg->seeded = false; + drbg->seeded = DRBG_SEED_STATE_UNSEEDED; - if (drbg->pr || !drbg->seeded) { + if (drbg->pr || drbg->seeded == DRBG_SEED_STATE_UNSEEDED) { pr_devel("DRBG: reseeding before generation (prediction " "resistance: %s, state %s)\n", drbg->pr ? "true" : "false", - drbg->seeded ? "seeded" : "unseeded"); + (drbg->seeded == DRBG_SEED_STATE_FULL ? + "seeded" : "unseeded")); /* 9.3.1 steps 7.1 through 7.3 */ len = drbg_seed(drbg, addtl, true); if (len) goto err; /* 9.3.1 step 7.4 */ addtl = NULL; + } else if (rng_is_initialized() && + drbg->seeded == DRBG_SEED_STATE_PARTIAL) { + len = drbg_seed_from_random(drbg); + if (len) + goto err; } if (addtl && 0 < addtl->len) @@ -1388,51 +1505,23 @@ static int drbg_generate_long(struct drbg_state *drbg, return 0; } -static void drbg_schedule_async_seed(struct random_ready_callback *rdy) -{ - struct drbg_state *drbg = container_of(rdy, struct drbg_state, - random_ready); - - schedule_work(&drbg->seed_work); -} - static int drbg_prepare_hrng(struct drbg_state *drbg) { - int err; - /* We do not need an HRNG in test mode. */ if (list_empty(&drbg->test_data.list)) return 0; - INIT_WORK(&drbg->seed_work, drbg_async_seed); - - drbg->random_ready.owner = THIS_MODULE; - drbg->random_ready.func = drbg_schedule_async_seed; - - err = add_random_ready_callback(&drbg->random_ready); - - switch (err) { - case 0: - break; - - case -EALREADY: - err = 0; - /* fall through */ - - default: - drbg->random_ready.func = NULL; - return err; - } - drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0); + if (IS_ERR(drbg->jent)) { + const int err = PTR_ERR(drbg->jent); - /* - * Require frequent reseeds until the seed source is fully - * initialized. - */ - drbg->reseed_threshold = 50; + drbg->jent = NULL; + if (fips_enabled) + return err; + pr_info("DRBG: Continuing without Jitter RNG\n"); + } - return err; + return 0; } /* @@ -1475,7 +1564,7 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, if (!drbg->core) { drbg->core = &drbg_cores[coreref]; drbg->pr = pr; - drbg->seeded = false; + drbg->seeded = DRBG_SEED_STATE_UNSEEDED; drbg->reseed_threshold = drbg_max_requests(drbg); ret = drbg_alloc_state(drbg); @@ -1486,14 +1575,6 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, if (ret) goto free_everything; - if (IS_ERR(drbg->jent)) { - ret = PTR_ERR(drbg->jent); - drbg->jent = NULL; - if (fips_enabled || ret != -ENOENT) - goto free_everything; - pr_info("DRBG: Continuing without Jitter RNG\n"); - } - reseed = false; } @@ -1526,12 +1607,9 @@ free_everything: */ static int drbg_uninstantiate(struct drbg_state *drbg) { - if (drbg->random_ready.func) { - del_random_ready_callback(&drbg->random_ready); - cancel_work_sync(&drbg->seed_work); + if (!IS_ERR_OR_NULL(drbg->jent)) crypto_free_rng(drbg->jent); - drbg->jent = NULL; - } + drbg->jent = NULL; if (drbg->d_ops) drbg->d_ops->crypto_fini(drbg); |