Parts of the LRNG are already covered by self-tests, including: * Self-test of SP800-90A DRBG provided by the Linux kernel crypto API. * Self-test of the PRNG provided by the Linux kernel crypto API. * Raw noise source data testing including SP800-90B compliant tests when enabling CONFIG_LRNG_HEALTH_TESTS This patch adds the self-tests for the remaining critical functions of the LRNG that are essential to maintain entropy and provide cryptographic strong random numbers. The following self-tests are implemented: * Self-test of the time array maintenance. This test verifies whether the time stamp array management to store multiple values in one integer implements a concatenation of the data. * Self-test of the software hash implementation ensures that this function operates compliant to the FIPS 180-4 specification. The self-test performs a hash operation of a zeroized per-CPU data array. * Self-test of the ChaCha20 DRNG is based on the self-tests that are already present and implemented with the stand-alone user space ChaCha20 DRNG implementation available at [1]. The self-tests cover different use cases of the DRNG seeded with known seed data. The status of the LRNG self-tests is provided with the selftest_status SysFS file. If the file contains a zero, the self-tests passed. The value 0xffffffff means that the self-tests were not executed. Any other value indicates a self-test failure. The self-test may be compiled to panic the system if the self-test fails. All self-tests operate on private state data structures. This implies that none of the self-tests have any impact on the regular LRNG operations. This allows the self-tests to be repeated at runtime by writing anything into the selftest_status SysFS file. [1] https://www.chronox.de/chacha20.html CC: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> CC: "Alexander E. Patrakov" <patrakov@xxxxxxxxx> CC: "Ahmed S. Darwish" <darwish.07@xxxxxxxxx> CC: "Theodore Y. Ts'o" <tytso@xxxxxxx> CC: Willy Tarreau <w@xxxxxx> CC: Matthew Garrett <mjg59@xxxxxxxxxxxxx> CC: Vito Caputo <vcaputo@xxxxxxxxxxx> CC: Andreas Dilger <adilger.kernel@xxxxxxxxx> CC: Jan Kara <jack@xxxxxxx> CC: Ray Strode <rstrode@xxxxxxxxxx> CC: William Jon McCann <mccann@xxxxxxx> CC: zhangjs <zachary@xxxxxxxxxxxxxxxx> CC: Andy Lutomirski <luto@xxxxxxxxxx> CC: Florian Weimer <fweimer@xxxxxxxxxx> CC: Lennart Poettering <mzxreary@xxxxxxxxxxx> CC: Nicolai Stange <nstange@xxxxxxx> CC: Marcelo Henrique Cerri <marcelo.cerri@xxxxxxxxxxxxx> CC: Neil Horman <nhorman@xxxxxxxxxx> Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx> --- drivers/char/lrng/Kconfig | 26 +++ drivers/char/lrng/Makefile | 1 + drivers/char/lrng/lrng_selftest.c | 344 ++++++++++++++++++++++++++++++ 3 files changed, 371 insertions(+) create mode 100644 drivers/char/lrng/lrng_selftest.c diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig index bb785bc61abb..6f180641a5da 100644 --- a/drivers/char/lrng/Kconfig +++ b/drivers/char/lrng/Kconfig @@ -324,4 +324,30 @@ config LRNG_TESTING endif #LRNG_TESTING_MENU +config LRNG_SELFTEST + bool "Enable power-on and on-demand self-tests" + help + The power-on self-tests are executed during boot time + covering the ChaCha20 DRNG, the hash operation used for + processing the entropy pools and the auxiliary pool, and + the time stamp management of the LRNG. + + The on-demand self-tests are triggered by writing any + value into the SysFS file selftest_status. At the same + time, when reading this file, the test status is + returned. A zero indicates that all tests were executed + successfully. + + If unsure, say Y. + +if LRNG_SELFTEST + +config LRNG_SELFTEST_PANIC + bool "Panic the kernel upon self-test failure" + help + If the option is enabled, the kernel is terminated if an + LRNG power-on self-test failure is detected. + +endif # LRNG_SELFTEST + endif # LRNG diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile index 532501b38a00..a633638af991 100644 --- a/drivers/char/lrng/Makefile +++ b/drivers/char/lrng/Makefile @@ -17,3 +17,4 @@ obj-$(CONFIG_LRNG_KCAPI) += lrng_kcapi.o obj-$(CONFIG_LRNG_JENT) += lrng_jent.o obj-$(CONFIG_LRNG_HEALTH_TESTS) += lrng_health.o obj-$(CONFIG_LRNG_TESTING) += lrng_testing.o +obj-$(CONFIG_LRNG_SELFTEST) += lrng_selftest.o diff --git a/drivers/char/lrng/lrng_selftest.c b/drivers/char/lrng/lrng_selftest.c new file mode 100644 index 000000000000..4c7d124d24a4 --- /dev/null +++ b/drivers/char/lrng/lrng_selftest.c @@ -0,0 +1,344 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause +/* + * LRNG power-on and on-demand self-test + * + * Copyright (C) 2016 - 2020, Stephan Mueller <smueller@xxxxxxxxxx> + */ + +/* + * In addition to the self-tests below, the following LRNG components + * are covered with self-tests during regular operation: + * + * * power-on self-test: SP800-90A DRBG provided by the Linux kernel crypto API + * * power-on self-test: PRNG provided by the Linux kernel crypto API + * * runtime test: Raw noise source data testing including SP800-90B compliant + * tests when enabling CONFIG_LRNG_HEALTH_TESTS + * + * Additional developer tests present with LRNG code: + * * SP800-90B APT and RCT test enforcement validation when enabling + * CONFIG_LRNG_APT_BROKEN or CONFIG_LRNG_RCT_BROKEN. + * * Collection of raw entropy from the interrupt noise source when enabling + * CONFIG_LRNG_TESTING and pulling the data from the kernel with the provided + * interface. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/lrng.h> +#include <linux/slab.h> + +#include "lrng_chacha20.h" +#include "lrng_internal.h" +#include "lrng_sw_noise.h" + +#define LRNG_SELFTEST_PASSED 0 +#define LRNG_SEFLTEST_ERROR_TIME (1 << 0) +#define LRNG_SEFLTEST_ERROR_CHACHA20 (1 << 1) +#define LRNG_SEFLTEST_ERROR_HASH (1 << 2) +#define LRNG_SELFTEST_NOT_EXECUTED 0xffffffff + +static u32 lrng_data_selftest_ptr = 0; +static u32 lrng_data_selftest[LRNG_DATA_ARRAY_SIZE]; + +static unsigned int lrng_selftest_status = LRNG_SELFTEST_NOT_EXECUTED; + +static inline void lrng_selftest_bswap32(u32 *ptr, u32 words) +{ + u32 i; + + /* Byte-swap data which is an LE representation */ + for (i = 0; i < words; i++) { + __le32 *p = (__le32 *)ptr; + + *p = cpu_to_le32(*ptr); + ptr++; + } +} + +static inline void lrng_data_process_selftest_insert(u32 time) +{ + u32 ptr = lrng_data_selftest_ptr++ & LRNG_DATA_WORD_MASK; + + lrng_data_selftest[lrng_data_idx2array(ptr)] |= + lrng_data_slot_val(time & LRNG_DATA_SLOTSIZE_MASK, + lrng_data_idx2slot(ptr)); +} + +static inline void lrng_data_process_selftest_u32(uint32_t data) +{ + uint32_t pre_ptr, ptr, mask; + + /* Increment pointer by number of slots taken for input value */ + lrng_data_selftest_ptr += LRNG_DATA_SLOTS_PER_UINT; + + /* ptr to current unit */ + ptr = lrng_data_selftest_ptr; + /* ptr to previous unit */ + pre_ptr = (lrng_data_selftest_ptr - LRNG_DATA_SLOTS_PER_UINT) & + LRNG_DATA_WORD_MASK; + ptr &= LRNG_DATA_WORD_MASK; + + /* mask to split data into the two parts for the two units */ + mask = ((1 << (pre_ptr & (LRNG_DATA_SLOTS_PER_UINT - 1)) * + LRNG_DATA_SLOTSIZE_BITS)) - 1; + + /* MSB of data go into previous unit */ + lrng_data_selftest[lrng_data_idx2array(pre_ptr)] |= data & ~mask; + + /* LSB of data go into current unit */ + lrng_data_selftest[lrng_data_idx2array(ptr)] = data & mask; +} + +static unsigned int lrng_data_process_selftest(void) +{ + u32 time; + u32 idx_zero_compare = (0 << 0) | (1 << 8) | (2 << 16) | (3 << 24); + u32 idx_one_compare = (4 << 0) | (5 << 8) | (6 << 16) | (7 << 24); + u32 idx_last_compare = + (((LRNG_DATA_NUM_VALUES - 4) & LRNG_DATA_SLOTSIZE_MASK) << 0) | + (((LRNG_DATA_NUM_VALUES - 3) & LRNG_DATA_SLOTSIZE_MASK) << 8) | + (((LRNG_DATA_NUM_VALUES - 2) & LRNG_DATA_SLOTSIZE_MASK) << 16) | + (((LRNG_DATA_NUM_VALUES - 1) & LRNG_DATA_SLOTSIZE_MASK) << 24); + + (void)idx_one_compare; + + lrng_data_process_selftest_insert(0); + /* + * Note, when using lrng_data_process_u32() on unaligned ptr, + * the first slots will go into next word, and the last slots go + * into the previous word. + */ + lrng_data_process_selftest_u32((4 << 0) | (1 << 8) | (2 << 16) | + (3 << 24)); + lrng_data_process_selftest_insert(5); + lrng_data_process_selftest_insert(6); + lrng_data_process_selftest_insert(7); + + if ((lrng_data_selftest[0] != idx_zero_compare) || + (lrng_data_selftest[1] != idx_one_compare)) + goto err; + + /* Reset for next test */ + lrng_data_selftest[0] = 0; + lrng_data_selftest[1] = 0; + lrng_data_selftest_ptr = 0; + + for (time = 0; time < LRNG_DATA_NUM_VALUES; time++) + lrng_data_process_selftest_insert(time); + + if ((lrng_data_selftest[0] != idx_zero_compare) || + (lrng_data_selftest[1] != idx_one_compare) || + (lrng_data_selftest[LRNG_DATA_ARRAY_SIZE - 1] != idx_last_compare)) + goto err; + + return LRNG_SELFTEST_PASSED; + +err: + pr_err("LRNG data array self-test FAILED\n"); + return LRNG_SEFLTEST_ERROR_TIME; +} + +/* The test vectors are taken from crypto/testmgr.h */ +static unsigned int lrng_hash_selftest(void) +{ + SHASH_DESC_ON_STACK(shash, NULL); + const struct lrng_crypto_cb *crypto_cb = &lrng_cc20_crypto_cb; + static const u8 lrng_hash_selftest_result[] = +#ifdef CONFIG_CRYPTO_LIB_SHA256 + { 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea, + 0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23, + 0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c, + 0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad }; +#else /* CONFIG_CRYPTO_LIB_SHA256 */ + { 0xa9, 0x99, 0x3e, 0x36, 0x47, 0x06, 0x81, 0x6a, 0xba, 0x3e, + 0x25, 0x71, 0x78, 0x50, 0xc2, 0x6c, 0x9c, 0xd0, 0xd8, 0x9d }; +#endif /* CONFIG_CRYPTO_LIB_SHA256 */ + static const u8 hash_input[] = { 0x61, 0x62, 0x63 }; /* "abc" */ + u8 digest[sizeof(lrng_hash_selftest_result)] __aligned(sizeof(u32)); + + BUG_ON(sizeof(digest) != crypto_cb->lrng_hash_digestsize(NULL)); + + if (!crypto_cb->lrng_hash_init(shash, NULL) && + !crypto_cb->lrng_hash_update(shash, hash_input, + sizeof(hash_input)) && + !crypto_cb->lrng_hash_final(shash, digest) && + !memcmp(digest, lrng_hash_selftest_result, sizeof(digest))) + return 0; + + pr_err("LRNG %s Hash self-test FAILED\n", crypto_cb->lrng_hash_name()); + return LRNG_SEFLTEST_ERROR_HASH; +} + +/* + * The test vectors were generated using the ChaCha20 DRNG from + * https://www.chronox.de/chacha20.html + */ +static unsigned int lrng_chacha20_drng_selftest(void) +{ + const struct lrng_crypto_cb *crypto_cb = &lrng_cc20_crypto_cb; + u8 seed[CHACHA_KEY_SIZE * 2] = { + 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, + 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, + 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, + 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, + 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, + 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, + 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, + 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, + }; + struct chacha20_block chacha20; + int ret; + u8 outbuf[CHACHA_KEY_SIZE * 2] __aligned(sizeof(u32)); + + /* + * Expected result when ChaCha20 DRNG state is zero: + * * constants are set to "expand 32-byte k" + * * remaining state is 0 + * and pulling one half ChaCha20 DRNG block. + */ + static const u8 expected_halfblock[CHACHA_KEY_SIZE] = { + 0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90, + 0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28, + 0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a, + 0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7 }; + + /* + * Expected result when ChaCha20 DRNG state is zero: + * * constants are set to "expand 32-byte k" + * * remaining state is 0 + * followed by a reseed with two keyblocks + * 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, + * 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, + * 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, + * 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, + * 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, + * 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, + * 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, + * 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f + * and pulling one ChaCha20 DRNG block. + */ + static const u8 expected_oneblock[CHACHA_KEY_SIZE * 2] = { + 0xf5, 0xb4, 0xb6, 0x5a, 0xec, 0xcd, 0x5a, 0x65, + 0x87, 0x56, 0xe3, 0x86, 0x51, 0x54, 0xfc, 0x90, + 0x56, 0xff, 0x5e, 0xae, 0x58, 0xf2, 0x01, 0x88, + 0xb1, 0x7e, 0xb8, 0x2e, 0x17, 0x9a, 0x27, 0xe6, + 0x86, 0xb3, 0xed, 0x33, 0xf7, 0xb9, 0x06, 0x05, + 0x8a, 0x2d, 0x1a, 0x93, 0xc9, 0x0b, 0x80, 0x04, + 0x03, 0xaa, 0x60, 0xaf, 0xd5, 0x36, 0x40, 0x11, + 0x67, 0x89, 0xb1, 0x66, 0xd5, 0x88, 0x62, 0x6d }; + + /* + * Expected result when ChaCha20 DRNG state is zero: + * * constants are set to "expand 32-byte k" + * * remaining state is 0 + * followed by a reseed with one key block plus one byte + * 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, + * 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, + * 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, + * 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, + * 0x20 + * and pulling less than one ChaCha20 DRNG block. + */ + static const u8 expected_block_nonalinged[CHACHA_KEY_SIZE + 4] = { + 0x9d, 0xdd, 0x4f, 0xbe, 0x97, 0xcd, 0x8e, 0x15, + 0xb3, 0xc4, 0x1a, 0x17, 0x49, 0x29, 0x32, 0x7c, + 0xb3, 0x84, 0xa4, 0x9b, 0xa7, 0x14, 0xb3, 0xc1, + 0x5b, 0x3b, 0xfb, 0xa1, 0xe4, 0x23, 0x42, 0x8e, + 0x08, 0x1f, 0x53, 0xa2 }; + + BUILD_BUG_ON(sizeof(seed) % sizeof(u32)); + + memset(&chacha20, 0, sizeof(chacha20)); + lrng_cc20_init_rfc7539(&chacha20); + lrng_selftest_bswap32((u32 *)seed, sizeof(seed) / sizeof(u32)); + + /* Generate with zero state */ + ret = crypto_cb->lrng_drng_generate_helper(&chacha20, outbuf, + sizeof(expected_halfblock)); + if (ret != sizeof(expected_halfblock)) + goto err; + if (memcmp(outbuf, expected_halfblock, sizeof(expected_halfblock))) + goto err; + + /* Clear state of DRNG */ + memset(&chacha20.key.u[0], 0, 48); + + /* Reseed with 2 key blocks */ + ret = crypto_cb->lrng_drng_seed_helper(&chacha20, seed, + sizeof(expected_oneblock)); + if (ret < 0) + goto err; + ret = crypto_cb->lrng_drng_generate_helper(&chacha20, outbuf, + sizeof(expected_oneblock)); + if (ret != sizeof(expected_oneblock)) + goto err; + if (memcmp(outbuf, expected_oneblock, sizeof(expected_oneblock))) + goto err; + + /* Clear state of DRNG */ + memset(&chacha20.key.u[0], 0, 48); + + /* Reseed with 1 key block and one byte */ + ret = crypto_cb->lrng_drng_seed_helper(&chacha20, seed, + sizeof(expected_block_nonalinged)); + if (ret < 0) + goto err; + ret = crypto_cb->lrng_drng_generate_helper(&chacha20, outbuf, + sizeof(expected_block_nonalinged)); + if (ret != sizeof(expected_block_nonalinged)) + goto err; + if (memcmp(outbuf, expected_block_nonalinged, + sizeof(expected_block_nonalinged))) + goto err; + + return LRNG_SELFTEST_PASSED; + +err: + pr_err("LRNG ChaCha20 DRNG self-test FAILED\n"); + return LRNG_SEFLTEST_ERROR_CHACHA20; +} + +static int lrng_selftest(void) +{ + unsigned int ret = lrng_data_process_selftest(); + + ret |= lrng_chacha20_drng_selftest(); + ret |= lrng_hash_selftest(); + + if (ret) { + if (IS_ENABLED(CONFIG_LRNG_SELFTEST_PANIC)) + panic("LRNG self-tests failed: %u\n", ret); + } else { + pr_info("LRNG self-tests passed\n"); + } + + lrng_selftest_status = ret; + + if (lrng_selftest_status) + return -EFAULT; + return 0; +} + +#ifdef CONFIG_SYSFS +/* Re-perform self-test when any value is written to the sysfs file. */ +static int lrng_selftest_sysfs_set(const char *val, + const struct kernel_param *kp) +{ + return lrng_selftest(); +} + +static const struct kernel_param_ops lrng_selftest_sysfs = { + .set = lrng_selftest_sysfs_set, + .get = param_get_uint, +}; +module_param_cb(selftest_status, &lrng_selftest_sysfs, &lrng_selftest_status, + 0644); +#endif /* CONFIG_SYSFS */ + +static int __init lrng_selftest_init(void) +{ + return lrng_selftest(); +} + +module_init(lrng_selftest_init); -- 2.26.2
