kernel/include/crypto/drbg.h, branch linux-5.11.y

crypto: drbg - always seeded with SP800-90B compliant noise source

2020-04-24T07:42:17Z

As the Jitter RNG provides an SP800-90B compliant noise source, use this noise source always for the (re)seeding of the DRBG. To make sure the DRBG is always properly seeded, the reseed threshold is reduced to 1<<20 generate operations. The Jitter RNG may report health test failures. Such health test failures are treated as transient as follows. The DRBG will not reseed from the Jitter RNG (but from get_random_bytes) in case of a health test failure. Though, it produces the requested random number. The Jitter RNG has a failure counter where at most 1024 consecutive resets due to a health test failure are considered as a transient error. If more consecutive resets are required, the Jitter RNG will return a permanent error which is returned to the caller by the DRBG. With this approach, the worst case reseed threshold is significantly lower than mandated by SP800-90A in order to seed with an SP800-90B noise source: the DRBG has a reseed threshold of 2^20 * 1024 = 2^30 generate requests. Yet, in case of a transient Jitter RNG health test failure, the DRBG is seeded with the data obtained from get_random_bytes. However, if the Jitter RNG fails during the initial seeding operation even due to a health test error, the DRBG will send an error to the caller because at that time, the DRBG has received no seed that is SP800-90B compliant. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu

crypto: drbg - add FIPS 140-2 CTRNG for noise source

2019-05-23T06:01:06Z

FIPS 140-2 section 4.9.2 requires a continuous self test of the noise source. Up to kernel 4.8 drivers/char/random.c provided this continuous self test. Afterwards it was moved to a location that is inconsistent with the FIPS 140-2 requirements. The relevant patch was e192be9d9a30555aae2ca1dc3aad37cba484cd4a . Thus, the FIPS 140-2 CTRNG is added to the DRBG when it obtains the seed. This patch resurrects the function drbg_fips_continous_test that existed some time ago and applies it to the noise sources. The patch that removed the drbg_fips_continous_test was b3614763059b82c26bdd02ffcb1c016c1132aad0 . The Jitter RNG implements its own FIPS 140-2 self test and thus does not need to be subjected to the test in the DRBG. The patch contains a tiny fix to ensure proper zeroization in case of an error during the Jitter RNG data gathering. Signed-off-by: Stephan Mueller Reviewed-by: Yann Droneaud Signed-off-by: Herbert Xu

crypto: drbg - in-place cipher operation for CTR

2018-08-03T10:05:48Z

crypto: drbg - eliminate constant reinitialization of SGL

2018-07-20T05:51:21Z

The CTR DRBG requires two SGLs pointing to input/output buffers for the CTR AES operation. The used SGLs always have only one entry. Thus, the SGL can be initialized during allocation time, preventing a re-initialization of the SGLs during each call. The performance is increased by about 1 to 3 percent depending on the size of the requested buffer size. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu

crypto: drbg - move to generic async completion

2017-11-03T14:11:19Z

DRBG is starting an async. crypto op and waiting for it complete. Move it over to generic code doing the same. The code now also passes CRYPTO_TFM_REQ_MAY_SLEEP flag indicating crypto request memory allocation may use GFP_KERNEL which should be perfectly fine as the code is obviously sleeping for the completion of the request any way. Signed-off-by: Gilad Ben-Yossef Signed-off-by: Herbert Xu

crypto: drbg - prevent invalid SG mappings

2016-11-30T11:46:44Z

When using SGs, only heap memory (memory that is valid as per virt_addr_valid) is allowed to be referenced. The CTR DRBG used to reference the caller-provided memory directly in an SG. In case the caller provided stack memory pointers, the SG mapping is not considered to be valid. In some cases, this would even cause a paging fault. The change adds a new scratch buffer that is used unconditionally to catch the cases where the caller-provided buffer is not suitable for use in an SG. The crypto operation of the CTR DRBG produces its output with that scratch buffer and finally copies the content of the scratch buffer to the caller's buffer. The scratch buffer is allocated during allocation time of the CTR DRBG as its access is protected with the DRBG mutex. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu

crypto: drbg - use aligned buffers

2016-06-15T09:07:53Z

Hardware cipher implementation may require aligned buffers. All buffers that potentially are processed with a cipher are now aligned. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu

crypto: drbg - use CTR AES instead of ECB AES

2016-06-15T09:07:53Z

The CTR DRBG derives its random data from the CTR that is encrypted with AES. This patch now changes the CTR DRBG implementation such that the CTR AES mode is employed. This allows the use of steamlined CTR AES implementation such as ctr-aes-aesni. Unfortunately there are the following subtile changes we need to apply when using the CTR AES mode: - the CTR mode increments the counter after the cipher operation, but the CTR DRBG requires the increment before the cipher op. Hence, the crypto_inc is applied to the counter (drbg->V) once it is recalculated. - the CTR mode wants to encrypt data, but the CTR DRBG is interested in the encrypted counter only. The full CTR mode is the XOR of the encrypted counter with the plaintext data. To access the encrypted counter, the patch uses a NULL data vector as plaintext to be "encrypted". Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu

crypto: drbg - remove FIPS 140-2 continuous test

2016-01-25T14:42:11Z

The newly released FIPS 140-2 IG 9.8 specifies that for SP800-90A compliant DRBGs, the FIPS 140-2 continuous random number generator test is not required any more. This patch removes the test and all associated data structures. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu

crypto: drbg - reseed often if seedsource is degraded

2015-06-10T11:14:05Z

As required by SP800-90A, the DRBG implements are reseeding threshold. This threshold is at 2**48 (64 bit) and 2**32 bit (32 bit) as implemented in drbg_max_requests. With the recently introduced changes, the DRBG is now always used as a stdrng which is initialized very early in the boot cycle. To ensure that sufficient entropy is present, the Jitter RNG is added to even provide entropy at early boot time. However, the 2nd seed source, the nonblocking pool, is usually degraded at that time. Therefore, the DRBG is seeded with the Jitter RNG (which I believe contains good entropy, which however is questioned by others) and is seeded with a degradded nonblocking pool. This seed is now used for quasi the lifetime of the system (2**48 requests is a lot). The patch now changes the reseed threshold as follows: up until the time the DRBG obtains a seed from a fully iniitialized nonblocking pool, the reseeding threshold is lowered such that the DRBG is forced to reseed itself resonably often. Once it obtains the seed from a fully initialized nonblocking pool, the reseed threshold is set to the value required by SP800-90A. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu