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2021-12-31crypto: jitter - add oversampling of noise sourceStephan Müller1-2/+21
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). Note, this patch causes the Jitter RNG to cut its performance in half in FIPS mode because the conditioning function of the LFSR produces 64 bits of entropy in one block. The oversampling requires that additionally 64 bits of entropy are sampled from the noise source. If the conditioner is changed, such as using SHA-256, the impact of the oversampling is only one fourth, because for the 256 bit block of the conditioner, only 64 additional bits from the noise source must be sampled. This patch is derived from the user space jitterentropy-library. Signed-off-by: Stephan Mueller <smueller@chronox.de> Reviewed-by: Simo Sorce <simo@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2021-12-11crypto: jitter - quit sample collection loop upon RCT failureNicolai Stange1-1/+1
The jitterentropy collection loop in jent_gen_entropy() can in principle run indefinitely without making any progress if it only receives stuck measurements as determined by jent_stuck(). After 31 consecutive stuck samples, the Repetition Count Test (RCT) would fail anyway and the jitterentropy RNG instances moved into ->health_failure == 1 state. jent_gen_entropy()'s caller, jent_read_entropy() would then check for this ->health_failure condition and return an error if found set. It follows that there's absolutely no point in continuing the collection loop in jent_gen_entropy() once the RCT has failed. Make the jitterentropy collection loop more robust by terminating it upon jent_health_failure() so that it won't continue to run indefinitely without making any progress. Signed-off-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2021-12-11crypto: jitter - don't limit ->health_failure check to FIPS modeNicolai Stange1-4/+0
The jitterentropy's Repetition Count Test (RCT) as well as the Adaptive Proportion Test (APT) are run unconditionally on any collected samples. However, their result, i.e. ->health_failure, will only get checked if fips_enabled is set, c.f. the jent_health_failure() wrapper. I would argue that a RCT or APT failure indicates that something's seriously off and that this should always be reported as an error, independently of whether FIPS mode is enabled or not: it should be up to callers whether or not and how to handle jitterentropy failures. Make jent_health_failure() to unconditionally return ->health_failure, independent of whether fips_enabled is set. Note that fips_enabled isn't accessed from the jitterentropy code anymore now. Remove the linux/fips.h include as well as the jent_fips_enabled() wrapper. Signed-off-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2021-11-26crypto: jitter - consider 32 LSB for APTStephan Müller1-2/+1
The APT compares the current time stamp with a pre-set value. The current code only considered the 4 LSB only. Yet, after reviews by mathematicians of the user space Jitter RNG version >= 3.1.0, it was concluded that the APT can be calculated on the 32 LSB of the time delta. Thi change is applied to the kernel. This fixes a bug where an AMD EPYC fails this test as its RDTSC value contains zeros in the LSB. The most appropriate fix would have been to apply a GCD calculation and divide the time stamp by the GCD. Yet, this is a significant code change that will be considered for a future update. Note, tests showed that constantly the GCD always was 32 on these systems, i.e. the 5 LSB were always zero (thus failing the APT since it only considered the 4 LSB for its calculation). Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2021-09-17crypto: jitter - drop kernel-doc notationRandy Dunlap1-12/+12
Drop "begin kernel-doc (/**)" entries in jitterentropy.c since they are not in kernel-doc format and they cause many complaints (warnings) from scripts/kernel-doc. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Stephan Mueller <smueller@chronox.de> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: linux-crypto@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2021-03-26crypto: jitterentropy - Put constants on the right side of the expressionMilan Djurovic1-4/+4
This patch fixes the following checkpatch.pl warnings: crypto/jitterentropy.c:600: WARNING: Comparisons should place the constant on the right side of the test crypto/jitterentropy.c:681: WARNING: Comparisons should place the constant on the right side of the test crypto/jitterentropy.c:772: WARNING: Comparisons should place the constant on the right side of the test crypto/jitterentropy.c:829: WARNING: Comparisons should place the constant on the right side of the test Signed-off-by: Milan Djurovic <mdjurovic@zohomail.com> Reviewed-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-07-23crypto: Replace HTTP links with HTTPS onesAlexander A. Klimov1-2/+2
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-04-24crypto: jitter - SP800-90B complianceStephan Müller1-101/+316
SP800-90B specifies various requirements for the noise source(s) that may seed any DRNG including SP800-90A DRBGs. In November 2020, SP800-90B will be mandated for all noise sources that provide entropy to DRBGs as part of a FIPS 140-[2|3] validation or other evaluation types. Without SP800-90B compliance, a noise source is defined to always deliver zero bits of entropy. This patch ports the SP800-90B compliance from the user space Jitter RNG version 2.2.0. The following changes are applied: - addition of (an enhanced version of) the repetitive count test (RCT) from SP800-90B section 4.4.1 - the enhancement is due to the fact of using the stuck test as input to the RCT. - addition of the adaptive proportion test (APT) from SP800-90B section 4.4.2 - update of the power-on self test to perform a test measurement of 1024 noise samples compliant to SP800-90B section 4.3 - remove of the continuous random number generator test which is replaced by APT and RCT Health test failures due to the SP800-90B operation are only enforced in FIPS mode. If a runtime health test failure is detected, the Jitter RNG is reset. If more than 1024 resets in a row are performed, a permanent error is returned to the caller. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-10-18crypto: jitter - add header to fix buildwarningsBen Dooks1-6/+1
Fix the following build warnings by adding a header for the definitions shared between jitterentropy.c and jitterentropy-kcapi.c. Fixes the following: crypto/jitterentropy.c:445:5: warning: symbol 'jent_read_entropy' was not declared. Should it be static? crypto/jitterentropy.c:475:18: warning: symbol 'jent_entropy_collector_alloc' was not declared. Should it be static? crypto/jitterentropy.c:509:6: warning: symbol 'jent_entropy_collector_free' was not declared. Should it be static? crypto/jitterentropy.c:516:5: warning: symbol 'jent_entropy_init' was not declared. Should it be static? crypto/jitterentropy-kcapi.c:59:6: warning: symbol 'jent_zalloc' was not declared. Should it be static? crypto/jitterentropy-kcapi.c:64:6: warning: symbol 'jent_zfree' was not declared. Should it be static? crypto/jitterentropy-kcapi.c:69:5: warning: symbol 'jent_fips_enabled' was not declared. Should it be static? crypto/jitterentropy-kcapi.c:74:6: warning: symbol 'jent_panic' was not declared. Should it be static? crypto/jitterentropy-kcapi.c:79:6: warning: symbol 'jent_memcpy' was not declared. Should it be static? crypto/jitterentropy-kcapi.c:93:6: warning: symbol 'jent_get_nstime' was not declared. Should it be static? Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Reviewed-by: Stephan Mueller <smueller@chronox.de Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-10-04crypto: jitter - fix commentsAlexander E. Patrakov1-3/+3
One should not say "ec can be NULL" and then dereference it. One cannot talk about the return value if the function returns void. Signed-off-by: Alexander E. Patrakov <patrakov@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-06-06crypto: jitter - update implementation to 2.1.2Stephan Müller1-223/+82
The Jitter RNG implementation is updated to comply with upstream version 2.1.2. The change covers the following aspects: * Time variation measurement is conducted over the LFSR operation instead of the XOR folding * Invcation of stuck test during initialization * Removal of the stirring functionality and the Von-Neumann unbiaser as the LFSR using a primitive and irreducible polynomial generates an identical distribution of random bits This implementation was successfully used in FIPS 140-2 validations as well as in German BSI evaluations. This kernel implementation was tested as follows: * The unchanged kernel code file jitterentropy.c is compiled as part of user space application to generate raw unconditioned noise data. That data is processed with the NIST SP800-90B non-IID test tool to verify that the kernel code exhibits an equal amount of noise as the upstream Jitter RNG version 2.1.2. * Using AF_ALG with the libkcapi tool of kcapi-rng the Jitter RNG was output tested with dieharder to verify that the output does not exhibit statistical weaknesses. The following command was used: kcapi-rng -n "jitterentropy_rng" -b 100000000000 | dieharder -a -g 200 * The unchanged kernel code file jitterentropy.c is compiled as part of user space application to test the LFSR implementation. The LFSR is injected a monotonically increasing counter as input and the output is fed into dieharder to verify that the LFSR operation does not exhibit statistical weaknesses. * The patch was tested on the Muen separation kernel which returns a more coarse time stamp to verify that the Jitter RNG does not cause regressions with its initialization test considering that the Jitter RNG depends on a high-resolution timer. Tested-by: Reto Buerki <reet@codelabs.ch> Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-06-25crypto: jitterentropy - Delete unnecessary checks before the function call ↵Markus Elfring1-4/+2
"kzfree" The kzfree() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-06-25crypto: jitterentropy - avoid compiler warningsStephan Mueller1-176/+37
The core of the Jitter RNG is intended to be compiled with -O0. To ensure that the Jitter RNG can be compiled on all architectures, separate out the RNG core into a stand-alone C file that can be compiled with -O0 which does not depend on any kernel include file. As no kernel includes can be used in the C file implementing the core RNG, any dependencies on kernel code must be extracted. A second file provides the link to the kernel and the kernel crypto API that can be compiled with the regular compile options of the kernel. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-06-09crypto: drbg - use pragmas for disabling optimizationStephan Mueller1-4/+26
Replace the global -O0 compiler flag from the Makefile with GCC pragmas to mark only the functions required to be compiled without optimizations. This patch also adds a comment describing the rationale for the functions chosen to be compiled without optimizations. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-05-28crypto: jitterentropy - remove timekeeping_valid_for_hresStephan Mueller1-3/+0
The patch removes the use of timekeeping_valid_for_hres which is now marked as internal for the time keeping subsystem. The jitterentropy does not really require this verification as a coarse timer (when random_get_entropy is absent) is discovered by the initialization test of jent_entropy_init, which would cause the jitter rng to not load in that case. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-05-27crypto: jitterentropy - add jitterentropy RNGStephan Mueller1-0/+909
The CPU Jitter RNG provides a source of good entropy by collecting CPU executing time jitter. The entropy in the CPU execution time jitter is magnified by the CPU Jitter Random Number Generator. The CPU Jitter Random Number Generator uses the CPU execution timing jitter to generate a bit stream which complies with different statistical measurements that determine the bit stream is random. The CPU Jitter Random Number Generator delivers entropy which follows information theoretical requirements. Based on these studies and the implementation, the caller can assume that one bit of data extracted from the CPU Jitter Random Number Generator holds one bit of entropy. The CPU Jitter Random Number Generator provides a decentralized source of entropy, i.e. every caller can operate on a private state of the entropy pool. The RNG does not have any dependencies on any other service in the kernel. The RNG only needs a high-resolution time stamp. Further design details, the cryptographic assessment and large array of test results are documented at http://www.chronox.de/jent.html. CC: Andreas Steffen <andreas.steffen@strongswan.org> CC: Theodore Ts'o <tytso@mit.edu> CC: Sandy Harris <sandyinchina@gmail.com> Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>