Re: [PATCH v2] crypto: testmgr - reinstate kconfig control over full self-tests

[Herbert Xu <herbert@gondor.apana.org.au>]

On Thu, Jun 12, 2025 at 10:47:09AM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Commit 698de822780f ("crypto: testmgr - make it easier to enable the
> full set of tests") removed support for building kernels that run only
> the "fast" set of crypto self-tests by default.  This assumed that
> nearly everyone actually wanted the full set of tests, *if* they had
> already chosen to enable the tests at all.
> 
> Unfortunately, it turns out that both Debian and Fedora intentionally
> have the crypto self-tests enabled in their production kernels.  And for
> production kernels we do need to keep the testing time down, which
> implies just running the "fast" tests, not the full set of tests.
> 
> For Fedora, a reason for enabling the tests in production is that they
> are being (mis)used to meet the FIPS 140-3 pre-operational testing
> requirement.
> 
> However, the other reason for enabling the tests in production, which
> applies to both distros, is that they provide some value in protecting
> users from buggy drivers.  Unfortunately, the crypto/ subsystem has many
> buggy and untested drivers for off-CPU hardware accelerators on rare
> platforms.  These broken drivers get shipped to users, and there have
> been multiple examples of the tests preventing these buggy drivers from
> being used.  So effectively, the tests are being relied on in production
> kernels.  I think this is kind of crazy (untested drivers should just
> not be enabled at all), but that seems to be how things work currently.
> 
> Thus, reintroduce a kconfig option that controls the level of testing.
> Call it CRYPTO_SELFTESTS_FULL instead of the original name
> CRYPTO_MANAGER_EXTRA_TESTS, which was slightly misleading.
> 
> Moreover, given the "production kernel" use case, make CRYPTO_SELFTESTS
> depend on EXPERT instead of DEBUG_KERNEL.
> 
> I also haven't reinstated all the #ifdefs in crypto/testmgr.c.  Instead,
> just rely on the compiler to optimize out unused code.
> 
> Fixes: 40b9969796bf ("crypto: testmgr - replace CRYPTO_MANAGER_DISABLE_TESTS with CRYPTO_SELFTESTS")
> Fixes: 698de822780f ("crypto: testmgr - make it easier to enable the full set of tests")
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> 
> This patch is targeting the crypto tree for 6.16.
> 
> Changed in v2:
>    - Made CRYPTO_SELFTESTS depend on EXPERT
>    - Removed 'default y' from CRYPTO_SELFTESTS_FULL
>    - Improved commit message
> 
>  crypto/Kconfig                 | 25 +++++++++++++++++++++----
>  crypto/testmgr.c               | 15 ++++++++++++---
>  include/crypto/internal/simd.h |  6 ++++--
>  lib/crypto/Makefile            |  2 +-
>  4 files changed, 38 insertions(+), 10 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt