[PATCH v5 0/3] Remove secret-size restrictions for hashes

[Mark O'Donovan <shiftee@posteo.net>]

This relates to the hash functions used to transform the secret.
The kernel currently restricts us to using secrets equal in size
to the transformation hash function they use.
e.g. 32 byte secrets with the SHA-256(32 byte) hash function.

This restriction is not required by the spec and means
incompatibility with more permissive implementations.

With these patches the example secret from the spec should now
be permitted with any of the following:
DHHC-1:00:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:
DHHC-1:01:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:
DHHC-1:02:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:
DHHC-1:03:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:

Note: Secrets are still restricted to 32,48 or 64 bits.

v1:
- Initial submission

v2:
- Added transformed_len as member of struct nvme_dhchap_key

v3:
- Return a struct nvme_dhchap_key from nvme_auth_transform_key()

v4:
- added helper to caclulate key struct size using struct_size()
- Break up lines which were too long
- Replace ternary operator with if
- Add missing ERR_CAST()

v5:
- Removed newly redundant check found by kernel test robot

Mark O'Donovan (3):
  nvme-auth: alloc nvme_dhchap_key as single buffer
  nvme-auth: use transformed key size to create resp
  nvme-auth: allow mixing of secret and hash lengths

 drivers/nvme/common/auth.c | 68 ++++++++++++++++++++++----------------
 drivers/nvme/host/auth.c   | 30 ++++++++---------
 drivers/nvme/target/auth.c | 31 +++++++++--------
 include/linux/nvme-auth.h  |  7 ++--
 4 files changed, 76 insertions(+), 60 deletions(-)

-- 
2.39.2