[PATCH v2 0/2] nvme: fixup HKDF-Expand-Label implementation

[Chris Leech]

As per RFC 8446 (TLS 1.3) the HKDF-Expand-Label function is using vectors
for the 'label' and 'context' field, but defines these vectors as a string
prefixed with the string length (in binary). The implementation in nvme
is missing the length prefix which was causing interoperability issues
with spec-conformant implementations.

This patchset adds a function 'hkdf_expand_label()' to correctly implement
the HKDF-Expand-Label functionality and modifies the nvme driver to utilize
this function instead of the open-coded implementation.

As usual, comments and reviews are welcome.

Changes from v1:
 - Moved hkdf_expand_label() from crypto/hkdf.c to nvme/common/auth.c.
   It's not really an RFC 5869 HKDF function, it's defined for TLS but
   currently only used by nvme in-kernel.
 - Fixed kdoc label_len -> labellen
 - Replaced "static const char []" with "const char *", it's just
   clearer and generates the same code with a string literal assignment.

(I've left the crypto emails on this version, mostly to make it known
that hkdf_expand_label() has been moved as Eric asked.)

Chris Leech (2):
  nvme-auth: add hkdf_expand_label()
  nvme-auth: use hkdf_expand_label()

 drivers/nvme/common/auth.c | 86 +++++++++++++++++++++++++++++---------
 1 file changed, 66 insertions(+), 20 deletions(-)

-- 
2.50.1