Re: [PATCH 00/18] Migrate rpcsec_gss_krb5 to the crypto/krb5 library

[Jeff Layton <jlayton@kernel.org>]

On Mon, 2026-04-27 at 09:50 -0400, Chuck Lever wrote:
> The rpcsec_gss_krb5 module carries its own Kerberos 5 crypto imple-
> mentation: key derivation, CBC-CTS encryption, HMAC checksumming,
> and the encrypt-then-MAC construction from RFC 8009. Keeping
> cryptographic code inside an RPC module means it receives review
> only from the SUNRPC maintainers, who lack deep crypto expertise.
> Vulnerabilities and algorithmic errors can persist unnoticed.
> 
> Replacing the private SunRPC Kerberos implementation eliminates
> this duplicated audit surface. A single implementation of Kerberos
> 5 key derivation and authenticated encryption is easier to verify
> than two independent copies. New encryption types and hardware
> offload added to crypto/krb5 will automatically become available
> to SunRPC Kerberos consumers.
> 
> The crypto/krb5 library handles enctype differences internally, so
> a single encrypt function and a single decrypt function serve all
> enctypes, eliminating the per-enctype dispatch table that previously
> existed in struct gss_krb5_enctype.
> 
> RFC 4121 Section 4.2.4 requires MIC checksums to cover the message
> body followed by the GSS token header. The crypto/krb5 get_mic/
> verify_mic API hashes optional metadata before the scatterlist
> data, which is the wrong order for the GSS header. The header is
> therefore placed at the end of the scatterlist rather than passed
> as the metadata parameter, and a dedicated gss_krb5_mic_build_sg()
> helper constructs this three-section layout (checksum area, message
> body, token header) with proper sg_mark_end() termination.
> 
> This implementation was available during the Spring 2026 NFS bake-
> a-thon, and received testing there.
> 
> ---
> Chuck Lever (18):
>       SUNRPC: Add Kconfig dependency on CRYPTO_KRB5
>       SUNRPC: Add crypto/krb5 enctype lookup to krb5_ctx
>       SUNRPC: Add helpers to convert xdr_buf byte ranges to scatterlists
>       SUNRPC: Add errno-to-GSS status conversion helper
>       SUNRPC: Prepare crypto/krb5 encryption and checksum handles
>       SUNRPC: Switch wrap token encryption to crypto/krb5
>       SUNRPC: Switch wrap token decryption to crypto/krb5
>       SUNRPC: Switch Camellia decrypt to crypto/krb5
>       SUNRPC: Switch MIC token generation to crypto/krb5
>       SUNRPC: Switch MIC token verification to crypto/krb5
>       SUNRPC: Remove get_mic/verify_mic function pointers from enctype table
>       SUNRPC: Remove wrap/unwrap function pointers from enctype table
>       SUNRPC: Remove encrypt/decrypt function pointers from enctype table
>       SUNRPC: Remove legacy skcipher/ahash handles from krb5_ctx
>       SUNRPC: Remove dead code from rpcsec_gss_krb5
>       SUNRPC: Remove per-enctype Kconfig options
>       SUNRPC: Remove redundant crypto Kconfig dependencies
>       SUNRPC: Remove dead rpcsec_gss_krb5 definitions
> 
>  include/linux/sunrpc/gss_krb5.h         |  105 --
>  include/linux/sunrpc/xdr.h              |   16 +-
>  net/sunrpc/.kunitconfig                 |   29 -
>  net/sunrpc/Kconfig                      |   56 +-
>  net/sunrpc/auth_gss/Makefile            |    4 +-
>  net/sunrpc/auth_gss/gss_krb5_crypto.c   | 1014 ++++-------------
>  net/sunrpc/auth_gss/gss_krb5_internal.h |  155 +--
>  net/sunrpc/auth_gss/gss_krb5_keys.c     |  546 ---------
>  net/sunrpc/auth_gss/gss_krb5_mech.c     |  441 ++------
>  net/sunrpc/auth_gss/gss_krb5_seal.c     |   47 +-
>  net/sunrpc/auth_gss/gss_krb5_test.c     | 1868 -------------------------------
>  net/sunrpc/auth_gss/gss_krb5_unseal.c   |   36 +-
>  net/sunrpc/auth_gss/gss_krb5_wrap.c     |   13 +-
>  net/sunrpc/xdr.c                        |  266 +++--
>  14 files changed, 573 insertions(+), 4023 deletions(-)
> ---
> base-commit: f3a96328282e8d41ba9f478d24ac122e4cbd2989
> change-id: 20260316-crypto-krb5-api-b9ee22636698
> 
> Best regards,
> --  
> Chuck Lever

Love that diffstat. Nice work! 

One comment in general: Do you need to add Assisted-by: tags to any of
this? You can add this to the set:

Reviewed-by: Jeff Layton <jlayton@kernel.org>