Re: [PATCH] ksmbd: restore Kerberos logins with released ksmbd-tools

[Namjae Jeon]

On Wed, Oct 21, 2026 at 8:54 PM Michail Andreas Michalopoulos
<mike.michalo@xxxxxxxxx> wrote:
>
> Commit a47634cd729b ("ksmbd: expire SMB sessions when Kerberos tickets
> expire") added a __u64 session_expiry field to struct
> ksmbd_spnego_authen_response, growing it from 156 to 168 bytes.
> ipc_validate_msg() requires the response to have exactly that size, so
> the 156-byte response of every released ksmbd-tools, up to 3.5.7, is
> dropped and Kerberos session setup fails with STATUS_LOGON_FAILURE.
> The other way round, kernels without that commit, including the stable
> trees, drop the 168-byte response of current ksmbd-tools master, and
> ksmbd-tools has no way to tell which layout a kernel expects.
>
> Pass the expiry in the reserved area of the embedded struct
> ksmbd_login_response instead. ksmbd-tools releases with that area
> (3.4.4 and later) allocate the response zeroed and never write to it,
> so they send an expiry of 0, which ksmbd already treats as no expiry.
> The response is 156 bytes again, so it works with those releases, and
> every kernel also accepts a response that sets the expiry. Use two
> __u32 halves, as the reserved area is only 4-byte aligned.
>
> Fixes: a47634cd729b ("ksmbd: expire SMB sessions when Kerberos tickets expire")
> Cc: stable@xxxxxxxxxxxxxxx
> Closes: https://lore.kernel.org/all/CAO+rqLhpPvY0NLrAnZjFXz0gOXnA6zsXxK8xCgtA42XUkSsAeg@xxxxxxxxxxxxxx/
> Assisted-by: LLM
> Signed-off-by: Michail Andreas Michalopoulos <mike.michalo@xxxxxxxxx>
Applied it to #ksmbd-for-next.
Thanks!