[PATCH v4 00/14] security: digest_cache LSM

[Paul Moore]

On Mon, Apr 15, 2024 at 10:25 AM Roberto Sassu
<roberto.sassu at huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu at huawei.com>
>
> Integrity detection and protection has long been a desirable feature, to
> reach a large user base and mitigate the risk of flaws in the software
> and attacks.
>
> However, while solutions exist, they struggle to reach the large user
> base, due to requiring higher than desired constraints on performance,
> flexibility and configurability, that only security conscious people are
> willing to accept.
>
> This is where the new digest_cache LSM comes into play, it offers
> additional support for new and existing integrity solutions, to make
> them faster and easier to deploy.
>
> The full documentation with the motivation and the solution details can be
> found in patch 14.
>
> The IMA integration patch set will be introduced separately. Also a PoC
> based on the current version of IPE can be provided.

I'm not sure we want to implement a cache as a LSM.  I'm sure it would
work, but historically LSMs have provided some form of access control,
measurement, or other traditional security service.  A digest cache,
while potentially useful for a variety of security related
applications, is not a security service by itself, it is simply a file
digest storage mechanism.

I think it's fine if an individual LSM wants to implement a file
digest cache as part of its own functionality, but a generalized file
digest cache seems like something that should be part of the general
kernel, and not implemented as a LSM.

-- 
paul-moore.com