[PATCH v3 1/7] security: rename security_kernel_read_file() hook

James Morris [off-list ref] writes:

On Fri, 25 May 2018, Eric W. Biederman wrote:

quoted

James Morris [off-list ref] writes:

quoted

On Thu, 24 May 2018, Eric W. Biederman wrote:

quoted

Below is where I suggest you start on sorting out these security hooks.
- Adding a security_kernel_arg to catch when you want to allow/deny the
  use of an argument to a syscall.  What security_kernel_file_read and
  security_kernel_file_post_read have been abused for.

NAK. This abstraction is too semantically weak.

LSM hooks need to map to stronger semantics so we can reason about what 
the hook and the policy is supposed to be mediating.

I will take that as an extremely weak nack as all I did was expose the
existing code and what the code is currently doing.  I don't see how you
can NAK what is already being merged and used.

It's a strong NAK.

We are either not understading each other or you have just strong NAK'd
part of the existing LSM api.  Not my proposal.

LSM is a logical API, it provides an abstraction layer for security 
policies to mediate kernel security behaviors.

The way it deals with firmware blobs and module loading is not logical.
It is some random pass a NULL pointer into some other security hook.

Adding an argument to a syscall is not a security behavior.

Loading a firmware file is.

It is a firmware blob not a file.  Perhaps the blob is stored as a file
on-disk, perhaps it is not.

The similar case with kexec never stores all of the data in a file.

Why module_init (which does not take a file) is calling a file based lsm
hook is also bizarre.


Perhaps that means all 3 of these cases should have their own void
security hooks.  Perhaps it means something else.  I just know the name
on the security hook, how it is getting called, and how it is getting
used simply do not agree.

Eric
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