[PATCH v4 12/17] LSM: Add "contents" flag to kernel_read_file hook

[Mimi Zohar]

On Wed, 2020-07-29 at 10:58 -0700, Kees Cook wrote:
> As with the kernel_load_data LSM hook, add a "contents" flag to the
> kernel_read_file LSM hook that indicates whether the LSM can expect
> a matching call to the kernel_post_read_file LSM hook with the full
> contents of the file. With the coming addition of partial file read
> support for kernel_read_file*() API, the LSM will no longer be able
> to always see the entire contents of a file during the read calls.
> 
> For cases where the LSM must read examine the complete file contents,
> it will need to do so on its own every time the kernel_read_file
> hook is called with contents=false (or reject such cases). Adjust all
> existing LSMs to retain existing behavior.
> 
> Signed-off-by: Kees Cook <keescook at chromium.org>

Reviewed-by: Mimi Zohar <zohar at linux.ibm.com>