Re: [RFC PATCH v2 1/4] security: ima: call ima_init() again at late_initcall_sync for defered TPM

[Yeoreum Yun <yeoreum.yun@arm.com>]

[...]
> > I understand the need to ensure that the TPM is available, but if it
> > isn't safe to wait to initialize IMA at late_initcall_sync() then it
> > would seem like this is a bad option and we need another mechanism to
> > synchronize IMA with TPM devices.  If it is safe to initalize IMA in
> > late_initcall_sync(), just do that and be done with it.
>
> Within the same initcall level there is no way of ordering the initialization.
> Yeorum attempted to address the ordering issue in commit 0e0546eabcd6
> ("firmware: arm_ffa: Change initcall level of ffa_init() to rootfs_initcall"),
> which is being reverted in this patch set.
>
> Ordering within an initcall level needs to be fixed, but for now retrying at
> late_initcall_sync works for some, hopefully most, cases.

Ordering within an initcall level is not good idea.

Though it came to my mind first long ago,
It also goes against existing mechanisms like deferred probe, and
can cause the driver model’s dependency handling to harden
in the wrong direction. So this I think it wouldn't be an option.

--
Sincerely,
Yeoreum Yun