Re: [RFC] integrity: wait for completion of i2c initialization using late_initcall_sync()

[Mimi Zohar <zohar@linux.ibm.com>]

On Mon, 2024-07-01 at 22:37 -0400, Mimi Zohar wrote:
> Hi Romain,
> 
> Please limit the subject line to 70 - 75 characters.
> 
> 
> On Mon, 2024-07-01 at 16:58 +0200, Romain Naour wrote:
> > > > [1]
> > > > https://lore.kernel.org/linux-integrity/9b98d912-ba78-402c-a5c8-154bef8794f7@smile.fr/
> > > > [2]
> > > > https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1375425/tda4vm-ima-vs-tpm-builtin-driver-boot-order
> > > > 
> > > > Signed-off-by: Romain Naour <romain.naour@skf.com>
> > > 
> > > Should this get a Fixes: tag and be also applied to the stable series?
> > 
> > The current behavior can be reproduced on any released kernel (at least since
> > 6.1). But I'm not sure if it should be backported to stable kernels since it
> > delays the ima/evm initialization at runtime.
> 
> With the IMA builtin measurement policy specified on the boot command line
> ("ima_policy=tcb"), moving init_ima from the late_initcall() to
> late_initcall_sync() affects the measurement list order.  It's unlikely, but
> possible, that someone is sealing the TPM to PCR-10.  It's probably not a good
> idea to backport the change.
> 
> An alternative would be to continue using the late_initcall(), but retry on
> failure, instead of going directly into TPM-bypass mode.
> 
> As far as I can tell, everything is still being measured and verified, but more
> testing is required.

Romain, Paul, another report of IMA going into TPM-bypass mode is here: 
https://github.com/raspberrypi/linux/issues/6217.  Deferring IMA initialization
to late_initcall_sync() did not resolve the problem for them.  Please take a
look at the report.

thanks,

Mimi