On Thu, 2024-08-01 at 12:12 +0200, Romain Naour wrote: > Hi Mimi, > > Le 11/07/2024 à 16:06, Mimi Zohar a écrit : > > 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@xxxxxxxx/ > > > > > > [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@xxxxxxx> > > > > > > > > > > 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. > > Indeed, it would be better if the IMA (and EVM) can use something like EPROBE_DEFER. Yes, "something like EPROBE_DEFER" sounds like the right direction. Depending on the environment, the TPM initialization delay might be acceptable and not introduce an integrity gap. For now let's start with just late_initcall() and late_initcall_sync(). If the TPM hasn't been initialized, not all of ima_init() needs to be deferred to late_initcall_sync(). > > > > > > > As far as I can tell, everything is still being measured and verified, but more > > > testing is required. > > Agree, I'm still evaluating the TPM stack when time allows. > > > > > 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. > > I don't think that the "mdelay(200)" is really needed when late_initcall_sync() > is used. I guess the issue was the spi driver was not builtin, fixed by: > > CONFIG_SPI_DESIGNWARE=y > CONFIG_SPI_DW_MMIO=y Good to know. thanks, Mimi
