Hi, > > > > On Thu, 2026-04-23 at 06:55 +0100, Yeoreum Yun wrote: > > > > > > On Wed, 2026-04-22 at 20:41 +0100, Yeoreum Yun wrote: > > > > > > > > Hi Mimi, > > > > > > > > > > > > > > > > > On Wed, 2026-04-22 at 17:24 +0100, Yeoreum Yun wrote: > > > > > > > > > > To generate the boot_aggregate log in the IMA subsystem > > > > > > > > > > with TPM PCR values, > > > > > > > > > > the TPM driver must be built as built-in and > > > > > > > > > > must be probed before the IMA subsystem is initialized. > > > > > > > > > > > > > > > > > > > > However, when the TPM device operates over the FF-A > > > > > > > > > > protocol using > > > > > > > > > > the CRB interface, probing fails and returns -EPROBE_DEFER > > > > > > > > > > if > > > > > > > > > > the tpm_crb_ffa device — an FF-A device that provides the > > > > > > > > > > communication > > > > > > > > > > interface to the tpm_crb driver — has not yet been probed. > > > > > > > > > > > > > > > > > > > > To ensure the TPM device operating over the FF-A protocol > > > > > > > > > > with > > > > > > > > > > the CRB interface is probed before IMA initialization, > > > > > > > > > > the following conditions must be met: > > > > > > > > > > > > > > > > > > > > 1. The corresponding ffa_device must be registered, > > > > > > > > > > which is done via ffa_init(). > > > > > > > > > > > > > > > > > > > > 2. The tpm_crb_driver must successfully probe this > > > > > > > > > > device via > > > > > > > > > > tpm_crb_ffa_init(). > > > > > > > > > > > > > > > > > > > > 3. The tpm_crb driver using CRB over FF-A can then > > > > > > > > > > be probed successfully. (See crb_acpi_add() and > > > > > > > > > > tpm_crb_ffa_init() for reference.) > > > > > > > > > > > > > > > > > > > > Unfortunately, ffa_init(), tpm_crb_ffa_init(), and > > > > > > > > > > crb_acpi_driver_init() are > > > > > > > > > > all registered with device_initcall, which means > > > > > > > > > > crb_acpi_driver_init() may > > > > > > > > > > be invoked before ffa_init() and tpm_crb_ffa_init() are > > > > > > > > > > completed. > > > > > > > > > > > > > > > > > > > > When this occurs, probing the TPM device is deferred. > > > > > > > > > > However, the deferred probe can happen after the IMA > > > > > > > > > > subsystem > > > > > > > > > > has already been initialized, since IMA initialization is > > > > > > > > > > performed > > > > > > > > > > during late_initcall, and deferred_probe_initcall() is > > > > > > > > > > performed > > > > > > > > > > at the same level. > > > > > > > > > > > > > > > > > > > > To resolve this, call ima_init() again at late_inicall_sync > > > > > > > > > > level > > > > > > > > > > so that let IMA not miss TPM PCR value when generating > > > > > > > > > > boot_aggregate > > > > > > > > > > log though TPM device presents in the system. > > > > > > > > > > > > > > > > > > > > Signed-off-by: Yeoreum Yun <[email protected]> > > > > > > > > > > > > > > > > > > A lot of change for just detecting whether ima_init() is > > > > > > > > > being called on > > > > > > > > > late_initcall or late_initcall_sync(), without any > > > > > > > > > explanation for all the other > > > > > > > > > changes (e.g. ima_init_core). > > > > > > > > > > > > > > > > > > Please just limit the change to just calling ima_init() twice. > > > > > > > > > > > > > > > > My concern is that ima_update_policy_flags() will be called > > > > > > > > when ima_init() is deferred -- not initialised anything. > > > > > > > > though functionally, it might be okay however, > > > > > > > > I think ima_update_policy_flags() and notifier should work > > > > > > > > after ima_init() > > > > > > > > works logically. > > > > > > > > > > > > > > > > This change I think not much quite a lot. just wrapper > > > > > > > > ima_init() with > > > > > > > > ima_init_core() with some error handling. > > > > > > > > > > > > > > > > Am I missing something? > > > > > > > > > > > > > > Also, if we handle in ima_init() only, but it failed with other > > > > > > > reason, > > > > > > > we shouldn't call again ima_init() in the late_initcall_sync. > > > > > > > > > > > > > > To handle this, It wouldn't do in the ima_init() but we need to > > > > > > > handle > > > > > > > it by caller of ima_init(). > > > > > > > > > > > > Only tpm_default_chip() is being called to set the ima_tpm_chip. > > > > > > On failure, > > > > > > instead of going into TPM-bypass mode, return immediately. There > > > > > > are no calls > > > > > > to anything else. Just call ima_init() a second time. > > > > > > > > > > I’m not fully convinced this is sufficient. > > > > > > > > > > What I meant is the case where ima_init() fails due to other > > > > > initialisation steps, not only tpm_default_chip() (e.g. > > > > > ima_fs_init()). > > > > > > > > The purpose of THIS patch is to add late_initcall_sync, when the TPM is > > > > not > > > > available at late_initcall. This would be classified as a bug fix and > > > > would be > > > > backported. No other changes should be included in this patch. > > > > > > Okay. > > > > > > > > > > > > > I’d also like to ask again whether it is fine to call > > > > > ima_update_policy_flags() and keep the notifier registered in the > > > > > deferred TPM case. While this may be functionally acceptable, it seems > > > > > logically questionable to do so when ima_init() has not completed. > > > > > > > > Other than extending the TPM, IMA should behave exactly the same > > > > whether there > > > > is a TPM or goes into TPM-bypass mode. > > > > > > > > > > > > > > There is also a possibility that a deferred case ultimately fails > > > > > (e.g. > > > > > deferred at late_initcall, but then failing at late_initcall_sync > > > > > for another reason, even while entering TPM bypass mode). In that > > > > > case, > > > > > it seems more appropriate to handle this state in the caller of > > > > > ima_init(), rather than inside ima_init() itself. > > > > > > > > If the TPM isn't found at late_initcall_sync(), then IMA should go into > > > > TPM- > > > > bypass mode. Please don't make any other changes to the existing IMA > > > > behavior > > > > and hide it here behind the late_initcall_sync change. > > > > > > Okay. you're talking called ima_update_policy_flags() at late_initcall > > > wouldn't be not a problem even in case of late_initcall_sync's ima_init() > > > get failed with "TPM-bypass mode". > > > > > > I see then, I'll make a patch simpler then. > > > > But I think in case of below situation: > > - late_initcall's first ima_init() is deferred. > > - late_initcall_sync try again but failed and try again with > > CONFIG_IMA_DEFAULT_HASH. > > > > I would like to sustain init_ima_core to reduce the same code repeat > > in late_initcall_sync. > > I think what Mimi's proposing is: > > If we're in late_initcall, and the TPM isn't available, return immediately > with an error (the EPROBE_DEFER?), don't do any init. > > If we're in late_initcall_sync, either we're already initialised, so do > return and nothing, or run through the entire flow, even if the TPM isn't > unavailable. > > So ima_init() just needs to know a) if it's in the sync or non-sync mode and > b) for the sync mode, if we've already done the init at > non-sync.
But think think about when "late_initcall_sync" happens. In case of it, whether TPM present or by-pass mode, if it failed, it try again with the DEFAULT_HASH if hash isn't use DEFAULT one (e.x. user set boot arguments hash_setup=md5). IOW, late_initcall_sync should call twice just like former code do this. I mean to wrap this duplication of code with init_core_ima(). so that int late_initcall_sync in case of deferred case to try agina ima_init() with the DEFAULT HASH. -- Sincerely, Yeoreum Yun
