On Thu, 2026-04-23 at 15:03 +0100, Jonathan McDowell wrote: > On Thu, Apr 23, 2026 at 02:55:14PM +0100, Yeoreum Yun wrote: > > > On Thu, 2026-04-23 at 13:53 +0100, Jonathan McDowell wrote: > > > > On Thu, Apr 23, 2026 at 01:34:13PM +0100, Yeoreum Yun wrote: > > > > > > > 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. > > > > > > Thanks, Jonathan. That is exactly what I'm suggesting. Any other changes > > > should not be included in this patch. Since Yeoreum is not hearing me, > > > feel > > > free to post a patch. > > > > I see. so what you need to is this only > > If it looks good to you. I'll send it at v3. > > FWIW, I pulled the tpm_default_chip check out a level to account for the > extra init you mentioned, and have the following (completely untested or > compiled, but gives the approach):
Thanks, Jonathan! It looks good. Similarly untested/compiled. Emitting a message on failure to initialize IMA at late_initcall is good, but the attestation service won't know. Could you somehow differentiate between the late_initcall and late_initcall_sync boot_aggregate records? Mimi
