[PATCH] ima: debugging late_initcall_sync measurements

[Mimi Zohar]

On Fri, 2026-05-01 at 12:52 -0400, David Safford wrote:
> On Thu, Apr 30, 2026 at 5:43 PM Mimi Zohar <zohar at linux.ibm.com> wrote:
> > 
> > On Thu, 2026-04-30 at 10:48 +0100, Yeoreum Yun wrote:
> > > With above change I confirmed there is no meaurement log
> > > between boot_aggregate and boot_aggregate_late except "kernel_version"
> > > But this is ignorable since this UTS measurement is done in
> > > "ima_init_core() (old: ima_init())" and it is part of ima initialisation.
> > > 
> > > 1. ima_policy=tcb
> > > 
> > >   # cat /sys/kernel/security/ima/ascii_runtime_measurements
> > >   10 0adefe762c149c7cec19da62f0da1297fcfbffff ima-ng sha256:0000000000000000000000000000000000000000000000000000000000000000 boot_aggregate
> > >   10 4e5d73ebadfd8f850cb93ce4de755ba148a9a7d5 ima-ng sha256:0000000000000000000000000000000000000000000000000000000000000000 boot_aggregate_late
> > >   10 7c23cc970eceec906f7a41bc2fbde770d7092209 ima-ng sha256:72ade6ae3d35cfe5ede7a77b1c0ed1d1782a899445fdcb219c0e994a084a70d5 /bin/busybox
> snip
> > > 
> > > 2. ima_policy=critical_data
> > > 
> > >   # cat /sys/kernel/security/ima/ascii_runtime_measurements
> > >   10 0adefe762c149c7cec19da62f0da1297fcfbffff ima-ng sha256:0000000000000000000000000000000000000000000000000000000000000000 boot_aggregate
> > >   10 49ab61dd97ea2f759edcb6c6a3387ac67f0aa576 ima-buf sha256:0c907aab3261194f16b0c2a422a82f145bc9b9ecb8fdb633fa43e3e5379f0af2 kernel_version 372e312e302d7263312b // Ignorable since it's generated by ima_init(_core)().
> > >   10 4e5d73ebadfd8f850cb93ce4de755ba148a9a7d5 ima-ng sha256:0000000000000000000000000000000000000000000000000000000000000000 boot_aggregate_late
> > > 
> > > Therefore, init_ima() could move into late_initcall_sync like v1 did:
> > >   - https://lore.kernel.org/all/20260417175759.3191279-2-yeoreum.yun@arm.com/
> > 
> > Thanks, Yeoreum.  It's a bit premature to claim it's "safe" to move the
> > initcall.  Hopefully others will respond.
> > 
> > Mimi
> 
> I have also run with this patch on a number of bare metal and virtual machines,
> running everything from default Fedora 44 to a version with everything turned on
> (uefi secure boot, UKI with sdboot stub measurements, IMA measurement
> and appraisal enabled,
> all systemd measurements on, and systemd using the TPM for root
> partition decryption.)
> I too see only the kernel_version event between the normal and late
> calls, if ima_policy=critical_data.

Thanks, Dave!  Were all the systems you tested x86_64?  The next step would be
to test on different arch's (e.g. Z, Power).

Mimi