[PATCH] keys: set persistent keyring timeout before destination linking

[Karl Mehltretter]

On Tue, Sep 01, 2026 at 04:30:27PM +0100, Jarkko Sakkinen wrote:
> > Tested with QEMU 10.2.1 TCG. The reproducer set
> > /proc/sys/kernel/keys/persistent_keyring_expiry to 60 seconds, restricted
> > the destination with KEYCTL_RESTRICT_KEYRING, and then called
> > KEYCTL_GET_PERSISTENT. No LSM policy was loaded.
> > 
> >                       syscall result  /proc/keys expiry
> >   i386 baseline       -EPERM          perm
> >   i386 patched        -EPERM          1m
> >   x86_64 patched      -EPERM          1m
> > 
> > Full kernel builds completed for i386 and ARM926, and for x86_64 with
> > CONFIG_PROVE_LOCKING=y. The x86_64 reproducer completed without lockdep
> > reports, warnings, or bugs.
> 
> Please describe this in the commit message and delete most of
> the text it has. This is the motivation part.

Got it, thanks. I'll shorten commit message.

I also found a narrow race if linking is delayed past expiry and GC runs.
It is unlikely in practice, but reproducible with an injected delay, so
I'll address it in v2.

Thanks,
Karl