Re: [PATCH v1 1/1] certs: Explain the rational to call panic()

[Mickaël Salaün]

On 21/03/2022 19:23, Paul Moore wrote:
> On Mon, Mar 21, 2022 at 1:45 PM Mickaël Salaün <mic@xxxxxxxxxxx> wrote:
> > From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
> >
> > The blacklist_init() function calls panic() for memory allocation
> > errors.  This change documents the reason why we don't return -ENODEV.
> >
> > Suggested-by: Paul Moore <paul@xxxxxxxxxxxxxx> [1]
> > Requested-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> [1]
> > Link: https://lore.kernel.org/r/YjeW2r6Wv55Du0bJ@xxxxxx [1]
> > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
> > Link: https://lore.kernel.org/r/20220321174548.510516-2-mic@xxxxxxxxxxx
> > ---
> >   certs/blacklist.c | 8 ++++++++
> >   1 file changed, 8 insertions(+)
>
> I would suggest changing the second sentence as shown below, but
> otherwise it looks good to me.
>
> Reviewed-by: Paul Moore <paul@xxxxxxxxxxxxxx>
>
> > diff --git a/certs/blacklist.c b/certs/blacklist.c
> > index 486ce0dd8e9c..ac26bcf9b9a5 100644
> > --- a/certs/blacklist.c
> > +++ b/certs/blacklist.c
> > @@ -307,6 +307,14 @@ static int restrict_link_for_blacklist(struct key *dest_keyring,
> >
> >   /*
> >    * Initialise the blacklist
> > + *
> > + * The blacklist_init() function is registered as an initcall via
> > + * device_initcall().  As a result the functionality doesn't load and the
>
> "As a result if the blacklist_init() function fails for any reason the
> kernel continues to execute."

Thanks, I'll fix that.

> > + * kernel continues on executing.  While cleanly returning -ENODEV could be
> > + * acceptable for some non-critical kernel parts, if the blacklist keyring
> > + * fails to load it defeats the certificate/key based deny list for signed
> > + * modules.  If a critical piece of security functionality that users expect to
> > + * be present fails to initialize, panic()ing is likely the right thing to do.
> >    */
> >   static int __init blacklist_init(void)
> >   {
>
> --
> paul-moore.com