Re: [PATCH 1/2] module: export module signature enforcement status

From: Bruno E. O. Meneguele
Date: Mon Oct 23 2017 - 12:24:46 EST


On 23-10, Mimi Zohar wrote:
> On Fri, 2017-10-20 at 17:19 -0200, Bruno E. O. Meneguele wrote:
> > A static variable sig_enforce is used as status var to indicate the real
> > value of CONFIG_MODULE_SIG_FORCE, once this one is set the var will hold
> > true, but if the CONFIG is not set the status var will hold whatever
> > value is present in the module.sig_enforce kernel cmdline param: true
> > when =1 and false when =0 or not present.
> >
> > Considering this cmdline param take place over the CONFIG value when
> > it's not set, other places in the kernel could missbehave since they
>
> ^misbehave
>

right.

> > would have only the CONFIG_MODULE_SIG_FORCE value to rely on. Exporting
> > this status var allows the kernel to rely in the effective value of
> > module signature enforcement, being it from CONFIG value or cmdline
> > param.
>
> Thanks! There's a minor checkpatch warning below.
>
> > Signed-off-by: Bruno E. O. Meneguele <brdeoliv@xxxxxxxxxx>
> > ---
> > include/linux/module.h | 2 ++
> > kernel/module.c | 8 ++++++++
> > 2 files changed, 10 insertions(+)
> >
> > diff --git a/include/linux/module.h b/include/linux/module.h
> > index fe5aa3736707..ddfe17e3a85c 100644
> > --- a/include/linux/module.h
> > +++ b/include/linux/module.h
> > @@ -806,4 +806,6 @@ static inline bool module_sig_ok(struct module *module)
> > }
> > #endif /* CONFIG_MODULE_SIG */
> >
> > +bool is_module_sig_enforced(void);
> > +
> > #endif /* _LINUX_MODULE_H */
> > diff --git a/kernel/module.c b/kernel/module.c
> > index de66ec825992..b93c7ff44066 100644
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
> > @@ -278,6 +278,14 @@ static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
> > module_param(sig_enforce, bool_enable_only, 0644);
> > #endif /* !CONFIG_MODULE_SIG_FORCE */
> >
> > +/* Export sig_enforce kernel cmdline parameter to allow other subsystems rely
> > + * on that instead of directly to CONFIG_MODULE_SIG_FORCE config. */
>
> Checkpatch complains.  Please use the normal format:
> /*
>  *
>  */
>

Oh, sure, sorry for that! I'll resend a v2 of the patchset in a minute.

Thanks.

> > +bool is_module_sig_enforced(void)
> > +{
> > + return sig_enforce;
> > +}
> > +EXPORT_SYMBOL(is_module_sig_enforced);
> > +
> > /* Block module loading/unloading? */
> > int modules_disabled = 0;
> > core_param(nomodule, modules_disabled, bint, 0);
>

--
bmeneg
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