Re: [PATCH net-next] modules: allow modprobe load regular elf binaries

[Alexei Starovoitov]

On 3/5/18 6:13 PM, Randy Dunlap wrote:
> Hi,
>
> On 03/05/2018 05:34 PM, Alexei Starovoitov wrote:
>
> > diff --git a/kernel/module.c b/kernel/module.c
> > index ad2d420024f6..6cfa35795741 100644
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
>
> > @@ -3669,6 +3683,17 @@ static int load_module(struct load_info *info, const char __user *uargs,
> >  	if (err)
> >  		goto free_copy;
> >
> > +	if (info->hdr->e_type == ET_EXEC) {
> > +#ifdef CONFIG_MODULE_SIG
> > +		if (!info->sig_ok) {
> > +			pr_notice_once("umh %s verification failed: signature and/or required key missing - tainting kernel\n",
>
> That's not a very friendly message to tell a user.  "umh" eh?

umh is an abbreviation known to kernel newbies:
https://kernelnewbies.org/KernelProjects/usermode-helper-enhancements

The rest of the message is copy paste of existing one.

> > +				       info->file->f_path.dentry->d_name.name);
> > +			add_taint(TAINT_UNSIGNED_MODULE, LOCKDEP_STILL_OK);
> > +		}
>
> And since the signature failed, why is it being loaded at all?

because this is how regular kernel modules deal with it.
sig_enforce is handled earlier.

> Is this in the "--force" load path?

--force forces modver and modmagic. These things don't apply here.