linux-kernel - Re: [PATCH RFC v2 3/4] firmware: Add support for signature checks

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Date:	Fri, 23 Nov 2012 08:34:05 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	joeyli <jlee@...e.com>
Cc:	Matthew Garrett <mjg59@...f.ucam.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Jiri Kosina <jkosina@...e.cz>,
	David Howells <dhowells@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Ming Lei <tom.leiming@...il.com>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [PATCH RFC v2 3/4] firmware: Add support for signature checks

At Fri, 23 Nov 2012 14:56:11 +0800,
joeyli wrote:
> 
> 於 四，2012-11-08 於 18:35 +0100，Takashi Iwai 提到：
> > +#ifdef CONFIG_FIRMWARE_SIG
> > +static int verify_sig_file(struct firmware_buf *buf, const char
> > *path)
> > +{
> > +       const unsigned long markerlen = sizeof(FIRMWARE_SIG_STRING) -
> > 1;
> > +       struct file *file;
> > +       void *sig_data;
> > +       size_t sig_size;
> > +       int ret;
> > +
> > +       file = filp_open(path, O_RDONLY, 0);
> > +       if (IS_ERR(file))
> > +               return -ENOKEY;
> 
> I think there should return '-ENOENT', otherwise the firmware will show
> 'Invalid firmware signature' even didn't find the sig file.

Actually this is the intentional behavior.
In the secure boot mode, unsigned firmware should be rejected.

In the normal boot mode, the -ENOKEY error is ignored.  (Whether we
should taint the kernel with such an unsigned firmware is a bit
different question, though.)


thanks,

Takashi
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