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SubjectRe: [PATCH 3/6] firmware: differentiate between signed regulatory.db and other firmware
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On Fri, 2018-05-04 at 00:07 +0000, Luis R. Rodriguez wrote:
> On Tue, May 01, 2018 at 09:48:20AM -0400, Mimi Zohar wrote:
> > Allow LSMs and IMA to differentiate between signed regulatory.db and
> > other firmware.
> >
> > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> > Cc: Luis R. Rodriguez <mcgrof@suse.com>
> > Cc: David Howells <dhowells@redhat.com>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Seth Forshee <seth.forshee@canonical.com>
> > Cc: Johannes Berg <johannes.berg@intel.com>
> > ---
> > drivers/base/firmware_loader/main.c | 5 +++++
> > include/linux/fs.h | 1 +
> > 2 files changed, 6 insertions(+)
> >
> > diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
> > index eb34089e4299..d7cdf04a8681 100644
> > --- a/drivers/base/firmware_loader/main.c
> > +++ b/drivers/base/firmware_loader/main.c
> > @@ -318,6 +318,11 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv)
> > break;
> > }
> >
> > +#ifdef CONFIG_CFG80211_REQUIRE_SIGNED_REGDB
> > + if ((strcmp(fw_priv->fw_name, "regulatory.db") == 0) ||
> > + (strcmp(fw_priv->fw_name, "regulatory.db.p7s") == 0))
> > + id = READING_FIRMWARE_REGULATORY_DB;
> > +#endif
>
> Whoa, no way.

There are two methods for the kernel to verify firmware signatures.
 If both are enabled, do we require both signatures or is one enough.
Assigning a different id for regdb signed firmware allows LSMs and IMA
to handle regdb files differently.

>
> > fw_priv->size = 0;
> > rc = kernel_read_file_from_path(path, &fw_priv->data, &size,
> > msize, id);
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index dc16a73c3d38..d1153c2884b9 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -2811,6 +2811,7 @@ extern int do_pipe_flags(int *, int);
> > id(FIRMWARE, firmware) \
> > id(FIRMWARE_PREALLOC_BUFFER, firmware) \
> > id(FIRMWARE_FALLBACK, firmware) \
> > + id(FIRMWARE_REGULATORY_DB, firmware) \
>
> Why could IMA not appriase these files? They are part of the standard path.

The subsequent patch attempts to verify the IMA-appraisal signature,
but on failure it falls back to allowing regdb signatures.  For
systems that only want to load firmware based on IMA-appraisal, then
regdb wouldn't be enabled.

Mimi

>
> > id(MODULE, kernel-module) \
> > id(KEXEC_IMAGE, kexec-image) \
> > id(KEXEC_INITRAMFS, kexec-initramfs) \
> > --
> > 2.7.5
> >
> >
>

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