From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@lists.ozlabs.org
Cc: Dave Young <dyoung@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org, bhe@redhat.com,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
bauerman@linux.vnet.ibm.com, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [RFC 0/3] extend kexec_file_load system call
Date: Wed, 13 Jul 2016 10:01:33 +0200 [thread overview]
Message-ID: <5352106.oQ0Ff9gWJA@wuerfel> (raw)
In-Reply-To: <20160713023614.GB3222@dhcp-128-65.nay.redhat.com>
On Wednesday, July 13, 2016 10:36:14 AM CEST Dave Young wrote:
> On 07/12/16 at 03:50pm, Mark Rutland wrote:
> > On Tue, Jul 12, 2016 at 04:24:10PM +0200, Arnd Bergmann wrote:
> > > On Tuesday, July 12, 2016 10:18:11 AM CEST Vivek Goyal wrote:
> >
> > /proc/devicetree (aka /sys/firmware/devicetree) is a filesystem derived
> > from the raw DTB (which is exposed at /sys/firmware/fdt).
> >
> > The blob that was handed to the kernel at boot time is exposed at
> > /sys/firmware/fdt.
>
> I believe the blob can be read and passed to kexec kernel in kernel code without
> the extra fd.
>
> But consider we can kexec to a different kernel and a different initrd so there
> will be use cases to pass a total different dtb as well. From my understanding
> it is reasonable but yes I think we should think carefully about the design.
Ok, I can see four interesting use cases here:
- Using the dtb that the kernel has saved at boot time. Ideally this should not
require an additional step of signing it, since the running kernel already
trusts it.
- A dtb blob from the file system that was produced along with the kernel image.
If we require a signature on the kernel, the the same requirement should be
made on the dtb. Whoever signs the kernel can also sign the dtb.
The tricky part here is the kernel command line that is part of the dtb
and that may need to be modified.
- Modifying the dtb at for any of the reasons I listed: This should always
be possible when we do not use secure boot, just like booting an unsigned
kernel is.
- kboot/petitboot with all of the user space being part of the trusted boot
chain: it would be good to allow these to modify the dtb as needed without
breaking the trust chain, just like we allow grub or u-boot to modify the dtb
before passing it to the kernel.
Arnd
next prev parent reply other threads:[~2016-07-13 8:02 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 1:41 [RFC 0/3] extend kexec_file_load system call AKASHI Takahiro
2016-07-12 1:41 ` [RFC 1/3] syscall: add kexec_file_load to generic unistd.h AKASHI Takahiro
2016-07-12 1:42 ` [RFC 2/3] kexec: add dtb info to struct kimage AKASHI Takahiro
2016-07-12 1:42 ` [RFC 3/3] kexec: extend kexec_file_load system call AKASHI Takahiro
2016-07-15 13:09 ` Vivek Goyal
2016-07-15 13:19 ` Mark Rutland
2016-07-18 2:30 ` Dave Young
2016-07-18 10:07 ` Mark Rutland
2016-07-19 0:55 ` Dave Young
2016-07-19 10:52 ` Mark Rutland
2016-07-19 12:24 ` Vivek Goyal
2016-07-19 12:47 ` Mark Rutland
2016-07-19 13:26 ` Vivek Goyal
2016-07-20 11:41 ` David Laight
2016-07-21 9:21 ` Russell King - ARM Linux
2016-07-18 2:33 ` Dave Young
2016-07-27 0:24 ` [PATCH v2 " Thiago Jung Bauermann
2016-08-05 20:46 ` Thiago Jung Bauermann
2016-07-12 13:25 ` [RFC 0/3] " Eric W. Biederman
2016-07-12 13:58 ` Thiago Jung Bauermann
2016-07-12 14:02 ` Vivek Goyal
2016-07-12 23:45 ` Stewart Smith
2016-07-13 13:27 ` Vivek Goyal
2016-07-12 14:02 ` Arnd Bergmann
2016-07-12 14:18 ` Vivek Goyal
2016-07-12 14:24 ` Arnd Bergmann
2016-07-12 14:50 ` Mark Rutland
2016-07-13 2:36 ` Dave Young
2016-07-13 8:01 ` Arnd Bergmann [this message]
2016-07-13 8:23 ` Stewart Smith
2016-07-13 9:41 ` Mark Rutland
2016-07-13 13:13 ` Arnd Bergmann
2016-07-13 18:45 ` Thiago Jung Bauermann
2016-07-13 19:59 ` Arnd Bergmann
2016-07-14 2:18 ` Thiago Jung Bauermann
2016-07-14 8:29 ` Arnd Bergmann
2016-07-15 1:44 ` Thiago Jung Bauermann
2016-07-15 7:31 ` Arnd Bergmann
2016-07-15 13:26 ` Vivek Goyal
2016-07-15 13:33 ` Mark Rutland
2016-07-15 15:29 ` Thiago Jung Bauermann
2016-07-15 15:47 ` Mark Rutland
2016-07-15 13:42 ` Russell King - ARM Linux
2016-07-15 20:26 ` Arnd Bergmann
2016-07-15 21:03 ` Thiago Jung Bauermann
2016-07-22 0:09 ` Thiago Jung Bauermann
2016-07-22 0:53 ` Jeremy Kerr
2016-07-22 2:54 ` Michael Ellerman
2016-07-22 20:41 ` Thiago Jung Bauermann
2016-07-15 8:49 ` Russell King - ARM Linux
2016-07-15 13:03 ` Vivek Goyal
2016-07-13 9:34 ` Mark Rutland
2016-07-13 17:38 ` AKASHI Takahiro
2016-07-13 17:58 ` Mark Rutland
2016-07-13 19:57 ` Arnd Bergmann
2016-07-14 12:42 ` Mark Rutland
2016-07-14 1:54 ` Dave Young
2016-07-14 1:50 ` Dave Young
2016-07-12 16:25 ` Thiago Jung Bauermann
2016-07-12 20:58 ` Petr Tesarik
2016-07-12 21:22 ` Eric W. Biederman
2016-07-12 21:36 ` Eric W. Biederman
2016-07-12 21:53 ` Petr Tesarik
2016-07-12 22:18 ` Russell King - ARM Linux
2016-07-13 4:59 ` Stewart Smith
2016-07-13 7:36 ` Russell King - ARM Linux
2016-07-13 7:47 ` Ard Biesheuvel
2016-07-13 8:09 ` Russell King - ARM Linux
2016-07-13 8:20 ` Stewart Smith
2016-07-13 7:55 ` Stewart Smith
2016-07-13 8:26 ` Russell King - ARM Linux
2016-07-13 8:36 ` Dave Young
2016-07-13 8:57 ` Petr Tesarik
2016-07-13 13:03 ` Vivek Goyal
2016-07-13 17:40 ` Russell King - ARM Linux
2016-07-13 18:22 ` Vivek Goyal
2016-07-18 12:46 ` Balbir Singh
2016-07-18 13:26 ` Vivek Goyal
2016-07-18 13:38 ` Vivek Goyal
2016-07-20 3:45 ` Balbir Singh
2016-07-20 8:35 ` Russell King - ARM Linux
2016-07-20 11:12 ` Arnd Bergmann
2016-07-20 15:50 ` Thiago Jung Bauermann
2016-07-20 12:46 ` Vivek Goyal
2016-07-20 12:27 ` Vivek Goyal
2016-07-12 23:41 ` Stewart Smith
2016-07-13 13:25 ` Vivek Goyal
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5352106.oQ0Ff9gWJA@wuerfel \
--to=arnd@arndb.de \
--cc=bauerman@linux.vnet.ibm.com \
--cc=bhe@redhat.com \
--cc=dyoung@redhat.com \
--cc=ebiederm@xmission.com \
--cc=kexec@lists.infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mark.rutland@arm.com \
--cc=takahiro.akashi@linaro.org \
--cc=vgoyal@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).