From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
To: Michael Ellerman <michael@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
Vivek Goyal <vgoyal@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Stewart Smith <stewart@linux.vnet.ibm.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
bhe@redhat.com, linuxppc-dev@lists.ozlabs.org,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Samuel Mendoza-Jonas <sam@mendozajonas.com>,
Dave Young <dyoung@redhat.com>,
linux-arm-kernel@lists.infradead.org,
Jeremy Kerr <jeremy.kerr@au1.ibm.com>
Subject: Re: [RFC 0/3] extend kexec_file_load system call
Date: Fri, 22 Jul 2016 17:41:40 -0300 [thread overview]
Message-ID: <1732711.nTAkJm8nA3@hactar> (raw)
In-Reply-To: <878twutmaj.fsf@concordia.ellerman.id.au>
Am Freitag, 22 Juli 2016, 12:54:28 schrieb Michael Ellerman:
> Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> writes:
> > So even if not ideal, the solution above is desirable for powerpc. We
> > would like to preserve the ability of allowing userspace to pass
> > parameters to the OS via the DTB, even if secure boot is enabled.
> >
> > I would like to turn the above into a proposal:
> >
> > Extend the syscall as shown in this RFC from Takahiro AKASHI, but
> > instead of accepting a complete DTB from userspace, the syscall accepts
> > a DTB containing only a /chosen node. If the DTB contains any other
> > node, the syscall fails with EINVAL. If the DTB contains any subnode in
> > /chosen, or if there's a compatible or device_type property in /chosen,
> > the syscall fails with EINVAL as well.
> >
> > The kernel can then add the properties in /chosen to the device tree
> > that it will pass to the next kernel.
> >
> > What do you think?
>
> I think we will inevitably have someone who wants to pass something
> other than a child of /chosen.
>
> At that point we would be faced with adding yet another syscall, or at
> best a new flag.
>
> I think we'd be better allowing userspace to pass a DTB, and having an
> explicit whitelist (in the kernel) of which nodes & properties are
> allowed in that DTB.
Sounds good to me.
> For starters it would only contain /chosen/stdout-path (for example).
> But we would be able to add new nodes & properties in future.
If we allow things outside of chosen, we can keep the offb.c hook in
Petitboot and whitelist the framebuffer properties it adds to the vga node.
> The downside is userspace would have no way of detecting the content of
> the white list, other than trial and error. But in practice I'm not sure
> that would be a big problem.
For our use case in OpenPower I don't think it would be a problem, since the
userspace and the kernel are developed together.
--
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center
next prev parent reply other threads:[~2016-07-22 20:41 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
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 [this message]
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
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