linux-kernel - Re: [PATCH] Ask user input only when CONFIG_X86 or CONFIG_COMPILE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20191011125446.GA2170@localhost.localdomain>
Date:   Fri, 11 Oct 2019 12:55:12 +0000
From:   <Narendra.K@...l.com>
To:     <geert@...ux-m68k.org>
CC:     <ard.biesheuvel@...aro.org>, <linux-efi@...r.kernel.org>,
        <Mario.Limonciello@...l.com>, <tglx@...utronix.de>,
        <linux-kernel@...r.kernel.org>, <james.morse@....com>,
        <mingo@...nel.org>
Subject: Re: [PATCH] Ask user input only when CONFIG_X86 or
 CONFIG_COMPILE_TEST is set to y

On Fri, Oct 11, 2019 at 12:01:25PM +0200, Geert Uytterhoeven wrote:
> > > > > > -       bool "EFI Runtime Configuration Interface Table Version 2 Support"
> > > > > > +       bool
> > > > > > +       prompt "EFI RCI Table Version 2 Support" if X86 || COMPILE_TEST
> > >
> > > Why the split of bool and prompt?
> > > Why not simply add a single line "depends on X86 || COMPILE_TEST"?
> >
> > It is because of the findings shared in [1]. Please let me know your
> > thoughts on the findings.
> 
> So you want to prevent the user from seeing a prompt for an option he may
> or may not need to enable, when running "make oldconfig"?

Geert,

> The code in question is entirely architecture agnostic, and defaults
> to 'n', so I am not convinced this is needed. (It came up in the
> review as well)

>> "make oldconfig" still asks me the question on e.g. arm64, where it is
>> irrelevant, until arm64 variants of the hardware show up.

>> So IMHO it should have "depends on X86 || COMPILE_TEST".

>From the discussion in [1] and [2](pasted a part of it above), my understanding
of the issue you reported is that 'make oldconfig' asks the user a question for arm64
though the EFI_RCI2_TABLE is not relevant for arm64. From the tests,
it seemed like adding "depends on X86 || COMPILE_TEST" does not fix the
issue, splitting bool into bool + prompt fixes it.

Please let me know if I am missing any detail in the issue you reported.  

With the way EFI_RCI2_TABLE is currently defined, my understanding is
that 'make oldconfig' does not set the EFI_RCI2_TABLE to 'y' by default
on arm64, but it asks the user the question. User has to say 'y' if he
wants it to be set to 'y', else by default 'n' is set. This behavior is
as expected. 

> 
> One common approach is to let the Kconfig symbol for the platform (not for
> all of X86!) select EFI_RCI2_TABLE.
> That way it will be enabled automatically when needed.

We did not intend to enable EFI_RCI2_TABLE option by default even on all
X86 systems from the begining. As a result, we chose to set it to 'n' by
default and added the guidance in 'help' section to say 'y' for Dell EMC
PowerEdge systems. 

> 
> Another approach is to not force the option on, but guide the user towards
> enabling it, by adding "default y if <platform_symbol>".

As mentioned above, we want to keep the default to n.

> Without the "|| COMPILE_TEST", you cannot enable compile-testing of
> the driver on non-x86 platforms with EFI.

Ok. We could keep the check. Could we make it independent of platforms
by adding 'defbool y if COMPILE_TEST' ? 

[1] Re: [PATCH 4/5] efi: Export Runtime Configuration Interface table to sysfs
https://lore.kernel.org/linux-efi/20190812150452.27983-5-ard.biesheuvel@linaro.org/T/#m0d73b4fa0dd7ece5038e4c9580dcc4e2ce5bd63c

[2] Re: [PATCH 4/5] efi: Export Runtime Configuration Interface table to sysfs
https://lore.kernel.org/linux-efi/20190812150452.27983-5-ard.biesheuvel@linaro.org/T/#mf45a9bc1861c71f110c800a53c60f0be65c68ec7
-- 
With regards,
Narendra K