From: Kees Cook <email@example.com>
To: "firstname.lastname@example.org" <email@example.com>
Cc: Igor Stoppa <firstname.lastname@example.org>,
Ahmed Soliman <email@example.com>,
Kernel Hardening <firstname.lastname@example.org>,
Linux Kernel Mailing List <email@example.com>
Subject: Re: [RFC PATCH v4 00/12] hardening: statically allocated protected memory
Date: Mon, 11 Feb 2019 17:26:06 -0800 [thread overview]
Message-ID: <CAGXu5jLRJZuWjnwEuK=7AMeCrj-eioVGksPL9dE9pbzHM=+Rmg@mail.gmail.com> (raw)
On Mon, Feb 11, 2019 at 5:08 PM firstname.lastname@example.org
> On Tue, 12 Feb 2019, 4.47 Kees Cook <email@example.com wrote:
>> On Mon, Feb 11, 2019 at 4:37 PM Igor Stoppa <firstname.lastname@example.org> wrote:
>> > On 12/02/2019 02:09, Kees Cook wrote:
>> > > On Mon, Feb 11, 2019 at 3:28 PM Igor Stoppa <email@example.com> wrote:
>> > > It looked like only the memset() needed architecture support. Is there
>> > > a reason for not being able to implement memset() in terms of an
>> > > inefficient put_user() loop instead? That would eliminate the need for
>> > > per-arch support, yes?
>> > So far, yes, however from previous discussion about power arch, I
>> > understood this implementation would not be so easy to adapt.
>> > Lacking other examples where the extra mapping could be used, I did not
>> > want to add code without a use case.
>> > Probably both arm and x86 32 bit could do, but I would like to first get
>> > to the bitter end with memory protection (the other 2 thirds).
>> > Mostly, I hated having just one arch and I also really wanted to have arm64.
>> Right, I meant, if you implemented the _memset() case with put_user()
>> in this version, you could drop the arch-specific _memset() and shrink
>> the patch series. Then you could also enable this across all the
>> architectures in one patch. (Would you even need the Kconfig patches,
>> i.e. won't this "Just Work" on everything with an MMU?)
> I had similar thoughts, but this answer  deflated my hopes (if I understood it correctly).
> It seems that each arch needs to be massaged in separately.
True, but I think x86_64, x86, arm64, and arm will all be "normal".
power may be that way too, but they always surprise me. :)
Anyway, series looks good, but since nothing uses _memset(), it might
make sense to leave it out and put all the arch-enabling into a single
patch to cover the 4 archs above, in an effort to make the series even
next prev parent reply other threads:[~2019-02-12 1:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-11 23:27 [RFC PATCH v4 00/12] hardening: statically allocated protected memory Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 01/12] __wr_after_init: Core and default arch Igor Stoppa
2019-02-12 2:39 ` Matthew Wilcox
2019-02-12 7:20 ` Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 02/12] __wr_after_init: x86_64: memset_user() Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 03/12] __wr_after_init: x86_64: randomize mapping offset Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 04/12] __wr_after_init: x86_64: enable Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 05/12] __wr_after_init: arm64: memset_user() Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 06/12] __wr_after_init: arm64: enable Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 07/12] __wr_after_init: Documentation: self-protection Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 08/12] __wr_after_init: lkdtm test Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 09/12] __wr_after_init: rodata_test: refactor tests Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 10/12] __wr_after_init: rodata_test: test __wr_after_init Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 11/12] __wr_after_init: test write rare functionality Igor Stoppa
2019-02-11 23:27 ` [RFC PATCH v4 12/12] IMA: turn ima_policy_flags into __wr_after_init Igor Stoppa
2019-02-12 0:09 ` [RFC PATCH v4 00/12] hardening: statically allocated protected memory Kees Cook
2019-02-12 0:37 ` Igor Stoppa
2019-02-12 0:46 ` Kees Cook
2019-02-12 1:08 ` igor.stoppa
2019-02-12 1:26 ` Kees Cook [this message]
2019-02-12 7:09 ` Igor Stoppa
2019-02-12 22:39 ` Kees Cook
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