From: Christoph Hellwig <hch@lst.de>
To: Dexuan Cui <decui@microsoft.com>
Cc: vkuznets <vkuznets@redhat.com>, Christoph Hellwig <hch@lst.de>,
Stephen Hemminger <stephen@networkplumber.org>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@amacapital.net>,
Michael Kelley <mikelley@microsoft.com>,
Ju-Hyoung Lee <juhlee@microsoft.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
KY Srinivasan <kys@microsoft.com>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: hv_hypercall_pg page permissios
Date: Tue, 16 Jun 2020 09:23:18 +0200 [thread overview]
Message-ID: <20200616072318.GA17600@lst.de> (raw)
In-Reply-To: <HK0P153MB0322EB3EE51073CC021D4AEABF9C0@HK0P153MB0322.APCP153.PROD.OUTLOOK.COM>
On Mon, Jun 15, 2020 at 07:49:41PM +0000, Dexuan Cui wrote:
> I did this experiment:
> 1. export vmalloc_exec and ptdump_walk_pgd_level_checkwx.
> 2. write a test module that calls them.
> 3. It turns out that every call of vmalloc_exec() triggers such a warning.
>
> vmalloc_exec() uses PAGE_KERNEL_EXEC, which is defined as
> (__PP|__RW| 0|___A| 0|___D| 0|___G)
>
> It looks the logic in note_page() is: for_each_RW_page, if the NX bit is unset,
> then report the page as an insecure W+X mapping. IMO this explains the
> warning?
It does. But it also means every other user of PAGE_KERNEL_EXEC
should trigger this, of which there are a few (kexec, tboot, hibernate,
early xen pv mapping, early SEV identity mapping)
We really shouldn't create mappings like this by default. Either we
need to flip PAGE_KERNEL_EXEC itself based on the needs of the above
users, or add another define to overload vmalloc_exec as there is no
other user of that for x86.
next prev parent reply other threads:[~2020-06-16 7:23 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 6:55 hv_hypercall_pg page permissios Christoph Hellwig
2020-04-07 7:28 ` Vitaly Kuznetsov
2020-04-07 7:38 ` Christoph Hellwig
2020-04-07 21:01 ` Andy Lutomirski
2020-06-12 7:48 ` Dexuan Cui
2020-06-15 8:35 ` Vitaly Kuznetsov
2020-06-15 17:41 ` Dexuan Cui
2020-06-15 19:49 ` Dexuan Cui
2020-06-16 7:23 ` Christoph Hellwig [this message]
2020-06-16 10:18 ` Peter Zijlstra
2020-06-16 10:23 ` Christoph Hellwig
2020-06-16 10:24 ` Christoph Hellwig
2020-06-16 10:31 ` Peter Zijlstra
2020-06-16 10:33 ` Christoph Hellwig
2020-06-16 10:40 ` Peter Zijlstra
2020-06-16 10:42 ` Christoph Hellwig
2020-06-16 10:52 ` Christoph Hellwig
2020-06-16 11:24 ` Peter Zijlstra
2020-06-16 14:39 ` Christoph Hellwig
2020-06-16 9:29 ` Vitaly Kuznetsov
2020-06-16 9:33 ` Christoph Hellwig
2020-06-16 9:55 ` Christoph Hellwig
2020-06-16 10:08 ` Christoph Hellwig
2020-06-16 10:50 ` Vitaly Kuznetsov
2020-06-16 10:20 ` Peter Zijlstra
2020-04-07 18:10 ` Dexuan Cui
2020-04-07 20:42 ` Wei Liu
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=20200616072318.GA17600@lst.de \
--to=hch@lst.de \
--cc=decui@microsoft.com \
--cc=juhlee@microsoft.com \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=luto@kernel.org \
--cc=mikelley@microsoft.com \
--cc=peterz@infradead.org \
--cc=stephen@networkplumber.org \
--cc=thomas.lendacky@amd.com \
--cc=vkuznets@redhat.com \
--cc=x86@kernel.org \
/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).