All of lore.kernel.org
 help / color / mirror / Atom feed
From: "H. Peter Anvin" <hpa@zytor.com>
To: Paul Moore <pmoore@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	coreyb@linux.vnet.ibm.com, wad@chromium.org
Subject: Re: [PATCH] x86: remove the x32 syscall bitmask from syscall_get_nr()
Date: Fri, 15 Feb 2013 11:02:49 -0800	[thread overview]
Message-ID: <511E8659.6030601@zytor.com> (raw)
In-Reply-To: <20130215172143.12549.10292.stgit@localhost>

On 02/15/2013 09:21 AM, Paul Moore wrote:
> Commit fca460f95e928bae373daa8295877b6905bc62b8 simplified the x32
> implementation by creating a syscall bitmask, equal to 0x40000000, that
> could be applied to x32 syscalls such that the masked syscall number
> would be the same as a x86_64 syscall.  While that patch was a nice
> way to simplify the code, it went a bit too far by adding the mask to
> syscall_get_nr(); returning the masked syscall numbers can cause
> confusion with callers that expect syscall numbers matching the x32
> ABI, e.g. unmasked syscall numbers.
> 
> This patch fixes this by simply removing the mask from syscall_get_nr()
> while preserving the other changes from the original commit.  While
> there are several syscall_get_nr() callers in the kernel, most simply
> check that the syscall number is greater than zero, in this case this
> patch will have no effect.  Of those remaining callers, they appear
> to be few, seccomp and ftrace, and from my testing of seccomp without
> this patch the original commit definitely breaks things; the seccomp
> filter does not correctly filter the syscalls due to the difference in
> syscall numbers in the BPF filter and the value from syscall_get_nr().
> Applying this patch restores the seccomp BPF filter functionality on
> x32.
> 
> I've tested this patch with the seccomp BPF filters as well as ftrace
> and everything looks reasonable to me; needless to say general usage
> seemed fine as well.
> 

Hi... it isn't 100% clear from the description if you have audited *all*
the callers?

	-hpa



  reply	other threads:[~2013-02-15 19:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-15 17:21 Paul Moore
2013-02-15 19:02 ` H. Peter Anvin [this message]
2013-02-15 20:52   ` Paul Moore
2013-02-26 20:58 ` Paul Moore
2013-03-15 21:15   ` Paul Moore
2013-03-15 21:56     ` H. Peter Anvin
2013-03-15 22:18       ` H.J. Lu
2013-03-25 20:55         ` Paul Moore
2013-04-02 21:31           ` Paul Moore
2013-04-03  0:17 ` [tip:x86/urgent] " tip-bot for Paul Moore

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=511E8659.6030601@zytor.com \
    --to=hpa@zytor.com \
    --cc=coreyb@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pmoore@redhat.com \
    --cc=wad@chromium.org \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH] x86: remove the x32 syscall bitmask from syscall_get_nr()' \
    /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

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.