From: Tyler Hicks <tyhicks@canonical.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Paul Moore <paul@paul-moore.com>, Eric Paris <eparis@redhat.com>,
Kees Cook <keescook@chromium.org>, Will Drewry <wad@chromium.org>,
linux-audit@redhat.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
John Crispin <john@phrozen.org>
Subject: Re: [PATCH v3 1/4] seccomp: Add sysctl to display available actions
Date: Thu, 16 Feb 2017 14:05:41 -0600 [thread overview]
Message-ID: <5ebcdb7f-4aca-34a0-abbd-81eb5372776d@canonical.com> (raw)
In-Reply-To: <CALCETrV9NsTNRA_CqNTvqhE0WLDEBU8VjzPTaLOxcZ5XKc-4dw@mail.gmail.com>
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On 02/16/2017 01:01 PM, Andy Lutomirski wrote:
> On Thu, Feb 16, 2017 at 10:47 AM, Tyler Hicks <tyhicks@canonical.com> wrote:
>> On 02/15/2017 09:14 PM, Andy Lutomirski wrote:
>>> On Mon, Feb 13, 2017 at 7:45 PM, Tyler Hicks <tyhicks@canonical.com> wrote:
>>>> This patch creates a read-only sysctl containing an ordered list of
>>>> seccomp actions that the kernel supports. The ordering, from left to
>>>> right, is the lowest action value (kill) to the highest action value
>>>> (allow). Currently, a read of the sysctl file would return "kill trap
>>>> errno trace allow". The contents of this sysctl file can be useful for
>>>> userspace code as well as the system administrator.
>>>
>>> Would this make more sense as a new seccomp(2) mode a la
>>> SECCOMP_HAS_ACTION? Then sandboxy things that have no fs access could
>>> use it.
>>>
>>
>> It would make sense for code that needs to check which actions are
>> available. It wouldn't make sense for administrators that need to check
>> which actions are available unless libseccomp provided a wrapper utility.
>>
>> Is this a theoretical concern or do you know of a sandboxed piece of
>> code that cannot access the sysctl before constructing a seccomp filter?
>>
>
> It's semi-theoretical. But suppose I unshare namespaces, unmount a
> bunch of stuff, then ask libseccomp to install a filter. (I've
> written code that does exactly that.) libseccomp won't be able to
> read the sysctl.
That's a good point. It seems like we might need both mechanisms
(SECCOMP_HAS_ACTION for code and actions_avail for humans).
Tyler
>
> --Andy
>
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next prev parent reply other threads:[~2017-02-16 20:05 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 3:45 [PATCH v3 0/4] Improved seccomp logging Tyler Hicks
2017-02-14 3:45 ` [PATCH v3 1/4] seccomp: Add sysctl to display available actions Tyler Hicks
2017-02-16 1:00 ` Kees Cook
2017-02-16 18:43 ` Tyler Hicks
2017-02-16 3:14 ` Andy Lutomirski
2017-02-16 18:47 ` Tyler Hicks
2017-02-16 19:01 ` Andy Lutomirski
2017-02-16 20:05 ` Tyler Hicks [this message]
2017-02-14 3:45 ` [PATCH v3 2/4] seccomp: Add sysctl to configure actions that should be logged Tyler Hicks
2017-02-14 3:45 ` [PATCH v3 3/4] seccomp: Create an action to log before allowing Tyler Hicks
2017-02-14 3:45 ` [PATCH v3 4/4] seccomp: Add tests for SECCOMP_RET_LOG Tyler Hicks
2017-02-16 3:24 ` [PATCH v3 0/4] Improved seccomp logging Andy Lutomirski
2017-02-16 19:37 ` Tyler Hicks
2017-02-16 23:29 ` Kees Cook
2017-02-17 17:00 ` Andy Lutomirski
2017-02-22 18:39 ` Kees Cook
2017-02-22 18:46 ` Kees Cook
2017-04-07 22:16 ` Tyler Hicks
2017-04-07 22:46 ` Kees Cook
2017-04-07 23:46 ` Tyler Hicks
2017-04-11 3:59 ` Kees Cook
2017-04-27 22:17 ` Tyler Hicks
2017-04-27 23:42 ` Kees Cook
2017-05-02 2:41 ` Tyler Hicks
2017-05-02 16:14 ` Andy Lutomirski
2017-04-10 15:18 ` Steve Grubb
2017-04-10 15:57 ` Andy Lutomirski
2017-04-10 19:22 ` Tyler Hicks
2017-04-11 4:03 ` Kees Cook
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