From: tytso@mit.edu (Theodore Y. Ts'o)
To: linux-security-module@vger.kernel.org
Subject: leaking path in android binder: set_nice
Date: Tue, 25 Sep 2018 22:58:08 -0400 [thread overview]
Message-ID: <20180926025808.GA3321@thunk.org> (raw)
In-Reply-To: <d38229cb-eb38-19fa-f5d6-30e6389ade3b@tycho.nsa.gov>
On Tue, Sep 25, 2018 at 01:52:57PM -0400, Stephen Smalley wrote:
> On 09/25/2018 01:27 PM, Tong Zhang wrote:
> > Kernel Version: 4.18.5
> >
> > Problem Description:
> >
> > When setting nice value, it is checked by LSM function security_task_setnice().
> > see kernel/sched/core.c:3972 SYSCALL_DEFINE1(nice, int, increment)
> >
> > We discovered a leaking path in android binder which allows using binder?s interface to change
> > a process?s nice value. This path is leaked from being monitored by LSM.
> > see drivers/android/binder.c:1107 binder_set_nice.
>
> Not sure you want to invoke the LSM hook (or at least the same hook) when
> binder is performing priority inheritance. There is a difference between a
> userspace process switching its own priority and the kernel binder driver
> performing it. IIUC, the can_nice() check is more about honoring
> RLIMIT_NICE than anything else.
I agree with Stephen; it doesn't make sense to subject the binder PI
mechanism to the LSM hook.
- Ted
WARNING: multiple messages have this Message-ID (diff)
From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Tong Zhang <ztong@vt.edu>,
gregkh@linuxfoundation.org, arve@android.com, tkjos@android.com,
maco@android.com, devel@driverdev.osuosl.org,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
Wenbo Shen <shenwenbosmile@gmail.com>
Subject: Re: leaking path in android binder: set_nice
Date: Tue, 25 Sep 2018 22:58:08 -0400 [thread overview]
Message-ID: <20180926025808.GA3321@thunk.org> (raw)
In-Reply-To: <d38229cb-eb38-19fa-f5d6-30e6389ade3b@tycho.nsa.gov>
On Tue, Sep 25, 2018 at 01:52:57PM -0400, Stephen Smalley wrote:
> On 09/25/2018 01:27 PM, Tong Zhang wrote:
> > Kernel Version: 4.18.5
> >
> > Problem Description:
> >
> > When setting nice value, it is checked by LSM function security_task_setnice().
> > see kernel/sched/core.c:3972 SYSCALL_DEFINE1(nice, int, increment)
> >
> > We discovered a leaking path in android binder which allows using binder’s interface to change
> > a process’s nice value. This path is leaked from being monitored by LSM.
> > see drivers/android/binder.c:1107 binder_set_nice.
>
> Not sure you want to invoke the LSM hook (or at least the same hook) when
> binder is performing priority inheritance. There is a difference between a
> userspace process switching its own priority and the kernel binder driver
> performing it. IIUC, the can_nice() check is more about honoring
> RLIMIT_NICE than anything else.
I agree with Stephen; it doesn't make sense to subject the binder PI
mechanism to the LSM hook.
- Ted
next prev parent reply other threads:[~2018-09-26 2:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 17:27 leaking path in android binder: set_nice Tong Zhang
2018-09-25 17:27 ` Tong Zhang
2018-09-25 17:38 ` Greg KH
2018-09-25 17:38 ` Greg KH
2018-09-25 17:52 ` Stephen Smalley
2018-09-25 17:52 ` Stephen Smalley
2018-09-26 2:58 ` Theodore Y. Ts'o [this message]
2018-09-26 2:58 ` Theodore Y. Ts'o
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=20180926025808.GA3321@thunk.org \
--to=tytso@mit.edu \
--cc=linux-security-module@vger.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 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.