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From: Mimi Zohar <zohar@linux.ibm.com>
To: Jann Horn <jannh@google.com>
Cc: linux-integrity@vger.kernel.org,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	Eric Biggers <ebiggers@kernel.org>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] ima: verify mprotect change is consistent with mmap policy
Date: Tue, 05 May 2020 10:16:44 -0400	[thread overview]
Message-ID: <1588688204.5157.5.camel@linux.ibm.com> (raw)
In-Reply-To: <CAG48ez2PwqoDBx0pkZKFHvMXHNqAc8AfuTR5oPoF-obHqUo0zQ@mail.gmail.com>

Hi Jann,

On Tue, 2020-05-05 at 02:15 +0200, Jann Horn wrote:
> On Mon, May 4, 2020 at 11:18 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > Files can be mmap'ed read/write and later changed to execute to circumvent
> > IMA's mmap appraise policy rules.  Due to locking issues (mmap semaphore
> > would be taken prior to i_mutex), files can not be measured or appraised at
> > this point.  Eliminate this integrity gap, by denying the mprotect
> > PROT_EXECUTE change, if an mmap appraise policy rule exists.
> 
> Just keep in mind that there are other ways to create executable
> mappings containing controlled code; e.g. PROT_EXEC with
> MAP_ANONYMOUS, or writing to /proc/self/mem (which is a debugging API
> that works entirely without ever making the VMA writable - I had an
> old series to provide LSM hooks for that stuff at
> <https://lore.kernel.org/lkml/1478142286-18427-3-git-send-email-jann@thejh.net/>,
> but I guess I must have forgotten about it or something...).

Sure.  These sound like memory attacks, which should be closed, but
are probably out of scope for IMA.

thanks,

Mimi

      reply	other threads:[~2020-05-05 14:18 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04 21:17 Mimi Zohar
2020-05-04 22:51 ` Lakshmi Ramasubramanian
2020-05-05 15:33   ` Mimi Zohar
2020-05-05  0:15 ` Jann Horn
2020-05-05 14:16   ` Mimi Zohar [this message]

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