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Subject: Re: [RFC PATCH v1] ima: verify mprotect change is consistent with
 mmap policy
To:     Mimi Zohar <zohar@linux.ibm.com>, linux-integrity@vger.kernel.org
Cc:     Casey Schaufler <casey@schaufler-ca.com>,
        Jann Horn <jannh@google.com>,
        Stephen Smalley <stephen.smalley.work@gmail.com>,
        Eric Biggers <ebiggers@kernel.org>,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1588699845-6196-1-git-send-email-zohar@linux.ibm.com>
From:   Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Message-ID: <2ae3adf2-25cb-eb6f-4615-85e3ac493161@linux.microsoft.com>
Date:   Tue, 5 May 2020 10:52:12 -0700
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On 5/5/20 10:30 AM, Mimi Zohar 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.
> 
> On mprotect change success, return 0.  On failure, return -EACESS.
> 
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
> Changelog v1:
> - Reverse tests to remove code indentation. (Lakshmi Ramasubramanian)
> - General code cleanup, including adding comments.
> 
>   include/linux/ima.h               |  7 ++++++
>   security/integrity/ima/ima_main.c | 51 +++++++++++++++++++++++++++++++++++++++
>   security/security.c               |  7 +++++-
>   3 files changed, 64 insertions(+), 1 deletion(-)

Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>