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Subject: Re: [PATCH 1/3] IMA: add policy condition to measure duplicate
 critical data
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Tushar Sugandhi <tusharsu@linux.microsoft.com>,
        stephen.smalley.work@gmail.com, casey@schaufler-ca.com,
        agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.com,
        paul@paul-moore.com
Cc:     tyhicks@linux.microsoft.com, sashal@kernel.org, jmorris@namei.org,
        nramas@linux.microsoft.com, linux-integrity@vger.kernel.org,
        selinux@vger.kernel.org, linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org, dm-devel@redhat.com
Date:   Mon, 08 Feb 2021 15:45:27 -0500
In-Reply-To: <20210130004519.25106-2-tusharsu@linux.microsoft.com>
References: <20210130004519.25106-1-tusharsu@linux.microsoft.com>
         <20210130004519.25106-2-tusharsu@linux.microsoft.com>
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Hi Tushar,

On Fri, 2021-01-29 at 16:45 -0800, Tushar Sugandhi wrote:
> IMA needs to support duplicate measurements of integrity
> critical data to accurately determine the current state of that data
> on the system.  Further, since measurement of duplicate data is not
> required for all the use cases, it needs to be policy driven.
> 
> Define "allow_dup", a new IMA policy condition, for the IMA func
> CRITICAL_DATA to allow duplicate buffer measurement of integrity
> critical data.
> 
> Limit the ability to measure duplicate buffer data when action is
> "measure" and func is CRITICAL_DATA.

Why?!

> 
> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
> ---
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 9b45d064a87d..b89eb768dd05 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -35,6 +35,7 @@
>  #define IMA_FSNAME	0x0200
>  #define IMA_KEYRINGS	0x0400
>  #define IMA_LABEL	0x0800
> +#define IMA_ALLOW_DUP	0x1000
>  
>  #define UNKNOWN		0
>  #define MEASURE		0x0001	/* same as IMA_MEASURE */
> @@ -87,6 +88,7 @@ struct ima_rule_entry {
>  	char *fsname;
>  	struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
>  	struct ima_rule_opt_list *label; /* Measure data grouped under this label */

Defining a new boolean entry shouldn't be necessary.    The other
boolean values are just stored in "flags".

>  	struct ima_template_desc *template;
>  };

thanks,

Mimi