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From: Mimi Zohar <zohar@linux.ibm.com>
To: THOBY Simon <Simon.THOBY@viveris.fr>,
	"dmitry.kasatkin@gmail.com" <dmitry.kasatkin@gmail.com>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	BARVAUX Didier <Didier.BARVAUX@viveris.fr>
Subject: Re: [PATCH v4 4/5] IMA: add a policy option to restrict xattr hash algorithms on appraisal
Date: Tue, 27 Jul 2021 17:07:22 -0400	[thread overview]
Message-ID: <ecd666bdd278a0ca28b5fec10f4ac06932911f12.camel@linux.ibm.com> (raw)
In-Reply-To: <20210727163330.790010-5-simon.thoby@viveris.fr>

On Tue, 2021-07-27 at 16:33 +0000, THOBY Simon wrote:
> The kernel have the ability to restrict the set of hash algorithms

^kernel has

> it accepts for the security.ima xattr when it appraises files.
> 
> Define a new IMA policy rule option "appraise_hash=",
> using the mentionned mechanism to expose a user-toggable policy

^mentioned

> knob to opt-in to that restriction and select the desired set of
> algorithms that must be accepted.
> 
> When a policy rule uses the 'appraise_hash' option, appraisal of a
> file referenced by that rule will now fail if the digest algorithm
> employed to hash the file was not one of those explicitly listed
> in the option. In its absence, any hash algorithm compiled in the
> kernel will be accepted.
> 
> For example, on a system where SELinux is properly deployed, the rule
>   appraise func=BPRM_CHECK obj_type=iptables_exec_t appraise_hash=sha256,sha384
> will block the execution of iptables if the xattr security.ima of its
> executables were not hashed with either sha256 or sha384.
> 
> Signed-off-by: Simon Thoby <simon.thoby@viveris.fr>

Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

> ---

<snip>

> @@ -1204,6 +1228,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>  	entry->uid_op = &uid_eq;
>  	entry->fowner_op = &uid_eq;
>  	entry->action = UNKNOWN;
> +	entry->allowed_hashes = 0;

"entry" is zeroed when allocated.


  reply	other threads:[~2021-07-27 21:08 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-27 16:33 [PATCH v4 0/5] IMA: restrict the accepted digest algorithms for THOBY Simon
2021-07-27 16:33 ` [PATCH v4 1/5] IMA: remove the dependency on CRYPTO_MD5 THOBY Simon
2021-07-27 17:57   ` Mimi Zohar
2021-07-27 16:33 ` [PATCH v4 2/5] IMA: block writes of the security.ima xattr with unsupported algorithms THOBY Simon
2021-07-27 20:32   ` Mimi Zohar
2021-07-28  7:00     ` THOBY Simon
2021-07-28 12:43       ` Mimi Zohar
2021-07-28 12:53         ` THOBY Simon
2021-07-28 13:09           ` Mimi Zohar
2021-07-27 16:33 ` [PATCH v4 3/5] IMA: add support to restrict the hash algorithms used for file appraisal THOBY Simon
2021-07-27 20:38   ` Mimi Zohar
2021-07-27 16:33 ` [PATCH v4 4/5] IMA: add a policy option to restrict xattr hash algorithms on appraisal THOBY Simon
2021-07-27 21:07   ` Mimi Zohar [this message]
2021-07-27 16:33 ` [PATCH v4 5/5] IMA: introduce a new policy option func=SETXATTR_CHECK THOBY Simon
2021-07-27 17:25   ` Mimi Zohar
2021-07-27 17:58     ` THOBY Simon
2021-07-27 17:47 ` [PATCH v4 0/5] IMA: restrict the accepted digest algorithms for Mimi Zohar

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