From: Mimi Zohar <zohar@linux.ibm.com>
To: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
linux-integrity@vger.kernel.org
Cc: eric.snowberg@oracle.com, dhowells@redhat.com,
matthewgarrett@google.com, sashal@kernel.org,
jamorris@linux.microsoft.com, linux-kernel@vger.kernel.org,
keyrings@vger.kernel.org
Subject: Re: [PATCH v9 6/6] IMA: Read keyrings= option from the IMA policy
Date: Wed, 27 Nov 2019 14:32:54 -0500 [thread overview]
Message-ID: <1574883174.4793.318.camel@linux.ibm.com> (raw)
In-Reply-To: <20191127015654.3744-7-nramas@linux.microsoft.com>
On Tue, 2019-11-26 at 17:56 -0800, Lakshmi Ramasubramanian wrote:
> Read "keyrings=" option, if specified in the IMA policy, and store in
> the list of IMA rules when the configured IMA policy is read.
>
> This patch defines a new policy token enum namely Opt_keyrings
> and an option flag IMA_KEYRINGS for reading "keyrings=" option
> from the IMA policy.
>
> Updated ima_parse_rule() to parse "keyrings=" option in the policy.
> Updated ima_policy_show() to display "keyrings=" option.
>
> The following example illustrates how key measurement can be verified.
The example is really too colloquial/verbose. Please truncate it,
leaving just a sample "key" policy rule, with directions for verifying
the template data against the digest included in the measurement list.
>
> Sample IMA Policy entry to measure keys
> (Added in the file /etc/ima/ima-policy):
Remove the above.
Sample "key" measurement rule:
> measure func=KEY_CHECK keyrings=.ima|.evm template=ima-buf
>
> Build the kernel with this patch set applied and reboot to that kernel.
>
> Ensure the IMA policy is applied:
>
> root@nramas:/home/nramas# cat /sys/kernel/security/ima/policy
> measure func=KEY_CHECK keyrings=.ima|.evm template=ima-buf
>
> View the initial IMA measurement log:
>
> root@nramas:/home/nramas
> # cat /sys/kernel/security/ima/ascii_runtime_measurements
> 10 67ec... ima-ng sha1:b5466c508583f0e633df83aa58fc7c5b67ccf667 boot_aggregate
>
> Now, add a certificate (for example, x509_ima.der) to the .ima keyring
> using evmctl (IMA-EVM Utility)
>
> root@nramas:/home/nramas# keyctl show %:.ima
> Keyring
> 547515640 ---lswrv 0 0 keyring: .ima
>
> root@nramas:/home/nramas# evmctl import x509_ima.der 547515640
>
> root@nramas:/home/nramas# keyctl show %:.ima
> Keyring
> 547515640 ---lswrv 0 0 keyring: .ima
> 809678766 --als--v 0 0 \_ asymmetric: hostname: whoami signing key: 052dd247dc3c36...
>
> View the updated IMA measurement log:
>
> root@nramas:/home/nramas#
Remove everything up to here and simply say something like:
Display "key" measurement in the IMA measurement list:
> # cat /sys/kernel/security/ima/ascii_runtime_measurements
> 10 3adf... ima-buf
> sha256:27c915b8ddb9fae7214cf0a8a7043cc3eeeaa7539bcb136f8427067b5f6c3
> b7b .ima 308202863082...4aee
> root@nramas:/home/nramas#
Remove this string from all the commands.
>
> For this sample, SHA256 should be selected as the hash algorithm
> used by IMA.
>
> The following command verifies if the SHA256 hash generated from
> the payload in the IMA log entry (listed above) for the .ima key
> matches the SHA256 hash in the IMA log entry. The output of this
> command should match the SHA256 hash given in the IMA log entry
> (In this case, it should be
> 27c915b8ddb9fae7214cf0a8a7043cc3eeeaa7539bcb136f8427067b5f6c3b7b)
Previously you didn't use the hash value, but ".ima" to locate the
"key" measurement in the measurement list. In each of the commands
above, it might be clearer.
>
> root@nramas:/home/nramas
ditto
> # cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements
> | grep
> 27c915b8ddb9fae7214cf0a8a7043cc3eeeaa7539bcb136f8427067b5f6c3b7b |
> cut -d' ' -f 6 | xxd -r -p |tee ima-cert.der | sha256sum | cut -d' '
> -f 1
>
> The above command also creates a binary file namely ima-cert.der
> using the payload in the IMA log entry. This file should be a valid
> x509 certificate which can be verified using openssl as given below:
>
> root@nramas:/home/nramas
ditto
> # openssl x509 -in ima-cert.der -inform DER -text
>
> The above command should display the contents of the file ima-cert.der
> as an x509 certificate.
Either the comments should be above or below the commands, not both.
>
> The IMA policy used here allows measurement of keys added to
> ".ima" and ".evm" keyrings only. Add a key to any other keyring and
> verify that the key is not measured.
This comment would be included, if desired, when defining the policy
rule, not here.
Mimi
next prev parent reply other threads:[~2019-11-27 19:33 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 1:56 [PATCH v9 0/6] KEYS: Measure keys when they are created or updated Lakshmi Ramasubramanian
2019-11-27 1:56 ` [PATCH v9 1/6] IMA: Check IMA policy flag Lakshmi Ramasubramanian
2019-11-27 1:56 ` [PATCH v9 2/6] IMA: Add KEY_CHECK func to measure keys Lakshmi Ramasubramanian
2019-11-27 1:56 ` [PATCH v9 3/6] IMA: Define an IMA hook " Lakshmi Ramasubramanian
2019-11-27 1:56 ` [PATCH v9 4/6] KEYS: Call the " Lakshmi Ramasubramanian
2019-11-27 1:56 ` [PATCH v9 5/6] IMA: Add support to limit measuring keys Lakshmi Ramasubramanian
2019-11-27 18:52 ` Mimi Zohar
2019-11-28 0:44 ` Lakshmi Ramasubramanian
2019-12-02 18:18 ` Mimi Zohar
2019-12-03 12:25 ` Mimi Zohar
2019-12-03 16:13 ` Lakshmi Ramasubramanian
2019-12-03 16:47 ` Mimi Zohar
2019-12-03 19:45 ` Lakshmi Ramasubramanian
2019-12-03 20:06 ` Mimi Zohar
2019-12-03 23:37 ` Lakshmi Ramasubramanian
2019-12-04 11:16 ` Mimi Zohar
2019-12-04 22:43 ` Lakshmi Ramasubramanian
2019-12-04 23:25 ` Mat Martineau
2019-11-27 1:56 ` [PATCH v9 6/6] IMA: Read keyrings= option from the IMA policy Lakshmi Ramasubramanian
2019-11-27 19:32 ` Mimi Zohar [this message]
2019-11-27 22:05 ` Lakshmi Ramasubramanian
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