From: Mimi Zohar <zohar@linux.ibm.com> To: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>, dhowells@redhat.com, matthewgarrett@google.com, sashal@kernel.org, jamorris@linux.microsoft.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 01/10] IMA: Defined an IMA hook to measure keys on key create or update Date: Thu, 07 Nov 2019 15:53:08 -0500 Message-ID: <1573159988.5028.400.camel@linux.ibm.com> (raw) In-Reply-To: <7ce84aa0-729e-c58e-f16a-25490b4e336d@linux.microsoft.com> On Thu, 2019-11-07 at 10:42 -0800, Lakshmi Ramasubramanian wrote: > On 11/6/2019 7:40 PM, Mimi Zohar wrote: > > >>> I would move the patch that defines the "keyring=" policy option prior > >>> to this one. Include the call to process_buffer_measurement() in this > >>> patch. A subsequent patch would add support to defer measuring the > >>> key, by calling a function named something like > >>> ima_queue_key_measurement(). > >>> > >> > >> As I'd stated in the other response, I wanted to isolate all key related > >> code in a separate C file and build it if and only if all CONFIG > >> dependencies are met. > > > > The basic measuring of keys shouldn't be any different than any other > > policy rule, other than it is a key and not a file. This is the > > reason that I keep saying start out with the basics and then add > > support to defer measuring keys on the trusted keyrings. > > I'll make the changes, rearrange the patches and send an updated set. > > I do have a few questions since I am still not fully understanding the > requirements you are targeting. Appreciate if you could please clarify. > > As you already know, I am using the "public key" of the given asymmetric > key as the "buffer" to measure in process_buffer_measurement(). > > The measurement decision is not based on whether the keyring is a > trusted one or an untrusted one. As long as the IMA policy allows > (through the "keyrings=" option) the key will be measured. We should be able to measure all keys being loaded onto any keyring or onto a specific "keyring=". This shouldn't be any different than any other policy rule. Once you have this basic feature working, you would address loading keys during early boot. > > Do you want only trusted keyrings to be allowed in the measurement? > In my opinion, that decision should be deferred to whoever is setting up > the IMA policy. Right, but it shouldn't be limited to just "trusted" keyrings. This way you can first test loading keys onto any keyring. > > > Only the queueing code needed for measuring keys on the trusted > > keyrings would be in a separate file. > > > > The decision to process key immediately or defer (queue) is based on > whether IMA has been initialized or not. Keyring is not used for this > decision. > > Could you please clarify how queuing is related to keyring's > trustworthiness? > > The check for whether the key is an asymmetric one or not, and > extracting the "public key" if it is an asymmetric key needs to be in a > separate file to handle the CONFIG dependencies in IMA. Queuing the keys should be independent of measuring the keys. Initially you would start with just measuring the key. From a high level it would look like: ima_post_key_create_or_update(...) { "measure key based on policy(key, keyring, ...)" } This requires the IMA "keyring=" policy option support be defined first. Subsequently you would add key queuing support, and then update ima_post_key_create_or_update(). It would look like: ima_post_key_create_or_update(...) { if (custom policy is loaded) "measure key based on policy(key, keyring, ...)" else "queue key(key, keyring)" } Mimi
next prev parent reply index Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-06 19:01 [PATCH v4 0/10] KEYS: Measure keys when they are created or updated Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 01/10] IMA: Defined an IMA hook to measure keys on key create or update Lakshmi Ramasubramanian 2019-11-06 22:43 ` Mimi Zohar 2019-11-07 0:21 ` Lakshmi Ramasubramanian 2019-11-07 3:40 ` Mimi Zohar 2019-11-07 18:42 ` Lakshmi Ramasubramanian 2019-11-07 20:53 ` Mimi Zohar [this message] 2019-11-07 21:12 ` Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 02/10] IMA: Added KEYRING_CHECK func in IMA policy to measure keys Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 03/10] IMA: Added keyrings= option in IMA policy to only measure keys added to the specified keyrings Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 04/10] IMA: Read keyrings= option from the IMA policy into ima_rule_entry Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 05/10] IMA: Updated IMA policy functions to return keyrings option read from the policy Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 06/10] IMA: Measure key if the IMA policy allows measurement for the keyring to which the key is linked to Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 07/10] IMA: Added a boolean flag to track IMA initialization status Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 08/10] IMA: Defined functions to queue and dequeue keys for measurement Lakshmi Ramasubramanian 2019-11-06 22:44 ` Mimi Zohar 2019-11-06 23:52 ` Lakshmi Ramasubramanian 2019-11-07 2:20 ` Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 09/10] IMA: Call queue and dequeue functions to measure keys Lakshmi Ramasubramanian 2019-11-06 19:01 ` [PATCH v4 10/10] KEYS: Call the IMA hook to measure key when a new key is created or an existing key is updated Lakshmi Ramasubramanian
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