From: Tushar Sugandhi <tusharsu@linux.microsoft.com> To: Mimi Zohar <zohar@linux.ibm.com>, dm-devel@redhat.com, agk@redhat.com, snitzer@redhat.com Cc: linux-integrity@vger.kernel.org, nramas@linux.microsoft.com Subject: Re: [PATCH 7/7] dm: add documentation for IMA measurement support Date: Sat, 24 Jul 2021 00:25:54 -0700 [thread overview] Message-ID: <6b81b92f-7d7b-d198-5056-bab1bcbac522@linux.microsoft.com> (raw) In-Reply-To: <205b5336d60aee6b3f33ad67b2d0250e104d6779.camel@linux.ibm.com> Hi Mimi, On 7/20/21 7:33 PM, Mimi Zohar wrote: > Hi Tushar, Mike, > > On Mon, 2021-07-12 at 17:49 -0700, Tushar Sugandhi wrote: >> +Then IMA ASCII measurement log has the following format: >> +PCR TEMPLATE_DIGEST TEMPLATE ALG:EVENT_DIGEST EVENT_NAME EVENT_DATA >> + >> +PCR := Platform Configuration Register, in which the values are registered. >> + This is applicable if TPM chip is in use. >> +TEMPLATE_DIGEST := Template digest of the IMA record. > > ^TEMPLATE_DATA_DIGEST > Will do. >> +TEMPLATE := Template that registered the integrity value (e.g. ima-buf). > > ^TEMPLATE_NAME > Will do. > The template data format consists of: >> +ALG:EVENT_DIGEST = Algorithm to compute event digest, followed by digest of event data >> +EVENT_NAME := Description of the event (e.g. 'table_load'). >> +EVENT_DATA := The event data to be measured. > Thanks. I will add this to the dm-ima documentation. > Missing from the document is a way of validating the template data. > For example, in the original case of file measurements, the template > data contains the file hash, which can be recalculated or verified > against an allow list. > > Other than re-calculating the template data digest based on the > template data, and verifying it against the template data digest in the > measurement list, would an attestation server be able to verify the > template data itself? > Yes. In the context of device-mapper, EVENT_DATA for 'table_load' would contain the key-value pairs for various targets in the table (crypt, verity, integrity etc.) which the attestation servers should be able to verify against the allowed/expected key-value pairs specified in the attestation policy. To avoid bloating the IMA log with same data from table_load again, we only measure hash of the loaded table in the EVENT_DATA - when there is a state change for DM device. e.g. when EVENT_NAME is 'device_resume', 'table_clear', 'device_remove' etc. Since the table clear-text is already present in the EVENT_DATA buffer for 'table_load', and is available to attestation servers, verifying the corresponding hash values in the EVENT_DATA in the subsequent DM events should be possible for the attestation servers. Please let us know if you need further info. Thanks, Tushar > thanks, > > Mimi >
WARNING: multiple messages have this Message-ID (diff)
From: Tushar Sugandhi <tusharsu@linux.microsoft.com> To: Mimi Zohar <zohar@linux.ibm.com>, dm-devel@redhat.com, agk@redhat.com, snitzer@redhat.com Cc: nramas@linux.microsoft.com, linux-integrity@vger.kernel.org Subject: Re: [dm-devel] [PATCH 7/7] dm: add documentation for IMA measurement support Date: Sat, 24 Jul 2021 00:25:54 -0700 [thread overview] Message-ID: <6b81b92f-7d7b-d198-5056-bab1bcbac522@linux.microsoft.com> (raw) In-Reply-To: <205b5336d60aee6b3f33ad67b2d0250e104d6779.camel@linux.ibm.com> Hi Mimi, On 7/20/21 7:33 PM, Mimi Zohar wrote: > Hi Tushar, Mike, > > On Mon, 2021-07-12 at 17:49 -0700, Tushar Sugandhi wrote: >> +Then IMA ASCII measurement log has the following format: >> +PCR TEMPLATE_DIGEST TEMPLATE ALG:EVENT_DIGEST EVENT_NAME EVENT_DATA >> + >> +PCR := Platform Configuration Register, in which the values are registered. >> + This is applicable if TPM chip is in use. >> +TEMPLATE_DIGEST := Template digest of the IMA record. > > ^TEMPLATE_DATA_DIGEST > Will do. >> +TEMPLATE := Template that registered the integrity value (e.g. ima-buf). > > ^TEMPLATE_NAME > Will do. > The template data format consists of: >> +ALG:EVENT_DIGEST = Algorithm to compute event digest, followed by digest of event data >> +EVENT_NAME := Description of the event (e.g. 'table_load'). >> +EVENT_DATA := The event data to be measured. > Thanks. I will add this to the dm-ima documentation. > Missing from the document is a way of validating the template data. > For example, in the original case of file measurements, the template > data contains the file hash, which can be recalculated or verified > against an allow list. > > Other than re-calculating the template data digest based on the > template data, and verifying it against the template data digest in the > measurement list, would an attestation server be able to verify the > template data itself? > Yes. In the context of device-mapper, EVENT_DATA for 'table_load' would contain the key-value pairs for various targets in the table (crypt, verity, integrity etc.) which the attestation servers should be able to verify against the allowed/expected key-value pairs specified in the attestation policy. To avoid bloating the IMA log with same data from table_load again, we only measure hash of the loaded table in the EVENT_DATA - when there is a state change for DM device. e.g. when EVENT_NAME is 'device_resume', 'table_clear', 'device_remove' etc. Since the table clear-text is already present in the EVENT_DATA buffer for 'table_load', and is available to attestation servers, verifying the corresponding hash values in the EVENT_DATA in the subsequent DM events should be possible for the attestation servers. Please let us know if you need further info. Thanks, Tushar > thanks, > > Mimi > -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
next prev parent reply other threads:[~2021-07-24 7:25 UTC|newest] Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-13 0:48 [PATCH 0/7] device mapper target measurements using IMA Tushar Sugandhi 2021-07-13 0:48 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:48 ` [PATCH 1/7] dm: measure data on table load Tushar Sugandhi 2021-07-13 0:48 ` [dm-devel] " Tushar Sugandhi 2021-07-21 2:12 ` Mimi Zohar 2021-07-21 2:12 ` [dm-devel] " Mimi Zohar 2021-07-21 15:42 ` Mike Snitzer 2021-07-21 15:42 ` [dm-devel] " Mike Snitzer 2021-07-21 16:07 ` Mimi Zohar 2021-07-21 16:07 ` [dm-devel] " Mimi Zohar 2021-07-21 21:17 ` Mimi Zohar 2021-07-21 21:17 ` [dm-devel] " Mimi Zohar 2021-07-29 19:58 ` Tushar Sugandhi 2021-07-29 19:58 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:48 ` [PATCH 2/7] dm: measure data on device resume Tushar Sugandhi 2021-07-13 0:48 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 3/7] dm: measure data on device remove Tushar Sugandhi 2021-07-13 0:49 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 4/7] dm: measure data on table clear Tushar Sugandhi 2021-07-13 0:49 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 5/7] dm: measure data on device rename Tushar Sugandhi 2021-07-13 0:49 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 6/7] dm: update target specific status functions to measure data Tushar Sugandhi 2021-07-13 0:49 ` [dm-devel] " Tushar Sugandhi 2021-07-13 1:06 ` Alasdair G Kergon 2021-07-13 1:06 ` [dm-devel] " Alasdair G Kergon 2021-07-14 20:23 ` Tushar Sugandhi 2021-07-14 20:23 ` [dm-devel] " Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 7/7] dm: add documentation for IMA measurement support Tushar Sugandhi 2021-07-13 0:49 ` [dm-devel] " Tushar Sugandhi 2021-07-21 2:33 ` Mimi Zohar 2021-07-21 2:33 ` [dm-devel] " Mimi Zohar 2021-07-24 7:25 ` Tushar Sugandhi [this message] 2021-07-24 7:25 ` Tushar Sugandhi 2021-07-26 16:33 ` Mimi Zohar 2021-07-26 16:33 ` [dm-devel] " Mimi Zohar 2021-07-26 18:28 ` Tushar Sugandhi 2021-07-26 18:28 ` [dm-devel] " Tushar Sugandhi 2021-07-14 11:32 ` [dm-devel] [PATCH 0/7] device mapper target measurements using IMA Thore Sommer 2021-07-14 11:32 ` Thore Sommer 2021-07-14 20:20 ` Tushar Sugandhi 2021-07-14 20:20 ` Tushar Sugandhi 2021-07-27 10:18 ` Thore Sommer 2021-07-27 10:18 ` Thore Sommer 2021-07-27 20:33 ` Alasdair G Kergon 2021-07-27 20:33 ` Alasdair G Kergon 2021-07-28 3:10 ` Tushar Sugandhi 2021-07-28 3:10 ` Tushar Sugandhi 2021-07-28 17:14 ` Thore Sommer 2021-07-28 17:14 ` Thore Sommer 2021-07-29 17:32 ` Tushar Sugandhi 2021-07-29 17:32 ` Tushar Sugandhi 2021-07-28 17:34 ` Thore Sommer 2021-07-28 17:34 ` Thore Sommer 2021-07-28 21:33 ` Alasdair G Kergon 2021-07-28 21:33 ` Alasdair G Kergon 2021-08-02 10:45 ` Thore Sommer 2021-08-02 10:45 ` Thore Sommer 2021-07-29 19:24 ` Tushar Sugandhi 2021-07-29 19:24 ` Tushar Sugandhi 2021-08-02 10:38 ` Thore Sommer 2021-08-02 10:38 ` Thore Sommer 2021-07-20 21:27 ` Mike Snitzer 2021-07-20 21:27 ` [dm-devel] " Mike Snitzer 2021-07-24 6:57 ` Tushar Sugandhi
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=6b81b92f-7d7b-d198-5056-bab1bcbac522@linux.microsoft.com \ --to=tusharsu@linux.microsoft.com \ --cc=agk@redhat.com \ --cc=dm-devel@redhat.com \ --cc=linux-integrity@vger.kernel.org \ --cc=nramas@linux.microsoft.com \ --cc=snitzer@redhat.com \ --cc=zohar@linux.ibm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.