From: Tushar Sugandhi <firstname.lastname@example.org> To: Thore Sommer <email@example.com> Cc: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com Subject: Re: [dm-devel] [PATCH 0/7] device mapper target measurements using IMA Date: Thu, 29 Jul 2021 12:24:18 -0700 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> Hi Thore, Replying to a few questions which were not already answered by me/Alasdair. On 7/27/21 3:18 AM, Thore Sommer wrote: > There is no way to verify if the root hash was verified against a signature. We > have "root_hash_sig_key_desc SIGNATURE_DESCRIPTION" in the dm table. > "SIGNATURE_DESCRIPTION" itself is not really useful because it seems that we > cannot map it back to the certificate that was used for verification but the > presence of "root_hash_sig_key_desc" might be enough in combination with > measuring the keyring. Thanks for the suggestion Thore. I can update the verity_status() to measure if v->signature_key_desc is set. Something like: DMEMIT("signature_key_desc_present=%c,", v->signature_key_desc ? 'y' : 'n'); Alasdair, Mike, Can you tell if this is needed and/or sufficient? If it is needed, should we log the full string v->signature_key_desc? I am concerned about logging the full string as it is an unbounded buffer (a char*) coming from UM. And at the same time, not sure if just logging the presence is sufficient. Thoughts? Thore, Please note – even if we measure signature_key_desc (full string or just its presence): in order to use it with the keyrings, the IMA policy also needs to be set to measure key rings (using “measure func=KEY_CHECK ...”). It is independent from measuring the device mapper data (which is measured when the policy is set to “measure func=CRITICAL_DATA label=device-mapper ...”). Therefore measuring keyrings together (i.e. in the same IMA log) with DM data is not always guaranteed, since it is dictated by how the IMA policy is configured. Just FYI. > For remote attestation services it would be nice if we have clear indicator from > what component the "ima-buf" entry was generated. Prefixing all "n-ng" field > entries with something like "dm_" would make it easier for us to add different > validators for different measurements that use the "ima-buf" template. The > keyring measurements already use "ima-buf" and using some kind of naming scheme > to easily differentiate the entries would be nice. The event names typically come from kernel components that are doing the measurement of critical data. So any duplicates should be caught in the upstream review of the kernel patch. But thanks for the suggestion. I will prefix the event names in this patch series with “dm_” to indicate they are related to device mapper. Thanks, Tushar > Regards, > Thore >
next prev parent reply other threads:[~2021-07-29 19:24 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-13 0:48 Tushar Sugandhi 2021-07-13 0:48 ` [PATCH 1/7] dm: measure data on table load Tushar Sugandhi 2021-07-21 2:12 ` Mimi Zohar 2021-07-21 15:42 ` Mike Snitzer 2021-07-21 16:07 ` Mimi Zohar 2021-07-21 21:17 ` Mimi Zohar 2021-07-29 19:58 ` Tushar Sugandhi 2021-07-13 0:48 ` [PATCH 2/7] dm: measure data on device resume Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 3/7] dm: measure data on device remove Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 4/7] dm: measure data on table clear Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 5/7] dm: measure data on device rename Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 6/7] dm: update target specific status functions to measure data Tushar Sugandhi 2021-07-13 1:06 ` Alasdair G Kergon 2021-07-14 20:23 ` Tushar Sugandhi 2021-07-13 0:49 ` [PATCH 7/7] dm: add documentation for IMA measurement support Tushar Sugandhi 2021-07-21 2:33 ` Mimi Zohar 2021-07-24 7:25 ` Tushar Sugandhi 2021-07-26 16:33 ` Mimi Zohar 2021-07-26 18:28 ` Tushar Sugandhi 2021-07-14 11:32 ` [dm-devel] [PATCH 0/7] device mapper target measurements using IMA Thore Sommer 2021-07-14 20:20 ` Tushar Sugandhi 2021-07-27 10:18 ` Thore Sommer 2021-07-27 20:33 ` Alasdair G Kergon 2021-07-28 3:10 ` Tushar Sugandhi 2021-07-28 17:14 ` Thore Sommer 2021-07-29 17:32 ` Tushar Sugandhi 2021-07-28 17:34 ` Thore Sommer 2021-07-28 21:33 ` Alasdair G Kergon 2021-08-02 10:45 ` Thore Sommer 2021-07-29 19:24 ` Tushar Sugandhi [this message] 2021-08-02 10:38 ` Thore Sommer 2021-07-20 21:27 ` Mike Snitzer
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