Messages in this thread |  | | Date | Thu, 27 Jun 2019 18:52:02 -0700 (PDT) | From | Jaskaran Singh Khurana <> | Subject | Re: [RFC PATCH v5 1/1] Add dm verity root hash pkcs7 sig validation. |
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On Thu, 27 Jun 2019, Milan Broz wrote:
> Hi, > > I tried to test test the patch, two comments below. > > On 19/06/2019 21:10, Jaskaran Khurana wrote: >> The verification is to support cases where the roothash is not secured by >> Trusted Boot, UEFI Secureboot or similar technologies. >> One of the use cases for this is for dm-verity volumes mounted after boot, >> the root hash provided during the creation of the dm-verity volume has to >> be secure and thus in-kernel validation implemented here will be used >> before we trust the root hash and allow the block device to be created. >> >> The signature being provided for verification must verify the root hash and >> must be trusted by the builtin keyring for verification to succeed. >> >> The hash is added as a key of type "user" and the description is passed to >> the kernel so it can look it up and use it for verification. >> >> Kernel commandline parameter will indicate whether to check (only if >> specified) or force (for all dm verity volumes) roothash signature >> verification. >> >> Kernel commandline: dm_verity.verify_sig=1 or 2 for check/force root hash >> signature validation respectively. > > 1) I think the switch should be just boolean - enforce signatures for all dm-verity targets > (with default to false/off). > > The rest should be handled by simple logic - if the root_hash_sig_key_desc option > is specified, the signature MUST be validated in the constructor, all errors should cause > failure (bad reference in keyring, bad signature, etc). > > (Now it ignores for example bad reference to the keyring, this is quite misleading.) > > If a user wants to activate a dm-verity device without a signature, just remove > optional argument referencing the signature. > (This is not possible with dm_verity.verify_sig set to true/on.) > > > 2) All DM targets must provide the same mapping table status ("dmsetup table" > command) as initially configured. > The output of the command should be directly usable as mapping table constructor. > > Your patch is missing that part, I tried to fix it, add-on patch is here > https://git.kernel.org/pub/scm/linux/kernel/git/mbroz/linux.git/commit/?h=dm-cryptsetup&id=a26c10806f5257e255b6a436713127e762935ad3 > (feel free to fold it in your patch) > > > Thanks, > Milan > Hello Milan,
Thanks for testing and reviewing this. I will take care of the above comments change it to a boolean and for the second point merge the add-on patch that you shared.
Regards, Jaskaran
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