Messages in this thread | | | Date | Thu, 29 Feb 2024 11:59:39 -0800 | Subject | Re: [RFC PATCH v13 17/20] ipe: enable support for fs-verity as a trust provider | From | Fan Wu <> |
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On 2/29/2024 11:42 AM, Eric Biggers wrote: > On Thu, Feb 29, 2024 at 10:59:21AM -0800, Fan Wu wrote: >>> >>> So IPE is interested in whether a file has an fsverity builtin signature, but it >>> doesn't care what the signature is or whether it has been checked. What is the >>> point? >>> >>> - Eric >> >> It does make sure the signature is checked. This hook call can only be >> triggered after fsverity_verify_signature() succeed. Therefore, for files >> that are marked with the security blob inode_sec->fs_verity_sign as true, >> they must successfully pass the fsverity_verify_signature() check. >> >> Regarding the other question, the current version does not support defining >> policies to trust files based on the inner content of their signatures >> because the current patch set is already too large. >> >> We plan to introduce new policy grammars to enable the policy to define >> which certificate of the signature can be trusted after this version is >> accepted. > > Ah, I see, you're relying on the fact that fsverity_verify_signature() verifies > the signature (if present) even if fs.verity.require_signatures hasn't been set. > That does happen to be its behavior, but this isn't clearly documented since > there previously wasn't really a use case for the builtin signatures without > setting fs.verity.require_signatures. Can you please make sure this behavior is > documented properly in Documentation/filesystems/fsverity.rst and in function > comments? Otherwise I worry that it could get changed and break your code. > > - Eric
Thanks for the suggestion. I will add this info in the next version. -Fan
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