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
