On Thu, May 09, 2024 at 11:20:17PM -0700, Christoph Hellwig wrote: > FYI, I spent some time looking over the core verity and ext4 code, > and I can't find anything enforcing any kind of size limit. Of course > testing that is kinda hard without taking sparseness into account. > > Eric, should fsverity or the fs backend check for a max size instead > od trying to build the merkle tree and evnetually failing to write it > out? > > An interesting note I found in the ext4 code is: > > Note that the verity metadata *must* be encrypted when the file is, > since it contains hashes of the plaintext data. Refresh my memory of fscrypt -- does it encrypt directory names, xattr names, and xattr values too? Or does it only do that to file data? > While xfs doesn't currently support fscrypyt it would actually be very > useful feature, so we're locking us into encrypting attrs or at least > magic attr fork data if we do our own non-standard fsverity storage. > I'm getting less and less happy with not just doing the normal post > i_size storage. Yes, it's not pretty (so isn't the whole fsverity idea > of shoehorning the hashes into file systems not built for it), but it > avoid adding tons of code and beeing very different. And if we copy the ext4 method of putting the merkle data after eof and loading it into the pagecache, how much of the generic fs/verity cleanup patches do we really need? --D
