On Mon, Jul 01, 2019 at 08:32:34AM -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > Add most of fs-verity support to ext4. fs-verity is a filesystem > feature that enables transparent integrity protection and authentication > of read-only files. It uses a dm-verity like mechanism at the file > level: a Merkle tree is used to verify any block in the file in > log(filesize) time. It is implemented mainly by helper functions in > fs/verity/. See Documentation/filesystems/fsverity.rst for the full > documentation. > > This commit adds all of ext4 fs-verity support except for the actual > data verification, including: > > - Adding a filesystem feature flag and an inode flag for fs-verity. > > - Implementing the fsverity_operations to support enabling verity on an > inode and reading/writing the verity metadata. > > - Updating ->write_begin(), ->write_end(), and ->writepages() to support > writing verity metadata pages. > > - Calling the fs-verity hooks for ->open(), ->setattr(), and ->ioctl(). > > ext4 stores the verity metadata (Merkle tree and fsverity_descriptor) > past the end of the file, starting at the first 64K boundary beyond > i_size. This approach works because (a) verity files are readonly, and > (b) pages fully beyond i_size aren't visible to userspace but can be > read/written internally by ext4 with only some relatively small changes > to ext4. This approach avoids having to depend on the EA_INODE feature > and on rearchitecturing ext4's xattr support to support paging > multi-gigabyte xattrs into memory, and to support encrypting xattrs. > Note that the verity metadata *must* be encrypted when the file is, > since it contains hashes of the plaintext data. > > This patch incorporates work by Theodore Ts'o and Chandan Rajendra. > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Looks good. You can add: Reviewed-by: Theodore Ts'o <tytso@xxxxxxx> Thanks, - Ted
