Re: [PATCH v4 14/16] ext4: add basic fs-verity support
From: "Theodore Ts'o" <tytso@mit.edu>
Date: 2019-06-15 15:31:37
Also in:
linux-ext4, linux-f2fs-devel, linux-fscrypt, linux-fsdevel, linux-integrity
On Thu, Jun 06, 2019 at 08:52:03AM -0700, Eric Biggers wrote:
quoted hunk ↗ jump to hunk
+/* + * Format of ext4 verity xattr. This points to the location of the verity + * descriptor within the file data rather than containing it directly because + * the verity descriptor *must* be encrypted when ext4 encryption is used. But, + * ext4 encryption does not encrypt xattrs. + */ +struct fsverity_descriptor_location { + __le32 version; + __le32 size; + __le64 pos; +};
What's the benefit of storing the location in an xattr as opposed to just keying it off the end of i_size, rounded up to next page size (or 64k) as I had suggested earlier? Using an xattr burns xattr space, which is a limited resource, and it adds some additional code complexity. Does the benefits outweigh the added complexity? - Ted