Add the fsverity_file_open() function, which prepares an fs-verity file
to be read from. If not already done, it loads the fs-verity descriptor
from the filesystem and sets up an fsverity_info structure for the inode
which describes the Merkle tree and contains the file measurement. It
also denies all attempts to open verity files for writing.
This commit also begins the include/linux/fsverity.h header, which
declares the interface between fs/verity/ and filesystems.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add the beginnings of the fs/verity/ support layer, including the
Kconfig option and various helper functions for hashing. To start, only
SHA-256 is supported, but other hash algorithms can easily be added.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
