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# SPDX-License-Identifier: GPL-2.0

config FS_VERITY
	bool "FS Verity (read-only file-based authenticity protection)"
	select CRYPTO
	# SHA-256 is selected as it's intended to be the default hash algorithm.
	# To avoid bloat, other wanted algorithms must be selected explicitly.
	select CRYPTO_SHA256
	help
	  This option enables fs-verity.  fs-verity is the dm-verity
	  mechanism implemented at the file level.  On supported
	  filesystems (currently EXT4 and F2FS), userspace can use an
	  ioctl to enable verity for a file, which causes the filesystem
	  to build a Merkle tree for the file.  The filesystem will then
	  transparently verify any data read from the file against the
	  Merkle tree.  The file is also made read-only.

	  This serves as an integrity check, but the availability of the
	  Merkle tree root hash also allows efficiently supporting
	  various use cases where normally the whole file would need to
	  be hashed at once, such as: (a) auditing (logging the file's
	  hash), or (b) authenticity verification (comparing the hash
	  against a known good value, e.g. from a digital signature).

	  fs-verity is especially useful on large files where not all
	  the contents may actually be needed.  Also, fs-verity verifies
	  data each time it is paged back in, which provides better
	  protection against malicious disks vs. an ahead-of-time hash.

	  If unsure, say N.

config FS_VERITY_DEBUG
	bool "FS Verity debugging"
	depends on FS_VERITY
	help
	  Enable debugging messages related to fs-verity by default.

	  Say N unless you are an fs-verity developer.