author: Eric Biggers <ebiggers@google.com> 2019-07-22 09:26:21 -0700
committer: Eric Biggers <ebiggers@google.com> 2019-07-28 16:59:16 -0700
commit: 671e67b47e9fffd12c8f69eda853a202cb5b3fc5
parent: fe9918d3b228b3e8c726849d1486933f46b9069e
Commit Summary:
Diffstat:
1 file changed, 32 insertions, 0 deletions
diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig
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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.