| # 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. | |
| config FS_VERITY_BUILTIN_SIGNATURES | |
| bool "FS Verity builtin signature support" | |
| depends on FS_VERITY | |
| select SYSTEM_DATA_VERIFICATION | |
| help | |
| Support verifying signatures of verity files against the X.509 | |
| certificates that have been loaded into the ".fs-verity" | |
| kernel keyring. | |
| This is meant as a relatively simple mechanism that can be | |
| used to provide an authenticity guarantee for verity files, as | |
| an alternative to IMA appraisal. Userspace programs still | |
| need to check that the verity bit is set in order to get an | |
| authenticity guarantee. | |
| If unsure, say N. |