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2020-01-05Metadata support for v2 encryption policiesEric Biggers
Linux v5.4 and later supports v2 encryption policies. These have several advantages over v1 encryption policies: - Their encryption keys can be added/removed to/from the filesystem by non-root users, thus gaining the benefits of the filesystem keyring while also retaining support for non-root use. - They use a more standard, secure, and flexible key derivation function. Because of this, some future kernel-level fscrypt features will be implemented for v2 policies only. - They prevent a denial-of-service attack where a user could associate the wrong key with another user's encrypted files. Prepare the fscrypt tool to support v2 encryption policies by: - Adding a policy_version field to the EncryptionOptions, i.e. to the config file and to the policy metadata files. - Using the kernel-specified algorithm to compute the key descriptor for v2 policies. - Handling setting and getting v2 policies. Actually adding/removing the keys for v2 policies to/from the kernel is left for the next patch.
2017-06-28Finalize import paths and documentationv0.1.00.1.0Joe Richey joerichey@google.com
This commit changes all the internal import paths from `fscrypt/foo` to `github.com/google/fscrypt/foo` so that it can be built once we release externaly. The documentation in README.md is updated accordingly. Also, the README has a note noting that we do not make any guarantees about project stability before 1.0 (when it ships with Ubuntu). Change-Id: I6ba86e442c74057c8a06ba32a42e17f94833e280
2017-06-28Change error handling to new packageJoe Richey joerichey@google.com
This commit changes the error handing for the crypto, filesystem, metadata, pam, and util packages to use the error handling library github.com/pkg/errors. This means elimination of the FSError type, an increased use of wrapping errors (as opposed to logging), switching on the Cause() of an error (as opposed to its value), and improving our integration tests involving TEST_FILESYSTEM_ROOT. This commit also fixes a few bugs with the keyring code to ensure that our {Find|Remove|Insert}PolicyKey functions are always operating on the same keyring. The check for filesystem support has been moved from the filesystem package to the metadata package. Finally, the API for the filesystem package has been slightly modified: * filesystem.AllFilesystems() now returns all the filesystems in sorted order * certain path methods are now public O_SYNC is also removed for writing the metadata. We don't get that much from syncing the metadata, as the actual file data could also be corrupted by and IO error. The sync operation is also occasionally very slow (~3 seconds) and can be unfriendly to battery life. Change-Id: I392c2655141714b16dfdbc84ac09780072be2cf0
2017-05-31metadata: reorganize and add consistency checksJoe Richey joerichey@google.com
This commit adds in IsValid() checks for the metadata structures that let us enforce stronger invariants than those imposed by the protobuf package. The main uses of this will be to check that metadata is valid before writing it to the filesystem, and to check that the filesystem contains valid metadata before returning it to the user. These functions also will log the exact reason if the validity checks fail. To have these checks in the metadata package, all of the various constants have been moved to a single metadata/constants.go file. The uses of these constants were changed accordingly. Finally, this commit standardizes our use of errors so that they always begin with an appropriate prefix. Change-Id: I99008e2ee803ebe5f6236eb8d83fc83efcd22718