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authorLinus Torvalds <torvalds@linux-foundation.org>2019-03-09 21:54:24 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-09 21:54:24 +0300
commitd1cae94871330cb9f5fdcea34529abf7917e682e (patch)
tree727bdda6b15bc1252c61eff0d77395e8c02d56c1 /Documentation
parent99b25a7fc6150d613be8eab71a47e6c0fcc8d7c5 (diff)
parent129ca2d2a83f44551e73a408fa5e75a7b5169abb (diff)
downloadlinux-d1cae94871330cb9f5fdcea34529abf7917e682e.tar.xz
Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt
Pull fscrypt updates from Eric Biggers: "First: Ted, Jaegeuk, and I have decided to add me as a co-maintainer for fscrypt, and we're now using a shared git tree. So we've updated MAINTAINERS accordingly, and I'm doing the pull request this time. The actual changes for v5.1 are: - Remove the fs-specific kconfig options like CONFIG_EXT4_ENCRYPTION and make fscrypt support for all fscrypt-capable filesystems be controlled by CONFIG_FS_ENCRYPTION, similar to how CONFIG_QUOTA works. - Improve error code for rename() and link() into encrypted directories. - Various cleanups" * tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt: MAINTAINERS: add Eric Biggers as an fscrypt maintainer fscrypt: return -EXDEV for incompatible rename or link into encrypted dir fscrypt: remove filesystem specific build config option f2fs: use IS_ENCRYPTED() to check encryption status ext4: use IS_ENCRYPTED() to check encryption status fscrypt: remove CRYPTO_CTR dependency
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/fscrypt.rst16
1 files changed, 12 insertions, 4 deletions
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 3a7b60521b94..08c23b60e016 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -343,9 +343,9 @@ FS_IOC_SET_ENCRYPTION_POLICY can fail with the following errors:
- ``ENOTEMPTY``: the file is unencrypted and is a nonempty directory
- ``ENOTTY``: this type of filesystem does not implement encryption
- ``EOPNOTSUPP``: the kernel was not configured with encryption
- support for this filesystem, or the filesystem superblock has not
+ support for filesystems, or the filesystem superblock has not
had encryption enabled on it. (For example, to use encryption on an
- ext4 filesystem, CONFIG_EXT4_ENCRYPTION must be enabled in the
+ ext4 filesystem, CONFIG_FS_ENCRYPTION must be enabled in the
kernel config, and the superblock must have had the "encrypt"
feature flag enabled using ``tune2fs -O encrypt`` or ``mkfs.ext4 -O
encrypt``.)
@@ -451,10 +451,18 @@ astute users may notice some differences in behavior:
- Unencrypted files, or files encrypted with a different encryption
policy (i.e. different key, modes, or flags), cannot be renamed or
linked into an encrypted directory; see `Encryption policy
- enforcement`_. Attempts to do so will fail with EPERM. However,
+ enforcement`_. Attempts to do so will fail with EXDEV. However,
encrypted files can be renamed within an encrypted directory, or
into an unencrypted directory.
+ Note: "moving" an unencrypted file into an encrypted directory, e.g.
+ with the `mv` program, is implemented in userspace by a copy
+ followed by a delete. Be aware that the original unencrypted data
+ may remain recoverable from free space on the disk; prefer to keep
+ all files encrypted from the very beginning. The `shred` program
+ may be used to overwrite the source files but isn't guaranteed to be
+ effective on all filesystems and storage devices.
+
- Direct I/O is not supported on encrypted files. Attempts to use
direct I/O on such files will fall back to buffered I/O.
@@ -541,7 +549,7 @@ not be encrypted.
Except for those special files, it is forbidden to have unencrypted
files, or files encrypted with a different encryption policy, in an
encrypted directory tree. Attempts to link or rename such a file into
-an encrypted directory will fail with EPERM. This is also enforced
+an encrypted directory will fail with EXDEV. This is also enforced
during ->lookup() to provide limited protection against offline
attacks that try to disable or downgrade encryption in known locations
where applications may later write sensitive data. It is recommended