linux/Documentation/filesystems
Eric Biggers 8094c3ceb2 fscrypt: add Adiantum support
Add support for the Adiantum encryption mode to fscrypt.  Adiantum is a
tweakable, length-preserving encryption mode with security provably
reducible to that of XChaCha12 and AES-256, subject to a security bound.
It's also a true wide-block mode, unlike XTS.  See the paper
"Adiantum: length-preserving encryption for entry-level processors"
(https://eprint.iacr.org/2018/720.pdf) for more details.  Also see
commit 059c2a4d8e ("crypto: adiantum - add Adiantum support").

On sufficiently long messages, Adiantum's bottlenecks are XChaCha12 and
the NH hash function.  These algorithms are fast even on processors
without dedicated crypto instructions.  Adiantum makes it feasible to
enable storage encryption on low-end mobile devices that lack AES
instructions; currently such devices are unencrypted.  On ARM Cortex-A7,
on 4096-byte messages Adiantum encryption is about 4 times faster than
AES-256-XTS encryption; decryption is about 5 times faster.

In fscrypt, Adiantum is suitable for encrypting both file contents and
names.  With filenames, it fixes a known weakness: when two filenames in
a directory share a common prefix of >= 16 bytes, with CTS-CBC their
encrypted filenames share a common prefix too, leaking information.
Adiantum does not have this problem.

Since Adiantum also accepts long tweaks (IVs), it's also safe to use the
master key directly for Adiantum encryption rather than deriving
per-file keys, provided that the per-file nonce is included in the IVs
and the master key isn't used for any other encryption mode.  This
configuration saves memory and improves performance.  A new fscrypt
policy flag is added to allow users to opt-in to this configuration.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-01-06 08:36:21 -05:00
..
caching fscache: Pass object size in rather than calling back for it 2018-04-06 14:05:14 +01:00
cifs smb3: update readme to correct information about /proc/fs/cifs/Stats 2018-08-07 14:20:23 -05:00
configfs fs: configfs: don't return anything from drop_link 2016-12-01 10:50:49 +01:00
ext4 docs: promote the ext4 data structures book to top level 2018-10-05 19:20:08 -04:00
nfs Olga added support for the NFSv4.2 asynchronous copy protocol. We 2018-10-30 13:03:29 -07:00
9p.txt
adfs.txt
affs.txt
afs.txt afs: Implement @sys substitution handling 2018-04-09 21:12:31 +01:00
autofs-mount-control.txt autofs: use autofs instead of autofs4 in documentation 2018-06-07 17:34:39 -07:00
autofs.txt autofs: use autofs instead of autofs4 in documentation 2018-06-07 17:34:39 -07:00
automount-support.txt autofs: use autofs instead of autofs4 in documentation 2018-06-07 17:34:39 -07:00
befs.txt
bfs.txt Tigran has moved 2017-05-12 15:57:15 -07:00
btrfs.txt Documentation: btrfs: remove usage specific information 2016-03-11 17:02:09 +01:00
ceph.txt ceph: new mount option to disable usage of copy-from op 2018-10-22 10:28:24 +02:00
coda.txt
conf.py docs-rst: convert filesystems book to ReST 2017-05-16 08:44:08 -03:00
cramfs.txt cramfs: rehabilitate it 2017-10-15 00:47:23 -04:00
dax.txt docs: fix some broken documentation references 2018-09-20 11:09:53 -06:00
debugfs.txt
devpts.txt devpts: Make each mount of devpts an independent filesystem. 2016-06-05 10:36:01 -07:00
directory-locking vfs: remove unused i_op->rename 2016-09-27 11:03:58 +02:00
dlmfs.txt
dnotify.txt Documentation: fix selftests related file refs 2017-10-19 12:58:21 -06:00
ecryptfs.txt
efivarfs.txt
exofs.txt
ext2.txt docs: fix some broken documentation references 2018-09-20 11:09:53 -06:00
ext3.txt
f2fs.txt f2fs: checkpoint disabling 2018-10-16 09:36:39 -07:00
fiemap.txt
files.txt
fscrypt.rst fscrypt: add Adiantum support 2019-01-06 08:36:21 -05:00
fuse-io.txt fuse: add writeback documentation 2018-03-20 17:11:45 +01:00
fuse.txt
gfs2-glocks.txt GFS2: Minor improvements to comments and documentation 2018-04-12 10:07:51 -07:00
gfs2-uevents.txt
gfs2.txt
hfs.txt
hfsplus.txt
hpfs.txt
index.rst docs: create filesystem internal section 2018-07-29 16:14:02 -04:00
inotify.txt
isofs.txt
jfs.txt
Locking overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
locks.txt docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
mandatory-locking.txt
nilfs2.txt MAINTAINERS, nilfs2: change project home URLs 2018-01-13 10:42:48 -08:00
ntfs.txt
ocfs2-online-filecheck.txt Doc: ocfs: Fix typo in filesystems/ocfs2-online-filecheck.txt 2016-07-01 16:17:15 -06:00
ocfs2.txt
omfs.txt
orangefs.txt Orangefs: documentation updates 2018-04-04 14:05:48 -04:00
overlayfs.txt ovl: automatically enable redirect_dir on metacopy=on 2018-11-01 21:31:39 +01:00
path-lookup.md autofs: use autofs instead of autofs4 in documentation 2018-06-07 17:34:39 -07:00
path-lookup.txt
porting vfs: rework data cloning infrastructure 2018-11-02 09:33:08 -07:00
proc.txt mm, proc: add KReclaimable to /proc/meminfo 2018-10-26 16:26:32 -07:00
qnx6.txt Documentation: fix common spelling mistakes 2016-04-28 07:51:59 -06:00
quota.txt scripts/spelling.txt: add "an user" pattern and fix typo instances 2017-02-27 18:43:46 -08:00
ramfs-rootfs-initramfs.txt initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
relay.txt Documentation : Update relay function types 2018-07-10 15:11:00 -06:00
romfs.txt
seq_file.txt fs/seq_file.c: simplify seq_file iteration code and interface 2018-08-17 16:20:28 -07:00
sharedsubtree.txt doc: fix grammar 2016-03-09 15:33:06 -07:00
spufs.txt
squashfs.txt
sysfs-pci.txt PCI: Add pci_mmap_resource_range() and use it for ARM64 2017-04-20 08:47:47 -05:00
sysfs-tagging.txt
sysfs.txt kallsyms: remove print_symbol() function 2018-01-16 16:59:55 +01:00
sysv-fs.txt
tmpfs.txt docs/vm: move numa_memory_policy.rst to Documentation/admin-guide/mm 2018-05-08 09:31:31 -06:00
ubifs-authentication.md Documentation: ubifs: Add authentication whitepaper 2018-10-23 13:49:01 +02:00
ubifs.txt ubifs: Enable authentication support 2018-10-23 13:49:01 +02:00
udf.txt udf: Remove never implemented mount options 2018-02-27 10:25:33 +01:00
ufs.txt
vfat.txt Documentation/filesystems/vfat.txt: fix a remark that implies UCS2 2017-12-21 13:39:28 -07:00
vfs.txt vfs: enable remap callers that can handle short operations 2018-10-30 10:42:10 +11:00
xfs-delayed-logging-design.txt
xfs-self-describing-metadata.txt
xfs.txt xfs: remove deprecated barrier/nobarrier mount 2018-07-26 10:15:17 -07:00