[RFC] Preliminary BTRFS Encryption

[Anand Jain <anand.jain@oracle.com>]

This patchset adds btrfs encryption support.

The main objective of this series is to have bugs fixed and stability.
I have verified with fstests to confirm that there is no regression.

A design write-up is coming next, however here below is the quick example
on the cli usage. Please try out, let me know if I have missed something.

Also would like to mention that a review from the security experts is due,
which is important and I believe those review comments can be accommodated
without major changes from here.

Also yes, thanks for the emails, I hear, per file encryption and inline
with vfs layer is also important, which is wip among other things in the
list.

As of now these patch set supports encryption on per subvolume, as
managing properties on per subvolume is a kind of core to btrfs, which is
easier for data center solution-ing, seamlessly persistent and easy to
manage.


Steps:
-----

Make sure following kernel TFMs are compiled in.
# cat /proc/crypto | egrep 'cbc\(aes\)|ctr\(aes\)'
name         : ctr(aes)
name         : cbc(aes)

Create encrypted subvolume.
# btrfs su create -e 'ctr(aes)' /btrfs/e1
Create subvolume '/btrfs/e1'
Passphrase: 
Again passphrase: 

A key is created and its hash is updated into the subvolume item,
and then added to the system keyctl.
# btrfs su show /btrfs/e1 | egrep -i encrypt
	Encryption: 		ctr(aes)@btrfs:75197c8e (594790215)

# keyctl show 594790215
Keyring
 594790215 --alsw-v      0     0  logon: btrfs:75197c8e


Now any file data extents under the subvol /btrfs/e1 will be
encrypted.

You may revoke key using keyctl or btrfs(8) as below.
# btrfs su encrypt -k out /btrfs/e1

# btrfs su show /btrfs/e1 | egrep -i encrypt
	Encryption: 		ctr(aes)@btrfs:75197c8e (Required key not available)

# keyctl show 594790215
Keyring
Unable to dump key: Key has been revoked

As the key hash is updated, If you provide wrong passphrase in the next
key in, it won't add key to the system. So we have key verification
from the day1.

# btrfs su encrypt -k in /btrfs/e1
Passphrase: 
Again passphrase: 
ERROR: failed to set attribute 'btrfs.encrypt' to 'ctr(aes)@btrfs:75197c8e' : Key was rejected by service

ERROR: key set failed: Key was rejected by service

# btrfs su encrypt -k in /btrfs/e1
Passphrase: 
Again passphrase: 
key for '/btrfs/e1' has  logged in with keytag 'btrfs:75197c8e'

Now if you revoke the key the read / write fails with key error.

# md5sum /btrfs/e1/2k-test-file 
8c9fbc69125ebe84569a5c1ca088cb14  /btrfs/e1/2k-test-file

# btrfs su encrypt -k out /btrfs/e1

# md5sum /btrfs/e1/2k-test-file 
md5sum: /btrfs/e1/2k-test-file: Key has been revoked

# cp /tfs/1k-test-file /btrfs/e1/
cp: cannot create regular file ‘/btrfs/e1/1k-test-file’: Key has been revoked

Plain text memory scratches for security reason is pending. As there are some
key revoke notification challenges to coincide with encryption context switch,
which I do believe should be fixed in the due course, but is not a roadblock
at this stage.

Thanks, Anand


Anand Jain (1):
  btrfs: Encryption: Add btrfs encryption support

 fs/btrfs/Makefile               |   4 +-
 fs/btrfs/btrfs_inode.h          |   6 +
 fs/btrfs/compression.c          |  30 +-
 fs/btrfs/compression.h          |  10 +-
 fs/btrfs/ctree.h                |   4 +
 fs/btrfs/disk-io.c              |   3 +
 fs/btrfs/encrypt.c              | 807 ++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/encrypt.h              |  94 +++++
 fs/btrfs/inode.c                | 255 ++++++++++++-
 fs/btrfs/ioctl.c                |  67 ++++
 fs/btrfs/lzo.c                  |   2 +-
 fs/btrfs/props.c                | 331 +++++++++++++++-
 fs/btrfs/super.c                |  27 +-
 fs/btrfs/tests/crypto-tests.c   | 376 +++++++++++++++++++
 fs/btrfs/tests/crypto-tests.h   |  38 ++
 fs/btrfs/zlib.c                 |   2 +-
 include/uapi/linux/btrfs_tree.h |   6 +-
 17 files changed, 2027 insertions(+), 35 deletions(-)
 create mode 100644 fs/btrfs/encrypt.c
 create mode 100644 fs/btrfs/encrypt.h
 create mode 100755 fs/btrfs/tests/crypto-tests.c
 create mode 100755 fs/btrfs/tests/crypto-tests.h

Anand Jain (2):
  btrfs-progs: make wait_for_commit non static
  btrfs-progs: add encryption support

 Makefile.in       |   5 +-
 btrfs-list.c      |  33 ++++
 cmds-filesystem.c |   4 +-
 cmds-restore.c    |  16 ++
 cmds-subvolume.c  | 112 ++++++++++++--
 commands.h        |   1 +
 ctree.h           |   5 +-
 encrypt.c         | 455 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 encrypt.h         |  46 ++++++
 props.c           |   4 +
 utils.h           |   2 +
 11 files changed, 665 insertions(+), 18 deletions(-)
 create mode 100644 encrypt.c
 create mode 100644 encrypt.h

Anand Jain (1):
  fstests: btrfs: support encryption

 common/filter.btrfs |   2 +-
 common/rc           |   2 +-
 tests/btrfs/041     |   2 +
 tests/btrfs/041.out |  13 ++++
 tests/btrfs/052     |  12 +++
 tests/btrfs/052.out | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/079     |   2 +
 tests/btrfs/125     |   2 +-
 tests/generic/297   |   6 +-
 tests/generic/298   |   2 +-
 10 files changed, 251 insertions(+), 6 deletions(-)