[v2,0/6] Support for Casefolding and Encryption

Message

Daniel Rosenberg Jan. 7, 2020, 5:16 a.m. UTC

Ext4 and F2FS currently both support casefolding and encryption, but not at
the same time. These patches aim to rectify that.

Since directory names are stored case preserved, we cannot just take the hash
of the ciphertext. Instead we use the siphash of the casefolded name. With this
we no longer have a direct path from an encrypted name to the hash without the
key. To deal with this, fscrypt now always includes the hash in the name it
presents when the key is not present. There is a pre-existing bug where you can
change parts of the hash and still match the name so long as the disruption to
the hash does not happen to affect lookup on that filesystem. I'm not sure how
to fix that without making ext4 lookups slower in the more common case.

I moved the identical dcache operations for ext4 and f2fs into the VFS, as any
filesystem that uses casefolding will need the same code. This will also allow
further optimizations to that path, although my current changes don't take
advantage of that yet.

For Ext4, this also means that we need to store the hash on disk. We only do so
for encrypted and casefolded directories to avoid on disk format changes.
Previously encryption and casefolding could not live on the same filesystem,
and we're relaxing that requirement. F2fs is a bit more straightforward since
it already stores hashes on disk.

I've updated the related tools with just enough to enable the feature. I still
need to adjust their respective fsck's, although without access to the keys,
they won't be able to verify the hashes of casefolded and encrypted names.

changes:
fscrypt moved to separate thread to rebase on fscrypt dev branch
addressed feedback, plus some minor fixes

Daniel Rosenberg (6):
  TMP: fscrypt: Add support for casefolding with encryption
  vfs: Fold casefolding into vfs
  f2fs: Handle casefolding with Encryption
  ext4: Use struct super_blocks' casefold data
  ext4: Hande casefolding with encryption
  ext4: Optimize match for casefolded encrypted dirs

 Documentation/filesystems/ext4/directory.rst |  27 ++
 fs/crypto/Kconfig                            |   1 +
 fs/crypto/fname.c                            | 234 ++++++++++---
 fs/crypto/fscrypt_private.h                  |   9 +
 fs/crypto/keysetup.c                         |  32 +-
 fs/crypto/policy.c                           |  45 ++-
 fs/dcache.c                                  |  28 ++
 fs/ext4/dir.c                                |  75 +----
 fs/ext4/ext4.h                               |  87 +++--
 fs/ext4/hash.c                               |  26 +-
 fs/ext4/ialloc.c                             |   5 +-
 fs/ext4/inline.c                             |  41 ++-
 fs/ext4/namei.c                              | 326 ++++++++++++-------
 fs/ext4/super.c                              |  21 +-
 fs/f2fs/dir.c                                | 114 +++----
 fs/f2fs/f2fs.h                               |  14 +-
 fs/f2fs/hash.c                               |  25 +-
 fs/f2fs/inline.c                             |   9 +-
 fs/f2fs/super.c                              |  17 +-
 fs/f2fs/sysfs.c                              |   8 +-
 fs/inode.c                                   |   7 +
 fs/namei.c                                   |  41 ++-
 include/linux/fs.h                           |  10 +
 include/linux/fscrypt.h                      |  96 ++----
 include/linux/unicode.h                      |  14 +
 25 files changed, 835 insertions(+), 477 deletions(-)

Comments

Theodore Ts'o Jan. 8, 2020, 6:50 p.m. UTC | #1

On Mon, Jan 06, 2020 at 09:16:32PM -0800, Daniel Rosenberg wrote:
> changes:
> fscrypt moved to separate thread to rebase on fscrypt dev branch
> addressed feedback, plus some minor fixes

What branch was this based on?  There is no fscrypt dev branch, so I
took the fscrypt master branch, and then applied your fscrypt patches,
and then I tried to apply this patch series.  I got patch conflicts
starting with the very first patch.

Applying: TMP: fscrypt: Add support for casefolding with encryption
error: patch failed: fs/crypto/Kconfig:9
error: fs/crypto/Kconfig: patch does not apply
error: patch failed: fs/crypto/fname.c:12
error: fs/crypto/fname.c: patch does not apply
error: patch failed: fs/crypto/fscrypt_private.h:12
error: fs/crypto/fscrypt_private.h: patch does not apply
error: patch failed: fs/crypto/keysetup.c:192
error: fs/crypto/keysetup.c: patch does not apply
error: patch failed: fs/crypto/policy.c:67
error: fs/crypto/policy.c: patch does not apply
error: patch failed: fs/inode.c:20
error: fs/inode.c: patch does not apply
error: patch failed: include/linux/fscrypt.h:127
error: include/linux/fscrypt.h: patch does not apply
Patch failed at 0001 TMP: fscrypt: Add support for casefolding with encryption
hint: Use 'git am --show-current-patch' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

   	       		       	   		  - Ted

Daniel Rosenberg Jan. 8, 2020, 9:24 p.m. UTC | #2

On Wed, Jan 8, 2020 at 10:50 AM Theodore Y. Ts'o <[e-mail]> wrote:
>
> On Mon, Jan 06, 2020 at 09:16:32PM -0800, Daniel Rosenberg wrote:
> > changes:
> > fscrypt moved to separate thread to rebase on fscrypt dev branch
> > addressed feedback, plus some minor fixes
>
> What branch was this based on?  There is no fscrypt dev branch, so I
> took the fscrypt master branch, and then applied your fscrypt patches,
> and then I tried to apply this patch series.  I got patch conflicts
> starting with the very first patch.
>
> Applying: TMP: fscrypt: Add support for casefolding with encryption
> error: patch failed: fs/crypto/Kconfig:9
> error: fs/crypto/Kconfig: patch does not apply
> error: patch failed: fs/crypto/fname.c:12
> error: fs/crypto/fname.c: patch does not apply
> error: patch failed: fs/crypto/fscrypt_private.h:12
> error: fs/crypto/fscrypt_private.h: patch does not apply
> error: patch failed: fs/crypto/keysetup.c:192
> error: fs/crypto/keysetup.c: patch does not apply
> error: patch failed: fs/crypto/policy.c:67
> error: fs/crypto/policy.c: patch does not apply
> error: patch failed: fs/inode.c:20
> error: fs/inode.c: patch does not apply
> error: patch failed: include/linux/fscrypt.h:127
> error: include/linux/fscrypt.h: patch does not apply
> Patch failed at 0001 TMP: fscrypt: Add support for casefolding with encryption
> hint: Use 'git am --show-current-patch' to see the failed patch
> When you have resolved this problem, run "git am --continue".
> If you prefer to skip this patch, run "git am --skip" instead.
> To restore the original branch and stop patching, run "git am --abort".
>
>                                                   - Ted
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to [e-mail].
>

This is based off of ToT master. I put in a dummy fscrypt patch so you
wouldn't need to rebase on top of fscrypt, but I could just do future
patch sets all on top of fscrypt-dev. I guess my attempt to make it
easier just made it more confusing :(