[PATCH v2 0/9] Allow deleting files with unsupported encryption policy

[Eric Biggers]

On Wed, Dec 02, 2020 at 06:20:32PM -0800, Eric Biggers wrote:
> Currently it's impossible to delete files that use an unsupported
> encryption policy, as the kernel will just return an error when
> performing any operation on the top-level encrypted directory, even just
> a path lookup into the directory or opening the directory for readdir.
> 
> It's desirable to return errors for most operations on files that use an
> unsupported encryption policy, but the current behavior is too strict.
> We need to allow enough to delete files, so that people can't be stuck
> with undeletable files when downgrading kernel versions.  That includes
> allowing directories to be listed and allowing dentries to be looked up.
> 
> This series fixes this (on ext4, f2fs, and ubifs) by treating an
> unsupported encryption policy in the same way as "key unavailable" in
> the cases that are required for a recursive delete to work.
> 
> The actual fix is in patch 9, so see that for more details.
> 
> Patches 1-8 are cleanups that prepare for the actual fix by removing
> direct use of fscrypt_get_encryption_info() by filesystems.
> 
> This patchset applies to branch "master" (commit 4a4b8721f1a5) of
> https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git.
> 
> Changed since v1:
>   - Made some minor updates to commit messages.
>   - Added Reviewed-by tags.
> 
> Eric Biggers (9):
>   ext4: remove ext4_dir_open()
>   f2fs: remove f2fs_dir_open()
>   ubifs: remove ubifs_dir_open()
>   ext4: don't call fscrypt_get_encryption_info() from dx_show_leaf()
>   fscrypt: introduce fscrypt_prepare_readdir()
>   fscrypt: move body of fscrypt_prepare_setattr() out-of-line
>   fscrypt: move fscrypt_require_key() to fscrypt_private.h
>   fscrypt: unexport fscrypt_get_encryption_info()
>   fscrypt: allow deleting files with unsupported encryption policy
> 
>  fs/crypto/fname.c           |  8 +++-
>  fs/crypto/fscrypt_private.h | 28 ++++++++++++++
>  fs/crypto/hooks.c           | 16 +++++++-
>  fs/crypto/keysetup.c        | 20 ++++++++--
>  fs/crypto/policy.c          | 22 +++++++----
>  fs/ext4/dir.c               | 16 ++------
>  fs/ext4/namei.c             | 10 +----
>  fs/f2fs/dir.c               | 10 +----
>  fs/ubifs/dir.c              | 11 +-----
>  include/linux/fscrypt.h     | 75 +++++++++++++++++++------------------
>  10 files changed, 126 insertions(+), 90 deletions(-)
> 
> 
> base-commit: 4a4b8721f1a5e4b01e45b3153c68d5a1014b25de

All applied to fscrypt.git#master for 5.11.

- Eric