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From:   Andreas Dilger <adilger@dilger.ca>
Message-Id: <047AD2C4-4E34-4325-B2B6-02E240ED50DD@dilger.ca>
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Subject: Re: [PATCH 0/9] Allow deleting files with unsupported encryption
 policy
Date:   Wed, 2 Dec 2020 15:25:25 -0700
In-Reply-To: <X8gCKTx96rXUMh0i@gmail.com>
Cc:     linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org
To:     Eric Biggers <ebiggers@kernel.org>
References: <20201125002336.274045-1-ebiggers@kernel.org>
 <X8gCKTx96rXUMh0i@gmail.com>
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On Dec 2, 2020, at 2:07 PM, Eric Biggers <ebiggers@kernel.org> wrote:
>=20
> On Tue, Nov 24, 2020 at 04:23:27PM -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.
>>=20
>> 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.
>>=20
>> 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.
>>=20
>> The actual fix is in patch 9, so see that for more details.
>>=20
>> Patches 1-8 are cleanups that prepare for the actual fix by removing
>> direct use of fscrypt_get_encryption_info() by filesystems.
>>=20
>> This patchset applies to branch "master" (commit 4a4b8721f1a5) of
>> https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git.
>>=20
>> 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
>>=20
>> 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(-)
>>=20
>>=20
>> base-commit: 4a4b8721f1a5e4b01e45b3153c68d5a1014b25de
>=20
> Any more comments on this patch series?

I think the general idea makes sense.  I'll review the ext4 patches in =
the series.


Cheers, Andreas


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