On Mon, Dec 19, 2016 at 02:20:14PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> Now that fscrypt_has_permitted_context() compares the fscrypt_context
> rather than the fscrypt_info when needed, it is no longer necessary to
> delay fscrypt_has_permitted_context() from ->lookup() to ->open() for
> regular files, as introduced in commit ff978b09f973 ("ext4 crypto: move
> context consistency check to ext4_file_open()"). Therefore the check in
> ->open(), along with the dget_parent() hack, can be removed. It's also
> no longer necessary to check the file type before calling
> fscrypt_has_permitted_context().
There's a downside to this change. The change in the earlier commit
of this series teaches fscrypt_has_permitted_context() can fall back
to comparing the fscrypt_context. That's all very well and good, but
it means that if you do a ls -l of an encrypted directory, and the key
is not present, we will have to do an xattr lookup for every file in
that directory. Even if the key is present, it will force the
derivation of the per-file key of every file in that directory,
regardless of whether the file is opened or not.
- Ted
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