Re: [RFC PATCH v5 02/19] fscrypt: export fscrypt_base64_encode and fscrypt_base64_decode

Jeff Layton
2021-04-08T16:22:43Z

On Wed, 2021-04-07 at 18:06 -0700, Eric Biggers wrote:
> On Fri, Mar 26, 2021 at 01:32:10PM -0400, Jeff Layton wrote:
> > Ceph will need to base64-encode some encrypted filenames, so make
> > these routines, and FSCRYPT_BASE64_CHARS available to modules.
> >
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
>
> It would be helpful to have a quick explanation here about *why* ceph has to do
> base64 encoding/decoding itself.
>

Sure. I'll plan to flesh out the changelogs a bit more before the next
posting.

The basic problem is that we want to use printable filenames for storage
on the MDS, but we don't want to tie the format we use to the fscrypt
nokey name format.

So, we have our own nokey name format that we use that's quite similar
to the one in fscrypt. So similar in fact, that we want to use the same
base64 encoding scheme that fscrypt uses for this -- hence the need to
make these available to modules.
--
Jeff Layton <jlayton@kernel.org>