Eric Biggers <ebiggers@xxxxxxxxxx> writes:
> The code looks fine, but the explanation needs some tweaks:
>
> On Mon, Apr 04, 2022 at 11:25:54AM +0100, Luís Henriques wrote:
>> fscrypt keys have used the $FSTYP as prefix. However this format is being
>> deprecated -- newer kernels already allow the usage of the generic
>> 'fscrypt:' prefix for ext4 and f2fs. This patch allows the usage of this
>> new prefix for testing filesystems that have never supported the old
>> format, but keeping the $FSTYP prefix for filesystems that support it, so
>> that old kernels can be tested.
>
> This explanation is inconsistent with the code, which uses FSTYP for only ext4
> and f2fs, and fscrypt for everything else including ubifs.
>
> A better explanation would be something like "Only use $FSTYP on filesystems
> that never supported the 'fscrypt' prefix, i.e. ext4 and f2fs."
>
>> +# Keys are named $FSTYP:KEYDESC where KEYDESC is the 16-character key descriptor
>> +# hex string. Newer kernels (ext4 4.8 and later, f2fs 4.6 and later) also allow
>> +# the common key prefix "fscrypt:" in addition to their filesystem-specific key
>> +# prefix ("ext4:", "f2fs:"). It would be nice to use the common key prefix, but
>> +# for now use the filesystem- specific prefix for these 2 filesystems to make it
>> +# possible to test older kernels, and the "fscrypt" prefix for anything else.
>> +_get_fs_keyprefix()
>
> The first part of this comment sort of implies that FSTYP is the default and
> "fscrypt" is the exception, but it should be the other way around.
>
> How about:
>
> # When fscrypt keys are added using the legacy mechanism (process-subscribed
> # keyrings rather than filesystem keyrings), they are normally named
> # "fscrypt:KEYDESC" where KEYDESC is the 16-character key descriptor hex string.
> # However, ext4 and f2fs didn't add support for the "fscrypt" prefix until
> # kernel v4.8 and v4.6, respectively. Before that, they used "ext4" and "f2fs",
> # respectively. To allow testing ext4 and f2fs encryption on kernels older than
> # this, we use these filesystem-specific prefixes for ext4 and f2fs.
Doh! Yes, of course I need to adjust the documentation. Sorry, I'll send
v3 shortly. Thanks!
Cheers,
--
Luís
