On Thu, Oct 19, 2017 at 2:14 AM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Oct 18, 2017 at 02:38:38PM +0200, Ilya Dryomov wrote:
>> Check for CAP_SYS_ADMIN before calling into the driver, similar to
>> blkdev_flushbuf(). This is safer and can spare a check in the driver.
>>
>> (Currently BLKROSET is overridden by md and rbd, rbd is missing the
>> check. md has the check, but it covers a lot more than BLKROSET.)
>>
>> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
>> ---
>> Al, this appears to go back to your "[PATCH] block ioctl cleanup",
>> history commit c6973580141c. 2002 was a long time ago, but still ;)
>> Was there a reason you made BLKFLSBUF check for CAP_SYS_ADMIN before
>> ->ioctl() and BLKROSET after?
>
> It was a long time ago, indeed... The funny part is, at the time
> there had been no ->ioctl() instances with unusual BLKROSET handling
> left; I really don't remember what had left to the override for
> those remaining and (assuming it hadn't been a plain and simple braino)
> the reasons for leaving the check to drivers that might eventually
> want to add such overrides would be in whatever discussion that
> had lead to leaving that override...
>
> There was a *lot* of patch series (semi)manual reordering/rebasing, so
> it might have easily been braindamage on conflict resolution during
> rebase.
>
> gendisk work had been literally hundreds of patches all over the
> drivers/* over the summer and autumn of 2002; I have bits and pieces of
> email archives from back then, but quick grep doesn't catch any
> discussions along those lines and they are incomplete ;-/
>
> Anyway,
> a) I don't see any reason for drivers to relax the checks on
> BLKROSET and rbd lacking those is almost certainly a bug
> b) Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> c) I can push it through vfs tree, but it would probably make
> more sense block one.
Jens, can you pick this up for 4.15?
Thanks,
Ilya
