Re: [PATCH v3 1/1] io_uring: add a sysctl to disable io_uring system-wide

[Jeff Moyer <jmoyer@redhat.com>]

Hi, Andres,

Andres Freund <andres@anarazel.de> writes:

> Hi,
>
> On 2023-06-30 15:10:03 +0000, Matteo Rizzo wrote:
>> Introduce a new sysctl (io_uring_disabled) which can be either 0, 1,
>> or 2. When 0 (the default), all processes are allowed to create io_uring
>> instances, which is the current behavior. When 1, all calls to
>> io_uring_setup fail with -EPERM unless the calling process has
>> CAP_SYS_ADMIN. When 2, calls to io_uring_setup fail with -EPERM
>> regardless of privilege.
>
> Hm, is there a chance that instead of requiring CAP_SYS_ADMIN, a certain group
> could be required (similar to hugetlb_shm_group)? Requiring CAP_SYS_ADMIN
> could have the unintended consequence of io_uring requiring tasks being run
> with more privileges than needed... Or some other more granular way of
> granting the right to use io_uring?

That's fine with me, so long as there is still an option to completely
disable io_uring.

> ISTM that it'd be nice if e.g. a systemd service specification could allow
> some services to use io_uring, without allowing it for everyone, or requiring
> to run services effectively as root.

Do you have a proposal for how that would work?  Why is this preferable
to using a group?

Cheers,
Jeff