Re: [PATCH] iouring:added boundary value check for io_uring_group systl

[Subramanya Swamy]

Hi Jeff,

           Thank you for reviewing the patch.

On 16/01/24 23:16, Jeff Moyer wrote:
> Subramanya Swamy <subramanya.swamy.linux@xxxxxxxxx> writes:
>
> > /proc/sys/kernel/io_uring_group takes gid as input
> > added boundary value check to accept gid in range of
> > 0<=gid<=4294967294 & Documentation is updated for same
> Thanks for the patch.  You're right, the current code artificially
> limits the maximum group id.
>
> > Signed-off-by: Subramanya Swamy <subramanya.swamy.linux@xxxxxxxxx>
> > ---
> >   Documentation/admin-guide/sysctl/kernel.rst | 9 ++++-----
> >   io_uring/io_uring.c                         | 8 ++++++--
> >   2 files changed, 10 insertions(+), 7 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
> > index 6584a1f9bfe3..3f96007aa971 100644
> > --- a/Documentation/admin-guide/sysctl/kernel.rst
> > +++ b/Documentation/admin-guide/sysctl/kernel.rst
> > @@ -469,11 +469,10 @@ shrinks the kernel's attack surface.
> >   io_uring_group
> >   ==============
> >   
> > -When io_uring_disabled is set to 1, a process must either be
> > -privileged (CAP_SYS_ADMIN) or be in the io_uring_group group in order
> > -to create an io_uring instance.  If io_uring_group is set to -1 (the
> > -default), only processes with the CAP_SYS_ADMIN capability may create
> > -io_uring instances.
> > +When io_uring_disabled is set to 1, only processes with the
> > +CAP_SYS_ADMIN may create io_uring instances or process must be in the
> > +io_uring_group group in order to create an io_uring_instance.
> > +io_uring_group is set to 0.This is the default setting.
> You are changing the default from an invalid group to the root group.  I
> guess that's ok, but I'd rather keep it the way it is.  The text is a
> bit repetitive.  Why not just this?
>
> "When io_uring_disabled is set to 1, a process must either be
>   privileged (CAP_SYS_ADMIN) or be in the io_uring_group group in order
>   to create an io_uring instance."

Yes this looks neat , will add in v2

> > diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> > index 09b6d860deba..0ed91b69643d 100644
> > --- a/io_uring/io_uring.c
> > +++ b/io_uring/io_uring.c
> > @@ -146,7 +146,9 @@ static void io_queue_sqe(struct io_kiocb *req);
> >   struct kmem_cache *req_cachep;
> >   
> >   static int __read_mostly sysctl_io_uring_disabled;
> > -static int __read_mostly sysctl_io_uring_group = -1;
> > +static unsigned int __read_mostly sysctl_io_uring_group;
> > +static unsigned int min_gid;
> > +static unsigned int max_gid  = 4294967294;  /*4294967294 is the max guid*/
> Right, INVALID_GID is -1.
>
> >   #ifdef CONFIG_SYSCTL
> >   static struct ctl_table kernel_io_uring_disabled_table[] = {
> > @@ -164,7 +166,9 @@ static struct ctl_table kernel_io_uring_disabled_table[] = {
> >   		.data		= &sysctl_io_uring_group,
> >   		.maxlen		= sizeof(gid_t),
> >   		.mode		= 0644,
> > -		.proc_handler	= proc_dointvec,
> > +		.proc_handler	= proc_douintvec_minmax,
> > +		.extra1         = &min_gid,
> This should be SYSCTL_ZERO.

will change this to SYSCTL_ZERO in v2

> > +		.extra2         = &max_gid,
> >   	},
> >   	{},
> >   };
> Thanks!
> Jeff
--
Best Regards
Subramanya