linux-kernel - Re: [PATCHv2] io_uring: Support calling io_uring

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 16 Feb 2023 04:05:47 -0800
From:   Josh Triplett <josh@...htriplett.org>
To:     Dylan Yudaken <dylany@...a.com>
Cc:     "axboe@...nel.dk" <axboe@...nel.dk>,
        "asml.silence@...il.com" <asml.silence@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "io-uring@...r.kernel.org" <io-uring@...r.kernel.org>
Subject: Re: [PATCHv2] io_uring: Support calling io_uring_register with a
 registered ring fd

On Thu, Feb 16, 2023 at 09:35:44AM +0000, Dylan Yudaken wrote:
> On Tue, 2023-02-14 at 16:42 -0800, Josh Triplett wrote:
> > @@ -4177,17 +4177,37 @@ SYSCALL_DEFINE4(io_uring_register, unsigned
> > int, fd, unsigned int, opcode,
> >         struct io_ring_ctx *ctx;
> >         long ret = -EBADF;
> >         struct fd f;
> > +       bool use_registered_ring;
> > +
> > +       use_registered_ring = !!(opcode &
> > IORING_REGISTER_USE_REGISTERED_RING);
> > +       opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
> >  
> >         if (opcode >= IORING_REGISTER_LAST)
> >                 return -EINVAL;
> >  
> > -       f = fdget(fd);
> > -       if (!f.file)
> > -               return -EBADF;
> > +       if (use_registered_ring) {
> > +               /*
> > +                * Ring fd has been registered via
> > IORING_REGISTER_RING_FDS, we
> > +                * need only dereference our task private array to
> > find it.
> > +                */
> > +               struct io_uring_task *tctx = current->io_uring;
> >  
> > -       ret = -EOPNOTSUPP;
> > -       if (!io_is_uring_fops(f.file))
> > -               goto out_fput;
> > +               if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
> > +                       return -EINVAL;
> > +               fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
> > +               f.file = tctx->registered_rings[fd];
> > +               f.flags = 0;
> > +               if (unlikely(!f.file))
> > +                       return -EBADF;
> > +               opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
> 
> ^ this line looks duplicated at the top of the function?

Good catch!

Jens, since you've already applied this, can you remove this line or
would you like a patch doing so?

> Also - is there a liburing regression test for this?

Userspace, including test: https://github.com/axboe/liburing/pull/664