Messages in this thread | | | From | Arnd Bergmann <> | Date | Tue, 22 Sep 2020 09:23:37 +0200 | Subject | Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag |
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On Tue, Sep 22, 2020 at 8:32 AM Pavel Begunkov <asml.silence@gmail.com> wrote: > On 22/09/2020 03:58, Andy Lutomirski wrote: > > On Mon, Sep 21, 2020 at 5:24 PM Pavel Begunkov <asml.silence@gmail.com> wrote: > > I may be looking at a different kernel than you, but aren't you > > preventing creating an io_uring regardless of whether SQPOLL is > > requested? > > I diffed a not-saved file on a sleepy head, thanks for noticing. > As you said, there should be an SQPOLL check. > > ... > if (ctx->compat && (p->flags & IORING_SETUP_SQPOLL)) > goto err;
Wouldn't that mean that now 32-bit containers behave differently between compat and native execution?
I think if you want to prevent 32-bit applications from using SQPOLL, it needs to be done the same way on both to be consistent:
if ((!IS_ENABLED(CONFIG_64BIT) || ctx->compat) && (p->flags & IORING_SETUP_SQPOLL)) goto err;
I don't really see how taking away SQPOLL from 32-bit tasks is any better than just preventing access to the known-broken files as Al suggested, or adding the hack to make it work as in Christoph's original patch.
Can we expect all existing and future user space to have a sane fallback when IORING_SETUP_SQPOLL fails?
Arnd
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