linux-kernel - Re: [PATCH 2/2] vfs: support statx(..., NULL, AT_EMPTY

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Message-ID: <CAAhV-H4Z_BCWRJoCOh4Cei3eFCn_wvFWxA7AzWfNxYtNqUwBPA@mail.gmail.com>
Date: Tue, 2 Jul 2024 23:36:50 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: Xi Ruoyao <xry111@...111.site>, Mateusz Guzik <mjguzik@...il.com>, 
	Christian Brauner <brauner@...nel.org>, Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	io-uring@...r.kernel.org, Jens Axboe <axboe@...nel.dk>, 
	Linus Torvalds <torvalds@...ux-foundation.org>, loongarch@...ts.linux.dev
Subject: Re: [PATCH 2/2] vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)

Hi, Arnd,

On Mon, Jul 1, 2024 at 7:59 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Sun, Jun 30, 2024, at 04:39, Xi Ruoyao wrote:
> > On Sun, 2024-06-30 at 09:40 +0800, Huacai Chen wrote:
> >> >
> >> > Yes, both Linus and Christian hates introducing a new AT_ flag for
> >> > this.
> >> >
> >> > This patch just makes statx(fd, NULL, AT_EMPTY_PATH, ...) behave
> >> > like
> >> > statx(fd, "", AT_EMPTY_PATH, ...) instead.  NULL avoids the
> >> > performance
> >> > issue and it's also audit-able by seccomp BPF.
> >> To be honest, I still want to restore __ARCH_WANT_NEW_STAT. Because
> >> even if statx() becomes audit-able, it is still blacklisted now.
> >
> > Then patch the sandbox to allow it.
> >
> > The sandbox **must** be patched anyway or it'll be broken on all 32-bit
> > systems after 2037.  [Unless they'll unsupport all 32-bit systems before
> > 2037.]
>
> More importantly, the sandbox won't be able to support any 32-bit
> targets that support running after 2037, regardless of how long
> the sandbox supports them: if you turn off COMPAT_32BIT_TIME today
> in order to be sure those don't get called by accident, the
> fallback is immediately broken.
Would you mind if I restore newstat for LoongArch64 even if this patch exist?

Huacai

>
>       Arnd