From: maobibo <maobibo@loongson.cn>
To: Arnd Bergmann <arnd@arndb.de>,
Huacai Chen <chenhuacai@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>
Cc: loongarch@lists.linux.dev,
Linux-Arch <linux-arch@vger.kernel.org>,
Xuefeng Li <lixuefeng@loongson.cn>, guoren <guoren@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
linux-kernel@vger.kernel.org, loongson-kernel@lists.loongnix.cn,
stable@vger.kernel.org
Subject: Re: [PATCH] LoongArch: Define __ARCH_WANT_NEW_STAT in unistd.h
Date: Wed, 15 May 2024 17:30:21 +0800 [thread overview]
Message-ID: <3937d6b1-119b-195e-8b9b-314a0bfbeaeb@loongson.cn> (raw)
In-Reply-To: <f92e23be-3f3f-4bc6-8711-3bcf6beb7fa2@app.fastmail.com>
On 2024/5/11 下午8:17, Arnd Bergmann wrote:
> On Sat, May 11, 2024, at 12:01, Huacai Chen wrote:
>> Chromium sandbox apparently wants to deny statx [1] so it could properly
>> inspect arguments after the sandboxed process later falls back to fstat.
>> Because there's currently not a "fd-only" version of statx, so that the
>> sandbox has no way to ensure the path argument is empty without being
>> able to peek into the sandboxed process's memory. For architectures able
>> to do newfstatat though, glibc falls back to newfstatat after getting
>> -ENOSYS for statx, then the respective SIGSYS handler [2] takes care of
>> inspecting the path argument, transforming allowed newfstatat's into
>> fstat instead which is allowed and has the same type of return value.
>>
>> But, as LoongArch is the first architecture to not have fstat nor
>> newfstatat, the LoongArch glibc does not attempt falling back at all
>> when it gets -ENOSYS for statx -- and you see the problem there!
>
> My main objection here is that this is inconsistent with 32-bit
> architectures: we normally have newfstatat() on 64-bit
> architectures but fstatat64() on 32-bit ones. While loongarch64
> is the first 64-bit one that is missing newfstatat(), we have
> riscv32 already without fstatat64().
>
> Importantly, we can't just add fstatat64() on riscv32 because
> there is no time64 version for it other than statx(), and I don't
> want the architectures to diverge more than necessary.
yes, I agree. Normally there is newfstatat() on 64-bit architectures but
fstatat64() on 32-bit ones.
I do not understand why fstatat64() can be added for riscv32 still.
32bit timestamp seems works well for the present, it is valid until
(0x1UL << 32) / 365 / 24 / 3600 + 1970 == 2106 year. Year 2106 should
be enough for 32bit system.
Regards
Bibo Mao
> I would not mind adding a variant of statx() that works for
> both riscv32 and loongarch64 though, if it gets added to all
> architectures.
>
> Arnd
>
next prev parent reply other threads:[~2024-05-15 9:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-11 10:01 [PATCH] LoongArch: Define __ARCH_WANT_NEW_STAT in unistd.h Huacai Chen
2024-05-11 12:17 ` Arnd Bergmann
2024-05-11 14:28 ` Huacai Chen
2024-05-11 15:38 ` Arnd Bergmann
2024-05-12 3:11 ` Huacai Chen
2024-05-12 7:52 ` Arnd Bergmann
2024-05-15 9:30 ` maobibo [this message]
2024-05-15 14:25 ` Arnd Bergmann
2024-05-16 2:52 ` maobibo
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