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From: Christoph Hellwig <hch@lst.de>
To: Christian Brauner <brauner@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
	martin.lau@kernel.org, cyphar@cyphar.com, lennart@poettering.net,
	linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: fd == 0 means AT_FDCWD BPF_OBJ_GET commands
Date: Wed, 17 May 2023 14:05:28 +0200	[thread overview]
Message-ID: <20230517120528.GA17087@lst.de> (raw)
In-Reply-To: <20230517-allabendlich-umgekehrt-8cc81f8313ac@brauner>

On Wed, May 17, 2023 at 11:11:24AM +0200, Christian Brauner wrote:
> Adding fsdevel so we're aware of this quirk.
> 
> So I'm not sure whether this was ever discussed on fsdevel when you took
> the decision to treat fd 0 as AT_FDCWD or in general treat fd 0 as an
> invalid value.

I've never heard of this before, and I think it is compltely
unacceptable. 0 ist just a normal FD, although one that happens to
have specific meaning in userspace as stdin.

> 
> If it was discussed then great but if not then I would like to make it
> very clear that if in the future you decide to introduce custom
> semantics for vfs provided infrastructure - especially when exposed to
> userspace - that you please Cc us.

I don't think it's just the future.  We really need to undo this ASAP.


  reply	other threads:[~2023-05-17 12:08 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230516001348.286414-1-andrii@kernel.org>
     [not found] ` <20230516001348.286414-2-andrii@kernel.org>
     [not found]   ` <20230516-briefe-blutzellen-0432957bdd15@brauner>
     [not found]     ` <CAEf4BzafCCeRm9M8pPzpwexadKy5OAEmrYcnVpKmqNJ2tnSVuw@mail.gmail.com>
2023-05-17  9:11       ` fd == 0 means AT_FDCWD BPF_OBJ_GET commands Christian Brauner
2023-05-17 12:05         ` Christoph Hellwig [this message]
2023-05-17 16:17           ` Alexei Starovoitov
2023-05-17 21:48             ` Alexei Starovoitov
2023-05-18  8:38             ` Christian Brauner
2023-05-18 14:30               ` Theodore Ts'o
2023-05-18 16:25               ` Alexei Starovoitov
2023-05-18 16:33                 ` Matthew Wilcox
2023-05-18 17:22                   ` Christian Brauner
2023-05-18 17:20                 ` Christian Brauner
2023-05-18 17:33                   ` Linus Torvalds
2023-05-18 18:21                     ` Christian Brauner
2023-05-18 18:26                   ` Alexei Starovoitov
     [not found]                     ` <CAHk-=whg-ygwrxm3GZ_aNXO=srH9sZ3NmFqu0KkyWw+wgEsi6g@mail.gmail.com>
2023-05-19  4:44                       ` Alexei Starovoitov
2023-05-19  8:13                         ` Christian Brauner
2023-05-19 14:27                           ` Theodore Ts'o
2023-05-19 17:51                         ` Linus Torvalds
2023-05-23  7:49                         ` Lennart Poettering
2023-05-23 17:25                           ` Andrii Nakryiko
2023-08-26  4:27                         ` Al Viro
2023-05-18 21:56         ` Andrii Nakryiko

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