From: "Demi M. Obenour" <demiobenour@gmail.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: "open list:FILESYSTEMS (VFS and infrastructure)"
<linux-fsdevel@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] Return -EINVAL if userspace passes bogus flags to open()
Date: Tue, 12 Feb 2019 18:00:44 -0500 [thread overview]
Message-ID: <ce981281-bb3a-a539-8d5a-b2d88107d4c0@gmail.com> (raw)
In-Reply-To: <20190212203809.GK2217@ZenIV.linux.org.uk>
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On 2/12/19 3:38 PM, Al Viro wrote:
> On Tue, Feb 12, 2019 at 09:54:47AM -0500, demiobenour@gmail.com wrote:
>> From: "Demi M. Obenour" <demiobenour@gmail.com>
>>
>> While testing the O_PATHSTATIC patch, I discovered that Linux does not
>> return any error if an invalid flag is passed to open(2). This prevents
>> adding new flags without a (minor) risk of breaking userspace.
>> Therefore, add a check for invalid flags, and return -EINVAL if any are
>> found.
>
> ... which would qualtify as userland ABI breakage all by itself.
>
I suspect that very few (if any) programs pass invalid flags to open().
Additionally, O_DIRECT was added in Linux 2.4, even though it had
previously been ignored. If someone knows of a real program that does,
I can instead create an open2() syscall, but I would prefer to avoid that.
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prev parent reply other threads:[~2019-02-12 23:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 14:54 [PATCH 1/4] Add path resolution flag LOOKUP_NEVER_FOLLOW demiobenour
2019-02-12 14:54 ` [PATCH 2/4] Expose O_PATHSTATIC to userspace demiobenour
2019-02-12 20:18 ` Andreas Dilger
2019-02-12 22:41 ` Demi M. Obenour
2019-02-12 14:54 ` [PATCH 3/4] Add AT_PATHSTATIC to linkat() demiobenour
2019-02-12 14:54 ` [PATCH 4/4] Return -EINVAL if userspace passes bogus flags to open() demiobenour
2019-02-12 20:38 ` Al Viro
2019-02-12 23:00 ` Demi M. Obenour [this message]
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