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From: Florian Weimer <fw@deneb.enyo.de>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-xfs@vger.kernel.org, libc-alpha@sourceware.org,
	linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk
Subject: Re: XFS reports lchmod failure, but changes file system contents
Date: Wed, 12 Feb 2020 19:50:01 +0100
Message-ID: <87pnejmyhy.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <20200212181128.GA31394@infradead.org> (Christoph Hellwig's message of "Wed, 12 Feb 2020 10:11:28 -0800")

* Christoph Hellwig:

> xfs doesn't seem all that different from the other file systems,
> so I suspect you'll also see it with other on-disk file systems.
> We probably need a check high up in the chmod and co code to reject
> the operation early for O_PATH file descriptors pointing to symlinks.

We will change the glibc emulation to avoid trying to lchmod symbolic
links in this way.  This will avoid triggering the kernel bug.

(We'd really like to get a proper fchmodat system call with a flags
argument, though, for AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW.)

And part of my testing was wrong, this is a symbolic-link-only issue.

  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 11:48 Florian Weimer
2020-02-12 12:15 ` Florian Weimer
2020-02-12 16:16 ` Darrick J. Wong
2020-02-12 18:11   ` Christoph Hellwig
2020-02-12 18:37     ` Darrick J. Wong
2020-02-12 19:15       ` Florian Weimer
2020-02-12 19:51         ` Al Viro
2020-02-12 19:55           ` Rich Felker
2020-02-12 20:01           ` Florian Weimer
2020-02-12 20:17             ` Andreas Schwab
2020-02-12 20:19               ` Rich Felker
2020-02-12 20:26                 ` Florian Weimer
2020-02-12 20:38                   ` Rich Felker
2020-02-12 20:27                 ` Al Viro
2020-02-12 20:36                   ` Rich Felker
2020-02-12 20:18             ` Rich Felker
2020-02-12 20:38             ` Paul Eggert
2020-02-21  4:09             ` Aleksa Sarai
2020-02-21  5:02               ` Al Viro
2020-02-21  5:21                 ` Aleksa Sarai
2020-02-12 18:50     ` Florian Weimer [this message]
2020-02-12 18:55       ` Christoph Hellwig

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