From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
LSM List <linux-security-module@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
"Theodore Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-integrity@vger.kernel.org
Subject: Re: [RFC PATCH 3/3] fs: detect that the i_rwsem has already been taken exclusively
Date: Sun, 1 Oct 2017 16:15:07 -0700 [thread overview]
Message-ID: <CA+55aFwV=mO4NjJ2nqOsme7Pg_Lno7hPO6o+ahf-qSpunm9scA@mail.gmail.com> (raw)
In-Reply-To: <20171001223402.GG15067@dastard>
On Sun, Oct 1, 2017 at 3:34 PM, Dave Chinner <david@fromorbit.com> wrote:
>
> We already have a change counter on the inode, which is modified on
> any data or metadata write (i_version) under filesystem locks. The
> i_version counter has well defined semantics - it's required by
> NFSv4 to increment on any metadata or data change - so we should be
> able to rely on it's behaviour to implement IMA as well.
I actually think i_version has exactly the wrong semantics.
Afaik, it doesn't actually version the file _data_ at all, it only
versions "inode itself changed".
But I might have missed something obvious. The updates are hidden in
some odd places sometimes.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: torvalds@linux-foundation.org (Linus Torvalds)
To: linux-security-module@vger.kernel.org
Subject: [RFC PATCH 3/3] fs: detect that the i_rwsem has already been taken exclusively
Date: Sun, 1 Oct 2017 16:15:07 -0700 [thread overview]
Message-ID: <CA+55aFwV=mO4NjJ2nqOsme7Pg_Lno7hPO6o+ahf-qSpunm9scA@mail.gmail.com> (raw)
In-Reply-To: <20171001223402.GG15067@dastard>
On Sun, Oct 1, 2017 at 3:34 PM, Dave Chinner <david@fromorbit.com> wrote:
>
> We already have a change counter on the inode, which is modified on
> any data or metadata write (i_version) under filesystem locks. The
> i_version counter has well defined semantics - it's required by
> NFSv4 to increment on any metadata or data change - so we should be
> able to rely on it's behaviour to implement IMA as well.
I actually think i_version has exactly the wrong semantics.
Afaik, it doesn't actually version the file _data_ at all, it only
versions "inode itself changed".
But I might have missed something obvious. The updates are hidden in
some odd places sometimes.
Linus
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next prev parent reply other threads:[~2017-10-01 23:15 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-28 12:39 [RFC PATCH 0/3] define new read_iter file operation rwf flag Mimi Zohar
2017-09-28 12:39 ` Mimi Zohar
2017-09-28 12:39 ` [RFC PATCH 1/3] fs: define new read_iter " Mimi Zohar
2017-09-28 12:39 ` Mimi Zohar
2017-09-28 13:54 ` Matthew Wilcox
2017-09-28 13:54 ` Matthew Wilcox
2017-09-28 14:33 ` Mimi Zohar
2017-09-28 14:33 ` Mimi Zohar
2017-09-28 15:51 ` Linus Torvalds
2017-09-28 15:51 ` Linus Torvalds
2017-09-28 12:39 ` [RFC PATCH 2/3] integrity: use call_read_iter to calculate the file hash Mimi Zohar
2017-09-28 12:39 ` Mimi Zohar
2017-09-28 12:39 ` [RFC PATCH 3/3] fs: detect that the i_rwsem has already been taken exclusively Mimi Zohar
2017-09-28 12:39 ` Mimi Zohar
2017-09-28 22:02 ` Dave Chinner
2017-09-28 22:02 ` Dave Chinner
2017-09-28 23:39 ` Linus Torvalds
2017-09-28 23:39 ` Linus Torvalds
2017-09-29 0:12 ` Mimi Zohar
2017-09-29 0:12 ` Mimi Zohar
2017-09-29 0:12 ` Mimi Zohar
2017-09-29 0:33 ` Linus Torvalds
2017-09-29 0:33 ` Linus Torvalds
2017-09-29 1:53 ` Mimi Zohar
2017-09-29 1:53 ` Mimi Zohar
2017-09-29 1:53 ` Mimi Zohar
2017-09-29 3:26 ` Linus Torvalds
2017-09-29 3:26 ` Linus Torvalds
2017-10-01 1:33 ` Eric W. Biederman
2017-10-01 1:33 ` Eric W. Biederman
[not found] ` <CA+55aFx726wT4VprN-sHm6s8Q_PV_VjhTBC4goEbMcerYU1Tig@mail.gmail.com>
2017-10-01 12:08 ` Mimi Zohar
2017-10-01 12:08 ` Mimi Zohar
2017-10-01 12:08 ` Mimi Zohar
2017-10-01 18:41 ` Linus Torvalds
2017-10-01 18:41 ` Linus Torvalds
2017-10-01 22:34 ` Dave Chinner
2017-10-01 22:34 ` Dave Chinner
2017-10-01 23:15 ` Linus Torvalds [this message]
2017-10-01 23:15 ` Linus Torvalds
2017-10-02 3:54 ` Dave Chinner
2017-10-02 3:54 ` Dave Chinner
2017-10-01 23:42 ` Mimi Zohar
2017-10-01 23:42 ` Mimi Zohar
2017-10-01 23:42 ` Mimi Zohar
2017-10-02 3:25 ` Eric W. Biederman
2017-10-02 3:25 ` Eric W. Biederman
2017-10-02 3:25 ` Eric W. Biederman
2017-10-02 12:25 ` Mimi Zohar
2017-10-02 12:25 ` Mimi Zohar
2017-10-02 12:25 ` Mimi Zohar
2017-10-02 4:35 ` Dave Chinner
2017-10-02 4:35 ` Dave Chinner
2017-10-02 4:35 ` Dave Chinner
2017-10-02 4:35 ` Dave Chinner
2017-10-02 12:09 ` Mimi Zohar
2017-10-02 12:09 ` Mimi Zohar
2017-10-02 12:09 ` Mimi Zohar
2017-10-02 12:43 ` Jeff Layton
2017-10-02 12:43 ` Jeff Layton
2017-10-01 22:06 ` Eric W. Biederman
2017-10-01 22:06 ` Eric W. Biederman
2017-10-01 22:20 ` Linus Torvalds
2017-10-01 22:20 ` Linus Torvalds
2017-10-01 23:54 ` Mimi Zohar
2017-10-01 23:54 ` Mimi Zohar
2017-10-01 23:54 ` Mimi Zohar
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