From: Mimi Zohar <zohar@linux.ibm.com>
To: "Theodore Y. Ts'o" <tytso@mit.edu>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Biggers <ebiggers@kernel.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Dave Chinner <david@fromorbit.com>,
linux-f2fs-devel@lists.sourceforge.net,
Christoph Hellwig <hch@infradead.org>,
linux-fscrypt@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-ext4@vger.kernel.org
Subject: Re: Proposal: Yet another possible fs-verity interface
Date: Tue, 12 Feb 2019 09:44:39 -0500 [thread overview]
Message-ID: <1549982679.12743.248.camel@linux.ibm.com> (raw)
In-Reply-To: <20190212051237.GQ23000@mit.edu>
> At that point, the merkle tree thing ends up fairly equivalent to
the
> > IMA "measurement" thing, with the exception that the filesystem *may*
> > optimize it to be long-term. Hmm?
>
> Well, except that it's just a less efficient way of doing IMA
> "measurement" (if the file system doesn't support Merkle tree
> storage).
>
> So adding that complexity is, in my view, not really worth it, since I
> very much doubt anyone would use a slower scheme. I think the much
> better model is that fsverity is for file system where you can store
> the Merkle tree (and it's really not that hard for most file systems
> to store it); and if you are using a file system which doesn't, use
> IMA in good health.
Ted, one of the problems with IMA is that the file hash/signature
verification is at file open. It isn't aware when files are brought
in from cache. Does fs-verity re-verify blocks as they're restored
from cache? For some use cases, that might justify the up front cost
associated with building the Merkle tree.
Mimi
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next prev parent reply other threads:[~2019-02-12 14:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 3:11 Proposal: Yet another possible fs-verity interface Theodore Y. Ts'o
2019-02-08 19:10 ` James Bottomley
2019-02-09 20:38 ` Linus Torvalds
2019-02-10 14:06 ` Mimi Zohar
2019-02-12 5:31 ` Theodore Y. Ts'o
2019-02-12 13:06 ` Mimi Zohar
2019-02-12 17:24 ` Theodore Y. Ts'o
2019-02-12 18:42 ` Eric Biggers
2019-02-12 5:12 ` Theodore Y. Ts'o
2019-02-12 14:44 ` Mimi Zohar [this message]
2019-02-12 17:11 ` Theodore Y. Ts'o
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