Re: Practical questions about locking and re-encrypting

[Tyler Hicks <tyhicks@canonical.com>]

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On 2014-09-22 17:32:57, Kenneth Waegeman wrote:
> Hi all,

Hi Kenneth

> 
> 
> We want to use ecryptfs on GPFS. How does ecryptfs handles locking if an
> encrypted directory is mounted on different boxes ? Is data corruption
> possible while writing?

eCryptfs is not well suited for being stacked on top of a distributed
file system such as GPFS.

That would result in each node having its own eCryptfs mount. Each
eCryptfs mount has its own page cache. eCryptfs doesn't do any sort of
coordination between remote mounts and there's no way for the lower
filesystem to make eCryptfs aware that file contents, which may be in
the eCryptfs page cache, have been modified by a remote node.

That means that if a file is read into the eCryptfs page cache on node A
and then that file is updated on node B, node A will never know an
update has been made and will never invalidate the old, cached file
contents from its page cache.

> 
> Another question: Is there an easy way to re-encrypt a directory with
> another key? (when having compromised key or so).

Unfortunately, no. You'd need to set up a new eCryptfs mount, with a new
key, and copy the files between the two eCryptfs mounts.

Tyler

> 
> 
> Thank you!!
> 
> Kenneth
> 
> 
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