On 6/17/19 3:29 PM, Daniel P. Berrangé wrote:
On Thu, Apr 25, 2019 at 10:19:54AM +0200, Michal Privoznik wrote:
This effectively reverts d7420430ce6 and adds new code.
Here is the problem: Imagine a file X that is to be shared between two domains as a disk. Let the first domain (vm1) have seclabel remembering turned on and the other (vm2) has it turned off. Assume that both domains will run under the same user, but the original owner of X is different (i.e. trying to access X without relabelling leads to EPERM).
How do we get into this situation ? Is this the case when we have a guest which was running before libvirt was upgraded, and then a new guest is launched ?
Yes, that's one of the possible scenarios. Another possible scenario would be (and this won't happen yet in reality beacuse NFS still does not implement XATTRs, but once they do we might hit it): two daemons and one shared NFS mount. One of the daemons has the feature enabled, the other has it disabled. But as I say, this won't happen with NFS today. But maybe there are some other shared filesystems which do implement XATTRs? Based on Wiki [1], OCFS2 does support it (even though I don't think there's anybody using it). 1: https://en.wikipedia.org/wiki/Extended_file_attributes Michal