Messages in this thread | | | Subject | Re: Security issues with local filesystem caching | From | Stephen Smalley <> | Date | Wed, 01 Nov 2006 12:45:34 -0500 |
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On Wed, 2006-11-01 at 10:58 -0500, Karl MacMillan wrote: > I suggested change instead of transition because, like most uses of > change, this was a manual relabel rather than automatic. Transition > probably makes more sense, though.
Yes, if we need it at all.
> This is all predicated on the notion that there is a need to have the > normal SELinux checks performed. Since this serves only as a sanity > check and doesn't add any real security the best option seems bypass, > but I guess that isn't an option.
"Bypass" in the sense of directly calling the inode ops rather than the vfs helpers is undesirable. "Bypass" in the sense of temporarily setting a task flag indicating that permission checking should be disabled for an internal access attempt seems ok.
> fssid seems like the wrong name, though it does match the DAC concept. > This is really more general impersonation of another domain by the > kernel and might have other uses.
NFS will want a fssid in order to have file access checks applied against the client process' SID if/when the client process' context becomes available. But it isn't really necessary here as far as I can see; the cachefiles module is not trying to act on behalf of a task, but instead is performing an internal access to local cache that should always succeed, and the usual permission checking for userspace is handled by the fs before cachefiles is called.
-- Stephen Smalley National Security Agency
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