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Ian Jackson
9f72a8647b
We want to stop libxl trustingly reading information from the backend directory (since this is, of course, writeable by the backend, which might be a semi-trusted driver domain). In principle it is wrong in current libxl for anything to try to divine virtual device configuration from xenstore: the JSON domain config ought to supply that, and xenstore should only tell us which devices actually exist. However: Firstly, there are several existing places where configuration information is retrieved from xenstore rather than JSON. We do not want to reen gineer this in a security patch. Secondly, we want to make a security patch which can be backported to versions of libxl without the JSON configuration machinery. So we take the expedient approach of keeping a copy of the configuration somewhere we trust, namely /libxl. This is obviously fairly low-risk, although it does write significantly more keys in xenstore. In this patch we make this change in libxl__device_generic_add. This is responsible for actually writing the vast majority of device information to xenstore. There are a few loose ends which will be dealt with in a moment. Likewise, changes to readers to use the new location will appear in further patches. This is part of XSA-178. Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com>