[libvirt] [Qemu-devel] [RFC PATCH 0/4] block: file descriptor passing using -filefd and getfd_file

[Kevin Wolf]

Am 21.05.2012 22:19, schrieb Corey Bryant:
> libvirt's sVirt security driver provides SELinux MAC isolation for
> Qemu guest processes and their corresponding image files.  In other
> words, sVirt uses SELinux to prevent a QEMU process from opening
> files that do not belong to it.
> 
> sVirt provides this support by labeling guests and resources with
> security labels that are stored in file system extended attributes.
> Some file systems, such as NFS, do not support the extended
> attribute security namespace, and therefore cannot support sVirt
> isolation.
> 
> A solution to this problem is to provide fd passing support, where
> libvirt opens files and passes file descriptors to QEMU.  This,
> along with SELinux policy to prevent QEMU from opening files, can
> provide image file isolation for NFS files.
> 
> This patch series adds the -filefd command-line option and the
> getfd_file monitor command.  This will enable libvirt to open a
> file and push the corresponding filename and file descriptor to
> QEMU.  When QEMU needs to "open" a file, it will first check if the
> file descriptor was passed by either of these methods before
> attempting to actually open the file.

I thought we decided to avoid making some file names magic, and instead
go for the obvious /dev/fd/42?

Kevin