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Alex Williamson d3334471c3 vfio/type1: Limit DMA mappings per container 
commit 492855939b upstream.

Memory backed DMA mappings are accounted against a user's locked
memory limit, including multiple mappings of the same memory.  This
accounting bounds the number of such mappings that a user can create.
However, DMA mappings that are not backed by memory, such as DMA
mappings of device MMIO via mmaps, do not make use of page pinning
and therefore do not count against the user's locked memory limit.
These mappings still consume memory, but the memory is not well
associated to the process for the purpose of oom killing a task.

To add bounding on this use case, we introduce a limit to the total
number of concurrent DMA mappings that a user is allowed to create.
This limit is exposed as a tunable module option where the default
value of 64K is expected to be well in excess of any reasonable use
case (a large virtual machine configuration would typically only make
use of tens of concurrent mappings).

This fixes CVE-2019-3882.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
[bwh: Backported to 3.16:
 - Add the out_unlock label in vfio_dma_do_map()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
History 2019-05-02 21:42:03 +01:00
..
pci vfio/pci: Fix integer overflows, bitmask check 2016-11-20 01:17:37 +00:00
Kconfig vfio: always select ANON_INODES 2014-03-27 11:58:58 -06:00
Makefile powerpc/vfio: Implement IOMMU driver for VFIO 2013-06-20 16:55:14 +10:00
vfio.c vfio: New external user group/file match 2017-10-12 15:27:55 +01:00
vfio_iommu_spapr_tce.c powerpc/iommu: Update constant names to reflect their hardcoded page size 2013-12-30 14:17:06 +11:00
vfio_iommu_type1.c vfio/type1: Limit DMA mappings per container 2019-05-02 21:42:03 +01:00