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Bug 2223727 - Allow access to /dev/udmabuf (dma_device_t) from libvirt qemu (svirt_t)
Summary: Allow access to /dev/udmabuf (dma_device_t) from libvirt qemu (svirt_t)
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: selinux-policy
Version: 9.3
Hardware: Unspecified
OS: Linux
high
medium
Target Milestone: rc
: 9.3
Assignee: Nobody
QA Contact: Milos Malik
URL:
Whiteboard:
Depends On:
Blocks: 2032406
TreeView+ depends on / blocked
 
Reported: 2023-07-18 16:34 UTC by Jonathon Jongsma
Modified: 2023-11-07 11:24 UTC (History)
4 users (show)

Fixed In Version: selinux-policy-38.1.22-1.el9
Doc Type: Bug Fix
Doc Text:
Cause: In rhbz#2032406 is added support blob resources for virtio-vga/virtio-gpu device, which requires access to /dev/udmabuf. u-dma-buf is a Linux device driver that allocates contiguous memory blocks in the kernel space as DMA buffers and makes them available from the user space. Consequence: The missing allow rule causes SELinux denial Fix: Allow svirt to rw /dev/udmabuf Result: No SELinux denials.
Clone Of:
Environment:
Last Closed: 2023-11-07 08:52:40 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-162653 0 None None None 2023-07-18 16:36:55 UTC
Red Hat Product Errata RHBA-2023:6617 0 None None None 2023-11-07 08:53:04 UTC

Description Jonathon Jongsma 2023-07-18 16:34:08 UTC 
Bug 2032406 adds support for the virtio-gpu 'blob' feature to libvirt. This in turn requires qemu to access /dev/udmabuf. selinux prevents access to this device.

I get the following AVC messages when running in permissive mode:

time->Tue Jul 18 11:29:31 2023
type=PROCTITLE msg=audit(1689697771.305:3860): proctitle=2F7573722F6C6962657865632F71656D752D6B766D002D6E616D650067756573743D76647061626C6F636B2D746573742C64656275672D746872656164733D6F6E002D53002D6F626A656374007B22716F6D2D74797065223A22736563726574222C226964223A226D61737465724B657930222C22666F726D6174223A227261
type=SYSCALL msg=audit(1689697771.305:3860): arch=c000003e syscall=257 success=yes exit=33 a0=ffffff9c a1=55fe1ab9bda6 a2=2 a3=0 items=0 ppid=1 pid=267438 auid=21811 uid=107 gid=107 euid=107 suid=107 fsuid=107 egid=107 sgid=107 fsgid=107 tty=(none) ses=25 comm="qemu-kvm" exe="/usr/libexec/qemu-kvm" subj=unconfined_u:unconfined_r:svirt_t:s0:c190,c1016 key=(null)
type=AVC msg=audit(1689697771.305:3860): avc:  denied  { open } for  pid=267438 comm="qemu-kvm" path="/dev/udmabuf" dev="tmpfs" ino=6 scontext=unconfined_u:unconfined_r:svirt_t:s0:c190,c1016 tcontext=system_u:object_r:dma_device_t:s0 tclass=chr_file permissive=1
type=AVC msg=audit(1689697771.305:3860): avc:  denied  { read write } for  pid=267438 comm="qemu-kvm" name="udmabuf" dev="tmpfs" ino=6 scontext=unconfined_u:unconfined_r:svirt_t:s0:c190,c1016 tcontext=system_u:object_r:dma_device_t:s0 tclass=chr_file permissive=1
Comment 1 Nikola Knazekova 2023-07-27 17:36:02 UTC 
Hi Jonathon,

here is PR with the fix: https://github.com/fedora-selinux/selinux-policy/pull/1804
Comment 11 errata-xmlrpc 2023-11-07 08:52:40 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (selinux-policy bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:6617
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