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security: do not remember/recall labels for VFIO

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Files inside /dev/vfio/ can't be opened more than once, meaning
that any subsequent open calls will fail. This behavior was
introduced in kernel v3.11, commit 6d6768c61b39.

When using the VFIO driver, we open a FD to /dev/vfio/N and
pass it to QEMU. If any other call attempt for the same
/dev/vfio/N happens while QEMU is still using the file, we are
unable to open it and QEMU will report -EBUSY. This can happen
if we hotplug a PCI hostdev that belongs to the same IOMMU group
of an existing domain hostdev.

The problem and solution is similar to what we already dealt
with for TPM in commit 4e95cdcbb3. This patch changes both
DAC and SELinux drivers to disable 'remember' for VFIO hostdevs
in virSecurityDACSetHostdevLabelHelper() and
virSecurityDACSetHostdevLabel(), and 'recall'
in virSecurityDACRestoreHostdevLabel() and
virSecuritySELinuxRestoreHostdevSubsysLabel().

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Daniel Henrique Barboza 2020-01-27 15:23:21 -03:00 committed by Michal Privoznik
parent 09804edd0a
commit dbf1f68410
2 changed files with 9 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
src/security/security_dac.c
View File

@ -1263,7 +1263,9 @@ virSecurityDACSetHostdevLabel(virSecurityManagerPtr mgr,
virPCIDeviceFree(pci);
return -1;
}
ret = virSecurityDACSetPCILabel(pci, vfioGroupDev, &cbdata);
ret = virSecurityDACSetHostdevLabelHelper(vfioGroupDev,
false,
&cbdata);
VIR_FREE(vfioGroupDev);
} else {
ret = virPCIDeviceFileIterate(pci,
@ -1430,7 +1432,8 @@ virSecurityDACRestoreHostdevLabel(virSecurityManagerPtr mgr,
virPCIDeviceFree(pci);
return -1;
}
ret = virSecurityDACRestorePCILabel(pci, vfioGroupDev, mgr);
ret = virSecurityDACRestoreFileLabelInternal(mgr, NULL,
vfioGroupDev, false);
VIR_FREE(vfioGroupDev);
} else {
ret = virPCIDeviceFileIterate(pci, virSecurityDACRestorePCILabel, mgr);

6
src/security/security_selinux.c
View File

@ -2118,7 +2118,9 @@ virSecuritySELinuxSetHostdevSubsysLabel(virSecurityManagerPtr mgr,
virPCIDeviceFree(pci);
return -1;
}
ret = virSecuritySELinuxSetPCILabel(pci, vfioGroupDev, &data);
ret = virSecuritySELinuxSetHostdevLabelHelper(vfioGroupDev,
false,
&data);
VIR_FREE(vfioGroupDev);
} else {
ret = virPCIDeviceFileIterate(pci, virSecuritySELinuxSetPCILabel, &data);
@ -2356,7 +2358,7 @@ virSecuritySELinuxRestoreHostdevSubsysLabel(virSecurityManagerPtr mgr,
virPCIDeviceFree(pci);
return -1;
}
ret = virSecuritySELinuxRestorePCILabel(pci, vfioGroupDev, mgr);
ret = virSecuritySELinuxRestoreFileLabel(mgr, vfioGroupDev, false);
VIR_FREE(vfioGroupDev);
} else {
ret = virPCIDeviceFileIterate(pci, virSecuritySELinuxRestorePCILabel, mgr);