[libvirt] [PATCH v2 2/2] security: aa-helper: generate more rules for gl devices

[Christian Ehrhardt]

Change fb01e1a44 "virt-aa-helper: generate rules for gl enabled
graphics devices" implemented the detection for gl enabled
devices in virt-aa-helper. But further testing showed
that it will need much more access for the full gl stack
to work.

Upstream apparmor just recently split those things out and now
has two related abstractions at
https://gitlab.com/apparmor/apparmor/blob/master:
- dri-common at /profiles/apparmor.d/abstractions/dri-common
- mesa: at /profiles/apparmor.d/abstractions/mesa

If would be great to just include that for the majority of
rules, but they are not yet in any distribution so we need
to add rules inspired by them based on the testing that we
can do.

Furthermore qemu with opengl will also probe the backing device
of the rendernode for attributes which should be safe as
read-only wildcard rules.

Fixes: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1815452

Signed-off-by: Christian Ehrhardt <christian.ehrhardt at canonical.com>
---
 src/security/virt-aa-helper.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/security/virt-aa-helper.c b/src/security/virt-aa-helper.c
index 8e22e9978a..784ee49e61 100644
--- a/src/security/virt-aa-helper.c
+++ b/src/security/virt-aa-helper.c
@@ -937,7 +937,7 @@ get_files(vahControl * ctl)
     size_t i;
     char *uuid;
     char uuidstr[VIR_UUID_STRING_BUFLEN];
-    bool needsVfio = false, needsvhost = false;
+    bool needsVfio = false, needsvhost = false, needsgl = false;
 
     /* verify uuid is same as what we were given on the command line */
     virUUIDFormat(ctl->def->uuid, uuidstr);
@@ -1065,9 +1065,11 @@ get_files(vahControl * ctl)
 
         if (rendernode) {
             vah_add_file(&buf, rendernode, "rw");
+            needsgl = true;
         } else {
             if (virDomainGraphicsNeedsAutoRenderNode(graphics)) {
                 char *defaultRenderNode = virHostGetDRMRenderNode();
+                needsgl = true;
 
                 if (defaultRenderNode) {
                     vah_add_file(&buf, defaultRenderNode, "rw");
@@ -1267,6 +1269,23 @@ get_files(vahControl * ctl)
         virBufferAddLit(&buf, "  \"/dev/vfio/vfio\" rw,\n");
         virBufferAddLit(&buf, "  \"/dev/vfio/[0-9]*\" rw,\n");
     }
+    if (needsgl) {
+        /* if using gl all sorts of further dri related paths will be needed */
+        virBufferAddLit(&buf, "  # DRI/Mesa/(e)GL config and driver paths\n");
+        virBufferAddLit(&buf, "  \"/usr/lib{,32,64}/dri/**.so\" mr,\n");
+        virBufferAddLit(&buf, "  \"/usr/lib/@{multiarch}/dri/**.so\" mr,\n");
+        virBufferAddLit(&buf, "  \"/usr/lib/fglrx/dri/**.so\" mr,\n");
+        virBufferAddLit(&buf, "  \"/etc/drirc\" r,\n");
+        virBufferAddLit(&buf, "  \"/usr/share/drirc.d/{,*.conf}\" r,\n");
+        virBufferAddLit(&buf, "  \"/etc/glvnd/egl_vendor.d/{,*}\" r,\n");
+        virBufferAddLit(&buf, "  \"/usr/share/glvnd/egl_vendor.d/{,*}\" r,\n");
+        virBufferAddLit(&buf, "  # Probe DRI device attributes\n");
+        virBufferAddLit(&buf, "  \"/dev/dri/\" r,\n");
+        virBufferAddLit(&buf, "  \"/sys/devices/*/*/{uevent,vendor,device,subsystem_vendor,subsystem_device}\" r,\n");
+        virBufferAddLit(&buf, "  \"/sys/devices/*/*/drm/*/{uevent,vendor,device,subsystem_vendor,subsystem_device}\" r,\n");
+        virBufferAddLit(&buf, "  # dri libs will trigger that, but t is not requited and DAC would deny it anyway\n");
+        virBufferAddLit(&buf, "  deny \"/var/lib/libvirt/.cache/\" w,\n");
+    }
 
     if (ctl->newfile)
         if (vah_add_file(&buf, ctl->newfile, "rwk") != 0)
-- 
2.17.1