virt-aa-helper: Fix AppArmor profile

Since

  commit 432faf25
  Author: Michal Privoznik <mprivozn@redhat.com>
  Date:   Tue Jul 2 19:49:51 2019 +0200

    virCommand: use procfs to learn opened FDs

    When spawning a child process, between fork() and exec() we close
    all file descriptors and keep only those the caller wants us to
    pass onto the child. The problem is how we do that. Currently, we
    get the limit of opened files and then iterate through each one
    of them and either close() it or make it survive exec(). This
    approach is suboptimal (although, not that much in default
    configurations where the limit is pretty low - 1024). We have
    /proc where we can learn what FDs we hold open and thus we can
    selectively close only those.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

  v5.5.0-173-g432faf25

programs using the virCommand APIs on Linux need read access to
/proc/self/fd, or they will fail like

  error : virCommandWait:2796 : internal error: Child process
  (LIBVIRT_LOG_OUTPUTS=3:stderr /usr/lib/libvirt/virt-aa-helper -c
   -u libvirt-b20e9a8e-091a-45e0-8823-537119e98bc6) unexpected exit
  status 1: libvirt:  error : cannot open directory '/proc/self/fd':
  Permission denied
  virt-aa-helper: error: apparmor_parser exited with error

Update the AppArmor profile for virt-aa-helper so that read access
to the relevant path is granted.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/security/apparmor/usr.lib.libvirt.virt-aa-helper

@@ -17,6 +17,10 @@ profile virt-aa-helper /usr/{lib,lib64}/libvirt/virt-aa-helper {
   owner @{PROC}/[0-9]*/status r,
   @{PROC}/filesystems r,
 
+  # Used when internally running another command (namely apparmor_parser)
+  @{PROC}/self/fd r,
+  @{PROC}/@{pid}/fd r,
+
   /etc/libnl-3/classid r,
 
   # for gl enabled graphics