Run profile through apparmor_parser before copying it

web/packages/teleterm/build_resources/linux/after-install.tpl

@@ -64,17 +64,31 @@ else
   fi
 fi
 
-APPARMOR_PROFILE_DEST="/etc/apparmor.d/teleport-connect"
+APPARMOR_PROFILE_SOURCE="$APP/resources/apparmor-profile"
+APPARMOR_PROFILE_TARGET="/etc/apparmor.d/teleport-connect"
 
 # Install apparmor profile.
-if [ -d "/etc/apparmor.d" ]; then
-  cp -f "$APP/resources/apparmor-profile" "$APPARMOR_PROFILE_DEST"
+# First check if the version of AppArmor running on the device supports our profile.
+# This is in order to keep backwards compatibility with Ubuntu 22.04 which does not support abi/4.0.
+# In that case, we just skip installing the profile since the app runs fine without it on 22.04.
+#
+# Those apparmor_parser flags are akin to performing a dry run of loading a profile.
+# https://wiki.debian.org/AppArmor/HowToUse#Dumping_profiles
+#
+# Unfortunately, at the moment AppArmor doesn't have a good story for backwards compatibility.
+# https://askubuntu.com/questions/1517272/writing-a-backwards-compatible-apparmor-profile
+if test -d "/etc/apparmor.d"; then
+  if apparmor_parser --skip-kernel-load --debug "$APPARMOR_PROFILE_SOURCE" > /dev/null 2>&1; then
+    cp -f "$APPARMOR_PROFILE_SOURCE" "$APPARMOR_PROFILE_TARGET"
 
-  if hash apparmor_parser 2>/dev/null; then
-    # Extra flags taken from dh_apparmor:
-    # > By using '-W -T' we ensure that any abstraction updates are also pulled in.
-    # https://wiki.debian.org/AppArmor/Contribute/FirstTimeProfileImport
-    apparmor_parser --replace --write-cache --skip-read-cache "$APPARMOR_PROFILE_DEST"
+    if hash apparmor_parser 2>/dev/null; then
+      # Extra flags taken from dh_apparmor:
+      # > By using '-W -T' we ensure that any abstraction updates are also pulled in.
+      # https://wiki.debian.org/AppArmor/Contribute/FirstTimeProfileImport
+      apparmor_parser --replace --write-cache --skip-read-cache "$APPARMOR_PROFILE_TARGET"
+    fi
+  else
+    echo "Skipping the installation of the AppArmor profile as this version of AppArmor does not seem to support the profile bundled with Teleport Connect."
   fi
 fi