Fix subnet protection for non-full network states (eg. limited, etc.) (…

…#419)

tailscale/rootfs/command/with-contenv-merge

@@ -0,0 +1,14 @@
+#!/command/execlineb -S0
+
+ifelse
+{
+  importas -D 0 S6_KEEP_ENV S6_KEEP_ENV
+  eltest 0${S6_KEEP_ENV} -eq 0
+}
+{
+  s6-envdir -Lfn -- /run/s6/container_environment
+  exec
+  $@
+}
+
+$@

tailscale/rootfs/etc/NetworkManager/dispatcher.d/protect-subnets

@@ -0,0 +1,22 @@
+#!/command/with-contenv-merge bashio
+# shellcheck shell=bash
+# The shebang 'with-contenv-merge' above is identical with 'with-contenv', but doesn't clear the current environment containing the dispatcher variables
+
+case "${NM_DISPATCHER_ACTION}" in
+  up|down|dhcp4-change|dhcp6-change)
+    bashio::log.info "Handling Network Manager action ${DEVICE_IP_IFACE-} ${NM_DISPATCHER_ACTION}"
+    unprotect-subnet-routes
+    if ! protect-subnet-routes; then
+      # Better stop add-on than risking losing all network connections
+      bashio::log.error "Failed to protect subnet routes. Halting add-on to prevent network loss."
+      echo -n 1 > /run/s6-linux-init-container-results/exitcode
+      exec /run/s6/basedir/bin/halt
+    fi
+    ;;
+  connectivity-change)
+    bashio::log.debug "Unhandled Network Manager action ${NM_DISPATCHER_ACTION} ${CONNECTIVITY_STATE-}"
+    ;;
+  *)
+    bashio::log.debug "Unhandled Network Manager action ${DEVICE_IP_IFACE-} ${NM_DISPATCHER_ACTION}"
+    ;;
+esac

tailscale/rootfs/usr/bin/protect-subnet-routes

@@ -4,19 +4,22 @@
 # In case of non userspace networking,
 # add local subnets to ip rules with higher priority than Tailscale's routing
 # ==============================================================================
+readonly PROTECTION_RULE_PRIORITY=5000
 
 declare -a routes=()
 declare route family
 declare response
 declare wait_counter=0
 
-if bashio::config.false "userspace_networking"; then
+if bashio::config.false "userspace_networking" && \
+  (! bashio::config.has_value "accept_routes" || bashio::config.true "accept_routes")
+then
   # If it is called after network configuration is changed, we need to drop cached network info
   bashio::cache.flush_all
   # It is possible to get "ERROR: Got unexpected response from the API: System is not ready with state: setup"
-  # So we wait a little
+  # So we wait a little, 60*5s = 300s = 5m
   while ! bashio::api.supervisor GET "/addons/self/options/config" false &> /dev/null; do
-    if (( wait_counter++ == 18 )); then
+    if (( wait_counter++ == 60 )); then
       bashio::log.error "Supervisor is unreachable"
       bashio::exit.nok
     fi
@@ -28,24 +31,31 @@ if bashio::config.false "userspace_networking"; then
   fi
 
   readarray -t routes < <(subnet-routes local)
-  if (( 0 < ${#routes[@]} )); then
-    bashio::log.info "Adding local subnets to ip rules with higher priority than Tailscale's routing,"
-    bashio::log.info "to prevent routing local subnets if the same subnet is routed within your tailnet."
-  fi
-  for route in "${routes[@]}"; do
-    if [[ "${route}" =~ .*:.* ]]; then
-      family="-6"
-    else
-      family="-4"
-    fi
-    bashio::log.info "  Adding route ${route} to ip rules"
-    if ! response=$(ip "${family}" rule add to "${route}" priority 5000 table main 2>&1); then
-      if [[ "${response}" != "RTNETLINK answers: File exists" ]]; then
-        echo "${response}"
-        bashio::exit.nok
+  bashio::log.info "Adding local subnets to ip rules with higher priority than Tailscale's routing,"
+  bashio::log.info "to prevent routing local subnets if the same subnet is routed within your tailnet."
+  if (( 0 == ${#routes[@]} )); then
+    # Do not remote this warning, usually this is superfluous,
+    # but I've run into situation where Supervisor needed a restart to return valid interface address data
+    # (that seems to be a hard to reproduce bug, better have some log in the future than not.)
+    # See: https://github.com/home-assistant/supervisor/issues/5361
+    bashio::log.warning "  There are no local subnets to protect!"
+    bashio::log.warning "  Maybe this is a temporary situation due to configuration change underway."
+  else
+    for route in "${routes[@]}"; do
+      if [[ "${route}" =~ .*:.* ]]; then
+        family="-6"
       else
-        bashio::log.notice "  Route ${route} is already added to ip rules"
+        family="-4"
       fi
-    fi
-  done
+      bashio::log.info "  Adding route ${route} to ip rules"
+      if ! response=$(ip "${family}" rule add to "${route}" priority ${PROTECTION_RULE_PRIORITY} table main 2>&1); then
+        if [[ "${response}" != "RTNETLINK answers: File exists" ]]; then
+          echo "${response}"
+          bashio::exit.nok
+        else
+          bashio::log.notice "  Route ${route} is already added to ip rules"
+        fi
+      fi
+    done
+  fi
 fi

tailscale/rootfs/usr/bin/subnet-routes

@@ -15,7 +15,7 @@ function appendarray() {
   readarray -t -O "${#array[@]}" array
 }
 
-if ! [[ $1 =~ ^(local|advertised)$ ]]; then
+if ! [[ "${1-}" =~ ^(local|advertised)$ ]]; then
   echo "Usage: subnet-routes local|advertised" 1>&2
   exit 1
 fi

tailscale/rootfs/usr/bin/unprotect-subnet-routes

@@ -4,14 +4,17 @@
 # In case of non userspace networking,
 # remove local subnets from ip rules
 # ==============================================================================
+readonly PROTECTION_RULE_PRIORITY=5000
 
 declare -a routes=()
 declare route family
 
-if bashio::config.false "userspace_networking"; then
+if bashio::config.false "userspace_networking" && \
+  (! bashio::config.has_value "accept_routes" || bashio::config.true "accept_routes")
+then
   readarray -t routes < <( \
     { ip -4 rule list; ip -6 rule list; } \
-    | { grep -E '^5000:' || true ;} \
+    | { grep -E "^${PROTECTION_RULE_PRIORITY}:" || true ;} \
     | sed -nr 's/^\d+:\s+from all to ([^\s]+) lookup main$/\1/p')
   for route in "${routes[@]}"; do
     bashio::log.info "Removing route ${route} from ip rules"