1#!/bin/bash
2# Copyright 2021 Google LLC
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#      http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15
16[[ -n ${gbmc_br_gw_src_lib-} ]] && return
17
18# shellcheck source=meta-google/recipes-google/networking/network-sh/lib.sh
19source /usr/share/network/lib.sh || exit
20
21gbmc_br_gw_src_ip_stateful=
22gbmc_br_gw_src_ip_stateless=
23declare -A gbmc_br_gw_src_routes=()
24gbmc_br_gw_defgw=
25
26gbmc_br_set_router() {
27  local defgw=
28  local route
29  for route in "${!gbmc_br_gw_src_routes[@]}"; do
30    if [[ $route != *' dev gbmcbr '* ]]; then
31      defgw=1
32      break
33    fi
34  done
35  [[ $defgw == "$gbmc_br_gw_defgw" ]] && return
36  gbmc_br_gw_defgw="$defgw"
37
38  local files=(/run/systemd/network/{00,}-bmc-gbmcbr.network.d/50-defgw.conf)
39  if [[ -n $defgw ]]; then
40    local file
41    for file in "${files[@]}"; do
42      mkdir -p "$(dirname "$file")"
43      printf '[IPv6PrefixDelegation]\nRouterLifetimeSec=30\n' >"$file"
44    done
45  else
46    rm -f "${files[@]}"
47  fi
48
49  if [[ $(systemctl is-active systemd-networkd) != inactive ]]; then
50    networkctl reload && networkctl reconfigure gbmcbr
51  fi
52}
53
54gbmc_br_gw_src_update() {
55  local gbmc_br_gw_src_ip="${gbmc_br_gw_src_ip_stateful:-$gbmc_br_gw_src_ip_stateless}"
56  [[ -n $gbmc_br_gw_src_ip ]] || return
57
58  local route
59  for route in "${!gbmc_br_gw_src_routes[@]}"; do
60    [[ $route != *" src $gbmc_br_gw_src_ip "* ]] || continue
61    echo "gBMC Bridge Updating GW source [$gbmc_br_gw_src_ip]: $route" >&2
62    # shellcheck disable=SC2086
63    ip route change $route src "$gbmc_br_gw_src_ip" && \
64      unset 'gbmc_br_gw_src_routes[$route]'
65  done
66}
67
68gbmc_br_gw_src_hook() {
69  # We only want to match default gateway routes that are dynamic
70  # (have an expiration time). These will be updated with our preferred
71  # source.
72  # shellcheck disable=SC2154
73  if [[ $change == route && $route == 'default '*':'* ]]; then
74    if [[ $route =~ ^(.*)( +expires +[^ ]+)(.*)$ ]]; then
75      route="${BASH_REMATCH[1]}${BASH_REMATCH[3]}"
76    fi
77    if [[ $action == add && -z ${gbmc_br_gw_src_routes["$route"]} ]]; then
78      gbmc_br_gw_src_routes["$route"]=1
79      gbmc_br_gw_src_update
80      gbmc_br_set_router
81    elif [[ $action == del && -n "${gbmc_br_gw_src_routes["$route"]}" ]]; then
82      unset 'gbmc_br_gw_src_routes[$route]'
83      gbmc_br_gw_src_update
84      gbmc_br_set_router
85    fi
86  # Match only global IP addresses on the bridge that match the BMC stateless
87  # prefix (<mpfx>:fd00:). So 2002:af4:3480:2248:fd00:6345:3069:9186 would be
88  # matched as the preferred source IP for outoging traffic.
89  elif [[ $change == addr && $intf == gbmcbr && $scope == global ]] &&
90       [[ $fam == inet6 && $flags != *tentative* ]]; then
91    local ip_bytes=()
92    if ! ip_to_bytes ip_bytes "$ip"; then
93      echo "gBMC Bridge Ensure RA Invalid IP: $ip" >&2
94      return 1
95    fi
96    # Ignore ULAs and non-gBMC addresses
97    if (( ip_bytes[0] & 0xfe == 0xfc || ip_bytes[8] != 0xfd )); then
98      return 0
99    fi
100    if (( ip_bytes[9] != 0 )); then
101      local -n gbmc_br_gw_src_ip=gbmc_br_gw_src_ip_stateful
102    else
103      local -n gbmc_br_gw_src_ip=gbmc_br_gw_src_ip_stateless
104    fi
105    if [[ $action == add && $ip != "$gbmc_br_gw_src_ip" ]]; then
106      gbmc_br_gw_src_ip="$ip"
107      gbmc_br_gw_src_update
108    fi
109    if [[ $action == del && $ip == "$gbmc_br_gw_src_ip" ]]; then
110      gbmc_br_gw_src_ip=
111    fi
112  fi
113}
114
115GBMC_IP_MONITOR_HOOKS+=(gbmc_br_gw_src_hook)
116
117gbmc_br_gw_src_lib=1
118