1# Copyright 2021 Google LLC
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#      http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14
15[ -z "${gbmc_br_nft_lib-}" ] || return
16
17source /usr/share/network/lib.sh || exit
18
19gbmc_br_nft_init=
20gbmc_br_nft_pfx=
21
22gbmc_br_nft_update() {
23  printf 'gBMC Bridge input firewall for %s\n' \
24    "${gbmc_br_nft_pfx:-(deleted)}" >&2
25
26  local contents=
27  contents+='table inet filter {'$'\n'
28  contents+='    chain gbmc_br_int_input {'$'\n'
29  if [ -n "${gbmc_br_nft_pfx-}" ]; then
30    contents+="        ip6 saddr $gbmc_br_nft_pfx"
31    contents+=" ip6 daddr $gbmc_br_nft_pfx accept"$'\n'
32  fi
33  contents+='    }'$'\n'
34  contents+='}'$'\n'
35
36  local rfile=/run/nftables/40-gbmc-br-int.rules
37  mkdir -p -m 755 "$(dirname "$rfile")"
38  printf '%s' "$contents" >"$rfile"
39
40  systemctl reset-failed nftables && systemctl --no-block reload-or-restart nftables || true
41}
42
43gbmc_br_nft_hook() {
44  if [ "$change" = 'init' ]; then
45    gbmc_br_nft_init=1
46    gbmc_br_nft_update
47  # Match only global IP addresses on the bridge that match the BMC prefix
48  # (<mpfx>:fdxx:). So 2002:af4:3480:2248:fd02:6345:3069:9186 would become
49  # a 2002:af4:3480:2248:fd00/76 rule.
50  elif [ "$change" = 'addr' -a "$intf" = 'gbmcbr' -a "$scope" = 'global' ] &&
51       [[ "$fam" == 'inet6' && "$flags" != *tentative* ]]; then
52    local ip_bytes=()
53    if ! ip_to_bytes ip_bytes "$ip"; then
54      echo "gBMC Bridge NFT Invalid IP: $ip" >&2
55      return 1
56    fi
57    if (( ip_bytes[8] != 0xfd )); then
58      return 0
59    fi
60    local i
61    for (( i=9; i<16; i++ )); do
62      ip_bytes[$i]=0
63    done
64    pfx="$(ip_bytes_to_str ip_bytes)/76"
65    if [ "$action" = "add" -a "$pfx" != "$gbmc_br_nft_pfx" ]; then
66      gbmc_br_nft_pfx="$pfx"
67      gbmc_br_nft_update
68    fi
69  fi
70}
71
72GBMC_IP_MONITOR_HOOKS+=(gbmc_br_nft_hook)
73
74gbmc_br_nft_lib=1
75