meta-google: gbmc-bridge: Recognize public addresses internally

We want to be able to categorize public addresses being used for
internal traffic, and allow them to access internal services.

Change-Id: I1f4b8eaa329954f330c3052c0c789b8e5e3b4662
Signed-off-by: William A. Kennington III <wak@google.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh
new file mode 100644
index 000000000..2099185e8
--- /dev/null
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-nft.sh
@@ -0,0 +1,63 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+[ -z "${gbmc_br_nft_lib-}" ] || return
+
+gbmc_br_nft_init=
+gbmc_br_nft_pfx=
+
+gbmc_br_nft_update() {
+  printf 'gBMC Bridge input firewall for %s\n' \
+    "${gbmc_br_nft_pfx:-(deleted)}" >&2
+
+  local contents=
+  contents+='table inet filter {'$'\n'
+  contents+='    chain gbmc_br_int_input {'$'\n'
+  if [ -n "${gbmc_br_nft_pfx-}" ]; then
+    contents+="        ip6 saddr $gbmc_br_nft_pfx"
+    contents+=" ip6 daddr $gbmc_br_nft_pfx accept"$'\n'
+  fi
+  contents+='    }'$'\n'
+  contents+='}'$'\n'
+
+  local rfile=/run/nftables/40-gbmc-br-int.rules
+  mkdir -p -m 755 "$(dirname "$rfile")"
+  printf '%s' "$contents" >"$rfile"
+
+  echo 'Restarting nftables' >&2
+  systemctl reset-failed nftables
+  systemctl --no-block restart nftables
+}
+
+gbmc_br_nft_hook() {
+  if [ "$change" = 'init' ]; then
+    gbmc_br_nft_init=1
+    gbmc_br_nft_update
+  # Match only global IP addresses on the bridge that match the BMC prefix
+  # (<mpfx>:fdxx:). So 2002:af4:3480:2248:fd02:6345:3069:9186 would become
+  # a 2002:af4:3480:2248:fd00/72 rule.
+  elif [ "$change" = 'addr' -a "$intf" = 'gbmcbr' -a "$scope" = 'global' ] &&
+       [[ "$fam" == 'inet6' && "$ip" =~ ^(([^:]+:){4}fd)[^:]{2}:.*$ ]] &&
+       [[ "$flags" != *tentative* ]]; then
+    pfx="${BASH_REMATCH[1]}00::/72"
+    if [ "$action" = "add" -a "$pfx" != "$gbmc_br_nft_pfx" ]; then
+      gbmc_br_nft_pfx="$pfx"
+      gbmc_br_nft_update
+    fi
+  fi
+}
+
+GBMC_IP_MONITOR_HOOKS+=(gbmc_br_nft_hook)
+
+gbmc_br_nft_lib=1