meta-google: gbmc-bridge: Assign stable addresses from RAs

We want BMCs to be able to discover their machine prefix and assign a
stable IPv6 based on that prefix combined with the MAC of the BMC.

Change-Id: I67b8c56f50ff3a970175abcb81b429ceb1258b69
Signed-off-by: William A. Kennington III <wak@google.com>

5 files changed, 138 insertions, 1 deletions

diff --git a/meta-google/recipes-google/networking/gbmc-bridge.bb b/meta-google/recipes-google/networking/gbmc-bridge.bb
index a4e7881ed..80a42bd17 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge.bb
+++ b/meta-google/recipes-google/networking/gbmc-bridge.bb
@@ -15,6 +15,9 @@ SRC_URI += " \
   file://ipmi.service.in \
   file://50-gbmc-br.rules \
   file://gbmc-br-ula.sh \
+  file://gbmc-br-from-ra.sh \
+  file://gbmc-br-ensure-ra.sh \
+  file://gbmc-br-ensure-ra.service \
   "
 
 FILES_${PN}_append = " \
@@ -25,11 +28,15 @@ FILES_${PN}_append = " \
   "
 
 RDEPENDS_${PN}_append = " \
+  bash \
   gbmc-ip-monitor \
   mstpd-mstpd \
   network-sh \
+  ndisc6-rdisc6 \
   "
 
+SYSTEMD_SERVICE_${PN} += "gbmc-br-ensure-ra.service"
+
 GBMC_BR_MAC_ADDR ?= ""
 
 # Generated via https://cd34.com/rfc4193/ based on a MAC from a machine I own
@@ -81,4 +88,10 @@ do_install() {
   mondir=${D}${datadir}/gbmc-ip-monitor
   install -d -m0755 "$mondir"
   install -m0644 ${WORKDIR}/gbmc-br-ula.sh "$mondir"/
+  install -m0644 ${WORKDIR}/gbmc-br-from-ra.sh "$mondir"/
+
+  install -d -m0755 ${D}${libexecdir}
+  install -m0755 ${WORKDIR}/gbmc-br-ensure-ra.sh ${D}${libexecdir}/
+  install -d -m0755 ${D}${systemd_system_unitdir}
+  install -m0755 ${WORKDIR}/gbmc-br-ensure-ra.service ${D}${systemd_system_unitdir}/
 }
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/-bmc-gbmcbr.network b/meta-google/recipes-google/networking/gbmc-bridge/-bmc-gbmcbr.network
index 18d208a3b..37aea6c1e 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge/-bmc-gbmcbr.network
+++ b/meta-google/recipes-google/networking/gbmc-bridge/-bmc-gbmcbr.network
@@ -2,7 +2,7 @@
 Name=gbmcbr
 [Network]
 DHCP=false
-IPv6AcceptRA=false
+IPv6AcceptRA=true
 LLMNR=true
 MulticastDNS=true
 LinkLocalAddressing=ipv6
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ensure-ra.service b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ensure-ra.service
new file mode 100644
index 000000000..7f97cea48
--- /dev/null
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ensure-ra.service
@@ -0,0 +1,5 @@
+[Service]
+ExecStart=/usr/libexec/gbmc-br-ensure-ra.sh
+
+[Install]
+WantedBy=multi-user.target
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ensure-ra.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ensure-ra.sh
new file mode 100644
index 000000000..60e33d89b
--- /dev/null
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-ensure-ra.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+# 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.
+
+# Every 30 seconds, send out an RA so that the kernel will receive a response.
+# This ensures that all BMCs (even ones that think they are routers) get updated
+# information from the other systems on the network.
+w=30
+while true; do
+  start=$SECONDS
+  rdisc6 -m gbmcbr -r 1 -w $(( w * 1000 )) >/dev/null 2>/dev/null
+  # If rdisc6 exits early we still want to wait the full `w` time before
+  # starting again.
+  (( timeout = start + w - SECONDS ))
+  sleep $(( timeout < 0 ? 0 : timeout ))
+done
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh
new file mode 100644
index 000000000..9a5586b8a
--- /dev/null
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-from-ra.sh
@@ -0,0 +1,92 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+[ -z "${gbmc_br_from_ra_lib-}" ] || return
+
+source /usr/share/network/lib.sh || exit
+
+gbmc_br_from_ra_init=
+gbmc_br_from_ra_mac=
+declare -A gbmc_br_from_ra_pfxs=()
+declare -A gbmc_br_from_ra_prev_addrs=()
+
+gbmc_br_from_ra_update() {
+  [ -n "$gbmc_br_from_ra_init" -a -n "$gbmc_br_from_ra_mac" ] || return
+
+  local pfx
+  for pfx in "${!gbmc_br_from_ra_pfxs[@]}"; do
+    local cidr
+    if ! cidr="$(ipv6_pfx_to_cidr "$pfx")"; then
+      unset 'gbmc_br_from_ra_pfxs[$pfx]'
+      continue
+    fi
+    if (( cidr == 80 )); then
+      local sfx
+      if ! sfx="$(mac_to_eui48 "$gbmc_br_from_ra_mac")"; then
+        unset 'gbmc_br_from_ra_pfxs[$pfx]'
+        continue
+      fi
+      local addr
+      addr="$(ipv6_pfx_concat "$pfx" "$sfx")"
+    else
+      continue
+    fi
+    local valid="${gbmc_br_from_ra_pfxs["$pfx"]}"
+    if (( valid > 0 )); then
+      if [ -z "${gbmc_br_from_ra_prev_addrs["$addr"]-}" ]; then
+        echo "gBMC Bridge RA Addr Add: $addr" >&2
+        gbmc_br_from_ra_prev_addrs["$addr"]=1
+      fi
+      ip addr replace "$addr" dev gbmcbr noprefixroute
+    else
+      if [ -n "${gbmc_br_from_ra_prev_addrs["$addr"]-}" ]; then
+        echo "gBMC Bridge RA Addr Del: $addr" >&2
+        unset 'gbmc_br_from_ra_prev_addrs[$addr]'
+      fi
+      ip addr del "$addr" dev gbmcbr
+      unset 'gbmc_br_from_ra_pfxs[$pfx]'
+    fi
+  done
+}
+
+gbmc_br_from_ra_hook() {
+  if [ "$change" = 'init' ]; then
+    gbmc_br_from_ra_init=1
+    gbmc_br_from_ra_update
+  elif [[ "$change" == 'route' && "$route" != *' via '* ]] &&
+       [[ "$route" =~ ^(.* dev gbmcbr proto ra .*)( +expires +([^ ]+)sec).*$ ]]; then
+    pfx="${route%% *}"
+    if [ "$action" = 'add' ]; then
+      gbmc_br_from_ra_pfxs["$pfx"]="${BASH_REMATCH[3]}"
+      gbmc_br_from_ra_update
+    elif [ "$action" = 'del' ]; then
+      gbmc_br_from_ra_pfxs["$pfx"]=0
+      gbmc_br_from_ra_update
+    fi
+  elif [ "$change" = 'link' -a "$intf" = 'gbmcbr' ]; then
+    rdisc6 -m gbmcbr -r 1 -w 100 >/dev/null 2>&1
+    if [ "$action" = 'add' -a "$mac" != "$gbmc_br_from_ra_mac" ]; then
+      gbmc_br_from_ra_mac="$mac"
+      gbmc_br_from_ra_update
+    fi
+    if [ "$action" = 'del' -a "$mac" = "$gbmc_br_from_ra_mac" ]; then
+      gbmc_br_from_ra_mac=
+      gbmc_br_from_ra_update
+    fi
+  fi
+}
+
+GBMC_IP_MONITOR_HOOKS+=(gbmc_br_from_ra_hook)
+
+gbmc_br_from_ra_lib=1