Audiobuzz
f9f7c7c940
NTS proven end-to-end on comet-beacon-54 (chronyc authdata cookies > 0); these close the gaps the bench found so a clean build/serving run reaches that state without manual patching: - dispatcher (10-chrony-dhcp-ntp): fall back to resolv.conf search/domain when NM doesn't export DHCP4_DOMAIN_NAME on the firing event, so the NTS source is written reliably at boot (tonight it needed a manual dispatcher run). - STIG vs secure_ntp (P2, security): STIG's chronyd_specify_remote_server re-injects an UNAUTHENTICATED 'server 0.us.pool.ntp.mil maxpoll 16' AFTER the secure_ntp chrony step commented servers out -> a silent fallback that defeats NTS's DoS-only guarantee (host not fail-closed). Unselect chronyd_specify_remote_server + chronyd_or_ntpd_set_maxpoll in diskless-tailoring.xml, and re-strip any server/pool in 2c-STIG-postfix when secure_ntp=true. Documented: stig-deviations #17. - nts-cert.sh (P3): the container's chrony user (non-root) can't read a 0640 host-owned key -> NTS-KE TLS aborts ('non-properly terminated'). chown the key to the ntp container's chrony uid + keep 0640 (0644 works but chrony warns world-readable); 0644 fallback if the uid can't be found. Bench-verified 2026-07-11; docs updated in docs/ssh-host-certificate-design.md's sibling secure-ntp-design.md flow. F-03/P-18 stays open until a clean build shows chrony.conf has no plain server and authdata cookies>0 as the only source.
67 lines
2.9 KiB
Bash
67 lines
2.9 KiB
Bash
#!/bin/bash
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# NetworkManager dispatcher: point chrony at the fleet NTP server, learned from
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# DHCP at runtime (no FQDN baked into the image). Two modes, baked at build time:
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#
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# nts (secure_ntp=true, default): AUTHENTICATED time. Derive the server NAME
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# from the DHCP-provided domain as <PREFIX>.<domain> and write
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# `server NAME iburst nts`. chrony verifies the NTS-KE TLS cert against the
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# fleet CA (chrony.conf: ntstrustedcerts). Because the domain comes from
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# DHCP, a domain change needs only a new DHCP domain + reissued NTS cert —
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# no image rebuild. A DHCP/NTP/DNS spoofer can only DoS (no fleet-CA-signed
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# cert for the name it redirects to => NTS fails => no sync); it cannot
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# shift the clock. See docs/secure-ntp-design.md (F-03/P-18).
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#
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# dhcp (secure_ntp=false): LEGACY, UNAUTHENTICATED. Write the DHCP option-42
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# server IPs as plain `server <ip> iburst`. Lab/interop only.
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#
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# We use NetworkManager's internal DHCP (the network-manager dracut port); NM
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# exports the lease's domain as $DHCP4_DOMAIN_NAME (option 15) / $DHCP4_DOMAIN_SEARCH
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# (option 119) and NTP servers as $DHCP4_NTP_SERVERS (option 42). chrony.conf
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# carries `sourcedir /run/chrony-dhcp`, so writing <iface>.sources there and
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# reloading makes chronyd use them. The baked public pool is stripped (provisioner).
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#
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# Installed 0755 root:root. Lenient on purpose: a hiccup here must never break
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# networking. @NTP_MODE@/@NTP_PREFIX@ are substituted at build time.
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MODE="@NTP_MODE@" # nts | dhcp
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PREFIX="@NTP_PREFIX@" # nts: server name = <PREFIX>.<dhcp-domain>
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interface="$1"
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action="$2"
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case "$action" in
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up|dhcp4-change|reapply) ;;
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*) exit 0 ;;
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esac
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dir=/run/chrony-dhcp
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file="$dir/${interface}.sources"
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mkdir -p "$dir"
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if [ "$MODE" = nts ]; then
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# Prefer option 15 (domain-name); fall back to the first option-119 search
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# domain; finally fall back to resolv.conf's search/domain. NM does not export
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# $DHCP4_DOMAIN_NAME on every dispatcher event — at boot the source wasn't
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# written because the firing event carried no DHCP domain in env, yet
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# resolv.conf already had `search <domain>` (bench 2026-07-11). Reading it here
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# makes the NTS source get written reliably regardless of which event fires.
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domain="${DHCP4_DOMAIN_NAME:-}"
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[ -z "$domain" ] && domain="${DHCP4_DOMAIN_SEARCH%% *}"
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[ -z "$domain" ] && domain=$(awk '/^(search|domain)[[:space:]]/{print $2; exit}' /etc/resolv.conf 2>/dev/null)
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if [ -n "$domain" ]; then
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printf 'server %s.%s iburst nts\n' "$PREFIX" "$domain" > "$file"
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# Pick up the new source without restarting chronyd.
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chronyc reload sources >/dev/null 2>&1 || true
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fi
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else
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if [ -n "${DHCP4_NTP_SERVERS:-}" ]; then
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: > "$file"
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for s in $DHCP4_NTP_SERVERS; do
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printf 'server %s iburst\n' "$s" >> "$file"
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done
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chronyc reload sources >/dev/null 2>&1 || true
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fi
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fi
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exit 0
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