Project-2 baseline

worker-toolkit-potion-polyglot/task-shared/dns-jail-container.sh

@@ -76,7 +76,10 @@ dnsjail_apply() {
     drop_ours
     # cache-size=0: every lookup goes upstream, so a jailed container sees what an unjailed
     # one would rather than an answer this resolver decided to keep.
-    dnsmasq --no-resolv --no-hosts --listen-address=127.0.0.1 --bind-interfaces \
+    # -u root: dnsmasq 2.80 (buster and older bases) drops to "nobody" and calls capset to
+    # retain CAP_NET_ADMIN, which docker's default cap set does not grant -- so it exits and
+    # the jail fails open on every such image.
+    dnsmasq -u root --no-resolv --no-hosts --listen-address=127.0.0.1 --bind-interfaces \
             --cache-size=0 --pid-file="$STATE/dnsmasq.pid" --address=/#/ $srv \
             >/dev/null 2>>"$STATE/dnsmasq.err" || true
   fi