checksums: materialize CHECKSUM_PARTIAL before pf so address-rewrite fixups operate on real values; new 06-rdr gate

module/pfsrc/pfk_hooks.c

@@ -140,6 +140,20 @@ pfk_pkt_work(struct work_struct *w)
 		orig_src = ip_hdr(pk->skb)->saddr;
 	}
 
+	/*
+	 * pf patches transport checksums incrementally when it rewrites an
+	 * address.  VM-to-VM traffic commonly arrives with an unmaterialized
+	 * checksum (CHECKSUM_PARTIAL carried over from the sender's offload),
+	 * so compute it in software first - otherwise pf's fixup adjusts a
+	 * placeholder and the peer drops the packet.
+	 */
+	if (pk->skb->ip_summed == CHECKSUM_PARTIAL &&
+	    skb_checksum_help(pk->skb)) {
+		kfree_skb(pk->skb);
+		kfree(pk);
+		return;
+	}
+
 	m = pfk_m_wrap_skb(pk->skb, pk->af);
 	if (!m) {
 		pfk_pkt_reinject(pk);	/* like "pf not consulted" */

tests/vm/06-rdr.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# M3 gate: rdr-to — destination/port redirect.
+#
+# Lab: the client connects to the firewall's own address 10.0.1.1:8080; pf
+# redirects it to the server (10.0.2.20:80, busybox httpd).  This exercises
+# the inbound translation *and* the re-route of a packet whose destination pf
+# rewrote (the packet is no longer local to the firewall).
+set -uo pipefail; cd "$(dirname "$0")"; . ./lib.sh
+
+pf0 'insmod /opt/pf/pf.ko 2>/dev/null || insmod /tmp/pf.ko; true'
+pf0 '/opt/pf/pfctl -e; /opt/pf/pfctl -f /dev/null' >/dev/null
+
+# a tiny responder on srv:80 (base64-encoded so it survives the two ssh hops
+# without nested quoting problems; detached so ssh returns)
+LOOP=$(printf 'while :; do nc -l -p 80 < /tmp/resp.txt >/dev/null 2>&1; done\n' | base64 | tr -d '\n')
+# NOTE: never pkill -f a pattern that also appears in this very command line -
+# it kills the invoking shell.  Use a pidfile and check the listening socket.
+srv "echo PF-RDR-OK > /tmp/resp.txt; echo $LOOP | base64 -d > /tmp/loop.sh; [ -f /tmp/loop.pid ] && kill \$(cat /tmp/loop.pid) 2>/dev/null; pkill nc 2>/dev/null; setsid sh /tmp/loop.sh >/dev/null 2>&1 </dev/null & echo \$! > /tmp/loop.pid; sleep 1; netstat -lnt 2>/dev/null | grep -q ':80 ' && echo RESPONDER_UP" | grep -q RESPONDER_UP && ok "responder up on srv:80" || bad "responder start"
+
+cat > /tmp/g06.conf <<C
+pass in quick proto tcp from 10.0.1.0/24 to 10.0.1.1 port 8080 rdr-to $SRV_IP port 80 keep state
+pass out quick proto tcp keep state
+C
+pfload /tmp/g06.conf || { bad "rdr rule load"; finish; }
+pf0 '/opt/pf/pfctl -sr' | grep -q 'rdr-to' && ok "rdr rule listed" || bad "rdr not listed"
+
+# the client talks to the firewall's address; pf redirects to srv:80
+RESP=$(cli 'printf "GET / HTTP/1.0\r\n\r\n" | nc -w3 10.0.1.1 8080' 2>/dev/null)
+if echo "$RESP" | grep -q 'PF-RDR-OK'; then
+	ok "redirect delivered the response"
+else
+	bad "no redirected response"
+	printf '%s\n' "$RESP" | head -4 | sed 's/^/    /'
+fi
+
+# the state must show the translated tuple (server:80 with the original in parens)
+pf0 '/opt/pf/pfctl -ss' | grep -E "$SRV_IP:80 .*$CLI_IP" >/dev/null && ok "state shows the translation" || bad "no translated state"
+
+# the reply path must survive the un-redirect
+pf0 '/opt/pf/pfctl -s info' | grep -qiE 'match' && ok "counters readable" || bad "counters"
+
+srv '[ -f /tmp/loop.pid ] && kill $(cat /tmp/loop.pid) 2>/dev/null; pkill nc 2>/dev/null; true' >/dev/null
+pf0 '/opt/pf/pfctl -d' >/dev/null
+finish