nftables-1.0.4-3.el9

* Fri Nov 25 2022 Phil Sutter <psutter@redhat.com> [1.0.4-3.el9]
- Prevent port-shadow attacks in sample nat config (Phil Sutter) [2061940]
Resolves: rhbz#2061940

nat.nft

@@ -18,13 +18,21 @@ table ip nftables_svc {
 		elements = { 192.168.122.0/24 }
 	}
 
+	# force port randomization for non-locally originated connections using
+	# suspicious port values to prevent port-shadow attacks, i.e.
+	# accidental matching of new inbound connections vs. existing ones
+	chain do_masquerade {
+		meta iif > 0 th sport < 16384 th dport >= 32768 masquerade random
+		masquerade
+	}
+
 	# base-chain to manipulate conntrack in postrouting,
 	# will see packets for new or related traffic only
 	chain POSTROUTING {
 		type nat hook postrouting priority srcnat + 20
 		policy accept
 
-		iifname @masq_interfaces oifname != @masq_interfaces masquerade
-		ip saddr @masq_ips masquerade
+		iifname @masq_interfaces oifname != @masq_interfaces jump do_masquerade
+		ip saddr @masq_ips jump do_masquerade
 	}
 }

nftables.spec

@@ -1,5 +1,5 @@
 %define rpmversion 1.0.4
-%define specrelease 2
+%define specrelease 3
 
 Name:           nftables
 Version:        %{rpmversion}
@@ -131,6 +131,9 @@ sed -i -e 's/\(sofile=\)".*"/\1"'$sofile'"/' \
 %{python3_sitelib}/nftables/
 
 %changelog
+* Fri Nov 25 2022 Phil Sutter <psutter@redhat.com> [1.0.4-3.el9]
+- Prevent port-shadow attacks in sample nat config (Phil Sutter) [2061940]
+
 * Fri Jun 24 2022 Phil Sutter <psutter@redhat.com> [1.0.4-2.el9]
 - intervals: Do not sort cached set elements over and over again (Phil Sutter) [1917398]
 - intervals: do not empty cache for maps (Phil Sutter) [1917398]