fix(hostmatcher): block reserved IP ranges from external/private filters (#38039)

2026-08-08 01:59:14 +00:00 · 2026-06-10 10:03:36 +02:00
parent 4ba0a545f2
commit 920b3f8cb6
2 changed files with 114 additions and 4 deletions
@@ -159,3 +159,58 @@ func TestHostOrIPMatchesList(t *testing.T) {
 	}
 	test(cases)
 }
+
+// TestReservedRanges ensures special-purpose ranges that net.IP.IsPrivate misses are kept out of the
+// "external" allow-list (the default for webhook delivery and repository migrations) and folded into
+// the "private" block-list, so they cannot be used for SSRF to metadata/internal endpoints.
+func TestReservedRanges(t *testing.T) {
+	external := ParseHostMatchList("", "external")
+	private := ParseHostMatchList("", "private")
+
+	// legitimate public destinations: external, not private
+	for _, ip := range []string{"8.8.8.8", "1.1.1.1", "2001:4860:4860::8888", "1000::1"} {
+		addr := net.ParseIP(ip)
+		assert.Truef(t, external.MatchIPAddr(addr), "public ip %s should be external", ip)
+		assert.Falsef(t, private.MatchIPAddr(addr), "public ip %s should not be private", ip)
+	}
+
+	// RFC 1918 / RFC 4193 private ranges (now folded into privateIPNets instead of net.IP.IsPrivate):
+	// not external, blockable as private. Includes range edges to guard the CIDR boundaries.
+	for _, ip := range []string{
+		"10.0.0.0", "10.255.255.255", // 10.0.0.0/8
+		"172.16.0.0", "172.31.255.255", // 172.16.0.0/12
+		"192.168.0.0", "192.168.255.255", // 192.168.0.0/16
+		"fc00::", "fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff", // fc00::/7
+	} {
+		addr := net.ParseIP(ip)
+		assert.Falsef(t, external.MatchIPAddr(addr), "private ip %s must not be external", ip)
+		assert.Truef(t, private.MatchIPAddr(addr), "private ip %s should match private block-list", ip)
+	}
+
+	// 172.32.0.0 is just outside 172.16.0.0/12: a public destination, not private
+	if addr := net.ParseIP("172.32.0.0"); assert.NotNil(t, addr) {
+		assert.True(t, external.MatchIPAddr(addr), "172.32.0.0 should be external")
+		assert.False(t, private.MatchIPAddr(addr), "172.32.0.0 should not be private")
+	}
+
+	// reserved ranges that IsPrivate does not cover: not external, but blockable as private
+	for _, ip := range []string{
+		"100.64.0.1",         // CGNAT
+		"100.127.255.254",    // CGNAT
+		"168.63.129.16",      // Azure WireServer
+		"192.0.2.1",          // TEST-NET-1
+		"198.18.0.1",         // benchmarking
+		"198.51.100.1",       // TEST-NET-2
+		"203.0.113.1",        // TEST-NET-3
+		"192.88.99.1",        // 6to4 relay anycast
+		"64:ff9b::1",         // NAT64
+		"64:ff9b::a9fe:a9fe", // NAT64 embedding 169.254.169.254
+		"2001::1",            // Teredo
+		"2002::1",            // 6to4
+		"2001:db8::1",        // documentation
+	} {
+		addr := net.ParseIP(ip)
+		assert.Falsef(t, external.MatchIPAddr(addr), "reserved ip %s must not be external", ip)
+		assert.Truef(t, private.MatchIPAddr(addr), "reserved ip %s should match private block-list", ip)
+	}
+}