diff --git a/internal/nftables/compiler.go b/internal/nftables/compiler.go index 47dc59d..199afb4 100644 --- a/internal/nftables/compiler.go +++ b/internal/nftables/compiler.go @@ -467,19 +467,24 @@ func (c *Compiler) compileOneRule(state *FirewallState, tag, srcSpec, dstSpec, p dports, sports config.PortSpec, action config.RuleAction, logLevel string, dnatDest, origDest string, fwZone string, section config.RuleSection) error { - for _, src := range c.zoneSpecs(srcSpec) { + isDNAT := action == config.RuleDNAT || action == config.RuleRedirect + srcs := c.zoneSpecs(srcSpec) + if isDNAT { + srcs = c.dnatSourceSpecs(srcSpec, fwZone) + } + for _, src := range srcs { for _, srcAddr := range splitAddrs(src.Addr) { - if action == config.RuleDNAT || action == config.RuleRedirect { + if isDNAT { if dnatSkipsIntrazone(srcSpec, src.Zone, dstSpec) { continue } - if err := c.compileDNATAccept(state, tag, src.Zone, srcAddr, dstSpec, proto, dports, sports, action, fwZone, section); err != nil { + if err := c.compileDNATAccept(state, tag+":accept", src.Zone, srcAddr, dstSpec, proto, dports, sports, action, fwZone, section); err != nil { return err } } for _, od := range splitAddrs(origDest) { - if action == config.RuleDNAT || action == config.RuleRedirect { - if err := c.compileDNATRule(state, tag, src.Zone, srcAddr, od, dstSpec, proto, dports, action, logLevel); err != nil { + if isDNAT { + if err := c.compileDNATRule(state, tag, src.Zone, srcAddr, od, dstSpec, proto, dports, sports, action, logLevel); err != nil { return err } continue @@ -503,12 +508,29 @@ func (c *Compiler) compileOneRule(state *FirewallState, tag, srcSpec, dstSpec, p return nil } -// dnatSkipsIntrazone mirrors shorewall: a zone list or all!x source never pairs a zone with itself unless marked "+". +// dnatSourceSpecs hooks DNAT per source zone like shorewall: all/any expand to every zone but fw (prerouting never sees fw traffic). +func (c *Compiler) dnatSourceSpecs(spec, fwZone string) []config.ZoneSpec { + zone, addr := splitZoneSpec(spec) + base, _, _ := strings.Cut(zone, "!") + if base = strings.TrimSuffix(base, "+"); base != "all" && base != "any" { + return c.zoneSpecs(spec) + } + var out []config.ZoneSpec + for _, z := range c.expandZoneRef(zone) { + if z != fwZone { + out = append(out, config.ZoneSpec{Zone: z, Addr: addr}) + } + } + return out +} + +// dnatSkipsIntrazone mirrors shorewall: a zone list or all/any source never pairs a zone with itself unless marked "+". func dnatSkipsIntrazone(srcSpec, srcZone, dstSpec string) bool { zones, _, _ := strings.Cut(srcSpec, ":") - wild := isZoneExclusion(srcSpec) || strings.Contains(zones, ",") + base, _, _ := strings.Cut(zones, "!") + wild := base == "all" || base == "any" || strings.Contains(base, ",") dstZone, _, _ := strings.Cut(dstSpec, ":") - return wild && !strings.Contains(zones, "+!") && srcZone == dstZone + return wild && srcZone == dstZone } // compileDNATAccept emits the filter ACCEPT implied by DNAT/REDIRECT (shorewall's DNAT-/REDIRECT- omit it) for the translated flow. @@ -639,7 +661,7 @@ func (c *Compiler) compileZonePair(state *FirewallState, tag, srcZone, srcAddr, } func (c *Compiler) compileDNATRule(state *FirewallState, tag, srcZone, srcAddr, origDest, dstSpec, proto string, - dports config.PortSpec, action config.RuleAction, logLevel string) error { + dports, sports config.PortSpec, action config.RuleAction, logLevel string) error { chain := "prerouting" parts := strings.SplitN(dstSpec, ":", 3) @@ -667,7 +689,7 @@ func (c *Compiler) compileDNATRule(state *FirewallState, tag, srcZone, srcAddr, } } - matches, err := l4Matches(proto, dports, nil) + matches, err := l4Matches(proto, dports, sports) if err != nil { return err } diff --git a/internal/nftables/compiler_test.go b/internal/nftables/compiler_test.go index 6a08203..0dfcbbb 100644 --- a/internal/nftables/compiler_test.go +++ b/internal/nftables/compiler_test.go @@ -1627,7 +1627,7 @@ func TestCompile_QueueRedirMatchKernelReadback(t *testing.T) { for _, rules := range state.Rules { for _, r := range rules { w, ok := want[r.Tag] - if !ok || r.Chain != "prerouting" && r.Tag == "rule:3" { + if !ok { continue } if got := r.Exprs[len(r.Exprs)-1]; !reflect.DeepEqual(got, w) { @@ -1943,6 +1943,18 @@ func TestCompile_CommaZoneLists(t *testing.T) { want: map[string][]string{"prerouting": {"iif=eth0", "iif=eth2"}, "forward": {"iif=eth0 oif=eth2 daddr=192.0.2.10", "iif=eth2 oif=eth2 daddr=192.0.2.10"}}, }, + { + name: "dnat all source expands per zone and skips fw and the target zone", + rule: config.Rule{Action: config.RuleDNAT, Source: "all", Dest: "svr:192.0.2.10", Proto: "tcp", DPort: config.PortSpec{"80"}}, + want: map[string][]string{"prerouting": {"iif=eth3", "iif=eth1", "iif=eth0"}, + "forward": {"iif=eth3 oif=eth2 daddr=192.0.2.10", "iif=eth1 oif=eth2 daddr=192.0.2.10", "iif=eth0 oif=eth2 daddr=192.0.2.10"}}, + }, + { + name: "dnat any+ source keeps the target zone", + rule: config.Rule{Action: config.RuleDNAT, Source: "any+", Dest: "svr:192.0.2.10", Proto: "tcp", DPort: config.PortSpec{"80"}}, + want: map[string][]string{"prerouting": {"iif=eth3", "iif=eth1", "iif=eth0", "iif=eth2"}, + "forward": {"iif=eth3 oif=eth2 daddr=192.0.2.10", "iif=eth1 oif=eth2 daddr=192.0.2.10", "iif=eth0 oif=eth2 daddr=192.0.2.10", "iif=eth2 oif=eth2 daddr=192.0.2.10"}}, + }, { name: "dnat to fw accepts in input", rule: config.Rule{Action: config.RuleDNAT, Source: "net", Dest: "fw:192.0.2.1", Proto: "tcp", DPort: config.PortSpec{"80"}}, @@ -2056,7 +2068,7 @@ func TestCompile_CommaZoneLists(t *testing.T) { got := map[string][]string{} for chain, rules := range state.Rules { for _, r := range rules { - if r.Tag == tag { + if r.Tag == tag || r.Tag == tag+":accept" { got[chain] = append(got[chain], describeRule(r)) } } @@ -2263,18 +2275,79 @@ func TestCompile_DNATImpliedAccept(t *testing.T) { if err != nil { t.Fatalf("Compile() error: %v", err) } - fwd := taggedRules(state, "forward", "rule:0") + fwd := taggedRules(state, "forward", "rule:0:accept") if len(fwd) != 1 { t.Fatalf("got %d forward accepts, want 1", len(fwd)) } want := append(append(append(append(append(matchIfaceName(true, "eth0"), matchIfaceName(false, "eth2")...), mustExprs(t)(matchDestCIDR("192.0.2.17"))...), mustExprs(t)(l4Exprs("tcp", "8080"))...), - matchCtBits(expr.CtKeySTATUS, ctStatusDNAT)...), &expr.Verdict{Kind: expr.VerdictAccept}) + dnatStatusExprs...), &expr.Verdict{Kind: expr.VerdictAccept}) if !reflect.DeepEqual(fwd[0].Exprs, want) { t.Errorf("forward accept = %#v, want %#v", fwd[0].Exprs, want) } } +// IPS_DST_NAT = 1<<5, hard-coded so a wrong ctStatusDNAT or ct key fails here. +var dnatStatusExprs = []expr.Any{ + &expr.Ct{Key: expr.CtKeySTATUS, Register: 1}, + &expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: binary.NativeEndian.AppendUint32(nil, 32), Xor: []byte{0, 0, 0, 0}}, + &expr.Cmp{Op: expr.CmpOpNeq, Register: 1, Data: []byte{0, 0, 0, 0}}, +} + +func TestCompile_DNATImpliedAcceptGetsNoRuleExtras(t *testing.T) { + compile := func(r config.Rule) *FirewallState { + state, err := NewCompiler(listCfg(func(c *config.Config) { + c.Zones["svr"] = config.Zone{Type: config.ZoneIP} + c.Interfaces = append(c.Interfaces, config.Interface{Zone: "svr", Interface: "eth2"}) + c.Rules = []config.Rule{r} + })).Compile() + if err != nil { + t.Fatalf("Compile() error: %v", err) + } + return state + } + plain := config.Rule{Action: config.RuleDNAT, Source: "net", Dest: "svr:192.0.2.17", Proto: "tcp", DPort: config.PortSpec{"80"}} + extras := plain + extras.RateLimit, extras.Mark, extras.User = "10/sec:5", "0x1", "root" + want, got := compile(plain), compile(extras) + if len(taggedRules(got, "forward", "rule:0:accept")) != 1 { + t.Fatalf("want one forward accept, got %v", got.Rules["forward"]) + } + if !reflect.DeepEqual(got.Rules, want.Rules) { + t.Errorf("ratelimit/mark/user changed the DNAT rules:\ngot %#v\nwant %#v", got.Rules, want.Rules) + } +} + +func TestCompile_DNATMatchesSport(t *testing.T) { + state, err := NewCompiler(listCfg(func(c *config.Config) { + c.Zones["svr"] = config.Zone{Type: config.ZoneIP} + c.Interfaces = append(c.Interfaces, config.Interface{Zone: "svr", Interface: "eth2"}) + c.Rules = []config.Rule{{Action: config.RuleDNAT, Source: "net", Dest: "svr:192.0.2.17", Proto: "tcp", + DPort: config.PortSpec{"80"}, SPort: config.PortSpec{"1024"}}} + })).Compile() + if err != nil { + t.Fatalf("Compile() error: %v", err) + } + m, err := l4Matches("tcp", config.PortSpec{"80"}, config.PortSpec{"1024"}) + if err != nil { + t.Fatal(err) + } + for _, r := range append(taggedRules(state, "prerouting", "rule:0"), taggedRules(state, "forward", "rule:0:accept")...) { + if !containsExprs(r.Exprs, m[0].exprs) { + t.Errorf("%s rule lacks the sport match: %#v", r.Chain, r.Exprs) + } + } +} + +func containsExprs(haystack, needle []expr.Any) bool { + for i := 0; i+len(needle) <= len(haystack); i++ { + if reflect.DeepEqual(haystack[i:i+len(needle)], needle) { + return true + } + } + return false +} + func mustExprs(t *testing.T) func([]expr.Any, error) []expr.Any { return func(e []expr.Any, err error) []expr.Any { t.Helper() @@ -2298,6 +2371,7 @@ func TestCompile_CommaZoneListLimitErrors(t *testing.T) { {Action: config.RuleAccept, Source: "net", Dest: "fw,lan", RateLimit: "10/sec:5"}, {Action: config.RuleAccept, Source: "net,lan", Dest: "fw", ConnLimit: "10"}, {Action: config.RuleAccept, Source: "net", Dest: "fw:192.0.2.1,198.51.100.1", RateLimit: "10/sec"}, + {Action: config.RuleDNAT, Source: "net,lan", Dest: "fw:192.0.2.1", RateLimit: "10/sec"}, } { t.Run(r.Source+">"+r.Dest, func(t *testing.T) { cfg := &config.Config{