ip6tables: move target-specific code to targets.go

This is purely moving code, no changes. netfilter.go is cluttered and targets.go
is a good place for this.

#3549

PiperOrigin-RevId: 325879965

2 files changed, 247 insertions, 240 deletions

diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go
index a9f0604ae..e91b0624c 100644
--- a/pkg/sentry/socket/netfilter/netfilter.go
+++ b/pkg/sentry/socket/netfilter/netfilter.go
@@ -32,15 +32,6 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
-// errorTargetName is used to mark targets as error targets. Error targets
-// shouldn't be reached - an error has occurred if we fall through to one.
-const errorTargetName = "ERROR"
-
-// redirectTargetName is used to mark targets as redirect targets. Redirect
-// targets should be reached for only NAT and Mangle tables. These targets will
-// change the destination port/destination IP for packets.
-const redirectTargetName = "REDIRECT"
-
 // enableLogging controls whether to log the (de)serialization of netfilter
 // structs between userspace and netstack. These logs are useful when
 // developing iptables, but can pollute sentry logs otherwise.
@@ -202,130 +193,6 @@ func convertNetstackToBinary(stack *stack.Stack, tablename linux.TableName) (lin
 	return entries, info, nil
 }
 
-func marshalTarget(target stack.Target) []byte {
-	switch tg := target.(type) {
-	case stack.AcceptTarget:
-		return marshalStandardTarget(stack.RuleAccept)
-	case stack.DropTarget:
-		return marshalStandardTarget(stack.RuleDrop)
-	case stack.ErrorTarget:
-		return marshalErrorTarget(errorTargetName)
-	case stack.UserChainTarget:
-		return marshalErrorTarget(tg.Name)
-	case stack.ReturnTarget:
-		return marshalStandardTarget(stack.RuleReturn)
-	case stack.RedirectTarget:
-		return marshalRedirectTarget(tg)
-	case JumpTarget:
-		return marshalJumpTarget(tg)
-	default:
-		panic(fmt.Errorf("unknown target of type %T", target))
-	}
-}
-
-func marshalStandardTarget(verdict stack.RuleVerdict) []byte {
-	nflog("convert to binary: marshalling standard target")
-
-	// The target's name will be the empty string.
-	target := linux.XTStandardTarget{
-		Target: linux.XTEntryTarget{
-			TargetSize: linux.SizeOfXTStandardTarget,
-		},
-		Verdict: translateFromStandardVerdict(verdict),
-	}
-
-	ret := make([]byte, 0, linux.SizeOfXTStandardTarget)
-	return binary.Marshal(ret, usermem.ByteOrder, target)
-}
-
-func marshalErrorTarget(errorName string) []byte {
-	// This is an error target named error
-	target := linux.XTErrorTarget{
-		Target: linux.XTEntryTarget{
-			TargetSize: linux.SizeOfXTErrorTarget,
-		},
-	}
-	copy(target.Name[:], errorName)
-	copy(target.Target.Name[:], errorTargetName)
-
-	ret := make([]byte, 0, linux.SizeOfXTErrorTarget)
-	return binary.Marshal(ret, usermem.ByteOrder, target)
-}
-
-func marshalRedirectTarget(rt stack.RedirectTarget) []byte {
-	// This is a redirect target named redirect
-	target := linux.XTRedirectTarget{
-		Target: linux.XTEntryTarget{
-			TargetSize: linux.SizeOfXTRedirectTarget,
-		},
-	}
-	copy(target.Target.Name[:], redirectTargetName)
-
-	ret := make([]byte, 0, linux.SizeOfXTRedirectTarget)
-	target.NfRange.RangeSize = 1
-	if rt.RangeProtoSpecified {
-		target.NfRange.RangeIPV4.Flags |= linux.NF_NAT_RANGE_PROTO_SPECIFIED
-	}
-	// Convert port from little endian to big endian.
-	port := make([]byte, 2)
-	binary.LittleEndian.PutUint16(port, rt.MinPort)
-	target.NfRange.RangeIPV4.MinPort = binary.BigEndian.Uint16(port)
-	binary.LittleEndian.PutUint16(port, rt.MaxPort)
-	target.NfRange.RangeIPV4.MaxPort = binary.BigEndian.Uint16(port)
-	return binary.Marshal(ret, usermem.ByteOrder, target)
-}
-
-func marshalJumpTarget(jt JumpTarget) []byte {
-	nflog("convert to binary: marshalling jump target")
-
-	// The target's name will be the empty string.
-	target := linux.XTStandardTarget{
-		Target: linux.XTEntryTarget{
-			TargetSize: linux.SizeOfXTStandardTarget,
-		},
-		// Verdict is overloaded by the ABI. When positive, it holds
-		// the jump offset from the start of the table.
-		Verdict: int32(jt.Offset),
-	}
-
-	ret := make([]byte, 0, linux.SizeOfXTStandardTarget)
-	return binary.Marshal(ret, usermem.ByteOrder, target)
-}
-
-// translateFromStandardVerdict translates verdicts the same way as the iptables
-// tool.
-func translateFromStandardVerdict(verdict stack.RuleVerdict) int32 {
-	switch verdict {
-	case stack.RuleAccept:
-		return -linux.NF_ACCEPT - 1
-	case stack.RuleDrop:
-		return -linux.NF_DROP - 1
-	case stack.RuleReturn:
-		return linux.NF_RETURN
-	default:
-		// TODO(gvisor.dev/issue/170): Support Jump.
-		panic(fmt.Sprintf("unknown standard verdict: %d", verdict))
-	}
-}
-
-// translateToStandardTarget translates from the value in a
-// linux.XTStandardTarget to an stack.Verdict.
-func translateToStandardTarget(val int32) (stack.Target, error) {
-	// TODO(gvisor.dev/issue/170): Support other verdicts.
-	switch val {
-	case -linux.NF_ACCEPT - 1:
-		return stack.AcceptTarget{}, nil
-	case -linux.NF_DROP - 1:
-		return stack.DropTarget{}, nil
-	case -linux.NF_QUEUE - 1:
-		return nil, errors.New("unsupported iptables verdict QUEUE")
-	case linux.NF_RETURN:
-		return stack.ReturnTarget{}, nil
-	default:
-		return nil, fmt.Errorf("unknown iptables verdict %d", val)
-	}
-}
-
 // SetEntries sets iptables rules for a single table. See
 // net/ipv4/netfilter/ip_tables.c:translate_table for reference.
 func SetEntries(stk *stack.Stack, optVal []byte) *syserr.Error {
@@ -562,113 +429,6 @@ func parseMatchers(filter stack.IPHeaderFilter, optVal []byte) ([]stack.Matcher,
 	return matchers, nil
 }
 
-// parseTarget parses a target from optVal. optVal should contain only the
-// target.
-func parseTarget(filter stack.IPHeaderFilter, optVal []byte) (stack.Target, error) {
-	nflog("set entries: parsing target of size %d", len(optVal))
-	if len(optVal) < linux.SizeOfXTEntryTarget {
-		return nil, fmt.Errorf("optVal has insufficient size for entry target %d", len(optVal))
-	}
-	var target linux.XTEntryTarget
-	buf := optVal[:linux.SizeOfXTEntryTarget]
-	binary.Unmarshal(buf, usermem.ByteOrder, &target)
-	switch target.Name.String() {
-	case "":
-		// Standard target.
-		if len(optVal) != linux.SizeOfXTStandardTarget {
-			return nil, fmt.Errorf("optVal has wrong size for standard target %d", len(optVal))
-		}
-		var standardTarget linux.XTStandardTarget
-		buf = optVal[:linux.SizeOfXTStandardTarget]
-		binary.Unmarshal(buf, usermem.ByteOrder, &standardTarget)
-
-		if standardTarget.Verdict < 0 {
-			// A Verdict < 0 indicates a non-jump verdict.
-			return translateToStandardTarget(standardTarget.Verdict)
-		}
-		// A verdict >= 0 indicates a jump.
-		return JumpTarget{Offset: uint32(standardTarget.Verdict)}, nil
-
-	case errorTargetName:
-		// Error target.
-		if len(optVal) != linux.SizeOfXTErrorTarget {
-			return nil, fmt.Errorf("optVal has insufficient size for error target %d", len(optVal))
-		}
-		var errorTarget linux.XTErrorTarget
-		buf = optVal[:linux.SizeOfXTErrorTarget]
-		binary.Unmarshal(buf, usermem.ByteOrder, &errorTarget)
-
-		// Error targets are used in 2 cases:
-		// * An actual error case. These rules have an error
-		//   named errorTargetName. The last entry of the table
-		//   is usually an error case to catch any packets that
-		//   somehow fall through every rule.
-		// * To mark the start of a user defined chain. These
-		//   rules have an error with the name of the chain.
-		switch name := errorTarget.Name.String(); name {
-		case errorTargetName:
-			nflog("set entries: error target")
-			return stack.ErrorTarget{}, nil
-		default:
-			// User defined chain.
-			nflog("set entries: user-defined target %q", name)
-			return stack.UserChainTarget{Name: name}, nil
-		}
-
-	case redirectTargetName:
-		// Redirect target.
-		if len(optVal) < linux.SizeOfXTRedirectTarget {
-			return nil, fmt.Errorf("netfilter.SetEntries: optVal has insufficient size for redirect target %d", len(optVal))
-		}
-
-		if filter.Protocol != header.TCPProtocolNumber && filter.Protocol != header.UDPProtocolNumber {
-			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
-		}
-
-		var redirectTarget linux.XTRedirectTarget
-		buf = optVal[:linux.SizeOfXTRedirectTarget]
-		binary.Unmarshal(buf, usermem.ByteOrder, &redirectTarget)
-
-		// Copy linux.XTRedirectTarget to stack.RedirectTarget.
-		var target stack.RedirectTarget
-		nfRange := redirectTarget.NfRange
-
-		// RangeSize should be 1.
-		if nfRange.RangeSize != 1 {
-			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
-		}
-
-		// TODO(gvisor.dev/issue/170): Check if the flags are valid.
-		// Also check if we need to map ports or IP.
-		// For now, redirect target only supports destination port change.
-		// Port range and IP range are not supported yet.
-		if nfRange.RangeIPV4.Flags&linux.NF_NAT_RANGE_PROTO_SPECIFIED == 0 {
-			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
-		}
-		target.RangeProtoSpecified = true
-
-		target.MinIP = tcpip.Address(nfRange.RangeIPV4.MinIP[:])
-		target.MaxIP = tcpip.Address(nfRange.RangeIPV4.MaxIP[:])
-
-		// TODO(gvisor.dev/issue/170): Port range is not supported yet.
-		if nfRange.RangeIPV4.MinPort != nfRange.RangeIPV4.MaxPort {
-			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
-		}
-
-		// Convert port from big endian to little endian.
-		port := make([]byte, 2)
-		binary.BigEndian.PutUint16(port, nfRange.RangeIPV4.MinPort)
-		target.MinPort = binary.LittleEndian.Uint16(port)
-
-		binary.BigEndian.PutUint16(port, nfRange.RangeIPV4.MaxPort)
-		target.MaxPort = binary.LittleEndian.Uint16(port)
-		return target, nil
-	}
-
-	// Unknown target.
-	return nil, fmt.Errorf("unknown target %q doesn't exist or isn't supported yet.", target.Name.String())
-}
-
 func filterFromIPTIP(iptip linux.IPTIP) (stack.IPHeaderFilter, error) {
 	if containsUnsupportedFields(iptip) {
 		return stack.IPHeaderFilter{}, fmt.Errorf("unsupported fields in struct iptip: %+v", iptip)
diff --git a/pkg/sentry/socket/netfilter/targets.go b/pkg/sentry/socket/netfilter/targets.go
index b91ba3ab3..8ebdaff18 100644
--- a/pkg/sentry/socket/netfilter/targets.go
+++ b/pkg/sentry/socket/netfilter/targets.go
@@ -15,10 +15,257 @@
 package netfilter
 
 import (
+	"errors"
+	"fmt"
+
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/binary"
 	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
+// errorTargetName is used to mark targets as error targets. Error targets
+// shouldn't be reached - an error has occurred if we fall through to one.
+const errorTargetName = "ERROR"
+
+// redirectTargetName is used to mark targets as redirect targets. Redirect
+// targets should be reached for only NAT and Mangle tables. These targets will
+// change the destination port/destination IP for packets.
+const redirectTargetName = "REDIRECT"
+
+func marshalTarget(target stack.Target) []byte {
+	switch tg := target.(type) {
+	case stack.AcceptTarget:
+		return marshalStandardTarget(stack.RuleAccept)
+	case stack.DropTarget:
+		return marshalStandardTarget(stack.RuleDrop)
+	case stack.ErrorTarget:
+		return marshalErrorTarget(errorTargetName)
+	case stack.UserChainTarget:
+		return marshalErrorTarget(tg.Name)
+	case stack.ReturnTarget:
+		return marshalStandardTarget(stack.RuleReturn)
+	case stack.RedirectTarget:
+		return marshalRedirectTarget(tg)
+	case JumpTarget:
+		return marshalJumpTarget(tg)
+	default:
+		panic(fmt.Errorf("unknown target of type %T", target))
+	}
+}
+
+func marshalStandardTarget(verdict stack.RuleVerdict) []byte {
+	nflog("convert to binary: marshalling standard target")
+
+	// The target's name will be the empty string.
+	target := linux.XTStandardTarget{
+		Target: linux.XTEntryTarget{
+			TargetSize: linux.SizeOfXTStandardTarget,
+		},
+		Verdict: translateFromStandardVerdict(verdict),
+	}
+
+	ret := make([]byte, 0, linux.SizeOfXTStandardTarget)
+	return binary.Marshal(ret, usermem.ByteOrder, target)
+}
+
+func marshalErrorTarget(errorName string) []byte {
+	// This is an error target named error
+	target := linux.XTErrorTarget{
+		Target: linux.XTEntryTarget{
+			TargetSize: linux.SizeOfXTErrorTarget,
+		},
+	}
+	copy(target.Name[:], errorName)
+	copy(target.Target.Name[:], errorTargetName)
+
+	ret := make([]byte, 0, linux.SizeOfXTErrorTarget)
+	return binary.Marshal(ret, usermem.ByteOrder, target)
+}
+
+func marshalRedirectTarget(rt stack.RedirectTarget) []byte {
+	// This is a redirect target named redirect
+	target := linux.XTRedirectTarget{
+		Target: linux.XTEntryTarget{
+			TargetSize: linux.SizeOfXTRedirectTarget,
+		},
+	}
+	copy(target.Target.Name[:], redirectTargetName)
+
+	ret := make([]byte, 0, linux.SizeOfXTRedirectTarget)
+	target.NfRange.RangeSize = 1
+	if rt.RangeProtoSpecified {
+		target.NfRange.RangeIPV4.Flags |= linux.NF_NAT_RANGE_PROTO_SPECIFIED
+	}
+	// Convert port from little endian to big endian.
+	port := make([]byte, 2)
+	binary.LittleEndian.PutUint16(port, rt.MinPort)
+	target.NfRange.RangeIPV4.MinPort = binary.BigEndian.Uint16(port)
+	binary.LittleEndian.PutUint16(port, rt.MaxPort)
+	target.NfRange.RangeIPV4.MaxPort = binary.BigEndian.Uint16(port)
+	return binary.Marshal(ret, usermem.ByteOrder, target)
+}
+
+func marshalJumpTarget(jt JumpTarget) []byte {
+	nflog("convert to binary: marshalling jump target")
+
+	// The target's name will be the empty string.
+	target := linux.XTStandardTarget{
+		Target: linux.XTEntryTarget{
+			TargetSize: linux.SizeOfXTStandardTarget,
+		},
+		// Verdict is overloaded by the ABI. When positive, it holds
+		// the jump offset from the start of the table.
+		Verdict: int32(jt.Offset),
+	}
+
+	ret := make([]byte, 0, linux.SizeOfXTStandardTarget)
+	return binary.Marshal(ret, usermem.ByteOrder, target)
+}
+
+// translateFromStandardVerdict translates verdicts the same way as the iptables
+// tool.
+func translateFromStandardVerdict(verdict stack.RuleVerdict) int32 {
+	switch verdict {
+	case stack.RuleAccept:
+		return -linux.NF_ACCEPT - 1
+	case stack.RuleDrop:
+		return -linux.NF_DROP - 1
+	case stack.RuleReturn:
+		return linux.NF_RETURN
+	default:
+		// TODO(gvisor.dev/issue/170): Support Jump.
+		panic(fmt.Sprintf("unknown standard verdict: %d", verdict))
+	}
+}
+
+// translateToStandardTarget translates from the value in a
+// linux.XTStandardTarget to an stack.Verdict.
+func translateToStandardTarget(val int32) (stack.Target, error) {
+	// TODO(gvisor.dev/issue/170): Support other verdicts.
+	switch val {
+	case -linux.NF_ACCEPT - 1:
+		return stack.AcceptTarget{}, nil
+	case -linux.NF_DROP - 1:
+		return stack.DropTarget{}, nil
+	case -linux.NF_QUEUE - 1:
+		return nil, errors.New("unsupported iptables verdict QUEUE")
+	case linux.NF_RETURN:
+		return stack.ReturnTarget{}, nil
+	default:
+		return nil, fmt.Errorf("unknown iptables verdict %d", val)
+	}
+}
+
+// parseTarget parses a target from optVal. optVal should contain only the
+// target.
+func parseTarget(filter stack.IPHeaderFilter, optVal []byte) (stack.Target, error) {
+	nflog("set entries: parsing target of size %d", len(optVal))
+	if len(optVal) < linux.SizeOfXTEntryTarget {
+		return nil, fmt.Errorf("optVal has insufficient size for entry target %d", len(optVal))
+	}
+	var target linux.XTEntryTarget
+	buf := optVal[:linux.SizeOfXTEntryTarget]
+	binary.Unmarshal(buf, usermem.ByteOrder, &target)
+	switch target.Name.String() {
+	case "":
+		// Standard target.
+		if len(optVal) != linux.SizeOfXTStandardTarget {
+			return nil, fmt.Errorf("optVal has wrong size for standard target %d", len(optVal))
+		}
+		var standardTarget linux.XTStandardTarget
+		buf = optVal[:linux.SizeOfXTStandardTarget]
+		binary.Unmarshal(buf, usermem.ByteOrder, &standardTarget)
+
+		if standardTarget.Verdict < 0 {
+			// A Verdict < 0 indicates a non-jump verdict.
+			return translateToStandardTarget(standardTarget.Verdict)
+		}
+		// A verdict >= 0 indicates a jump.
+		return JumpTarget{Offset: uint32(standardTarget.Verdict)}, nil
+
+	case errorTargetName:
+		// Error target.
+		if len(optVal) != linux.SizeOfXTErrorTarget {
+			return nil, fmt.Errorf("optVal has insufficient size for error target %d", len(optVal))
+		}
+		var errorTarget linux.XTErrorTarget
+		buf = optVal[:linux.SizeOfXTErrorTarget]
+		binary.Unmarshal(buf, usermem.ByteOrder, &errorTarget)
+
+		// Error targets are used in 2 cases:
+		// * An actual error case. These rules have an error
+		//   named errorTargetName. The last entry of the table
+		//   is usually an error case to catch any packets that
+		//   somehow fall through every rule.
+		// * To mark the start of a user defined chain. These
+		//   rules have an error with the name of the chain.
+		switch name := errorTarget.Name.String(); name {
+		case errorTargetName:
+			nflog("set entries: error target")
+			return stack.ErrorTarget{}, nil
+		default:
+			// User defined chain.
+			nflog("set entries: user-defined target %q", name)
+			return stack.UserChainTarget{Name: name}, nil
+		}
+
+	case redirectTargetName:
+		// Redirect target.
+		if len(optVal) < linux.SizeOfXTRedirectTarget {
+			return nil, fmt.Errorf("netfilter.SetEntries: optVal has insufficient size for redirect target %d", len(optVal))
+		}
+
+		if filter.Protocol != header.TCPProtocolNumber && filter.Protocol != header.UDPProtocolNumber {
+			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
+		}
+
+		var redirectTarget linux.XTRedirectTarget
+		buf = optVal[:linux.SizeOfXTRedirectTarget]
+		binary.Unmarshal(buf, usermem.ByteOrder, &redirectTarget)
+
+		// Copy linux.XTRedirectTarget to stack.RedirectTarget.
+		var target stack.RedirectTarget
+		nfRange := redirectTarget.NfRange
+
+		// RangeSize should be 1.
+		if nfRange.RangeSize != 1 {
+			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
+		}
+
+		// TODO(gvisor.dev/issue/170): Check if the flags are valid.
+		// Also check if we need to map ports or IP.
+		// For now, redirect target only supports destination port change.
+		// Port range and IP range are not supported yet.
+		if nfRange.RangeIPV4.Flags&linux.NF_NAT_RANGE_PROTO_SPECIFIED == 0 {
+			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
+		}
+		target.RangeProtoSpecified = true
+
+		target.MinIP = tcpip.Address(nfRange.RangeIPV4.MinIP[:])
+		target.MaxIP = tcpip.Address(nfRange.RangeIPV4.MaxIP[:])
+
+		// TODO(gvisor.dev/issue/170): Port range is not supported yet.
+		if nfRange.RangeIPV4.MinPort != nfRange.RangeIPV4.MaxPort {
+			return nil, fmt.Errorf("netfilter.SetEntries: invalid argument")
+		}
+
+		// Convert port from big endian to little endian.
+		port := make([]byte, 2)
+		binary.BigEndian.PutUint16(port, nfRange.RangeIPV4.MinPort)
+		target.MinPort = binary.LittleEndian.Uint16(port)
+
+		binary.BigEndian.PutUint16(port, nfRange.RangeIPV4.MaxPort)
+		target.MaxPort = binary.LittleEndian.Uint16(port)
+		return target, nil
+	}
+
+	// Unknown target.
+	return nil, fmt.Errorf("unknown target %q doesn't exist or isn't supported yet", target.Name.String())
+}
+
 // JumpTarget implements stack.Target.
 type JumpTarget struct {
 	// Offset is the byte offset of the rule to jump to. It is used for