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Add BPF TcAction support to U32 filter 

Current U32 filter only supports redirect action, but the U32 can
support a lot more. Refactor a bit the action generating/parsing logic
to be more generic and add BPF action support.

When creating a U32 filter, one can supply an array of Actions, which
will be executed by the U32 filter in order:
* The new MirredAction implements the same functionality as RedirIndex
  field in the U32 filter, with that static field kept in the struct for
  backwards compatibility.
* A new BpfAction type is added which allows a program with an open bpf
  file descriptor (implementation is out of scope of this patch) to be
  added as well.

Add a test for the above use case which includes one of each type of
action.
This commit is contained in:
Brenden Blanco 2016-02-28 23:12:34 -08:00
parent 1f71a4c2a6
commit 6f0327edfd
4 changed files with 310 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
bpf_linux.go Normal file
View File

@ -0,0 +1,53 @@
package netlink
/*
#include <asm/types.h>
#include <asm/unistd.h>
#include <stdio.h>
#include <unistd.h>
static int load_simple_bpf(int prog_type) {
// { return 1; }
__u64 __attribute__((aligned(8))) insns[] = {
0x00000001000000b7ull,
0x0000000000000095ull,
};
__u8 __attribute__((aligned(8))) license[] = "ASL2";
// Copied from a header file since libc is notoriously slow to update.
// The call will succeed or fail and that will be our indication on
// whether or not it is supported.
struct {
__u32 prog_type;
__u32 insn_cnt;
__u64 insns;
__u64 license;
__u32 log_level;
__u32 log_size;
__u64 log_buf;
__u32 kern_version;
} __attribute__((aligned(8))) attr = {
.prog_type = prog_type,
.insn_cnt = 2,
.insns = (__u64)&insns,
.license = (__u64)&license,
};
return syscall(__NR_bpf, 5, &attr, sizeof(attr));
}
*/
import "C"
type BpfProgType C.int
const (
BPF_PROG_TYPE_UNSPEC BpfProgType = iota
BPF_PROG_TYPE_SOCKET_FILTER
BPF_PROG_TYPE_KPROBE
BPF_PROG_TYPE_SCHED_CLS
BPF_PROG_TYPE_SCHED_ACT
)
// loadSimpleBpf loads a trivial bpf program for testing purposes
func loadSimpleBpf(progType BpfProgType) (int, error) {
fd, err := C.load_simple_bpf(C.int(progType))
return int(fd), err
}

36
filter.go
View File

@ -26,11 +26,45 @@ func (q FilterAttrs) String() string {
return fmt.Sprintf("{LinkIndex: %d, Handle: %s, Parent: %s, Priority: %d, Protocol: %d}", q.LinkIndex, HandleStr(q.Handle), HandleStr(q.Parent), q.Priority, q.Protocol)
}
// Action represents an action in any supported filter.
type Action interface {
Type() string
}
type BpfAction struct {
nl.TcActBpf
Fd int
Name string
}
func (action *BpfAction) Type() string {
return "bpf"
}
type MirredAction struct {
nl.TcMirred
}
func (action *MirredAction) Type() string {
return "mirred"
}
func NewMirredAction(redirIndex int) *MirredAction {
return &MirredAction{
TcMirred: nl.TcMirred{
TcGen: nl.TcGen{Action: nl.TC_ACT_STOLEN},
Eaction: nl.TCA_EGRESS_REDIR,
Ifindex: uint32(redirIndex),
},
}
}
// U32 filters on many packet related properties
type U32 struct {
FilterAttrs
// Currently only supports redirecting to another interface
ClassId uint32
RedirIndex int
Actions []Action
}
func (filter *U32) Attrs() *FilterAttrs {

142
filter_linux.go
View File

@ -52,17 +52,17 @@ func FilterAdd(filter Filter) error {
}
sel.Keys = append(sel.Keys, nl.TcU32Key{})
nl.NewRtAttrChild(options, nl.TCA_U32_SEL, sel.Serialize())
actions := nl.NewRtAttrChild(options, nl.TCA_U32_ACT, nil)
table := nl.NewRtAttrChild(actions, nl.TCA_ACT_TAB, nil)
nl.NewRtAttrChild(table, nl.TCA_KIND, nl.ZeroTerminated("mirred"))
// redirect to other interface
mir := nl.TcMirred{
Action: nl.TC_ACT_STOLEN,
Eaction: nl.TCA_EGRESS_REDIR,
Ifindex: uint32(u32.RedirIndex),
if u32.ClassId != 0 {
nl.NewRtAttrChild(options, nl.TCA_U32_CLASSID, nl.Uint32Attr(u32.ClassId))
}
actionsAttr := nl.NewRtAttrChild(options, nl.TCA_U32_ACT, nil)
// backwards compatibility
if u32.RedirIndex != 0 {
u32.Actions = append([]Action{NewMirredAction(u32.RedirIndex)}, u32.Actions...)
}
if err := encodeActions(actionsAttr, u32.Actions); err != nil {
return err
}
aopts := nl.NewRtAttrChild(table, nl.TCA_OPTIONS, nil)
nl.NewRtAttrChild(aopts, nl.TCA_MIRRED_PARMS, mir.Serialize())
} else if fw, ok := filter.(*Fw); ok {
if fw.Mask != 0 {
b := make([]byte, 4)
@ -151,21 +151,17 @@ func FilterList(link Link, parent uint32) ([]Filter, error) {
filter = &GenericFilter{FilterType: filterType}
}
case nl.TCA_OPTIONS:
data, err := nl.ParseRouteAttr(attr.Value)
if err != nil {
return nil, err
}
switch filterType {
case "u32":
data, err := nl.ParseRouteAttr(attr.Value)
if err != nil {
return nil, err
}
detailed, err = parseU32Data(filter, data)
if err != nil {
return nil, err
}
case "fw":
data, err := nl.ParseRouteAttr(attr.Value)
if err != nil {
return nil, err
}
detailed, err = parseFwData(filter, data)
if err != nil {
return nil, err
@ -183,6 +179,85 @@ func FilterList(link Link, parent uint32) ([]Filter, error) {
return res, nil
}
func encodeActions(attr *nl.RtAttr, actions []Action) error {
tabIndex := int(nl.TCA_ACT_TAB)
for _, action := range actions {
switch action := action.(type) {
default:
return fmt.Errorf("unknown action type %s", action.Type())
case *MirredAction:
table := nl.NewRtAttrChild(attr, tabIndex, nil)
tabIndex++
nl.NewRtAttrChild(table, nl.TCA_ACT_KIND, nl.ZeroTerminated("mirred"))
aopts := nl.NewRtAttrChild(table, nl.TCA_ACT_OPTIONS, nil)
nl.NewRtAttrChild(aopts, nl.TCA_MIRRED_PARMS, action.Serialize())
case *BpfAction:
table := nl.NewRtAttrChild(attr, tabIndex, nil)
tabIndex++
nl.NewRtAttrChild(table, nl.TCA_ACT_KIND, nl.ZeroTerminated("bpf"))
aopts := nl.NewRtAttrChild(table, nl.TCA_ACT_OPTIONS, nil)
nl.NewRtAttrChild(aopts, nl.TCA_ACT_BPF_PARMS, action.Serialize())
nl.NewRtAttrChild(aopts, nl.TCA_ACT_BPF_FD, nl.Uint32Attr(uint32(action.Fd)))
nl.NewRtAttrChild(aopts, nl.TCA_ACT_BPF_NAME, nl.ZeroTerminated(action.Name))
}
}
return nil
}
func parseActions(tables []syscall.NetlinkRouteAttr) ([]Action, error) {
var actions []Action
for _, table := range tables {
var action Action
var actionType string
aattrs, err := nl.ParseRouteAttr(table.Value)
if err != nil {
return nil, err
}
nextattr:
for _, aattr := range aattrs {
switch aattr.Attr.Type {
case nl.TCA_KIND:
actionType = string(aattr.Value[:len(aattr.Value)-1])
// only parse if the action is mirred or bpf
switch actionType {
case "mirred":
action = &MirredAction{}
case "bpf":
action = &BpfAction{}
default:
break nextattr
}
case nl.TCA_OPTIONS:
adata, err := nl.ParseRouteAttr(aattr.Value)
if err != nil {
return nil, err
}
for _, adatum := range adata {
switch actionType {
case "mirred":
switch adatum.Attr.Type {
case nl.TCA_MIRRED_PARMS:
action.(*MirredAction).TcMirred = *nl.DeserializeTcMirred(adatum.Value)
}
case "bpf":
switch adatum.Attr.Type {
case nl.TCA_ACT_BPF_PARMS:
action.(*BpfAction).TcActBpf = *nl.DeserializeTcActBpf(adatum.Value)
case nl.TCA_ACT_BPF_FD:
action.(*BpfAction).Fd = int(native.Uint32(adatum.Value[0:4]))
case nl.TCA_ACT_BPF_NAME:
action.(*BpfAction).Name = string(adatum.Value[:len(adatum.Value)-1])
}
}
}
}
}
actions = append(actions, action)
}
return actions, nil
}
func parseU32Data(filter Filter, data []syscall.NetlinkRouteAttr) (bool, error) {
native = nl.NativeEndian()
u32 := filter.(*U32)
@ -197,34 +272,17 @@ func parseU32Data(filter Filter, data []syscall.NetlinkRouteAttr) (bool, error)
return detailed, nil
}
case nl.TCA_U32_ACT:
table, err := nl.ParseRouteAttr(datum.Value)
tables, err := nl.ParseRouteAttr(datum.Value)
if err != nil {
return detailed, err
}
if len(table) != 1 || table[0].Attr.Type != nl.TCA_ACT_TAB {
return detailed, fmt.Errorf("Action table not formed properly")
u32.Actions, err = parseActions(tables)
if err != nil {
return detailed, err
}
aattrs, err := nl.ParseRouteAttr(table[0].Value)
for _, aattr := range aattrs {
switch aattr.Attr.Type {
case nl.TCA_KIND:
actionType := string(aattr.Value[:len(aattr.Value)-1])
// only parse if the action is mirred
if actionType != "mirred" {
return detailed, nil
}
case nl.TCA_OPTIONS:
adata, err := nl.ParseRouteAttr(aattr.Value)
if err != nil {
return detailed, err
}
for _, adatum := range adata {
switch adatum.Attr.Type {
case nl.TCA_MIRRED_PARMS:
mir := nl.DeserializeTcMirred(adatum.Value)
u32.RedirIndex = int(mir.Ifindex)
}
}
for _, action := range u32.Actions {
if action, ok := action.(*MirredAction); ok {
u32.RedirIndex = int(action.Ifindex)
}
}
}

122
filter_test.go
View File

@ -246,3 +246,125 @@ func TestFilterFwAddDel(t *testing.T) {
t.Fatal("Failed to remove qdisc")
}
}
func TestFilterU32BpfAddDel(t *testing.T) {
tearDown := setUpNetlinkTest(t)
defer tearDown()
if err := LinkAdd(&Ifb{LinkAttrs{Name: "foo"}}); err != nil {
t.Fatal(err)
}
if err := LinkAdd(&Ifb{LinkAttrs{Name: "bar"}}); err != nil {
t.Fatal(err)
}
link, err := LinkByName("foo")
if err != nil {
t.Fatal(err)
}
if err := LinkSetUp(link); err != nil {
t.Fatal(err)
}
redir, err := LinkByName("bar")
if err != nil {
t.Fatal(err)
}
if err := LinkSetUp(redir); err != nil {
t.Fatal(err)
}
qdisc := &Ingress{
QdiscAttrs: QdiscAttrs{
LinkIndex: link.Attrs().Index,
Handle: MakeHandle(0xffff, 0),
Parent: HANDLE_INGRESS,
},
}
if err := QdiscAdd(qdisc); err != nil {
t.Fatal(err)
}
qdiscs, err := QdiscList(link)
if err != nil {
t.Fatal(err)
}
if len(qdiscs) != 1 {
t.Fatal("Failed to add qdisc")
}
_, ok := qdiscs[0].(*Ingress)
if !ok {
t.Fatal("Qdisc is the wrong type")
}
fd, err := loadSimpleBpf(BPF_PROG_TYPE_SCHED_ACT)
if err != nil {
t.Fatal(err)
}
filter := &U32{
FilterAttrs: FilterAttrs{
LinkIndex: link.Attrs().Index,
Parent: MakeHandle(0xffff, 0),
Priority: 1,
Protocol: syscall.ETH_P_ALL,
},
ClassId: MakeHandle(1, 1),
Actions: []Action{
&BpfAction{Fd: fd, Name: "simple"},
&MirredAction{
TcMirred: nl.TcMirred{
TcGen: nl.TcGen{Action: nl.TC_ACT_STOLEN},
Eaction: nl.TCA_EGRESS_REDIR,
Ifindex: uint32(redir.Attrs().Index),
},
},
},
}
if err := FilterAdd(filter); err != nil {
t.Fatal(err)
}
filters, err := FilterList(link, MakeHandle(0xffff, 0))
if err != nil {
t.Fatal(err)
}
if len(filters) != 1 {
t.Fatal("Failed to add filter")
}
u32, ok := filters[0].(*U32)
if !ok {
t.Fatal("Filter is the wrong type")
}
if len(u32.Actions) != 2 {
t.Fatalf("Too few Actions in filter")
}
bpfAction, ok := u32.Actions[0].(*BpfAction)
if !ok {
t.Fatal("Action[0] is the wrong type")
}
if bpfAction.Fd != fd {
t.Fatal("Action Fd does not match")
}
if _, ok := u32.Actions[1].(*MirredAction); !ok {
t.Fatal("Action[1] is the wrong type")
}
if err := FilterDel(filter); err != nil {
t.Fatal(err)
}
filters, err = FilterList(link, MakeHandle(0xffff, 0))
if err != nil {
t.Fatal(err)
}
if len(filters) != 0 {
t.Fatal("Failed to remove filter")
}
if err := QdiscDel(qdisc); err != nil {
t.Fatal(err)
}
qdiscs, err = QdiscList(link)
if err != nil {
t.Fatal(err)
}
if len(qdiscs) != 0 {
t.Fatal("Failed to remove qdisc")
}
}