move (re-license) tracing package and introduce 'allowundefined' in k…

…probe struct tag (#37602)

* fix: replace deprecated io/ioutil with os

* fix: rename local vars so they don't collide with built-in functions

* feat: introduce support for allowundefined tag

* fix: remove unnecessary named return variable

* feat: expose the option to set the wakeup_events for the perf channel

* feat: move tracing from x-pack/auditbeat to auditbeat

* legal: re-license tracing from Elastic License to Apache License Version 2.0

* fix: remove deprecated ioutil in events_test.go

* fix: replace naked return(s)

* fix: pre-allocate slices wherever the len is known

* fix: use errors.Is to check for a specific error

* fix: remove unused withTime struct field from PerfChannel

* fix: properly use make(chan struct{})

* fix: use raw string with regexp.MustCompile

* fix: replace missed naked return(s)

* fix: replace pre-allocating len of the slices with cap

* feat: modernise tracing endian.go to use binary.NativeEndian

* feat: refactor copyInt and readInt to use unsafe.Slice

* fix: revert pollAll in perfevent.go to named returns as these can be properly documented

* fix: remove redundant endian.go and utilise directly binary.NativeEndian

* fix: return explicitly the named returns in pollAll

* Revert "fix: remove redundant endian.go and utilise directly binary.NativeEndian"

This reverts commit 19d9c28.

x-pack/auditbeat/tracing/cpu.go → auditbeat/tracing/cpu.go

@@ -1,6 +1,19 @@
-// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
-// or more contributor license agreements. Licensed under the Elastic License;
-// you may not use this file except in compliance with the Elastic License.
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
 
 //go:build linux
 
@@ -9,7 +22,7 @@ package tracing
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strconv"
 	"strings"
 )
@@ -72,7 +85,7 @@ func (s CPUSet) AsList() []int {
 
 // NewCPUSetFromFile creates a new CPUSet from the contents of a file.
 func NewCPUSetFromFile(path string) (cpus CPUSet, err error) {
-	contents, err := ioutil.ReadFile(path)
+	contents, err := os.ReadFile(path)
 	if err != nil {
 		return cpus, err
 	}
@@ -84,9 +97,12 @@ func NewCPUSetFromFile(path string) (cpus CPUSet, err error) {
 // Where:
 // RANGE := <NUMBER> | <NUMBER>-<NUMBER>
 func NewCPUSetFromExpression(contents string) (CPUSet, error) {
-	var ranges [][]int
-	var max, count int
-	for _, expr := range strings.Split(contents, ",") {
+	expressions := strings.Split(contents, ",")
+
+	ranges := make([][]int, 0, len(expressions))
+
+	var maximum, count int
+	for _, expr := range expressions {
 		if len(expr) == 0 {
 			continue
 		}
@@ -99,16 +115,16 @@ func NewCPUSetFromExpression(contents string) (CPUSet, error) {
 			}
 			num := int(num16)
 			r = append(r, num)
-			if num+1 > max {
-				max = num + 1
+			if num+1 > maximum {
+				maximum = num + 1
 			}
 		}
 		ranges = append(ranges, r)
 	}
-	if max == 0 {
+	if maximum == 0 {
 		return CPUSet{}, nil
 	}
-	mask := make([]bool, max)
+	mask := make([]bool, maximum)
 	for _, r := range ranges {
 		from, to := -1, -1
 		switch len(r) {

x-pack/auditbeat/tracing/cpu_test.go → auditbeat/tracing/cpu_test.go

@@ -1,6 +1,19 @@
-// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
-// or more contributor license agreements. Licensed under the Elastic License;
-// you may not use this file except in compliance with the Elastic License.
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
 
 //go:build linux
 

x-pack/auditbeat/tracing/decoder.go → auditbeat/tracing/decoder.go

@@ -1,6 +1,19 @@
-// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
-// or more contributor license agreements. Licensed under the Elastic License;
-// you may not use this file except in compliance with the Elastic License.
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
 
 //go:build linux
 
@@ -183,9 +196,13 @@ func NewStructDecoder(desc ProbeFormat, allocFn AllocateFn) (Decoder, error) {
 		}
 
 		var name string
+		var allowUndefined bool
 		var greedy bool
 		for idx, param := range strings.Split(values, ",") {
 			switch param {
+			case "allowundefined":
+				// it is okay not to find it in the desc.Fields
+				allowUndefined = true
 			case "greedy":
 				greedy = true
 			default:
@@ -214,6 +231,9 @@ func NewStructDecoder(desc ProbeFormat, allocFn AllocateFn) (Decoder, error) {
 
 		inField, found := desc.Fields[name]
 		if !found {
+			if allowUndefined {
+				continue
+			}
 			return nil, fmt.Errorf("field '%s' not found in kprobe format description", name)
 		}
 
@@ -326,14 +346,14 @@ func (d *structDecoder) Decode(raw []byte, meta Metadata) (s interface{}, err er
 
 		case FieldTypeString:
 			offset := uintptr(MachineEndian.Uint16(raw[dec.src:]))
-			len := uintptr(MachineEndian.Uint16(raw[dec.src+2:]))
-			if offset+len > n {
+			length := uintptr(MachineEndian.Uint16(raw[dec.src+2:]))
+			if offset+length > n {
 				return nil, fmt.Errorf("perf event string data for field %s overflows message of size %d", dec.name, n)
 			}
-			if len > 0 && raw[offset+len-1] == 0 {
-				len--
+			if length > 0 && raw[offset+length-1] == 0 {
+				length--
 			}
-			*(*string)(unsafe.Add(destPtr, dec.dst)) = string(raw[offset : offset+len])
+			*(*string)(unsafe.Add(destPtr, dec.dst)) = string(raw[offset : offset+length])
 
 		case FieldTypeMeta:
 			*(*Metadata)(unsafe.Add(destPtr, dec.dst)) = meta
@@ -357,7 +377,8 @@ type dumpDecoder struct {
 // - integer of 64bit (u64 / s64).
 // - dump consecutive memory.
 func NewDumpDecoder(format ProbeFormat) (Decoder, error) {
-	var fields []Field
+	fields := make([]Field, 0, len(format.Fields))
+
 	for name, field := range format.Fields {
 		if strings.Index(name, "arg") != 0 {
 			continue

auditbeat/tracing/doc.go

@@ -0,0 +1,22 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+// Package tracing provides a set of tools built on top of
+// golang.org/x/sys/unix/linux/perf that simplify working with KProbes and
+// UProbes, using tracing perf channels to receive events from the kernel and
+// decoding of this raw events into more useful types.
+package tracing

auditbeat/tracing/endian.go

@@ -0,0 +1,28 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//go:build linux
+
+package tracing
+
+import (
+	"encoding/binary"
+)
+
+// MachineEndian is either binary.BigEndian or binary.LittleEndian, depending
+// on the current architecture.
+var MachineEndian = binary.NativeEndian

x-pack/auditbeat/tracing/events_test.go → auditbeat/tracing/events_test.go

@@ -1,6 +1,19 @@
-// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
-// or more contributor license agreements. Licensed under the Elastic License;
-// you may not use this file except in compliance with the Elastic License.
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
 
 //go:build linux
 
@@ -9,7 +22,6 @@ package tracing
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -301,7 +313,7 @@ func TestKProbeReal(t *testing.T) {
 
 func TestKProbeEventsList(t *testing.T) {
 	// Make dir to monitor.
-	tmpDir, err := ioutil.TempDir("", "events_test")
+	tmpDir, err := os.MkdirTemp("", "events_test")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -358,7 +370,7 @@ w:future feature
 
 func TestKProbeEventsAddRemoveKProbe(t *testing.T) {
 	// Make dir to monitor.
-	tmpDir, err := ioutil.TempDir("", "events_test")
+	tmpDir, err := os.MkdirTemp("", "events_test")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -397,7 +409,7 @@ w:future feature
 	off, err := file.Seek(int64(0), io.SeekStart)
 	assert.NoError(t, err)
 	assert.Equal(t, int64(0), off)
-	contents, err := ioutil.ReadAll(file)
+	contents, err := io.ReadAll(file)
 	assert.NoError(t, err)
 	expected := append([]byte(baseContents), []byte(
 		`p:kprobe/myprobe sys_open path=+0(%di):string mode=%si

auditbeat/tracing/int_aligned.go

@@ -0,0 +1,71 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//go:build linux && !386 && !amd64 && !amd64p32
+
+// Alignment-safe integer reading and writing functions.
+
+package tracing
+
+import (
+	"errors"
+	"unsafe"
+)
+
+var errBadSize = errors.New("bad size for integer")
+
+func copyInt(dst unsafe.Pointer, src unsafe.Pointer, len uint8) error {
+	copy(unsafe.Slice((*byte)(dst), len), unsafe.Slice((*byte)(src), len))
+	return nil
+}
+
+func readInt(ptr unsafe.Pointer, len uint8, signed bool) (any, error) {
+	var value any
+	asSlice := unsafe.Slice((*byte)(ptr), len)
+	switch len {
+	case 1:
+		if signed {
+			value = int8(asSlice[0])
+		} else {
+			value = asSlice[0]
+		}
+	case 2:
+		if signed {
+			value = int16(MachineEndian.Uint16(asSlice))
+		} else {
+			value = MachineEndian.Uint16(asSlice)
+		}
+
+	case 4:
+		if signed {
+			value = int32(MachineEndian.Uint32(asSlice))
+		} else {
+			value = MachineEndian.Uint32(asSlice)
+		}
+
+	case 8:
+		if signed {
+			value = int64(MachineEndian.Uint64(asSlice))
+		} else {
+			value = MachineEndian.Uint64(asSlice)
+		}
+
+	default:
+		return nil, errBadSize
+	}
+	return value, nil
+}