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// Copyright 2017 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
//go:generate bash -c "echo -en '// AUTOGENERATED FILE\n\n' > generated.go"
//go:generate bash -c "echo -en 'package kernel\n\n' >> generated.go"
//go:generate bash -c "echo -en 'const createImageScript = `#!/bin/bash\n' >> generated.go"
//go:generate bash -c "cat ../../tools/create-gce-image.sh | grep -v '#' >> generated.go"
//go:generate bash -c "echo -en '`\n\n' >> generated.go"
// Package kernel contains helper functions for working with Linux kernel
// (building kernel/image).
package kernel
import (
"bytes"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"time"
"github.com/google/syzkaller/pkg/osutil"
)
func Build(dir, compiler string, config []byte) error {
configFile := filepath.Join(dir, ".config")
if err := osutil.WriteFile(configFile, config); err != nil {
return fmt.Errorf("failed to write config file: %v", err)
}
if err := osutil.SandboxChown(configFile); err != nil {
return err
}
// One would expect olddefconfig here, but olddefconfig is not present in v3.6 and below.
// oldconfig is the same as olddefconfig if stdin is not set.
cmd := osutil.Command("make", "oldconfig")
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Dir = dir
if _, err := osutil.Run(10*time.Minute, cmd); err != nil {
return err
}
// We build only bzImage as we currently don't use modules.
cpu := strconv.Itoa(runtime.NumCPU())
cmd = osutil.Command("make", "bzImage", "-j", cpu, "CC="+compiler)
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Dir = dir
// Build of a large kernel can take a while on a 1 CPU VM.
if _, err := osutil.Run(3*time.Hour, cmd); err != nil {
return extractRootCause(err)
}
return nil
}
func Clean(dir string) error {
cpu := strconv.Itoa(runtime.NumCPU())
cmd := osutil.Command("make", "distclean", "-j", cpu)
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Dir = dir
_, err := osutil.Run(10*time.Minute, cmd)
return err
}
// CreateImage creates a disk image that is suitable for syzkaller.
// Kernel is taken from kernelDir, userspace system is taken from userspaceDir.
// If cmdlineFile is not empty, contents of the file are appended to the kernel command line.
// If sysctlFile is not empty, contents of the file are appended to the image /etc/sysctl.conf.
// Produces image and root ssh key in the specified files.
func CreateImage(targetOS, targetArch, vmType, kernelDir, userspaceDir, cmdlineFile, sysctlFile,
image, sshkey string) error {
if targetOS != "linux" || targetArch != "amd64" {
return fmt.Errorf("only linux/amd64 is supported")
}
if vmType != "qemu" && vmType != "gce" {
return fmt.Errorf("images can be built only for qemu/gce machines")
}
tempDir, err := ioutil.TempDir("", "syz-build")
if err != nil {
return err
}
defer os.RemoveAll(tempDir)
scriptFile := filepath.Join(tempDir, "create.sh")
if err := osutil.WriteExecFile(scriptFile, []byte(createImageScript)); err != nil {
return fmt.Errorf("failed to write script file: %v", err)
}
bzImage := filepath.Join(kernelDir, filepath.FromSlash("arch/x86/boot/bzImage"))
cmd := osutil.Command(scriptFile, userspaceDir, bzImage)
cmd.Dir = tempDir
cmd.Env = append([]string{}, os.Environ()...)
cmd.Env = append(cmd.Env,
"SYZ_VM_TYPE="+vmType,
"SYZ_CMDLINE_FILE="+osutil.Abs(cmdlineFile),
"SYZ_SYSCTL_FILE="+osutil.Abs(sysctlFile),
)
if _, err = osutil.Run(time.Hour, cmd); err != nil {
return fmt.Errorf("image build failed: %v", err)
}
// Note: we use CopyFile instead of Rename because src and dst can be on different filesystems.
if err := osutil.CopyFile(filepath.Join(tempDir, "disk.raw"), image); err != nil {
return err
}
if err := osutil.CopyFile(filepath.Join(tempDir, "key"), sshkey); err != nil {
return err
}
if err := os.Chmod(sshkey, 0600); err != nil {
return err
}
return nil
}
func CompilerIdentity(compiler string) (string, error) {
output, err := osutil.RunCmd(time.Minute, "", compiler, "--version")
if err != nil {
return "", err
}
if len(output) == 0 {
return "", fmt.Errorf("no output from compiler --version")
}
return strings.Split(string(output), "\n")[0], nil
}
func extractRootCause(err error) error {
verr, ok := err.(*osutil.VerboseError)
if !ok {
return err
}
var cause []byte
for _, line := range bytes.Split(verr.Output, []byte{'\n'}) {
for _, pattern := range buildFailureCauses {
if pattern.weak && cause != nil {
continue
}
if bytes.Contains(line, pattern.pattern) {
cause = line
break
}
}
}
if cause != nil {
verr.Title = string(cause)
}
return verr
}
type buildFailureCause struct {
pattern []byte
weak bool
}
var buildFailureCauses = [...]buildFailureCause{
{pattern: []byte(": error: ")},
{pattern: []byte(": fatal error: ")},
{pattern: []byte(": undefined reference to")},
{weak: true, pattern: []byte(": final link failed: ")},
{weak: true, pattern: []byte("collect2: error: ")},
}
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