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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' > linux_generated.go"
//go:generate bash -c "echo -en 'package build\n\n' >> linux_generated.go"
//go:generate bash -c "echo -en 'const createImageScript = `#!/bin/bash\n' >> linux_generated.go"
//go:generate bash -c "cat ../../tools/create-gce-image.sh | grep -v '#' >> linux_generated.go"
//go:generate bash -c "echo -en '`\n\n' >> linux_generated.go"
package build
import (
"crypto/sha1"
"debug/elf"
"encoding/hex"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"runtime"
"time"
"github.com/google/syzkaller/pkg/osutil"
)
type linux struct{}
func (linux linux) build(params *Params) error {
if err := linux.buildKernel(params); err != nil {
return err
}
if err := linux.createImage(params); err != nil {
return err
}
return nil
}
func (linux) buildKernel(params *Params) error {
configFile := filepath.Join(params.KernelDir, ".config")
if err := osutil.WriteFile(configFile, params.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.
// Note: passing in compiler is important since 4.17 (at the very least it's noted in the config).
if err := runMake(params.KernelDir, "oldconfig", "CC="+params.Compiler); err != nil {
return err
}
// Write updated kernel config early, so that it's captured on build failures.
outputConfig := filepath.Join(params.OutputDir, "kernel.config")
if err := osutil.CopyFile(configFile, outputConfig); err != nil {
return err
}
// We build only zImage/bzImage as we currently don't use modules.
var target string
switch params.TargetArch {
case "386", "amd64":
target = "bzImage"
case "ppc64le":
target = "zImage"
}
if err := runMake(params.KernelDir, target, "CC="+params.Compiler); err != nil {
return err
}
vmlinux := filepath.Join(params.KernelDir, "vmlinux")
outputVmlinux := filepath.Join(params.OutputDir, "obj", "vmlinux")
if err := osutil.Rename(vmlinux, outputVmlinux); err != nil {
return fmt.Errorf("failed to rename vmlinux: %v", err)
}
return nil
}
func (linux) createImage(params *Params) error {
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)
}
var kernelImage string
switch params.TargetArch {
case "386", "amd64":
kernelImage = "arch/x86/boot/bzImage"
case "ppc64le":
kernelImage = "arch/powerpc/boot/zImage.pseries"
}
kernelImagePath := filepath.Join(params.KernelDir, filepath.FromSlash(kernelImage))
cmd := osutil.Command(scriptFile, params.UserspaceDir, kernelImagePath, params.TargetArch)
cmd.Dir = tempDir
cmd.Env = append([]string{}, os.Environ()...)
cmd.Env = append(cmd.Env,
"SYZ_VM_TYPE="+params.VMType,
"SYZ_CMDLINE_FILE="+osutil.Abs(params.CmdlineFile),
"SYZ_SYSCTL_FILE="+osutil.Abs(params.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.
imageFile := filepath.Join(params.OutputDir, "image")
if err := osutil.CopyFile(filepath.Join(tempDir, "disk.raw"), imageFile); err != nil {
return err
}
keyFile := filepath.Join(params.OutputDir, "key")
if err := osutil.CopyFile(filepath.Join(tempDir, "key"), keyFile); err != nil {
return err
}
if err := os.Chmod(keyFile, 0600); err != nil {
return err
}
return nil
}
func (linux) clean(kernelDir, targetArch string) error {
return runMake(kernelDir, "distclean")
}
func runMake(kernelDir string, args ...string) error {
args = append(args, fmt.Sprintf("-j%v", runtime.NumCPU()))
cmd := osutil.Command("make", args...)
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Dir = kernelDir
cmd.Env = append([]string{}, os.Environ()...)
// This makes the build [more] deterministic:
// 2 builds from the same sources should result in the same vmlinux binary.
// We plan to use it for detecting no-op changes during bisection.
cmd.Env = append(cmd.Env,
"KBUILD_BUILD_VERSION=0",
"KBUILD_BUILD_TIMESTAMP=now",
"KBUILD_BUILD_USER=syzkaller",
"KBUILD_BUILD_HOST=syzkaller",
)
_, err := osutil.Run(time.Hour, cmd)
return err
}
// elfBinarySignature calculates signature of an elf binary aiming at runtime behavior
// (text/data, debug info is ignored).
func elfBinarySignature(bin string) (string, error) {
f, err := os.Open(bin)
if err != nil {
return "", fmt.Errorf("failed to open binary for signature: %v", err)
}
ef, err := elf.NewFile(f)
if err != nil {
return "", fmt.Errorf("failed to open elf binary: %v", err)
}
hasher := sha1.New()
for _, sec := range ef.Sections {
// Hash allocated sections (e.g. no debug info as it's not allocated)
// with file data (e.g. no bss). We also ignore .notes section as it
// contains some small changing binary blob that seems irrelevant.
// It's unclear if it's better to check NOTE type,
// or ".notes" name or !PROGBITS type.
if sec.Flags&elf.SHF_ALLOC == 0 || sec.Type == elf.SHT_NOBITS || sec.Type == elf.SHT_NOTE {
continue
}
io.Copy(hasher, sec.Open())
}
return hex.EncodeToString(hasher.Sum(nil)), nil
}
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