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// Copyright 2022 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.
package build
import (
"archive/tar"
"compress/gzip"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"time"
"github.com/google/syzkaller/pkg/osutil"
)
const (
kernelConfig = "common/build.config.gki_kasan.x86_64"
moduleConfig = "common-modules/virtual-device/build.config.virtual_device_kasan.x86_64"
bazelTarget = "//common-modules/virtual-device:virtual_device_x86_64_dist"
)
type cuttlefish struct{}
func (c cuttlefish) runBuild(kernelDir, buildConfig string) error {
cmd := osutil.Command("build/build.sh")
cmd.Dir = kernelDir
cmd.Env = append(cmd.Env, "OUT_DIR=out", "DIST_DIR=dist", fmt.Sprintf("BUILD_CONFIG=%s", buildConfig))
_, err := osutil.Run(time.Hour, cmd)
return err
}
func (c cuttlefish) runBazel(kernelDir string) error {
cmd := osutil.Command("tools/bazel", "run", bazelTarget, "--", "--dist_dir=dist")
if err := osutil.Sandbox(cmd, true, false); err != nil {
return fmt.Errorf("failed to sandbox build command: %w", err)
}
cmd.Dir = kernelDir
_, err := osutil.Run(time.Hour, cmd)
return err
}
func (c cuttlefish) createDefconfig(commonDir string, config []byte) error {
configFile := filepath.Join(commonDir, ".config")
if err := osutil.WriteFile(configFile, config); err != nil {
return fmt.Errorf("writing config failed: %w", err)
}
if err := osutil.SandboxChown(configFile); err != nil {
return fmt.Errorf("error changing config owner: %w", err)
}
// Create a 'defconfig' file from full '.config'.
cmd := osutil.Command("make", "savedefconfig")
cmd.Dir = commonDir
if err := osutil.Sandbox(cmd, true, false); err != nil {
return fmt.Errorf("failed to sandbox defconfig creation: %w", err)
}
if _, err := osutil.Run(time.Hour, cmd); err != nil {
return fmt.Errorf("failed to create defconfig: %w", err)
}
// Copy defconfig to expected config directory.
defconfigFile := filepath.Join(commonDir, "arch", "x86", "configs", "gki_defconfig")
if err := os.Rename(filepath.Join(commonDir, "defconfig"), defconfigFile); err != nil {
return fmt.Errorf("writing config failed: %w", err)
}
if err := osutil.SandboxChown(defconfigFile); err != nil {
return fmt.Errorf("error changing defconfig owner: %w", err)
}
if err := os.Remove(configFile); err != nil {
return fmt.Errorf("failure removing temp config: %w", err)
}
return nil
}
func (c cuttlefish) readCompiler(archivePath string) (string, error) {
f, err := os.Open(archivePath)
if err != nil {
return "", err
}
defer f.Close()
gr, err := gzip.NewReader(f)
if err != nil {
return "", err
}
defer gr.Close()
tr := tar.NewReader(gr)
h, err := tr.Next()
for ; err == nil; h, err = tr.Next() {
if filepath.Base(h.Name) == "compile.h" {
bytes, err := io.ReadAll(tr)
if err != nil {
return "", err
}
result := linuxCompilerRegexp.FindSubmatch(bytes)
if result == nil {
return "", fmt.Errorf("include/generated/compile.h does not contain build information")
}
return string(result[1]), nil
}
}
return "", fmt.Errorf("archive %s doesn't contain include/generated/compile.h", archivePath)
}
func (c cuttlefish) build(params Params) (ImageDetails, error) {
var details ImageDetails
if params.CmdlineFile != "" {
return details, fmt.Errorf("cmdline file is not supported for android cuttlefish images")
}
if params.SysctlFile != "" {
return details, fmt.Errorf("sysctl file is not supported for android cuttlefish images")
}
var config string
var err error
// Clean output directory if it exists.
if err := osutil.RemoveAll(filepath.Join(params.KernelDir, "out")); err != nil {
return details, fmt.Errorf("failed to clean before kernel build: %w", err)
}
// Default to build.sh if compiler is not specified.
if params.Compiler == "bazel" {
if params.Config == nil {
return details, errors.New("kernel config was not provided for build")
}
if err := c.createDefconfig(filepath.Join(params.KernelDir, "common"), params.Config); err != nil {
return details, fmt.Errorf("failed to create defconfig file: %w", err)
}
if err := c.runBazel(params.KernelDir); err != nil {
return details, fmt.Errorf("failed to build kernel: %w", err)
}
// Find the .config file; it is placed in a temporary output directory during the build.
cmd := osutil.Command("find", ".", "-regex", ".*virtual_device_x86_64_config.*/\\.config")
cmd.Dir = params.KernelDir
configBytes, err := osutil.Run(time.Minute, cmd)
if err != nil {
return details, fmt.Errorf("failed to find build config: %w", err)
}
config = filepath.Join(params.KernelDir, strings.TrimSpace(string(configBytes)))
} else {
if err := c.runBuild(params.KernelDir, kernelConfig); err != nil {
return details, fmt.Errorf("failed to build kernel: %w", err)
}
if err := c.runBuild(params.KernelDir, moduleConfig); err != nil {
return details, fmt.Errorf("failed to build modules: %w", err)
}
config = filepath.Join(params.KernelDir, "out", "common", ".config")
}
buildDistDir := filepath.Join(params.KernelDir, "dist")
bzImage := filepath.Join(buildDistDir, "bzImage")
vmlinux := filepath.Join(buildDistDir, "vmlinux")
initramfs := filepath.Join(buildDistDir, "initramfs.img")
details.CompilerID, err = c.readCompiler(filepath.Join(buildDistDir, "kernel-headers.tar.gz"))
if err != nil {
return details, err
}
if err := embedFiles(params, func(mountDir string) error {
homeDir := filepath.Join(mountDir, "root")
if err := osutil.CopyFile(bzImage, filepath.Join(homeDir, "bzImage")); err != nil {
return err
}
if err := osutil.CopyFile(vmlinux, filepath.Join(homeDir, "vmlinux")); err != nil {
return err
}
if err := osutil.CopyFile(initramfs, filepath.Join(homeDir, "initramfs.img")); err != nil {
return err
}
return nil
}); err != nil {
return details, err
}
if err := osutil.CopyFile(vmlinux, filepath.Join(params.OutputDir, "obj", "vmlinux")); err != nil {
return details, err
}
if err := osutil.CopyFile(initramfs, filepath.Join(params.OutputDir, "obj", "initrd")); err != nil {
return details, err
}
if err := osutil.CopyFile(config, filepath.Join(params.OutputDir, "kernel.config")); err != nil {
return details, err
}
details.Signature, err = elfBinarySignature(vmlinux, params.Tracer)
if err != nil {
return details, fmt.Errorf("failed to generate signature: %w", err)
}
return details, nil
}
func (c cuttlefish) clean(kernelDir, targetArch string) error {
if err := osutil.RemoveAll(filepath.Join(kernelDir, "out")); err != nil {
return err
}
return osutil.RemoveAll(filepath.Join(kernelDir, "dist"))
}
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