pkg/kernel: add new package

Move functionality to build kernel/image
from syz-gce to a separate package.

1 files changed, 74 insertions, 0 deletions

diff --git a/pkg/kernel/kernel.go b/pkg/kernel/kernel.go
new file mode 100644
index 000000000..80a8e29c6
--- /dev/null
+++ b/pkg/kernel/kernel.go
@@ -0,0 +1,74 @@
+// 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 (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"time"
+
+	"github.com/google/syzkaller/pkg/osutil"
+)
+
+func Build(dir, compiler, config string) error {
+	const timeout = 10 * time.Minute // default timeout for command invocations
+	os.Remove(filepath.Join(dir, ".config"))
+	configFile := filepath.Join(dir, "syz.config")
+	if err := ioutil.WriteFile(configFile, []byte(config), 0600); err != nil {
+		return fmt.Errorf("failed to write config file: %v", err)
+	}
+	if _, err := osutil.RunCmd(timeout, dir, "make", "defconfig"); err != nil {
+		return err
+	}
+	if _, err := osutil.RunCmd(timeout, dir, "make", "kvmconfig"); err != nil {
+		return err
+	}
+	if _, err := osutil.RunCmd(timeout, dir, "scripts/kconfig/merge_config.sh", "-n", ".config", configFile); err != nil {
+		return err
+	}
+	if _, err := osutil.RunCmd(timeout, dir, "make", "olddefconfig"); err != nil {
+		return err
+	}
+	// Build of a large kernel can take a while on a 1 CPU VM.
+	if _, err := osutil.RunCmd(3*time.Hour, dir, "make", "-j", strconv.Itoa(runtime.NumCPU()*2), "CC="+compiler); err != nil {
+		return err
+	}
+	return nil
+}
+
+// CreateImage creates a disk image that is suitable for syzkaller.
+// Kernel is taken from kernelDir, userspace system is taken from userspaceDir.
+// The resulting image is marked with tag and copied to the specified image file.
+func CreateImage(kernelDir, userspaceDir, tag, image string) error {
+	tempDir, err := ioutil.TempDir("", "syz-build")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(tempDir)
+	scriptFile := filepath.Join(tempDir, "create.sh")
+	if err := ioutil.WriteFile(scriptFile, []byte(createImageScript), 0700); err != nil {
+		return fmt.Errorf("failed to write script file: %v", err)
+	}
+	vmlinux := filepath.Join(kernelDir, "vmlinux")
+	bzImage := filepath.Join(kernelDir, "arch/x86/boot/bzImage")
+	if _, err := osutil.RunCmd(time.Hour, tempDir, scriptFile, userspaceDir, bzImage, vmlinux, tag); err != nil {
+		return fmt.Errorf("image build failed: %v", err)
+	}
+	if err := os.Rename(filepath.Join(tempDir, "image.tar.gz"), image); err != nil {
+		return err
+	}
+	return nil
+}