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archive.go
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archive.go
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package mkcw
import (
"archive/tar"
"bytes"
"compress/gzip"
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"io"
"io/fs"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"time"
"github.com/containers/buildah/internal/tmpdir"
"github.com/containers/buildah/pkg/overlay"
"github.com/containers/luksy"
"github.com/containers/storage/pkg/idtools"
"github.com/containers/storage/pkg/mount"
"github.com/containers/storage/pkg/system"
"github.com/docker/docker/pkg/ioutils"
"github.com/docker/go-units"
digest "github.com/opencontainers/go-digest"
v1 "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/sirupsen/logrus"
)
const minimumImageSize = 10 * 1024 * 1024
// ArchiveOptions includes optional settings for generating an archive.
type ArchiveOptions struct {
// If supplied, we'll register the workload with this server.
// Practically necessary if DiskEncryptionPassphrase is not set, in
// which case we'll generate one and throw it away after.
AttestationURL string
// Used to measure the environment. If left unset (0, ""), defaults will be applied.
CPUs int
Memory int
// Can be manually set. If left unset ("", false, nil), reasonable values will be used.
TempDir string
TeeType TeeType
IgnoreAttestationErrors bool
ImageSize int64
WorkloadID string
Slop string
DiskEncryptionPassphrase string
FirmwareLibrary string
Logger *logrus.Logger
GraphOptions []string // passed in from a storage Store, probably
ExtraImageContent map[string]string
}
type chainRetrievalError struct {
stderr string
err error
}
func (c chainRetrievalError) Error() string {
if trimmed := strings.TrimSpace(c.stderr); trimmed != "" {
return fmt.Sprintf("retrieving SEV certificate chain: sevctl: %v: %v", strings.TrimSpace(c.stderr), c.err)
}
return fmt.Sprintf("retrieving SEV certificate chain: sevctl: %v", c.err)
}
// Archive generates a WorkloadConfig for a specified directory and produces a
// tar archive of a container image's rootfs with the expected contents.
func Archive(rootfsPath string, ociConfig *v1.Image, options ArchiveOptions) (io.ReadCloser, WorkloadConfig, error) {
const (
teeDefaultCPUs = 2
teeDefaultMemory = 512
teeDefaultFilesystem = "ext4"
teeDefaultTeeType = SNP
)
if rootfsPath == "" {
return nil, WorkloadConfig{}, fmt.Errorf("required path not specified")
}
logger := options.Logger
if logger == nil {
logger = logrus.StandardLogger()
}
teeType := options.TeeType
if teeType == "" {
teeType = teeDefaultTeeType
}
cpus := options.CPUs
if cpus == 0 {
cpus = teeDefaultCPUs
}
memory := options.Memory
if memory == 0 {
memory = teeDefaultMemory
}
filesystem := teeDefaultFilesystem
workloadID := options.WorkloadID
if workloadID == "" {
digestInput := rootfsPath + filesystem + time.Now().String()
workloadID = digest.Canonical.FromString(digestInput).Encoded()
}
workloadConfig := WorkloadConfig{
Type: teeType,
WorkloadID: workloadID,
CPUs: cpus,
Memory: memory,
AttestationURL: options.AttestationURL,
}
if options.TempDir == "" {
options.TempDir = tmpdir.GetTempDir()
}
// Do things which are specific to the type of TEE we're building for.
var chainBytes []byte
var chainBytesFile string
var chainInfo fs.FileInfo
switch teeType {
default:
return nil, WorkloadConfig{}, fmt.Errorf("don't know how to generate TeeData for TEE type %q", teeType)
case SEV, SEV_NO_ES:
// If we need a certificate chain, get it.
chain, err := os.CreateTemp(options.TempDir, "chain")
if err != nil {
return nil, WorkloadConfig{}, err
}
chain.Close()
defer func() {
if err := os.Remove(chain.Name()); err != nil {
logger.Warnf("error removing temporary file %q: %v", chain.Name(), err)
}
}()
logrus.Debugf("sevctl export -f %s", chain.Name())
cmd := exec.Command("sevctl", "export", "-f", chain.Name())
var stdout, stderr bytes.Buffer
cmd.Stdout, cmd.Stderr = &stdout, &stderr
if err := cmd.Run(); err != nil {
if !options.IgnoreAttestationErrors {
return nil, WorkloadConfig{}, chainRetrievalError{stderr.String(), err}
}
logger.Warn(chainRetrievalError{stderr.String(), err}.Error())
}
if chainBytes, err = os.ReadFile(chain.Name()); err != nil {
chainBytes = []byte{}
}
var teeData SevWorkloadData
if len(chainBytes) > 0 {
chainBytesFile = "sev.chain"
chainInfo, err = os.Stat(chain.Name())
if err != nil {
return nil, WorkloadConfig{}, err
}
teeData.VendorChain = "/" + chainBytesFile
}
encodedTeeData, err := json.Marshal(teeData)
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("encoding tee data: %w", err)
}
workloadConfig.TeeData = string(encodedTeeData)
case SNP:
teeData := SnpWorkloadData{
Generation: "milan",
}
encodedTeeData, err := json.Marshal(teeData)
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("encoding tee data: %w", err)
}
workloadConfig.TeeData = string(encodedTeeData)
}
// We're going to want to add some content to the rootfs, so set up an
// overlay that uses it as a lower layer so that we can write to it.
st, err := system.Stat(rootfsPath)
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("reading information about the container root filesystem: %w", err)
}
// Create a temporary directory to hold all of this. Use tmpdir.GetTempDir()
// instead of the passed-in location, which a crafty caller might have put in an
// overlay filesystem in storage because there tends to be more room there than
// in, say, /var/tmp, and the plaintext disk image, which we put in the passed-in
// location, can get quite large.
rootfsParentDir, err := os.MkdirTemp(tmpdir.GetTempDir(), "buildah-rootfs")
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("setting up parent for container root filesystem: %w", err)
}
defer func() {
if err := os.RemoveAll(rootfsParentDir); err != nil {
logger.Warnf("cleaning up parent for container root filesystem: %v", err)
}
}()
// Create a mountpoint for the new overlay, which we'll use as the rootfs.
rootfsDir := filepath.Join(rootfsParentDir, "rootfs")
if err := idtools.MkdirAndChown(rootfsDir, fs.FileMode(st.Mode()), idtools.IDPair{UID: int(st.UID()), GID: int(st.GID())}); err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("creating mount target for container root filesystem: %w", err)
}
defer func() {
if err := os.Remove(rootfsDir); err != nil {
logger.Warnf("removing mount target for container root filesystem: %v", err)
}
}()
// Create a directory to hold all of the overlay package's working state.
tempDir := filepath.Join(rootfsParentDir, "tmp")
if err = os.Mkdir(tempDir, 0o700); err != nil {
return nil, WorkloadConfig{}, err
}
// Create some working state in there.
overlayTempDir, err := overlay.TempDir(tempDir, int(st.UID()), int(st.GID()))
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("setting up mount of container root filesystem: %w", err)
}
defer func() {
if err := overlay.RemoveTemp(overlayTempDir); err != nil {
logger.Warnf("cleaning up mount of container root filesystem: %v", err)
}
}()
// Create a mount point using that working state.
rootfsMount, err := overlay.Mount(overlayTempDir, rootfsPath, rootfsDir, 0, 0, options.GraphOptions)
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("setting up support for overlay of container root filesystem: %w", err)
}
defer func() {
if err := overlay.Unmount(overlayTempDir); err != nil {
logger.Warnf("unmounting support for overlay of container root filesystem: %v", err)
}
}()
// Follow through on the overlay or bind mount, whatever the overlay package decided
// to leave to us to do.
rootfsMountOptions := strings.Join(rootfsMount.Options, ",")
logrus.Debugf("mounting %q to %q as %q with options %v", rootfsMount.Source, rootfsMount.Destination, rootfsMount.Type, rootfsMountOptions)
if err := mount.Mount(rootfsMount.Source, rootfsMount.Destination, rootfsMount.Type, rootfsMountOptions); err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("mounting overlay of container root filesystem: %w", err)
}
defer func() {
logrus.Debugf("unmounting %q", rootfsMount.Destination)
if err := mount.Unmount(rootfsMount.Destination); err != nil {
logger.Warnf("unmounting overlay of container root filesystem: %v", err)
}
}()
// Pretend that we didn't have to do any of the preceding.
rootfsPath = rootfsDir
// Write extra content to the rootfs, creating intermediate directories if necessary.
for location, content := range options.ExtraImageContent {
err := func() error {
if err := idtools.MkdirAllAndChownNew(filepath.Dir(filepath.Join(rootfsPath, location)), 0o755, idtools.IDPair{UID: int(st.UID()), GID: int(st.GID())}); err != nil {
return fmt.Errorf("ensuring %q is present in container root filesystem: %w", filepath.Dir(location), err)
}
output, err := os.OpenFile(filepath.Join(rootfsPath, location), os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o644)
if err != nil {
return fmt.Errorf("preparing to write %q to container root filesystem: %w", location, err)
}
defer output.Close()
input, err := os.Open(content)
if err != nil {
return err
}
defer input.Close()
if _, err := io.Copy(output, input); err != nil {
return fmt.Errorf("copying contents of %q to %q in container root filesystem: %w", content, location, err)
}
if err := output.Chown(int(st.UID()), int(st.GID())); err != nil {
return fmt.Errorf("setting owner of %q in the container root filesystem: %w", location, err)
}
if err := output.Chmod(0o644); err != nil {
return fmt.Errorf("setting permissions on %q in the container root filesystem: %w", location, err)
}
return nil
}()
if err != nil {
return nil, WorkloadConfig{}, err
}
}
// Write part of the config blob where the krun init process will be
// looking for it. The oci2cw tool used `buildah inspect` output, but
// init is just looking for fields that have the right names in any
// object, and the image's config will have that, so let's try encoding
// it directly.
krunConfigPath := filepath.Join(rootfsPath, ".krun_config.json")
krunConfigBytes, err := json.Marshal(ociConfig)
if err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("creating .krun_config from image configuration: %w", err)
}
if err := ioutils.AtomicWriteFile(krunConfigPath, krunConfigBytes, 0o600); err != nil {
return nil, WorkloadConfig{}, fmt.Errorf("saving krun config: %w", err)
}
// Encode the workload config, in case it fails for any reason.
cleanedUpWorkloadConfig := workloadConfig
switch cleanedUpWorkloadConfig.Type {
default:
return nil, WorkloadConfig{}, fmt.Errorf("don't know how to canonicalize TEE type %q", cleanedUpWorkloadConfig.Type)
case SEV, SEV_NO_ES:
cleanedUpWorkloadConfig.Type = SEV
case SNP:
cleanedUpWorkloadConfig.Type = SNP
}
workloadConfigBytes, err := json.Marshal(cleanedUpWorkloadConfig)
if err != nil {
return nil, WorkloadConfig{}, err
}
// Make sure we have the passphrase to use for encrypting the disk image.
diskEncryptionPassphrase := options.DiskEncryptionPassphrase
if diskEncryptionPassphrase == "" {
diskEncryptionPassphrase, err = GenerateDiskEncryptionPassphrase()
if err != nil {
return nil, WorkloadConfig{}, err
}
}
// If we weren't told how big the image should be, get a rough estimate
// of the input data size, then add a hedge to it.
imageSize := slop(options.ImageSize, options.Slop)
if imageSize == 0 {
var sourceSize int64
if err := filepath.WalkDir(rootfsPath, func(path string, d fs.DirEntry, err error) error {
if err != nil && !errors.Is(err, os.ErrNotExist) && !errors.Is(err, os.ErrPermission) {
return err
}
info, err := d.Info()
if err != nil && !errors.Is(err, os.ErrNotExist) && !errors.Is(err, os.ErrPermission) {
return err
}
sourceSize += info.Size()
return nil
}); err != nil {
return nil, WorkloadConfig{}, err
}
imageSize = slop(sourceSize, options.Slop)
}
if imageSize%4096 != 0 {
imageSize += (4096 - (imageSize % 4096))
}
if imageSize < minimumImageSize {
imageSize = minimumImageSize
}
// Create a file to use as the unencrypted version of the disk image.
plain, err := os.CreateTemp(options.TempDir, "plain.img")
if err != nil {
return nil, WorkloadConfig{}, err
}
removePlain := true
defer func() {
if removePlain {
if err := os.Remove(plain.Name()); err != nil {
logger.Warnf("removing temporary file %q: %v", plain.Name(), err)
}
}
}()
// Lengthen the plaintext disk image file.
if err := plain.Truncate(imageSize); err != nil {
plain.Close()
return nil, WorkloadConfig{}, err
}
plainInfo, err := plain.Stat()
plain.Close()
if err != nil {
return nil, WorkloadConfig{}, err
}
// Format the disk image with the filesystem contents.
if _, stderr, err := MakeFS(rootfsPath, plain.Name(), filesystem); err != nil {
if strings.TrimSpace(stderr) != "" {
return nil, WorkloadConfig{}, fmt.Errorf("%s: %w", strings.TrimSpace(stderr), err)
}
return nil, WorkloadConfig{}, err
}
// If we're registering the workload, we can do that now.
if workloadConfig.AttestationURL != "" {
if err := SendRegistrationRequest(workloadConfig, diskEncryptionPassphrase, options.FirmwareLibrary, options.IgnoreAttestationErrors, logger); err != nil {
return nil, WorkloadConfig{}, err
}
}
// Try to encrypt on the fly.
pipeReader, pipeWriter := io.Pipe()
removePlain = false
go func() {
var err error
defer func() {
if err := os.Remove(plain.Name()); err != nil {
logger.Warnf("removing temporary file %q: %v", plain.Name(), err)
}
if err != nil {
pipeWriter.CloseWithError(err)
} else {
pipeWriter.Close()
}
}()
plain, err := os.Open(plain.Name())
if err != nil {
logrus.Errorf("opening unencrypted disk image %q: %v", plain.Name(), err)
return
}
defer plain.Close()
tw := tar.NewWriter(pipeWriter)
defer tw.Flush()
// Write /entrypoint
var decompressedEntrypoint bytes.Buffer
decompressor, err := gzip.NewReader(bytes.NewReader(entrypointCompressedBytes))
if err != nil {
logrus.Errorf("decompressing copy of entrypoint: %v", err)
return
}
defer decompressor.Close()
if _, err = io.Copy(&decompressedEntrypoint, decompressor); err != nil {
logrus.Errorf("decompressing copy of entrypoint: %v", err)
return
}
entrypointHeader, err := tar.FileInfoHeader(plainInfo, "")
if err != nil {
logrus.Errorf("building header for entrypoint: %v", err)
return
}
entrypointHeader.Name = "entrypoint"
entrypointHeader.Mode = 0o755
entrypointHeader.Uname, entrypointHeader.Gname = "", ""
entrypointHeader.Uid, entrypointHeader.Gid = 0, 0
entrypointHeader.Size = int64(decompressedEntrypoint.Len())
if err = tw.WriteHeader(entrypointHeader); err != nil {
logrus.Errorf("writing header for %q: %v", entrypointHeader.Name, err)
return
}
if _, err = io.Copy(tw, &decompressedEntrypoint); err != nil {
logrus.Errorf("writing %q: %v", entrypointHeader.Name, err)
return
}
// Write /sev.chain
if chainInfo != nil {
chainHeader, err := tar.FileInfoHeader(chainInfo, "")
if err != nil {
logrus.Errorf("building header for %q: %v", chainInfo.Name(), err)
return
}
chainHeader.Name = chainBytesFile
chainHeader.Mode = 0o600
chainHeader.Uname, chainHeader.Gname = "", ""
chainHeader.Uid, chainHeader.Gid = 0, 0
chainHeader.Size = int64(len(chainBytes))
if err = tw.WriteHeader(chainHeader); err != nil {
logrus.Errorf("writing header for %q: %v", chainHeader.Name, err)
return
}
if _, err = tw.Write(chainBytes); err != nil {
logrus.Errorf("writing %q: %v", chainHeader.Name, err)
return
}
}
// Write /krun-sev.json.
workloadConfigHeader, err := tar.FileInfoHeader(plainInfo, "")
if err != nil {
logrus.Errorf("building header for %q: %v", plainInfo.Name(), err)
return
}
workloadConfigHeader.Name = "krun-sev.json"
workloadConfigHeader.Mode = 0o600
workloadConfigHeader.Uname, workloadConfigHeader.Gname = "", ""
workloadConfigHeader.Uid, workloadConfigHeader.Gid = 0, 0
workloadConfigHeader.Size = int64(len(workloadConfigBytes))
if err = tw.WriteHeader(workloadConfigHeader); err != nil {
logrus.Errorf("writing header for %q: %v", workloadConfigHeader.Name, err)
return
}
if _, err = tw.Write(workloadConfigBytes); err != nil {
logrus.Errorf("writing %q: %v", workloadConfigHeader.Name, err)
return
}
// Write /tmp.
tmpHeader, err := tar.FileInfoHeader(plainInfo, "")
if err != nil {
logrus.Errorf("building header for %q: %v", plainInfo.Name(), err)
return
}
tmpHeader.Name = "tmp/"
tmpHeader.Typeflag = tar.TypeDir
tmpHeader.Mode = 0o1777
tmpHeader.Uname, tmpHeader.Gname = "", ""
tmpHeader.Uid, tmpHeader.Gid = 0, 0
tmpHeader.Size = 0
if err = tw.WriteHeader(tmpHeader); err != nil {
logrus.Errorf("writing header for %q: %v", tmpHeader.Name, err)
return
}
// Now figure out the footer that we'll append to the encrypted disk.
var footer bytes.Buffer
lengthBuffer := make([]byte, 8)
footer.Write(workloadConfigBytes)
footer.WriteString("KRUN")
binary.LittleEndian.PutUint64(lengthBuffer, uint64(len(workloadConfigBytes)))
footer.Write(lengthBuffer)
// Start encrypting and write /disk.img.
header, encrypt, blockSize, err := luksy.EncryptV1([]string{diskEncryptionPassphrase}, "")
paddingBoundary := int64(4096)
paddingNeeded := (paddingBoundary - ((int64(len(header)) + imageSize + int64(footer.Len())) % paddingBoundary)) % paddingBoundary
diskHeader := workloadConfigHeader
diskHeader.Name = "disk.img"
diskHeader.Mode = 0o600
diskHeader.Size = int64(len(header)) + imageSize + paddingNeeded + int64(footer.Len())
if err = tw.WriteHeader(diskHeader); err != nil {
logrus.Errorf("writing archive header for disk.img: %v", err)
return
}
if _, err = io.Copy(tw, bytes.NewReader(header)); err != nil {
logrus.Errorf("writing encryption header for disk.img: %v", err)
return
}
encryptWrapper := luksy.EncryptWriter(encrypt, tw, blockSize)
if _, err = io.Copy(encryptWrapper, plain); err != nil {
logrus.Errorf("encrypting disk.img: %v", err)
return
}
encryptWrapper.Close()
if _, err = tw.Write(make([]byte, paddingNeeded)); err != nil {
logrus.Errorf("writing padding for disk.img: %v", err)
return
}
if _, err = io.Copy(tw, &footer); err != nil {
logrus.Errorf("writing footer for disk.img: %v", err)
return
}
tw.Close()
}()
return pipeReader, workloadConfig, nil
}
func slop(size int64, slop string) int64 {
if slop == "" {
return size * 5 / 4
}
for _, factor := range strings.Split(slop, "+") {
factor = strings.TrimSpace(factor)
if factor == "" {
continue
}
if strings.HasSuffix(factor, "%") {
percentage := strings.TrimSuffix(factor, "%")
percent, err := strconv.ParseInt(percentage, 10, 8)
if err != nil {
logrus.Warnf("parsing percentage %q: %v", factor, err)
} else {
size *= (percent + 100)
size /= 100
}
} else {
more, err := units.RAMInBytes(factor)
if err != nil {
logrus.Warnf("parsing %q as a size: %v", factor, err)
} else {
size += more
}
}
}
return size
}