driver: use stdlib tar for docker-container config files #3996
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,127 @@ | ||
| package docker | ||
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| import ( | ||
| "archive/tar" | ||
| "bytes" | ||
| "io" | ||
| "io/fs" | ||
| "maps" | ||
| "path" | ||
| "slices" | ||
| "strings" | ||
|
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| "github.com/docker/buildx/util/confutil" | ||
| "github.com/pkg/errors" | ||
| ) | ||
|
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| const ( | ||
| tarDirMode int64 = 0o755 | ||
| tarFileMode int64 = 0o644 | ||
| ) | ||
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| type configTarEntry struct { | ||
| name string | ||
| data []byte | ||
| } | ||
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| func tarConfigFiles(files map[string][]byte) (io.ReadCloser, error) { | ||
| entries, dirs, err := configTarEntries(path.Base(confutil.DefaultBuildKitConfigDir), files) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| var buf bytes.Buffer | ||
| tw := tar.NewWriter(&buf) | ||
| if err := writeConfigTar(tw, dirs, entries); err != nil { | ||
| _ = tw.Close() | ||
| return nil, err | ||
| } | ||
| if err := tw.Close(); err != nil { | ||
| return nil, err | ||
| } | ||
| return io.NopCloser(bytes.NewReader(buf.Bytes())), nil | ||
| } | ||
|
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| func configTarEntries(configDir string, files map[string][]byte) ([]configTarEntry, []string, error) { | ||
| configDir, err := configArchiveRoot(configDir) | ||
| if err != nil { | ||
| return nil, nil, err | ||
| } | ||
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| entries := make([]configTarEntry, 0, len(files)) | ||
| dirs := map[string]struct{}{} | ||
| filePaths := make(map[string]struct{}, len(files)) | ||
| if len(files) > 0 { | ||
| dirs[configDir] = struct{}{} | ||
| } | ||
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| for _, name := range slices.Sorted(maps.Keys(files)) { | ||
| archivePath, err := configArchivePath(configDir, name) | ||
| if err != nil { | ||
| return nil, nil, err | ||
| } | ||
| entries = append(entries, configTarEntry{ | ||
| name: archivePath, | ||
| data: files[name], | ||
| }) | ||
| filePaths[archivePath] = struct{}{} | ||
| for dir := path.Dir(archivePath); dir != "."; dir = path.Dir(dir) { | ||
| dirs[dir] = struct{}{} | ||
| } | ||
| } | ||
|
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| for filePath := range filePaths { | ||
| if _, ok := dirs[filePath]; ok { | ||
| return nil, nil, errors.Errorf("config file path %q conflicts with directory", strings.TrimPrefix(filePath, configDir+"/")) | ||
| } | ||
| } | ||
|
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| return entries, slices.Sorted(maps.Keys(dirs)), nil | ||
| } | ||
|
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| func configArchiveRoot(name string) (string, error) { | ||
| if name == "." || strings.Contains(name, "/") || strings.Contains(name, `\`) || strings.ContainsRune(name, 0) || !fs.ValidPath(name) { | ||
| return "", errors.Errorf("invalid config archive root %q", name) | ||
| } | ||
| return name, nil | ||
| } | ||
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| func configArchivePath(configDir, name string) (string, error) { | ||
| if strings.Contains(name, `\`) || strings.ContainsRune(name, 0) { | ||
| return "", errors.Errorf("invalid config file path %q", name) | ||
| } | ||
| // Validate the literal slash path. path.Join would clean traversal first. | ||
| archivePath := configDir + "/" + name | ||
| if !fs.ValidPath(archivePath) { | ||
| return "", errors.Errorf("invalid config file path %q", name) | ||
| } | ||
| return archivePath, nil | ||
| } | ||
|
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| func writeConfigTar(tw *tar.Writer, dirs []string, entries []configTarEntry) error { | ||
| for _, dir := range dirs { | ||
| if err := tw.WriteHeader(&tar.Header{ | ||
|
There was a problem hiding this comment. Should we force a format format here? I think Go should select the appropriate one, but something to potentially be aware of.
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Author
There was a problem hiding this comment. I think leaving |
||
| Name: dir + "/", | ||
| Typeflag: tar.TypeDir, | ||
| Mode: tarDirMode, | ||
| }); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| for _, entry := range entries { | ||
| if err := tw.WriteHeader(&tar.Header{ | ||
| Name: entry.name, | ||
| Typeflag: tar.TypeReg, | ||
| Mode: tarFileMode, | ||
| Size: int64(len(entry.data)), | ||
| }); err != nil { | ||
| return err | ||
| } | ||
| if len(entry.data) == 0 { | ||
| continue | ||
| } | ||
| if _, err := tw.Write(entry.data); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,161 @@ | ||
| package docker | ||
|
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| import ( | ||
| "archive/tar" | ||
| "io" | ||
| "testing" | ||
|
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| "github.com/stretchr/testify/require" | ||
| ) | ||
|
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| type tarEntry struct { | ||
| header *tar.Header | ||
| body []byte | ||
| } | ||
|
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| func TestTarConfigFiles(t *testing.T) { | ||
| files := map[string][]byte{ | ||
| "buildkitd.toml": []byte("debug = true\n"), | ||
| "certs/example.com/ca.pem": []byte("certificate"), | ||
| } | ||
|
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| rc, err := tarConfigFiles(files) | ||
| require.NoError(t, err) | ||
| defer rc.Close() | ||
|
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| expected := []string{ | ||
| "buildkit/", | ||
| "buildkit/certs/", | ||
| "buildkit/certs/example.com/", | ||
| "buildkit/buildkitd.toml", | ||
| "buildkit/certs/example.com/ca.pem", | ||
| } | ||
| entries, names := readTarEntries(t, rc) | ||
| require.Equal(t, expected, names) | ||
| require.Len(t, entries, len(expected)) | ||
| for _, name := range expected { | ||
| entry, ok := entries[name] | ||
| require.Truef(t, ok, "missing archive entry %q", name) | ||
| require.Equal(t, 0, entry.header.Uid) | ||
| require.Equal(t, 0, entry.header.Gid) | ||
| require.Empty(t, entry.header.Uname) | ||
| require.Empty(t, entry.header.Gname) | ||
| } | ||
|
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| require.Equal(t, byte(tar.TypeDir), entries["buildkit/"].header.Typeflag) | ||
| require.Equal(t, tarDirMode, entries["buildkit/"].header.Mode) | ||
| require.Equal(t, files["buildkitd.toml"], entries["buildkit/buildkitd.toml"].body) | ||
| require.Equal(t, tarFileMode, entries["buildkit/buildkitd.toml"].header.Mode) | ||
| require.Equal(t, files["certs/example.com/ca.pem"], entries["buildkit/certs/example.com/ca.pem"].body) | ||
| } | ||
|
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| func TestTarConfigFilesSnapshotsContent(t *testing.T) { | ||
| files := map[string][]byte{ | ||
| "buildkitd.toml": []byte("debug = true\n"), | ||
| } | ||
|
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| rc, err := tarConfigFiles(files) | ||
| require.NoError(t, err) | ||
| defer rc.Close() | ||
|
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| files["buildkitd.toml"][0] = '#' | ||
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| entries, _ := readTarEntries(t, rc) | ||
| require.Equal(t, []byte("debug = true\n"), entries["buildkit/buildkitd.toml"].body) | ||
| } | ||
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| func TestTarConfigFilesEmpty(t *testing.T) { | ||
| rc, err := tarConfigFiles(nil) | ||
| require.NoError(t, err) | ||
| defer rc.Close() | ||
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| tr := tar.NewReader(rc) | ||
| _, err = tr.Next() | ||
| require.ErrorIs(t, err, io.EOF) | ||
| } | ||
|
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| func TestTarConfigFilesRejectsInvalidPaths(t *testing.T) { | ||
| for _, tc := range []struct { | ||
| name string | ||
| path string | ||
| }{ | ||
| {name: "empty", path: ""}, | ||
| {name: "dot", path: "."}, | ||
| {name: "leading-dot", path: "./buildkitd.toml"}, | ||
| {name: "parent", path: "../buildkitd.toml"}, | ||
| {name: "absolute", path: "/buildkitd.toml"}, | ||
| {name: "trailing-slash", path: "certs/"}, | ||
| {name: "parent-element", path: "certs/../ca.pem"}, | ||
| {name: "dot-element", path: "certs/./ca.pem"}, | ||
| {name: "empty-element", path: "certs//ca.pem"}, | ||
| {name: "backslash", path: `certs\ca.pem`}, | ||
| {name: "nul", path: "certs/ca\x00.pem"}, | ||
| } { | ||
| t.Run(tc.name, func(t *testing.T) { | ||
| rc, err := tarConfigFiles(map[string][]byte{ | ||
| tc.path: []byte("invalid"), | ||
| }) | ||
| require.Error(t, err) | ||
| require.Contains(t, err.Error(), "invalid config file path") | ||
| require.Nil(t, rc) | ||
| }) | ||
| } | ||
| } | ||
|
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| func TestTarConfigFilesRejectsFileDirectoryConflict(t *testing.T) { | ||
| rc, err := tarConfigFiles(map[string][]byte{ | ||
| "certs": []byte("file"), | ||
| "certs/ca.pem": []byte("ca"), | ||
| }) | ||
| require.Error(t, err) | ||
| require.Contains(t, err.Error(), "conflicts with directory") | ||
| require.Nil(t, rc) | ||
| } | ||
|
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| func TestConfigTarEntriesRejectsInvalidRoot(t *testing.T) { | ||
| for _, tc := range []struct { | ||
| name string | ||
| root string | ||
| }{ | ||
| {name: "empty", root: ""}, | ||
| {name: "dot", root: "."}, | ||
| {name: "parent", root: "../buildkit"}, | ||
| {name: "absolute", root: "/buildkit"}, | ||
| {name: "nested", root: "etc/buildkit"}, | ||
| {name: "backslash", root: `etc\buildkit`}, | ||
| {name: "nul", root: "build\x00kit"}, | ||
| } { | ||
| t.Run(tc.name, func(t *testing.T) { | ||
| entries, dirs, err := configTarEntries(tc.root, map[string][]byte{ | ||
| "buildkitd.toml": []byte("debug = true\n"), | ||
| }) | ||
| require.Error(t, err) | ||
| require.Contains(t, err.Error(), "invalid config archive root") | ||
| require.Nil(t, entries) | ||
| require.Nil(t, dirs) | ||
| }) | ||
| } | ||
| } | ||
|
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| func readTarEntries(t *testing.T, r io.Reader) (map[string]tarEntry, []string) { | ||
| t.Helper() | ||
|
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| tr := tar.NewReader(r) | ||
| entries := map[string]tarEntry{} | ||
| var names []string | ||
| for { | ||
| hdr, err := tr.Next() | ||
| if err == io.EOF { | ||
| break | ||
| } | ||
| require.NoError(t, err) | ||
| names = append(names, hdr.Name) | ||
| body, err := io.ReadAll(tr) | ||
| require.NoError(t, err) | ||
| entries[hdr.Name] = tarEntry{ | ||
| header: new(*hdr), | ||
| body: body, | ||
| } | ||
| } | ||
| return entries, names | ||
| } |
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configDir is the only name reaching writeConfigTar without passing configArchivePath. It's safe today only because len(files) > 0 makes it a prefix of every validated path. Would it be worth asserting it explicitly as well?
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Yeah, fair point.
configDiris currently derived frompath.Base(confutil.DefaultBuildKitConfigDir), so it'sbuildkittoday, but it's still the one path component added to the archive before going through the same explicit validation path. I will tighten that so the archive root is validated too, or refactor it so we don't pass an arbitrary root string around.