diff --git a/pkg/archive/archive.go b/pkg/archive/archive.go index 783905f718..ebe55eddc2 100644 --- a/pkg/archive/archive.go +++ b/pkg/archive/archive.go @@ -31,6 +31,18 @@ import ( exec "golang.org/x/sys/execabs" ) +// ImpliedDirectoryMode represents the mode (Unix permissions) applied to directories that are implied by files in a +// tar, but that do not have their own header entry. +// +// The permissions mask is stored in a constant instead of locally to ensure that magic numbers do not +// proliferate in the codebase. The default value 0755 has been selected based on the default umask of 0022, and +// a convention of mkdir(1) calling mkdir(2) with permissions of 0777, resulting in a final value of 0755. +// +// This value is currently implementation-defined, and not captured in any cross-runtime specification. Thus, it is +// subject to change in Moby at any time -- image authors who require consistent or known directory permissions +// should explicitly control them by ensuring that header entries exist for any applicable path. +const ImpliedDirectoryMode = 0755 + type ( // Compression is the state represents if compressed or not. Compression int @@ -810,7 +822,6 @@ func Tar(path string, compression Compression) (io.ReadCloser, error) { // TarWithOptions creates an archive from the directory at `path`, only including files whose relative // paths are included in `options.IncludeFiles` (if non-nil) or not in `options.ExcludePatterns`. func TarWithOptions(srcPath string, options *TarOptions) (io.ReadCloser, error) { - // Fix the source path to work with long path names. This is a no-op // on platforms other than Windows. srcPath = fixVolumePathPrefix(srcPath) @@ -1018,7 +1029,6 @@ func Unpack(decompressedArchive io.Reader, dest string, options *TarOptions) err defer pools.BufioReader32KPool.Put(trBuf) var dirs []*tar.Header - rootIDs := options.IDMap.RootPair() whiteoutConverter, err := getWhiteoutConverter(options.WhiteoutFormat, options.InUserNS) if err != nil { return err @@ -1053,19 +1063,10 @@ loop: } } - // After calling filepath.Clean(hdr.Name) above, hdr.Name will now be in - // the filepath format for the OS on which the daemon is running. Hence - // the check for a slash-suffix MUST be done in an OS-agnostic way. - if !strings.HasSuffix(hdr.Name, string(os.PathSeparator)) { - // Not the root directory, ensure that the parent directory exists - parent := filepath.Dir(hdr.Name) - parentPath := filepath.Join(dest, parent) - if _, err := os.Lstat(parentPath); err != nil && os.IsNotExist(err) { - err = idtools.MkdirAllAndChownNew(parentPath, 0755, rootIDs) - if err != nil { - return err - } - } + // Ensure that the parent directory exists. + err = createImpliedDirectories(dest, hdr, options) + if err != nil { + return err } // #nosec G305 -- The joined path is checked for path traversal. @@ -1143,6 +1144,35 @@ loop: return nil } +// createImpliedDirectories will create all parent directories of the current path with default permissions, if they do +// not already exist. This is possible as the tar format supports 'implicit' directories, where their existence is +// defined by the paths of files in the tar, but there are no header entries for the directories themselves, and thus +// we most both create them and choose metadata like permissions. +// +// The caller should have performed filepath.Clean(hdr.Name), so hdr.Name will now be in the filepath format for the OS +// on which the daemon is running. This precondition is required because this function assumes a OS-specific path +// separator when checking that a path is not the root. +func createImpliedDirectories(dest string, hdr *tar.Header, options *TarOptions) error { + // Not the root directory, ensure that the parent directory exists + if !strings.HasSuffix(hdr.Name, string(os.PathSeparator)) { + parent := filepath.Dir(hdr.Name) + parentPath := filepath.Join(dest, parent) + if _, err := os.Lstat(parentPath); err != nil && os.IsNotExist(err) { + // RootPair() is confined inside this loop as most cases will not require a call, so we can spend some + // unneeded function calls in the uncommon case to encapsulate logic -- implied directories are a niche + // usage that reduces the portability of an image. + rootIDs := options.IDMap.RootPair() + + err = idtools.MkdirAllAndChownNew(parentPath, ImpliedDirectoryMode, rootIDs) + if err != nil { + return err + } + } + } + + return nil +} + // Untar reads a stream of bytes from `archive`, parses it as a tar archive, // and unpacks it into the directory at `dest`. // The archive may be compressed with one of the following algorithms: diff --git a/pkg/archive/diff.go b/pkg/archive/diff.go index f83d126faf..62409d827e 100644 --- a/pkg/archive/diff.go +++ b/pkg/archive/diff.go @@ -72,20 +72,10 @@ func UnpackLayer(dest string, layer io.Reader, options *TarOptions) (size int64, } } - // Note as these operations are platform specific, so must the slash be. - if !strings.HasSuffix(hdr.Name, string(os.PathSeparator)) { - // Not the root directory, ensure that the parent directory exists. - // This happened in some tests where an image had a tarfile without any - // parent directories. - parent := filepath.Dir(hdr.Name) - parentPath := filepath.Join(dest, parent) - - if _, err := os.Lstat(parentPath); err != nil && os.IsNotExist(err) { - err = system.MkdirAll(parentPath, 0600) - if err != nil { - return 0, err - } - } + // Ensure that the parent directory exists. + err = createImpliedDirectories(dest, hdr, options) + if err != nil { + return 0, err } // Skip AUFS metadata dirs