github.com/rish1988/moby@v25.0.2+incompatible/pkg/chrootarchive/archive.go (about)

     1  package chrootarchive // import "github.com/docker/docker/pkg/chrootarchive"
     2  
     3  import (
     4  	"fmt"
     5  	"io"
     6  	"os"
     7  	"path/filepath"
     8  
     9  	"github.com/docker/docker/pkg/archive"
    10  	"github.com/docker/docker/pkg/idtools"
    11  )
    12  
    13  // NewArchiver returns a new Archiver which uses chrootarchive.Untar
    14  func NewArchiver(idMapping idtools.IdentityMapping) *archive.Archiver {
    15  	return &archive.Archiver{
    16  		Untar:     Untar,
    17  		IDMapping: idMapping,
    18  	}
    19  }
    20  
    21  // Untar reads a stream of bytes from `archive`, parses it as a tar archive,
    22  // and unpacks it into the directory at `dest`.
    23  // The archive may be compressed with one of the following algorithms:
    24  // identity (uncompressed), gzip, bzip2, xz.
    25  func Untar(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
    26  	return untarHandler(tarArchive, dest, options, true, dest)
    27  }
    28  
    29  // UntarWithRoot is the same as `Untar`, but allows you to pass in a root directory
    30  // The root directory is the directory that will be chrooted to.
    31  // `dest` must be a path within `root`, if it is not an error will be returned.
    32  //
    33  // `root` should set to a directory which is not controlled by any potentially
    34  // malicious process.
    35  //
    36  // This should be used to prevent a potential attacker from manipulating `dest`
    37  // such that it would provide access to files outside of `dest` through things
    38  // like symlinks. Normally `ResolveSymlinksInScope` would handle this, however
    39  // sanitizing symlinks in this manner is inherrently racey:
    40  // ref: CVE-2018-15664
    41  func UntarWithRoot(tarArchive io.Reader, dest string, options *archive.TarOptions, root string) error {
    42  	return untarHandler(tarArchive, dest, options, true, root)
    43  }
    44  
    45  // UntarUncompressed reads a stream of bytes from `archive`, parses it as a tar archive,
    46  // and unpacks it into the directory at `dest`.
    47  // The archive must be an uncompressed stream.
    48  func UntarUncompressed(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
    49  	return untarHandler(tarArchive, dest, options, false, dest)
    50  }
    51  
    52  // Handler for teasing out the automatic decompression
    53  func untarHandler(tarArchive io.Reader, dest string, options *archive.TarOptions, decompress bool, root string) error {
    54  	if tarArchive == nil {
    55  		return fmt.Errorf("Empty archive")
    56  	}
    57  	if options == nil {
    58  		options = &archive.TarOptions{}
    59  	}
    60  	if options.ExcludePatterns == nil {
    61  		options.ExcludePatterns = []string{}
    62  	}
    63  
    64  	// If dest is inside a root then directory is created within chroot by extractor.
    65  	// This case is only currently used by cp.
    66  	if dest == root {
    67  		rootIDs := options.IDMap.RootPair()
    68  
    69  		dest = filepath.Clean(dest)
    70  		if _, err := os.Stat(dest); os.IsNotExist(err) {
    71  			if err := idtools.MkdirAllAndChownNew(dest, 0o755, rootIDs); err != nil {
    72  				return err
    73  			}
    74  		}
    75  	}
    76  
    77  	r := io.NopCloser(tarArchive)
    78  	if decompress {
    79  		decompressedArchive, err := archive.DecompressStream(tarArchive)
    80  		if err != nil {
    81  			return err
    82  		}
    83  		defer decompressedArchive.Close()
    84  		r = decompressedArchive
    85  	}
    86  
    87  	return invokeUnpack(r, dest, options, root)
    88  }
    89  
    90  // Tar tars the requested path while chrooted to the specified root.
    91  func Tar(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
    92  	if options == nil {
    93  		options = &archive.TarOptions{}
    94  	}
    95  	return invokePack(srcPath, options, root)
    96  }