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3029e765e2
Previously only unpack operations were supported with chroot. This adds chroot support for packing operations. This prevents potential breakouts when copying data from a container. Signed-off-by: Brian Goff <cpuguy83@gmail.com>
97 lines
3.2 KiB
Go
97 lines
3.2 KiB
Go
package chrootarchive // import "github.com/docker/docker/pkg/chrootarchive"
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import (
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"github.com/docker/docker/pkg/archive"
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"github.com/docker/docker/pkg/idtools"
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)
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// NewArchiver returns a new Archiver which uses chrootarchive.Untar
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func NewArchiver(idMapping *idtools.IdentityMapping) *archive.Archiver {
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if idMapping == nil {
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idMapping = &idtools.IdentityMapping{}
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}
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return &archive.Archiver{
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Untar: Untar,
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IDMapping: idMapping,
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}
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}
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// Untar reads a stream of bytes from `archive`, parses it as a tar archive,
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// and unpacks it into the directory at `dest`.
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// The archive may be compressed with one of the following algorithms:
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// identity (uncompressed), gzip, bzip2, xz.
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func Untar(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
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return untarHandler(tarArchive, dest, options, true, dest)
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}
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// UntarWithRoot is the same as `Untar`, but allows you to pass in a root directory
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// The root directory is the directory that will be chrooted to.
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// `dest` must be a path within `root`, if it is not an error will be returned.
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//
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// `root` should set to a directory which is not controlled by any potentially
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// malicious process.
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//
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// This should be used to prevent a potential attacker from manipulating `dest`
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// such that it would provide access to files outside of `dest` through things
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// like symlinks. Normally `ResolveSymlinksInScope` would handle this, however
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// sanitizing symlinks in this manner is inherrently racey:
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// ref: CVE-2018-15664
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func UntarWithRoot(tarArchive io.Reader, dest string, options *archive.TarOptions, root string) error {
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return untarHandler(tarArchive, dest, options, true, root)
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}
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// UntarUncompressed reads a stream of bytes from `archive`, parses it as a tar archive,
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// and unpacks it into the directory at `dest`.
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// The archive must be an uncompressed stream.
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func UntarUncompressed(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
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return untarHandler(tarArchive, dest, options, false, dest)
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}
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// Handler for teasing out the automatic decompression
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func untarHandler(tarArchive io.Reader, dest string, options *archive.TarOptions, decompress bool, root string) error {
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if tarArchive == nil {
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return fmt.Errorf("Empty archive")
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}
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if options == nil {
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options = &archive.TarOptions{}
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}
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if options.ExcludePatterns == nil {
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options.ExcludePatterns = []string{}
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}
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idMapping := idtools.NewIDMappingsFromMaps(options.UIDMaps, options.GIDMaps)
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rootIDs := idMapping.RootPair()
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dest = filepath.Clean(dest)
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if _, err := os.Stat(dest); os.IsNotExist(err) {
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if err := idtools.MkdirAllAndChownNew(dest, 0755, rootIDs); err != nil {
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return err
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}
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}
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r := ioutil.NopCloser(tarArchive)
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if decompress {
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decompressedArchive, err := archive.DecompressStream(tarArchive)
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if err != nil {
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return err
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}
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defer decompressedArchive.Close()
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r = decompressedArchive
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}
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return invokeUnpack(r, dest, options, root)
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}
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// Tar tars the requested path while chrooted to the specified root.
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func Tar(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
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if options == nil {
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options = &archive.TarOptions{}
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}
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return invokePack(srcPath, options, root)
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}
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