github.com/rentongzhang/docker@v1.8.2-rc1/pkg/archive/utils_test.go (about)

     1  package archive
     2  
     3  import (
     4  	"archive/tar"
     5  	"bytes"
     6  	"fmt"
     7  	"io"
     8  	"io/ioutil"
     9  	"os"
    10  	"path/filepath"
    11  	"time"
    12  )
    13  
    14  var testUntarFns = map[string]func(string, io.Reader) error{
    15  	"untar": func(dest string, r io.Reader) error {
    16  		return Untar(r, dest, nil)
    17  	},
    18  	"applylayer": func(dest string, r io.Reader) error {
    19  		_, err := ApplyLayer(dest, ArchiveReader(r))
    20  		return err
    21  	},
    22  }
    23  
    24  // testBreakout is a helper function that, within the provided `tmpdir` directory,
    25  // creates a `victim` folder with a generated `hello` file in it.
    26  // `untar` extracts to a directory named `dest`, the tar file created from `headers`.
    27  //
    28  // Here are the tested scenarios:
    29  // - removed `victim` folder				(write)
    30  // - removed files from `victim` folder			(write)
    31  // - new files in `victim` folder			(write)
    32  // - modified files in `victim` folder			(write)
    33  // - file in `dest` with same content as `victim/hello` (read)
    34  //
    35  // When using testBreakout make sure you cover one of the scenarios listed above.
    36  func testBreakout(untarFn string, tmpdir string, headers []*tar.Header) error {
    37  	tmpdir, err := ioutil.TempDir("", tmpdir)
    38  	if err != nil {
    39  		return err
    40  	}
    41  	defer os.RemoveAll(tmpdir)
    42  
    43  	dest := filepath.Join(tmpdir, "dest")
    44  	if err := os.Mkdir(dest, 0755); err != nil {
    45  		return err
    46  	}
    47  
    48  	victim := filepath.Join(tmpdir, "victim")
    49  	if err := os.Mkdir(victim, 0755); err != nil {
    50  		return err
    51  	}
    52  	hello := filepath.Join(victim, "hello")
    53  	helloData, err := time.Now().MarshalText()
    54  	if err != nil {
    55  		return err
    56  	}
    57  	if err := ioutil.WriteFile(hello, helloData, 0644); err != nil {
    58  		return err
    59  	}
    60  	helloStat, err := os.Stat(hello)
    61  	if err != nil {
    62  		return err
    63  	}
    64  
    65  	reader, writer := io.Pipe()
    66  	go func() {
    67  		t := tar.NewWriter(writer)
    68  		for _, hdr := range headers {
    69  			t.WriteHeader(hdr)
    70  		}
    71  		t.Close()
    72  	}()
    73  
    74  	untar := testUntarFns[untarFn]
    75  	if untar == nil {
    76  		return fmt.Errorf("could not find untar function %q in testUntarFns", untarFn)
    77  	}
    78  	if err := untar(dest, reader); err != nil {
    79  		if _, ok := err.(breakoutError); !ok {
    80  			// If untar returns an error unrelated to an archive breakout,
    81  			// then consider this an unexpected error and abort.
    82  			return err
    83  		}
    84  		// Here, untar detected the breakout.
    85  		// Let's move on verifying that indeed there was no breakout.
    86  		fmt.Printf("breakoutError: %v\n", err)
    87  	}
    88  
    89  	// Check victim folder
    90  	f, err := os.Open(victim)
    91  	if err != nil {
    92  		// codepath taken if victim folder was removed
    93  		return fmt.Errorf("archive breakout: error reading %q: %v", victim, err)
    94  	}
    95  	defer f.Close()
    96  
    97  	// Check contents of victim folder
    98  	//
    99  	// We are only interested in getting 2 files from the victim folder, because if all is well
   100  	// we expect only one result, the `hello` file. If there is a second result, it cannot
   101  	// hold the same name `hello` and we assume that a new file got created in the victim folder.
   102  	// That is enough to detect an archive breakout.
   103  	names, err := f.Readdirnames(2)
   104  	if err != nil {
   105  		// codepath taken if victim is not a folder
   106  		return fmt.Errorf("archive breakout: error reading directory content of %q: %v", victim, err)
   107  	}
   108  	for _, name := range names {
   109  		if name != "hello" {
   110  			// codepath taken if new file was created in victim folder
   111  			return fmt.Errorf("archive breakout: new file %q", name)
   112  		}
   113  	}
   114  
   115  	// Check victim/hello
   116  	f, err = os.Open(hello)
   117  	if err != nil {
   118  		// codepath taken if read permissions were removed
   119  		return fmt.Errorf("archive breakout: could not lstat %q: %v", hello, err)
   120  	}
   121  	defer f.Close()
   122  	b, err := ioutil.ReadAll(f)
   123  	if err != nil {
   124  		return err
   125  	}
   126  	fi, err := f.Stat()
   127  	if err != nil {
   128  		return err
   129  	}
   130  	if helloStat.IsDir() != fi.IsDir() ||
   131  		// TODO: cannot check for fi.ModTime() change
   132  		helloStat.Mode() != fi.Mode() ||
   133  		helloStat.Size() != fi.Size() ||
   134  		!bytes.Equal(helloData, b) {
   135  		// codepath taken if hello has been modified
   136  		return fmt.Errorf("archive breakout: file %q has been modified. Contents: expected=%q, got=%q. FileInfo: expected=%#v, got=%#v", hello, helloData, b, helloStat, fi)
   137  	}
   138  
   139  	// Check that nothing in dest/ has the same content as victim/hello.
   140  	// Since victim/hello was generated with time.Now(), it is safe to assume
   141  	// that any file whose content matches exactly victim/hello, managed somehow
   142  	// to access victim/hello.
   143  	return filepath.Walk(dest, func(path string, info os.FileInfo, err error) error {
   144  		if info.IsDir() {
   145  			if err != nil {
   146  				// skip directory if error
   147  				return filepath.SkipDir
   148  			}
   149  			// enter directory
   150  			return nil
   151  		}
   152  		if err != nil {
   153  			// skip file if error
   154  			return nil
   155  		}
   156  		b, err := ioutil.ReadFile(path)
   157  		if err != nil {
   158  			// Houston, we have a problem. Aborting (space)walk.
   159  			return err
   160  		}
   161  		if bytes.Equal(helloData, b) {
   162  			return fmt.Errorf("archive breakout: file %q has been accessed via %q", hello, path)
   163  		}
   164  		return nil
   165  	})
   166  }