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Potential fix for code scanning alert no. 2389: Arbitrary file access during archive extraction ("Zip Slip") #6250

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Potential fix for code scanning alert no. 2389: Arbitrary file access during archive extraction ("Zip Slip") #6250

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43 changes: 32 additions & 11 deletions evetest/utils/tar.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
"io"
"os"
"path"
"strings"
)

// MaxDecompressedContentSize is the maximum size of a file that can be written to disk after decompression.
Expand All @@ -18,9 +19,21 @@

// ExtractFromTar extracts files from a tar reader into the destination directory
func ExtractFromTar(u io.Reader, destination string) error {
// path inside tar is relative
pathBuilder := func(oldPath string) string {
return path.Join(destination, oldPath)
cleanDestination := path.Clean(destination)
// path inside tar must remain relative and contained within destination
safePath := func(oldPath string) (string, error) {
if oldPath == "" {
return "", fmt.Errorf("empty archive path")
}

Check failure

Code scanning / CodeQL

Arbitrary file access during archive extraction ("Zip Slip") High

Unsanitized archive entry, which may contain '..', is used in a
file system operation
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.
Unsanitized archive entry, which may contain '..', is used in a
file system operation
Loading
.
Unsanitized archive entry, which may contain '..', is used in a
file system operation
Loading
.
Unsanitized archive entry, which may contain '..', is used in a
file system operation
Loading
.
Unsanitized archive entry, which may contain '..', is used in a
file system operation
Loading
.
Unsanitized archive entry, which may contain '..', is used in a
file system operation
Loading
.
cleanOldPath := path.Clean(oldPath)
if cleanOldPath == "." || strings.HasPrefix(cleanOldPath, "..") || strings.Contains(cleanOldPath, "/..") || path.IsAbs(cleanOldPath) {
return "", fmt.Errorf("invalid archive path: %s", oldPath)
}
fullPath := path.Clean(path.Join(cleanDestination, cleanOldPath))
if fullPath != cleanDestination && !strings.HasPrefix(fullPath, cleanDestination+"/") {
return "", fmt.Errorf("archive path escapes destination: %s", oldPath)
}
return fullPath, nil
}
tarReader := tar.NewReader(u)
for {
Expand All @@ -31,19 +44,23 @@
if err != nil {
return fmt.Errorf("ExtractFromTar: Next() failed: %w", err)
}
entryPath, err := safePath(header.Name)

Check failure

Code scanning / CodeQL

Arbitrary file write extracting an archive containing symbolic links High

Unresolved path from an archive header, which may point outside the archive root, is used in
symlink creation
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.
if err != nil {
return fmt.Errorf("ExtractFromTar: invalid entry name %q: %w", header.Name, err)
}
switch header.Typeflag {
case tar.TypeDir:
if err := os.MkdirAll(pathBuilder(header.Name), os.FileMode(header.Mode)); err != nil {
if err := os.MkdirAll(entryPath, os.FileMode(header.Mode)); err != nil {
return fmt.Errorf("ExtractFromTar: Mkdir() failed: %w", err)
}
case tar.TypeReg:
if _, err := os.Lstat(pathBuilder(header.Name)); err == nil {
err = os.Remove(pathBuilder(header.Name))
if _, err := os.Lstat(entryPath); err == nil {
err = os.Remove(entryPath)
if err != nil {
return fmt.Errorf("ExtractFromTar: cannot remove old file: %w", err)
}
}
outFile, err := os.OpenFile(pathBuilder(header.Name), os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
outFile, err := os.OpenFile(entryPath, os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
if err != nil {
return fmt.Errorf("ExtractFromTar: OpenFile() failed: %w", err)
}
Expand All @@ -60,15 +77,19 @@
return fmt.Errorf("ExtractFromTar: outFile.Close() failed: %w", err)
}
case tar.TypeLink, tar.TypeSymlink:
if _, err := os.Lstat(pathBuilder(header.Name)); err == nil {
err = os.Remove(pathBuilder(header.Name))
if _, err := os.Lstat(entryPath); err == nil {
err = os.Remove(entryPath)
if err != nil {
return fmt.Errorf("ExtractFromTar: cannot remove old symlink: %w", err)
}
}
if err := os.Symlink(pathBuilder(header.Linkname), pathBuilder(header.Name)); err != nil {
linkPath, err := safePath(header.Linkname)

Check failure

Code scanning / CodeQL

Arbitrary file write extracting an archive containing symbolic links High

Unresolved path from an archive header, which may point outside the archive root, is used in
symlink creation
Loading
.
if err != nil {
return fmt.Errorf("ExtractFromTar: invalid link name %q: %w", header.Linkname, err)
}
if err := os.Symlink(linkPath, entryPath); err != nil {
return fmt.Errorf("ExtractFromTar: Symlink(%s, %s) failed: %w",
pathBuilder(header.Name), pathBuilder(header.Linkname), err)
entryPath, linkPath, err)
}
default:
return fmt.Errorf(
Expand Down
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