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@@ -0,0 +1,167 @@
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+package utils
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+
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+import (
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+ "encoding/binary"
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+ "encoding/json"
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+ "fmt"
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+ "io"
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+ "os"
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+ "path/filepath"
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+ "strconv"
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+ "strings"
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+ "unsafe"
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+
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+ securejoin "github.com/cyphar/filepath-securejoin"
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+ "golang.org/x/sys/unix"
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+)
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+
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+const (
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+ exitSignalOffset = 128
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+)
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+
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+// NativeEndian is the native byte order of the host system.
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+var NativeEndian binary.ByteOrder
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+
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+func init() {
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+ // Copied from <golang.org/x/net/internal/socket/sys.go>.
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+ i := uint32(1)
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+ b := (*[4]byte)(unsafe.Pointer(&i))
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+ if b[0] == 1 {
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+ NativeEndian = binary.LittleEndian
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+ } else {
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+ NativeEndian = binary.BigEndian
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+ }
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+}
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+
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+// ExitStatus returns the correct exit status for a process based on if it
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+// was signaled or exited cleanly
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+func ExitStatus(status unix.WaitStatus) int {
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+ if status.Signaled() {
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+ return exitSignalOffset + int(status.Signal())
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+ }
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+ return status.ExitStatus()
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+}
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+
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+// WriteJSON writes the provided struct v to w using standard json marshaling
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+func WriteJSON(w io.Writer, v interface{}) error {
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+ data, err := json.Marshal(v)
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+ if err != nil {
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+ return err
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+ }
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+ _, err = w.Write(data)
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+ return err
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+}
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+
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+// CleanPath makes a path safe for use with filepath.Join. This is done by not
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+// only cleaning the path, but also (if the path is relative) adding a leading
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+// '/' and cleaning it (then removing the leading '/'). This ensures that a
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+// path resulting from prepending another path will always resolve to lexically
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+// be a subdirectory of the prefixed path. This is all done lexically, so paths
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+// that include symlinks won't be safe as a result of using CleanPath.
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+func CleanPath(path string) string {
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+ // Deal with empty strings nicely.
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+ if path == "" {
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+ return ""
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+ }
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+
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+ // Ensure that all paths are cleaned (especially problematic ones like
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+ // "/../../../../../" which can cause lots of issues).
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+ path = filepath.Clean(path)
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+
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+ // If the path isn't absolute, we need to do more processing to fix paths
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+ // such as "../../../../<etc>/some/path". We also shouldn't convert absolute
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+ // paths to relative ones.
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+ if !filepath.IsAbs(path) {
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+ path = filepath.Clean(string(os.PathSeparator) + path)
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+ // This can't fail, as (by definition) all paths are relative to root.
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+ path, _ = filepath.Rel(string(os.PathSeparator), path)
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+ }
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+
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+ // Clean the path again for good measure.
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+ return filepath.Clean(path)
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+}
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+
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+// stripRoot returns the passed path, stripping the root path if it was
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+// (lexicially) inside it. Note that both passed paths will always be treated
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+// as absolute, and the returned path will also always be absolute. In
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+// addition, the paths are cleaned before stripping the root.
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+func stripRoot(root, path string) string {
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+ // Make the paths clean and absolute.
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+ root, path = CleanPath("/"+root), CleanPath("/"+path)
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+ switch {
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+ case path == root:
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+ path = "/"
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+ case root == "/":
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+ // do nothing
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+ case strings.HasPrefix(path, root+"/"):
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+ path = strings.TrimPrefix(path, root+"/")
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+ }
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+ return CleanPath("/" + path)
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+}
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+
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+// WithProcfd runs the passed closure with a procfd path (/proc/self/fd/...)
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+// corresponding to the unsafePath resolved within the root. Before passing the
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+// fd, this path is verified to have been inside the root -- so operating on it
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+// through the passed fdpath should be safe. Do not access this path through
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+// the original path strings, and do not attempt to use the pathname outside of
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+// the passed closure (the file handle will be freed once the closure returns).
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+func WithProcfd(root, unsafePath string, fn func(procfd string) error) error {
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+ // Remove the root then forcefully resolve inside the root.
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+ unsafePath = stripRoot(root, unsafePath)
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+ path, err := securejoin.SecureJoin(root, unsafePath)
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+ if err != nil {
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+ return fmt.Errorf("resolving path inside rootfs failed: %w", err)
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+ }
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+
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+ // Open the target path.
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+ fh, err := os.OpenFile(path, unix.O_PATH|unix.O_CLOEXEC, 0)
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+ if err != nil {
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+ return fmt.Errorf("open o_path procfd: %w", err)
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+ }
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+ defer fh.Close()
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+
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+ // Double-check the path is the one we expected.
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+ procfd := "/proc/self/fd/" + strconv.Itoa(int(fh.Fd()))
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+ if realpath, err := os.Readlink(procfd); err != nil {
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+ return fmt.Errorf("procfd verification failed: %w", err)
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+ } else if realpath != path {
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+ return fmt.Errorf("possibly malicious path detected -- refusing to operate on %s", realpath)
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+ }
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+
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+ // Run the closure.
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+ return fn(procfd)
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+}
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+
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+// SearchLabels searches a list of key-value pairs for the provided key and
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+// returns the corresponding value. The pairs must be separated with '='.
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+func SearchLabels(labels []string, query string) string {
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+ for _, l := range labels {
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+ parts := strings.SplitN(l, "=", 2)
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+ if len(parts) < 2 {
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+ continue
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+ }
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+ if parts[0] == query {
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+ return parts[1]
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+ }
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+ }
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+ return ""
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+}
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+
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+// Annotations returns the bundle path and user defined annotations from the
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+// libcontainer state. We need to remove the bundle because that is a label
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+// added by libcontainer.
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+func Annotations(labels []string) (bundle string, userAnnotations map[string]string) {
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+ userAnnotations = make(map[string]string)
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+ for _, l := range labels {
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+ parts := strings.SplitN(l, "=", 2)
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+ if len(parts) < 2 {
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+ continue
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+ }
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+ if parts[0] == "bundle" {
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+ bundle = parts[1]
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+ } else {
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+ userAnnotations[parts[0]] = parts[1]
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+ }
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+ }
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+ return
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+}
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