package system // import "github.com/docker/docker/pkg/system" import ( "os" "path/filepath" "regexp" "strconv" "strings" "sync" "syscall" "time" "unsafe" "golang.org/x/sys/windows" ) const ( // SddlAdministratorsLocalSystem is local administrators plus NT AUTHORITY\System SddlAdministratorsLocalSystem = "D:P(A;OICI;GA;;;BA)(A;OICI;GA;;;SY)" ) // MkdirAllWithACL is a wrapper for MkdirAll that creates a directory // with an appropriate SDDL defined ACL. func MkdirAllWithACL(path string, perm os.FileMode, sddl string) error { return mkdirall(path, true, sddl) } // MkdirAll implementation that is volume path aware for Windows. It can be used // as a drop-in replacement for os.MkdirAll() func MkdirAll(path string, _ os.FileMode) error { return mkdirall(path, false, "") } // mkdirall is a custom version of os.MkdirAll modified for use on Windows // so that it is both volume path aware, and can create a directory with // a DACL. func mkdirall(path string, applyACL bool, sddl string) error { if re := regexp.MustCompile(`^\\\\\?\\Volume{[a-z0-9-]+}$`); re.MatchString(path) { return nil } // The rest of this method is largely copied from os.MkdirAll and should be kept // as-is to ensure compatibility. // Fast path: if we can tell whether path is a directory or file, stop with success or error. dir, err := os.Stat(path) if err == nil { if dir.IsDir() { return nil } return &os.PathError{ Op: "mkdir", Path: path, Err: syscall.ENOTDIR, } } // Slow path: make sure parent exists and then call Mkdir for path. i := len(path) for i > 0 && os.IsPathSeparator(path[i-1]) { // Skip trailing path separator. i-- } j := i for j > 0 && !os.IsPathSeparator(path[j-1]) { // Scan backward over element. j-- } if j > 1 { // Create parent err = mkdirall(path[0:j-1], false, sddl) if err != nil { return err } } // Parent now exists; invoke os.Mkdir or mkdirWithACL and use its result. if applyACL { err = mkdirWithACL(path, sddl) } else { err = os.Mkdir(path, 0) } if err != nil { // Handle arguments like "foo/." by // double-checking that directory doesn't exist. dir, err1 := os.Lstat(path) if err1 == nil && dir.IsDir() { return nil } return err } return nil } // mkdirWithACL creates a new directory. If there is an error, it will be of // type *PathError. . // // This is a modified and combined version of os.Mkdir and windows.Mkdir // in golang to cater for creating a directory am ACL permitting full // access, with inheritance, to any subfolder/file for Built-in Administrators // and Local System. func mkdirWithACL(name string, sddl string) error { sa := windows.SecurityAttributes{Length: 0} sd, err := windows.SecurityDescriptorFromString(sddl) if err != nil { return &os.PathError{Op: "mkdir", Path: name, Err: err} } sa.Length = uint32(unsafe.Sizeof(sa)) sa.InheritHandle = 1 sa.SecurityDescriptor = sd namep, err := windows.UTF16PtrFromString(name) if err != nil { return &os.PathError{Op: "mkdir", Path: name, Err: err} } e := windows.CreateDirectory(namep, &sa) if e != nil { return &os.PathError{Op: "mkdir", Path: name, Err: e} } return nil } // IsAbs is a platform-specific wrapper for filepath.IsAbs. On Windows, // golang filepath.IsAbs does not consider a path \windows\system32 as absolute // as it doesn't start with a drive-letter/colon combination. However, in // docker we need to verify things such as WORKDIR /windows/system32 in // a Dockerfile (which gets translated to \windows\system32 when being processed // by the daemon. This SHOULD be treated as absolute from a docker processing // perspective. func IsAbs(path string) bool { if filepath.IsAbs(path) || strings.HasPrefix(path, string(os.PathSeparator)) { return true } return false } // The origin of the functions below here are the golang OS and windows packages, // slightly modified to only cope with files, not directories due to the // specific use case. // // The alteration is to allow a file on Windows to be opened with // FILE_FLAG_SEQUENTIAL_SCAN (particular for docker load), to avoid eating // the standby list, particularly when accessing large files such as layer.tar. // CreateSequential creates the named file with mode 0666 (before umask), truncating // it if it already exists. If successful, methods on the returned // File can be used for I/O; the associated file descriptor has mode // O_RDWR. // If there is an error, it will be of type *PathError. func CreateSequential(name string) (*os.File, error) { return OpenFileSequential(name, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0) } // OpenSequential opens the named file for reading. If successful, methods on // the returned file can be used for reading; the associated file // descriptor has mode O_RDONLY. // If there is an error, it will be of type *PathError. func OpenSequential(name string) (*os.File, error) { return OpenFileSequential(name, os.O_RDONLY, 0) } // OpenFileSequential is the generalized open call; most users will use Open // or Create instead. // If there is an error, it will be of type *PathError. func OpenFileSequential(name string, flag int, _ os.FileMode) (*os.File, error) { if name == "" { return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOENT} } r, errf := windowsOpenFileSequential(name, flag, 0) if errf == nil { return r, nil } return nil, &os.PathError{Op: "open", Path: name, Err: errf} } func windowsOpenFileSequential(name string, flag int, _ os.FileMode) (file *os.File, err error) { r, e := windowsOpenSequential(name, flag|windows.O_CLOEXEC, 0) if e != nil { return nil, e } return os.NewFile(uintptr(r), name), nil } func makeInheritSa() *windows.SecurityAttributes { var sa windows.SecurityAttributes sa.Length = uint32(unsafe.Sizeof(sa)) sa.InheritHandle = 1 return &sa } func windowsOpenSequential(path string, mode int, _ uint32) (fd windows.Handle, err error) { if len(path) == 0 { return windows.InvalidHandle, windows.ERROR_FILE_NOT_FOUND } pathp, err := windows.UTF16PtrFromString(path) if err != nil { return windows.InvalidHandle, err } var access uint32 switch mode & (windows.O_RDONLY | windows.O_WRONLY | windows.O_RDWR) { case windows.O_RDONLY: access = windows.GENERIC_READ case windows.O_WRONLY: access = windows.GENERIC_WRITE case windows.O_RDWR: access = windows.GENERIC_READ | windows.GENERIC_WRITE } if mode&windows.O_CREAT != 0 { access |= windows.GENERIC_WRITE } if mode&windows.O_APPEND != 0 { access &^= windows.GENERIC_WRITE access |= windows.FILE_APPEND_DATA } sharemode := uint32(windows.FILE_SHARE_READ | windows.FILE_SHARE_WRITE) var sa *windows.SecurityAttributes if mode&windows.O_CLOEXEC == 0 { sa = makeInheritSa() } var createmode uint32 switch { case mode&(windows.O_CREAT|windows.O_EXCL) == (windows.O_CREAT | windows.O_EXCL): createmode = windows.CREATE_NEW case mode&(windows.O_CREAT|windows.O_TRUNC) == (windows.O_CREAT | windows.O_TRUNC): createmode = windows.CREATE_ALWAYS case mode&windows.O_CREAT == windows.O_CREAT: createmode = windows.OPEN_ALWAYS case mode&windows.O_TRUNC == windows.O_TRUNC: createmode = windows.TRUNCATE_EXISTING default: createmode = windows.OPEN_EXISTING } // Use FILE_FLAG_SEQUENTIAL_SCAN rather than FILE_ATTRIBUTE_NORMAL as implemented in golang. // https://msdn.microsoft.com/en-us/library/windows/desktop/aa363858(v=vs.85).aspx const fileFlagSequentialScan = 0x08000000 // FILE_FLAG_SEQUENTIAL_SCAN h, e := windows.CreateFile(pathp, access, sharemode, sa, createmode, fileFlagSequentialScan, 0) return h, e } // Helpers for TempFileSequential var rand uint32 var randmu sync.Mutex func reseed() uint32 { return uint32(time.Now().UnixNano() + int64(os.Getpid())) } func nextSuffix() string { randmu.Lock() r := rand if r == 0 { r = reseed() } r = r*1664525 + 1013904223 // constants from Numerical Recipes rand = r randmu.Unlock() return strconv.Itoa(int(1e9 + r%1e9))[1:] } // TempFileSequential is a copy of os.CreateTemp, modified to use sequential // file access. Below is the original comment from golang: // TempFile creates a new temporary file in the directory dir // with a name beginning with prefix, opens the file for reading // and writing, and returns the resulting *os.File. // If dir is the empty string, TempFile uses the default directory // for temporary files (see os.TempDir). // Multiple programs calling TempFile simultaneously // will not choose the same file. The caller can use f.Name() // to find the pathname of the file. It is the caller's responsibility // to remove the file when no longer needed. func TempFileSequential(dir, prefix string) (f *os.File, err error) { if dir == "" { dir = os.TempDir() } nconflict := 0 for i := 0; i < 10000; i++ { name := filepath.Join(dir, prefix+nextSuffix()) f, err = OpenFileSequential(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600) if os.IsExist(err) { if nconflict++; nconflict > 10 { randmu.Lock() rand = reseed() randmu.Unlock() } continue } break } return }