| 1 | package rootstate |
| 2 | |
| 3 | import ( |
| 4 | "os" |
| 5 | "path/filepath" |
| 6 | "strings" |
| 7 | |
| 8 | "github.com/carlosframework/platform/internal/safefile" |
| 9 | "golang.org/x/sys/unix" |
| 10 | ) |
| 11 | |
| 12 | func OpenAuthorityFile(path string) (*os.File, error) { |
| 13 | if !filepath.IsAbs(path) || filepath.Clean(path) != path || path == "/" { |
| 14 | return nil, os.ErrPermission |
| 15 | } |
| 16 | parent, err := os.Open("/") |
| 17 | if err != nil { |
| 18 | return nil, err |
| 19 | } |
| 20 | defer parent.Close() |
| 21 | return openAuthorityFile(parent, strings.Split(strings.TrimPrefix(path, "/"), "/"), 0) |
| 22 | } |
| 23 | |
| 24 | func openAuthorityFile(parent *os.File, parts []string, owner uint32) (*os.File, error) { |
| 25 | if len(parts) == 0 { |
| 26 | return nil, os.ErrPermission |
| 27 | } |
| 28 | fd, err := unix.FcntlInt(parent.Fd(), unix.F_DUPFD_CLOEXEC, 0) |
| 29 | if err != nil { |
| 30 | return nil, err |
| 31 | } |
| 32 | defer func() { unix.Close(fd) }() |
| 33 | if err := trusted(fd, owner, unix.S_IFDIR); err != nil { |
| 34 | return nil, err |
| 35 | } |
| 36 | for i, name := range parts { |
| 37 | if !component(name) { |
| 38 | return nil, os.ErrPermission |
| 39 | } |
| 40 | if i == len(parts)-1 { |
| 41 | break |
| 42 | } |
| 43 | next, err := unix.Openat(fd, name, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_NOFOLLOW|unix.O_CLOEXEC, 0) |
| 44 | if err != nil { |
| 45 | return nil, err |
| 46 | } |
| 47 | unix.Close(fd) |
| 48 | fd = next |
| 49 | if err := trusted(fd, owner, unix.S_IFDIR); err != nil { |
| 50 | return nil, err |
| 51 | } |
| 52 | } |
| 53 | f, err := safefile.OpenFileAt(fd, parts[len(parts)-1], os.O_RDONLY, 0) |
| 54 | if err != nil { |
| 55 | return nil, err |
| 56 | } |
| 57 | if err := trusted(int(f.Fd()), owner, unix.S_IFREG); err != nil { |
| 58 | f.Close() |
| 59 | return nil, err |
| 60 | } |
| 61 | return f, nil |
| 62 | } |
| 63 | |
amadan