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| 1 | package rootstate |
| 2 | |
| 3 | import ( |
| 4 | "os" |
| 5 | "path/filepath" |
| 6 | |
| 7 | "golang.org/x/sys/unix" |
| 8 | ) |
| 9 | |
| 10 | func EnsurePublicDir(path string) error { |
| 11 | if !filepath.IsAbs(path) || filepath.Clean(path) != path || os.Geteuid() != 0 { |
| 12 | return os.ErrPermission |
| 13 | } |
| 14 | parent, err := Open(filepath.Dir(path), true, true) |
| 15 | if err != nil { |
| 16 | return err |
| 17 | } |
| 18 | defer parent.Close() |
| 19 | return ensurePublicChild(parent.(*directory), filepath.Base(path)) |
| 20 | } |
| 21 | |
| 22 | func ensurePublicChild(parent *directory, name string) error { |
| 23 | if !component(name) || parent.check() != nil { |
| 24 | return os.ErrPermission |
| 25 | } |
| 26 | fd := int(parent.file.Fd()) |
| 27 | if err := unix.Mkdirat(fd, name, 0755); err != nil && err != unix.EEXIST { |
| 28 | return err |
| 29 | } |
| 30 | child, err := unix.Openat(fd, name, unix.O_RDONLY|unix.O_DIRECTORY|unix.O_NOFOLLOW|unix.O_CLOEXEC, 0) |
| 31 | if err != nil { |
| 32 | return err |
| 33 | } |
| 34 | defer unix.Close(child) |
| 35 | if err := trusted(child, parent.owner, unix.S_IFDIR); err != nil { |
| 36 | return err |
| 37 | } |
| 38 | var st unix.Stat_t |
| 39 | if err := unix.Fstat(child, &st); err != nil { |
| 40 | return err |
| 41 | } |
| 42 | if st.Gid != 0 || st.Mode&07777 != 0700 && st.Mode&07777 != 0755 { |
| 43 | return os.ErrPermission |
| 44 | } |
| 45 | if st.Mode&07777 == 0700 { |
| 46 | if err := unix.Fchmod(child, 0755); err != nil { |
| 47 | return err |
| 48 | } |
| 49 | } |
| 50 | if err := unix.Fsync(child); err != nil { |
| 51 | return err |
| 52 | } |
| 53 | return unix.Fsync(fd) |
| 54 | } |
| 55 | |
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