| 1 | package rootstate |
| 2 | |
| 3 | import ( |
| 4 | "io" |
| 5 | "os" |
| 6 | "path/filepath" |
| 7 | "testing" |
| 8 | |
| 9 | "golang.org/x/sys/unix" |
| 10 | ) |
| 11 | |
| 12 | func TestPlan14AuthorityFilePrivateAncestors(t *testing.T) { |
| 13 | for _, attack := range []string{"none", "public-leaf-parent", "writable-anchor", "writable-ancestor", "writable-leaf", "ancestor-link", "leaf-link", "hardlink", "fifo", "directory", "wrong-owner", "missing", "relative-component"} { |
| 14 | t.Run(attack, func(t *testing.T) { |
| 15 | root := t.TempDir() |
| 16 | if err := os.Chmod(root, 0700); err != nil { |
| 17 | t.Fatal(err) |
| 18 | } |
| 19 | path := filepath.Join(root, "private", "nested", "journal") |
| 20 | if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil { |
| 21 | t.Fatal(err) |
| 22 | } |
| 23 | if err := os.WriteFile(path, []byte("retained"), 0600); err != nil { |
| 24 | t.Fatal(err) |
| 25 | } |
| 26 | must := func(err error) { |
| 27 | t.Helper() |
| 28 | if err != nil { |
| 29 | t.Fatal(err) |
| 30 | } |
| 31 | } |
| 32 | owner := uint32(os.Geteuid()) |
| 33 | parts := []string{"private", "nested", "journal"} |
| 34 | switch attack { |
| 35 | case "public-leaf-parent": |
| 36 | must(os.Chmod(filepath.Dir(path), 0755)) |
| 37 | case "writable-anchor": |
| 38 | must(os.Chmod(root, 0777)) |
| 39 | case "writable-ancestor": |
| 40 | must(os.Chmod(filepath.Join(root, "private"), 0777)) |
| 41 | case "writable-leaf": |
| 42 | must(os.Chmod(path, 0666)) |
| 43 | case "ancestor-link": |
| 44 | must(os.Rename(filepath.Join(root, "private"), filepath.Join(root, "saved"))) |
| 45 | must(os.Symlink("saved", filepath.Join(root, "private"))) |
| 46 | case "leaf-link": |
| 47 | must(os.Rename(path, path+".saved")) |
| 48 | must(os.Symlink("journal.saved", path)) |
| 49 | case "hardlink": |
| 50 | must(os.Link(path, path+".alias")) |
| 51 | case "fifo": |
| 52 | must(os.Remove(path)) |
| 53 | must(unix.Mkfifo(path, 0600)) |
| 54 | case "directory": |
| 55 | must(os.Remove(path)) |
| 56 | must(os.Mkdir(path, 0700)) |
| 57 | case "wrong-owner": |
| 58 | owner++ |
| 59 | case "missing": |
| 60 | must(os.Remove(path)) |
| 61 | case "relative-component": |
| 62 | parts = []string{"private", "nested", "..", "nested", "journal"} |
| 63 | } |
| 64 | parent, err := os.Open(root) |
| 65 | must(err) |
| 66 | defer parent.Close() |
| 67 | f, err := openAuthorityFile(parent, parts, owner) |
| 68 | if attack != "none" && attack != "public-leaf-parent" { |
| 69 | if err == nil { |
| 70 | f.Close() |
| 71 | t.Fatal("hostile authority file accepted") |
| 72 | } |
| 73 | return |
| 74 | } |
| 75 | if err != nil { |
| 76 | t.Fatalf("private authority file refused: %v", err) |
| 77 | } |
| 78 | defer f.Close() |
| 79 | raw, err := io.ReadAll(f) |
| 80 | if err != nil || string(raw) != "retained" { |
| 81 | t.Fatalf("retained bytes: %q %v", raw, err) |
| 82 | } |
| 83 | }) |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | func TestPlan14AuthorityFileAbsoluteBoundary(t *testing.T) { |
| 88 | for _, path := range []string{"relative", "/etc/../etc/passwd", "/", filepath.Join(t.TempDir(), "missing")} { |
| 89 | if f, err := OpenAuthorityFile(path); err == nil { |
| 90 | f.Close() |
| 91 | t.Fatalf("untrusted path accepted: %q", path) |
| 92 | } |
| 93 | } |
| 94 | t.Run("public-root-owned-file", func(t *testing.T) { |
| 95 | for _, path := range []string{"/", "/usr", "/usr/bin", "/usr/bin/true"} { |
| 96 | var st unix.Stat_t |
| 97 | if err := unix.Lstat(path, &st); err != nil { |
| 98 | t.Fatal(err) |
| 99 | } |
| 100 | if st.Uid != 0 { |
| 101 | t.Skipf("root-owned fixture unavailable: %s uid=%d", path, st.Uid) |
| 102 | } |
| 103 | } |
| 104 | f, err := OpenAuthorityFile("/usr/bin/true") |
| 105 | if err != nil { |
| 106 | t.Fatal(err) |
| 107 | } |
| 108 | f.Close() |
| 109 | }) |
| 110 | } |
| 111 | |
amadan