| 1 | //go:build linux |
| 2 | |
| 3 | package host |
| 4 | |
| 5 | import ( |
| 6 | "bytes" |
| 7 | "errors" |
| 8 | "log" |
| 9 | "net" |
| 10 | "os" |
| 11 | "path/filepath" |
| 12 | "strings" |
| 13 | "testing" |
| 14 | |
| 15 | "golang.org/x/sys/unix" |
| 16 | ) |
| 17 | |
| 18 | func TestBootstrapRegistryPlantedLinks(t *testing.T) { |
| 19 | for _, dangling := range []bool{false, true} { |
| 20 | t.Run(map[bool]string{false: "existing", true: "dangling"}[dangling], func(t *testing.T) { |
| 21 | root := t.TempDir() |
| 22 | victim := filepath.Join(t.TempDir(), "victim") |
| 23 | if !dangling { |
| 24 | if err := os.WriteFile(victim, []byte("preserve"), 0o600); err != nil { |
| 25 | t.Fatal(err) |
| 26 | } |
| 27 | } |
| 28 | if err := os.Mkdir(filepath.Join(root, "data"), 0o750); err != nil { |
| 29 | t.Fatal(err) |
| 30 | } |
| 31 | if err := os.Symlink(victim, filepath.Join(root, "data", "registry.db")); err != nil { |
| 32 | t.Fatal(err) |
| 33 | } |
| 34 | if err := bootstrap(root, nil); err != nil { |
| 35 | t.Fatal(err) |
| 36 | } |
| 37 | got, err := os.ReadFile(victim) |
| 38 | if dangling { |
| 39 | if !errors.Is(err, os.ErrNotExist) { |
| 40 | t.Fatalf("dangling target created: %v", err) |
| 41 | } |
| 42 | } else if err != nil || string(got) != "preserve" { |
| 43 | t.Fatalf("victim changed: %q %v", got, err) |
| 44 | } |
| 45 | }) |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | func TestBootstrapRefusesWritableParentSymlink(t *testing.T) { |
| 50 | for _, parent := range []string{"data", "data/.instances", "run/carlos"} { |
| 51 | t.Run(strings.ReplaceAll(parent, "/", "_"), func(t *testing.T) { |
| 52 | root, victim := t.TempDir(), t.TempDir() |
| 53 | if err := os.Chmod(victim, 0o711); err != nil { |
| 54 | t.Fatal(err) |
| 55 | } |
| 56 | path := filepath.Join(root, parent) |
| 57 | if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil { |
| 58 | t.Fatal(err) |
| 59 | } |
| 60 | if err := os.Symlink(victim, path); err != nil { |
| 61 | t.Fatal(err) |
| 62 | } |
| 63 | if err := bootstrap(root, nil); err == nil { |
| 64 | t.Fatal("accepted parent symlink") |
| 65 | } |
| 66 | st, err := os.Stat(victim) |
| 67 | if err != nil || st.Mode().Perm() != 0o711 { |
| 68 | t.Fatalf("victim mode changed: %v %v", st, err) |
| 69 | } |
| 70 | entries, err := os.ReadDir(victim) |
| 71 | if err != nil || len(entries) != 0 { |
| 72 | t.Fatalf("victim populated: %v %v", entries, err) |
| 73 | } |
| 74 | }) |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | func TestBootstrapOwnershipWalkSkipsUnsafeEntries(t *testing.T) { |
| 79 | dir := t.TempDir() |
| 80 | victim := filepath.Join(t.TempDir(), "victim") |
| 81 | if err := os.WriteFile(victim, []byte("preserve"), 0o600); err != nil { |
| 82 | t.Fatal(err) |
| 83 | } |
| 84 | if err := os.Chmod(victim, 0o750|os.ModeSetuid|os.ModeSetgid); err != nil { |
| 85 | t.Fatal(err) |
| 86 | } |
| 87 | before, err := os.Stat(victim) |
| 88 | if err != nil { |
| 89 | t.Fatal(err) |
| 90 | } |
| 91 | for _, name := range []string{"registry.db-wal", "registry.db-shm"} { |
| 92 | if err := os.Link(victim, filepath.Join(dir, name)); err != nil { |
| 93 | t.Fatal(err) |
| 94 | } |
| 95 | } |
| 96 | if err := os.Symlink(victim, filepath.Join(dir, "registry.db")); err != nil { |
| 97 | t.Fatal(err) |
| 98 | } |
| 99 | if err := unix.Mkfifo(filepath.Join(dir, "fifo"), 0o600); err != nil { |
| 100 | t.Fatal(err) |
| 101 | } |
| 102 | socket, err := net.Listen("unix", filepath.Join(dir, "socket")) |
| 103 | if err != nil { |
| 104 | t.Fatal(err) |
| 105 | } |
| 106 | defer socket.Close() |
| 107 | if err := os.Mkdir(filepath.Join(dir, "nested"), 0o750); err != nil { |
| 108 | t.Fatal(err) |
| 109 | } |
| 110 | plain := filepath.Join(dir, "nested", "plain") |
| 111 | if err := os.WriteFile(plain, []byte("ordinary"), 0o640); err != nil { |
| 112 | t.Fatal(err) |
| 113 | } |
| 114 | var logs bytes.Buffer |
| 115 | old := log.Writer() |
| 116 | log.SetOutput(&logs) |
| 117 | defer log.SetOutput(old) |
| 118 | if err := bootstrapChownTree(dir, os.Getuid(), os.Getgid()); err != nil { |
| 119 | t.Fatal(err) |
| 120 | } |
| 121 | after, err := os.Stat(victim) |
| 122 | if err != nil { |
| 123 | t.Fatal(err) |
| 124 | } |
| 125 | if after.Mode() != before.Mode() { |
| 126 | t.Fatalf("hard-linked victim ownership operation cleared mode: %v -> %v", before.Mode(), after.Mode()) |
| 127 | } |
| 128 | got, err := os.ReadFile(victim) |
| 129 | if err != nil || string(got) != "preserve" { |
| 130 | t.Fatalf("victim changed: %q %v", got, err) |
| 131 | } |
| 132 | for _, name := range []string{"registry.db", "registry.db-wal", "registry.db-shm", "fifo", "socket"} { |
| 133 | if !strings.Contains(logs.String(), filepath.Join(dir, name)) { |
| 134 | t.Errorf("missing alert for %s: %s", name, logs.String()) |
| 135 | } |
| 136 | } |
| 137 | got, err = os.ReadFile(plain) |
| 138 | if err != nil || string(got) != "ordinary" { |
| 139 | t.Fatalf("plain file changed: %q %v", got, err) |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | func TestBootstrapOwnershipWalkDoesNotCrossBindMount(t *testing.T) { |
| 144 | if os.Geteuid() != 0 { |
| 145 | t.Skip("bind mount test requires root with CAP_SYS_ADMIN") |
| 146 | } |
| 147 | dir, source := t.TempDir(), t.TempDir() |
| 148 | target := filepath.Join(dir, "bind") |
| 149 | if err := os.Mkdir(target, 0o750); err != nil { |
| 150 | t.Fatal(err) |
| 151 | } |
| 152 | if err := os.Chmod(source, 0o750|os.ModeSetgid); err != nil { |
| 153 | t.Fatal(err) |
| 154 | } |
| 155 | if err := unix.Mount(source, target, "", unix.MS_BIND, ""); err != nil { |
| 156 | if errors.Is(err, unix.EPERM) || errors.Is(err, unix.EACCES) { |
| 157 | t.Skipf("bind mount test requires CAP_SYS_ADMIN: %v", err) |
| 158 | } |
| 159 | t.Fatal(err) |
| 160 | } |
| 161 | defer unix.Unmount(target, 0) |
| 162 | before, err := os.Stat(source) |
| 163 | if err != nil { |
| 164 | t.Fatal(err) |
| 165 | } |
| 166 | if err := bootstrapChownTree(dir, 65534, 65534); err != nil { |
| 167 | t.Fatal(err) |
| 168 | } |
| 169 | after, err := os.Stat(source) |
| 170 | if err != nil { |
| 171 | t.Fatal(err) |
| 172 | } |
| 173 | var sourceStat unix.Stat_t |
| 174 | if err := unix.Stat(source, &sourceStat); err != nil { |
| 175 | t.Fatal(err) |
| 176 | } |
| 177 | if before.Mode() != after.Mode() || sourceStat.Uid != uint32(os.Getuid()) { |
| 178 | t.Fatalf("crossed bind mount: mode %v -> %v, uid %d", before.Mode(), after.Mode(), sourceStat.Uid) |
| 179 | } |
| 180 | } |
| 181 | |
amadan