| 1 | //go:build linux |
| 2 | |
| 3 | package hostfiles |
| 4 | |
| 5 | import ( |
| 6 | "crypto/sha256" |
| 7 | "encoding/hex" |
| 8 | "errors" |
| 9 | "os" |
| 10 | "path/filepath" |
| 11 | "syscall" |
| 12 | "testing" |
| 13 | "time" |
| 14 | |
| 15 | "github.com/carlosframework/platform/internal/instancefs" |
| 16 | ) |
| 17 | |
| 18 | // presentBounded runs Present and fails the test if it does not return: a |
| 19 | // read that opened a planted FIFO without O_NONBLOCK would block for ever. |
| 20 | func presentBounded(t *testing.T, dir, envPath string, m Manifest, envAbsent bool) (bool, error) { |
| 21 | t.Helper() |
| 22 | type res struct { |
| 23 | ok bool |
| 24 | err error |
| 25 | } |
| 26 | done := make(chan res, 1) |
| 27 | go func() { ok, err := Present(dir, envPath, m, envAbsent); done <- res{ok, err} }() |
| 28 | select { |
| 29 | case r := <-done: |
| 30 | return r.ok, r.err |
| 31 | case <-time.After(20 * time.Second): |
| 32 | t.Fatal("Present did not return: it blocked on what the tenant planted") |
| 33 | return false, nil |
| 34 | } |
| 35 | } |
| 36 | |
| 37 | func presentEntry(body []byte) Entry { |
| 38 | sum := sha256.Sum256(body) |
| 39 | return Entry{Object: "o", SHA256: hex.EncodeToString(sum[:]), Size: int64(len(body)), Seq: 1} |
| 40 | } |
| 41 | |
| 42 | // Present reads the files directory and the env file, both in the |
| 43 | // tenant's instance directory, through main's safe open (instancefs): a |
| 44 | // symlink at a name or beneath the root, a FIFO, or a file larger than |
| 45 | // its entry is not present and is never read through or waited on; a |
| 46 | // symlink at the root itself, or in the path to it, is an error. |
| 47 | func TestPresentReadsTenantGroundThroughTheSafeOpen(t *testing.T) { |
| 48 | body := []byte("delta") |
| 49 | env := []byte("CARLOS_ADMIN_TOKEN=t\n") |
| 50 | m := Manifest{V: ManifestVersion, Entries: map[string]Entry{"b/c/d.bin": presentEntry(body)}, Platform: map[string]Entry{EnvItem: presentEntry(env)}} |
| 51 | // setup lays out a good install: inst/files/b/c/d.bin and inst/shop.example.env. |
| 52 | setup := func(t *testing.T) (files, envPath string) { |
| 53 | t.Helper() |
| 54 | inst := filepath.Join(t.TempDir(), "inst") |
| 55 | files = filepath.Join(inst, "files") |
| 56 | if err := os.MkdirAll(filepath.Join(files, "b", "c"), 0o700); err != nil { |
| 57 | t.Fatal(err) |
| 58 | } |
| 59 | if err := os.WriteFile(filepath.Join(files, "b", "c", "d.bin"), body, 0o600); err != nil { |
| 60 | t.Fatal(err) |
| 61 | } |
| 62 | envPath = filepath.Join(inst, "shop.example.env") |
| 63 | if err := os.WriteFile(envPath, env, 0o600); err != nil { |
| 64 | t.Fatal(err) |
| 65 | } |
| 66 | if ok, err := Present(files, envPath, m, false); err != nil || !ok { |
| 67 | t.Fatalf("a good install: %v %v", ok, err) |
| 68 | } |
| 69 | return files, envPath |
| 70 | } |
| 71 | // linkTo replaces path with a symlink to a copy of the same bytes or |
| 72 | // directory elsewhere, so a read that followed it would be satisfied. |
| 73 | linkTo := func(t *testing.T, path string) { |
| 74 | t.Helper() |
| 75 | moved := filepath.Join(t.TempDir(), "moved") |
| 76 | if err := os.Rename(path, moved); err != nil { |
| 77 | t.Fatal(err) |
| 78 | } |
| 79 | if err := os.Symlink(moved, path); err != nil { |
| 80 | t.Fatal(err) |
| 81 | } |
| 82 | } |
| 83 | fifo := func(t *testing.T, path string) { |
| 84 | t.Helper() |
| 85 | if err := os.Remove(path); err != nil { |
| 86 | t.Fatal(err) |
| 87 | } |
| 88 | if err := syscall.Mkfifo(path, 0o600); err != nil { |
| 89 | t.Fatal(err) |
| 90 | } |
| 91 | } |
| 92 | grow := func(t *testing.T, path string, keep []byte) { |
| 93 | t.Helper() |
| 94 | if err := os.WriteFile(path, append(append([]byte(nil), keep...), "more"...), 0o600); err != nil { |
| 95 | t.Fatal(err) |
| 96 | } |
| 97 | } |
| 98 | for _, tc := range []struct { |
| 99 | name string |
| 100 | plant func(t *testing.T, files, envPath string) |
| 101 | wantErr error // nil: not present, no error |
| 102 | }{ |
| 103 | {"a symlink at a file", func(t *testing.T, files, _ string) { linkTo(t, filepath.Join(files, "b", "c", "d.bin")) }, nil}, |
| 104 | {"a symlinked directory beneath the root", func(t *testing.T, files, _ string) { linkTo(t, filepath.Join(files, "b")) }, nil}, |
| 105 | {"a FIFO at a file", func(t *testing.T, files, _ string) { fifo(t, filepath.Join(files, "b", "c", "d.bin")) }, nil}, |
| 106 | {"a file larger than its entry", func(t *testing.T, files, _ string) { grow(t, filepath.Join(files, "b", "c", "d.bin"), body) }, nil}, |
| 107 | {"a symlink at the files root", func(t *testing.T, files, _ string) { linkTo(t, files) }, instancefs.ErrSymlink}, |
| 108 | {"a symlink at the env file", func(t *testing.T, _, envPath string) { linkTo(t, envPath) }, nil}, |
| 109 | {"a FIFO at the env file", func(t *testing.T, _, envPath string) { fifo(t, envPath) }, nil}, |
| 110 | {"an env file larger than its entry", func(t *testing.T, _, envPath string) { grow(t, envPath, env) }, nil}, |
| 111 | {"a symlinked instance directory", func(t *testing.T, _, envPath string) { linkTo(t, filepath.Dir(envPath)) }, instancefs.ErrSymlink}, |
| 112 | } { |
| 113 | t.Run(tc.name, func(t *testing.T) { |
| 114 | files, envPath := setup(t) |
| 115 | tc.plant(t, files, envPath) |
| 116 | ok, err := presentBounded(t, files, envPath, m, false) |
| 117 | if ok || !errors.Is(err, tc.wantErr) || (tc.wantErr == nil && err != nil) { |
| 118 | t.Fatalf("Present = %v, %v; want false, %v", ok, err, tc.wantErr) |
| 119 | } |
| 120 | }) |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | // With the caller's evidence of no env file, an env file is "none" only |
| 125 | // when its directory opened with no symlink anywhere and the name is not |
| 126 | // in it: a FIFO or a link there is something, not none, and is never |
| 127 | // opened blocking; a linked directory is an error; a missing one is not |
| 128 | // evidence. |
| 129 | func TestPresentReadsNoEnvFileOnlyFromADirectoryThatOpened(t *testing.T) { |
| 130 | none := Manifest{V: ManifestVersion, Entries: map[string]Entry{}, Platform: map[string]Entry{}} |
| 131 | for _, tc := range []struct { |
| 132 | name string |
| 133 | plant func(t *testing.T, envPath string) |
| 134 | want bool |
| 135 | wantErr error |
| 136 | }{ |
| 137 | {"none there", func(*testing.T, string) {}, true, nil}, |
| 138 | {"a FIFO", func(t *testing.T, envPath string) { |
| 139 | if err := syscall.Mkfifo(envPath, 0o600); err != nil { |
| 140 | t.Fatal(err) |
| 141 | } |
| 142 | }, false, nil}, |
| 143 | {"a symlink to nothing", func(t *testing.T, envPath string) { |
| 144 | if err := os.Symlink(filepath.Join(t.TempDir(), "nothing"), envPath); err != nil { |
| 145 | t.Fatal(err) |
| 146 | } |
| 147 | }, false, nil}, |
| 148 | {"a symlinked directory", func(t *testing.T, envPath string) { |
| 149 | dir := filepath.Dir(envPath) |
| 150 | moved := filepath.Join(t.TempDir(), "moved") |
| 151 | if err := os.Rename(dir, moved); err != nil { |
| 152 | t.Fatal(err) |
| 153 | } |
| 154 | if err := os.Symlink(moved, dir); err != nil { |
| 155 | t.Fatal(err) |
| 156 | } |
| 157 | }, false, instancefs.ErrSymlink}, |
| 158 | {"a missing directory", func(t *testing.T, envPath string) { |
| 159 | if err := os.Remove(filepath.Dir(envPath)); err != nil { |
| 160 | t.Fatal(err) |
| 161 | } |
| 162 | }, false, nil}, |
| 163 | } { |
| 164 | t.Run(tc.name, func(t *testing.T) { |
| 165 | dir := filepath.Join(t.TempDir(), "inst") |
| 166 | if err := os.Mkdir(dir, 0o700); err != nil { |
| 167 | t.Fatal(err) |
| 168 | } |
| 169 | envPath := filepath.Join(dir, "shop.example.env") |
| 170 | tc.plant(t, envPath) |
| 171 | ok, err := presentBounded(t, t.TempDir(), envPath, none, true) |
| 172 | if ok != tc.want || !errors.Is(err, tc.wantErr) || (tc.wantErr == nil && err != nil) { |
| 173 | t.Fatalf("Present = %v, %v; want %v, %v", ok, err, tc.want, tc.wantErr) |
| 174 | } |
| 175 | }) |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | // A file far larger than its entry is answered from its size, never read |
| 180 | // whole: a tenant's sparse terabyte costs nothing to make. |
| 181 | func TestPresentNeverReadsPastAnEntrysSize(t *testing.T) { |
| 182 | body := []byte("delta") |
| 183 | m := Manifest{V: ManifestVersion, Entries: map[string]Entry{"big": presentEntry(body)}, Platform: map[string]Entry{}} |
| 184 | dir := t.TempDir() |
| 185 | f, err := os.Create(filepath.Join(dir, "big")) |
| 186 | if err != nil { |
| 187 | t.Fatal(err) |
| 188 | } |
| 189 | if _, err := f.Write(body); err != nil { |
| 190 | t.Fatal(err) |
| 191 | } |
| 192 | if err := f.Truncate(1 << 40); err != nil { |
| 193 | f.Close() |
| 194 | t.Skipf("no sparse terabyte here: %v", err) |
| 195 | } |
| 196 | f.Close() |
| 197 | if ok, err := presentBounded(t, dir, filepath.Join(t.TempDir(), "shop.example.env"), m, true); ok || err != nil { |
| 198 | t.Fatalf("Present = %v, %v; want false", ok, err) |
| 199 | } |
| 200 | } |
| 201 | |
| 202 | // An empty entry's size and digest are what a FIFO with no writer reads |
| 203 | // as (zero bytes, then EOF), so only the regular-file check tells the two |
| 204 | // apart: a FIFO at an empty file's name is not present. |
| 205 | func TestPresentNeverTakesAFIFOForAnEmptyFile(t *testing.T) { |
| 206 | m := Manifest{V: ManifestVersion, Entries: map[string]Entry{"empty": presentEntry(nil)}, Platform: map[string]Entry{}} |
| 207 | dir := t.TempDir() |
| 208 | if err := os.WriteFile(filepath.Join(dir, "empty"), nil, 0o600); err != nil { |
| 209 | t.Fatal(err) |
| 210 | } |
| 211 | env := filepath.Join(t.TempDir(), "shop.example.env") |
| 212 | if ok, err := Present(dir, env, m, true); err != nil || !ok { |
| 213 | t.Fatalf("an empty file: %v %v", ok, err) |
| 214 | } |
| 215 | if err := os.Remove(filepath.Join(dir, "empty")); err != nil { |
| 216 | t.Fatal(err) |
| 217 | } |
| 218 | if err := syscall.Mkfifo(filepath.Join(dir, "empty"), 0o600); err != nil { |
| 219 | t.Fatal(err) |
| 220 | } |
| 221 | if ok, err := presentBounded(t, dir, env, m, true); ok || err != nil { |
| 222 | t.Fatalf("a FIFO at an empty file's name: %v, %v; want false", ok, err) |
| 223 | } |
| 224 | } |
| 225 | |
amadan