| 1 | //go:build linux |
| 2 | |
| 3 | package host |
| 4 | |
| 5 | import ( |
| 6 | "errors" |
| 7 | "os" |
| 8 | "path/filepath" |
| 9 | "syscall" |
| 10 | "testing" |
| 11 | |
| 12 | "github.com/carlosframework/platform/internal/instancefs" |
| 13 | ) |
| 14 | |
| 15 | // repeatInstall is a crash before the install's journal: the next install |
| 16 | // runs every write again over what the first left in the instance |
| 17 | // directory, which the app may have run in since. |
| 18 | func repeatInstall(t *testing.T, f *installFixture) { |
| 19 | t.Helper() |
| 20 | if _, err := f.install(); err != nil { |
| 21 | t.Fatal(err) |
| 22 | } |
| 23 | journal, _ := relocationInstallPath(f.r.DataDir, "rel-1") |
| 24 | if err := os.Remove(journal); err != nil { |
| 25 | t.Fatal(err) |
| 26 | } |
| 27 | } |
| 28 | |
| 29 | // decoy is a directory the tenant must never get written or removed into: |
| 30 | // the box's own data, say. It holds one file the tests check survives. |
| 31 | func decoy(t *testing.T) string { |
| 32 | t.Helper() |
| 33 | d := t.TempDir() |
| 34 | if err := os.WriteFile(filepath.Join(d, buildHost+".env"), []byte("NOT=the tenant's\n"), 0o600); err != nil { |
| 35 | t.Fatal(err) |
| 36 | } |
| 37 | return d |
| 38 | } |
| 39 | |
| 40 | // untouched fails unless d holds exactly the decoy's own file, unchanged. |
| 41 | func untouched(t *testing.T, d string) { |
| 42 | t.Helper() |
| 43 | names, err := os.ReadDir(d) |
| 44 | if err != nil { |
| 45 | t.Fatal(err) |
| 46 | } |
| 47 | if len(names) != 1 || names[0].Name() != buildHost+".env" { |
| 48 | t.Fatalf("the install wrote into a directory outside the tenant's: %v", names) |
| 49 | } |
| 50 | if b, err := os.ReadFile(filepath.Join(d, buildHost+".env")); err != nil || string(b) != "NOT=the tenant's\n" { |
| 51 | t.Fatalf("the decoy's file was changed: %q %v", b, err) |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | // relink moves path aside and puts a symlink to target in its place. |
| 56 | func relink(t *testing.T, path, target string) string { |
| 57 | t.Helper() |
| 58 | moved := path + ".moved" |
| 59 | if err := os.Rename(path, moved); err != nil { |
| 60 | t.Fatal(err) |
| 61 | } |
| 62 | if err := os.Symlink(target, path); err != nil { |
| 63 | t.Fatal(err) |
| 64 | } |
| 65 | return moved |
| 66 | } |
| 67 | |
| 68 | // A repeated install makes, restores and writes nothing through what the |
| 69 | // tenant left in its instance directory: a symlink at <instance>/<host> |
| 70 | // or at the instance directory itself, or a FIFO at <instance>/<host>, |
| 71 | // refuses the install, never blocks it, and nothing lands outside. |
| 72 | func TestARepeatedRelocationInstallWritesNothingThroughWhatTheTenantPlanted(t *testing.T) { |
| 73 | for _, tc := range []struct { |
| 74 | name string |
| 75 | plant func(t *testing.T, f *installFixture, d string) |
| 76 | want error |
| 77 | }{ |
| 78 | {"a symlink at the files directory", func(t *testing.T, f *installFixture, d string) { |
| 79 | relink(t, f.paths().FilesDir, d) |
| 80 | }, instancefs.ErrSymlink}, |
| 81 | // Main's typed inventory refuses this one before any stage B write |
| 82 | // (the swap test below reaches the writes themselves). |
| 83 | {"a symlinked instance directory", func(t *testing.T, f *installFixture, d string) { |
| 84 | relink(t, filepath.Dir(f.paths().FilesDir), d) |
| 85 | }, nil}, |
| 86 | {"a FIFO at the files directory", func(t *testing.T, f *installFixture, _ string) { |
| 87 | p := f.paths().FilesDir |
| 88 | if err := os.RemoveAll(p); err != nil { |
| 89 | t.Fatal(err) |
| 90 | } |
| 91 | if err := syscall.Mkfifo(p, 0o600); err != nil { |
| 92 | t.Fatal(err) |
| 93 | } |
| 94 | }, nil}, |
| 95 | } { |
| 96 | t.Run(tc.name, func(t *testing.T) { |
| 97 | f := newInstallFixture(t, nil) |
| 98 | repeatInstall(t, f) |
| 99 | d := decoy(t) |
| 100 | tc.plant(t, f, d) |
| 101 | var err error |
| 102 | bounded(t, func() error { _, err = f.install(); return nil }) |
| 103 | if err == nil || (tc.want != nil && !errors.Is(err, tc.want)) { |
| 104 | t.Fatalf("install over a plant: %v; want %v", err, tc.want) |
| 105 | } |
| 106 | untouched(t, d) |
| 107 | if _, ok, _ := f.a.relocationReceipt(f.cfg)(t.Context(), f.read()); ok { |
| 108 | t.Fatal("a refused install left a receipt") |
| 109 | } |
| 110 | }) |
| 111 | } |
| 112 | } |
| 113 | |
| 114 | // The race the check-then-open left: a symlink renamed in after the |
| 115 | // install opened the files directory, or after it opened the instance |
| 116 | // directory's files root and before it writes the env file, is never |
| 117 | // followed. The restore lands in the directory that was opened; the env |
| 118 | // write and the env removal refuse a linked instance directory. |
| 119 | func TestARelocationInstallFollowsNoLinkSwappedInAfterItOpened(t *testing.T) { |
| 120 | t.Run("the files directory, between its check and its open", func(t *testing.T) { |
| 121 | f := newInstallFixture(t, nil) |
| 122 | repeatInstall(t, f) |
| 123 | files := f.paths().FilesDir |
| 124 | d := decoy(t) |
| 125 | swapOnce(t, "checked", func() { relink(t, files, d) }) |
| 126 | if _, err := f.install(); !errors.Is(err, instancefs.ErrSymlink) { |
| 127 | t.Fatalf("install after the files directory was linked: %v", err) |
| 128 | } |
| 129 | untouched(t, d) |
| 130 | }) |
| 131 | t.Run("the files directory, after its open", func(t *testing.T) { |
| 132 | f := newInstallFixture(t, nil) |
| 133 | repeatInstall(t, f) |
| 134 | files := f.paths().FilesDir |
| 135 | if err := os.RemoveAll(filepath.Join(files, "public")); err != nil { |
| 136 | t.Fatal(err) |
| 137 | } |
| 138 | d := decoy(t) |
| 139 | var moved string |
| 140 | swapOnce(t, "opened", func() { moved = relink(t, files, d) }) |
| 141 | if _, err := f.install(); err != nil { |
| 142 | t.Fatal(err) |
| 143 | } |
| 144 | untouched(t, d) |
| 145 | if _, err := os.Stat(filepath.Join(moved, "public", "index.html")); err != nil { |
| 146 | t.Fatalf("the restore did not land in the directory it opened: %v", err) |
| 147 | } |
| 148 | }) |
| 149 | for _, tc := range []struct { |
| 150 | name string |
| 151 | fixture func(t *testing.T) *installFixture |
| 152 | }{ |
| 153 | {"the env write", func(t *testing.T) *installFixture { return newInstallFixture(t, nil) }}, |
| 154 | {"the env removal", func(t *testing.T) *installFixture { return newInstallFixtureWith(t, buildOptions{NoFiles: true}) }}, |
| 155 | } { |
| 156 | t.Run(tc.name, func(t *testing.T) { |
| 157 | f := tc.fixture(t) |
| 158 | repeatInstall(t, f) |
| 159 | d := decoy(t) |
| 160 | swapOnce(t, "opened", func() { relink(t, filepath.Dir(f.paths().FilesDir), d) }) |
| 161 | if _, err := f.install(); !errors.Is(err, instancefs.ErrSymlink) { |
| 162 | t.Fatalf("install after the instance directory was linked: %v", err) |
| 163 | } |
| 164 | untouched(t, d) |
| 165 | }) |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | // swapOnce runs swap the first time the install or the flush reaches |
| 170 | // stage on the tenant's ground (tenantRootSeam), then never again. |
| 171 | func swapOnce(t *testing.T, stage string, swap func()) { |
| 172 | t.Helper() |
| 173 | done := false |
| 174 | prev := tenantRootSeam |
| 175 | tenantRootSeam = func(at string) { |
| 176 | if at == stage && !done { |
| 177 | done = true |
| 178 | swap() |
| 179 | } |
| 180 | } |
| 181 | t.Cleanup(func() { tenantRootSeam = prev }) |
| 182 | } |
| 183 | |
amadan