| 1 | //go:build linux |
| 2 | |
| 3 | package host |
| 4 | |
| 5 | import ( |
| 6 | "bytes" |
| 7 | "fmt" |
| 8 | "io" |
| 9 | "os" |
| 10 | "os/exec" |
| 11 | "os/user" |
| 12 | "path/filepath" |
| 13 | "runtime" |
| 14 | "strconv" |
| 15 | "strings" |
| 16 | "syscall" |
| 17 | "testing" |
| 18 | |
| 19 | "github.com/carlosframework/platform/internal/registry" |
| 20 | "golang.org/x/sys/unix" |
| 21 | ) |
| 22 | |
| 23 | func TestRegistryChildHardeningHelper(t *testing.T) { |
| 24 | if os.Args[len(os.Args)-1] != "--hardening-probe" { |
| 25 | return |
| 26 | } |
| 27 | if os.Geteuid() != 0 { |
| 28 | t.Fatal("child lost root before its in-process credential drop") |
| 29 | } |
| 30 | service, err := user.Lookup(serviceUser) |
| 31 | if err != nil { |
| 32 | t.Fatal(err) |
| 33 | } |
| 34 | uid, err := strconv.Atoi(service.Uid) |
| 35 | if err != nil { |
| 36 | t.Fatal(err) |
| 37 | } |
| 38 | gid, err := strconv.Atoi(service.Gid) |
| 39 | if err != nil { |
| 40 | t.Fatal(err) |
| 41 | } |
| 42 | // Malformed input must still drop all credentials and disable dumpability. |
| 43 | if err := RunRegistryChild(nil); err == nil { |
| 44 | t.Fatal("invalid arguments accepted") |
| 45 | } |
| 46 | ruid, euid, suid := unix.Getresuid() |
| 47 | rgid, egid, sgid := unix.Getresgid() |
| 48 | groups, err := os.Getgroups() |
| 49 | if err != nil || ruid != uid || euid != uid || suid != uid || rgid != gid || egid != gid || sgid != gid || len(groups) != 0 { |
| 50 | t.Fatalf("child credentials = uid %d:%d:%d, gid %d:%d:%d, groups %v: %v", ruid, euid, suid, rgid, egid, sgid, groups, err) |
| 51 | } |
| 52 | dumpable, err := unix.PrctlRetInt(unix.PR_GET_DUMPABLE, 0, 0, 0, 0) |
| 53 | if err != nil || dumpable != 0 { |
| 54 | t.Fatalf("dumpable = %d, %v", dumpable, err) |
| 55 | } |
| 56 | threads, err := os.ReadDir("/proc/self/task") |
| 57 | if err != nil { |
| 58 | t.Fatal(err) |
| 59 | } |
| 60 | for _, thread := range threads { |
| 61 | status, err := os.ReadFile(filepath.Join("/proc/self/task", thread.Name(), "status")) |
| 62 | if os.IsNotExist(err) { |
| 63 | continue |
| 64 | } |
| 65 | if err != nil || !bytes.Contains(status, []byte("NoNewPrivs:\t1\n")) { |
| 66 | t.Fatalf("thread %s lacks no-new-privileges: %v", thread.Name(), err) |
| 67 | } |
| 68 | for _, want := range []string{ |
| 69 | fmt.Sprintf("Uid:\t%d\t%d\t%d\t%d\n", uid, uid, uid, uid), |
| 70 | fmt.Sprintf("Gid:\t%d\t%d\t%d\t%d\n", gid, gid, gid, gid), |
| 71 | "Groups:\t\n", |
| 72 | } { |
| 73 | if !bytes.Contains(status, []byte(want)) { |
| 74 | t.Fatalf("thread %s lacks exact credentials %q: %s", thread.Name(), want, status) |
| 75 | } |
| 76 | } |
| 77 | } |
| 78 | if err := syscall.Setresuid(0, 0, 0); err == nil { |
| 79 | t.Fatal("child regained root uid") |
| 80 | } |
| 81 | if err := syscall.Setresgid(0, 0, 0); err == nil { |
| 82 | t.Fatal("child regained root gid") |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | func TestRegistryChildHardening(t *testing.T) { |
| 87 | if os.Geteuid() != 0 { |
| 88 | t.Skip("requires root to verify the child's in-process credential drop and dumpability") |
| 89 | } |
| 90 | if _, err := user.Lookup(serviceUser); err != nil { |
| 91 | t.Skip("requires the carlos service account") |
| 92 | } |
| 93 | // Keep this thread pinned while verifying the spawn did not change it. |
| 94 | runtime.LockOSThread() |
| 95 | defer runtime.UnlockOSThread() |
| 96 | before, err := unix.PrctlRetInt(unix.PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0) |
| 97 | if err != nil { |
| 98 | t.Fatal(err) |
| 99 | } |
| 100 | executable, err := os.Executable() |
| 101 | if err != nil { |
| 102 | t.Fatal(err) |
| 103 | } |
| 104 | cmd := exec.Command(executable, "-test.run=^TestRegistryChildHardeningHelper$", "--", "--hardening-probe") |
| 105 | var output bytes.Buffer |
| 106 | cmd.Stdout, cmd.Stderr = &output, &output |
| 107 | if err := registryChildStart(cmd); err != nil { |
| 108 | t.Fatal(err) |
| 109 | } |
| 110 | if err := cmd.Wait(); err != nil { |
| 111 | t.Fatalf("hardening probe: %v: %s", err, output.String()) |
| 112 | } |
| 113 | after, err := unix.PrctlRetInt(unix.PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0) |
| 114 | if err != nil || after != before { |
| 115 | t.Fatalf("parent no-new-privileges changed from %d to %d: %v", before, after, err) |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | func TestRegistryChildFDHelper(t *testing.T) { |
| 120 | if len(os.Args) == 0 || os.Args[len(os.Args)-1] != "--fd-probe" { |
| 121 | return |
| 122 | } |
| 123 | closeRegistryExecutable() |
| 124 | entries, err := os.ReadDir("/proc/self/fd") |
| 125 | if err != nil { |
| 126 | os.Exit(20) |
| 127 | } |
| 128 | for _, entry := range entries { |
| 129 | fd, err := strconv.Atoi(entry.Name()) |
| 130 | if err != nil || fd <= 2 { |
| 131 | continue |
| 132 | } |
| 133 | target, err := os.Readlink("/proc/self/fd/" + entry.Name()) |
| 134 | if os.IsNotExist(err) { |
| 135 | continue |
| 136 | } |
| 137 | if err != nil { |
| 138 | os.Exit(21) |
| 139 | } |
| 140 | if target != "anon_inode:[eventpoll]" && target != "anon_inode:[eventfd]" { |
| 141 | os.Exit(22) |
| 142 | } |
| 143 | } |
| 144 | os.Exit(0) |
| 145 | } |
| 146 | |
| 147 | func TestRegistryChildPinnedExecutableAndMinimalFDs(t *testing.T) { |
| 148 | dir := t.TempDir() |
| 149 | original, err := os.Open("/proc/self/exe") |
| 150 | if err != nil { |
| 151 | t.Fatal(err) |
| 152 | } |
| 153 | defer original.Close() |
| 154 | path := filepath.Join(dir, "worker") |
| 155 | destination, err := os.OpenFile(path, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0755) |
| 156 | if err != nil { |
| 157 | t.Fatal(err) |
| 158 | } |
| 159 | if _, err := io.Copy(destination, original); err != nil { |
| 160 | t.Fatal(err) |
| 161 | } |
| 162 | if err := destination.Close(); err != nil { |
| 163 | t.Fatal(err) |
| 164 | } |
| 165 | pinned, err := os.Open(path) |
| 166 | if err != nil { |
| 167 | t.Fatal(err) |
| 168 | } |
| 169 | defer pinned.Close() |
| 170 | saved, savedErr := registryExecutable, registryExecutableError |
| 171 | registryExecutable, registryExecutableError = pinned, nil |
| 172 | defer func() { registryExecutable, registryExecutableError = saved, savedErr }() |
| 173 | if err := os.Rename(path, path+".old"); err != nil { |
| 174 | t.Fatal(err) |
| 175 | } |
| 176 | if err := os.WriteFile(path, []byte("replacement is not executable"), 0755); err != nil { |
| 177 | t.Fatal(err) |
| 178 | } |
| 179 | inherited, err := os.OpenFile(filepath.Join(dir, "must-not-inherit"), os.O_CREATE|os.O_RDWR, 0600) |
| 180 | if err != nil { |
| 181 | t.Fatal(err) |
| 182 | } |
| 183 | defer inherited.Close() |
| 184 | if _, err := unix.FcntlInt(inherited.Fd(), unix.F_SETFD, 0); err != nil { |
| 185 | t.Fatal(err) |
| 186 | } |
| 187 | cmd, err := registryChildExec("unused", 65534, 65534) |
| 188 | if err != nil { |
| 189 | t.Fatal(err) |
| 190 | } |
| 191 | cmd.Args = []string{cmd.Path, "-test.run=^TestRegistryChildFDHelper$", "--", "--fd-probe"} |
| 192 | if err := registryChildCloseExec(); err != nil { |
| 193 | t.Fatal(err) |
| 194 | } |
| 195 | if output, err := cmd.CombinedOutput(); err != nil { |
| 196 | t.Fatalf("pinned child/fd probe: %v: %s", err, output) |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | func TestRegistryChildRealMainStartup(t *testing.T) { |
| 201 | if os.Geteuid() != 0 { |
| 202 | t.Skip("requires root to exercise the real service boundary") |
| 203 | } |
| 204 | service, err := user.Lookup(serviceUser) |
| 205 | if err != nil { |
| 206 | t.Skip("requires the carlos service account") |
| 207 | } |
| 208 | uid, err := strconv.Atoi(service.Uid) |
| 209 | if err != nil || uid <= 0 { |
| 210 | t.Fatal("invalid service uid") |
| 211 | } |
| 212 | gid, err := strconv.Atoi(service.Gid) |
| 213 | if err != nil { |
| 214 | t.Fatal(err) |
| 215 | } |
| 216 | dir, err := os.MkdirTemp(os.TempDir(), "registry-real-main-") |
| 217 | if err != nil { |
| 218 | t.Fatal(err) |
| 219 | } |
| 220 | defer os.RemoveAll(dir) |
| 221 | if err := os.Chmod(dir, 0755); err != nil { |
| 222 | t.Fatal(err) |
| 223 | } |
| 224 | path := filepath.Join(dir, "carlos") |
| 225 | build := exec.Command("go", "build", "-o", path, ".") |
| 226 | build.Dir = "../.." |
| 227 | if output, err := build.CombinedOutput(); err != nil { |
| 228 | t.Fatalf("build real main: %v: %s", err, output) |
| 229 | } |
| 230 | pinned, err := os.Open(path) |
| 231 | if err != nil { |
| 232 | t.Fatal(err) |
| 233 | } |
| 234 | defer pinned.Close() |
| 235 | saved, savedErr := registryExecutable, registryExecutableError |
| 236 | registryExecutable, registryExecutableError = pinned, nil |
| 237 | defer func() { registryExecutable, registryExecutableError = saved, savedErr }() |
| 238 | if err := os.Rename(path, path+".old"); err != nil { |
| 239 | t.Fatal(err) |
| 240 | } |
| 241 | if err := os.WriteFile(path, []byte("replacement"), 0755); err != nil { |
| 242 | t.Fatal(err) |
| 243 | } |
| 244 | data := filepath.Join(dir, "data") |
| 245 | if err := os.Mkdir(data, 0700); err != nil { |
| 246 | t.Fatal(err) |
| 247 | } |
| 248 | if err := os.Chown(data, uid, gid); err != nil { |
| 249 | t.Fatal(err) |
| 250 | } |
| 251 | dbPath := filepath.Join(data, "registry.db") |
| 252 | t.Setenv("CARLOS_HOST_CLAIM", "true") |
| 253 | r, err := openServiceRegistry(dbPath) |
| 254 | if err != nil { |
| 255 | t.Fatal(err) |
| 256 | } |
| 257 | defer r.Close() |
| 258 | if err := r.Upsert(registry.Route{Host: "real-main", Kind: "instance"}); err != nil { |
| 259 | t.Fatal(err) |
| 260 | } |
| 261 | for _, suffix := range []string{"", "-wal", "-shm"} { |
| 262 | info, err := os.Stat(dbPath + suffix) |
| 263 | if err != nil { |
| 264 | t.Fatal(err) |
| 265 | } |
| 266 | gotUID, gotGID, ok := fileOwner(info) |
| 267 | if !ok || gotUID != uid || gotGID != gid { |
| 268 | t.Fatalf("%s owner = %d:%d", strings.TrimPrefix(dbPath+suffix, dir), gotUID, gotGID) |
| 269 | } |
| 270 | } |
| 271 | } |
| 272 | |
amadan