github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/syscall/exec_linux_test.go (about) 1 // Copyright 2015 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 //go:build linux 6 7 package syscall_test 8 9 import ( 10 "bytes" 11 "flag" 12 "fmt" 13 "internal/testenv" 14 "io" 15 "os" 16 "os/exec" 17 "os/user" 18 "path" 19 "path/filepath" 20 "runtime" 21 "strconv" 22 "strings" 23 "syscall" 24 "testing" 25 "unsafe" 26 ) 27 28 // whoamiNEWUSER returns a command that runs "whoami" with CLONE_NEWUSER, 29 // mapping uid and gid 0 to the actual uid and gid of the test. 30 func whoamiNEWUSER(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd { 31 t.Helper() 32 testenv.MustHaveExecPath(t, "whoami") 33 cmd := testenv.Command(t, "whoami") 34 cmd.SysProcAttr = &syscall.SysProcAttr{ 35 Cloneflags: syscall.CLONE_NEWUSER, 36 UidMappings: []syscall.SysProcIDMap{ 37 {ContainerID: 0, HostID: uid, Size: 1}, 38 }, 39 GidMappings: []syscall.SysProcIDMap{ 40 {ContainerID: 0, HostID: gid, Size: 1}, 41 }, 42 GidMappingsEnableSetgroups: setgroups, 43 } 44 return cmd 45 } 46 47 func TestCloneNEWUSERAndRemap(t *testing.T) { 48 for _, setgroups := range []bool{false, true} { 49 setgroups := setgroups 50 t.Run(fmt.Sprintf("setgroups=%v", setgroups), func(t *testing.T) { 51 uid := os.Getuid() 52 gid := os.Getgid() 53 54 cmd := whoamiNEWUSER(t, uid, gid, setgroups) 55 out, err := cmd.CombinedOutput() 56 t.Logf("%v: %v", cmd, err) 57 58 if uid != 0 && setgroups { 59 t.Logf("as non-root, expected permission error due to unprivileged gid_map") 60 if !os.IsPermission(err) { 61 if err == nil { 62 t.Skipf("unexpected success: probably old kernel without security fix?") 63 } 64 if testenv.SyscallIsNotSupported(err) { 65 t.Skipf("skipping: CLONE_NEWUSER appears to be unsupported") 66 } 67 t.Fatalf("got non-permission error") // Already logged above. 68 } 69 return 70 } 71 72 if err != nil { 73 if testenv.SyscallIsNotSupported(err) { 74 // May be inside a container that disallows CLONE_NEWUSER. 75 t.Skipf("skipping: CLONE_NEWUSER appears to be unsupported") 76 } 77 t.Fatalf("unexpected command failure; output:\n%s", out) 78 } 79 80 sout := strings.TrimSpace(string(out)) 81 want := "root" 82 if sout != want { 83 t.Fatalf("whoami = %q; want %q", out, want) 84 } 85 }) 86 } 87 } 88 89 func TestEmptyCredGroupsDisableSetgroups(t *testing.T) { 90 cmd := whoamiNEWUSER(t, os.Getuid(), os.Getgid(), false) 91 cmd.SysProcAttr.Credential = &syscall.Credential{} 92 if err := cmd.Run(); err != nil { 93 if testenv.SyscallIsNotSupported(err) { 94 t.Skipf("skipping: %v: %v", cmd, err) 95 } 96 t.Fatal(err) 97 } 98 } 99 100 func TestUnshare(t *testing.T) { 101 path := "/proc/net/dev" 102 if _, err := os.Stat(path); err != nil { 103 if os.IsNotExist(err) { 104 t.Skip("kernel doesn't support proc filesystem") 105 } 106 if os.IsPermission(err) { 107 t.Skip("unable to test proc filesystem due to permissions") 108 } 109 t.Fatal(err) 110 } 111 112 orig, err := os.ReadFile(path) 113 if err != nil { 114 t.Fatal(err) 115 } 116 origLines := strings.Split(strings.TrimSpace(string(orig)), "\n") 117 118 cmd := testenv.Command(t, "cat", path) 119 cmd.SysProcAttr = &syscall.SysProcAttr{ 120 Unshareflags: syscall.CLONE_NEWNET, 121 } 122 out, err := cmd.CombinedOutput() 123 if err != nil { 124 if testenv.SyscallIsNotSupported(err) { 125 // CLONE_NEWNET does not appear to be supported. 126 t.Skipf("skipping due to permission error: %v", err) 127 } 128 t.Fatalf("Cmd failed with err %v, output: %s", err, out) 129 } 130 131 // Check there is only the local network interface 132 sout := strings.TrimSpace(string(out)) 133 if !strings.Contains(sout, "lo:") { 134 t.Fatalf("Expected lo network interface to exist, got %s", sout) 135 } 136 137 lines := strings.Split(sout, "\n") 138 if len(lines) >= len(origLines) { 139 t.Fatalf("Got %d lines of output, want <%d", len(lines), len(origLines)) 140 } 141 } 142 143 func TestGroupCleanup(t *testing.T) { 144 testenv.MustHaveExecPath(t, "id") 145 cmd := testenv.Command(t, "id") 146 cmd.SysProcAttr = &syscall.SysProcAttr{ 147 Credential: &syscall.Credential{ 148 Uid: 0, 149 Gid: 0, 150 }, 151 } 152 out, err := cmd.CombinedOutput() 153 if err != nil { 154 if testenv.SyscallIsNotSupported(err) { 155 t.Skipf("skipping: %v: %v", cmd, err) 156 } 157 t.Fatalf("Cmd failed with err %v, output: %s", err, out) 158 } 159 strOut := strings.TrimSpace(string(out)) 160 t.Logf("id: %s", strOut) 161 162 expected := "uid=0(root) gid=0(root)" 163 // Just check prefix because some distros reportedly output a 164 // context parameter; see https://golang.org/issue/16224. 165 // Alpine does not output groups; see https://golang.org/issue/19938. 166 if !strings.HasPrefix(strOut, expected) { 167 t.Errorf("expected prefix: %q", expected) 168 } 169 } 170 171 func TestGroupCleanupUserNamespace(t *testing.T) { 172 testenv.MustHaveExecPath(t, "id") 173 cmd := testenv.Command(t, "id") 174 uid, gid := os.Getuid(), os.Getgid() 175 cmd.SysProcAttr = &syscall.SysProcAttr{ 176 Cloneflags: syscall.CLONE_NEWUSER, 177 Credential: &syscall.Credential{ 178 Uid: uint32(uid), 179 Gid: uint32(gid), 180 }, 181 UidMappings: []syscall.SysProcIDMap{ 182 {ContainerID: 0, HostID: uid, Size: 1}, 183 }, 184 GidMappings: []syscall.SysProcIDMap{ 185 {ContainerID: 0, HostID: gid, Size: 1}, 186 }, 187 } 188 out, err := cmd.CombinedOutput() 189 if err != nil { 190 if testenv.SyscallIsNotSupported(err) { 191 t.Skipf("skipping: %v: %v", cmd, err) 192 } 193 t.Fatalf("Cmd failed with err %v, output: %s", err, out) 194 } 195 strOut := strings.TrimSpace(string(out)) 196 t.Logf("id: %s", strOut) 197 198 // As in TestGroupCleanup, just check prefix. 199 // The actual groups and contexts seem to vary from one distro to the next. 200 expected := "uid=0(root) gid=0(root) groups=0(root)" 201 if !strings.HasPrefix(strOut, expected) { 202 t.Errorf("expected prefix: %q", expected) 203 } 204 } 205 206 // Test for https://go.dev/issue/19661: unshare fails because systemd 207 // has forced / to be shared 208 func TestUnshareMountNameSpace(t *testing.T) { 209 testenv.MustHaveExec(t) 210 211 if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" { 212 dir := flag.Args()[0] 213 err := syscall.Mount("none", dir, "proc", 0, "") 214 if err != nil { 215 fmt.Fprintf(os.Stderr, "unshare: mount %v failed: %#v", dir, err) 216 os.Exit(2) 217 } 218 os.Exit(0) 219 } 220 221 exe, err := os.Executable() 222 if err != nil { 223 t.Fatal(err) 224 } 225 226 d := t.TempDir() 227 t.Cleanup(func() { 228 // If the subprocess fails to unshare the parent directory, force-unmount it 229 // so that the test can clean it up. 230 if _, err := os.Stat(d); err == nil { 231 syscall.Unmount(d, syscall.MNT_FORCE) 232 } 233 }) 234 cmd := testenv.Command(t, exe, "-test.run=TestUnshareMountNameSpace", d) 235 cmd.Env = append(cmd.Environ(), "GO_WANT_HELPER_PROCESS=1") 236 cmd.SysProcAttr = &syscall.SysProcAttr{Unshareflags: syscall.CLONE_NEWNS} 237 238 o, err := cmd.CombinedOutput() 239 if err != nil { 240 if testenv.SyscallIsNotSupported(err) { 241 t.Skipf("skipping: could not start process with CLONE_NEWNS: %v", err) 242 } 243 t.Fatalf("unshare failed: %v\n%s", err, o) 244 } 245 246 // How do we tell if the namespace was really unshared? It turns out 247 // to be simple: just try to remove the directory. If it's still mounted 248 // on the rm will fail with EBUSY. 249 if err := os.Remove(d); err != nil { 250 t.Errorf("rmdir failed on %v: %v", d, err) 251 } 252 } 253 254 // Test for Issue 20103: unshare fails when chroot is used 255 func TestUnshareMountNameSpaceChroot(t *testing.T) { 256 if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" { 257 dir := flag.Args()[0] 258 err := syscall.Mount("none", dir, "proc", 0, "") 259 if err != nil { 260 fmt.Fprintf(os.Stderr, "unshare: mount %v failed: %#v", dir, err) 261 os.Exit(2) 262 } 263 os.Exit(0) 264 } 265 266 d := t.TempDir() 267 268 // Since we are doing a chroot, we need the binary there, 269 // and it must be statically linked. 270 testenv.MustHaveGoBuild(t) 271 x := filepath.Join(d, "syscall.test") 272 t.Cleanup(func() { 273 // If the subprocess fails to unshare the parent directory, force-unmount it 274 // so that the test can clean it up. 275 if _, err := os.Stat(d); err == nil { 276 syscall.Unmount(d, syscall.MNT_FORCE) 277 } 278 }) 279 280 cmd := testenv.Command(t, testenv.GoToolPath(t), "test", "-c", "-o", x, "syscall") 281 cmd.Env = append(cmd.Environ(), "CGO_ENABLED=0") 282 if o, err := cmd.CombinedOutput(); err != nil { 283 t.Fatalf("Build of syscall in chroot failed, output %v, err %v", o, err) 284 } 285 286 cmd = testenv.Command(t, "/syscall.test", "-test.run=TestUnshareMountNameSpaceChroot", "/") 287 cmd.Env = append(cmd.Environ(), "GO_WANT_HELPER_PROCESS=1") 288 cmd.SysProcAttr = &syscall.SysProcAttr{Chroot: d, Unshareflags: syscall.CLONE_NEWNS} 289 290 o, err := cmd.CombinedOutput() 291 if err != nil { 292 if testenv.SyscallIsNotSupported(err) { 293 t.Skipf("skipping: could not start process with CLONE_NEWNS and Chroot %q: %v", d, err) 294 } 295 t.Fatalf("unshare failed: %v\n%s", err, o) 296 } 297 298 // How do we tell if the namespace was really unshared? It turns out 299 // to be simple: just try to remove the executable. If it's still mounted 300 // on, the rm will fail. 301 if err := os.Remove(x); err != nil { 302 t.Errorf("rm failed on %v: %v", x, err) 303 } 304 if err := os.Remove(d); err != nil { 305 t.Errorf("rmdir failed on %v: %v", d, err) 306 } 307 } 308 309 // Test for Issue 29789: unshare fails when uid/gid mapping is specified 310 func TestUnshareUidGidMapping(t *testing.T) { 311 if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" { 312 defer os.Exit(0) 313 if err := syscall.Chroot(os.TempDir()); err != nil { 314 fmt.Fprintln(os.Stderr, err) 315 os.Exit(2) 316 } 317 } 318 319 if os.Getuid() == 0 { 320 t.Skip("test exercises unprivileged user namespace, fails with privileges") 321 } 322 323 testenv.MustHaveExec(t) 324 exe, err := os.Executable() 325 if err != nil { 326 t.Fatal(err) 327 } 328 329 cmd := testenv.Command(t, exe, "-test.run=TestUnshareUidGidMapping") 330 cmd.Env = append(cmd.Environ(), "GO_WANT_HELPER_PROCESS=1") 331 cmd.SysProcAttr = &syscall.SysProcAttr{ 332 Unshareflags: syscall.CLONE_NEWNS | syscall.CLONE_NEWUSER, 333 GidMappingsEnableSetgroups: false, 334 UidMappings: []syscall.SysProcIDMap{ 335 { 336 ContainerID: 0, 337 HostID: syscall.Getuid(), 338 Size: 1, 339 }, 340 }, 341 GidMappings: []syscall.SysProcIDMap{ 342 { 343 ContainerID: 0, 344 HostID: syscall.Getgid(), 345 Size: 1, 346 }, 347 }, 348 } 349 out, err := cmd.CombinedOutput() 350 if err != nil { 351 if testenv.SyscallIsNotSupported(err) { 352 t.Skipf("skipping: could not start process with CLONE_NEWNS and CLONE_NEWUSER: %v", err) 353 } 354 t.Fatalf("Cmd failed with err %v, output: %s", err, out) 355 } 356 } 357 358 func prepareCgroupFD(t *testing.T) (int, string) { 359 t.Helper() 360 361 const O_PATH = 0x200000 // Same for all architectures, but for some reason not defined in syscall for 386||amd64. 362 363 // Requires cgroup v2. 364 const prefix = "/sys/fs/cgroup" 365 selfCg, err := os.ReadFile("/proc/self/cgroup") 366 if err != nil { 367 if os.IsNotExist(err) || os.IsPermission(err) { 368 t.Skip(err) 369 } 370 t.Fatal(err) 371 } 372 373 // Expect a single line like this: 374 // 0::/user.slice/user-1000.slice/user@1000.service/app.slice/vte-spawn-891992a2-efbb-4f28-aedb-b24f9e706770.scope 375 // Otherwise it's either cgroup v1 or a hybrid hierarchy. 376 if bytes.Count(selfCg, []byte("\n")) > 1 { 377 t.Skip("cgroup v2 not available") 378 } 379 cg := bytes.TrimPrefix(selfCg, []byte("0::")) 380 if len(cg) == len(selfCg) { // No prefix found. 381 t.Skipf("cgroup v2 not available (/proc/self/cgroup contents: %q)", selfCg) 382 } 383 384 // Need clone3 with CLONE_INTO_CGROUP support. 385 _, err = syscall.ForkExec("non-existent binary", nil, &syscall.ProcAttr{ 386 Sys: &syscall.SysProcAttr{ 387 UseCgroupFD: true, 388 CgroupFD: -1, 389 }, 390 }) 391 if testenv.SyscallIsNotSupported(err) { 392 t.Skipf("clone3 with CLONE_INTO_CGROUP not available: %v", err) 393 } 394 395 // Need an ability to create a sub-cgroup. 396 subCgroup, err := os.MkdirTemp(prefix+string(bytes.TrimSpace(cg)), "subcg-") 397 if err != nil { 398 // ErrPermission or EROFS (#57262) when running in an unprivileged container. 399 // ErrNotExist when cgroupfs is not mounted in chroot/schroot. 400 if os.IsNotExist(err) || testenv.SyscallIsNotSupported(err) { 401 t.Skipf("skipping: %v", err) 402 } 403 t.Fatal(err) 404 } 405 t.Cleanup(func() { syscall.Rmdir(subCgroup) }) 406 407 cgroupFD, err := syscall.Open(subCgroup, O_PATH, 0) 408 if err != nil { 409 t.Fatal(&os.PathError{Op: "open", Path: subCgroup, Err: err}) 410 } 411 t.Cleanup(func() { syscall.Close(cgroupFD) }) 412 413 return cgroupFD, "/" + path.Base(subCgroup) 414 } 415 416 func TestUseCgroupFD(t *testing.T) { 417 testenv.MustHaveExec(t) 418 exe, err := os.Executable() 419 if err != nil { 420 t.Fatal(err) 421 } 422 423 fd, suffix := prepareCgroupFD(t) 424 425 cmd := testenv.Command(t, exe, "-test.run=TestUseCgroupFDHelper") 426 cmd.Env = append(cmd.Environ(), "GO_WANT_HELPER_PROCESS=1") 427 cmd.SysProcAttr = &syscall.SysProcAttr{ 428 UseCgroupFD: true, 429 CgroupFD: fd, 430 } 431 out, err := cmd.CombinedOutput() 432 if err != nil { 433 t.Fatalf("Cmd failed with err %v, output: %s", err, out) 434 } 435 // NB: this wouldn't work with cgroupns. 436 if !bytes.HasSuffix(bytes.TrimSpace(out), []byte(suffix)) { 437 t.Fatalf("got: %q, want: a line that ends with %q", out, suffix) 438 } 439 } 440 441 func TestUseCgroupFDHelper(*testing.T) { 442 if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" { 443 return 444 } 445 defer os.Exit(0) 446 // Read and print own cgroup path. 447 selfCg, err := os.ReadFile("/proc/self/cgroup") 448 if err != nil { 449 fmt.Fprintln(os.Stderr, err) 450 os.Exit(2) 451 } 452 fmt.Print(string(selfCg)) 453 } 454 455 func TestCloneTimeNamespace(t *testing.T) { 456 testenv.MustHaveExec(t) 457 458 if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" { 459 timens, err := os.Readlink("/proc/self/ns/time") 460 if err != nil { 461 fmt.Fprintln(os.Stderr, err) 462 os.Exit(2) 463 } 464 fmt.Print(string(timens)) 465 os.Exit(0) 466 } 467 468 exe, err := os.Executable() 469 if err != nil { 470 t.Fatal(err) 471 } 472 473 cmd := testenv.Command(t, exe, "-test.run=TestCloneTimeNamespace") 474 cmd.Env = append(cmd.Environ(), "GO_WANT_HELPER_PROCESS=1") 475 cmd.SysProcAttr = &syscall.SysProcAttr{ 476 Cloneflags: syscall.CLONE_NEWTIME, 477 } 478 out, err := cmd.CombinedOutput() 479 if err != nil { 480 if testenv.SyscallIsNotSupported(err) { 481 // CLONE_NEWTIME does not appear to be supported. 482 t.Skipf("skipping, CLONE_NEWTIME not supported: %v", err) 483 } 484 t.Fatalf("Cmd failed with err %v, output: %s", err, out) 485 } 486 487 // Inode numer of the time namespaces should be different. 488 // Based on https://man7.org/linux/man-pages/man7/time_namespaces.7.html#EXAMPLES 489 timens, err := os.Readlink("/proc/self/ns/time") 490 if err != nil { 491 t.Fatal(err) 492 } 493 494 parentTimeNS := string(timens) 495 childTimeNS := string(out) 496 if childTimeNS == parentTimeNS { 497 t.Fatalf("expected child time namespace to be different from parent time namespace: %s", parentTimeNS) 498 } 499 } 500 501 type capHeader struct { 502 version uint32 503 pid int32 504 } 505 506 type capData struct { 507 effective uint32 508 permitted uint32 509 inheritable uint32 510 } 511 512 const CAP_SYS_TIME = 25 513 const CAP_SYSLOG = 34 514 515 type caps struct { 516 hdr capHeader 517 data [2]capData 518 } 519 520 func getCaps() (caps, error) { 521 var c caps 522 523 // Get capability version 524 if _, _, errno := syscall.Syscall(syscall.SYS_CAPGET, uintptr(unsafe.Pointer(&c.hdr)), uintptr(unsafe.Pointer(nil)), 0); errno != 0 { 525 return c, fmt.Errorf("SYS_CAPGET: %v", errno) 526 } 527 528 // Get current capabilities 529 if _, _, errno := syscall.Syscall(syscall.SYS_CAPGET, uintptr(unsafe.Pointer(&c.hdr)), uintptr(unsafe.Pointer(&c.data[0])), 0); errno != 0 { 530 return c, fmt.Errorf("SYS_CAPGET: %v", errno) 531 } 532 533 return c, nil 534 } 535 536 func TestAmbientCaps(t *testing.T) { 537 testAmbientCaps(t, false) 538 } 539 540 func TestAmbientCapsUserns(t *testing.T) { 541 testAmbientCaps(t, true) 542 } 543 544 func testAmbientCaps(t *testing.T, userns bool) { 545 if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" { 546 caps, err := getCaps() 547 if err != nil { 548 fmt.Fprintln(os.Stderr, err) 549 os.Exit(2) 550 } 551 if caps.data[0].effective&(1<<uint(CAP_SYS_TIME)) == 0 { 552 fmt.Fprintln(os.Stderr, "CAP_SYS_TIME unexpectedly not in the effective capability mask") 553 os.Exit(2) 554 } 555 if caps.data[1].effective&(1<<uint(CAP_SYSLOG&31)) == 0 { 556 fmt.Fprintln(os.Stderr, "CAP_SYSLOG unexpectedly not in the effective capability mask") 557 os.Exit(2) 558 } 559 os.Exit(0) 560 } 561 562 // skip on android, due to lack of lookup support 563 if runtime.GOOS == "android" { 564 t.Skip("skipping test on android; see Issue 27327") 565 } 566 567 u, err := user.Lookup("nobody") 568 if err != nil { 569 t.Fatal(err) 570 } 571 uid, err := strconv.ParseInt(u.Uid, 0, 32) 572 if err != nil { 573 t.Fatal(err) 574 } 575 gid, err := strconv.ParseInt(u.Gid, 0, 32) 576 if err != nil { 577 t.Fatal(err) 578 } 579 580 // Copy the test binary to a temporary location which is readable by nobody. 581 f, err := os.CreateTemp("", "gotest") 582 if err != nil { 583 t.Fatal(err) 584 } 585 t.Cleanup(func() { 586 f.Close() 587 os.Remove(f.Name()) 588 }) 589 590 testenv.MustHaveExec(t) 591 exe, err := os.Executable() 592 if err != nil { 593 t.Fatal(err) 594 } 595 596 e, err := os.Open(exe) 597 if err != nil { 598 t.Fatal(err) 599 } 600 defer e.Close() 601 if _, err := io.Copy(f, e); err != nil { 602 t.Fatal(err) 603 } 604 if err := f.Chmod(0755); err != nil { 605 t.Fatal(err) 606 } 607 if err := f.Close(); err != nil { 608 t.Fatal(err) 609 } 610 611 cmd := testenv.Command(t, f.Name(), "-test.run="+t.Name()) 612 cmd.Env = append(cmd.Environ(), "GO_WANT_HELPER_PROCESS=1") 613 cmd.Stdout = os.Stdout 614 cmd.Stderr = os.Stderr 615 cmd.SysProcAttr = &syscall.SysProcAttr{ 616 Credential: &syscall.Credential{ 617 Uid: uint32(uid), 618 Gid: uint32(gid), 619 }, 620 AmbientCaps: []uintptr{CAP_SYS_TIME, CAP_SYSLOG}, 621 } 622 if userns { 623 cmd.SysProcAttr.Cloneflags = syscall.CLONE_NEWUSER 624 const nobody = 65534 625 uid := os.Getuid() 626 gid := os.Getgid() 627 cmd.SysProcAttr.UidMappings = []syscall.SysProcIDMap{{ 628 ContainerID: int(nobody), 629 HostID: int(uid), 630 Size: int(1), 631 }} 632 cmd.SysProcAttr.GidMappings = []syscall.SysProcIDMap{{ 633 ContainerID: int(nobody), 634 HostID: int(gid), 635 Size: int(1), 636 }} 637 638 // Set credentials to run as user and group nobody. 639 cmd.SysProcAttr.Credential = &syscall.Credential{ 640 Uid: nobody, 641 Gid: nobody, 642 } 643 } 644 if err := cmd.Run(); err != nil { 645 if testenv.SyscallIsNotSupported(err) { 646 t.Skipf("skipping: %v: %v", cmd, err) 647 } 648 t.Fatal(err.Error()) 649 } 650 }