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syscall: add support for SysProcAttr.Pdeathsig on FreeBSD 

Fixes #46258

Change-Id: I63f70e67274a9df39c757243b99b12e50a9e4784
Reviewed-on: https://go-review.googlesource.com/c/go/+/355570
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Tobias Klauser 2021-10-13 16:30:12 +02:00 committed by Tobias Klauser
parent 1349c6eb1e
commit 2feb2cc450
5 changed files with 184 additions and 119 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
src/syscall/exec_freebsd.go
View File

@ -5,6 +5,7 @@
package syscall
import (
"runtime"
"unsafe"
)
@ -29,9 +30,16 @@ type SysProcAttr struct {
// Unlike Setctty, in this case Ctty must be a descriptor
// number in the parent process.
Foreground bool
Pgid int // Child's process group ID if Setpgid.
Pgid int // Child's process group ID if Setpgid.
Pdeathsig Signal // Signal that the process will get when its parent dies (Linux and FreeBSD only)
}
const (
_P_PID = 0
_PROC_PDEATHSIG_CTL = 11
)
// Implemented in runtime package.
func runtime_BeforeFork()
func runtime_AfterFork()
@ -57,6 +65,9 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
i int
)
// Record parent PID so child can test if it has died.
ppid, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
// guard against side effects of shuffling fds below.
// Make sure that nextfd is beyond any currently open files so
// that we can't run the risk of overwriting any of them.
@ -175,6 +186,31 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
}
}
// Parent death signal
if sys.Pdeathsig != 0 {
switch runtime.GOARCH {
case "386", "arm":
_, _, err1 = RawSyscall6(SYS_PROCCTL, _P_PID, 0, 0, _PROC_PDEATHSIG_CTL, uintptr(unsafe.Pointer(&sys.Pdeathsig)), 0)
default:
_, _, err1 = RawSyscall6(SYS_PROCCTL, _P_PID, 0, _PROC_PDEATHSIG_CTL, uintptr(unsafe.Pointer(&sys.Pdeathsig)), 0, 0)
}
if err1 != 0 {
goto childerror
}
// Signal self if parent is already dead. This might cause a
// duplicate signal in rare cases, but it won't matter when
// using SIGKILL.
r1, _, _ = RawSyscall(SYS_GETPPID, 0, 0, 0)
if r1 != ppid {
pid, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
_, _, err1 := RawSyscall(SYS_KILL, pid, uintptr(sys.Pdeathsig), 0)
if err1 != 0 {
goto childerror
}
}
}
// Pass 1: look for fd[i] < i and move those up above len(fd)
// so that pass 2 won't stomp on an fd it needs later.
if pipe < nextfd {

2
src/syscall/exec_linux.go
View File

@ -46,7 +46,7 @@ type SysProcAttr struct {
// number in the parent process.
Foreground bool
Pgid int // Child's process group ID if Setpgid.
Pdeathsig Signal // Signal that the process will get when its parent dies (Linux only)
Pdeathsig Signal // Signal that the process will get when its parent dies (Linux and FreeBSD only)
Cloneflags uintptr // Flags for clone calls (Linux only)
Unshareflags uintptr // Flags for unshare calls (Linux only)
UidMappings []SysProcIDMap // User ID mappings for user namespaces.

135
src/syscall/exec_pdeathsig_test.go Normal file
View File

@ -0,0 +1,135 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build freebsd || linux
// +build freebsd linux
package syscall_test
import (
"bufio"
"fmt"
"io"
"os"
"os/exec"
"os/signal"
"path/filepath"
"syscall"
"testing"
"time"
)
func TestDeathSignal(t *testing.T) {
if os.Getuid() != 0 {
t.Skip("skipping root only test")
}
// Copy the test binary to a location that a non-root user can read/execute
// after we drop privileges
tempDir, err := os.MkdirTemp("", "TestDeathSignal")
if err != nil {
t.Fatalf("cannot create temporary directory: %v", err)
}
defer os.RemoveAll(tempDir)
os.Chmod(tempDir, 0755)
tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
src, err := os.Open(os.Args[0])
if err != nil {
t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
}
defer src.Close()
dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
if err != nil {
t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
}
if _, err := io.Copy(dst, src); err != nil {
t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
}
err = dst.Close()
if err != nil {
t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
}
cmd := exec.Command(tmpBinary)
cmd.Env = append(os.Environ(), "GO_DEATHSIG_PARENT=1")
chldStdin, err := cmd.StdinPipe()
if err != nil {
t.Fatalf("failed to create new stdin pipe: %v", err)
}
chldStdout, err := cmd.StdoutPipe()
if err != nil {
t.Fatalf("failed to create new stdout pipe: %v", err)
}
cmd.Stderr = os.Stderr
err = cmd.Start()
defer cmd.Wait()
if err != nil {
t.Fatalf("failed to start first child process: %v", err)
}
chldPipe := bufio.NewReader(chldStdout)
if got, err := chldPipe.ReadString('\n'); got == "start\n" {
syscall.Kill(cmd.Process.Pid, syscall.SIGTERM)
go func() {
time.Sleep(5 * time.Second)
chldStdin.Close()
}()
want := "ok\n"
if got, err = chldPipe.ReadString('\n'); got != want {
t.Fatalf("expected %q, received %q, %v", want, got, err)
}
} else {
t.Fatalf("did not receive start from child, received %q, %v", got, err)
}
}
func deathSignalParent() {
cmd := exec.Command(os.Args[0])
cmd.Env = append(os.Environ(),
"GO_DEATHSIG_PARENT=",
"GO_DEATHSIG_CHILD=1",
)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
attrs := syscall.SysProcAttr{
Pdeathsig: syscall.SIGUSR1,
// UID/GID 99 is the user/group "nobody" on RHEL/Fedora and is
// unused on Ubuntu
Credential: &syscall.Credential{Uid: 99, Gid: 99},
}
cmd.SysProcAttr = &attrs
err := cmd.Start()
if err != nil {
fmt.Fprintf(os.Stderr, "death signal parent error: %v\n", err)
os.Exit(1)
}
cmd.Wait()
os.Exit(0)
}
func deathSignalChild() {
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGUSR1)
go func() {
<-c
fmt.Println("ok")
os.Exit(0)
}()
fmt.Println("start")
buf := make([]byte, 32)
os.Stdin.Read(buf)
// We expected to be signaled before stdin closed
fmt.Println("not ok")
os.Exit(1)
}

11
src/syscall/syscall_freebsd_test.go
View File

@ -9,6 +9,7 @@ package syscall_test
import (
"fmt"
"os"
"syscall"
"testing"
"unsafe"
@ -53,3 +54,13 @@ func TestConvertFromDirent11(t *testing.T) {
}
}
}
func TestMain(m *testing.M) {
if os.Getenv("GO_DEATHSIG_PARENT") == "1" {
deathSignalParent()
} else if os.Getenv("GO_DEATHSIG_CHILD") == "1" {
deathSignalChild()
}
os.Exit(m.Run())
}

117
src/syscall/syscall_linux_test.go
View File

@ -5,13 +5,11 @@
package syscall_test
import (
"bufio"
"fmt"
"io"
"io/fs"
"os"
"os/exec"
"os/signal"
"path/filepath"
"runtime"
"sort"
@ -19,7 +17,6 @@ import (
"strings"
"syscall"
"testing"
"time"
"unsafe"
)
@ -153,120 +150,6 @@ func TestMain(m *testing.M) {
os.Exit(m.Run())
}
func TestLinuxDeathSignal(t *testing.T) {
if os.Getuid() != 0 {
t.Skip("skipping root only test")
}
// Copy the test binary to a location that a non-root user can read/execute
// after we drop privileges
tempDir, err := os.MkdirTemp("", "TestDeathSignal")
if err != nil {
t.Fatalf("cannot create temporary directory: %v", err)
}
defer os.RemoveAll(tempDir)
os.Chmod(tempDir, 0755)
tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
src, err := os.Open(os.Args[0])
if err != nil {
t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
}
defer src.Close()
dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
if err != nil {
t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
}
if _, err := io.Copy(dst, src); err != nil {
t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
}
err = dst.Close()
if err != nil {
t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
}
cmd := exec.Command(tmpBinary)
cmd.Env = append(os.Environ(), "GO_DEATHSIG_PARENT=1")
chldStdin, err := cmd.StdinPipe()
if err != nil {
t.Fatalf("failed to create new stdin pipe: %v", err)
}
chldStdout, err := cmd.StdoutPipe()
if err != nil {
t.Fatalf("failed to create new stdout pipe: %v", err)
}
cmd.Stderr = os.Stderr
err = cmd.Start()
defer cmd.Wait()
if err != nil {
t.Fatalf("failed to start first child process: %v", err)
}
chldPipe := bufio.NewReader(chldStdout)
if got, err := chldPipe.ReadString('\n'); got == "start\n" {
syscall.Kill(cmd.Process.Pid, syscall.SIGTERM)
go func() {
time.Sleep(5 * time.Second)
chldStdin.Close()
}()
want := "ok\n"
if got, err = chldPipe.ReadString('\n'); got != want {
t.Fatalf("expected %q, received %q, %v", want, got, err)
}
} else {
t.Fatalf("did not receive start from child, received %q, %v", got, err)
}
}
func deathSignalParent() {
cmd := exec.Command(os.Args[0])
cmd.Env = append(os.Environ(),
"GO_DEATHSIG_PARENT=",
"GO_DEATHSIG_CHILD=1",
)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
attrs := syscall.SysProcAttr{
Pdeathsig: syscall.SIGUSR1,
// UID/GID 99 is the user/group "nobody" on RHEL/Fedora and is
// unused on Ubuntu
Credential: &syscall.Credential{Uid: 99, Gid: 99},
}
cmd.SysProcAttr = &attrs
err := cmd.Start()
if err != nil {
fmt.Fprintf(os.Stderr, "death signal parent error: %v\n", err)
os.Exit(1)
}
cmd.Wait()
os.Exit(0)
}
func deathSignalChild() {
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGUSR1)
go func() {
<-c
fmt.Println("ok")
os.Exit(0)
}()
fmt.Println("start")
buf := make([]byte, 32)
os.Stdin.Read(buf)
// We expected to be signaled before stdin closed
fmt.Println("not ok")
os.Exit(1)
}
func TestParseNetlinkMessage(t *testing.T) {
for i, b := range [][]byte{
{103, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 5, 8, 0, 3,