282 lines
6.5 KiB
Go
282 lines
6.5 KiB
Go
// Copyright 2011 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 aix || darwin || dragonfly || netbsd || openbsd || solaris
|
|
|
|
package syscall
|
|
|
|
import (
|
|
"runtime"
|
|
"unsafe"
|
|
)
|
|
|
|
type SysProcAttr struct {
|
|
Chroot string // Chroot.
|
|
Credential *Credential // Credential.
|
|
Ptrace bool // Enable tracing.
|
|
Setsid bool // Create session.
|
|
// Setpgid sets the process group ID of the child to Pgid,
|
|
// or, if Pgid == 0, to the new child's process ID.
|
|
Setpgid bool
|
|
// Setctty sets the controlling terminal of the child to
|
|
// file descriptor Ctty. Ctty must be a descriptor number
|
|
// in the child process: an index into ProcAttr.Files.
|
|
// This is only meaningful if Setsid is true.
|
|
Setctty bool
|
|
Noctty bool // Detach fd 0 from controlling terminal
|
|
Ctty int // Controlling TTY fd
|
|
// Foreground places the child process group in the foreground.
|
|
// This implies Setpgid. The Ctty field must be set to
|
|
// the descriptor of the controlling TTY.
|
|
// 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.
|
|
}
|
|
|
|
// Implemented in runtime package.
|
|
func runtime_BeforeFork()
|
|
func runtime_AfterFork()
|
|
func runtime_AfterForkInChild()
|
|
|
|
// Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.
|
|
// If a dup or exec fails, write the errno error to pipe.
|
|
// (Pipe is close-on-exec so if exec succeeds, it will be closed.)
|
|
// In the child, this function must not acquire any locks, because
|
|
// they might have been locked at the time of the fork. This means
|
|
// no rescheduling, no malloc calls, and no new stack segments.
|
|
// For the same reason compiler does not race instrument it.
|
|
// The calls to RawSyscall are okay because they are assembly
|
|
// functions that do not grow the stack.
|
|
//go:norace
|
|
func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
|
|
// Declare all variables at top in case any
|
|
// declarations require heap allocation (e.g., err1).
|
|
var (
|
|
r1 Pid_t
|
|
err1 Errno
|
|
nextfd int
|
|
i int
|
|
)
|
|
|
|
// 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.
|
|
fd := make([]int, len(attr.Files))
|
|
nextfd = len(attr.Files)
|
|
for i, ufd := range attr.Files {
|
|
if nextfd < int(ufd) {
|
|
nextfd = int(ufd)
|
|
}
|
|
fd[i] = int(ufd)
|
|
}
|
|
nextfd++
|
|
|
|
// About to call fork.
|
|
// No more allocation or calls of non-assembly functions.
|
|
runtime_BeforeFork()
|
|
r1, err1 = raw_fork()
|
|
if err1 != 0 {
|
|
runtime_AfterFork()
|
|
return 0, err1
|
|
}
|
|
|
|
if r1 != 0 {
|
|
// parent; return PID
|
|
runtime_AfterFork()
|
|
return int(r1), 0
|
|
}
|
|
|
|
// Fork succeeded, now in child.
|
|
|
|
// Enable tracing if requested.
|
|
if sys.Ptrace {
|
|
err1 = raw_ptrace(_PTRACE_TRACEME, 0, 0, 0)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// Session ID
|
|
if sys.Setsid {
|
|
err1 = raw_setsid()
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// Set process group
|
|
if sys.Setpgid || sys.Foreground {
|
|
// Place child in process group.
|
|
err1 = raw_setpgid(0, sys.Pgid)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
if sys.Foreground {
|
|
pgrp := Pid_t(sys.Pgid)
|
|
if pgrp == 0 {
|
|
pgrp = raw_getpid()
|
|
}
|
|
|
|
// Place process group in foreground.
|
|
_, err1 = raw_ioctl_ptr(sys.Ctty, TIOCSPGRP, unsafe.Pointer(&pgrp))
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// Restore the signal mask. We do this after TIOCSPGRP to avoid
|
|
// having the kernel send a SIGTTOU signal to the process group.
|
|
runtime_AfterForkInChild()
|
|
|
|
// Chroot
|
|
if chroot != nil {
|
|
err1 = raw_chroot(chroot)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// User and groups
|
|
if cred := sys.Credential; cred != nil {
|
|
ngroups := len(cred.Groups)
|
|
var groups unsafe.Pointer
|
|
if ngroups > 0 {
|
|
gids := make([]Gid_t, ngroups)
|
|
for i, v := range cred.Groups {
|
|
gids[i] = Gid_t(v)
|
|
}
|
|
groups = unsafe.Pointer(&gids[0])
|
|
}
|
|
if !cred.NoSetGroups {
|
|
err1 = raw_setgroups(ngroups, groups)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
err2 := Setgid(int(cred.Gid))
|
|
if err2 != nil {
|
|
err1 = err2.(Errno)
|
|
goto childerror
|
|
}
|
|
err2 = Setuid(int(cred.Uid))
|
|
if err2 != nil {
|
|
err1 = err2.(Errno)
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// Chdir
|
|
if dir != nil {
|
|
err1 = raw_chdir(dir)
|
|
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 {
|
|
switch runtime.GOOS {
|
|
case "netbsd":
|
|
err1 = raw_dup3(pipe, nextfd, O_CLOEXEC)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
default:
|
|
err1 = raw_dup2(pipe, nextfd)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
|
|
}
|
|
pipe = nextfd
|
|
nextfd++
|
|
}
|
|
for i = 0; i < len(fd); i++ {
|
|
if fd[i] >= 0 && fd[i] < int(i) {
|
|
if nextfd == pipe { // don't stomp on pipe
|
|
nextfd++
|
|
}
|
|
switch runtime.GOOS {
|
|
case "netbsd":
|
|
err1 = raw_dup3(fd[i], nextfd, O_CLOEXEC)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
default:
|
|
err1 = raw_dup2(fd[i], nextfd)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
|
|
}
|
|
fd[i] = nextfd
|
|
nextfd++
|
|
}
|
|
}
|
|
|
|
// Pass 2: dup fd[i] down onto i.
|
|
for i = 0; i < len(fd); i++ {
|
|
if fd[i] == -1 {
|
|
raw_close(i)
|
|
continue
|
|
}
|
|
if fd[i] == int(i) {
|
|
// dup2(i, i) won't clear close-on-exec flag on Linux,
|
|
// probably not elsewhere either.
|
|
_, err1 = raw_fcntl(fd[i], F_SETFD, 0)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
continue
|
|
}
|
|
// The new fd is created NOT close-on-exec,
|
|
// which is exactly what we want.
|
|
err1 = raw_dup2(fd[i], i)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// By convention, we don't close-on-exec the fds we are
|
|
// started with, so if len(fd) < 3, close 0, 1, 2 as needed.
|
|
// Programs that know they inherit fds >= 3 will need
|
|
// to set them close-on-exec.
|
|
for i = len(fd); i < 3; i++ {
|
|
raw_close(i)
|
|
}
|
|
|
|
// Detach fd 0 from tty
|
|
if sys.Noctty {
|
|
_, err1 = raw_ioctl(0, TIOCNOTTY, 0)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// Set the controlling TTY to Ctty
|
|
if sys.Setctty {
|
|
if TIOCSCTTY == 0 {
|
|
err1 = ENOSYS
|
|
goto childerror
|
|
}
|
|
_, err1 = raw_ioctl(sys.Ctty, TIOCSCTTY, 0)
|
|
if err1 != 0 {
|
|
goto childerror
|
|
}
|
|
}
|
|
|
|
// Time to exec.
|
|
err1 = raw_execve(argv0, &argv[0], &envv[0])
|
|
|
|
childerror:
|
|
// send error code on pipe
|
|
raw_write(pipe, (*byte)(unsafe.Pointer(&err1)), int(unsafe.Sizeof(err1)))
|
|
for {
|
|
raw_exit(253)
|
|
}
|
|
}
|