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restic/internal/backend/foreground_unix.go
greatroar 11fbaaae9a Sanitize environment before starting backend processes (rclone, ssh)
The restic security model includes full trust of the local machine, so
this should not fix any actual security problems, but it's better to be
safe than sorry.

Fixes #2192.
2020-11-02 16:41:23 +01:00

76 lines
1.4 KiB
Go

// +build !solaris
// +build !windows
package backend
import (
"os"
"os/exec"
"os/signal"
"syscall"
"unsafe"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
)
func tcsetpgrp(fd int, pid int) error {
_, _, errno := syscall.RawSyscall(syscall.SYS_IOCTL, uintptr(fd),
uintptr(syscall.TIOCSPGRP), uintptr(unsafe.Pointer(&pid)))
if errno == 0 {
return nil
}
return errno
}
func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
// open the TTY, we need the file descriptor
tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)
if err != nil {
debug.Log("unable to open tty: %v", err)
bg = func() error {
return nil
}
return bg, cmd.Start()
}
signal.Ignore(syscall.SIGTTIN)
signal.Ignore(syscall.SIGTTOU)
// run the command in its own process group
cmd.SysProcAttr = &syscall.SysProcAttr{
Setpgid: true,
}
// start the process
err = cmd.Start()
if err != nil {
_ = tty.Close()
return nil, errors.Wrap(err, "cmd.Start")
}
// move the command's process group into the foreground
prev := syscall.Getpgrp()
err = tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
if err != nil {
_ = tty.Close()
return nil, err
}
bg = func() error {
signal.Reset(syscall.SIGTTIN)
signal.Reset(syscall.SIGTTOU)
// reset the foreground process group
err = tcsetpgrp(int(tty.Fd()), prev)
if err != nil {
_ = tty.Close()
return err
}
return tty.Close()
}
return bg, nil
}