Function SchedSetaffinity

pkg/sentry/syscalls/linux/sys_thread.go:507–540

SchedSetaffinity implements linux syscall sched_setaffinity(2).

(t *kernel.Task, sysno uintptr, args arch.SyscallArguments)

// SchedSetaffinity implements linux syscall sched_setaffinity(2).
func SchedSetaffinity(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
	tid := args[0].Int()
	size := args[1].SizeT()
	maskAddr := args[2].Pointer()

	var task *kernel.Task
	if tid == 0 {
		task = t
	} else {
		task = t.PIDNamespace().TaskWithID(kernel.ThreadID(tid))
		if task == nil {
			return 0, nil, linuxerr.ESRCH
		}
		// Linux requires the caller's EUID to match the target's
		// real or effective UID, or CAP_SYS_NICE in the target's user
		// namespace. See kernel/sched/syscalls.c:sched_setaffinity().
		creds := t.Credentials()
		tcreds := task.Credentials()
		if creds.EffectiveKUID != tcreds.EffectiveKUID &&
			creds.EffectiveKUID != tcreds.RealKUID &&
			!creds.HasCapabilityIn(linux.CAP_SYS_NICE, tcreds.UserNamespace) {
			return 0, nil, linuxerr.EPERM
		}
	}

	mask := sched.NewCPUSet(t.Kernel().ApplicationCores())
	if size > mask.Size() {
		size = mask.Size()
	}
	if _, err := t.CopyInBytes(maskAddr, mask[:size]); err != nil {
		return 0, nil, err
	}
	return 0, nil, task.SetCPUMask(mask)
}

// SchedGetaffinity implements linux syscall sched_getaffinity(2).
func SchedGetaffinity(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {