sysinfo: use Prctl() from x/sys/unix

Use unix.Prctl() instead of manually reimplementing it using
unix.RawSyscall. Also use unix.SECCOMP_MODE_FILTER instead of locally
defining it.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

pkg/sysinfo/sysinfo_linux.go

@@ -12,11 +12,6 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-const (
-	// SeccompModeFilter refers to the syscall argument SECCOMP_MODE_FILTER.
-	SeccompModeFilter = uintptr(2)
-)
-
 func findCgroupMountpoints() (map[string]string, error) {
 	cgMounts, err := cgroups.GetCgroupMounts(false)
 	if err != nil {
@@ -60,9 +55,9 @@ func New(quiet bool) *SysInfo {
 	}
 
 	// Check if Seccomp is supported, via CONFIG_SECCOMP.
-	if _, _, err := unix.RawSyscall(unix.SYS_PRCTL, unix.PR_GET_SECCOMP, 0, 0); err != unix.EINVAL {
+	if err := unix.Prctl(unix.PR_GET_SECCOMP, 0, 0, 0, 0); err != unix.EINVAL {
 		// Make sure the kernel has CONFIG_SECCOMP_FILTER.
-		if _, _, err := unix.RawSyscall(unix.SYS_PRCTL, unix.PR_SET_SECCOMP, SeccompModeFilter, 0); err != unix.EINVAL {
+		if err := unix.Prctl(unix.PR_SET_SECCOMP, unix.SECCOMP_MODE_FILTER, 0, 0, 0); err != unix.EINVAL {
 			sysInfo.Seccomp = true
 		}
 	}

pkg/sysinfo/sysinfo_linux_test.go

@@ -5,10 +5,10 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"syscall"
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"golang.org/x/sys/unix"
 )
 
 func TestReadProcBool(t *testing.T) {
@@ -66,9 +66,9 @@ func TestNew(t *testing.T) {
 
 func checkSysInfo(t *testing.T, sysInfo *SysInfo) {
 	// Check if Seccomp is supported, via CONFIG_SECCOMP.then sysInfo.Seccomp must be TRUE , else FALSE
-	if _, _, err := syscall.RawSyscall(syscall.SYS_PRCTL, syscall.PR_GET_SECCOMP, 0, 0); err != syscall.EINVAL {
+	if err := unix.Prctl(unix.PR_GET_SECCOMP, 0, 0, 0, 0); err != unix.EINVAL {
 		// Make sure the kernel has CONFIG_SECCOMP_FILTER.
-		if _, _, err := syscall.RawSyscall(syscall.SYS_PRCTL, syscall.PR_SET_SECCOMP, SeccompModeFilter, 0); err != syscall.EINVAL {
+		if err := unix.Prctl(unix.PR_SET_SECCOMP, unix.SECCOMP_MODE_FILTER, 0, 0, 0); err != unix.EINVAL {
 			require.True(t, sysInfo.Seccomp)
 		}
 	} else {