pkg/vminfo: move feature checking to host

Feature checking procedure is split into 2 phases:
1. syz-fuzzer invokes "syz-executor setup feature" for each feature one-by-one,
and checks if executor does not fail.
Executor can also return a special "this feature does not need custom setup",
this allows to not call setup of these features in each new VM.
2. pkg/vminfo runs a simple program with ipc.ExecOpts specific for a concrete feature,
e.g. for wifi injection it will try to run a program with wifi feature enabled,
if setup of the feature fails, executor should also exit with an error.
For coverage features we also additionally check that we actually got coverage.
Then pkg/vminfo combines results of these 2 checks into final result.

syz-execprog now also uses vminfo package and mimics the same checking procedure.

Update #1541

1 files changed, 0 insertions, 355 deletions

diff --git a/pkg/host/features_linux.go b/pkg/host/features_linux.go
deleted file mode 100644
index 393617e45..000000000
--- a/pkg/host/features_linux.go
+++ /dev/null
@@ -1,355 +0,0 @@
-// Copyright 2015 syzkaller project authors. All rights reserved.
-// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
-
-package host
-
-import (
-	"fmt"
-	"os"
-	"os/exec"
-	"regexp"
-	"runtime"
-	"runtime/debug"
-	"strconv"
-	"syscall"
-	"unsafe"
-
-	"github.com/google/syzkaller/pkg/osutil"
-	"github.com/google/syzkaller/prog"
-	"github.com/google/syzkaller/sys/linux"
-	"golang.org/x/sys/unix"
-)
-
-func init() {
-	checkFeature[FeatureCoverage] = checkCoverage
-	checkFeature[FeatureComparisons] = checkComparisons
-	checkFeature[FeatureExtraCoverage] = checkExtraCoverage
-	checkFeature[FeatureDelayKcovMmap] = checkDelayKcovMmap
-	checkFeature[FeatureSandboxSetuid] = unconditionallyEnabled
-	checkFeature[FeatureSandboxNamespace] = checkSandboxNamespace
-	checkFeature[FeatureSandboxAndroid] = checkSandboxAndroid
-	checkFeature[FeatureFault] = checkFault
-	checkFeature[FeatureLeak] = checkLeak
-	checkFeature[FeatureNetInjection] = checkNetInjection
-	checkFeature[FeatureNetDevices] = unconditionallyEnabled
-	checkFeature[FeatureKCSAN] = checkKCSAN
-	checkFeature[FeatureDevlinkPCI] = checkDevlinkPCI
-	checkFeature[FeatureNicVF] = checkNicVF
-	checkFeature[FeatureUSBEmulation] = checkUSBEmulation
-	checkFeature[FeatureVhciInjection] = checkVhciInjection
-	checkFeature[FeatureWifiEmulation] = checkWifiEmulation
-	checkFeature[Feature802154Emulation] = check802154Emulation
-	checkFeature[FeatureSwap] = checkSwap
-}
-
-func checkCoverage() string {
-	if reason := checkDebugFS(); reason != "" {
-		return reason
-	}
-	if !osutil.IsExist("/sys/kernel/debug/kcov") {
-		return "CONFIG_KCOV is not enabled"
-	}
-	if err := osutil.IsAccessible("/sys/kernel/debug/kcov"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkComparisons() (reason string) {
-	return checkCoverageFeature(FeatureComparisons)
-}
-
-func checkExtraCoverage() (reason string) {
-	return checkCoverageFeature(FeatureExtraCoverage)
-}
-
-func checkDelayKcovMmap() string {
-	// The kcov implementation in Linux (currently) does not adequately handle subsequent
-	// mmap invocations on the same descriptor. When that problem is fixed, we want
-	// syzkaller to differentiate between distributions as this allows to noticeably speed
-	// up fuzzing.
-	return checkCoverageFeature(FeatureDelayKcovMmap)
-}
-
-func kcovTestMmap(fd int, coverSize uintptr) (reason string) {
-	mem, err := syscall.Mmap(fd, 0, int(coverSize*unsafe.Sizeof(uintptr(0))),
-		syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED)
-	if err != nil {
-		return fmt.Sprintf("KCOV mmap failed: %v", err)
-	}
-	defer func() {
-		if err := syscall.Munmap(mem); err != nil {
-			reason = fmt.Sprintf("munmap failed: %v", err)
-		}
-	}()
-	// Now the tricky part - mmap may say it has succeeded, but the memory is
-	// in fact not allocated.
-	// We try to access it. If go does not panic, everything is fine.
-	prevValue := debug.SetPanicOnFault(true)
-	defer debug.SetPanicOnFault(prevValue)
-	defer func() {
-		if r := recover(); r != nil {
-			reason = "mmap returned an invalid pointer"
-		}
-	}()
-	mem[0] = 0
-	return ""
-}
-
-func checkCoverageFeature(feature int) (reason string) {
-	if reason = checkDebugFS(); reason != "" {
-		return reason
-	}
-	// TODO(dvyukov): this should run under target arch.
-	// E.g. KCOV ioctls were initially not supported on 386 (missing compat_ioctl),
-	// and a 386 executor won't be able to use them, but an amd64 fuzzer will be.
-	fd, err := syscall.Open("/sys/kernel/debug/kcov", syscall.O_RDWR, 0)
-	if err != nil {
-		return "CONFIG_KCOV is not enabled"
-	}
-	defer syscall.Close(fd)
-	// Trigger host target lazy initialization, it will fill linux.KCOV_INIT_TRACE.
-	// It's all wrong and needs to be refactored.
-	if _, err := prog.GetTarget(runtime.GOOS, runtime.GOARCH); err != nil {
-		return fmt.Sprintf("failed to get target: %v", err)
-	}
-	coverSize := uintptr(64 << 10)
-	_, _, errno := syscall.Syscall(
-		syscall.SYS_IOCTL, uintptr(fd), linux.KCOV_INIT_TRACE, coverSize)
-	if errno != 0 {
-		return fmt.Sprintf("ioctl(KCOV_INIT_TRACE) failed: %v", errno)
-	}
-	if reason = kcovTestMmap(fd, coverSize); reason != "" {
-		return reason
-	}
-	disableKcov := func() {
-		_, _, errno = syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), linux.KCOV_DISABLE, 0)
-		if errno != 0 {
-			reason = fmt.Sprintf("ioctl(KCOV_DISABLE) failed: %v", errno)
-		}
-	}
-	switch feature {
-	case FeatureComparisons:
-		_, _, errno = syscall.Syscall(syscall.SYS_IOCTL,
-			uintptr(fd), linux.KCOV_ENABLE, linux.KCOV_TRACE_CMP)
-		if errno != 0 {
-			if errno == 524 { // ENOTSUPP
-				return "CONFIG_KCOV_ENABLE_COMPARISONS is not enabled"
-			}
-			return fmt.Sprintf("ioctl(KCOV_TRACE_CMP) failed: %v", errno)
-		}
-		defer disableKcov()
-	case FeatureExtraCoverage:
-		arg := KcovRemoteArg{
-			TraceMode:    uint32(linux.KCOV_TRACE_PC),
-			AreaSize:     uint32(coverSize * unsafe.Sizeof(uintptr(0))),
-			NumHandles:   0,
-			CommonHandle: 0,
-		}
-		_, _, errno = syscall.Syscall(syscall.SYS_IOCTL,
-			uintptr(fd), linux.KCOV_REMOTE_ENABLE, uintptr(unsafe.Pointer(&arg)))
-		if errno != 0 {
-			if errno == 25 { // ENOTTY
-				return "extra coverage is not supported by the kernel"
-			}
-			return fmt.Sprintf("ioctl(KCOV_REMOTE_ENABLE) failed: %v", errno)
-		}
-		defer disableKcov()
-	case FeatureDelayKcovMmap:
-		if reason = kcovTestMmap(fd, coverSize); reason != "" {
-			return reason
-		}
-	default:
-		panic("unknown feature in checkCoverageFeature")
-	}
-	return ""
-}
-
-type KcovRemoteArg struct {
-	TraceMode    uint32
-	AreaSize     uint32
-	NumHandles   uint32
-	_            uint32
-	CommonHandle uint64
-	// Handles []uint64 goes here.
-}
-
-func checkFault() string {
-	if err := osutil.IsAccessible("/proc/self/make-it-fail"); err != nil {
-		return "CONFIG_FAULT_INJECTION is not enabled"
-	}
-	if err := osutil.IsAccessible("/proc/thread-self/fail-nth"); err != nil {
-		return "kernel does not have systematic fault injection support"
-	}
-	if reason := checkDebugFS(); reason != "" {
-		return reason
-	}
-	if err := osutil.IsAccessible("/sys/kernel/debug/failslab/ignore-gfp-wait"); err != nil {
-		return "CONFIG_FAULT_INJECTION_DEBUG_FS or CONFIG_FAILSLAB are not enabled"
-	}
-	return ""
-}
-
-func checkLeak() string {
-	if reason := checkDebugFS(); reason != "" {
-		return reason
-	}
-	fd, err := syscall.Open("/sys/kernel/debug/kmemleak", syscall.O_RDWR, 0)
-	if err != nil {
-		return "CONFIG_DEBUG_KMEMLEAK is not enabled"
-	}
-	defer syscall.Close(fd)
-	if _, err := syscall.Write(fd, []byte("scan=off")); err != nil {
-		if err == syscall.EBUSY {
-			return "KMEMLEAK disabled: increase CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE or unset CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF"
-		}
-		return fmt.Sprintf("/sys/kernel/debug/kmemleak write failed: %v", err)
-	}
-	return ""
-}
-
-func checkSandboxNamespace() string {
-	if err := osutil.IsAccessible("/proc/self/ns/user"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkSandboxAndroid() string {
-	if err := osutil.IsAccessible("/sys/fs/selinux/policy"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkNetInjection() string {
-	if err := osutil.IsAccessible("/dev/net/tun"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkUSBEmulation() string {
-	if err := osutil.IsAccessible("/dev/raw-gadget"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkVhciInjection() string {
-	if err := osutil.IsAccessible("/dev/vhci"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkDebugFS() string {
-	if err := osutil.IsAccessible("/sys/kernel/debug"); err != nil {
-		return "debugfs is not enabled or not mounted"
-	}
-	return ""
-}
-
-func checkKCSAN() string {
-	if err := osutil.IsAccessible("/sys/kernel/debug/kcsan"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkDevlinkPCI() string {
-	if err := osutil.IsAccessible("/sys/bus/pci/devices/0000:00:10.0/"); err != nil {
-		return "PCI device 0000:00:10.0 is not available"
-	}
-	if err := osutil.IsAccessible("/proc/self/ns/net"); err != nil {
-		// Initialize_devlink_pci in executor fails w/o this.
-		return "/proc/self/ns/net does not exist"
-	}
-	return ""
-}
-
-func checkNicVF() string {
-	if err := osutil.IsAccessible("/sys/bus/pci/devices/0000:00:11.0/"); err != nil {
-		return "PCI device 0000:00:11.0 is not available"
-	}
-	return ""
-}
-
-func checkWifiEmulation() string {
-	if err := osutil.IsAccessible("/sys/class/mac80211_hwsim/"); err != nil {
-		return err.Error()
-	}
-	// We use HWSIM_ATTR_PERM_ADDR which was added in 4.17.
-	return requireKernel(4, 17)
-}
-
-func check802154Emulation() string {
-	if err := osutil.IsAccessible("/sys/bus/platform/devices/mac802154_hwsim"); err != nil {
-		return err.Error()
-	}
-	return ""
-}
-
-func checkSwap() string {
-	if err := osutil.IsAccessible("/proc/swaps"); err != nil {
-		return err.Error()
-	}
-	if _, err := exec.LookPath("mkswap"); err != nil {
-		return "mkswap is not available"
-	}
-	// We use fallocate in syz-executor, so let's check if the filesystem supports it.
-	// /tmp might not always be the best choice for this
-	// (on some systems, a different filesystem might be used for /tmp).
-	dir, err := os.UserHomeDir()
-	if err != nil {
-		return fmt.Sprintf("failed to get home dir: %v", err)
-	}
-	f, err := os.CreateTemp(dir, "any-file")
-	if err != nil {
-		return fmt.Sprintf("failed to create temp file: %v", err)
-	}
-	defer os.Remove(f.Name())
-	err = syscall.Fallocate(int(f.Fd()), unix.FALLOC_FL_ZERO_RANGE, 0, 2048)
-	if err != nil {
-		return fmt.Sprintf("fallocate failed: %v", err)
-	}
-	return ""
-}
-
-func requireKernel(x, y int) string {
-	info := new(unix.Utsname)
-	if err := unix.Uname(info); err != nil {
-		return fmt.Sprintf("uname failed: %v", err)
-	}
-	ver := string(info.Release[:])
-	if ok, bad := matchKernelVersion(ver, x, y); bad {
-		return fmt.Sprintf("failed to parse kernel version (%v)", ver)
-	} else if !ok {
-		return fmt.Sprintf("kernel %v.%v required (have %v)", x, y, ver)
-	}
-	return ""
-}
-
-func matchKernelVersion(ver string, x, y int) (bool, bool) {
-	match := kernelVersionRe.FindStringSubmatch(ver)
-	if match == nil {
-		return false, true
-	}
-	major, err := strconv.Atoi(match[1])
-	if err != nil {
-		return false, true
-	}
-	if major <= 0 || major > 999 {
-		return false, true
-	}
-	minor, err := strconv.Atoi(match[2])
-	if err != nil {
-		return false, true
-	}
-	if minor <= 0 || minor > 999 {
-		return false, true
-	}
-	return major*1000+minor >= x*1000+y, false
-}
-
-var kernelVersionRe = regexp.MustCompile(`^([0-9]+)\.([0-9]+)`)