kvm: check that safecopy is handled correctly in the guest ring0

Signed-off-by: Andrei Vagin <avagin@google.com>

2 files changed, 108 insertions, 0 deletions

diff --git a/pkg/sentry/platform/kvm/BUILD b/pkg/sentry/platform/kvm/BUILD
index 1f5b88a64..9aba92e91 100644
--- a/pkg/sentry/platform/kvm/BUILD
+++ b/pkg/sentry/platform/kvm/BUILD
@@ -82,6 +82,7 @@ go_test(
         "kvm_amd64_test.go",
         "kvm_amd64_test.s",
         "kvm_arm64_test.go",
+        "kvm_safecopy_test.go",
         "kvm_test.go",
         "virtual_map_test.go",
     ],
@@ -94,8 +95,10 @@ go_test(
     deps = [
         "//pkg/abi/linux",
         "//pkg/hostarch",
+        "//pkg/memutil",
         "//pkg/ring0",
         "//pkg/ring0/pagetables",
+        "//pkg/safecopy",
         "//pkg/sentry/arch",
         "//pkg/sentry/arch/fpu",
         "//pkg/sentry/platform",
diff --git a/pkg/sentry/platform/kvm/kvm_safecopy_test.go b/pkg/sentry/platform/kvm/kvm_safecopy_test.go
new file mode 100644
index 000000000..cbfc61919
--- /dev/null
+++ b/pkg/sentry/platform/kvm/kvm_safecopy_test.go
@@ -0,0 +1,105 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// FIXME(gvisor.dev/issue//6629): These tests don't pass on ARM64.
+//
+//go:build amd64
+// +build amd64
+
+package kvm
+
+import (
+	"fmt"
+	"os"
+	"testing"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/hostarch"
+	"gvisor.dev/gvisor/pkg/memutil"
+	"gvisor.dev/gvisor/pkg/safecopy"
+)
+
+func testSafecopy(t *testing.T, mapSize uintptr, fileSize uintptr, testFunc func(t *testing.T, c *vCPU, addr uintptr)) {
+	memfd, err := memutil.CreateMemFD(fmt.Sprintf("kvm_test_%d", os.Getpid()), 0)
+	if err != nil {
+		t.Errorf("error creating memfd: %v", err)
+	}
+
+	memfile := os.NewFile(uintptr(memfd), "kvm_test")
+	memfile.Truncate(int64(fileSize))
+	kvmTest(t, nil, func(c *vCPU) bool {
+		const n = 10
+		mappings := make([]uintptr, n)
+		defer func() {
+			for i := 0; i < n && mappings[i] != 0; i++ {
+				unix.RawSyscall(
+					unix.SYS_MUNMAP,
+					mappings[i], mapSize, 0)
+			}
+		}()
+		for i := 0; i < n; i++ {
+			addr, _, errno := unix.RawSyscall6(
+				unix.SYS_MMAP,
+				0,
+				mapSize,
+				unix.PROT_READ|unix.PROT_WRITE,
+				unix.MAP_SHARED|unix.MAP_FILE,
+				uintptr(memfile.Fd()),
+				0)
+			if errno != 0 {
+				t.Errorf("error mapping file: %v", errno)
+			}
+			mappings[i] = addr
+			testFunc(t, c, addr)
+		}
+		return false
+	})
+}
+
+func TestSafecopySigbus(t *testing.T) {
+	mapSize := uintptr(faultBlockSize)
+	fileSize := mapSize - hostarch.PageSize
+	buf := make([]byte, hostarch.PageSize)
+	testSafecopy(t, mapSize, fileSize, func(t *testing.T, c *vCPU, addr uintptr) {
+		want := safecopy.BusError{addr + fileSize}
+		bluepill(c)
+		_, err := safecopy.CopyIn(buf, unsafe.Pointer(addr+fileSize))
+		if err != want {
+			t.Errorf("expected error: got %v, want %v", err, want)
+		}
+	})
+}
+
+func TestSafecopy(t *testing.T) {
+	mapSize := uintptr(faultBlockSize)
+	fileSize := mapSize
+	testSafecopy(t, mapSize, fileSize, func(t *testing.T, c *vCPU, addr uintptr) {
+		want := uint32(0x12345678)
+		bluepill(c)
+		_, err := safecopy.SwapUint32(unsafe.Pointer(addr+fileSize-8), want)
+		if err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+		bluepill(c)
+		val, err := safecopy.LoadUint32(unsafe.Pointer(addr + fileSize - 8))
+		if err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+		if val != want {
+			t.Errorf("incorrect value: got %x, want %x", val, want)
+		}
+	})
+}
+