1 files changed, 172 insertions, 0 deletions
diff --git a/pkg/sentry/fs/gofer/inode_state.go b/pkg/sentry/fs/gofer/inode_state.go
new file mode 100644
index 000000000..ac22ee4b1
--- /dev/null
+++ b/pkg/sentry/fs/gofer/inode_state.go
@@ -0,0 +1,172 @@
+// Copyright 2018 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.
+
+package gofer
+
+import (
+	"errors"
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"gvisor.googlesource.com/gvisor/pkg/p9"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/device"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
+)
+
+// Some fs implementations may not support atime, ctime, or mtime in getattr.
+// The unstable() logic would try to use clock time for them. However, we do not
+// want to use such time during S/R as that would cause restore timestamp
+// checking failure. Hence a dummy stable-time clock is needed.
+//
+// Note that application-visible UnstableAttrs either come from CachingInodeOps
+// (in which case they are saved), or they are requested from the gofer on each
+// stat (for non-caching), so the dummy time only affects the modification
+// timestamp check.
+type dummyClock struct {
+	time.Clock
+}
+
+// Now returns a stable dummy time.
+func (d *dummyClock) Now() time.Time {
+	return time.Time{}
+}
+
+type dummyClockContext struct {
+	context.Context
+}
+
+// Value implements context.Context
+func (d *dummyClockContext) Value(key interface{}) interface{} {
+	switch key {
+	case time.CtxRealtimeClock:
+		return &dummyClock{}
+	default:
+		return d.Context.Value(key)
+	}
+}
+
+// beforeSave is invoked by stateify.
+func (i *inodeFileState) beforeSave() {
+	if _, ok := i.s.inodeMappings[i.sattr.InodeID]; !ok {
+		panic(fmt.Sprintf("failed to find path for inode number %d. Device %s contains %s", i.sattr.InodeID, i.s.connID, fs.InodeMappings(i.s.inodeMappings)))
+	}
+	if i.sattr.Type == fs.RegularFile {
+		uattr, err := i.unstableAttr(&dummyClockContext{context.Background()})
+		if err != nil {
+			panic(fs.ErrSaveRejection{fmt.Errorf("failed to get unstable atttribute of %s: %v", i.s.inodeMappings[i.sattr.InodeID], err)})
+		}
+		i.savedUAttr = &uattr
+	}
+}
+
+// saveLoading is invoked by stateify.
+func (i *inodeFileState) saveLoading() struct{} {
+	return struct{}{}
+}
+
+// splitAbsolutePath splits the path on slashes ignoring the leading slash.
+func splitAbsolutePath(path string) []string {
+	if len(path) == 0 {
+		panic("There is no path!")
+	}
+	if path != filepath.Clean(path) {
+		panic(fmt.Sprintf("path %q is not clean", path))
+	}
+	// This case is to return {} rather than {""}
+	if path == "/" {
+		return []string{}
+	}
+	if path[0] != '/' {
+		panic(fmt.Sprintf("path %q is not absolute", path))
+	}
+
+	s := strings.Split(path, "/")
+
+	// Since p is absolute, the first component of s
+	// is an empty string. We must remove that.
+	return s[1:]
+}
+
+// loadLoading is invoked by stateify.
+func (i *inodeFileState) loadLoading(_ struct{}) {
+	i.loading.Lock()
+}
+
+// afterLoad is invoked by stateify.
+func (i *inodeFileState) afterLoad() {
+	load := func() (err error) {
+		// See comment on i.loading().
+		defer func() {
+			if err == nil {
+				i.loading.Unlock()
+			}
+		}()
+
+		// Manually restore the p9.File.
+		name, ok := i.s.inodeMappings[i.sattr.InodeID]
+		if !ok {
+			// This should be impossible, see assertion in
+			// beforeSave.
+			return fmt.Errorf("failed to find path for inode number %d. Device %s contains %s", i.sattr.InodeID, i.s.connID, fs.InodeMappings(i.s.inodeMappings))
+		}
+		// TODO(b/38173783): Context is not plumbed to save/restore.
+		ctx := &dummyClockContext{context.Background()}
+
+		_, i.file, err = i.s.attach.walk(ctx, splitAbsolutePath(name))
+		if err != nil {
+			return fs.ErrCorruption{fmt.Errorf("failed to walk to %q: %v", name, err)}
+		}
+
+		// Remap the saved inode number into the gofer device using the
+		// actual device and actual inode that exists in our new
+		// environment.
+		qid, mask, attrs, err := i.file.getAttr(ctx, p9.AttrMaskAll())
+		if err != nil {
+			return fs.ErrCorruption{fmt.Errorf("failed to get file attributes of %s: %v", name, err)}
+		}
+		if !mask.RDev {
+			return fs.ErrCorruption{fmt.Errorf("file %s lacks device", name)}
+		}
+		i.key = device.MultiDeviceKey{
+			Device:          attrs.RDev,
+			SecondaryDevice: i.s.connID,
+			Inode:           qid.Path,
+		}
+		if !goferDevice.Load(i.key, i.sattr.InodeID) {
+			return fs.ErrCorruption{fmt.Errorf("gofer device %s -> %d conflict in gofer device mappings: %s", i.key, i.sattr.InodeID, goferDevice)}
+		}
+
+		if i.sattr.Type == fs.RegularFile {
+			env, ok := fs.CurrentRestoreEnvironment()
+			if !ok {
+				return errors.New("missing restore environment")
+			}
+			uattr := unstable(ctx, mask, attrs, i.s.mounter, i.s.client)
+			if env.ValidateFileSize && uattr.Size != i.savedUAttr.Size {
+				return fs.ErrCorruption{fmt.Errorf("file size has changed for %s: previously %d, now %d", i.s.inodeMappings[i.sattr.InodeID], i.savedUAttr.Size, uattr.Size)}
+			}
+			if env.ValidateFileTimestamp && uattr.ModificationTime != i.savedUAttr.ModificationTime {
+				return fs.ErrCorruption{fmt.Errorf("file modification time has changed for %s: previously %v, now %v", i.s.inodeMappings[i.sattr.InodeID], i.savedUAttr.ModificationTime, uattr.ModificationTime)}
+			}
+			i.savedUAttr = nil
+		}
+
+		return nil
+	}
+
+	fs.Async(fs.CatchError(load))
+}