Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 169 insertions, 0 deletions

diff --git a/pkg/sentry/fs/ashmem/device.go b/pkg/sentry/fs/ashmem/device.go
new file mode 100644
index 000000000..c5b51d4a7
--- /dev/null
+++ b/pkg/sentry/fs/ashmem/device.go
@@ -0,0 +1,169 @@
+// Copyright 2018 Google Inc.
+//
+// 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 ashmem implements Android ashmem module (Anonymus Shared Memory).
+package ashmem
+
+import (
+	"sync"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/syserror"
+)
+
+// Device implements fs.InodeOperations.
+type Device struct {
+	fsutil.DeprecatedFileOperations
+	fsutil.InodeNoExtendedAttributes
+	fsutil.InodeNotDirectory
+	fsutil.InodeNotRenameable
+	fsutil.InodeNotSocket
+	fsutil.InodeNotSymlink
+	fsutil.NoFsync
+	fsutil.NoMappable
+	fsutil.NoopWriteOut
+	fsutil.NotDirReaddir
+
+	mu       sync.Mutex `state:"nosave"`
+	unstable fs.UnstableAttr
+}
+
+// NewDevice creates and intializes a Device structure.
+func NewDevice(ctx context.Context, owner fs.FileOwner, fp fs.FilePermissions) *Device {
+	return &Device{
+		unstable: fs.WithCurrentTime(ctx, fs.UnstableAttr{
+			Owner: owner,
+			Perms: fp,
+			Links: 1,
+		}),
+	}
+}
+
+// Release implements fs.InodeOperations.Release.
+func (ad *Device) Release(context.Context) {}
+
+// GetFile implements fs.InodeOperations.GetFile.
+func (ad *Device) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	return fs.NewFile(ctx, d, flags, &Area{
+		ad:        ad,
+		tmpfsFile: nil,
+		perms:     usermem.AnyAccess,
+	}), nil
+}
+
+// UnstableAttr implements fs.InodeOperations.UnstableAttr.
+func (ad *Device) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
+	ad.mu.Lock()
+	defer ad.mu.Unlock()
+	return ad.unstable, nil
+}
+
+// Check implements fs.InodeOperations.Check.
+func (ad *Device) Check(ctx context.Context, inode *fs.Inode, p fs.PermMask) bool {
+	return fs.ContextCanAccessFile(ctx, inode, p)
+}
+
+// SetPermissions implements fs.InodeOperations.SetPermissions.
+func (ad *Device) SetPermissions(ctx context.Context, inode *fs.Inode, fp fs.FilePermissions) bool {
+	ad.mu.Lock()
+	defer ad.mu.Unlock()
+	ad.unstable.Perms = fp
+	ad.unstable.StatusChangeTime = time.NowFromContext(ctx)
+	return true
+}
+
+// SetOwner implements fs.InodeOperations.SetOwner.
+func (ad *Device) SetOwner(ctx context.Context, inode *fs.Inode, owner fs.FileOwner) error {
+	ad.mu.Lock()
+	defer ad.mu.Unlock()
+	if owner.UID.Ok() {
+		ad.unstable.Owner.UID = owner.UID
+	}
+	if owner.GID.Ok() {
+		ad.unstable.Owner.GID = owner.GID
+	}
+	return nil
+}
+
+// SetTimestamps implements fs.InodeOperations.SetTimestamps.
+func (ad *Device) SetTimestamps(ctx context.Context, inode *fs.Inode, ts fs.TimeSpec) error {
+	if ts.ATimeOmit && ts.MTimeOmit {
+		return nil
+	}
+
+	ad.mu.Lock()
+	defer ad.mu.Unlock()
+
+	now := time.NowFromContext(ctx)
+	if !ts.ATimeOmit {
+		if ts.ATimeSetSystemTime {
+			ad.unstable.AccessTime = now
+		} else {
+			ad.unstable.AccessTime = ts.ATime
+		}
+	}
+	if !ts.MTimeOmit {
+		if ts.MTimeSetSystemTime {
+			ad.unstable.ModificationTime = now
+		} else {
+			ad.unstable.ModificationTime = ts.MTime
+		}
+	}
+	ad.unstable.StatusChangeTime = now
+	return nil
+}
+
+// Truncate implements fs.InodeOperations.WriteOut.
+//
+// Ignored by ashmem.
+func (ad *Device) Truncate(ctx context.Context, inode *fs.Inode, size int64) error {
+	return nil
+}
+
+// AddLink implements fs.InodeOperations.AddLink.
+//
+// Ashmem doesn't support links, no-op.
+func (ad *Device) AddLink() {}
+
+// DropLink implements fs.InodeOperations.DropLink.
+//
+// Ashmem doesn't support links, no-op.
+func (ad *Device) DropLink() {}
+
+// NotifyStatusChange implements fs.InodeOperations.NotifyStatusChange.
+func (ad *Device) NotifyStatusChange(ctx context.Context) {
+	ad.mu.Lock()
+	defer ad.mu.Unlock()
+	now := time.NowFromContext(ctx)
+	ad.unstable.ModificationTime = now
+	ad.unstable.StatusChangeTime = now
+}
+
+// IsVirtual implements fs.InodeOperations.IsVirtual.
+//
+// Ashmem is virtual.
+func (ad *Device) IsVirtual() bool {
+	return true
+}
+
+// StatFS implements fs.InodeOperations.StatFS.
+//
+// Ashmem doesn't support querying for filesystem info.
+func (ad *Device) StatFS(context.Context) (fs.Info, error) {
+	return fs.Info{}, syserror.ENOSYS
+}