5 files changed, 274 insertions, 0 deletions
diff --git a/pkg/sentry/fs/sys/device.go b/pkg/sentry/fs/sys/device.go
new file mode 100644
index 000000000..128d3a9d9
--- /dev/null
+++ b/pkg/sentry/fs/sys/device.go
@@ -0,0 +1,20 @@
+// 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 sys
+
+import "gvisor.googlesource.com/gvisor/pkg/sentry/device"
+
+// sysfsDevice is the sysfs virtual device.
+var sysfsDevice = device.NewAnonDevice()
diff --git a/pkg/sentry/fs/sys/devices.go b/pkg/sentry/fs/sys/devices.go
new file mode 100644
index 000000000..54f35c6a0
--- /dev/null
+++ b/pkg/sentry/fs/sys/devices.go
@@ -0,0 +1,91 @@
+// 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 sys
+
+import (
+	"fmt"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"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"
+)
+
+// +stateify savable
+type cpunum struct {
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotAllocatable       `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeNotTruncatable       `state:"nosave"`
+	fsutil.InodeNotVirtual           `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
+	fsutil.InodeStaticFileGetter
+}
+
+var _ fs.InodeOperations = (*cpunum)(nil)
+
+func newPossible(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
+	var maxCore uint
+	k := kernel.KernelFromContext(ctx)
+	if k != nil {
+		maxCore = k.ApplicationCores() - 1
+	}
+	contents := []byte(fmt.Sprintf("0-%d\n", maxCore))
+
+	c := &cpunum{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, fs.RootOwner, fs.FilePermsFromMode(0444), linux.SYSFS_MAGIC),
+		InodeStaticFileGetter: fsutil.InodeStaticFileGetter{
+			Contents: contents,
+		},
+	}
+	return newFile(c, msrc)
+}
+
+func newCPU(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
+	m := map[string]*fs.Inode{
+		"online":   newPossible(ctx, msrc),
+		"possible": newPossible(ctx, msrc),
+		"present":  newPossible(ctx, msrc),
+	}
+
+	// Add directories for each of the cpus.
+	if k := kernel.KernelFromContext(ctx); k != nil {
+		for i := 0; uint(i) < k.ApplicationCores(); i++ {
+			m[fmt.Sprintf("cpu%d", i)] = newDir(ctx, msrc, nil)
+		}
+	}
+
+	return newDir(ctx, msrc, m)
+}
+
+func newSystemDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
+	return newDir(ctx, msrc, map[string]*fs.Inode{
+		"cpu": newCPU(ctx, msrc),
+	})
+}
+
+func newDevicesDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
+	return newDir(ctx, msrc, map[string]*fs.Inode{
+		"system": newSystemDir(ctx, msrc),
+	})
+}
diff --git a/pkg/sentry/fs/sys/fs.go b/pkg/sentry/fs/sys/fs.go
new file mode 100644
index 000000000..f0c2322e0
--- /dev/null
+++ b/pkg/sentry/fs/sys/fs.go
@@ -0,0 +1,65 @@
+// 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 sys
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+)
+
+// filesystem is a sysfs.
+//
+// +stateify savable
+type filesystem struct{}
+
+var _ fs.Filesystem = (*filesystem)(nil)
+
+func init() {
+	fs.RegisterFilesystem(&filesystem{})
+}
+
+// FilesystemName is the name underwhich the filesystem is registered.
+// Name matches fs/sysfs/mount.c:sysfs_fs_type.name.
+const FilesystemName = "sysfs"
+
+// Name is the name of the file system.
+func (*filesystem) Name() string {
+	return FilesystemName
+}
+
+// AllowUserMount allows users to mount(2) this file system.
+func (*filesystem) AllowUserMount() bool {
+	return true
+}
+
+// AllowUserList allows this filesystem to be listed in /proc/filesystems.
+func (*filesystem) AllowUserList() bool {
+	return true
+}
+
+// Flags returns that there is nothing special about this file system.
+//
+// In Linux, sysfs returns FS_USERNS_VISIBLE | FS_USERNS_MOUNT, see fs/sysfs/mount.c.
+func (*filesystem) Flags() fs.FilesystemFlags {
+	return 0
+}
+
+// Mount returns a sysfs root which can be positioned in the vfs.
+func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, _ interface{}) (*fs.Inode, error) {
+	// device is always ignored.
+	// sysfs ignores data, see fs/sysfs/mount.c:sysfs_mount.
+
+	return New(ctx, fs.NewNonCachingMountSource(f, flags)), nil
+}
diff --git a/pkg/sentry/fs/sys/sys.go b/pkg/sentry/fs/sys/sys.go
new file mode 100644
index 000000000..d20ef91fa
--- /dev/null
+++ b/pkg/sentry/fs/sys/sys.go
@@ -0,0 +1,64 @@
+// 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 sys implements a sysfs filesystem.
+package sys
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+)
+
+func newFile(node fs.InodeOperations, msrc *fs.MountSource) *fs.Inode {
+	sattr := fs.StableAttr{
+		DeviceID:  sysfsDevice.DeviceID(),
+		InodeID:   sysfsDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+		Type:      fs.SpecialFile,
+	}
+	return fs.NewInode(node, msrc, sattr)
+}
+
+func newDir(ctx context.Context, msrc *fs.MountSource, contents map[string]*fs.Inode) *fs.Inode {
+	d := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
+	return fs.NewInode(d, msrc, fs.StableAttr{
+		DeviceID:  sysfsDevice.DeviceID(),
+		InodeID:   sysfsDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+		Type:      fs.SpecialDirectory,
+	})
+}
+
+// New returns the root node of a partial simple sysfs.
+func New(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
+	return newDir(ctx, msrc, map[string]*fs.Inode{
+		// Add a basic set of top-level directories. In Linux, these
+		// are dynamically added depending on the KConfig. Here we just
+		// add the most common ones.
+		"block": newDir(ctx, msrc, nil),
+		"bus":   newDir(ctx, msrc, nil),
+		"class": newDir(ctx, msrc, map[string]*fs.Inode{
+			"power_supply": newDir(ctx, msrc, nil),
+		}),
+		"dev":      newDir(ctx, msrc, nil),
+		"devices":  newDevicesDir(ctx, msrc),
+		"firmware": newDir(ctx, msrc, nil),
+		"fs":       newDir(ctx, msrc, nil),
+		"kernel":   newDir(ctx, msrc, nil),
+		"module":   newDir(ctx, msrc, nil),
+		"power":    newDir(ctx, msrc, nil),
+	})
+}
diff --git a/pkg/sentry/fs/sys/sys_state_autogen.go b/pkg/sentry/fs/sys/sys_state_autogen.go
new file mode 100755
index 000000000..84779f991
--- /dev/null
+++ b/pkg/sentry/fs/sys/sys_state_autogen.go
@@ -0,0 +1,34 @@
+// automatically generated by stateify.
+
+package sys
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/state"
+)
+
+func (x *cpunum) beforeSave() {}
+func (x *cpunum) save(m state.Map) {
+	x.beforeSave()
+	m.Save("InodeSimpleAttributes", &x.InodeSimpleAttributes)
+	m.Save("InodeStaticFileGetter", &x.InodeStaticFileGetter)
+}
+
+func (x *cpunum) afterLoad() {}
+func (x *cpunum) load(m state.Map) {
+	m.Load("InodeSimpleAttributes", &x.InodeSimpleAttributes)
+	m.Load("InodeStaticFileGetter", &x.InodeStaticFileGetter)
+}
+
+func (x *filesystem) beforeSave() {}
+func (x *filesystem) save(m state.Map) {
+	x.beforeSave()
+}
+
+func (x *filesystem) afterLoad() {}
+func (x *filesystem) load(m state.Map) {
+}
+
+func init() {
+	state.Register("sys.cpunum", (*cpunum)(nil), state.Fns{Save: (*cpunum).save, Load: (*cpunum).load})
+	state.Register("sys.filesystem", (*filesystem)(nil), state.Fns{Save: (*filesystem).save, Load: (*filesystem).load})
+}