summaryrefslogtreecommitdiffhomepage
path: root/pkg/sentry/fsimpl/devtmpfs
diff options
context:
space:
mode:
Diffstat (limited to 'pkg/sentry/fsimpl/devtmpfs')
-rw-r--r--pkg/sentry/fsimpl/devtmpfs/BUILD6
-rw-r--r--pkg/sentry/fsimpl/devtmpfs/devtmpfs.go41
-rw-r--r--pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go198
-rw-r--r--pkg/sentry/fsimpl/devtmpfs/save_restore.go23
4 files changed, 215 insertions, 53 deletions
diff --git a/pkg/sentry/fsimpl/devtmpfs/BUILD b/pkg/sentry/fsimpl/devtmpfs/BUILD
index aa0c2ad8c..e49a04c1b 100644
--- a/pkg/sentry/fsimpl/devtmpfs/BUILD
+++ b/pkg/sentry/fsimpl/devtmpfs/BUILD
@@ -4,7 +4,10 @@ licenses(["notice"])
go_library(
name = "devtmpfs",
- srcs = ["devtmpfs.go"],
+ srcs = [
+ "devtmpfs.go",
+ "save_restore.go",
+ ],
visibility = ["//pkg/sentry:internal"],
deps = [
"//pkg/abi/linux",
@@ -24,6 +27,7 @@ go_test(
library = ":devtmpfs",
deps = [
"//pkg/abi/linux",
+ "//pkg/context",
"//pkg/fspath",
"//pkg/sentry/contexttest",
"//pkg/sentry/fsimpl/tmpfs",
diff --git a/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go b/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go
index 142ee53b0..e6fe0fc0d 100644
--- a/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go
+++ b/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go
@@ -18,6 +18,7 @@ package devtmpfs
import (
"fmt"
+ "path"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
@@ -32,8 +33,10 @@ import (
const Name = "devtmpfs"
// FilesystemType implements vfs.FilesystemType.
+//
+// +stateify savable
type FilesystemType struct {
- initOnce sync.Once
+ initOnce sync.Once `state:"nosave"` // FIXME(gvisor.dev/issue/1664): not yet supported.
initErr error
// fs is the tmpfs filesystem that backs all mounts of this FilesystemType.
@@ -68,6 +71,15 @@ func (fst *FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virtua
return fst.fs, fst.root, nil
}
+// Release implements vfs.FilesystemType.Release.
+func (fst *FilesystemType) Release(ctx context.Context) {
+ if fst.fs != nil {
+ // Release the original reference obtained when creating the filesystem.
+ fst.root.DecRef(ctx)
+ fst.fs.DecRef(ctx)
+ }
+}
+
// Accessor allows devices to create device special files in devtmpfs.
type Accessor struct {
vfsObj *vfs.VirtualFilesystem
@@ -79,22 +91,25 @@ type Accessor struct {
// NewAccessor returns an Accessor that supports creation of device special
// files in the devtmpfs instance registered with name fsTypeName in vfsObj.
func NewAccessor(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, fsTypeName string) (*Accessor, error) {
- mntns, err := vfsObj.NewMountNamespace(ctx, creds, "devtmpfs" /* source */, fsTypeName, &vfs.GetFilesystemOptions{})
+ mntns, err := vfsObj.NewMountNamespace(ctx, creds, "devtmpfs" /* source */, fsTypeName, &vfs.MountOptions{})
if err != nil {
return nil, err
}
+ // Pass a reference on root to the Accessor.
+ root := mntns.Root()
+ root.IncRef()
return &Accessor{
vfsObj: vfsObj,
mntns: mntns,
- root: mntns.Root(),
+ root: root,
creds: creds,
}, nil
}
// Release must be called when a is no longer in use.
-func (a *Accessor) Release() {
- a.root.DecRef()
- a.mntns.DecRef()
+func (a *Accessor) Release(ctx context.Context) {
+ a.root.DecRef(ctx)
+ a.mntns.DecRef(ctx)
}
// accessorContext implements context.Context by extending an existing
@@ -136,6 +151,8 @@ func (a *Accessor) pathOperationAt(pathname string) *vfs.PathOperation {
// CreateDeviceFile creates a device special file at the given pathname in the
// devtmpfs instance accessed by the Accessor.
func (a *Accessor) CreateDeviceFile(ctx context.Context, pathname string, kind vfs.DeviceKind, major, minor uint32, perms uint16) error {
+ actx := a.wrapContext(ctx)
+
mode := (linux.FileMode)(perms)
switch kind {
case vfs.BlockDevice:
@@ -145,12 +162,22 @@ func (a *Accessor) CreateDeviceFile(ctx context.Context, pathname string, kind v
default:
panic(fmt.Sprintf("invalid vfs.DeviceKind: %v", kind))
}
+
+ // Create any parent directories. See
+ // devtmpfs.c:handle_create()=>path_create().
+ parent := path.Dir(pathname)
+ if err := a.vfsObj.MkdirAllAt(ctx, parent, a.root, a.creds, &vfs.MkdirOptions{
+ Mode: 0755,
+ }); err != nil {
+ return fmt.Errorf("failed to create device parent directory %q: %v", parent, err)
+ }
+
// NOTE: Linux's devtmpfs refuses to automatically delete files it didn't
// create, which it recognizes by storing a pointer to the kdevtmpfs struct
// thread in struct inode::i_private. Accessor doesn't yet support deletion
// of files at all, and probably won't as long as we don't need to support
// kernel modules, so this is moot for now.
- return a.vfsObj.MknodAt(a.wrapContext(ctx), a.creds, a.pathOperationAt(pathname), &vfs.MknodOptions{
+ return a.vfsObj.MknodAt(actx, a.creds, a.pathOperationAt(pathname), &vfs.MknodOptions{
Mode: mode,
DevMajor: major,
DevMinor: minor,
diff --git a/pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go b/pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go
index b6d52c015..e058eda7a 100644
--- a/pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go
+++ b/pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go
@@ -15,9 +15,11 @@
package devtmpfs
import (
+ "path"
"testing"
"gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/sentry/contexttest"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs"
@@ -25,12 +27,15 @@ import (
"gvisor.dev/gvisor/pkg/sentry/vfs"
)
-func TestDevtmpfs(t *testing.T) {
+const devPath = "/dev"
+
+func setupDevtmpfs(t *testing.T) (context.Context, *auth.Credentials, *vfs.VirtualFilesystem, vfs.VirtualDentry, func()) {
+ t.Helper()
+
ctx := contexttest.Context(t)
creds := auth.CredentialsFromContext(ctx)
-
vfsObj := &vfs.VirtualFilesystem{}
- if err := vfsObj.Init(); err != nil {
+ if err := vfsObj.Init(ctx); err != nil {
t.Fatalf("VFS init: %v", err)
}
// Register tmpfs just so that we can have a root filesystem that isn't
@@ -43,14 +48,12 @@ func TestDevtmpfs(t *testing.T) {
})
// Create a test mount namespace with devtmpfs mounted at "/dev".
- const devPath = "/dev"
- mntns, err := vfsObj.NewMountNamespace(ctx, creds, "tmpfs" /* source */, "tmpfs" /* fsTypeName */, &vfs.GetFilesystemOptions{})
+ mntns, err := vfsObj.NewMountNamespace(ctx, creds, "tmpfs" /* source */, "tmpfs" /* fsTypeName */, &vfs.MountOptions{})
if err != nil {
t.Fatalf("failed to create tmpfs root mount: %v", err)
}
- defer mntns.DecRef()
root := mntns.Root()
- defer root.DecRef()
+ root.IncRef()
devpop := vfs.PathOperation{
Root: root,
Start: root,
@@ -61,62 +64,167 @@ func TestDevtmpfs(t *testing.T) {
}); err != nil {
t.Fatalf("failed to create mount point: %v", err)
}
- if err := vfsObj.MountAt(ctx, creds, "devtmpfs" /* source */, &devpop, "devtmpfs" /* fsTypeName */, &vfs.MountOptions{}); err != nil {
+ if _, err := vfsObj.MountAt(ctx, creds, "devtmpfs" /* source */, &devpop, "devtmpfs" /* fsTypeName */, &vfs.MountOptions{}); err != nil {
t.Fatalf("failed to mount devtmpfs: %v", err)
}
+ return ctx, creds, vfsObj, root, func() {
+ root.DecRef(ctx)
+ mntns.DecRef(ctx)
+ }
+}
+
+func TestUserspaceInit(t *testing.T) {
+ ctx, creds, vfsObj, root, cleanup := setupDevtmpfs(t)
+ defer cleanup()
+
a, err := NewAccessor(ctx, vfsObj, creds, "devtmpfs")
if err != nil {
t.Fatalf("failed to create devtmpfs.Accessor: %v", err)
}
- defer a.Release()
+ defer a.Release(ctx)
// Create "userspace-initialized" files using a devtmpfs.Accessor.
if err := a.UserspaceInit(ctx); err != nil {
t.Fatalf("failed to userspace-initialize devtmpfs: %v", err)
}
+
// Created files should be visible in the test mount namespace.
- abspath := devPath + "/fd"
- target, err := vfsObj.ReadlinkAt(ctx, creds, &vfs.PathOperation{
- Root: root,
- Start: root,
- Path: fspath.Parse(abspath),
- })
- if want := "/proc/self/fd"; err != nil || target != want {
- t.Fatalf("readlink(%q): got (%q, %v), wanted (%q, nil)", abspath, target, err, want)
+ links := []struct {
+ source string
+ target string
+ }{
+ {
+ source: "fd",
+ target: "/proc/self/fd",
+ },
+ {
+ source: "stdin",
+ target: "/proc/self/fd/0",
+ },
+ {
+ source: "stdout",
+ target: "/proc/self/fd/1",
+ },
+ {
+ source: "stderr",
+ target: "/proc/self/fd/2",
+ },
+ {
+ source: "ptmx",
+ target: "pts/ptmx",
+ },
}
- // Create a dummy device special file using a devtmpfs.Accessor.
- const (
- pathInDev = "dummy"
- kind = vfs.CharDevice
- major = 12
- minor = 34
- perms = 0600
- wantMode = linux.S_IFCHR | perms
- )
- if err := a.CreateDeviceFile(ctx, pathInDev, kind, major, minor, perms); err != nil {
- t.Fatalf("failed to create device file: %v", err)
+ for _, link := range links {
+ abspath := path.Join(devPath, link.source)
+ if gotTarget, err := vfsObj.ReadlinkAt(ctx, creds, &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(abspath),
+ }); err != nil || gotTarget != link.target {
+ t.Errorf("readlink(%q): got (%q, %v), wanted (%q, nil)", abspath, gotTarget, err, link.target)
+ }
}
- // The device special file should be visible in the test mount namespace.
- abspath = devPath + "/" + pathInDev
- stat, err := vfsObj.StatAt(ctx, creds, &vfs.PathOperation{
- Root: root,
- Start: root,
- Path: fspath.Parse(abspath),
- }, &vfs.StatOptions{
- Mask: linux.STATX_TYPE | linux.STATX_MODE,
- })
- if err != nil {
- t.Fatalf("failed to stat device file at %q: %v", abspath, err)
+
+ dirs := []string{"shm", "pts"}
+ for _, dir := range dirs {
+ abspath := path.Join(devPath, dir)
+ statx, err := vfsObj.StatAt(ctx, creds, &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(abspath),
+ }, &vfs.StatOptions{
+ Mask: linux.STATX_MODE,
+ })
+ if err != nil {
+ t.Errorf("stat(%q): got error %v ", abspath, err)
+ continue
+ }
+ if want := uint16(0755) | linux.S_IFDIR; statx.Mode != want {
+ t.Errorf("stat(%q): got mode %x, want %x", abspath, statx.Mode, want)
+ }
}
- if stat.Mode != wantMode {
- t.Errorf("device file mode: got %v, wanted %v", stat.Mode, wantMode)
+}
+
+func TestCreateDeviceFile(t *testing.T) {
+ ctx, creds, vfsObj, root, cleanup := setupDevtmpfs(t)
+ defer cleanup()
+
+ a, err := NewAccessor(ctx, vfsObj, creds, "devtmpfs")
+ if err != nil {
+ t.Fatalf("failed to create devtmpfs.Accessor: %v", err)
}
- if stat.RdevMajor != major {
- t.Errorf("major device number: got %v, wanted %v", stat.RdevMajor, major)
+ defer a.Release(ctx)
+
+ devFiles := []struct {
+ path string
+ kind vfs.DeviceKind
+ major uint32
+ minor uint32
+ perms uint16
+ }{
+ {
+ path: "dummy",
+ kind: vfs.CharDevice,
+ major: 12,
+ minor: 34,
+ perms: 0600,
+ },
+ {
+ path: "foo/bar",
+ kind: vfs.BlockDevice,
+ major: 13,
+ minor: 35,
+ perms: 0660,
+ },
+ {
+ path: "foo/baz",
+ kind: vfs.CharDevice,
+ major: 12,
+ minor: 40,
+ perms: 0666,
+ },
+ {
+ path: "a/b/c/d/e",
+ kind: vfs.BlockDevice,
+ major: 12,
+ minor: 34,
+ perms: 0600,
+ },
}
- if stat.RdevMinor != minor {
- t.Errorf("minor device number: got %v, wanted %v", stat.RdevMinor, minor)
+
+ for _, f := range devFiles {
+ if err := a.CreateDeviceFile(ctx, f.path, f.kind, f.major, f.minor, f.perms); err != nil {
+ t.Fatalf("failed to create device file: %v", err)
+ }
+ // The device special file should be visible in the test mount namespace.
+ abspath := path.Join(devPath, f.path)
+ stat, err := vfsObj.StatAt(ctx, creds, &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(abspath),
+ }, &vfs.StatOptions{
+ Mask: linux.STATX_TYPE | linux.STATX_MODE,
+ })
+ if err != nil {
+ t.Fatalf("failed to stat device file at %q: %v", abspath, err)
+ }
+ if stat.RdevMajor != f.major {
+ t.Errorf("major device number: got %v, wanted %v", stat.RdevMajor, f.major)
+ }
+ if stat.RdevMinor != f.minor {
+ t.Errorf("minor device number: got %v, wanted %v", stat.RdevMinor, f.minor)
+ }
+ wantMode := f.perms
+ switch f.kind {
+ case vfs.CharDevice:
+ wantMode |= linux.S_IFCHR
+ case vfs.BlockDevice:
+ wantMode |= linux.S_IFBLK
+ }
+ if stat.Mode != wantMode {
+ t.Errorf("device file mode: got %v, wanted %v", stat.Mode, wantMode)
+ }
}
}
diff --git a/pkg/sentry/fsimpl/devtmpfs/save_restore.go b/pkg/sentry/fsimpl/devtmpfs/save_restore.go
new file mode 100644
index 000000000..28832d850
--- /dev/null
+++ b/pkg/sentry/fsimpl/devtmpfs/save_restore.go
@@ -0,0 +1,23 @@
+// Copyright 2020 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 devtmpfs
+
+// afterLoad is invoked by stateify.
+func (fst *FilesystemType) afterLoad() {
+ if fst.fs != nil {
+ // Ensure that we don't create another filesystem.
+ fst.initOnce.Do(func() {})
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-04-06 01:09:19 +0000