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// 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
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"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/vfs"
)
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(ctx); err != nil {
t.Fatalf("VFS init: %v", err)
}
// Register tmpfs just so that we can have a root filesystem that isn't
// devtmpfs.
vfsObj.MustRegisterFilesystemType("tmpfs", tmpfs.FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{
AllowUserMount: true,
})
vfsObj.MustRegisterFilesystemType("devtmpfs", &FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{
AllowUserMount: true,
})
// Create a test mount namespace with devtmpfs mounted at "/dev".
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)
}
root := mntns.Root()
root.IncRef()
devpop := vfs.PathOperation{
Root: root,
Start: root,
Path: fspath.Parse(devPath),
}
if err := vfsObj.MkdirAt(ctx, creds, &devpop, &vfs.MkdirOptions{
Mode: 0755,
}); 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 {
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(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.
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",
},
}
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)
}
}
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)
}
}
}
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)
}
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,
},
}
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)
}
}
}
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