From 2c422b7f21b3503e9b1ab52bdf8f0de7fcf4b8ce Mon Sep 17 00:00:00 2001 From: Nicolas Lacasse Date: Fri, 21 Aug 2020 12:08:25 -0700 Subject: Fix parent directory creation in CreateDeviceFile. It was not properly creating recursive directories. Added tests for this case. Updates #1196 PiperOrigin-RevId: 327850811 --- pkg/sentry/fsimpl/devtmpfs/BUILD | 1 + pkg/sentry/fsimpl/devtmpfs/devtmpfs.go | 13 +- pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go | 189 ++++++++++++++++++++++------ 3 files changed, 155 insertions(+), 48 deletions(-) (limited to 'pkg/sentry/fsimpl/devtmpfs') diff --git a/pkg/sentry/fsimpl/devtmpfs/BUILD b/pkg/sentry/fsimpl/devtmpfs/BUILD index aa0c2ad8c..01bbee5ad 100644 --- a/pkg/sentry/fsimpl/devtmpfs/BUILD +++ b/pkg/sentry/fsimpl/devtmpfs/BUILD @@ -24,6 +24,7 @@ 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 2ed5fa8a9..52f44f66d 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" @@ -150,13 +151,11 @@ func (a *Accessor) CreateDeviceFile(ctx context.Context, pathname string, kind v // Create any parent directories. See // devtmpfs.c:handle_create()=>path_create(). - for it := fspath.Parse(pathname).Begin; it.NextOk(); it = it.Next() { - pop := a.pathOperationAt(it.String()) - if err := a.vfsObj.MkdirAt(actx, a.creds, pop, &vfs.MkdirOptions{ - Mode: 0755, - }); err != nil { - return fmt.Errorf("failed to create directory %q: %v", it.String(), err) - } + 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 diff --git a/pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go b/pkg/sentry/fsimpl/devtmpfs/devtmpfs_test.go index 747867cca..6b56c5e71 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" @@ -25,10 +27,13 @@ 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(ctx); err != nil { t.Fatalf("VFS init: %v", err) @@ -43,14 +48,11 @@ 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{}) if err != nil { t.Fatalf("failed to create tmpfs root mount: %v", err) } - defer mntns.DecRef(ctx) root := mntns.Root() - defer root.DecRef(ctx) devpop := vfs.PathOperation{ Root: root, Start: root, @@ -65,6 +67,16 @@ func TestDevtmpfs(t *testing.T) { 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) @@ -75,48 +87,143 @@ func TestDevtmpfs(t *testing.T) { 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) + } } } -- cgit v1.2.3