[vfs2] Remove VFS1 usage in VDSO.

Removed VDSO dependency on VFS1.

Resolves #2921

PiperOrigin-RevId: 320122176

pkg/sentry/fsimpl/testutil/kernel.go

@@ -73,7 +73,7 @@ func Boot() (*kernel.Kernel, error) {
 	k.SetMemoryFile(mf)
 
 	// Pass k as the platform since it is savable, unlike the actual platform.
-	vdso, err := loader.PrepareVDSO(nil, k)
+	vdso, err := loader.PrepareVDSO(k)
 	if err != nil {
 		return nil, fmt.Errorf("creating vdso: %v", err)
 	}

pkg/sentry/loader/BUILD

@@ -30,9 +30,6 @@ go_library(
         "//pkg/rand",
         "//pkg/safemem",
         "//pkg/sentry/arch",
-        "//pkg/sentry/fs",
-        "//pkg/sentry/fs/anon",
-        "//pkg/sentry/fs/fsutil",
         "//pkg/sentry/fsbridge",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/limits",
@@ -45,6 +42,5 @@ go_library(
         "//pkg/syserr",
         "//pkg/syserror",
         "//pkg/usermem",
-        "//pkg/waiter",
     ],
 )

pkg/sentry/loader/elf.go

@@ -90,14 +90,23 @@ type elfInfo struct {
 	sharedObject bool
 }
 
+// fullReader interface extracts the ReadFull method from fsbridge.File so that
+// client code does not need to define an entire fsbridge.File when only read
+// functionality is needed.
+//
+// TODO(gvisor.dev/issue/1035): Once VFS2 ships, rewrite this to wrap
+// vfs.FileDescription's PRead/Read instead.
+type fullReader interface {
+	// ReadFull is the same as fsbridge.File.ReadFull.
+	ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error)
+}
+
 // parseHeader parse the ELF header, verifying that this is a supported ELF
 // file and returning the ELF program headers.
 //
 // This is similar to elf.NewFile, except that it is more strict about what it
 // accepts from the ELF, and it doesn't parse unnecessary parts of the file.
-//
-// ctx may be nil if f does not need it.
-func parseHeader(ctx context.Context, f fsbridge.File) (elfInfo, error) {
+func parseHeader(ctx context.Context, f fullReader) (elfInfo, error) {
 	// Check ident first; it will tell us the endianness of the rest of the
 	// structs.
 	var ident [elf.EI_NIDENT]byte

pkg/sentry/loader/loader.go

@@ -27,7 +27,6 @@ import (
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/rand"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fs"
 	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
@@ -80,22 +79,6 @@ type LoadArgs struct {
 	Features *cpuid.FeatureSet
 }
 
-// readFull behaves like io.ReadFull for an *fs.File.
-func readFull(ctx context.Context, f *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
-	var total int64
-	for dst.NumBytes() > 0 {
-		n, err := f.Preadv(ctx, dst, offset+total)
-		total += n
-		if err == io.EOF && total != 0 {
-			return total, io.ErrUnexpectedEOF
-		} else if err != nil {
-			return total, err
-		}
-		dst = dst.DropFirst64(n)
-	}
-	return total, nil
-}
-
 // openPath opens args.Filename and checks that it is valid for loading.
 //
 // openPath returns an *fs.Dirent and *fs.File for args.Filename, which is not

pkg/sentry/loader/vdso.go

@@ -26,18 +26,13 @@ import (
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fs"
-	"gvisor.dev/gvisor/pkg/sentry/fs/anon"
-	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/mm"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/uniqueid"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
-	"gvisor.dev/gvisor/pkg/waiter"
 )
 
 const vdsoPrelink = 0xffffffffff700000
@@ -55,52 +50,11 @@ func (f *fileContext) Value(key interface{}) interface{} {
 	}
 }
 
-// byteReader implements fs.FileOperations for reading from a []byte source.
-type byteReader struct {
-	fsutil.FileNoFsync              `state:"nosave"`
-	fsutil.FileNoIoctl              `state:"nosave"`
-	fsutil.FileNoMMap               `state:"nosave"`
-	fsutil.FileNoSplice             `state:"nosave"`
-	fsutil.FileNoopFlush            `state:"nosave"`
-	fsutil.FileNoopRelease          `state:"nosave"`
-	fsutil.FileNotDirReaddir        `state:"nosave"`
-	fsutil.FilePipeSeek             `state:"nosave"`
-	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
-	waiter.AlwaysReady              `state:"nosave"`
-
+type byteFullReader struct {
 	data []byte
 }
 
-var _ fs.FileOperations = (*byteReader)(nil)
-
-// newByteReaderFile creates a fake file to read data from.
-//
-// TODO(gvisor.dev/issue/2921): Convert to VFS2.
-func newByteReaderFile(ctx context.Context, data []byte) *fs.File {
-	// Create a fake inode.
-	inode := fs.NewInode(
-		ctx,
-		&fsutil.SimpleFileInode{},
-		fs.NewPseudoMountSource(ctx),
-		fs.StableAttr{
-			Type:      fs.Anonymous,
-			DeviceID:  anon.PseudoDevice.DeviceID(),
-			InodeID:   anon.PseudoDevice.NextIno(),
-			BlockSize: usermem.PageSize,
-		})
-
-	// Use the fake inode to create a fake dirent.
-	dirent := fs.NewTransientDirent(inode)
-	defer dirent.DecRef()
-
-	// Use the fake dirent to make a fake file.
-	flags := fs.FileFlags{Read: true, Pread: true}
-	return fs.NewFile(&fileContext{Context: context.Background()}, dirent, flags, &byteReader{
-		data: data,
-	})
-}
-
-func (b *byteReader) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
+func (b *byteFullReader) ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
 	if offset < 0 {
 		return 0, syserror.EINVAL
 	}
@@ -111,10 +65,6 @@ func (b *byteReader) Read(ctx context.Context, file *fs.File, dst usermem.IOSequ
 	return int64(n), err
 }
 
-func (b *byteReader) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
-	panic("Write not supported")
-}
-
 // validateVDSO checks that the VDSO can be loaded by loadVDSO.
 //
 // VDSOs are special (see below). Since we are going to map the VDSO directly
@@ -130,7 +80,7 @@ func (b *byteReader) Write(ctx context.Context, file *fs.File, src usermem.IOSeq
 // * PT_LOAD segments don't extend beyond the end of the file.
 //
 // ctx may be nil if f does not need it.
-func validateVDSO(ctx context.Context, f fsbridge.File, size uint64) (elfInfo, error) {
+func validateVDSO(ctx context.Context, f fullReader, size uint64) (elfInfo, error) {
 	info, err := parseHeader(ctx, f)
 	if err != nil {
 		log.Infof("Unable to parse VDSO header: %v", err)
@@ -248,13 +198,12 @@ func getSymbolValueFromVDSO(symbol string) (uint64, error) {
 
 // PrepareVDSO validates the system VDSO and returns a VDSO, containing the
 // param page for updating by the kernel.
-func PrepareVDSO(ctx context.Context, mfp pgalloc.MemoryFileProvider) (*VDSO, error) {
-	vdsoFile := fsbridge.NewFSFile(newByteReaderFile(ctx, vdsoBin))
+func PrepareVDSO(mfp pgalloc.MemoryFileProvider) (*VDSO, error) {
+	vdsoFile := &byteFullReader{data: vdsoBin}
 
 	// First make sure the VDSO is valid. vdsoFile does not use ctx, so a
 	// nil context can be passed.
 	info, err := validateVDSO(nil, vdsoFile, uint64(len(vdsoBin)))
-	vdsoFile.DecRef()
 	if err != nil {
 		return nil, err
 	}

runsc/boot/loader.go

@@ -227,9 +227,7 @@ func New(args Args) (*Loader, error) {
 	// Create VDSO.
 	//
 	// Pass k as the platform since it is savable, unlike the actual platform.
-	//
-	// FIXME(b/109889800): Use non-nil context.
-	vdso, err := loader.PrepareVDSO(nil, k)
+	vdso, err := loader.PrepareVDSO(k)
 	if err != nil {
 		return nil, fmt.Errorf("creating vdso: %v", err)
 	}