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Merge pull request #9490 from btw616:erofs-avoid-escapes

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PiperOrigin-RevId: 576935895
This commit is contained in:
gVisor bot
2023-10-26 11:30:07 -07:00
parent 3574bdd750 56ce124756
commit 6df16e790c
4 changed files with 137 additions and 43 deletions
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pkg/erofs/BUILD
+4 -2
View File
@@ -7,7 +7,10 @@ package(
go_library(
name = "erofs",
srcs = ["erofs.go"],
srcs = [
"erofs.go",
"erofs_unsafe.go",
],
marshal = True,
visibility = ["//visibility:public"],
deps = [
@@ -17,7 +20,6 @@ go_library(
"//pkg/hostarch",
"//pkg/log",
"//pkg/marshal",
"//pkg/marshal/primitive",
"//pkg/safemem",
"@org_golang_x_sys//unix:go_default_library",
],
pkg/erofs/erofs.go
+104 -33
View File
@@ -35,7 +35,6 @@ import (
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/marshal"
"gvisor.dev/gvisor/pkg/marshal/primitive"
"gvisor.dev/gvisor/pkg/safemem"
)
@@ -92,6 +91,14 @@ const (
FeatureIncompatSupported = 0x0
)
// Sizes of on-disk structures in bytes.
const (
SuperBlockSize = 128
InodeCompactSize = 32
InodeExtendedSize = 64
DirentSize = 12
)
// SuperBlock represents on-disk super block.
//
// +marshal
@@ -176,16 +183,20 @@ type InodeExtended struct {
// Dirent represents on-disk directory entry.
//
// This struct is misaligned according to go_marshal, as it is only 12 bytes in size. The
// last field needs to be marked unaligned so the struct is marked unpacked and the
// generated methods behave correctly.
//
// +marshal
type Dirent struct {
Nid uint64
NidLow uint32
NidHigh uint32
NameOff uint16
FileType uint8
Reserved uint8 `marshal:"unaligned"`
Reserved uint8
}
// Nid returns the inode number of the inode referenced by this dirent.
func (d *Dirent) Nid() uint64 {
// EROFS on-disk structures are always in little endian.
// TODO: This implementation does not support big endian yet.
return (uint64(d.NidHigh) << 32) | uint64(d.NidLow)
}
// Image represents an open EROFS image.
@@ -251,7 +262,8 @@ func (i *Image) RootNid() uint64 {
// initSuperBlock initializes the super block of this image.
func (i *Image) initSuperBlock() error {
if err := i.UnmarshalAt(&i.sb, SuperBlockOffset); err != nil {
// i.sb is used in the hot path. Let's save a copy of it.
if err := i.unmarshalAt(&i.sb, SuperBlockOffset); err != nil {
return fmt.Errorf("image size is too small")
}
@@ -303,19 +315,79 @@ func (i *Image) FD() int {
return int(i.src.Fd())
}
// BytesAt returns the bytes at [off, off+n) of the image.
func (i *Image) BytesAt(off, n uint64) ([]byte, error) {
// checkRange checks whether the range [off, off+n) is valid.
func (i *Image) checkRange(off, n uint64) bool {
size := uint64(len(i.bytes))
end := off + n
if off >= size || off > end || end > size {
log.Warningf("Invalid range (off: 0x%x, n: 0x%x) for image (size: 0x%x)", off, n, size)
return nil, linuxerr.EFAULT
}
return i.bytes[off:end], nil
return off < size && off <= end && end <= size
}
// UnmarshalAt deserializes data from the bytes at [off, off+n) of the image.
func (i *Image) UnmarshalAt(data marshal.Marshallable, off uint64) error {
// BytesAt returns the bytes at [off, off+n) of the image.
func (i *Image) BytesAt(off, n uint64) ([]byte, error) {
if ok := i.checkRange(off, n); !ok {
log.Warningf("Invalid byte range (off: 0x%x, n: 0x%x) for image (size: 0x%x)", off, n, len(i.bytes))
return nil, linuxerr.EFAULT
}
return i.bytes[off : off+n], nil
}
// checkInodeAlignment checks whether off matches inode's alignment requirement.
func checkInodeAlignment(off uint64) bool {
// Each valid inode should be aligned with an inode slot, which is
// a fixed value (32 bytes).
return off&((1<<InodeSlotBits)-1) == 0
}
// inodeFormatAt returns the format of the inode at off in the memory backed by image.
func (i *Image) inodeFormatAt(off uint64) (uint16, error) {
if ok := checkInodeAlignment(off); !ok {
return 0, linuxerr.EFAULT
}
if ok := i.checkRange(off, 2); !ok {
return 0, linuxerr.EFAULT
}
return *(*uint16)(i.pointerAt(off)), nil
}
// inodeCompactAt returns the pointer to the compact inode at off in the memory
// backed by image.
func (i *Image) inodeCompactAt(off uint64) (*InodeCompact, error) {
if ok := checkInodeAlignment(off); !ok {
return nil, linuxerr.EFAULT
}
if ok := i.checkRange(off, InodeCompactSize); !ok {
return nil, linuxerr.EFAULT
}
return (*InodeCompact)(i.pointerAt(off)), nil
}
// inodeExtendedAt returns the pointer to the extended inode at off in the
// memory backed by image.
func (i *Image) inodeExtendedAt(off uint64) (*InodeExtended, error) {
if ok := checkInodeAlignment(off); !ok {
return nil, linuxerr.EFAULT
}
if ok := i.checkRange(off, InodeExtendedSize); !ok {
return nil, linuxerr.EFAULT
}
return (*InodeExtended)(i.pointerAt(off)), nil
}
// direntAt returns the pointer to the dirent at off in the memory backed
// by image.
func (i *Image) direntAt(off uint64) (*Dirent, error) {
// Each valid dirent should be aligned to 4 bytes.
if off&3 != 0 {
return nil, linuxerr.EFAULT
}
if ok := i.checkRange(off, DirentSize); !ok {
return nil, linuxerr.EFAULT
}
return (*Dirent)(i.pointerAt(off)), nil
}
// unmarshalAt deserializes data from the bytes at [off, off+n) of the image.
func (i *Image) unmarshalAt(data marshal.Marshallable, off uint64) error {
bytes, err := i.BytesAt(off, uint64(data.SizeBytes()))
if err != nil {
log.Warningf("Failed to deserialize %T from 0x%x.", data, off)
@@ -326,9 +398,6 @@ func (i *Image) UnmarshalAt(data marshal.Marshallable, off uint64) error {
}
// Inode returns the inode identified by nid.
//
// TODO: Ideally, we should avoid escaping objects to heap when constructing
// objects from the image.
func (i *Image) Inode(nid uint64) (Inode, error) {
inode := Inode{
image: i,
@@ -336,8 +405,10 @@ func (i *Image) Inode(nid uint64) (Inode, error) {
}
off := i.sb.NidToOffset(nid)
if err := i.UnmarshalAt(&inode.format, off); err != nil {
if format, err := i.inodeFormatAt(off); err != nil {
return Inode{}, err
} else {
inode.format = format
}
var (
@@ -347,8 +418,8 @@ func (i *Image) Inode(nid uint64) (Inode, error) {
switch layout := inode.Layout(); layout {
case InodeLayoutCompact:
var ino InodeCompact
if err := i.UnmarshalAt(&ino, off); err != nil {
ino, err := i.inodeCompactAt(off)
if err != nil {
return Inode{}, err
}
@@ -369,8 +440,8 @@ func (i *Image) Inode(nid uint64) (Inode, error) {
inode.mtimeNsec = i.sb.BuildTimeNsec
case InodeLayoutExtended:
var ino InodeExtended
if err := i.UnmarshalAt(&ino, off); err != nil {
ino, err := i.inodeExtendedAt(off)
if err != nil {
return Inode{}, err
}
@@ -435,7 +506,7 @@ type Inode struct {
idataOff uint64
// format is the format of this inode.
format primitive.Uint16
format uint16
// Metadata.
mode uint16
@@ -635,10 +706,10 @@ func (i *Inode) IterDirents(cb func(name string, typ uint8, nid uint64) error) e
// Iterate all the blocks which contain dirents.
for blocks > 0 {
// Unmarshal the first dirent in the current block.
// Get the first dirent in the current block.
direntOff := start
d := &Dirent{}
if err := i.image.UnmarshalAt(d, direntOff); err != nil {
d, err := i.image.direntAt(direntOff)
if err != nil {
return err
}
// Apart from the offset of the first filename, nameOff0 also indicates
@@ -663,9 +734,8 @@ func (i *Inode) IterDirents(cb func(name string, typ uint8, nid uint64) error) e
next = nil
nameLen = maxSize - uint32(d.NameOff)
} else {
// Unmarshal the next adjacent dirent.
next = &Dirent{}
if err := i.image.UnmarshalAt(next, direntOff); err != nil {
// Get the next adjacent dirent.
if next, err = i.image.direntAt(direntOff); err != nil {
return err
}
nameLen = uint32(next.NameOff - d.NameOff)
@@ -685,10 +755,11 @@ func (i *Inode) IterDirents(cb func(name string, typ uint8, nid uint64) error) e
return linuxerr.EUCLEAN
}
name := string(buf[:nameLen])
if err := cb(name, d.FileType, d.Nid); err != nil {
if err := cb(name, d.FileType, d.Nid()); err != nil {
return err
}
// Go on to process the next adjacent dirent.
d = next
}
pkg/erofs/erofs_test.go
+8 -8
View File
@@ -19,19 +19,19 @@ import (
)
func TestOnDiskStructureSizes(t *testing.T) {
if sb := new(SuperBlock); sb.SizeBytes() != 128 {
t.Errorf("wrong super block size: want 128, got %d", sb.SizeBytes())
if sb := new(SuperBlock); sb.SizeBytes() != SuperBlockSize {
t.Errorf("wrong super block size: want %d, got %d", SuperBlockSize, sb.SizeBytes())
}
if i := new(InodeCompact); i.SizeBytes() != 32 {
t.Errorf("wrong compact inode size: want 32, got %d", i.SizeBytes())
if i := new(InodeCompact); i.SizeBytes() != InodeCompactSize {
t.Errorf("wrong compact inode size: want %d, got %d", InodeCompactSize, i.SizeBytes())
}
if i := new(InodeExtended); i.SizeBytes() != 64 {
t.Errorf("wrong extended inode size: want 64, got %d", i.SizeBytes())
if i := new(InodeExtended); i.SizeBytes() != InodeExtendedSize {
t.Errorf("wrong extended inode size: want %d, got %d", InodeExtendedSize, i.SizeBytes())
}
if d := new(Dirent); d.SizeBytes() != 12 {
t.Errorf("wrong dirent size: want 12, got %d", d.SizeBytes())
if d := new(Dirent); d.SizeBytes() != DirentSize {
t.Errorf("wrong dirent size: want %d, got %d", DirentSize, d.SizeBytes())
}
}
pkg/erofs/erofs_unsafe.go
+21
View File
@@ -0,0 +1,21 @@
// Copyright 2023 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 erofs
import "unsafe"
func (i *Image) pointerAt(off uint64) unsafe.Pointer {
return unsafe.Pointer(&i.bytes[off])
}