/
reader.go
468 lines (429 loc) · 10.8 KB
/
reader.go
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//
// Copyright (c) 2015-2022 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
package estream
import (
"bytes"
"crypto/rand"
"crypto/rsa"
"crypto/sha512"
"crypto/x509"
"encoding/hex"
"errors"
"fmt"
"io"
"runtime"
"github.com/cespare/xxhash/v2"
"github.com/secure-io/sio-go"
"github.com/tinylib/msgp/msgp"
)
type Reader struct {
mr *msgp.Reader
majorV uint8
minorV uint8
err error
inStream bool
key *[32]byte
private *rsa.PrivateKey
privateFn func(key *rsa.PublicKey) *rsa.PrivateKey
skipEncrypted bool
returnNonDec bool
}
// ErrNoKey is returned when a stream cannot be decrypted.
// The Skip function on the stream can be called to skip to the next.
var ErrNoKey = errors.New("no valid private key found")
// NewReader will return a Reader that will split streams.
func NewReader(r io.Reader) (*Reader, error) {
var ver [2]byte
if _, err := io.ReadFull(r, ver[:]); err != nil {
return nil, err
}
switch ver[0] {
case 2:
default:
return nil, fmt.Errorf("unknown stream version: 0x%x", ver[0])
}
return &Reader{mr: msgp.NewReader(r), majorV: ver[0], minorV: ver[1]}, nil
}
// SetPrivateKey will set the private key to allow stream decryption.
// This overrides any function set by PrivateKeyProvider.
func (r *Reader) SetPrivateKey(k *rsa.PrivateKey) {
r.privateFn = nil
r.private = k
}
// PrivateKeyProvider will ask for a private key matching the public key.
// If the function returns a nil private key the stream key will not be decrypted
// and if SkipEncrypted has been set any streams with this key will be silently skipped.
// This overrides any key set by SetPrivateKey.
func (r *Reader) PrivateKeyProvider(fn func(key *rsa.PublicKey) *rsa.PrivateKey) {
r.privateFn = fn
r.private = nil
}
// SkipEncrypted will skip encrypted streams if no private key has been set.
func (r *Reader) SkipEncrypted(b bool) {
r.skipEncrypted = b
}
// ReturnNonDecryptable will return non-decryptable stream headers.
// Streams are returned with ErrNoKey error.
// Streams with this error cannot be read, but the Skip function can be invoked.
// SkipEncrypted overrides this.
func (r *Reader) ReturnNonDecryptable(b bool) {
r.returnNonDec = b
}
// Stream returns the next stream.
type Stream struct {
io.Reader
Name string
Extra []byte
SentEncrypted bool
parent *Reader
}
// NextStream will return the next stream.
// Before calling this the previous stream must be read until EOF,
// or Skip() should have been called.
// Will return nil, io.EOF when there are no more streams.
func (r *Reader) NextStream() (*Stream, error) {
if r.err != nil {
return nil, r.err
}
if r.inStream {
return nil, errors.New("previous stream not read until EOF")
}
// Temp storage for blocks.
block := make([]byte, 1024)
for {
// Read block ID.
n, err := r.mr.ReadInt8()
if err != nil {
return nil, r.setErr(err)
}
id := blockID(n)
// Read block size
sz, err := r.mr.ReadUint32()
if err != nil {
return nil, r.setErr(err)
}
// Read block data
if cap(block) < int(sz) {
block = make([]byte, sz)
}
block = block[:sz]
_, err = io.ReadFull(r.mr, block)
if err != nil {
return nil, r.setErr(err)
}
// Parse block
switch id {
case blockPlainKey:
// Read plaintext key.
key, _, err := msgp.ReadBytesBytes(block, make([]byte, 0, 32))
if err != nil {
return nil, r.setErr(err)
}
if len(key) != 32 {
return nil, r.setErr(fmt.Errorf("unexpected key length: %d", len(key)))
}
// Set key for following streams.
r.key = (*[32]byte)(key)
case blockEncryptedKey:
// Read public key
publicKey, block, err := msgp.ReadBytesZC(block)
if err != nil {
return nil, r.setErr(err)
}
// Request private key if we have a custom function.
if r.privateFn != nil {
pk, err := x509.ParsePKCS1PublicKey(publicKey)
if err != nil {
return nil, r.setErr(err)
}
r.private = r.privateFn(pk)
if r.private == nil {
if r.skipEncrypted || r.returnNonDec {
r.key = nil
continue
}
return nil, r.setErr(errors.New("nil private key returned"))
}
}
// Read cipher key
cipherKey, _, err := msgp.ReadBytesZC(block)
if err != nil {
return nil, r.setErr(err)
}
if r.private == nil {
if r.skipEncrypted || r.returnNonDec {
r.key = nil
continue
}
return nil, r.setErr(errors.New("private key has not been set"))
}
// Decrypt stream key
key, err := rsa.DecryptOAEP(sha512.New(), rand.Reader, r.private, cipherKey, nil)
if err != nil {
if r.returnNonDec {
r.key = nil
continue
}
return nil, err
}
if len(key) != 32 {
return nil, r.setErr(fmt.Errorf("unexpected key length: %d", len(key)))
}
r.key = (*[32]byte)(key)
case blockPlainStream, blockEncStream:
// Read metadata
name, block, err := msgp.ReadStringBytes(block)
if err != nil {
return nil, r.setErr(err)
}
extra, block, err := msgp.ReadBytesBytes(block, nil)
if err != nil {
return nil, r.setErr(err)
}
c, block, err := msgp.ReadUint8Bytes(block)
if err != nil {
return nil, r.setErr(err)
}
checksum := checksumType(c)
if !checksum.valid() {
return nil, r.setErr(fmt.Errorf("unknown checksum type %d", checksum))
}
// Return plaintext stream
if id == blockPlainStream {
return &Stream{
Reader: r.newStreamReader(checksum),
Name: name,
Extra: extra,
parent: r,
}, nil
}
// Handle encrypted streams.
if r.key == nil {
if r.skipEncrypted {
if err := r.skipDataBlocks(); err != nil {
return nil, r.setErr(err)
}
continue
}
return &Stream{
SentEncrypted: true,
Reader: nil,
Name: name,
Extra: extra,
parent: r,
}, ErrNoKey
}
// Read stream nonce
nonce, _, err := msgp.ReadBytesZC(block)
if err != nil {
return nil, r.setErr(err)
}
stream, err := sio.AES_256_GCM.Stream(r.key[:])
if err != nil {
return nil, r.setErr(err)
}
// Check if nonce is expected length.
if len(nonce) != stream.NonceSize() {
return nil, r.setErr(fmt.Errorf("unexpected nonce length: %d", len(nonce)))
}
encr := stream.DecryptReader(r.newStreamReader(checksum), nonce, nil)
return &Stream{
SentEncrypted: true,
Reader: encr,
Name: name,
Extra: extra,
parent: r,
}, nil
case blockEOS:
return nil, errors.New("end-of-stream without being in stream")
case blockEOF:
return nil, io.EOF
case blockError:
msg, _, err := msgp.ReadStringBytes(block)
if err != nil {
return nil, r.setErr(err)
}
return nil, r.setErr(errors.New(msg))
default:
if id >= 0 {
return nil, fmt.Errorf("unknown block type: %d", id)
}
}
}
}
// skipDataBlocks reads data blocks until end.
func (r *Reader) skipDataBlocks() error {
for {
// Read block ID.
n, err := r.mr.ReadInt8()
if err != nil {
return err
}
id := blockID(n)
sz, err := r.mr.ReadUint32()
if err != nil {
return err
}
if id == blockError {
msg, err := r.mr.ReadString()
if err != nil {
return err
}
return errors.New(msg)
}
// Discard data
_, err = io.CopyN(io.Discard, r.mr, int64(sz))
if err != nil {
return err
}
switch id {
case blockDatablock:
// Skip data
case blockEOS:
// Done
r.inStream = false
return nil
default:
if id >= 0 {
return fmt.Errorf("unknown block type: %d", id)
}
}
}
}
// setErr sets a stateful error.
func (r *Reader) setErr(err error) error {
if r.err != nil {
return r.err
}
if err == nil {
return err
}
if errors.Is(err, io.EOF) {
r.err = io.ErrUnexpectedEOF
}
if false {
_, file, line, ok := runtime.Caller(1)
if ok {
err = fmt.Errorf("%s:%d: %w", file, line, err)
}
}
r.err = err
return err
}
type streamReader struct {
up *Reader
h xxhash.Digest
buf bytes.Buffer
tmp []byte
isEOF bool
check checksumType
}
// newStreamReader creates a stream reader that can be read to get all data blocks.
func (r *Reader) newStreamReader(ct checksumType) *streamReader {
sr := &streamReader{up: r, check: ct}
sr.h.Reset()
r.inStream = true
return sr
}
// Skip the remainder of the stream.
func (s *Stream) Skip() error {
if sr, ok := s.Reader.(*streamReader); ok {
sr.isEOF = true
sr.buf.Reset()
}
return s.parent.skipDataBlocks()
}
// Read will return data blocks as on stream.
func (r *streamReader) Read(b []byte) (int, error) {
if r.isEOF {
return 0, io.EOF
}
if r.up.err != nil {
return 0, r.up.err
}
for {
// If we have anything in the buffer return that first.
if r.buf.Len() > 0 {
n, err := r.buf.Read(b)
if err == io.EOF {
err = nil
}
return n, r.up.setErr(err)
}
// Read block
n, err := r.up.mr.ReadInt8()
if err != nil {
return 0, r.up.setErr(err)
}
id := blockID(n)
// Read size...
sz, err := r.up.mr.ReadUint32()
if err != nil {
return 0, r.up.setErr(err)
}
switch id {
case blockDatablock:
// Read block
buf, err := r.up.mr.ReadBytes(r.tmp[:0])
if err != nil {
return 0, r.up.setErr(err)
}
// Write to buffer and checksum
if r.check == checksumTypeXxhash {
r.h.Write(buf)
}
r.tmp = buf
r.buf.Write(buf)
case blockEOS:
// Verify stream checksum if any.
hash, err := r.up.mr.ReadBytes(nil)
if err != nil {
return 0, r.up.setErr(err)
}
switch r.check {
case checksumTypeXxhash:
got := r.h.Sum(nil)
if !bytes.Equal(hash, got) {
return 0, r.up.setErr(fmt.Errorf("checksum mismatch, want %s, got %s", hex.EncodeToString(hash), hex.EncodeToString(got)))
}
case checksumTypeNone:
default:
return 0, r.up.setErr(fmt.Errorf("unknown checksum id %d", r.check))
}
r.isEOF = true
r.up.inStream = false
return 0, io.EOF
case blockError:
msg, err := r.up.mr.ReadString()
if err != nil {
return 0, r.up.setErr(err)
}
return 0, r.up.setErr(errors.New(msg))
default:
if id >= 0 {
return 0, fmt.Errorf("unexpected block type: %d", id)
}
// Skip block...
_, err := io.CopyN(io.Discard, r.up.mr, int64(sz))
if err != nil {
return 0, r.up.setErr(err)
}
}
}
}