From 2b8cbd944149afe51fadddbd67ee4499d1d86250 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Sat, 6 Feb 2016 19:20:54 +0100
Subject: Major refactoring: Split up "cryptfs" into several internal packages
"git status" for reference:
deleted: cryptfs/cryptfs.go
deleted: cryptfs/names_core.go
modified: integration_tests/cli_test.go
modified: integration_tests/helpers.go
renamed: cryptfs/config_file.go -> internal/configfile/config_file.go
renamed: cryptfs/config_test.go -> internal/configfile/config_test.go
renamed: cryptfs/config_test/.gitignore -> internal/configfile/config_test/.gitignore
renamed: cryptfs/config_test/PlaintextNames.conf -> internal/configfile/config_test/PlaintextNames.conf
renamed: cryptfs/config_test/StrangeFeature.conf -> internal/configfile/config_test/StrangeFeature.conf
renamed: cryptfs/config_test/v1.conf -> internal/configfile/config_test/v1.conf
renamed: cryptfs/config_test/v2.conf -> internal/configfile/config_test/v2.conf
renamed: cryptfs/kdf.go -> internal/configfile/kdf.go
renamed: cryptfs/kdf_test.go -> internal/configfile/kdf_test.go
renamed: cryptfs/cryptfs_content.go -> internal/contentenc/content.go
new file: internal/contentenc/content_api.go
renamed: cryptfs/content_test.go -> internal/contentenc/content_test.go
renamed: cryptfs/file_header.go -> internal/contentenc/file_header.go
renamed: cryptfs/intrablock.go -> internal/contentenc/intrablock.go
renamed: cryptfs/address_translation.go -> internal/contentenc/offsets.go
new file: internal/cryptocore/crypto_api.go
renamed: cryptfs/gcm_go1.4.go -> internal/cryptocore/gcm_go1.4.go
renamed: cryptfs/gcm_go1.5.go -> internal/cryptocore/gcm_go1.5.go
renamed: cryptfs/nonce.go -> internal/cryptocore/nonce.go
renamed: cryptfs/openssl_aead.go -> internal/cryptocore/openssl_aead.go
renamed: cryptfs/openssl_benchmark.bash -> internal/cryptocore/openssl_benchmark.bash
renamed: cryptfs/openssl_test.go -> internal/cryptocore/openssl_test.go
new file: internal/nametransform/name_api.go
new file: internal/nametransform/names_core.go
renamed: cryptfs/names_diriv.go -> internal/nametransform/names_diriv.go
renamed: cryptfs/names_noiv.go -> internal/nametransform/names_noiv.go
renamed: cryptfs/names_test.go -> internal/nametransform/names_test.go
new file: internal/nametransform/pad16.go
renamed: cryptfs/log.go -> internal/toggledlog/log.go
renamed: cryptfs/log_go1.4.go -> internal/toggledlog/log_go1.4.go
renamed: cryptfs/log_go1.5.go -> internal/toggledlog/log_go1.5.go
modified: main.go
modified: masterkey.go
modified: pathfs_frontend/file.go
modified: pathfs_frontend/file_holes.go
modified: pathfs_frontend/fs.go
modified: pathfs_frontend/fs_dir.go
modified: pathfs_frontend/names.go
modified: test.bash
---
internal/contentenc/content.go | 116 ++++++++++++++++++++++++++++++++++++
internal/contentenc/content_api.go | 31 ++++++++++
internal/contentenc/content_test.go | 91 ++++++++++++++++++++++++++++
internal/contentenc/file_header.go | 60 +++++++++++++++++++
internal/contentenc/intrablock.go | 51 ++++++++++++++++
internal/contentenc/offsets.go | 97 ++++++++++++++++++++++++++++++
6 files changed, 446 insertions(+)
create mode 100644 internal/contentenc/content.go
create mode 100644 internal/contentenc/content_api.go
create mode 100644 internal/contentenc/content_test.go
create mode 100644 internal/contentenc/file_header.go
create mode 100644 internal/contentenc/intrablock.go
create mode 100644 internal/contentenc/offsets.go
(limited to 'internal/contentenc')
diff --git a/internal/contentenc/content.go b/internal/contentenc/content.go
new file mode 100644
index 0000000..14135a2
--- /dev/null
+++ b/internal/contentenc/content.go
@@ -0,0 +1,116 @@
+package contentenc
+
+// File content encryption / decryption
+
+import (
+ "encoding/binary"
+ "bytes"
+ "encoding/hex"
+ "errors"
+
+ "github.com/rfjakob/gocryptfs/internal/toggledlog"
+)
+
+// DecryptBlocks - Decrypt a number of blocks
+func (be *ContentEnc) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, fileId []byte) ([]byte, error) {
+ cBuf := bytes.NewBuffer(ciphertext)
+ var err error
+ var pBuf bytes.Buffer
+ for cBuf.Len() > 0 {
+ cBlock := cBuf.Next(int(be.cipherBS))
+ var pBlock []byte
+ pBlock, err = be.DecryptBlock(cBlock, firstBlockNo, fileId)
+ if err != nil {
+ break
+ }
+ pBuf.Write(pBlock)
+ firstBlockNo++
+ }
+ return pBuf.Bytes(), err
+}
+
+// DecryptBlock - Verify and decrypt GCM block
+//
+// Corner case: A full-sized block of all-zero ciphertext bytes is translated
+// to an all-zero plaintext block, i.e. file hole passtrough.
+func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileId []byte) ([]byte, error) {
+
+ // Empty block?
+ if len(ciphertext) == 0 {
+ return ciphertext, nil
+ }
+
+ // All-zero block?
+ if bytes.Equal(ciphertext, be.allZeroBlock) {
+ toggledlog.Debug.Printf("DecryptBlock: file hole encountered")
+ return make([]byte, be.plainBS), nil
+ }
+
+ if len(ciphertext) < be.cryptoCore.IVLen {
+ toggledlog.Warn.Printf("DecryptBlock: Block is too short: %d bytes", len(ciphertext))
+ return nil, errors.New("Block is too short")
+ }
+
+ // Extract nonce
+ nonce := ciphertext[:be.cryptoCore.IVLen]
+ ciphertextOrig := ciphertext
+ ciphertext = ciphertext[be.cryptoCore.IVLen:]
+
+ // Decrypt
+ var plaintext []byte
+ aData := make([]byte, 8)
+ aData = append(aData, fileId...)
+ binary.BigEndian.PutUint64(aData, blockNo)
+ plaintext, err := be.cryptoCore.Gcm.Open(plaintext, nonce, ciphertext, aData)
+
+ if err != nil {
+ toggledlog.Warn.Printf("DecryptBlock: %s, len=%d", err.Error(), len(ciphertextOrig))
+ toggledlog.Debug.Println(hex.Dump(ciphertextOrig))
+ return nil, err
+ }
+
+ return plaintext, nil
+}
+
+// encryptBlock - Encrypt and add IV and MAC
+func (be *ContentEnc) EncryptBlock(plaintext []byte, blockNo uint64, fileID []byte) []byte {
+
+ // Empty block?
+ if len(plaintext) == 0 {
+ return plaintext
+ }
+
+ // Get fresh nonce
+ nonce := be.cryptoCore.GcmIVGen.Get()
+
+ // Authenticate block with block number and file ID
+ aData := make([]byte, 8)
+ binary.BigEndian.PutUint64(aData, blockNo)
+ aData = append(aData, fileID...)
+
+ // Encrypt plaintext and append to nonce
+ ciphertext := be.cryptoCore.Gcm.Seal(nonce, nonce, plaintext, aData)
+
+ return ciphertext
+}
+
+// MergeBlocks - Merge newData into oldData at offset
+// New block may be bigger than both newData and oldData
+func (be *ContentEnc) MergeBlocks(oldData []byte, newData []byte, offset int) []byte {
+
+ // Make block of maximum size
+ out := make([]byte, be.plainBS)
+
+ // Copy old and new data into it
+ copy(out, oldData)
+ l := len(newData)
+ copy(out[offset:offset+l], newData)
+
+ // Crop to length
+ outLen := len(oldData)
+ newLen := offset + len(newData)
+ if outLen < newLen {
+ outLen = newLen
+ }
+ return out[0:outLen]
+}
diff --git a/internal/contentenc/content_api.go b/internal/contentenc/content_api.go
new file mode 100644
index 0000000..1700d35
--- /dev/null
+++ b/internal/contentenc/content_api.go
@@ -0,0 +1,31 @@
+package contentenc
+
+import "github.com/rfjakob/gocryptfs/internal/cryptocore"
+
+type ContentEnc struct {
+ // Cryptographic primitives
+ cryptoCore *cryptocore.CryptoCore
+ // Plaintext block size
+ plainBS uint64
+ // Ciphertext block size
+ cipherBS uint64
+ // All-zero block of size cipherBS, for fast compares
+ allZeroBlock []byte
+}
+
+func New(cc *cryptocore.CryptoCore, plainBS uint64) *ContentEnc {
+
+ cipherBS := plainBS + uint64(cc.IVLen) + cryptocore.AuthTagLen
+
+ return &ContentEnc{
+ cryptoCore: cc,
+ plainBS: plainBS,
+ cipherBS: cipherBS,
+ allZeroBlock: make([]byte, cipherBS),
+ }
+}
+
+
+func (be *ContentEnc) PlainBS() uint64 {
+ return be.plainBS
+}
diff --git a/internal/contentenc/content_test.go b/internal/contentenc/content_test.go
new file mode 100644
index 0000000..70ad58d
--- /dev/null
+++ b/internal/contentenc/content_test.go
@@ -0,0 +1,91 @@
+package contentenc
+
+import (
+ "testing"
+)
+
+type testRange struct {
+ offset uint64
+ length uint64
+}
+
+func TestSplitRange(t *testing.T) {
+ var ranges []testRange
+
+ ranges = append(ranges, testRange{0, 70000},
+ testRange{0, 10},
+ testRange{234, 6511},
+ testRange{65444, 54},
+ testRange{0, 1024 * 1024},
+ testRange{0, 65536},
+ testRange{6654, 8945})
+
+ key := make([]byte, KEY_LEN)
+ f := NewCryptFS(key, true, false, true)
+
+ for _, r := range ranges {
+ parts := f.ExplodePlainRange(r.offset, r.length)
+ var lastBlockNo uint64 = 1 << 63
+ for _, p := range parts {
+ if p.BlockNo == lastBlockNo {
+ t.Errorf("Duplicate block number %d", p.BlockNo)
+ }
+ lastBlockNo = p.BlockNo
+ if p.Length > DEFAULT_PLAINBS || p.Skip >= DEFAULT_PLAINBS {
+ t.Errorf("Test fail: n=%d, length=%d, offset=%d\n", p.BlockNo, p.Length, p.Skip)
+ }
+ }
+ }
+}
+
+func TestCiphertextRange(t *testing.T) {
+ var ranges []testRange
+
+ ranges = append(ranges, testRange{0, 70000},
+ testRange{0, 10},
+ testRange{234, 6511},
+ testRange{65444, 54},
+ testRange{6654, 8945})
+
+ key := make([]byte, KEY_LEN)
+ f := NewCryptFS(key, true, false, true)
+
+ for _, r := range ranges {
+
+ blocks := f.ExplodePlainRange(r.offset, r.length)
+ alignedOffset, alignedLength := blocks[0].JointCiphertextRange(blocks)
+ skipBytes := blocks[0].Skip
+
+ if alignedLength < r.length {
+ t.Errorf("alignedLength=%d is smaller than length=%d", alignedLength, r.length)
+ }
+ if (alignedOffset-HEADER_LEN)%f.cipherBS != 0 {
+ t.Errorf("alignedOffset=%d is not aligned", alignedOffset)
+ }
+ if r.offset%f.plainBS != 0 && skipBytes == 0 {
+ t.Errorf("skipBytes=0")
+ }
+ }
+}
+
+func TestBlockNo(t *testing.T) {
+ key := make([]byte, KEY_LEN)
+ f := NewCryptFS(key, true, false, true)
+
+ b := f.CipherOffToBlockNo(788)
+ if b != 0 {
+ t.Errorf("actual: %d", b)
+ }
+ b = f.CipherOffToBlockNo(HEADER_LEN + f.cipherBS)
+ if b != 1 {
+ t.Errorf("actual: %d", b)
+ }
+ b = f.PlainOffToBlockNo(788)
+ if b != 0 {
+ t.Errorf("actual: %d", b)
+ }
+ b = f.PlainOffToBlockNo(f.plainBS)
+ if b != 1 {
+ t.Errorf("actual: %d", b)
+ }
+}
diff --git a/internal/contentenc/file_header.go b/internal/contentenc/file_header.go
new file mode 100644
index 0000000..8a9dd2c
--- /dev/null
+++ b/internal/contentenc/file_header.go
@@ -0,0 +1,60 @@
+package contentenc
+
+// Per-file header
+//
+// Format: [ "Version" uint16 big endian ] [ "Id" 16 random bytes ]
+
+import (
+ "encoding/binary"
+ "fmt"
+
+ "github.com/rfjakob/gocryptfs/internal/cryptocore"
+)
+
+const (
+ // Current On-Disk-Format version
+ CurrentVersion = 2
+
+ HEADER_VERSION_LEN = 2 // uint16
+ HEADER_ID_LEN = 16 // 128 bit random file id
+ HEADER_LEN = HEADER_VERSION_LEN + HEADER_ID_LEN // Total header length
+)
+
+type FileHeader struct {
+ Version uint16
+ Id []byte
+}
+
+// Pack - serialize fileHeader object
+func (h *FileHeader) Pack() []byte {
+ if len(h.Id) != HEADER_ID_LEN || h.Version != CurrentVersion {
+ panic("FileHeader object not properly initialized")
+ }
+ buf := make([]byte, HEADER_LEN)
+ binary.BigEndian.PutUint16(buf[0:HEADER_VERSION_LEN], h.Version)
+ copy(buf[HEADER_VERSION_LEN:], h.Id)
+ return buf
+
+}
+
+// ParseHeader - parse "buf" into fileHeader object
+func ParseHeader(buf []byte) (*FileHeader, error) {
+ if len(buf) != HEADER_LEN {
+ return nil, fmt.Errorf("ParseHeader: invalid length: got %d, want %d", len(buf), HEADER_LEN)
+ }
+ var h FileHeader
+ h.Version = binary.BigEndian.Uint16(buf[0:HEADER_VERSION_LEN])
+ if h.Version != CurrentVersion {
+ return nil, fmt.Errorf("ParseHeader: invalid version: got %d, want %d", h.Version, CurrentVersion)
+ }
+ h.Id = buf[HEADER_VERSION_LEN:]
+ return &h, nil
+}
+
+// RandomHeader - create new fileHeader object with random Id
+func RandomHeader() *FileHeader {
+ var h FileHeader
+ h.Version = CurrentVersion
+ h.Id = cryptocore.RandBytes(HEADER_ID_LEN)
+ return &h
+}
diff --git a/internal/contentenc/intrablock.go b/internal/contentenc/intrablock.go
new file mode 100644
index 0000000..330b980
--- /dev/null
+++ b/internal/contentenc/intrablock.go
@@ -0,0 +1,51 @@
+package contentenc
+
+// intraBlock identifies a part of a file block
+type intraBlock struct {
+ BlockNo uint64 // Block number in file
+ Skip uint64 // Offset into block plaintext
+ Length uint64 // Length of data from this block
+ fs *ContentEnc
+}
+
+// isPartial - is the block partial? This means we have to do read-modify-write.
+func (ib *intraBlock) IsPartial() bool {
+ if ib.Skip > 0 || ib.Length < ib.fs.plainBS {
+ return true
+ }
+ return false
+}
+
+// CiphertextRange - get byte range in ciphertext file corresponding to BlockNo
+// (complete block)
+func (ib *intraBlock) CiphertextRange() (offset uint64, length uint64) {
+ return ib.fs.BlockNoToCipherOff(ib.BlockNo), ib.fs.cipherBS
+}
+
+// PlaintextRange - get byte range in plaintext corresponding to BlockNo
+// (complete block)
+func (ib *intraBlock) PlaintextRange() (offset uint64, length uint64) {
+ return ib.fs.BlockNoToPlainOff(ib.BlockNo), ib.fs.plainBS
+}
+
+// CropBlock - crop a potentially larger plaintext block down to the relevant part
+func (ib *intraBlock) CropBlock(d []byte) []byte {
+ lenHave := len(d)
+ lenWant := int(ib.Skip + ib.Length)
+ if lenHave < lenWant {
+ return d[ib.Skip:lenHave]
+ }
+ return d[ib.Skip:lenWant]
+}
+
+// Ciphertext range corresponding to the sum of all "blocks" (complete blocks)
+func (ib *intraBlock) JointCiphertextRange(blocks []intraBlock) (offset uint64, length uint64) {
+ firstBlock := blocks[0]
+ lastBlock := blocks[len(blocks)-1]
+
+ offset = ib.fs.BlockNoToCipherOff(firstBlock.BlockNo)
+ offsetLast := ib.fs.BlockNoToCipherOff(lastBlock.BlockNo)
+ length = offsetLast + ib.fs.cipherBS - offset
+
+ return offset, length
+}
diff --git a/internal/contentenc/offsets.go b/internal/contentenc/offsets.go
new file mode 100644
index 0000000..1b5952f
--- /dev/null
+++ b/internal/contentenc/offsets.go
@@ -0,0 +1,97 @@
+package contentenc
+
+import (
+ "github.com/rfjakob/gocryptfs/internal/toggledlog"
+)
+
+// Contentenc methods that translate offsets between ciphertext and plaintext
+
+// get the block number at plain-text offset
+func (be *ContentEnc) PlainOffToBlockNo(plainOffset uint64) uint64 {
+ return plainOffset / be.plainBS
+}
+
+// get the block number at ciphter-text offset
+func (be *ContentEnc) CipherOffToBlockNo(cipherOffset uint64) uint64 {
+ return (cipherOffset - HEADER_LEN) / be.cipherBS
+}
+
+// get ciphertext offset of block "blockNo"
+func (be *ContentEnc) BlockNoToCipherOff(blockNo uint64) uint64 {
+ return HEADER_LEN + blockNo*be.cipherBS
+}
+
+// get plaintext offset of block "blockNo"
+func (be *ContentEnc) BlockNoToPlainOff(blockNo uint64) uint64 {
+ return blockNo * be.plainBS
+}
+
+// PlainSize - calculate plaintext size from ciphertext size
+func (be *ContentEnc) CipherSizeToPlainSize(cipherSize uint64) uint64 {
+
+ // Zero sized files stay zero-sized
+ if cipherSize == 0 {
+ return 0
+ }
+
+ if cipherSize == HEADER_LEN {
+ toggledlog.Warn.Printf("cipherSize %d == header size: interrupted write?\n", cipherSize)
+ return 0
+ }
+
+ if cipherSize < HEADER_LEN {
+ toggledlog.Warn.Printf("cipherSize %d < header size: corrupt file\n", cipherSize)
+ return 0
+ }
+
+ // Block number at last byte
+ blockNo := be.CipherOffToBlockNo(cipherSize - 1)
+ blockCount := blockNo + 1
+
+ overhead := be.BlockOverhead()*blockCount + HEADER_LEN
+
+ return cipherSize - overhead
+}
+
+// CipherSize - calculate ciphertext size from plaintext size
+func (be *ContentEnc) PlainSizeToCipherSize(plainSize uint64) uint64 {
+
+ // Block number at last byte
+ blockNo := be.PlainOffToBlockNo(plainSize - 1)
+ blockCount := blockNo + 1
+
+ overhead := be.BlockOverhead()*blockCount + HEADER_LEN
+
+ return plainSize + overhead
+}
+
+// Split a plaintext byte range into (possibly partial) blocks
+func (be *ContentEnc) ExplodePlainRange(offset uint64, length uint64) []intraBlock {
+ var blocks []intraBlock
+ var nextBlock intraBlock
+ nextBlock.fs = be
+
+ for length > 0 {
+ nextBlock.BlockNo = be.PlainOffToBlockNo(offset)
+ nextBlock.Skip = offset - be.BlockNoToPlainOff(nextBlock.BlockNo)
+
+ // Minimum of remaining data and remaining space in the block
+ nextBlock.Length = MinUint64(length, be.plainBS-nextBlock.Skip)
+
+ blocks = append(blocks, nextBlock)
+ offset += nextBlock.Length
+ length -= nextBlock.Length
+ }
+ return blocks
+}
+
+func (be *ContentEnc) BlockOverhead() uint64 {
+ return be.cipherBS - be.plainBS
+}
+
+func MinUint64(x uint64, y uint64) uint64 {
+ if x < y {
+ return x
+ }
+ return y
+}
--
cgit v1.2.3