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Diffstat (limited to 'pkg/merkletree/merkletree.go')
-rw-r--r--pkg/merkletree/merkletree.go222
1 files changed, 172 insertions, 50 deletions
diff --git a/pkg/merkletree/merkletree.go b/pkg/merkletree/merkletree.go
index ccef83259..a6e698f57 100644
--- a/pkg/merkletree/merkletree.go
+++ b/pkg/merkletree/merkletree.go
@@ -123,45 +123,87 @@ func (layout Layout) blockOffset(level int, index int64) int64 {
return layout.levelOffset[level] + index*layout.blockSize
}
+// VerityDescriptor is a struct that is serialized and hashed to get a file's
+// root hash, which contains the root hash of the raw content and the file's
+// meatadata.
+type VerityDescriptor struct {
+ Name string
+ Mode uint32
+ UID uint32
+ GID uint32
+ RootHash []byte
+}
+
+func (d *VerityDescriptor) String() string {
+ return fmt.Sprintf("Name: %s, Mode: %d, UID: %d, GID: %d, RootHash: %v", d.Name, d.Mode, d.UID, d.GID, d.RootHash)
+}
+
+// GenerateParams contains the parameters used to generate a Merkle tree.
+type GenerateParams struct {
+ // File is a reader of the file to be hashed.
+ File io.ReadSeeker
+ // Size is the size of the file.
+ Size int64
+ // Name is the name of the target file.
+ Name string
+ // Mode is the mode of the target file.
+ Mode uint32
+ // UID is the user ID of the target file.
+ UID uint32
+ // GID is the group ID of the target file.
+ GID uint32
+ // TreeReader is a reader for the Merkle tree.
+ TreeReader io.ReadSeeker
+ // TreeWriter is a writer for the Merkle tree.
+ TreeWriter io.WriteSeeker
+ // DataAndTreeInSameFile is true if data and Merkle tree are in the same
+ // file, or false if Merkle tree is a separate file from data.
+ DataAndTreeInSameFile bool
+}
+
// Generate constructs a Merkle tree for the contents of data. The output is
// written to treeWriter. The treeReader should be able to read the tree after
// it has been written. That is, treeWriter and treeReader should point to the
// same underlying data but have separate cursors.
+//
+// Generate returns a hash of descriptor. The descriptor contains the file
+// metadata and the hash from file content.
+//
// Generate will modify the cursor for data, but always restores it to its
// original position upon exit. The cursor for tree is modified and not
// restored.
-func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, treeWriter io.WriteSeeker, dataAndTreeInSameFile bool) ([]byte, error) {
- layout := InitLayout(dataSize, dataAndTreeInSameFile)
+func Generate(params *GenerateParams) ([]byte, error) {
+ layout := InitLayout(params.Size, params.DataAndTreeInSameFile)
- numBlocks := (dataSize + layout.blockSize - 1) / layout.blockSize
+ numBlocks := (params.Size + layout.blockSize - 1) / layout.blockSize
// If the data is in the same file as the tree, zero pad the last data
// block.
- bytesInLastBlock := dataSize % layout.blockSize
- if dataAndTreeInSameFile && bytesInLastBlock != 0 {
+ bytesInLastBlock := params.Size % layout.blockSize
+ if params.DataAndTreeInSameFile && bytesInLastBlock != 0 {
zeroBuf := make([]byte, layout.blockSize-bytesInLastBlock)
- if _, err := treeWriter.Seek(0, io.SeekEnd); err != nil && err != io.EOF {
+ if _, err := params.TreeWriter.Seek(0, io.SeekEnd); err != nil && err != io.EOF {
return nil, err
}
- if _, err := treeWriter.Write(zeroBuf); err != nil {
+ if _, err := params.TreeWriter.Write(zeroBuf); err != nil {
return nil, err
}
}
// Store the current offset, so we can set it back once verification
// finishes.
- origOffset, err := data.Seek(0, io.SeekCurrent)
+ origOffset, err := params.File.Seek(0, io.SeekCurrent)
if err != nil {
return nil, err
}
- defer data.Seek(origOffset, io.SeekStart)
+ defer params.File.Seek(origOffset, io.SeekStart)
// Read from the beginning of both data and treeReader.
- if _, err := data.Seek(0, io.SeekStart); err != nil && err != io.EOF {
+ if _, err := params.File.Seek(0, io.SeekStart); err != nil && err != io.EOF {
return nil, err
}
- if _, err := treeReader.Seek(0, io.SeekStart); err != nil && err != io.EOF {
+ if _, err := params.TreeReader.Seek(0, io.SeekStart); err != nil && err != io.EOF {
return nil, err
}
@@ -176,11 +218,11 @@ func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, tree
if level == 0 {
// Read data block from the target file since level 0 includes hashes
// of blocks in the input data.
- n, err = data.Read(buf)
+ n, err = params.File.Read(buf)
} else {
// Read data block from the tree file since levels higher than 0 are
// hashing the lower level hashes.
- n, err = treeReader.Read(buf)
+ n, err = params.TreeReader.Read(buf)
}
// err is populated as long as the bytes read is smaller than the buffer
@@ -200,7 +242,7 @@ func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, tree
}
// Write the generated hash to the end of the tree file.
- if _, err = treeWriter.Write(digest[:]); err != nil {
+ if _, err = params.TreeWriter.Write(digest[:]); err != nil {
return nil, err
}
}
@@ -208,45 +250,124 @@ func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, tree
// remaining of the last block. But no need to do so for root.
if level != layout.rootLevel() && numBlocks%layout.hashesPerBlock() != 0 {
zeroBuf := make([]byte, layout.blockSize-(numBlocks%layout.hashesPerBlock())*layout.digestSize)
- if _, err := treeWriter.Write(zeroBuf[:]); err != nil {
+ if _, err := params.TreeWriter.Write(zeroBuf[:]); err != nil {
return nil, err
}
}
numBlocks = (numBlocks + layout.hashesPerBlock() - 1) / layout.hashesPerBlock()
}
- return root, nil
+ descriptor := VerityDescriptor{
+ Name: params.Name,
+ Mode: params.Mode,
+ UID: params.UID,
+ GID: params.GID,
+ RootHash: root,
+ }
+ ret := sha256.Sum256([]byte(descriptor.String()))
+ return ret[:], nil
+}
+
+// VerifyParams contains the params used to verify a portion of a file against
+// a Merkle tree.
+type VerifyParams struct {
+ // Out will be filled with verified data.
+ Out io.Writer
+ // File is a handler on the file to be verified.
+ File io.ReadSeeker
+ // tree is a handler on the Merkle tree used to verify file.
+ Tree io.ReadSeeker
+ // Size is the size of the file.
+ Size int64
+ // Name is the name of the target file.
+ Name string
+ // Mode is the mode of the target file.
+ Mode uint32
+ // UID is the user ID of the target file.
+ UID uint32
+ // GID is the group ID of the target file.
+ GID uint32
+ // ReadOffset is the offset of the data range to be verified.
+ ReadOffset int64
+ // ReadSize is the size of the data range to be verified.
+ ReadSize int64
+ // ExpectedRoot is a trusted hash for the file. It is compared with the
+ // calculated root hash to verify the content.
+ ExpectedRoot []byte
+ // DataAndTreeInSameFile is true if data and Merkle tree are in the same
+ // file, or false if Merkle tree is a separate file from data.
+ DataAndTreeInSameFile bool
+}
+
+// verifyDescriptor generates a hash from descriptor, and compares it with
+// expectedRoot.
+func verifyDescriptor(descriptor VerityDescriptor, expectedRoot []byte) error {
+ h := sha256.Sum256([]byte(descriptor.String()))
+ if !bytes.Equal(h[:], expectedRoot) {
+ return fmt.Errorf("unexpected root hash")
+ }
+ return nil
+}
+
+// verifyMetadata verifies the metadata by hashing a descriptor that contains
+// the metadata and compare the generated hash with expectedRoot.
+//
+// For verifyMetadata, params.data is not needed. It only accesses params.tree
+// for the raw root hash.
+func verifyMetadata(params *VerifyParams, layout Layout) error {
+ if _, err := params.Tree.Seek(layout.blockOffset(layout.rootLevel(), 0 /* index */), io.SeekStart); err != nil {
+ return fmt.Errorf("failed to seek to root hash: %w", err)
+ }
+ root := make([]byte, layout.digestSize)
+ if _, err := params.Tree.Read(root); err != nil {
+ return fmt.Errorf("failed to read root hash: %w", err)
+ }
+ descriptor := VerityDescriptor{
+ Name: params.Name,
+ Mode: params.Mode,
+ UID: params.UID,
+ GID: params.GID,
+ RootHash: root,
+ }
+ return verifyDescriptor(descriptor, params.ExpectedRoot)
}
// Verify verifies the content read from data with offset. The content is
// verified against tree. If content spans across multiple blocks, each block is
// verified. Verification fails if the hash of the data does not match the tree
// at any level, or if the final root hash does not match expectedRoot.
-// Once the data is verified, it will be written using w.
+// Once the data is verified, it will be written using params.Out.
+//
+// Verify checks for both target file content and metadata. If readSize is 0,
+// only metadata is checked.
+//
// Verify will modify the cursor for data, but always restores it to its
// original position upon exit. The cursor for tree is modified and not
// restored.
-func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset int64, readSize int64, expectedRoot []byte, dataAndTreeInSameFile bool) (int64, error) {
- if readSize <= 0 {
- return 0, fmt.Errorf("Unexpected read size: %d", readSize)
+func Verify(params *VerifyParams) (int64, error) {
+ if params.ReadSize < 0 {
+ return 0, fmt.Errorf("unexpected read size: %d", params.ReadSize)
+ }
+ layout := InitLayout(int64(params.Size), params.DataAndTreeInSameFile)
+ if params.ReadSize == 0 {
+ return 0, verifyMetadata(params, layout)
}
- layout := InitLayout(int64(dataSize), dataAndTreeInSameFile)
// Calculate the index of blocks that includes the target range in input
// data.
- firstDataBlock := readOffset / layout.blockSize
- lastDataBlock := (readOffset + readSize - 1) / layout.blockSize
+ firstDataBlock := params.ReadOffset / layout.blockSize
+ lastDataBlock := (params.ReadOffset + params.ReadSize - 1) / layout.blockSize
// Store the current offset, so we can set it back once verification
// finishes.
- origOffset, err := data.Seek(0, io.SeekCurrent)
+ origOffset, err := params.File.Seek(0, io.SeekCurrent)
if err != nil {
- return 0, fmt.Errorf("Find current data offset failed: %v", err)
+ return 0, fmt.Errorf("find current data offset failed: %w", err)
}
- defer data.Seek(origOffset, io.SeekStart)
+ defer params.File.Seek(origOffset, io.SeekStart)
// Move to the first block that contains target data.
- if _, err := data.Seek(firstDataBlock*layout.blockSize, io.SeekStart); err != nil {
- return 0, fmt.Errorf("Seek to datablock start failed: %v", err)
+ if _, err := params.File.Seek(firstDataBlock*layout.blockSize, io.SeekStart); err != nil {
+ return 0, fmt.Errorf("seek to datablock start failed: %w", err)
}
buf := make([]byte, layout.blockSize)
@@ -255,7 +376,7 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
for i := firstDataBlock; i <= lastDataBlock; i++ {
// Read a block that includes all or part of target range in
// input data.
- bytesRead, err := data.Read(buf)
+ bytesRead, err := params.File.Read(buf)
readErr = err
// If at the end of input data and all previous blocks are
// verified, return the verified input data and EOF.
@@ -263,7 +384,7 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
break
}
if readErr != nil && readErr != io.EOF {
- return 0, fmt.Errorf("Read from data failed: %v", err)
+ return 0, fmt.Errorf("read from data failed: %w", err)
}
// If this is the end of file, zero the remaining bytes in buf,
// otherwise they are still from the previous block.
@@ -274,22 +395,29 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
buf[j] = 0
}
}
- if err := verifyBlock(tree, layout, buf, i, expectedRoot); err != nil {
+ descriptor := VerityDescriptor{
+ Name: params.Name,
+ Mode: params.Mode,
+ UID: params.UID,
+ GID: params.GID,
+ }
+ if err := verifyBlock(params.Tree, descriptor, layout, buf, i, params.ExpectedRoot); err != nil {
return 0, err
}
+
// startOff is the beginning of the read range within the
// current data block. Note that for all blocks other than the
// first, startOff should be 0.
startOff := int64(0)
if i == firstDataBlock {
- startOff = readOffset % layout.blockSize
+ startOff = params.ReadOffset % layout.blockSize
}
// endOff is the end of the read range within the current data
// block. Note that for all blocks other than the last, endOff
// should be the block size.
endOff := layout.blockSize
if i == lastDataBlock {
- endOff = (readOffset+readSize-1)%layout.blockSize + 1
+ endOff = (params.ReadOffset+params.ReadSize-1)%layout.blockSize + 1
}
// If the provided size exceeds the end of input data, we should
// only copy the parts in buf that's part of input data.
@@ -299,7 +427,7 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
if endOff > int64(bytesRead) {
endOff = int64(bytesRead)
}
- n, err := w.Write(buf[startOff:endOff])
+ n, err := params.Out.Write(buf[startOff:endOff])
if err != nil {
return total, err
}
@@ -313,9 +441,11 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
// original data. The block is verified through each level of the tree. It
// fails if the calculated hash from block is different from any level of
// hashes stored in tree. And the final root hash is compared with
-// expectedRoot. verifyBlock modifies the cursor for tree. Users needs to
-// maintain the cursor if intended.
-func verifyBlock(tree io.ReadSeeker, layout Layout, dataBlock []byte, blockIndex int64, expectedRoot []byte) error {
+// expectedRoot.
+//
+// verifyBlock modifies the cursor for tree. Users needs to maintain the cursor
+// if intended.
+func verifyBlock(tree io.ReadSeeker, descriptor VerityDescriptor, layout Layout, dataBlock []byte, blockIndex int64, expectedRoot []byte) error {
if len(dataBlock) != int(layout.blockSize) {
return fmt.Errorf("incorrect block size")
}
@@ -352,21 +482,13 @@ func verifyBlock(tree io.ReadSeeker, layout Layout, dataBlock []byte, blockIndex
}
if !bytes.Equal(digest, expectedDigest) {
- return fmt.Errorf("Verification failed")
- }
-
- // If this is the root layer, no need to generate next level
- // hash.
- if level == layout.rootLevel() {
- break
+ return fmt.Errorf("verification failed")
}
blockIndex = blockIndex / layout.hashesPerBlock()
}
- // Verification for the tree succeeded. Now compare the root hash in the
- // tree with expectedRoot.
- if !bytes.Equal(digest[:], expectedRoot) {
- return fmt.Errorf("Verification failed")
- }
- return nil
+ // Verification for the tree succeeded. Now hash the descriptor with
+ // the root hash and compare it with expectedRoot.
+ descriptor.RootHash = digest
+ return verifyDescriptor(descriptor, expectedRoot)
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 05:50:21 +0000