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-rw-r--r--pkg/merkletree/BUILD1
-rw-r--r--pkg/merkletree/merkletree.go259
-rw-r--r--pkg/merkletree/merkletree_test.go319
3 files changed, 495 insertions, 84 deletions
diff --git a/pkg/merkletree/BUILD b/pkg/merkletree/BUILD
index 5b0e4143a..a8fcb2e19 100644
--- a/pkg/merkletree/BUILD
+++ b/pkg/merkletree/BUILD
@@ -5,6 +5,7 @@ package(licenses = ["notice"])
go_library(
name = "merkletree",
srcs = ["merkletree.go"],
+ visibility = ["//pkg/sentry:internal"],
deps = ["//pkg/usermem"],
)
diff --git a/pkg/merkletree/merkletree.go b/pkg/merkletree/merkletree.go
index 906f67943..955c9c473 100644
--- a/pkg/merkletree/merkletree.go
+++ b/pkg/merkletree/merkletree.go
@@ -16,7 +16,9 @@
package merkletree
import (
+ "bytes"
"crypto/sha256"
+ "fmt"
"io"
"gvisor.dev/gvisor/pkg/usermem"
@@ -27,50 +29,78 @@ const (
sha256DigestSize = 32
)
-// Size defines the scale of a Merkle tree.
-type Size struct {
+// Layout defines the scale of a Merkle tree.
+type Layout struct {
// blockSize is the size of a data block to be hashed.
blockSize int64
// digestSize is the size of a generated hash.
digestSize int64
- // hashesPerBlock is the number of hashes in a block. For example, if
- // blockSize is 4096 bytes, and digestSize is 32 bytes, there will be 128
- // hashesPerBlock. Therefore 128 hashes in a lower level will be put into a
- // block and generate a single hash in an upper level.
- hashesPerBlock int64
- // levelStart is the start block index of each level. The number of levels in
- // the tree is the length of the slice. The leafs (level 0) are hashes of
- // blocks in the input data. The levels above are hashes of lower level
- // hashes. The highest level is the root hash.
- levelStart []int64
+ // levelOffset contains the offset of the begnning of each level in
+ // bytes. The number of levels in the tree is the length of the slice.
+ // The leaf nodes (level 0) contain hashes of blocks of the input data.
+ // Each level N contains hashes of the blocks in level N-1. The highest
+ // level is the root hash.
+ levelOffset []int64
}
-// MakeSize initializes and returns a new Size object describing the structure
-// of a tree. dataSize specifies the number of the file system size in bytes.
-func MakeSize(dataSize int64) Size {
- size := Size{
+// InitLayout initializes and returns a new Layout object describing the structure
+// of a tree. dataSize specifies the size of input data in bytes.
+func InitLayout(dataSize int64) Layout {
+ layout := Layout{
blockSize: usermem.PageSize,
// TODO(b/156980949): Allow config other hash methods (SHA384/SHA512).
- digestSize: sha256DigestSize,
- hashesPerBlock: usermem.PageSize / sha256DigestSize,
+ digestSize: sha256DigestSize,
}
- numBlocks := (dataSize + size.blockSize - 1) / size.blockSize
- level := int64(0)
+ numBlocks := (dataSize + layout.blockSize - 1) / layout.blockSize
+ level := 0
offset := int64(0)
- // Calcuate the number of levels in the Merkle tree and the beginning offset
- // of each level. Level 0 is the level directly above the data blocks, while
- // level NumLevels - 1 is the root.
+ // Calculate the number of levels in the Merkle tree and the beginning
+ // offset of each level. Level 0 consists of the leaf nodes that
+ // contain the hashes of the data blocks, while level numLevels - 1 is
+ // the root.
for numBlocks > 1 {
- size.levelStart = append(size.levelStart, offset)
+ layout.levelOffset = append(layout.levelOffset, offset*layout.blockSize)
// Round numBlocks up to fill up a block.
- numBlocks += (size.hashesPerBlock - numBlocks%size.hashesPerBlock) % size.hashesPerBlock
- offset += numBlocks / size.hashesPerBlock
- numBlocks = numBlocks / size.hashesPerBlock
+ numBlocks += (layout.hashesPerBlock() - numBlocks%layout.hashesPerBlock()) % layout.hashesPerBlock()
+ offset += numBlocks / layout.hashesPerBlock()
+ numBlocks = numBlocks / layout.hashesPerBlock()
level++
}
- size.levelStart = append(size.levelStart, offset)
- return size
+ layout.levelOffset = append(layout.levelOffset, offset*layout.blockSize)
+ return layout
+}
+
+// hashesPerBlock() returns the number of digests in each block. For example,
+// if blockSize is 4096 bytes, and digestSize is 32 bytes, there will be 128
+// hashesPerBlock. Therefore 128 hashes in one level will be combined in one
+// hash in the level above.
+func (layout Layout) hashesPerBlock() int64 {
+ return layout.blockSize / layout.digestSize
+}
+
+// numLevels returns the total number of levels in the Merkle tree.
+func (layout Layout) numLevels() int {
+ return len(layout.levelOffset)
+}
+
+// rootLevel returns the level of the root hash.
+func (layout Layout) rootLevel() int {
+ return layout.numLevels() - 1
+}
+
+// digestOffset finds the offset of a digest from the beginning of the tree.
+// The target digest is at level of the tree, with index from the beginning of
+// the current level.
+func (layout Layout) digestOffset(level int, index int64) int64 {
+ return layout.levelOffset[level] + index*layout.digestSize
+}
+
+// blockOffset finds the offset of a block from the beginning of the tree. The
+// target block is at level of the tree, with index from the beginning of the
+// current level.
+func (layout Layout) blockOffset(level int, index int64) int64 {
+ return layout.levelOffset[level] + index*layout.blockSize
}
// Generate constructs a Merkle tree for the contents of data. The output is
@@ -78,21 +108,21 @@ func MakeSize(dataSize int64) Size {
// it has been written. That is, treeWriter and treeReader should point to the
// same underlying data but have separate cursors.
func Generate(data io.Reader, dataSize int64, treeReader io.Reader, treeWriter io.Writer) ([]byte, error) {
- size := MakeSize(dataSize)
+ layout := InitLayout(dataSize)
- numBlocks := (dataSize + size.blockSize - 1) / size.blockSize
+ numBlocks := (dataSize + layout.blockSize - 1) / layout.blockSize
var root []byte
- for level := 0; level < len(size.levelStart); level++ {
+ for level := 0; level < layout.numLevels(); level++ {
for i := int64(0); i < numBlocks; i++ {
- buf := make([]byte, size.blockSize)
+ buf := make([]byte, layout.blockSize)
var (
n int
err error
)
if level == 0 {
- // Read data block from the target file since level 0 is directly above
- // the raw data block.
+ // Read data block from the target file since level 0 includes hashes
+ // of blocks in the input data.
n, err = data.Read(buf)
} else {
// Read data block from the tree file since levels higher than 0 are
@@ -112,7 +142,7 @@ func Generate(data io.Reader, dataSize int64, treeReader io.Reader, treeWriter i
// Hash the bytes in buf.
digest := sha256.Sum256(buf)
- if level == len(size.levelStart)-1 {
+ if level == layout.rootLevel() {
root = digest[:]
}
@@ -121,15 +151,164 @@ func Generate(data io.Reader, dataSize int64, treeReader io.Reader, treeWriter i
return nil, err
}
}
- // If the genereated digests do not round up to a block, zero-padding the
+ // If the generated digests do not round up to a block, zero-padding the
// remaining of the last block. But no need to do so for root.
- if level != len(size.levelStart)-1 && numBlocks%size.hashesPerBlock != 0 {
- zeroBuf := make([]byte, size.blockSize-(numBlocks%size.hashesPerBlock)*size.digestSize)
+ 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 {
return nil, err
}
}
- numBlocks = (numBlocks + size.hashesPerBlock - 1) / size.hashesPerBlock
+ numBlocks = (numBlocks + layout.hashesPerBlock() - 1) / layout.hashesPerBlock()
}
return root, nil
}
+
+// 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.
+// 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) error {
+ if readSize <= 0 {
+ return fmt.Errorf("Unexpected read size: %d", readSize)
+ }
+ layout := InitLayout(int64(dataSize))
+
+ // Calculate the index of blocks that includes the target range in input
+ // data.
+ firstDataBlock := readOffset / layout.blockSize
+ lastDataBlock := (readOffset + readSize - 1) / layout.blockSize
+
+ // Store the current offset, so we can set it back once verification
+ // finishes.
+ origOffset, err := data.Seek(0, io.SeekCurrent)
+ if err != nil {
+ return fmt.Errorf("Find current data offset failed: %v", err)
+ }
+ defer data.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 fmt.Errorf("Seek to datablock start failed: %v", err)
+ }
+
+ buf := make([]byte, layout.blockSize)
+ var readErr error
+ bytesRead := 0
+ for i := firstDataBlock; i <= lastDataBlock; i++ {
+ // Read a block that includes all or part of target range in
+ // input data.
+ bytesRead, readErr = data.Read(buf)
+ // If at the end of input data and all previous blocks are
+ // verified, return the verified input data and EOF.
+ if readErr == io.EOF && bytesRead == 0 {
+ break
+ }
+ if readErr != nil && readErr != io.EOF {
+ return fmt.Errorf("Read from data failed: %v", err)
+ }
+ // If this is the end of file, zero the remaining bytes in buf,
+ // otherwise they are still from the previous block.
+ // TODO(b/162908070): Investigate possible issues with zero
+ // padding the data.
+ if bytesRead < len(buf) {
+ for j := bytesRead; j < len(buf); j++ {
+ buf[j] = 0
+ }
+ }
+ if err := verifyBlock(tree, layout, buf, i, expectedRoot); err != nil {
+ return 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
+ }
+ // 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
+ }
+ // If the provided size exceeds the end of input data, we should
+ // only copy the parts in buf that's part of input data.
+ if startOff > int64(bytesRead) {
+ startOff = int64(bytesRead)
+ }
+ if endOff > int64(bytesRead) {
+ endOff = int64(bytesRead)
+ }
+ w.Write(buf[startOff:endOff])
+
+ }
+ return readErr
+}
+
+// verifyBlock verifies a block against tree. index is the number of block 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 {
+ if len(dataBlock) != int(layout.blockSize) {
+ return fmt.Errorf("incorrect block size")
+ }
+
+ expectedDigest := make([]byte, layout.digestSize)
+ treeBlock := make([]byte, layout.blockSize)
+ var digest []byte
+ for level := 0; level < layout.numLevels(); level++ {
+ // Calculate hash.
+ if level == 0 {
+ digestArray := sha256.Sum256(dataBlock)
+ digest = digestArray[:]
+ } else {
+ // Read a block in previous level that contains the
+ // hash we just generated, and generate a next level
+ // hash from it.
+ if _, err := tree.Seek(layout.blockOffset(level-1, blockIndex), io.SeekStart); err != nil {
+ return err
+ }
+ if _, err := tree.Read(treeBlock); err != nil {
+ return err
+ }
+ digestArray := sha256.Sum256(treeBlock)
+ digest = digestArray[:]
+ }
+
+ // Move to stored hash for the current block, read the digest
+ // and store in expectedDigest.
+ if _, err := tree.Seek(layout.digestOffset(level, blockIndex), io.SeekStart); err != nil {
+ return err
+ }
+ if _, err := tree.Read(expectedDigest); err != nil {
+ return err
+ }
+
+ 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
+ }
+ 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
+}
diff --git a/pkg/merkletree/merkletree_test.go b/pkg/merkletree/merkletree_test.go
index 7344db0b6..911f61df9 100644
--- a/pkg/merkletree/merkletree_test.go
+++ b/pkg/merkletree/merkletree_test.go
@@ -17,45 +17,48 @@ package merkletree
import (
"bytes"
"fmt"
+ "io"
+ "math/rand"
"testing"
+ "time"
"gvisor.dev/gvisor/pkg/usermem"
)
-func TestSize(t *testing.T) {
+func TestLayout(t *testing.T) {
testCases := []struct {
- dataSize int64
- expectedLevelStart []int64
+ dataSize int64
+ expectedLevelOffset []int64
}{
{
- dataSize: 100,
- expectedLevelStart: []int64{0},
+ dataSize: 100,
+ expectedLevelOffset: []int64{0},
},
{
- dataSize: 1000000,
- expectedLevelStart: []int64{0, 2, 3},
+ dataSize: 1000000,
+ expectedLevelOffset: []int64{0, 2 * usermem.PageSize, 3 * usermem.PageSize},
},
{
- dataSize: 4096 * int64(usermem.PageSize),
- expectedLevelStart: []int64{0, 32, 33},
+ dataSize: 4096 * int64(usermem.PageSize),
+ expectedLevelOffset: []int64{0, 32 * usermem.PageSize, 33 * usermem.PageSize},
},
}
for _, tc := range testCases {
t.Run(fmt.Sprintf("%d", tc.dataSize), func(t *testing.T) {
- s := MakeSize(tc.dataSize)
- if s.blockSize != int64(usermem.PageSize) {
- t.Errorf("got blockSize %d, want %d", s.blockSize, usermem.PageSize)
+ p := InitLayout(tc.dataSize)
+ if p.blockSize != int64(usermem.PageSize) {
+ t.Errorf("got blockSize %d, want %d", p.blockSize, usermem.PageSize)
}
- if s.digestSize != sha256DigestSize {
- t.Errorf("got digestSize %d, want %d", s.digestSize, sha256DigestSize)
+ if p.digestSize != sha256DigestSize {
+ t.Errorf("got digestSize %d, want %d", p.digestSize, sha256DigestSize)
}
- if len(s.levelStart) != len(tc.expectedLevelStart) {
- t.Errorf("got levels %d, want %d", len(s.levelStart), len(tc.expectedLevelStart))
+ if p.numLevels() != len(tc.expectedLevelOffset) {
+ t.Errorf("got levels %d, want %d", p.numLevels(), len(tc.expectedLevelOffset))
}
- for i := 0; i < len(s.levelStart) && i < len(tc.expectedLevelStart); i++ {
- if s.levelStart[i] != tc.expectedLevelStart[i] {
- t.Errorf("got levelStart[%d] %d, want %d", i, s.levelStart[i], tc.expectedLevelStart[i])
+ for i := 0; i < p.numLevels() && i < len(tc.expectedLevelOffset); i++ {
+ if p.levelOffset[i] != tc.expectedLevelOffset[i] {
+ t.Errorf("got levelStart[%d] %d, want %d", i, p.levelOffset[i], tc.expectedLevelOffset[i])
}
}
})
@@ -66,57 +69,285 @@ func TestGenerate(t *testing.T) {
// The input data has size dataSize. It starts with the data in startWith,
// and all other bytes are zeroes.
testCases := []struct {
- dataSize int
- startWith []byte
+ data []byte
expectedRoot []byte
}{
{
- dataSize: usermem.PageSize,
- startWith: nil,
+ data: bytes.Repeat([]byte{0}, usermem.PageSize),
expectedRoot: []byte{173, 127, 172, 178, 88, 111, 198, 233, 102, 192, 4, 215, 209, 209, 107, 2, 79, 88, 5, 255, 124, 180, 124, 122, 133, 218, 189, 139, 72, 137, 44, 167},
},
{
- dataSize: 128*usermem.PageSize + 1,
- startWith: nil,
+ data: bytes.Repeat([]byte{0}, 128*usermem.PageSize+1),
expectedRoot: []byte{62, 93, 40, 92, 161, 241, 30, 223, 202, 99, 39, 2, 132, 113, 240, 139, 117, 99, 79, 243, 54, 18, 100, 184, 141, 121, 238, 46, 149, 202, 203, 132},
},
{
- dataSize: 1,
- startWith: []byte{'a'},
+ data: []byte{'a'},
expectedRoot: []byte{52, 75, 204, 142, 172, 129, 37, 14, 145, 137, 103, 203, 11, 162, 209, 205, 30, 169, 213, 72, 20, 28, 243, 24, 242, 2, 92, 43, 169, 59, 110, 210},
},
{
- dataSize: 1,
- startWith: []byte{'1'},
- expectedRoot: []byte{74, 35, 103, 179, 176, 149, 254, 112, 42, 65, 104, 66, 119, 56, 133, 124, 228, 15, 65, 161, 150, 0, 117, 174, 242, 34, 115, 115, 218, 37, 3, 105},
+ data: bytes.Repeat([]byte{'a'}, usermem.PageSize),
+ expectedRoot: []byte{201, 62, 238, 45, 13, 176, 47, 16, 172, 199, 70, 13, 149, 118, 225, 34, 220, 248, 205, 83, 196, 191, 141, 252, 174, 27, 62, 116, 235, 207, 255, 90},
},
}
for _, tc := range testCases {
- t.Run(fmt.Sprintf("%d", tc.dataSize), func(t *testing.T) {
- var (
- data bytes.Buffer
- tree bytes.Buffer
- )
+ t.Run(fmt.Sprintf("%d:%v", len(tc.data), tc.data[0]), func(t *testing.T) {
+ var tree bytes.Buffer
- startSize := len(tc.startWith)
- _, err := data.Write(tc.startWith)
+ root, err := Generate(bytes.NewBuffer(tc.data), int64(len(tc.data)), &tree, &tree)
if err != nil {
- t.Fatalf("Failed to write to data: %v", err)
+ t.Fatalf("Generate failed: %v", err)
}
- _, err = data.Write(make([]byte, tc.dataSize-startSize))
- if err != nil {
- t.Fatalf("Failed to write to data: %v", err)
+
+ if !bytes.Equal(root, tc.expectedRoot) {
+ t.Errorf("Unexpected root")
}
+ })
+ }
+}
+
+// bytesReadWriter is used to read from/write to/seek in a byte array. Unlike
+// bytes.Buffer, it keeps the whole buffer during read so that it can be reused.
+type bytesReadWriter struct {
+ // bytes contains the underlying byte array.
+ bytes []byte
+ // readPos is the currently location for Read. Write always appends to
+ // the end of the array.
+ readPos int
+}
+
+func (brw *bytesReadWriter) Write(p []byte) (int, error) {
+ brw.bytes = append(brw.bytes, p...)
+ return len(p), nil
+}
+
+func (brw *bytesReadWriter) Read(p []byte) (int, error) {
+ if brw.readPos >= len(brw.bytes) {
+ return 0, io.EOF
+ }
+ bytesRead := copy(p, brw.bytes[brw.readPos:])
+ brw.readPos += bytesRead
+ if bytesRead < len(p) {
+ return bytesRead, io.EOF
+ }
+ return bytesRead, nil
+}
+
+func (brw *bytesReadWriter) Seek(offset int64, whence int) (int64, error) {
+ off := offset
+ if whence == io.SeekCurrent {
+ off += int64(brw.readPos)
+ }
+ if whence == io.SeekEnd {
+ off += int64(len(brw.bytes))
+ }
+ if off < 0 {
+ panic("seek with negative offset")
+ }
+ if off >= int64(len(brw.bytes)) {
+ return 0, io.EOF
+ }
+ brw.readPos = int(off)
+ return off, nil
+}
+
+func TestVerify(t *testing.T) {
+ // The input data has size dataSize. The portion to be verified ranges from
+ // verifyStart with verifySize. A bit is flipped in outOfRangeByteIndex to
+ // confirm that modifications outside the verification range does not cause
+ // issue. And a bit is flipped in modifyByte to confirm that
+ // modifications in the verification range is caught during verification.
+ testCases := []struct {
+ dataSize int64
+ verifyStart int64
+ verifySize int64
+ // A byte in input data is modified during the test. If the
+ // modified byte falls in verification range, Verify should
+ // fail, otherwise Verify should still succeed.
+ modifyByte int64
+ shouldSucceed bool
+ }{
+ // Verify range start outside the data range should fail.
+ {
+ dataSize: usermem.PageSize,
+ verifyStart: usermem.PageSize,
+ verifySize: 1,
+ modifyByte: 0,
+ shouldSucceed: false,
+ },
+ // Verifying range is valid if it starts inside data and ends
+ // outside data range, in that case start to the end of data is
+ // verified.
+ {
+ dataSize: usermem.PageSize,
+ verifyStart: 0,
+ verifySize: 2 * usermem.PageSize,
+ modifyByte: 0,
+ shouldSucceed: false,
+ },
+ // Invalid verify range (negative size) should fail.
+ {
+ dataSize: usermem.PageSize,
+ verifyStart: 1,
+ verifySize: -1,
+ modifyByte: 0,
+ shouldSucceed: false,
+ },
+ // Invalid verify range (0 size) should fail.
+ {
+ dataSize: usermem.PageSize,
+ verifyStart: 0,
+ verifySize: 0,
+ modifyByte: 0,
+ shouldSucceed: false,
+ },
+ // The test cases below use a block-aligned verify range.
+ // Modifying a byte in the verified range should cause verify
+ // to fail.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4 * usermem.PageSize,
+ verifySize: usermem.PageSize,
+ modifyByte: 4 * usermem.PageSize,
+ shouldSucceed: false,
+ },
+ // Modifying a byte before the verified range should not cause
+ // verify to fail.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4 * usermem.PageSize,
+ verifySize: usermem.PageSize,
+ modifyByte: 4*usermem.PageSize - 1,
+ shouldSucceed: true,
+ },
+ // Modifying a byte after the verified range should not cause
+ // verify to fail.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4 * usermem.PageSize,
+ verifySize: usermem.PageSize,
+ modifyByte: 5 * usermem.PageSize,
+ shouldSucceed: true,
+ },
+ // The tests below use a non-block-aligned verify range.
+ // Modifying a byte at strat of verify range should cause
+ // verify to fail.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4*usermem.PageSize + 123,
+ verifySize: 2 * usermem.PageSize,
+ modifyByte: 4*usermem.PageSize + 123,
+ shouldSucceed: false,
+ },
+ // Modifying a byte at the end of verify range should cause
+ // verify to fail.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4*usermem.PageSize + 123,
+ verifySize: 2 * usermem.PageSize,
+ modifyByte: 6*usermem.PageSize + 123,
+ shouldSucceed: false,
+ },
+ // Modifying a byte in the middle verified block should cause
+ // verify to fail.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4*usermem.PageSize + 123,
+ verifySize: 2 * usermem.PageSize,
+ modifyByte: 5*usermem.PageSize + 123,
+ shouldSucceed: false,
+ },
+ // Modifying a byte in the first block in the verified range
+ // should cause verify to fail, even the modified bit itself is
+ // out of verify range.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4*usermem.PageSize + 123,
+ verifySize: 2 * usermem.PageSize,
+ modifyByte: 4*usermem.PageSize + 122,
+ shouldSucceed: false,
+ },
+ // Modifying a byte in the last block in the verified range
+ // should cause verify to fail, even the modified bit itself is
+ // out of verify range.
+ {
+ dataSize: 8 * usermem.PageSize,
+ verifyStart: 4*usermem.PageSize + 123,
+ verifySize: 2 * usermem.PageSize,
+ modifyByte: 6*usermem.PageSize + 124,
+ shouldSucceed: false,
+ },
+ }
+
+ for _, tc := range testCases {
+ t.Run(fmt.Sprintf("%d", tc.modifyByte), func(t *testing.T) {
+ data := make([]byte, tc.dataSize)
+ // Generate random bytes in data.
+ rand.Read(data)
+ var tree bytesReadWriter
- root, err := Generate(&data, int64(tc.dataSize), &tree, &tree)
+ root, err := Generate(bytes.NewBuffer(data), int64(tc.dataSize), &tree, &tree)
if err != nil {
t.Fatalf("Generate failed: %v", err)
}
- if !bytes.Equal(root, tc.expectedRoot) {
- t.Errorf("Unexpected root")
+ // Flip a bit in data and checks Verify results.
+ var buf bytes.Buffer
+ data[tc.modifyByte] ^= 1
+ if tc.shouldSucceed {
+ if err := Verify(&buf, bytes.NewReader(data), &tree, tc.dataSize, tc.verifyStart, tc.verifySize, root); err != nil && err != io.EOF {
+ t.Errorf("Verification failed when expected to succeed: %v", err)
+ }
+ if int64(buf.Len()) != tc.verifySize || !bytes.Equal(data[tc.verifyStart:tc.verifyStart+tc.verifySize], buf.Bytes()) {
+ t.Errorf("Incorrect output from Verify")
+ }
+ } else {
+ if err := Verify(&buf, bytes.NewReader(data), &tree, tc.dataSize, tc.verifyStart, tc.verifySize, root); err == nil {
+ t.Errorf("Verification succeeded when expected to fail")
+ }
}
})
}
}
+
+func TestVerifyRandom(t *testing.T) {
+ rand.Seed(time.Now().UnixNano())
+ // Use a random dataSize. Minimum size 2 so that we can pick a random
+ // portion from it.
+ dataSize := rand.Int63n(200*usermem.PageSize) + 2
+ data := make([]byte, dataSize)
+ // Generate random bytes in data.
+ rand.Read(data)
+ var tree bytesReadWriter
+
+ root, err := Generate(bytes.NewBuffer(data), int64(dataSize), &tree, &tree)
+ if err != nil {
+ t.Fatalf("Generate failed: %v", err)
+ }
+
+ // Pick a random portion of data.
+ start := rand.Int63n(dataSize - 1)
+ size := rand.Int63n(dataSize) + 1
+
+ var buf bytes.Buffer
+ // Checks that the random portion of data from the original data is
+ // verified successfully.
+ if err := Verify(&buf, bytes.NewReader(data), &tree, dataSize, start, size, root); err != nil && err != io.EOF {
+ t.Errorf("Verification failed for correct data: %v", err)
+ }
+ if size > dataSize-start {
+ size = dataSize - start
+ }
+ if int64(buf.Len()) != size || !bytes.Equal(data[start:start+size], buf.Bytes()) {
+ t.Errorf("Incorrect output from Verify")
+ }
+
+ buf.Reset()
+ // Flip a random bit in randPortion, and check that verification fails.
+ randBytePos := rand.Int63n(size)
+ data[start+randBytePos] ^= 1
+
+ if err := Verify(&buf, bytes.NewReader(data), &tree, dataSize, start, size, root); err == nil {
+ t.Errorf("Verification succeeded for modified data")
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 00:44:09 +0000