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trie: reject deletions when verifying range proofs #23960

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Nov 23, 2021
Merged

trie: reject deletions when verifying range proofs #23960

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7 changes: 6 additions & 1 deletion trie/proof.go
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Original file line number Diff line number Diff line change
Expand Up @@ -472,12 +472,17 @@ func VerifyRangeProof(rootHash common.Hash, firstKey []byte, lastKey []byte, key
if len(keys) != len(values) {
return false, fmt.Errorf("inconsistent proof data, keys: %d, values: %d", len(keys), len(values))
}
// Ensure the received batch is monotonic increasing.
// Ensure the received batch is monotonic increasing and contains no deletions
for i := 0; i < len(keys)-1; i++ {
if bytes.Compare(keys[i], keys[i+1]) >= 0 {
return false, errors.New("range is not monotonically increasing")
}
}
for _, value := range values {
if len(value) == 0 {
return false, errors.New("range contains deletion")
}
}
Comment on lines +475 to +485
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len(keys) == len(values), so you could use the same loop, with a slight modification

Suggested change
// Ensure the received batch is monotonic increasing and contains no deletions
for i := 0; i < len(keys)-1; i++ {
if bytes.Compare(keys[i], keys[i+1]) >= 0 {
return false, errors.New("range is not monotonically increasing")
}
}
for _, value := range values {
if len(value) == 0 {
return false, errors.New("range contains deletion")
}
}
// Ensure the received batch is monotonic increasing and contains no deletions
for i := 0; i < len(keys); i++ {
if i > 0 && bytes.Compare(keys[i-1], keys[i]) >= 0 {
return false, errors.New("range is not monotonically increasing")
}
if len(values[i]) == 0 {
return false, errors.New("range contains deletion")
}
}

Feel free to ignore

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👍

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It did occur to me, but the off by one and extra clause check seemed wonky. The code is cleaner this way, we're not saving anything by optimizing out an extra addition per array item. Unless you guys feel very strongly, I'd leave it as is.

// Special case, there is no edge proof at all. The given range is expected
// to be the whole leaf-set in the trie.
if proof == nil {
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79 changes: 79 additions & 0 deletions trie/proof_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -813,6 +813,85 @@ func TestBloatedProof(t *testing.T) {
}
}

// TestEmptyValueRangeProof tests normal range proof with both edge proofs
// as the existent proof, but with an extra empty value included, which is a
// noop technically, but practically should be rejected.
func TestEmptyValueRangeProof(t *testing.T) {
trie, values := randomTrie(512)
var entries entrySlice
for _, kv := range values {
entries = append(entries, kv)
}
sort.Sort(entries)

// Create a new entry with a slightly modified key
mid := len(entries) / 2
key := common.CopyBytes(entries[mid-1].k)
for n := len(key) - 1; n >= 0; n-- {
if key[n] < 0xff {
key[n]++
break
}
}
noop := &kv{key, []byte{}, false}
entries = append(append(append([]*kv{}, entries[:mid]...), noop), entries[mid:]...)

start, end := 1, len(entries)-1

proof := memorydb.New()
if err := trie.Prove(entries[start].k, 0, proof); err != nil {
t.Fatalf("Failed to prove the first node %v", err)
}
if err := trie.Prove(entries[end-1].k, 0, proof); err != nil {
t.Fatalf("Failed to prove the last node %v", err)
}
var keys [][]byte
var vals [][]byte
for i := start; i < end; i++ {
keys = append(keys, entries[i].k)
vals = append(vals, entries[i].v)
}
_, err := VerifyRangeProof(trie.Hash(), keys[0], keys[len(keys)-1], keys, vals, proof)
if err == nil {
t.Fatalf("Expected failure on noop entry")
}
}

// TestAllElementsEmptyValueRangeProof tests the range proof with all elements,
// but with an extra empty value included, which is a noop technically, but
// practically should be rejected.
func TestAllElementsEmptyValueRangeProof(t *testing.T) {
trie, values := randomTrie(512)
var entries entrySlice
for _, kv := range values {
entries = append(entries, kv)
}
sort.Sort(entries)

// Create a new entry with a slightly modified key
mid := len(entries) / 2
key := common.CopyBytes(entries[mid-1].k)
for n := len(key) - 1; n >= 0; n-- {
if key[n] < 0xff {
key[n]++
break
}
}
noop := &kv{key, []byte{}, false}
entries = append(append(append([]*kv{}, entries[:mid]...), noop), entries[mid:]...)

var keys [][]byte
var vals [][]byte
for i := 0; i < len(entries); i++ {
keys = append(keys, entries[i].k)
vals = append(vals, entries[i].v)
}
_, err := VerifyRangeProof(trie.Hash(), nil, nil, keys, vals, nil)
if err == nil {
t.Fatalf("Expected failure on noop entry")
}
}

// mutateByte changes one byte in b.
func mutateByte(b []byte) {
for r := mrand.Intn(len(b)); ; {
Expand Down