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FST: Refactoring to fix a read bug + verify all reads

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- Fixes a bug where corrupted data would be returned when reading files from unhashed sections with non-block aligned offset or size
- Added hash checks for all reads where possible. This means that FST now can automatically catch corruptions when they are encountered while reading from the volume
This commit is contained in:
Exzap
2024-11-13 06:29:23 +01:00
parent ca2e0a7c31
commit a5717e1b11
2 changed files with 301 additions and 116 deletions
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src/Cafe/Filesystem/FST/FST.cpp
+268 -111
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src/Cafe/Filesystem/FST/FST.h
+33 -5
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@@ -1,5 +1,6 @@
#pragma once
#include "Cemu/ncrypto/ncrypto.h"
#include "openssl/evp.h"
struct FSTFileHandle
{
@@ -45,6 +46,7 @@ public:
~FSTVolume();
uint32 GetFileCount() const;
bool HasCorruption() const { return m_detectedCorruption; }
bool OpenFile(std::string_view path, FSTFileHandle& fileHandleOut, bool openOnlyFiles = false);
@@ -86,15 +88,25 @@ private:
enum class ClusterHashMode : uint8
{
RAW = 0, // raw data + encryption, no hashing?
RAW2 = 1, // raw data + encryption, with hash stored in tmd?
RAW_STREAM = 1, // raw data + encryption, with hash stored in tmd?
HASH_INTERLEAVED = 2, // hashes + raw interleaved in 0x10000 blocks (0x400 bytes of hashes at the beginning, followed by 0xFC00 bytes of data)
};
struct FSTCluster
{
FSTCluster() : singleHashCtx(nullptr, &EVP_MD_CTX_free) {}
uint32 offset;
uint32 size;
ClusterHashMode hashMode;
// extra data if TMD is available
bool hasContentHash;
uint8 contentHash32[32];
bool contentHashIsSHA1; // if true then it's SHA1 (with extra bytes zeroed out), otherwise it's SHA256
uint64 contentSize; // size of the content (in blocks)
// hash context for single hash mode (content hash must be available)
std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)> singleHashCtx; // unique_ptr to make this move-only
uint32 singleHashNumBlocksHashed{0};
};
struct FSTEntry
@@ -164,17 +176,30 @@ private:
bool m_sourceIsOwned{};
uint32 m_sectorSize{}; // for cluster offsets
uint32 m_offsetFactor{}; // for file offsets
bool m_hashIsDisabled{}; // disables hash verification (for all clusters of this volume?)
std::vector<FSTCluster> m_cluster;
std::vector<FSTEntry> m_entries;
std::vector<char> m_nameStringTable;
NCrypto::AesKey m_partitionTitlekey;
bool m_detectedCorruption{false};
/* Cache for decrypted hashed blocks */
bool HashIsDisabled() const
{
return m_hashIsDisabled;
}
/* Cache for decrypted raw and hashed blocks */
std::unordered_map<uint64, struct FSTCachedRawBlock*> m_cacheDecryptedRawBlocks;
std::unordered_map<uint64, struct FSTCachedHashedBlock*> m_cacheDecryptedHashedBlocks;
uint64 m_cacheAccessCounter{};
void DetermineUnhashedBlockIV(uint32 clusterIndex, uint32 blockIndex, uint8 ivOut[16]);
struct FSTCachedRawBlock* GetDecryptedRawBlock(uint32 clusterIndex, uint32 blockIndex);
struct FSTCachedHashedBlock* GetDecryptedHashedBlock(uint32 clusterIndex, uint32 blockIndex);
void TrimCacheIfRequired(struct FSTCachedRawBlock** droppedRawBlock, struct FSTCachedHashedBlock** droppedHashedBlock);
/* File reading */
uint32 ReadFile_HashModeRaw(uint32 clusterIndex, FSTEntry& entry, uint32 readOffset, uint32 readSize, void* dataOut);
uint32 ReadFile_HashModeHashed(uint32 clusterIndex, FSTEntry& entry, uint32 readOffset, uint32 readSize, void* dataOut);
@@ -185,7 +210,10 @@ private:
/* +0x00 */ uint32be magic;
/* +0x04 */ uint32be offsetFactor;
/* +0x08 */ uint32be numCluster;
/* +0x0C */ uint32be ukn0C;
/* +0x0C */ uint8be hashIsDisabled;
/* +0x0D */ uint8be ukn0D;
/* +0x0E */ uint8be ukn0E;
/* +0x0F */ uint8be ukn0F;
/* +0x10 */ uint32be ukn10;
/* +0x14 */ uint32be ukn14;
/* +0x18 */ uint32be ukn18;
@@ -262,8 +290,8 @@ private:
static_assert(sizeof(FSTHeader_FileEntry) == 0x10);
static FSTVolume* OpenFST(FSTDataSource* dataSource, uint64 fstOffset, uint32 fstSize, NCrypto::AesKey* partitionTitleKey, ClusterHashMode fstHashMode);
static FSTVolume* OpenFST(std::unique_ptr<FSTDataSource> dataSource, uint64 fstOffset, uint32 fstSize, NCrypto::AesKey* partitionTitleKey, ClusterHashMode fstHashMode);
static FSTVolume* OpenFST(FSTDataSource* dataSource, uint64 fstOffset, uint32 fstSize, NCrypto::AesKey* partitionTitleKey, ClusterHashMode fstHashMode, NCrypto::TMDParser* optionalTMD);
static FSTVolume* OpenFST(std::unique_ptr<FSTDataSource> dataSource, uint64 fstOffset, uint32 fstSize, NCrypto::AesKey* partitionTitleKey, ClusterHashMode fstHashMode, NCrypto::TMDParser* optionalTMD);
static bool ProcessFST(FSTHeader_FileEntry* fileTable, uint32 numFileEntries, uint32 numCluster, std::vector<char>& nameStringTable, std::vector<FSTEntry>& fstEntries);
bool MatchFSTEntryName(FSTEntry& entry, std::string_view comparedName)