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MosisService/docs/SANDBOX_MILESTONE_8.md

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# Milestone 8: SQLite Database
**Status**: Complete ✅
**Goal**: Per-app SQLite with injection prevention.
---
## Overview
This milestone implements a sandboxed SQLite database for Lua apps:
- Per-app isolated database files
- SQL injection prevention via prepared statements
- SQLite authorizer to block dangerous operations
- Database size limits
### Key Deliverables
1. **DatabaseManager class** - SQLite wrapper with security
2. **Lua db API** - open, execute, query, close
3. **SQL authorizer** - Block ATTACH, DETACH, dangerous PRAGMAs
4. **Prepared statements** - Parameterized queries only
---
## File Structure
```
src/main/cpp/sandbox/
├── database_manager.h # NEW - DatabaseManager header
└── database_manager.cpp # NEW - DatabaseManager implementation
```
---
## Implementation Details
### 1. Database Path Mapping
```
Database Name → Physical Path
─────────────────────────────────────────────────────────────
"mydata" → <app_root>/db/mydata.db
"cache" → <app_root>/db/cache.db
```
For testing, `app_root` is configurable (e.g., `./test_apps/<app_id>/`).
### 2. DatabaseManager Class
```cpp
// database_manager.h
#pragma once
#include <string>
#include <vector>
#include <variant>
#include <optional>
#include <memory>
struct sqlite3;
struct lua_State;
namespace mosis {
// SQL value types
using SqlValue = std::variant<std::nullptr_t, int64_t, double, std::string, std::vector<uint8_t>>;
using SqlRow = std::vector<SqlValue>;
using SqlResult = std::vector<SqlRow>;
struct DatabaseLimits {
size_t max_database_size = 50 * 1024 * 1024; // 50 MB per database
int max_databases_per_app = 5; // Max open databases
int max_query_time_ms = 5000; // 5 second query timeout
int max_result_rows = 10000; // Max rows returned
};
class DatabaseHandle;
class DatabaseManager {
public:
DatabaseManager(const std::string& app_id,
const std::string& app_root,
const DatabaseLimits& limits = DatabaseLimits{});
~DatabaseManager();
// Database operations
std::shared_ptr<DatabaseHandle> Open(const std::string& name, std::string& error);
void CloseAll();
// Stats
size_t GetOpenDatabaseCount() const;
private:
std::string m_app_id;
std::string m_app_root;
DatabaseLimits m_limits;
std::vector<std::shared_ptr<DatabaseHandle>> m_databases;
std::string ResolvePath(const std::string& name);
bool ValidateName(const std::string& name, std::string& error);
};
class DatabaseHandle {
public:
DatabaseHandle(sqlite3* db, const std::string& path, const DatabaseLimits& limits);
~DatabaseHandle();
// Execute (INSERT, UPDATE, DELETE, CREATE, etc.)
bool Execute(const std::string& sql, const std::vector<SqlValue>& params, std::string& error);
// Query (SELECT)
std::optional<SqlResult> Query(const std::string& sql, const std::vector<SqlValue>& params,
std::string& error);
// Get last insert rowid
int64_t GetLastInsertRowId() const;
// Get affected rows
int GetChanges() const;
bool IsOpen() const { return m_db != nullptr; }
void Close();
private:
sqlite3* m_db;
std::string m_path;
DatabaseLimits m_limits;
static int Authorizer(void* user_data, int action, const char* arg1,
const char* arg2, const char* arg3, const char* arg4);
};
// Register db.* APIs as globals
void RegisterDatabaseAPI(lua_State* L, DatabaseManager* manager);
} // namespace mosis
```
### 3. SQLite Authorizer Rules
Block dangerous operations:
| Action | Decision | Reason |
|--------|----------|--------|
| ATTACH | DENY | Prevents accessing other databases |
| DETACH | DENY | Prevents detaching |
| PRAGMA (most) | DENY | Many PRAGMAs are dangerous |
| PRAGMA table_info | ALLOW | Safe introspection |
| PRAGMA index_list | ALLOW | Safe introspection |
| PRAGMA foreign_keys | ALLOW | Safe setting |
| Function (load_extension) | DENY | Prevents loading native code |
### 4. Lua API
```lua
-- Open database (creates if not exists)
local db, err = database.open("mydata")
if not db then
print("Error: " .. err)
return
end
-- Create table
local ok, err = db:execute([[
CREATE TABLE IF NOT EXISTS items (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL,
price REAL
)
]])
-- Insert with parameters (prevents SQL injection)
db:execute("INSERT INTO items (name, price) VALUES (?, ?)", {"Widget", 19.99})
-- Query with parameters
local rows, err = db:query("SELECT * FROM items WHERE price > ?", {10.0})
if rows then
for _, row in ipairs(rows) do
print(row[1], row[2], row[3]) -- id, name, price
end
end
-- Get last insert ID
local id = db:lastInsertId()
-- Get affected rows
local changes = db:changes()
-- Close database
db:close()
```
### 5. Security Features
1. **Prepared Statements**: All queries use parameterized binding
2. **Authorizer**: Block dangerous SQL operations
3. **Path Sandboxing**: Database files only in app's db/ directory
4. **Size Limits**: Enforce max database size
5. **Query Timeout**: Prevent long-running queries
6. **Result Limits**: Cap number of returned rows
---
## Test Cases
### Test 1: Create and Query Tables
```cpp
bool Test_DatabaseCreatesTables(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
auto db = manager.Open("test", err);
EXPECT_TRUE(db != nullptr);
// Create table
EXPECT_TRUE(db->Execute(
"CREATE TABLE IF NOT EXISTS items (id INTEGER PRIMARY KEY, name TEXT)",
{}, err));
// Insert
EXPECT_TRUE(db->Execute(
"INSERT INTO items (name) VALUES (?)",
{std::string("Test Item")}, err));
// Query
auto rows = db->Query("SELECT * FROM items", {}, err);
EXPECT_TRUE(rows.has_value());
EXPECT_TRUE(rows->size() == 1);
db->Close();
manager.CloseAll();
// Cleanup
std::filesystem::remove_all(test_root);
return true;
}
```
### Test 2: Prepared Statements Prevent Injection
```cpp
bool Test_DatabasePreparedStatements(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
auto db = manager.Open("test", err);
EXPECT_TRUE(db != nullptr);
db->Execute("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)", {}, err);
db->Execute("INSERT INTO users (name) VALUES (?)", {std::string("Alice")}, err);
// Attempt SQL injection via parameter - should be safely escaped
std::string malicious = "'; DROP TABLE users; --";
auto rows = db->Query("SELECT * FROM users WHERE name = ?", {malicious}, err);
// Query should succeed (finding nothing) and table should still exist
EXPECT_TRUE(rows.has_value());
EXPECT_TRUE(rows->size() == 0);
// Table should still exist
auto check = db->Query("SELECT * FROM users", {}, err);
EXPECT_TRUE(check.has_value());
EXPECT_TRUE(check->size() == 1);
db->Close();
std::filesystem::remove_all(test_root);
return true;
}
```
### Test 3: Blocks ATTACH
```cpp
bool Test_DatabaseBlocksAttach(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
auto db = manager.Open("test", err);
EXPECT_TRUE(db != nullptr);
// Try to attach another database - should fail
EXPECT_FALSE(db->Execute("ATTACH DATABASE '/etc/passwd' AS evil", {}, err));
EXPECT_TRUE(err.find("authorized") != std::string::npos ||
err.find("denied") != std::string::npos);
db->Close();
std::filesystem::remove_all(test_root);
return true;
}
```
### Test 4: Blocks Dangerous PRAGMA
```cpp
bool Test_DatabaseBlocksDangerousPragma(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
auto db = manager.Open("test", err);
EXPECT_TRUE(db != nullptr);
// Try dangerous PRAGMAs - should fail
EXPECT_FALSE(db->Execute("PRAGMA journal_mode = OFF", {}, err));
EXPECT_FALSE(db->Execute("PRAGMA synchronous = OFF", {}, err));
// Safe PRAGMAs should work
auto rows = db->Query("PRAGMA table_info(sqlite_master)", {}, err);
EXPECT_TRUE(rows.has_value());
db->Close();
std::filesystem::remove_all(test_root);
return true;
}
```
### Test 5: Multiple Databases
```cpp
bool Test_DatabaseMultiple(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
auto db1 = manager.Open("db1", err);
auto db2 = manager.Open("db2", err);
EXPECT_TRUE(db1 != nullptr);
EXPECT_TRUE(db2 != nullptr);
EXPECT_TRUE(manager.GetOpenDatabaseCount() == 2);
// They should be independent
db1->Execute("CREATE TABLE t1 (x INTEGER)", {}, err);
db2->Execute("CREATE TABLE t2 (y INTEGER)", {}, err);
// t1 shouldn't exist in db2
auto rows = db2->Query("SELECT * FROM t1", {}, err);
EXPECT_FALSE(rows.has_value()); // Should fail - table doesn't exist
manager.CloseAll();
std::filesystem::remove_all(test_root);
return true;
}
```
### Test 6: Lua Integration
```cpp
bool Test_DatabaseLuaIntegration(std::string& error_msg) {
SandboxContext ctx = TestContext();
LuaSandbox sandbox(ctx);
std::string test_root = "test_db_lua";
mosis::DatabaseManager manager("test.app", test_root);
mosis::RegisterDatabaseAPI(sandbox.GetState(), &manager);
std::string script = R"(
local db, err = database.open("test")
assert(db, "failed to open: " .. (err or ""))
-- Create table
local ok, err = db:execute("CREATE TABLE items (id INTEGER PRIMARY KEY, name TEXT)")
assert(ok, "create failed: " .. (err or ""))
-- Insert
ok, err = db:execute("INSERT INTO items (name) VALUES (?)", {"Test"})
assert(ok, "insert failed: " .. (err or ""))
-- Query
local rows, err = db:query("SELECT * FROM items")
assert(rows, "query failed: " .. (err or ""))
assert(#rows == 1, "expected 1 row")
db:close()
)";
bool ok = sandbox.LoadString(script, "db_test");
manager.CloseAll();
std::filesystem::remove_all(test_root);
if (!ok) {
error_msg = "Lua test failed: " + sandbox.GetLastError();
return false;
}
return true;
}
```
### Test 7: Invalid Database Names
```cpp
bool Test_DatabaseInvalidNames(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
// Path traversal
auto db1 = manager.Open("../evil", err);
EXPECT_TRUE(db1 == nullptr);
// Absolute path
auto db2 = manager.Open("/etc/passwd", err);
EXPECT_TRUE(db2 == nullptr);
// Special characters
auto db3 = manager.Open("test;drop", err);
EXPECT_TRUE(db3 == nullptr);
std::filesystem::remove_all(test_root);
return true;
}
```
### Test 8: Last Insert ID and Changes
```cpp
bool Test_DatabaseLastInsertAndChanges(std::string& error_msg) {
std::string test_root = "test_db_app";
mosis::DatabaseManager manager("test.app", test_root);
std::string err;
auto db = manager.Open("test", err);
EXPECT_TRUE(db != nullptr);
db->Execute("CREATE TABLE items (id INTEGER PRIMARY KEY, name TEXT)", {}, err);
db->Execute("INSERT INTO items (name) VALUES (?)", {std::string("Item 1")}, err);
EXPECT_TRUE(db->GetLastInsertRowId() == 1);
EXPECT_TRUE(db->GetChanges() == 1);
db->Execute("INSERT INTO items (name) VALUES (?)", {std::string("Item 2")}, err);
EXPECT_TRUE(db->GetLastInsertRowId() == 2);
db->Execute("UPDATE items SET name = ?", {std::string("Updated")}, err);
EXPECT_TRUE(db->GetChanges() == 2); // Updated 2 rows
db->Close();
std::filesystem::remove_all(test_root);
return true;
}
```
---
## Acceptance Criteria
All tests must pass:
- [x] `Test_DatabaseCreatesTables` - Basic create/insert/query
- [x] `Test_DatabasePreparedStatements` - SQL injection prevention
- [x] `Test_DatabaseBlocksAttach` - ATTACH blocked
- [x] `Test_DatabaseBlocksDangerousPragma` - Dangerous PRAGMAs blocked
- [x] `Test_DatabaseMultiple` - Multiple isolated databases
- [x] `Test_DatabaseLuaIntegration` - Lua API works
- [x] `Test_DatabaseInvalidNames` - Path validation
- [x] `Test_DatabaseLastInsertAndChanges` - Metadata functions
---
## Dependencies
- Milestone 1 (LuaSandbox)
- SQLite3 library (add to vcpkg.json)
---
## Next Steps
After Milestone 8 passes:
1. Milestone 9: Network - HTTP
2. Milestone 10: Network - WebSocket