Max string length

Plugin.cpp

@@ -45,7 +45,9 @@ bool addPassWithName(FunctionPassManager &FPM, StringRef &passName) {
 
 bool addPassWithName(ModulePassManager &MPM, StringRef &passName) {
   if (passName == "string-encryption") {
-    MPM.addPass(StringObfuscatorPass());
+    size_t maxSize = 0;
+    getEnvVar(EnvVarPrefix + "MAX_STRING_LENGTH").getAsInteger(10, maxSize);
+    MPM.addPass(StringObfuscatorPass{maxSize});
   } else {
     return false;
   }

README.md

@@ -55,6 +55,9 @@ Or you can run the string encryption pass with:
 
 Refer to the llvm::PassBuilder documentation for more information on each insertion point.
 
+You can limit the length of strings that are obfuscated with the `LLVM_OBF_MAX_STRING_LENGTH` environment variable. A 
+value of 0 (the default) means no limit.
+
 ### With opt
 
 [`opt`](https://llvm.org/docs/CommandGuide/opt.html) can be used to apply specific passes from LLRM-IR you

flattening/Flattening.cpp

@@ -17,7 +17,11 @@
 #include "llvm/Analysis/LazyValueInfo.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Passes/PassBuilder.h"
+#if LLVM_VERSION_MAJOR >= 22
+#include "llvm/Plugins/PassPlugin.h"
+#else
 #include "llvm/Passes/PassPlugin.h"
+#endif
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/LowerSwitch.h"

split/SplitBasicBlocks.cpp

@@ -15,7 +15,11 @@
 #include "utils/Utils.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Passes/PassBuilder.h"
+#if LLVM_VERSION_MAJOR >= 22
+#include "llvm/Plugins/PassPlugin.h"
+#else
 #include "llvm/Passes/PassPlugin.h"
+#endif
 
 #include "utils/CryptoUtils.h"
 

string/StringObfuscation.cpp

@@ -7,7 +7,11 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Passes/PassBuilder.h"
+#if LLVM_VERSION_MAJOR >= 22
+#include "llvm/Plugins/PassPlugin.h"
+#else
 #include "llvm/Passes/PassPlugin.h"
+#endif
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
@@ -28,14 +32,8 @@ ConstantDataArray *StringObfuscatorPass::encodeStringDataArray(LLVMContext &ctx,
                                                                const char *str,
                                                                size_t size,
                                                                uint8_t key) {
-  // Check this is a valid string (not containing zeros)
-  if (str[size - 1] == '\0') {
-    if (strnlen(str, size) != size - 1)
-      return nullptr;
-  } else {
-    if (strnlen(str, size) != size)
-      return nullptr;
-  }
+  if (this->maxSize != 0 && size > this->maxSize)
+    return nullptr;
 
   // Encode the data
   char *encodedStr = (char *)malloc(size);
@@ -87,17 +85,18 @@ void StringObfuscatorPass::encodeStructString(LLVMContext &ctx,
   }
 }
 
-StringObfuscatorPass::StringObfuscatorPass() {}
+StringObfuscatorPass::StringObfuscatorPass(size_t maxSize) : maxSize{maxSize} {}
 
 bool StringObfuscatorPass::encodeAllStrings(Module &M) {
   auto &ctx = M.getContext();
 
   // For each global variable
   for (GlobalVariable &gv : M.globals()) {
-    if (!gv.isConstant()                         // constant
-        || !gv.hasInitializer()                  // unitialized
-        || gv.hasExternalLinkage()               // external
-        || gv.getSection() == "llvm.metadata") { // Intrinsic Global Variables
+    if (!gv.isConstant()                           // constant
+        || !gv.hasInitializer()                    // unitialized
+        || gv.hasExternalLinkage()                 // external
+        || gv.getAlign().valueOrOne().value() != 1 // align == 1
+        || gv.getSection() == "llvm.metadata") {   // Intrinsic Global Variables
       //|| gv.getSection().find("__objc_methname") != string::npos) { // TODO :
       // is this necessary ?
       continue;
@@ -109,7 +108,7 @@ bool StringObfuscatorPass::encodeAllStrings(Module &M) {
     // Encode the value and update the variable
     if (isa<ConstantDataArray>(initializer)) { // Global variable
       auto array = cast<ConstantDataArray>(initializer);
-      if (array->isCString()) {
+      if (array->isString()) {
         encodeGlobalString(ctx, &gv, array);
       }
     } else if (isa<ConstantStruct>(initializer)) { // Variable in a struct
@@ -118,7 +117,7 @@ bool StringObfuscatorPass::encodeAllStrings(Module &M) {
         auto operand = cs->getOperand(i);
         if (isa<ConstantDataArray>(operand)) {
           auto array = cast<ConstantDataArray>(operand);
-          if (array->isCString()) {
+          if (array->isString()) {
             encodeStructString(ctx, &gv, cs, array, i);
           }
         }

string/StringObfuscation.h

@@ -30,11 +30,13 @@ struct GlobalStringVariable {
   }
 };
 
+
 namespace llvm {
 struct StringObfuscatorPass : public PassInfoMixin<StringObfuscatorPass> {
   std::vector<GlobalStringVariable> globalStrings;
+  size_t maxSize;
 
-  StringObfuscatorPass();
+  StringObfuscatorPass(size_t maxSize);
   ConstantDataArray *encodeStringDataArray(LLVMContext &ctx, const char *str,
                                            size_t size, uint8_t key);
   void encodeStructString(LLVMContext &ctx, GlobalVariable *gv,