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-rw-r--r--llvm/tools/llvm-cfi-verify/CMakeLists.txt5
-rw-r--r--llvm/tools/llvm-cfi-verify/lib/CMakeLists.txt4
-rw-r--r--llvm/tools/llvm-cfi-verify/lib/FileAnalysis.h3
-rw-r--r--llvm/tools/llvm-cfi-verify/lib/GraphBuilder.cpp291
-rw-r--r--llvm/tools/llvm-cfi-verify/lib/GraphBuilder.h133
5 files changed, 431 insertions, 5 deletions
diff --git a/llvm/tools/llvm-cfi-verify/CMakeLists.txt b/llvm/tools/llvm-cfi-verify/CMakeLists.txt
index bf65cf7785c..ae203e53470 100644
--- a/llvm/tools/llvm-cfi-verify/CMakeLists.txt
+++ b/llvm/tools/llvm-cfi-verify/CMakeLists.txt
@@ -4,6 +4,7 @@ set(LLVM_LINK_COMPONENTS
AllTargetsDescs
AllTargetsDisassemblers
AllTargetsInfos
+ CFIVerify
MC
MCParser
Object
@@ -11,8 +12,6 @@ set(LLVM_LINK_COMPONENTS
)
add_llvm_tool(llvm-cfi-verify
- llvm-cfi-verify.cpp
- lib/FileAnalysis.cpp
- )
+ llvm-cfi-verify.cpp)
add_subdirectory(lib)
diff --git a/llvm/tools/llvm-cfi-verify/lib/CMakeLists.txt b/llvm/tools/llvm-cfi-verify/lib/CMakeLists.txt
index 814e30a234b..8cbbc79ceca 100644
--- a/llvm/tools/llvm-cfi-verify/lib/CMakeLists.txt
+++ b/llvm/tools/llvm-cfi-verify/lib/CMakeLists.txt
@@ -1,7 +1,9 @@
add_library(LLVMCFIVerify
STATIC
FileAnalysis.cpp
- FileAnalysis.h)
+ FileAnalysis.h
+ GraphBuilder.cpp
+ GraphBuilder.h)
llvm_update_compile_flags(LLVMCFIVerify)
llvm_map_components_to_libnames(libs
diff --git a/llvm/tools/llvm-cfi-verify/lib/FileAnalysis.h b/llvm/tools/llvm-cfi-verify/lib/FileAnalysis.h
index df1ad603b6c..3c24bcda75c 100644
--- a/llvm/tools/llvm-cfi-verify/lib/FileAnalysis.h
+++ b/llvm/tools/llvm-cfi-verify/lib/FileAnalysis.h
@@ -10,6 +10,7 @@
#ifndef LLVM_CFI_VERIFY_FILE_ANALYSIS_H
#define LLVM_CFI_VERIFY_FILE_ANALYSIS_H
+#include "llvm/ADT/DenseMap.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
@@ -161,7 +162,7 @@ private:
// Contains a mapping between a specific address, and a list of instructions
// that use this address as a branch target (including call instructions).
- std::unordered_map<uint64_t, std::vector<uint64_t>> StaticBranchTargetings;
+ DenseMap<uint64_t, std::vector<uint64_t>> StaticBranchTargetings;
// A list of addresses of indirect control flow instructions.
std::set<uint64_t> IndirectInstructions;
diff --git a/llvm/tools/llvm-cfi-verify/lib/GraphBuilder.cpp b/llvm/tools/llvm-cfi-verify/lib/GraphBuilder.cpp
new file mode 100644
index 00000000000..1121045780f
--- /dev/null
+++ b/llvm/tools/llvm-cfi-verify/lib/GraphBuilder.cpp
@@ -0,0 +1,291 @@
+//===- GraphBuilder.cpp -----------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "GraphBuilder.h"
+
+#include "llvm/BinaryFormat/ELF.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCDisassembler/MCDisassembler.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstPrinter.h"
+#include "llvm/MC/MCInstrAnalysis.h"
+#include "llvm/MC/MCInstrDesc.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Object/Binary.h"
+#include "llvm/Object/COFF.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include <functional>
+
+using Instr = llvm::cfi_verify::FileAnalysis::Instr;
+
+namespace llvm {
+namespace cfi_verify {
+
+uint64_t SearchLengthForUndef;
+uint64_t SearchLengthForConditionalBranch;
+
+static cl::opt<uint64_t, true> SearchLengthForUndefArg(
+ "search-length-undef",
+ cl::desc("Specify the maximum amount of instructions "
+ "to inspect when searching for an undefined "
+ "instruction from a conditional branch."),
+ cl::location(SearchLengthForUndef), cl::init(2));
+
+static cl::opt<uint64_t, true> SearchLengthForConditionalBranchArg(
+ "search-length-cb",
+ cl::desc("Specify the maximum amount of instructions "
+ "to inspect when searching for a conditional "
+ "branch from an indirect control flow."),
+ cl::location(SearchLengthForConditionalBranch), cl::init(20));
+
+std::vector<uint64_t> GraphResult::flattenAddress(uint64_t Address) const {
+ std::vector<uint64_t> Addresses;
+
+ auto It = IntermediateNodes.find(Address);
+ Addresses.push_back(Address);
+
+ while (It != IntermediateNodes.end()) {
+ Addresses.push_back(It->second);
+ It = IntermediateNodes.find(It->second);
+ }
+ return Addresses;
+}
+
+GraphResult GraphBuilder::buildFlowGraph(const FileAnalysis &Analysis,
+ uint64_t Address) {
+ GraphResult Result;
+ Result.BaseAddress = Address;
+ DenseSet<uint64_t> OpenedNodes;
+
+ const auto &IndirectInstructions = Analysis.getIndirectInstructions();
+
+ if (IndirectInstructions.find(Address) == IndirectInstructions.end())
+ return Result;
+
+ buildFlowGraphImpl(Analysis, OpenedNodes, Result, Address, 0);
+ return Result;
+}
+
+void GraphBuilder::buildFlowsToUndefined(const FileAnalysis &Analysis,
+ GraphResult &Result,
+ ConditionalBranchNode &BranchNode,
+ const Instr &BranchInstrMeta) {
+ assert(SearchLengthForUndef > 0 &&
+ "Search length for undefined flow must be greater than zero.");
+
+ // Start setting up the next node in the block.
+ uint64_t NextAddress = 0;
+ const Instr *NextMetaPtr;
+
+ // Find out the next instruction in the block and add it to the new
+ // node.
+ if (BranchNode.Target && !BranchNode.Fallthrough) {
+ // We know the target of the branch, find the fallthrough.
+ NextMetaPtr = Analysis.getNextInstructionSequential(BranchInstrMeta);
+ if (!NextMetaPtr) {
+ errs() << "Failed to get next instruction from "
+ << format_hex(BranchNode.Address, 2) << ".\n";
+ return;
+ }
+
+ NextAddress = NextMetaPtr->VMAddress;
+ BranchNode.Fallthrough =
+ NextMetaPtr->VMAddress; // Add the new node to the branch head.
+ } else if (BranchNode.Fallthrough && !BranchNode.Target) {
+ // We already know the fallthrough, evaluate the target.
+ uint64_t Target;
+ if (!Analysis.getMCInstrAnalysis()->evaluateBranch(
+ BranchInstrMeta.Instruction, BranchInstrMeta.VMAddress,
+ BranchInstrMeta.InstructionSize, Target)) {
+ errs() << "Failed to get branch target for conditional branch at address "
+ << format_hex(BranchInstrMeta.VMAddress, 2) << ".\n";
+ return;
+ }
+
+ // Resolve the meta pointer for the target of this branch.
+ NextMetaPtr = Analysis.getInstruction(Target);
+ if (!NextMetaPtr) {
+ errs() << "Failed to find instruction at address "
+ << format_hex(Target, 2) << ".\n";
+ return;
+ }
+
+ NextAddress = Target;
+ BranchNode.Target =
+ NextMetaPtr->VMAddress; // Add the new node to the branch head.
+ } else {
+ errs() << "ControlBranchNode supplied to buildFlowsToUndefined should "
+ "provide Target xor Fallthrough.\n";
+ return;
+ }
+
+ uint64_t CurrentAddress = NextAddress;
+ const Instr *CurrentMetaPtr = NextMetaPtr;
+
+ // Now the branch head has been set properly, complete the rest of the block.
+ for (uint64_t i = 1; i < SearchLengthForUndef; ++i) {
+ // Check to see whether the block should die.
+ if (Analysis.isCFITrap(*CurrentMetaPtr)) {
+ BranchNode.CFIProtection = true;
+ return;
+ }
+
+ // Find the metadata of the next instruction.
+ NextMetaPtr = Analysis.getDefiniteNextInstruction(*CurrentMetaPtr);
+ if (!NextMetaPtr)
+ return;
+
+ // Setup the next node.
+ NextAddress = NextMetaPtr->VMAddress;
+
+ // Add this as an intermediate.
+ Result.IntermediateNodes[CurrentAddress] = NextAddress;
+
+ // Move the 'current' pointers to the new tail of the block.
+ CurrentMetaPtr = NextMetaPtr;
+ CurrentAddress = NextAddress;
+ }
+
+ // Final check of the last thing we added to the block.
+ if (Analysis.isCFITrap(*CurrentMetaPtr))
+ BranchNode.CFIProtection = true;
+}
+
+void GraphBuilder::buildFlowGraphImpl(const FileAnalysis &Analysis,
+ DenseSet<uint64_t> &OpenedNodes,
+ GraphResult &Result, uint64_t Address,
+ uint64_t Depth) {
+ // If we've exceeded the flow length, terminate.
+ if (Depth >= SearchLengthForConditionalBranch) {
+ Result.OrphanedNodes.push_back(Address);
+ return;
+ }
+
+ // Ensure this flow is acyclic.
+ if (OpenedNodes.count(Address))
+ Result.OrphanedNodes.push_back(Address);
+
+ // If this flow is already explored, stop here.
+ if (Result.IntermediateNodes.count(Address))
+ return;
+
+ // Get the metadata for the node instruction.
+ const auto &InstrMetaPtr = Analysis.getInstruction(Address);
+ if (!InstrMetaPtr) {
+ errs() << "Failed to build flow graph for instruction at address "
+ << format_hex(Address, 2) << ".\n";
+ Result.OrphanedNodes.push_back(Address);
+ return;
+ }
+ const auto &ChildMeta = *InstrMetaPtr;
+
+ OpenedNodes.insert(Address);
+ std::set<const Instr *> CFCrossRefs =
+ Analysis.getDirectControlFlowXRefs(ChildMeta);
+
+ bool HasValidCrossRef = false;
+
+ for (const auto *ParentMetaPtr : CFCrossRefs) {
+ assert(ParentMetaPtr && "CFCrossRefs returned nullptr.");
+ const auto &ParentMeta = *ParentMetaPtr;
+ const auto &ParentDesc =
+ Analysis.getMCInstrInfo()->get(ParentMeta.Instruction.getOpcode());
+
+ if (!ParentDesc.mayAffectControlFlow(ParentMeta.Instruction,
+ *Analysis.getRegisterInfo())) {
+ // If this cross reference doesn't affect CF, continue the graph.
+ buildFlowGraphImpl(Analysis, OpenedNodes, Result, ParentMeta.VMAddress,
+ Depth + 1);
+ Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
+ HasValidCrossRef = true;
+ continue;
+ }
+
+ // Evaluate the branch target to ascertain whether this XRef is the result
+ // of a fallthrough or the target of a branch.
+ uint64_t BranchTarget;
+ if (!Analysis.getMCInstrAnalysis()->evaluateBranch(
+ ParentMeta.Instruction, ParentMeta.VMAddress,
+ ParentMeta.InstructionSize, BranchTarget)) {
+ errs() << "Failed to evaluate branch target for instruction at address "
+ << format_hex(ParentMeta.VMAddress, 2) << ".\n";
+ Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
+ Result.OrphanedNodes.push_back(ParentMeta.VMAddress);
+ continue;
+ }
+
+ // Allow unconditional branches to be part of the upwards traversal.
+ if (ParentDesc.isUnconditionalBranch()) {
+ // Ensures that the unconditional branch is actually an XRef to the child.
+ if (BranchTarget != Address) {
+ errs() << "Control flow to " << format_hex(Address, 2)
+ << ", but target resolution of "
+ << format_hex(ParentMeta.VMAddress, 2)
+ << " is not this address?\n";
+ Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
+ Result.OrphanedNodes.push_back(ParentMeta.VMAddress);
+ continue;
+ }
+
+ buildFlowGraphImpl(Analysis, OpenedNodes, Result, ParentMeta.VMAddress,
+ Depth + 1);
+ Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
+ HasValidCrossRef = true;
+ continue;
+ }
+
+ // Ensure that any unknown CFs are caught.
+ if (!ParentDesc.isConditionalBranch()) {
+ errs() << "Unknown control flow encountered when building graph at "
+ << format_hex(Address, 2) << "\n.";
+ Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
+ Result.OrphanedNodes.push_back(ParentMeta.VMAddress);
+ continue;
+ }
+
+ // Only direct conditional branches should be present at this point. Setup
+ // a conditional branch node and build flows to the ud2.
+ ConditionalBranchNode BranchNode;
+ BranchNode.Address = ParentMeta.VMAddress;
+ BranchNode.Target = 0;
+ BranchNode.Fallthrough = 0;
+ BranchNode.CFIProtection = false;
+
+ if (BranchTarget == Address)
+ BranchNode.Target = Address;
+ else
+ BranchNode.Fallthrough = Address;
+
+ HasValidCrossRef = true;
+ buildFlowsToUndefined(Analysis, Result, BranchNode, ParentMeta);
+ Result.ConditionalBranchNodes.push_back(BranchNode);
+ }
+
+ if (!HasValidCrossRef)
+ Result.OrphanedNodes.push_back(Address);
+
+ OpenedNodes.erase(Address);
+}
+
+} // namespace cfi_verify
+} // namespace llvm
diff --git a/llvm/tools/llvm-cfi-verify/lib/GraphBuilder.h b/llvm/tools/llvm-cfi-verify/lib/GraphBuilder.h
new file mode 100644
index 00000000000..3536520d590
--- /dev/null
+++ b/llvm/tools/llvm-cfi-verify/lib/GraphBuilder.h
@@ -0,0 +1,133 @@
+//===- GraphBuilder.h -------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CFI_VERIFY_GRAPH_BUILDER_H
+#define LLVM_CFI_VERIFY_GRAPH_BUILDER_H
+
+#include "FileAnalysis.h"
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/BinaryFormat/ELF.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCDisassembler/MCDisassembler.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstPrinter.h"
+#include "llvm/MC/MCInstrAnalysis.h"
+#include "llvm/MC/MCInstrDesc.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Object/Binary.h"
+#include "llvm/Object/COFF.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include <functional>
+#include <set>
+#include <string>
+#include <unordered_map>
+
+using Instr = llvm::cfi_verify::FileAnalysis::Instr;
+
+namespace llvm {
+namespace cfi_verify {
+
+extern uint64_t SearchLengthForUndef;
+extern uint64_t SearchLengthForConditionalBranch;
+
+struct ConditionalBranchNode {
+ uint64_t Address;
+ uint64_t Target;
+ uint64_t Fallthrough;
+ // Does this conditional branch look like it's used for CFI protection? i.e.
+ // - The exit point of a basic block whos entry point is {target|fallthrough}
+ // is a CFI trap, and...
+ // - The exit point of the other basic block is an undirect CF instruction.
+ bool CFIProtection;
+};
+
+// The canonical graph result structure returned by GraphBuilder. The members
+// in this structure encapsulate all possible code paths to the instruction
+// located at `BaseAddress`.
+struct GraphResult {
+ uint64_t BaseAddress;
+
+ // Map between an instruction address, and the address of the next instruction
+ // that will be executed. This map will contain all keys in the range:
+ // - [orphaned node, base address)
+ // - [conditional branch node {target|fallthrough}, base address)
+ DenseMap<uint64_t, uint64_t> IntermediateNodes;
+
+ // A list of orphaned nodes. A node is an 'orphan' if it meets any of the
+ // following criteria:
+ // - The length of the path from the base to this node has exceeded
+ // `SearchLengthForConditionalBranch`.
+ // - The node has no cross references to it.
+ // - The path from the base to this node is cyclic.
+ std::vector<uint64_t> OrphanedNodes;
+
+ // A list of top-level conditional branches that exist at the top of any
+ // non-orphan paths from the base.
+ std::vector<ConditionalBranchNode> ConditionalBranchNodes;
+
+ // Returns an in-order list of the path between the address provided and the
+ // base. The provided address must be part of this graph, and must not be a
+ // conditional branch.
+ std::vector<uint64_t> flattenAddress(uint64_t Address) const;
+};
+
+class GraphBuilder {
+public:
+ // Build the control flow graph for a provided control flow node. This method
+ // will enumerate all branch nodes that can lead to this node, and place them
+ // into GraphResult::ConditionalBranchNodes. It will also provide any orphaned
+ // (i.e. the upwards traversal did not make it to a branch node) flows to the
+ // provided node in GraphResult::OrphanedNodes.
+ static GraphResult buildFlowGraph(const FileAnalysis &Analysis,
+ uint64_t Address);
+
+private:
+ // Implementation function that actually builds the flow graph. Retrieves a
+ // list of cross references to instruction referenced in `Address`. If any of
+ // these XRefs are conditional branches, it will build the other potential
+ // path (fallthrough or target) using `buildFlowsToUndefined`. Otherwise, this
+ // function will recursively call itself where `Address` in the recursive call
+ // is now the XRef. If any XRef is an orphan, it is added to
+ // `Result.OrphanedNodes`. `OpenedNodes` keeps track of the list of nodes
+ // in the current path and is used for cycle-checking. If the path is found
+ // to be cyclic, it will be added to `Result.OrphanedNodes`.
+ static void buildFlowGraphImpl(const FileAnalysis &Analysis,
+ DenseSet<uint64_t> &OpenedNodes,
+ GraphResult &Result, uint64_t Address,
+ uint64_t Depth);
+
+ // Utilised by buildFlowGraphImpl to build the tree out from the provided
+ // conditional branch node to an undefined instruction. The provided
+ // conditional branch node must have exactly one of its subtrees set, and will
+ // update the node's CFIProtection field if a deterministic flow can be found
+ // to an undefined instruction.
+ static void buildFlowsToUndefined(const FileAnalysis &Analysis,
+ GraphResult &Result,
+ ConditionalBranchNode &BranchNode,
+ const Instr &BranchInstrMeta);
+};
+
+} // end namespace cfi_verify
+} // end namespace llvm
+
+#endif // LLVM_CFI_VERIFY_GRAPH_BUILDER_H
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