SecBSD's official ports repository

devel/llvm/patches/patch-include_llvm_InitializePasses_h

@@ -0,0 +1,29 @@
+Add RETGUARD to clang for amd64. This security mechanism uses per-function
+random cookies to protect access to function return instructions, with the
+effect that the integrity of the return address is protected, and function
+return instructions are harder to use in ROP gadgets.
+
+On function entry the return address is combined with a per-function random
+cookie and stored in the stack frame. The integrity of this value is verified
+before function return, and if this check fails, the program aborts. In this way
+RETGUARD is an improved stack protector, since the cookies are per-function. The
+verification routine is constructed such that the binary space immediately
+before each ret instruction is padded with int03 instructions, which makes these
+return instructions difficult to use in ROP gadgets. In the kernel, this has the
+effect of removing approximately 50% of total ROP gadgets, and 15% of unique
+ROP gadgets compared to the 6.3 release kernel. Function epilogues are
+essentially gadget free, leaving only the polymorphic gadgets that result from
+jumping into the instruction stream partway through other instructions. Work to
+remove these gadgets will continue through other mechanisms.
+
+Index: include/llvm/InitializePasses.h
+--- include/llvm/InitializePasses.h.orig
++++ include/llvm/InitializePasses.h
+@@ -387,6 +387,7 @@ void initializeRemoveRedundantDebugValuesPass(PassRegi
+ void initializeRenameIndependentSubregsPass(PassRegistry&);
+ void initializeReplaceWithVeclibLegacyPass(PassRegistry &);
+ void initializeResetMachineFunctionPass(PassRegistry&);
++void initializeReturnProtectorPass(PassRegistry&);
+ void initializeReversePostOrderFunctionAttrsLegacyPassPass(PassRegistry&);
+ void initializeRewriteStatepointsForGCLegacyPassPass(PassRegistry &);
+ void initializeRewriteSymbolsLegacyPassPass(PassRegistry&);