Date: Thu, 21 Nov 2019 18:21:04 -0800 From: Eric Biggers <ebiggers@...nel.org> To: Kees Cook <keescook@...omium.org> Cc: Herbert Xu <herbert@...dor.apana.org.au>, João Moreira <joao.moreira@...el.com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Sami Tolvanen <samitolvanen@...gle.com>, Stephan Mueller <smueller@...onox.de>, x86@...nel.org, linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com Subject: Re: [PATCH v6 0/8] crypto: x86: Fix indirect function call casts On Thu, Nov 21, 2019 at 05:03:26PM -0800, Kees Cook wrote: > v6: > - minimize need for various internal casts (ebiggers) > - clarify comments (ebiggers) > - switch all context pointers to const (ebiggers) > v5: https://firstname.lastname@example.org > v4: https://email@example.com > v3: https://firstname.lastname@example.org > > Hi, > > Now that Clang's CFI has been fixed to do the right thing with extern > asm functions, this patch series is much simplified. Repeating patch > 1's commit log here: > > The crypto glue performed function prototype casting to make indirect > calls to assembly routines. Instead of performing casts at the call > sites (which trips Control Flow Integrity prototype checking), switch > each prototype to a common standard set of arguments which allows the > incremental removal of the existing macros. In order to keep pointer > math unchanged, internal casting between u128 pointers and u8 pointers > is added. > > With this series (and the Clang LTO+CFI series) I am able to boot x86 > with all crytpo selftests enabled without tripping any CFI checks. > > Thanks! > > -Kees > > Kees Cook (8): > crypto: x86/glue_helper: Regularize function prototypes > crypto: x86/serpent: Remove glue function macros usage > crypto: x86/camellia: Remove glue function macro usage > crypto: x86/twofish: Remove glue function macro usage > crypto: x86/cast6: Remove glue function macro usage > crypto: x86/aesni: Remove glue function macro usage > crypto: x86/glue_helper: Remove function prototype cast helpers > crypto, x86/sha: Eliminate casts on asm implementations This patchset doesn't actually compile until patch 6/8, due to -Werror=incompatible-pointer-types in the kernel's top-level Makefile. It's generally expected that every kernel commit compiles, and I'm not sure it's a good idea to allow any exceptions. The easiest solution would be to just squash the first 6 patches together into one big patch. Alternatively, 'ccflags-y := -Wno-error=incompatible-pointer-types' could be added to arch/x86/crypto/Makefile in patch 1 and removed in patch 7. - Eric
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