From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f202.google.com (mail-qk1-f202.google.com [209.85.222.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 98ACA72 for ; Thu, 30 Sep 2021 18:05:35 +0000 (UTC) Received: by mail-qk1-f202.google.com with SMTP id v14-20020a05620a0f0e00b0043355ed67d1so14255442qkl.7 for ; Thu, 30 Sep 2021 11:05:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=d2ahcIWGgjFLa51IYF/IRgZQTxiFTIrN8xyd61bx7ZU=; b=NhbAP7unTGwhWdPvJeWACQ1TDF5GXMPv+0MBfQlPCnaKXOZdSPEz5uCF6RDloP1n8b OwibjpId8oQguIS9uQbd1xpiZvTdbsEjyOqUTKphGudM8vdeEoJE7cAGBlFxOst9k01U nWM5yQQbK70Eh4imuXPyktRhBnlYsPK5HPGNbDPrfioMoHlvyR8UXoIOBejRVOJgtyPL Kv99RotkBHZSIpXgJ1aow4PYNRvWmX9MLsO/YQJn/O5XJTviFbQNetqfMC0aoOiJnlpK ncO9vdcOujtWUksHqhILZw9nVEPRbCRxukd/ItEualssEXi6n6N7/R6Jqb9ZI0IKnpXy hc/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=d2ahcIWGgjFLa51IYF/IRgZQTxiFTIrN8xyd61bx7ZU=; b=ZcRlCwD2rQGFsAhWTAAVzZf4mtnlz0QZgNly4NshY6Phmh5g20iHJSnV8thelMBkDg 6O0aCWhdCqRQCBnPl/8I+l/Wd4wDFfj31+T8LiXWhZHChZdqvaCMK+R4DF+XHpbholVe 3JgM1FC5MaUX2ZfHNET/aoywQeeiylf4GtTQ6eCe8zKaLD9seVGnXUAP8r8lfuOpmi6n VPWrq/v6VaGlLttCvYv0/nqABW7aJgQGwx+4EwALwzJEe60CTiYa6p9B1xVPfa4GWNIt cmN+OU4003FAn3p8b1UaYJl6FZjbZ2Rshqzv8eZz1W0bKmr/jp5wEzkRVXGtoY3X2IKq Q0ww== X-Gm-Message-State: AOAM533VPuOrrN+UKiQnHWDCr/wnV7nR8SQjvsaM6y+GqSi19VRbNOV1 pSoal5GOYRIJdhKJLSuEEUyBl8jejCYQJQi/Ung= X-Google-Smtp-Source: ABdhPJy34QBbONh0nYYsCE3geeKJiBHRElBYm2K2StDlG2pt1e7d/J1trbAIyBj0A4qx9m58AymxwIjArJ9EDAX8EPY= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:ce43:4366:95ca:d6e9]) (user=samitolvanen job=sendgmr) by 2002:a05:6214:1022:: with SMTP id k2mr5342357qvr.53.1633025134523; Thu, 30 Sep 2021 11:05:34 -0700 (PDT) Date: Thu, 30 Sep 2021 11:05:16 -0700 Message-Id: <20210930180531.1190642-1-samitolvanen@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.33.0.800.g4c38ced690-goog Subject: [PATCH v4 00/15] x86: Add support for Clang CFI From: Sami Tolvanen To: x86@kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , Nathan Chancellor , Nick Desaulniers , Sedat Dilek , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" This series adds support for Clang's Control-Flow Integrity (CFI) checking to x86_64. With CFI, the compiler injects a runtime check before each indirect function call to ensure the target is a valid function with the correct static type. This restricts possible call targets and makes it more difficult for an attacker to exploit bugs that allow the modification of stored function pointers. For more details, see: https://clang.llvm.org/docs/ControlFlowIntegrity.html Note that v4 is based on tip/master. The first two patches contain objtool support for CFI, the remaining patches change function declarations to use opaque types, fix type mismatch issues that confuse the compiler, and disable CFI where it can't be used. You can also pull this series from https://github.com/samitolvanen/linux.git x86-cfi-v4 --- Changes in v4: - Dropped the extable patch after the code was refactored in -tip. - Switched to __section() instead of open-coding the attribute. - Added an explicit ifdef for filtering out CC_FLAGS_CFI in purgatory for readability. - Added a comment to arch_cfi_jump_reloc_offset() in objtool. Changes in v3: - Dropped Clang requirement to >= 13 after the missing compiler fix was backported there. - Added DEFINE_CFI_IMMEDIATE_RETURN_STUB to address the issue with tp_stub_func in kernel/tracepoint.c. - Renamed asm_func_t to asm_func_ptr. - Changed extable handlers to use __cficanonical instead of disabling CFI for fixup_exception. Changes in v2: - Dropped the first objtool patch as the warnings were fixed in separate patches. - Changed fix_cfi_relocs() in objtool to not rely on jump table symbols, and to return an error if it can't find a relocation. - Fixed a build issue with ASM_STACK_FRAME_NON_STANDARD(). - Dropped workarounds for inline assembly references to address-taken static functions with CFI as this was fixed in the compiler. - Changed the C declarations of non-callable functions to use opaque types and dropped the function_nocfi() patches. - Changed ARCH_SUPPORTS_CFI_CLANG to depend on Clang >=14 for the compiler fixes. Kees Cook (1): x86, relocs: Ignore __typeid__ relocations Sami Tolvanen (14): objtool: Add CONFIG_CFI_CLANG support objtool: Add ASM_STACK_FRAME_NON_STANDARD linkage: Add DECLARE_ASM_FUNC_SYMBOL cfi: Add DEFINE_CFI_IMMEDIATE_RETURN_STUB tracepoint: Exclude tp_stub_func from CFI checking ftrace: Use an opaque type for functions not callable from C lkdtm: Disable UNSET_SMEP with CFI lkdtm: Use an opaque type for lkdtm_rodata_do_nothing x86: Use an opaque type for functions not callable from C x86/purgatory: Disable CFI x86, module: Ignore __typeid__ relocations x86, cpu: Use LTO for cpu.c with CFI x86, kprobes: Fix optprobe_template_func type mismatch x86, build: Allow CONFIG_CFI_CLANG to be selected arch/x86/Kconfig | 1 + arch/x86/include/asm/ftrace.h | 2 +- arch/x86/include/asm/idtentry.h | 10 +++--- arch/x86/include/asm/page_64.h | 7 ++-- arch/x86/include/asm/paravirt_types.h | 3 +- arch/x86/include/asm/processor.h | 2 +- arch/x86/include/asm/proto.h | 25 ++++++------- arch/x86/include/asm/uaccess_64.h | 9 ++--- arch/x86/kernel/alternative.c | 2 +- arch/x86/kernel/ftrace.c | 2 +- arch/x86/kernel/kprobes/opt.c | 4 +-- arch/x86/kernel/module.c | 4 +++ arch/x86/kernel/paravirt.c | 4 +-- arch/x86/kvm/emulate.c | 4 +-- arch/x86/kvm/kvm_emulate.h | 9 ++--- arch/x86/power/Makefile | 2 ++ arch/x86/purgatory/Makefile | 4 +++ arch/x86/tools/relocs.c | 7 ++++ arch/x86/xen/enlighten_pv.c | 6 ++-- arch/x86/xen/xen-ops.h | 10 +++--- drivers/misc/lkdtm/bugs.c | 2 +- drivers/misc/lkdtm/lkdtm.h | 2 +- drivers/misc/lkdtm/perms.c | 2 +- drivers/misc/lkdtm/rodata.c | 2 +- include/asm-generic/vmlinux.lds.h | 11 ++++++ include/linux/cfi.h | 13 +++++++ include/linux/ftrace.h | 7 ++-- include/linux/linkage.h | 13 +++++++ include/linux/objtool.h | 6 ++++ kernel/cfi.c | 24 ++++++++++++- kernel/tracepoint.c | 5 +-- tools/include/linux/objtool.h | 6 ++++ tools/objtool/arch/x86/decode.c | 17 +++++++++ tools/objtool/elf.c | 51 +++++++++++++++++++++++++++ tools/objtool/include/objtool/arch.h | 3 ++ tools/objtool/include/objtool/elf.h | 2 +- 36 files changed, 217 insertions(+), 66 deletions(-) base-commit: d4bfebd9ef497ee0afb498f6028a5074a6ccf307 -- 2.33.0.800.g4c38ced690-goog