From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F17DDECAAD4 for ; Tue, 30 Aug 2022 23:31:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231564AbiH3Xbk (ORCPT ); Tue, 30 Aug 2022 19:31:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231358AbiH3Xbh (ORCPT ); Tue, 30 Aug 2022 19:31:37 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C6C072B77 for ; Tue, 30 Aug 2022 16:31:36 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id y9-20020a17090322c900b00174c881abaeso4520814plg.6 for ; Tue, 30 Aug 2022 16:31:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc:subject:date; bh=L25uLgv5hznFOW8C65x6whtc7Tn9BJysM2Vvz8HWyDE=; b=GlyX/udszzm3ETI6dGBsinPgbb2zH2Sx7UXYz/1vjC/nGY+/X7ZLW46uqN3etLOPT0 gV1SaWu+mT9dOl7PKHrdCe9i+XWpddw8gn1LLlyKiAiZDyL18nKBWphU62pG+hJKxRmM u+uoRGf2SWIvXTlojSYkQR+2T7yMZdfaE77HWRA76cmFOBZRkZN023sEPCVRGdvc5u7V WBxTSYiDyS+PUfPxQvu0l+seugBhnhEOip5lzg5qUgw3A6gDkzqA0gqRlSgn+YUgNTBq ekG0EJpcTzqD+Y4jhU0JnnShqvo1JQRejynQVVRjwAZ9ll4kYjRhz7z/Zm+n5si+aKge f35w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date; bh=L25uLgv5hznFOW8C65x6whtc7Tn9BJysM2Vvz8HWyDE=; b=wF93yGRyROCFaKiKNg36r2DRVypJfG32ybmaM8cMUH1tN6i//okVIVZXdDz4bq1QN0 TQLm/Xqn2DaekIPKFwcjURQKJ+CTYJTwvpDlphTy32ofjvQVyFGsERQKfcL53U7WH81m 7++RJMBTlTjz+JpCzYBAKWRITD+1C4PxgWOr+5wSd+oXBdoeiz3CBHH3j/y0k6/ZzdI/ saZgJcYGVpHBDyZOhAXQ8X1ODrVfz2MCgR2MbOhLZKaVgWFeHgfAmRJU3MZJ4i8l2bxO 7GQkdYne4tR34MgSeq4lB7TGj2WUT3pyxaLmhFKL4xuYrG54k/EDA5NynmE3pjRqwvnt y5EA== X-Gm-Message-State: ACgBeo3ue7gyb/vm6LBHe9LLChqoja2D/c4IUiL1SbcwVNXDJa8wCG0H nqIjyFBQtsGn5hFrKGEBjFlsYH8Xx7obfaO0SqoYWxCHKQQqMcyycV/JxpCUdIMuhDG5iVE7tJn CiungsNdJtJorrctDl/Z8Q2gFz6dVKEVlKfJbSU1EuI6a0XMVMTbvJJscNRw+CNEE8xBAB7lOCI IREoZTNYY0kw== X-Google-Smtp-Source: AA6agR6t6+RmUgXGfCDMkXtgpmsLFiEpc19Ih8//1Ts8Vdoix/62fuolHALxDz5NswEPkfsF2/qhJD8nw7h8pAHo2gs= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:54d9:7143:6a7d:91d]) (user=samitolvanen job=sendgmr) by 2002:a17:90a:249:b0:1e0:a8a3:3c6c with SMTP id t9-20020a17090a024900b001e0a8a33c6cmr14044pje.0.1661902295271; Tue, 30 Aug 2022 16:31:35 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:09 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-2-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=2946; i=samitolvanen@google.com; h=from:subject; bh=Y2KllNLLe5W3ojqZsH1L8RGIJ3+vQcqt1B34SGCIoIw=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3LFZnyR8Aq9IX9f3NCTQfZ9PLKXxM9T7+t9pe6 XCRRtGeJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dywAKCRBMtfaEi7xW7vF8C/ 0Q2tFR9IU/s09oK/aPYzy2OnR4Fl7grWpQwG8dbDwI9bQFdE58qu5aKvOkH1n5LoPMnx1oiPeKAua8 Xbr93KRYEltkTaD58AlXyUTQVb8W/+WK4z5r0qhm6P2JWbCqvDwg4StkJRSB7vDn+lmR/PA0lfUQob tOp1QJGiNuDLFc0TbTSfqkK/xMXR6a0+FdfMXg20QKWShLiYE7bYKvgl6pguSour1sba5xcznBLxV3 M+9Ri4Nnvzd0QnR7bku4sNbS59EpdZ9c5D6eJjbsmZwIrBklT2i9BvcfHx4n6HCM+M0pWiFtQTUUXK ZDwfY8tjUVanTK7afJi3m5XLWkUlmJhaxk1YjwGK1wpbf+kcj9ykRivZnnU/eqNPtW/jP1Tk3ixLUv ceQHLD74GD+/xpPl9+6/1b0LWdDFc2ephQ2+kiVVS5zMGX+bRduupKomCFdvdHgAf1GrFAJb7iKA9R JE6m9yMp4f9no/FyLoJGQiPKz1klAidmbOixNOnCretWc= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 01/21] treewide: Filter out CC_FLAGS_CFI From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In preparation for removing CC_FLAGS_CFI from CC_FLAGS_LTO, explicitly filter out CC_FLAGS_CFI in all the makefiles where we currently filter out CC_FLAGS_LTO. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/arm64/kernel/vdso/Makefile | 3 ++- arch/x86/entry/vdso/Makefile | 3 ++- drivers/firmware/efi/libstub/Makefile | 2 ++ 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makef= ile index bafbf78fab77..619e2dc7ee14 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -40,7 +40,8 @@ ccflags-y +=3D -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO # kernel with CONFIG_WERROR enabled. CFLAGS_REMOVE_vgettimeofday.o =3D $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \ $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \ - $(CC_FLAGS_LTO) -Wmissing-prototypes -Wmissing-declarations + $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \ + -Wmissing-prototypes -Wmissing-declarations KASAN_SANITIZE :=3D n KCSAN_SANITIZE :=3D n UBSAN_SANITIZE :=3D n diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 12f6c4d714cd..381d3333b996 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -91,7 +91,7 @@ ifneq ($(RETPOLINE_VDSO_CFLAGS),) endif endif =20 -$(vobjs): KBUILD_CFLAGS :=3D $(filter-out $(CC_FLAGS_LTO) $(RANDSTRUCT_CFL= AGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) +$(vobjs): KBUILD_CFLAGS :=3D $(filter-out $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) = $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFL= AGS)) $(CFL) $(vobjs): KBUILD_AFLAGS +=3D -DBUILD_VDSO =20 # @@ -153,6 +153,7 @@ KBUILD_CFLAGS_32 :=3D $(filter-out $(RANDSTRUCT_CFLAGS)= ,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 :=3D $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_3= 2)) KBUILD_CFLAGS_32 :=3D $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 :=3D $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 :=3D $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 +=3D -m32 -msoft-float -mregparm=3D0 -fpic KBUILD_CFLAGS_32 +=3D -fno-stack-protector KBUILD_CFLAGS_32 +=3D $(call cc-option, -foptimize-sibling-calls) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/l= ibstub/Makefile index d0537573501e..234fb2910622 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -39,6 +39,8 @@ KBUILD_CFLAGS :=3D $(cflags-y) -Os -DDISABLE_BRANCH_PRO= FILING \ =20 # remove SCS flags from all objects in this directory KBUILD_CFLAGS :=3D $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS)) +# disable CFI +KBUILD_CFLAGS :=3D $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS)) # disable LTO KBUILD_CFLAGS :=3D $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS)) =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 434E7ECAAD4 for ; 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Tue, 30 Aug 2022 16:31:38 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:10 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-3-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=815; i=samitolvanen@google.com; h=from:subject; bh=ZsdbFV1rDPVMEEnz8gpkcJ4SEVi2nPPUZtGW8C9VlOE=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3LuiRNOIXF6iWJdViGqd3zv5mS4LojAiJ+2zw1 RBe4TiiJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dywAKCRBMtfaEi7xW7hbdC/ 9dH+eF9FLRfbAZmIKkZfKGLDEV4GpzyFt3DC0T+XPYawpv8d4hIHcmWOewSokNp8/RlQxEqhucG9Zn axIaqhwCi2QhLKvRZcwmhKgvB25LWwrp6pMh94YrnGXvlD4ZGovDQk7afANRYpvaJuBWvNDjJMfcM9 IMHPn/dIoby0cmKnGFT9OKty5s0M6RvrxxqzZZEVxwms885iZiHHnH1gSB2c5RlKNgSxrpvfzr6gB5 VgzIUn3LcrpQ9eYEcaYRquZJotPXSZwdymKNF+l7zsSqZZzMkyXcLEY8JSPcDyhYBdFlHyA9oq+hqf FOCm74Um/Gr8A1LV7ognHe7JEPGjOh7sx3AJcXUtyPCn7FtdZU2V/f+thDRCL7FfgnF9UDZs0DMpqq PT0C1GB58hHVS0/Y/twOGM7f//NBSc140Y0yOTXRWtQuwHvAzfA6mSE55KlboU2m6pMC8JKeSW7PsL +uWT5s6GcBEfGDclqFu6GC1EpRCfJ/6w0iOUYXTCADGSE= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 02/21] scripts/kallsyms: Ignore __kcfi_typeid_ From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The compiler generates __kcfi_typeid_ symbols for annotating assembly functions with type information. These are constants that can be referenced in assembly code and are resolved by the linker. Ignore them in kallsyms. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- scripts/kallsyms.c | 1 + 1 file changed, 1 insertion(+) diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index f18e6dfc68c5..ccdf0c897f31 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -119,6 +119,7 @@ static bool is_ignored_symbol(const char *name, char ty= pe) "__ThumbV7PILongThunk_", "__LA25Thunk_", /* mips lld */ "__microLA25Thunk_", + "__kcfi_typeid_", /* CFI type identifiers */ NULL }; =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2905ECAAD5 for ; Tue, 30 Aug 2022 23:32:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231497AbiH3XcE (ORCPT ); Tue, 30 Aug 2022 19:32:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231741AbiH3Xbv (ORCPT ); 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Tue, 30 Aug 2022 16:31:41 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:11 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=10385; i=samitolvanen@google.com; h=from:subject; bh=siBrxi9qEY+bHfrdDLbSgqN76qbbdTlvUNSEbiqEl7E=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3MATW3VwEhVluICkF7vpOjQP1+tSli4MFo4T+X PTJsmySJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzAAKCRBMtfaEi7xW7pd7C/ 4ipjawGn1OkRVL5Ob5r10peEgVkvGylpgkc9pjaGMupRLdCHHy7/drjCLdklBNODdjAsd7PHatm6Fn AchDqGFTFCUm/XQdhltzt07yGXna3wqBpJS8pyljD5Z+6Jbyg2vEMRUjvVtKus8/DtCAjNAXyGtlPj Kx2hTRkK3+M2snu6VndLme0sAzl4UY8ds65a4ct+PRyrLemdbRCZUrJw/o8clsF3YSbseXAoRdOgph upgwpLT0oVD9WDxAqLunw+1d7mvwcbVx3iNndwwBZJ2sAPJ2hubTuZofsTtMgzQDUMX4e6ptSzJoDD sn7GB3CGY8CoOYjqLy3VvjJeZdXmfoahyKw6+afKgn/dYU+RlW19hgXM+jxcKJLYa9FFZ62BmhfJp5 pptKaV8gnDtzbebRAgD+6sberrvdYdMO9k8H1CIRhFv2fJP18G8TEE8MYNH4vxvxGnS9+ItZLnxO8t i/qFwlWouRxTF+hvspZswPM+C6BdI1hbKKkKuW1i0NCnU= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 03/21] cfi: Remove CONFIG_CFI_CLANG_SHADOW From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In preparation to switching to -fsanitize=3Dkcfi, remove support for the CFI module shadow that will no longer be needed. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/Kconfig | 10 -- include/linux/cfi.h | 12 --- kernel/cfi.c | 236 +------------------------------------------ kernel/module/main.c | 15 --- 4 files changed, 1 insertion(+), 272 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 5dbf11a5ba4e..5fd875e18c99 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -754,16 +754,6 @@ config CFI_CLANG =20 https://clang.llvm.org/docs/ControlFlowIntegrity.html =20 -config CFI_CLANG_SHADOW - bool "Use CFI shadow to speed up cross-module checks" - default y - depends on CFI_CLANG && MODULES - help - If you select this option, the kernel builds a fast look-up table of - CFI check functions in loaded modules to reduce performance overhead. - - If unsure, say Y. - config CFI_PERMISSIVE bool "Use CFI in permissive mode" depends on CFI_CLANG diff --git a/include/linux/cfi.h b/include/linux/cfi.h index c6dfc1ed0626..4ab51c067007 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -20,18 +20,6 @@ extern void __cfi_check(uint64_t id, void *ptr, void *di= ag); #define __CFI_ADDRESSABLE(fn, __attr) \ const void *__cfi_jt_ ## fn __visible __attr =3D (void *)&fn =20 -#ifdef CONFIG_CFI_CLANG_SHADOW - -extern void cfi_module_add(struct module *mod, unsigned long base_addr); -extern void cfi_module_remove(struct module *mod, unsigned long base_addr); - -#else - -static inline void cfi_module_add(struct module *mod, unsigned long base_a= ddr) {} -static inline void cfi_module_remove(struct module *mod, unsigned long bas= e_addr) {} - -#endif /* CONFIG_CFI_CLANG_SHADOW */ - #else /* !CONFIG_CFI_CLANG */ =20 #ifdef CONFIG_X86_KERNEL_IBT diff --git a/kernel/cfi.c b/kernel/cfi.c index 2046276ee234..e8bc1b370edc 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -32,237 +32,6 @@ static inline void handle_cfi_failure(void *ptr) } =20 #ifdef CONFIG_MODULES -#ifdef CONFIG_CFI_CLANG_SHADOW -/* - * Index type. A 16-bit index can address at most (2^16)-2 pages (taking - * into account SHADOW_INVALID), i.e. ~256M with 4k pages. - */ -typedef u16 shadow_t; -#define SHADOW_INVALID ((shadow_t)~0UL) - -struct cfi_shadow { - /* Page index for the beginning of the shadow */ - unsigned long base; - /* An array of __cfi_check locations (as indices to the shadow) */ - shadow_t shadow[1]; -} __packed; - -/* - * The shadow covers ~128M from the beginning of the module region. If - * the region is larger, we fall back to __module_address for the rest. - */ -#define __SHADOW_RANGE (_UL(SZ_128M) >> PAGE_SHIFT) - -/* The in-memory size of struct cfi_shadow, always at least one page */ -#define __SHADOW_PAGES ((__SHADOW_RANGE * sizeof(shadow_t)) >> PAGE_SHIFT) -#define SHADOW_PAGES max(1UL, __SHADOW_PAGES) -#define SHADOW_SIZE (SHADOW_PAGES << PAGE_SHIFT) - -/* The actual size of the shadow array, minus metadata */ -#define SHADOW_ARR_SIZE (SHADOW_SIZE - offsetof(struct cfi_shadow, shadow= )) -#define SHADOW_ARR_SLOTS (SHADOW_ARR_SIZE / sizeof(shadow_t)) - -static DEFINE_MUTEX(shadow_update_lock); -static struct cfi_shadow __rcu *cfi_shadow __read_mostly; - -/* Returns the index in the shadow for the given address */ -static inline int ptr_to_shadow(const struct cfi_shadow *s, unsigned long = ptr) -{ - unsigned long index; - unsigned long page =3D ptr >> PAGE_SHIFT; - - if (unlikely(page < s->base)) - return -1; /* Outside of module area */ - - index =3D page - s->base; - - if (index >=3D SHADOW_ARR_SLOTS) - return -1; /* Cannot be addressed with shadow */ - - return (int)index; -} - -/* Returns the page address for an index in the shadow */ -static inline unsigned long shadow_to_ptr(const struct cfi_shadow *s, - int index) -{ - if (unlikely(index < 0 || index >=3D SHADOW_ARR_SLOTS)) - return 0; - - return (s->base + index) << PAGE_SHIFT; -} - -/* Returns the __cfi_check function address for the given shadow location = */ -static inline unsigned long shadow_to_check_fn(const struct cfi_shadow *s, - int index) -{ - if (unlikely(index < 0 || index >=3D SHADOW_ARR_SLOTS)) - return 0; - - if (unlikely(s->shadow[index] =3D=3D SHADOW_INVALID)) - return 0; - - /* __cfi_check is always page aligned */ - return (s->base + s->shadow[index]) << PAGE_SHIFT; -} - -static void prepare_next_shadow(const struct cfi_shadow __rcu *prev, - struct cfi_shadow *next) -{ - int i, index, check; - - /* Mark everything invalid */ - memset(next->shadow, 0xFF, SHADOW_ARR_SIZE); - - if (!prev) - return; /* No previous shadow */ - - /* If the base address didn't change, an update is not needed */ - if (prev->base =3D=3D next->base) { - memcpy(next->shadow, prev->shadow, SHADOW_ARR_SIZE); - return; - } - - /* Convert the previous shadow to the new address range */ - for (i =3D 0; i < SHADOW_ARR_SLOTS; ++i) { - if (prev->shadow[i] =3D=3D SHADOW_INVALID) - continue; - - index =3D ptr_to_shadow(next, shadow_to_ptr(prev, i)); - if (index < 0) - continue; - - check =3D ptr_to_shadow(next, - shadow_to_check_fn(prev, prev->shadow[i])); - if (check < 0) - continue; - - next->shadow[index] =3D (shadow_t)check; - } -} - -static void add_module_to_shadow(struct cfi_shadow *s, struct module *mod, - unsigned long min_addr, unsigned long max_addr) -{ - int check_index; - unsigned long check =3D (unsigned long)mod->cfi_check; - unsigned long ptr; - - if (unlikely(!PAGE_ALIGNED(check))) { - pr_warn("cfi: not using shadow for module %s\n", mod->name); - return; - } - - check_index =3D ptr_to_shadow(s, check); - if (check_index < 0) - return; /* Module not addressable with shadow */ - - /* For each page, store the check function index in the shadow */ - for (ptr =3D min_addr; ptr <=3D max_addr; ptr +=3D PAGE_SIZE) { - int index =3D ptr_to_shadow(s, ptr); - - if (index >=3D 0) { - /* Each page must only contain one module */ - WARN_ON_ONCE(s->shadow[index] !=3D SHADOW_INVALID); - s->shadow[index] =3D (shadow_t)check_index; - } - } -} - -static void remove_module_from_shadow(struct cfi_shadow *s, struct module = *mod, - unsigned long min_addr, unsigned long max_addr) -{ - unsigned long ptr; - - for (ptr =3D min_addr; ptr <=3D max_addr; ptr +=3D PAGE_SIZE) { - int index =3D ptr_to_shadow(s, ptr); - - if (index >=3D 0) - s->shadow[index] =3D SHADOW_INVALID; - } -} - -typedef void (*update_shadow_fn)(struct cfi_shadow *, struct module *, - unsigned long min_addr, unsigned long max_addr); - -static void update_shadow(struct module *mod, unsigned long base_addr, - update_shadow_fn fn) -{ - struct cfi_shadow *prev; - struct cfi_shadow *next; - unsigned long min_addr, max_addr; - - next =3D vmalloc(SHADOW_SIZE); - - mutex_lock(&shadow_update_lock); - prev =3D rcu_dereference_protected(cfi_shadow, - mutex_is_locked(&shadow_update_lock)); - - if (next) { - next->base =3D base_addr >> PAGE_SHIFT; - prepare_next_shadow(prev, next); - - min_addr =3D (unsigned long)mod->core_layout.base; - max_addr =3D min_addr + mod->core_layout.text_size; - fn(next, mod, min_addr & PAGE_MASK, max_addr & PAGE_MASK); - - set_memory_ro((unsigned long)next, SHADOW_PAGES); - } - - rcu_assign_pointer(cfi_shadow, next); - mutex_unlock(&shadow_update_lock); - synchronize_rcu(); - - if (prev) { - set_memory_rw((unsigned long)prev, SHADOW_PAGES); - vfree(prev); - } -} - -void cfi_module_add(struct module *mod, unsigned long base_addr) -{ - update_shadow(mod, base_addr, add_module_to_shadow); -} - -void cfi_module_remove(struct module *mod, unsigned long base_addr) -{ - update_shadow(mod, base_addr, remove_module_from_shadow); -} - -static inline cfi_check_fn ptr_to_check_fn(const struct cfi_shadow __rcu *= s, - unsigned long ptr) -{ - int index; - - if (unlikely(!s)) - return NULL; /* No shadow available */ - - index =3D ptr_to_shadow(s, ptr); - if (index < 0) - return NULL; /* Cannot be addressed with shadow */ - - return (cfi_check_fn)shadow_to_check_fn(s, index); -} - -static inline cfi_check_fn find_shadow_check_fn(unsigned long ptr) -{ - cfi_check_fn fn; - - rcu_read_lock_sched_notrace(); - fn =3D ptr_to_check_fn(rcu_dereference_sched(cfi_shadow), ptr); - rcu_read_unlock_sched_notrace(); - - return fn; -} - -#else /* !CONFIG_CFI_CLANG_SHADOW */ - -static inline cfi_check_fn find_shadow_check_fn(unsigned long ptr) -{ - return NULL; -} - -#endif /* CONFIG_CFI_CLANG_SHADOW */ =20 static inline cfi_check_fn find_module_check_fn(unsigned long ptr) { @@ -298,10 +67,7 @@ static inline cfi_check_fn find_check_fn(unsigned long = ptr) ct_irq_enter(); } =20 - if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) - fn =3D find_shadow_check_fn(ptr); - if (!fn) - fn =3D find_module_check_fn(ptr); + fn =3D find_module_check_fn(ptr); =20 if (rcu_idle) { ct_irq_exit(); diff --git a/kernel/module/main.c b/kernel/module/main.c index a4e4d84b6f4e..0228f44b58e5 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1144,8 +1144,6 @@ void __weak module_arch_freeing_init(struct module *m= od) { } =20 -static void cfi_cleanup(struct module *mod); - /* Free a module, remove from lists, etc. */ static void free_module(struct module *mod) { @@ -1190,9 +1188,6 @@ static void free_module(struct module *mod) mod->name); mutex_unlock(&module_mutex); =20 - /* Clean up CFI for the module. */ - cfi_cleanup(mod); - /* This may be empty, but that's OK */ module_arch_freeing_init(mod); module_memfree(mod->init_layout.base); @@ -2875,7 +2870,6 @@ static int load_module(struct load_info *info, const = char __user *uargs, synchronize_rcu(); kfree(mod->args); free_arch_cleanup: - cfi_cleanup(mod); module_arch_cleanup(mod); free_modinfo: free_modinfo(mod); @@ -2984,15 +2978,6 @@ static void cfi_init(struct module *mod) mod->exit =3D *exit; #endif rcu_read_unlock_sched(); 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charset="utf-8" The __CFI_ADDRESSABLE macro is used for init_module and cleanup_module to ensure we have the address of the CFI jump table, and with CONFIG_X86_KERNEL_IBT to ensure LTO won't optimize away the symbols. As __CFI_ADDRESSABLE is no longer necessary with -fsanitize=3Dkcfi, add a more flexible version of the __ADDRESSABLE macro and always ensure these symbols won't be dropped. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- include/linux/cfi.h | 20 -------------------- include/linux/compiler.h | 6 ++++-- include/linux/module.h | 4 ++-- 3 files changed, 6 insertions(+), 24 deletions(-) diff --git a/include/linux/cfi.h b/include/linux/cfi.h index 4ab51c067007..2cdbc0fbd0ab 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -13,26 +13,6 @@ typedef void (*cfi_check_fn)(uint64_t id, void *ptr, voi= d *diag); /* Compiler-generated function in each module, and the kernel */ extern void __cfi_check(uint64_t id, void *ptr, void *diag); =20 -/* - * Force the compiler to generate a CFI jump table entry for a function - * and store the jump table address to __cfi_jt_. - */ -#define __CFI_ADDRESSABLE(fn, __attr) \ - const void *__cfi_jt_ ## fn __visible __attr =3D (void *)&fn - -#else /* !CONFIG_CFI_CLANG */ - -#ifdef CONFIG_X86_KERNEL_IBT - -#define __CFI_ADDRESSABLE(fn, __attr) \ - const void *__cfi_jt_ ## fn __visible __attr =3D (void *)&fn - -#endif /* CONFIG_X86_KERNEL_IBT */ - #endif /* CONFIG_CFI_CLANG */ =20 -#ifndef __CFI_ADDRESSABLE -#define __CFI_ADDRESSABLE(fn, __attr) -#endif - #endif /* _LINUX_CFI_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 7713d7bcdaea..7bfafc69172a 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -221,9 +221,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f= , int val, * otherwise, or eliminated entirely due to lack of references that are * visible to the compiler. */ -#define __ADDRESSABLE(sym) \ - static void * __section(".discard.addressable") __used \ +#define ___ADDRESSABLE(sym, __attrs) \ + static void * __used __attrs \ __UNIQUE_ID(__PASTE(__addressable_,sym)) =3D (void *)&sym; +#define __ADDRESSABLE(sym) \ + ___ADDRESSABLE(sym, __section(".discard.addressable")) =20 /** * offset_to_ptr - convert a relative memory offset to an absolute pointer diff --git a/include/linux/module.h b/include/linux/module.h index 518296ea7f73..8937b020ec04 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -132,7 +132,7 @@ extern void cleanup_module(void); { return initfn; } \ int init_module(void) __copy(initfn) \ __attribute__((alias(#initfn))); \ - __CFI_ADDRESSABLE(init_module, __initdata); + ___ADDRESSABLE(init_module, __initdata); =20 /* This is only required if you want to be unloadable. */ #define module_exit(exitfn) \ @@ -140,7 +140,7 @@ extern void cleanup_module(void); { return exitfn; } \ void cleanup_module(void) __copy(exitfn) \ __attribute__((alias(#exitfn))); \ - __CFI_ADDRESSABLE(cleanup_module, __exitdata); + ___ADDRESSABLE(cleanup_module, __exitdata); =20 #endif =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD0F3ECAAA1 for ; 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Tue, 30 Aug 2022 16:31:46 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:13 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-6-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=15753; i=samitolvanen@google.com; h=from:subject; bh=kCPCwrWfKfR+47zuMRd+7NjMRv71MY29I1bZCtxLbxI=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3MrdViWUem/XBnu30YaMAfZydcXlgcbTrgLa+e jBt4PdWJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzAAKCRBMtfaEi7xW7umoC/ 49UVQV86/AuVPkPWkdVrVkEyDS/X6YCJh7gGxvdJkHW9pGZOxawDYIWlV42qbIKWbW/FO1ZEOXmtEv +6024VtQSVK+D75MltkNDV7Q68PJaWGvjSBCOZPdXupe76AUtLrNF2fDvUrcKhNbHIqQVI3gNYNmnb 61VrmRipFhfZZP36JbCxFSIQ8fSZz/o6wdm1WJNmCG7Am+vZEpPwhsbyI5YzO8stpkpyN5KCp02rxa oW7SmnGkROBEOVPKYFGgvuA9jqu7XmBISbEZeoaVehPFeAMa+9bR8XoNz85TD+4BGoTEuYjG4PL9Qm S5QfrWEKKhvdfW3A3/qZ9sDRMaFeGuNQP1a65S2iDzXwyCBXyHbkc1JMbrecqfU1UmyoCBECD1SLDe F2TJotemis8EYU4f/N1t70u/OJQi7ah3MSuSzdS865T8L8jIYWNHnMR8q3fQimrL6A4WN4/UvcMxqr MuCBFpmLi6jwn7Ht/KNck9FqME0wqqRetzAPUnaLFKfVA= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 05/21] cfi: Switch to -fsanitize=kcfi From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Switch from Clang's original forward-edge control-flow integrity implementation to -fsanitize=3Dkcfi, which is better suited for the kernel, as it doesn't require LTO, doesn't use a jump table that requires altering function references, and won't break cross-module function address equality. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- Makefile | 13 +-- arch/Kconfig | 8 +- include/asm-generic/vmlinux.lds.h | 37 ++++---- include/linux/cfi.h | 29 +++++- include/linux/compiler-clang.h | 14 +-- include/linux/module.h | 6 +- kernel/cfi.c | 144 +++++++++++++++--------------- kernel/module/main.c | 35 +------- scripts/module.lds.S | 23 +---- 9 files changed, 133 insertions(+), 176 deletions(-) diff --git a/Makefile b/Makefile index 952d354069a4..eec147f5572c 100644 --- a/Makefile +++ b/Makefile @@ -921,18 +921,7 @@ export CC_FLAGS_LTO endif =20 ifdef CONFIG_CFI_CLANG -CC_FLAGS_CFI :=3D -fsanitize=3Dcfi \ - -fsanitize-cfi-cross-dso \ - -fno-sanitize-cfi-canonical-jump-tables \ - -fno-sanitize-trap=3Dcfi \ - -fno-sanitize-blacklist - -ifdef CONFIG_CFI_PERMISSIVE -CC_FLAGS_CFI +=3D -fsanitize-recover=3Dcfi -endif - -# If LTO flags are filtered out, we must also filter out CFI. -CC_FLAGS_LTO +=3D $(CC_FLAGS_CFI) +CC_FLAGS_CFI :=3D -fsanitize=3Dkcfi KBUILD_CFLAGS +=3D $(CC_FLAGS_CFI) export CC_FLAGS_CFI endif diff --git a/arch/Kconfig b/arch/Kconfig index 5fd875e18c99..1c1eca0c0019 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -738,11 +738,13 @@ config ARCH_SUPPORTS_CFI_CLANG An architecture should select this option if it can support Clang's Control-Flow Integrity (CFI) checking. =20 +config ARCH_USES_CFI_TRAPS + bool + config CFI_CLANG bool "Use Clang's Control Flow Integrity (CFI)" - depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG - depends on CLANG_VERSION >=3D 140000 - select KALLSYMS + depends on ARCH_SUPPORTS_CFI_CLANG + depends on $(cc-option,-fsanitize=3Dkcfi) help This option enables Clang=E2=80=99s forward-edge Control Flow Integrity (CFI) checking, where the compiler injects a runtime check to each diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinu= x.lds.h index 7515a465ec03..7501edfce11e 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -421,6 +421,22 @@ __end_ro_after_init =3D .; #endif =20 +/* + * .kcfi_traps contains a list KCFI trap locations. + */ +#ifndef KCFI_TRAPS +#ifdef CONFIG_ARCH_USES_CFI_TRAPS +#define KCFI_TRAPS \ + __kcfi_traps : AT(ADDR(__kcfi_traps) - LOAD_OFFSET) { \ + __start___kcfi_traps =3D .; \ + KEEP(*(.kcfi_traps)) \ + __stop___kcfi_traps =3D .; \ + } +#else +#define KCFI_TRAPS +#endif +#endif + /* * Read only Data */ @@ -529,6 +545,8 @@ __stop___modver =3D .; \ } \ \ + KCFI_TRAPS \ + \ RO_EXCEPTION_TABLE \ NOTES \ BTF \ @@ -537,21 +555,6 @@ __end_rodata =3D .; =20 =20 -/* - * .text..L.cfi.jumptable.* contain Control-Flow Integrity (CFI) - * jump table entries. - */ -#ifdef CONFIG_CFI_CLANG -#define TEXT_CFI_JT \ - . =3D ALIGN(PMD_SIZE); \ - __cfi_jt_start =3D .; \ - *(.text..L.cfi.jumptable .text..L.cfi.jumptable.*) \ - . =3D ALIGN(PMD_SIZE); \ - __cfi_jt_end =3D .; -#else -#define TEXT_CFI_JT -#endif - /* * Non-instrumentable text section */ @@ -579,7 +582,6 @@ *(.text..refcount) \ *(.ref.text) \ *(.text.asan.* .text.tsan.*) \ - TEXT_CFI_JT \ MEM_KEEP(init.text*) \ MEM_KEEP(exit.text*) \ =20 @@ -1008,8 +1010,7 @@ * keep any .init_array.* sections. * https://bugs.llvm.org/show_bug.cgi?id=3D46478 */ -#if defined(CONFIG_GCOV_KERNEL) || defined(CONFIG_KASAN_GENERIC) || define= d(CONFIG_KCSAN) || \ - defined(CONFIG_CFI_CLANG) +#if defined(CONFIG_GCOV_KERNEL) || defined(CONFIG_KASAN_GENERIC) || define= d(CONFIG_KCSAN) # ifdef CONFIG_CONSTRUCTORS # define SANITIZER_DISCARDS \ *(.eh_frame) diff --git a/include/linux/cfi.h b/include/linux/cfi.h index 2cdbc0fbd0ab..5e134f4ce8b7 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -2,17 +2,38 @@ /* * Clang Control Flow Integrity (CFI) support. * - * Copyright (C) 2021 Google LLC + * Copyright (C) 2022 Google LLC */ #ifndef _LINUX_CFI_H #define _LINUX_CFI_H =20 +#include +#include + #ifdef CONFIG_CFI_CLANG -typedef void (*cfi_check_fn)(uint64_t id, void *ptr, void *diag); +enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long = addr, + unsigned long *target, u32 type); =20 -/* Compiler-generated function in each module, and the kernel */ -extern void __cfi_check(uint64_t id, void *ptr, void *diag); +static inline enum bug_trap_type report_cfi_failure_noaddr(struct pt_regs = *regs, + unsigned long addr) +{ + return report_cfi_failure(regs, addr, NULL, 0); +} =20 +#ifdef CONFIG_ARCH_USES_CFI_TRAPS +bool is_cfi_trap(unsigned long addr); +#endif #endif /* CONFIG_CFI_CLANG */ =20 +#ifdef CONFIG_MODULES +#ifdef CONFIG_ARCH_USES_CFI_TRAPS +void module_cfi_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, + struct module *mod); +#else +static inline void module_cfi_finalize(const Elf_Ehdr *hdr, + const Elf_Shdr *sechdrs, + struct module *mod) {} +#endif /* CONFIG_ARCH_USES_CFI_TRAPS */ +#endif /* CONFIG_MODULES */ + #endif /* _LINUX_CFI_H */ diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index c84fec767445..42e55579d649 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -66,17 +66,9 @@ # define __noscs __attribute__((__no_sanitize__("shadow-call-stack"))) #endif =20 -#define __nocfi __attribute__((__no_sanitize__("cfi"))) -#define __cficanonical __attribute__((__cfi_canonical_jump_table__)) - -#if defined(CONFIG_CFI_CLANG) -/* - * With CONFIG_CFI_CLANG, the compiler replaces function address - * references with the address of the function's CFI jump table - * entry. The function_nocfi macro always returns the address of the - * actual function instead. - */ -#define function_nocfi(x) __builtin_function_start(x) +#if __has_feature(kcfi) +/* Disable CFI checking inside a function. */ +#define __nocfi __attribute__((__no_sanitize__("kcfi"))) #endif =20 /* diff --git a/include/linux/module.h b/include/linux/module.h index 8937b020ec04..ec61fb53979a 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -27,7 +27,6 @@ #include #include #include -#include =20 #include #include @@ -387,8 +386,9 @@ struct module { const s32 *crcs; unsigned int num_syms; =20 -#ifdef CONFIG_CFI_CLANG - cfi_check_fn cfi_check; +#ifdef CONFIG_ARCH_USES_CFI_TRAPS + s32 *kcfi_traps; + s32 *kcfi_traps_end; #endif =20 /* Kernel parameters. */ diff --git a/kernel/cfi.c b/kernel/cfi.c index e8bc1b370edc..08caad776717 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -1,105 +1,101 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Clang Control Flow Integrity (CFI) error and slowpath handling. + * Clang Control Flow Integrity (CFI) error handling. * - * Copyright (C) 2021 Google LLC + * Copyright (C) 2022 Google LLC */ =20 -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -/* Compiler-defined handler names */ -#ifdef CONFIG_CFI_PERMISSIVE -#define cfi_failure_handler __ubsan_handle_cfi_check_fail -#else -#define cfi_failure_handler __ubsan_handle_cfi_check_fail_abort -#endif - -static inline void handle_cfi_failure(void *ptr) +#include + +enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long = addr, + unsigned long *target, u32 type) { - if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) - WARN_RATELIMIT(1, "CFI failure (target: %pS):\n", ptr); + if (target) + pr_err("CFI failure at %pS (target: %pS; expected type: 0x%08x)\n", + (void *)addr, (void *)*target, type); else - panic("CFI failure (target: %pS)\n", ptr); + pr_err("CFI failure at %pS (no target information)\n", + (void *)addr); + + if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) { + __warn(NULL, 0, (void *)addr, 0, regs, NULL); + return BUG_TRAP_TYPE_WARN; + } + + return BUG_TRAP_TYPE_BUG; } =20 -#ifdef CONFIG_MODULES +#ifdef CONFIG_ARCH_USES_CFI_TRAPS +static inline unsigned long trap_address(s32 *p) +{ + return (unsigned long)((long)p + (long)*p); +} =20 -static inline cfi_check_fn find_module_check_fn(unsigned long ptr) +static bool is_trap(unsigned long addr, s32 *start, s32 *end) { - cfi_check_fn fn =3D NULL; - struct module *mod; + s32 *p; =20 - rcu_read_lock_sched_notrace(); - mod =3D __module_address(ptr); - if (mod) - fn =3D mod->cfi_check; - rcu_read_unlock_sched_notrace(); + for (p =3D start; p < end; ++p) { + if (trap_address(p) =3D=3D addr) + return true; + } =20 - return fn; + return false; } =20 -static inline cfi_check_fn find_check_fn(unsigned long ptr) +#ifdef CONFIG_MODULES +/* Populates `kcfi_trap(_end)?` fields in `struct module`. */ +void module_cfi_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, + struct module *mod) { - cfi_check_fn fn =3D NULL; - unsigned long flags; - bool rcu_idle; - - if (is_kernel_text(ptr)) - return __cfi_check; - - /* - * Indirect call checks can happen when RCU is not watching. Both - * the shadow and __module_address use RCU, so we need to wake it - * up if necessary. - */ - rcu_idle =3D !rcu_is_watching(); - if (rcu_idle) { - local_irq_save(flags); - ct_irq_enter(); - } + char *secstrings; + unsigned int i; =20 - fn =3D find_module_check_fn(ptr); + mod->kcfi_traps =3D NULL; + mod->kcfi_traps_end =3D NULL; =20 - if (rcu_idle) { - ct_irq_exit(); - local_irq_restore(flags); - } + secstrings =3D (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; + + for (i =3D 1; i < hdr->e_shnum; i++) { + if (strcmp(secstrings + sechdrs[i].sh_name, "__kcfi_traps")) + continue; =20 - return fn; + mod->kcfi_traps =3D (s32 *)sechdrs[i].sh_addr; + mod->kcfi_traps_end =3D (s32 *)(sechdrs[i].sh_addr + sechdrs[i].sh_size); + break; + } } =20 -void __cfi_slowpath_diag(uint64_t id, void *ptr, void *diag) +static bool is_module_cfi_trap(unsigned long addr) { - cfi_check_fn fn =3D find_check_fn((unsigned long)ptr); + struct module *mod; + bool found =3D false; =20 - if (likely(fn)) - fn(id, ptr, diag); - else /* Don't allow unchecked modules */ - handle_cfi_failure(ptr); -} -EXPORT_SYMBOL(__cfi_slowpath_diag); + rcu_read_lock_sched_notrace(); =20 -#else /* !CONFIG_MODULES */ + mod =3D __module_address(addr); + if (mod) + found =3D is_trap(addr, mod->kcfi_traps, mod->kcfi_traps_end); =20 -void __cfi_slowpath_diag(uint64_t id, void *ptr, void *diag) + rcu_read_unlock_sched_notrace(); + + return found; +} +#else /* CONFIG_MODULES */ +static inline bool is_module_cfi_trap(unsigned long addr) { - handle_cfi_failure(ptr); /* No modules */ + return false; } -EXPORT_SYMBOL(__cfi_slowpath_diag); - #endif /* CONFIG_MODULES */ =20 -void cfi_failure_handler(void *data, void *ptr, void *vtable) +extern s32 __start___kcfi_traps[]; +extern s32 __stop___kcfi_traps[]; + +bool is_cfi_trap(unsigned long addr) { - handle_cfi_failure(ptr); + if (is_trap(addr, __start___kcfi_traps, __stop___kcfi_traps)) + return true; + + return is_module_cfi_trap(addr); } -EXPORT_SYMBOL(cfi_failure_handler); +#endif /* CONFIG_ARCH_USES_CFI_TRAPS */ diff --git a/kernel/module/main.c b/kernel/module/main.c index 0228f44b58e5..70c0b2c6fef8 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -53,6 +53,7 @@ #include #include #include +#include #include #include "internal.h" =20 @@ -2597,8 +2598,9 @@ static int complete_formation(struct module *mod, str= uct load_info *info) if (err < 0) goto out; =20 - /* This relies on module_mutex for list integrity. */ + /* These rely on module_mutex for list integrity. */ module_bug_finalize(info->hdr, info->sechdrs, mod); + module_cfi_finalize(info->hdr, info->sechdrs, mod); =20 if (module_check_misalignment(mod)) goto out_misaligned; @@ -2660,8 +2662,6 @@ static int unknown_module_param_cb(char *param, char = *val, const char *modname, return 0; } =20 -static void cfi_init(struct module *mod); - /* * Allocate and load the module: note that size of section 0 is always * zero, and we rely on this for optional sections. @@ -2791,9 +2791,6 @@ static int load_module(struct load_info *info, const = char __user *uargs, =20 flush_module_icache(mod); =20 - /* Setup CFI for the module. */ - cfi_init(mod); - /* Now copy in args */ mod->args =3D strndup_user(uargs, ~0UL >> 1); if (IS_ERR(mod->args)) { @@ -2955,32 +2952,6 @@ static inline int within(unsigned long addr, void *s= tart, unsigned long size) return ((void *)addr >=3D start && (void *)addr < start + size); } =20 -static void cfi_init(struct module *mod) -{ -#ifdef CONFIG_CFI_CLANG - initcall_t *init; -#ifdef CONFIG_MODULE_UNLOAD - exitcall_t *exit; -#endif - - rcu_read_lock_sched(); - mod->cfi_check =3D (cfi_check_fn) - find_kallsyms_symbol_value(mod, "__cfi_check"); - init =3D (initcall_t *) - find_kallsyms_symbol_value(mod, "__cfi_jt_init_module"); - /* Fix init/exit functions to point to the CFI jump table */ - if (init) - mod->init =3D *init; -#ifdef CONFIG_MODULE_UNLOAD - exit =3D (exitcall_t *) - find_kallsyms_symbol_value(mod, "__cfi_jt_cleanup_module"); - if (exit) - mod->exit =3D *exit; -#endif - rcu_read_unlock_sched(); -#endif -} - /* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */ char *module_flags(struct module *mod, char *buf, bool show_state) { diff --git a/scripts/module.lds.S b/scripts/module.lds.S index 3a3aa2354ed8..da4bddd26171 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -3,20 +3,10 @@ * Archs are free to supply their own linker scripts. ld will * combine them automatically. */ -#ifdef CONFIG_CFI_CLANG -# include -# define ALIGN_CFI ALIGN(PAGE_SIZE) -# define SANITIZER_DISCARDS *(.eh_frame) -#else -# define ALIGN_CFI -# define SANITIZER_DISCARDS -#endif - SECTIONS { /DISCARD/ : { *(.discard) *(.discard.*) - SANITIZER_DISCARDS } =20 __ksymtab 0 : { *(SORT(___ksymtab+*)) } @@ -33,6 +23,10 @@ SECTIONS { =20 __patchable_function_entries : { *(__patchable_function_entries) } =20 +#ifdef CONFIG_ARCH_USES_CFI_TRAPS + __kcfi_traps : { KEEP(*(.kcfi_traps)) } +#endif + #ifdef CONFIG_LTO_CLANG /* * With CONFIG_LTO_CLANG, LLD always enables -fdata-sections and @@ -53,15 +47,6 @@ SECTIONS { *(.rodata .rodata.[0-9a-zA-Z_]*) *(.rodata..L*) } - - /* - * With CONFIG_CFI_CLANG, we assume __cfi_check is at the beginning - * of the .text section, and is aligned to PAGE_SIZE. - */ - .text : ALIGN_CFI { - *(.text.__cfi_check) - *(.text .text.[0-9a-zA-Z_]* .text..L.cfi*) - } #endif } =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C410ECAAD5 for ; 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Tue, 30 Aug 2022 16:31:49 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:14 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-7-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=3855; i=samitolvanen@google.com; h=from:subject; bh=GpNP7VSNWEHryZQIbE63CWLGUtZrRNNHgFNGIsCcLD4=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3M+D27Vh42dz5Wv1D7BtVLA+c02bXPeMllsUQG nbALH5eJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzAAKCRBMtfaEi7xW7oO6C/ 94PkporT0a7ea4yN99Y0UVpECqA2sx1W3i2E3Ta36aou4DLUlkkK11bJAHilB90A47YnMhOyD+xQgt qKKB3pKeDH8pGEOLtNrtnEcXa8Crfg92HjaovTQVUu0/EZPE04ME54eNDEPYc3a+V4i5acQbwfayOD B0FHeJLg7YmKTXdSQw1OCZqJmfO723qcQ/XI/eRxbqrZQyEVq3N662FBhRI1BZwJyxJGUKVFjALx7E W60FTV25BYf9dy7O8xvh++ELkTTfrKeFtMnwnAfkOl9A6vmx9T8d7OAI7sBn0/8K3nzWRQuWYrqV66 mjnnzUqYPDcgxJBn9EC2aNqti/tAGgC6PtM1uERqT1VdgPrWwYG246O0IZM1z5wznrj1DnlrMmT0+a mBAL9oB8jrEBtQ/SRxdAZbh+LkXmAx2XKKBltPHK3GvAUGxPGlOLjFBMbKvbSO3jtAV3m2OqXpjGF0 td+Ah0KUqN8vnfBbB9WQZO9fsTb6Obx8Mpa2GsG77Z11w= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 06/21] cfi: Add type helper macros From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" With CONFIG_CFI_CLANG, assembly functions called indirectly from C code must be annotated with type identifiers to pass CFI checking. In order to make this easier, the compiler emits a __kcfi_typeid_ symbol for each address-taken function declaration in C, which contains the expected type identifier that we can refer to in assembly code. Add typed versions of SYM_FUNC_START and SYM_FUNC_START_ALIAS, which emit the type identifier before the function. Architectures that support KCFI can define their own __CFI_TYPE macro to override the default preamble format. As an example, for the x86_64 blowfish_dec_blk function, the compiler emits the following type symbol: $ readelf -sW vmlinux | grep __kcfi_typeid_blowfish_dec_blk 121794: ffffffffef478db5 0 NOTYPE WEAK DEFAULT ABS __kcfi_typeid_blowfish_dec_blk And SYM_FUNC_START will generate the following preamble based on the __CFI_TYPE definition for the architecture: $ objdump -dr arch/x86/crypto/blowfish-x86_64-asm_64.o ... 00000000000003f7 <__cfi_blowfish_dec_blk>: 3f7: cc int3 3f8: cc int3 3f9: 8b 04 25 00 00 00 00 mov 0x0,%eax 3fc: R_X86_64_32S __kcfi_typeid_blowfish_dec_blk 400: cc int3 401: cc int3 0000000000000402 : ... Note that the address of all assembly functions annotated with SYM_FUNC_START* must be taken in C code that's linked into the binary or the missing __kcfi_typeid_ symbol will result in a linker error with CONFIG_CFI_CLANG. If the code that contains the indirect call is not always compiled in, __ADDRESSABLE(functionname) can be used to ensure that the __kcfi_typeid_ symbol is emitted. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- include/linux/cfi_types.h | 57 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 include/linux/cfi_types.h diff --git a/include/linux/cfi_types.h b/include/linux/cfi_types.h new file mode 100644 index 000000000000..dd16e755a197 --- /dev/null +++ b/include/linux/cfi_types.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Clang Control Flow Integrity (CFI) type definitions. + */ +#ifndef _LINUX_CFI_TYPES_H +#define _LINUX_CFI_TYPES_H + +#ifdef CONFIG_CFI_CLANG +#include + +#ifdef __ASSEMBLY__ +/* + * Use the __kcfi_typeid_ type identifier symbol to + * annotate indirectly called assembly functions. The compiler emits + * these symbols for all address-taken function declarations in C + * code. + */ +#ifndef __CFI_TYPE +#define __CFI_TYPE(name) \ + .4byte __kcfi_typeid_##name +#endif + +#define SYM_TYPED_ENTRY(name, fname, linkage, align...) \ + linkage(name) ASM_NL \ + align ASM_NL \ + __CFI_TYPE(fname) ASM_NL \ + name: + +#define __SYM_TYPED_FUNC_START_ALIAS(name, fname) \ + SYM_TYPED_ENTRY(name, fname, SYM_L_GLOBAL, SYM_A_ALIGN) + +#define __SYM_TYPED_FUNC_START(name, fname) \ + SYM_TYPED_ENTRY(name, fname, SYM_L_GLOBAL, SYM_A_ALIGN) + +#endif /* __ASSEMBLY__ */ + +#else /* CONFIG_CFI_CLANG */ + +#ifdef __ASSEMBLY__ +#define __SYM_TYPED_FUNC_START_ALIAS(name, fname) \ + SYM_FUNC_START_ALIAS(name) + +#define __SYM_TYPED_FUNC_START(name, fname) \ + SYM_FUNC_START(name) +#endif /* __ASSEMBLY__ */ + +#endif /* CONFIG_CFI_CLANG */ + +#ifdef __ASSEMBLY__ +#define SYM_TYPED_FUNC_START_ALIAS(name) \ + __SYM_TYPED_FUNC_START_ALIAS(name, name) + +#define SYM_TYPED_FUNC_START(name) \ + __SYM_TYPED_FUNC_START(name, name) +#endif /* __ASSEMBLY__ */ + +#endif /* _LINUX_CFI_TYPES_H */ --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1D10ECAAD4 for ; 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Tue, 30 Aug 2022 16:31:52 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:15 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=1674; i=samitolvanen@google.com; h=from:subject; bh=qxVnlSZocW9/1UypXlLGEHXfm4CDzclNhcl/lJ18fGo=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3M7+6Z3E3yWx3lSnRphzF4/3RQHI2psdANcTX1 DniQSb2JAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzAAKCRBMtfaEi7xW7vYpC/ wJyHxmthaRukbl+m+7vClm87xKX81E51zW8v/dmnTAiBQ7oT1Ek1XR7SJo/50PfceCBcZ366Psr6wx L7143nIwKv3bXT4p97cRjwxu4M0m8HvXeZYxX2Xqsc6uerduxtDTzFjDPWA8VsVsVXpIN5BluFq//1 Jx120TP9+6zYwQsOBpMcJCq2cr+LMVUG0pX2qqLSJGAE1+2yoL2kBisWcIdDxS1jJ5266S/HoYqktz JO/BzYSjJqxWmTxt2M4SzxDHm1EgNjsm5ntVO+KRW+klcvF2/1A+hyopJ1c+SrByL7fc/WNq8q15Gu rS6sXoG21TAT7q0EBWR2GYae6G6d/o1Sn1DTQpzi+TfRj8zYXkDPGgdxdflelIoodZ3g3q/vf2hzCC Y6S35Cpa4ek9uS8PsTuYFkYecoZCw/xrq+x1R6KPGpwl3/NAuYPWxv8goJ10UY0hjOxJby0LDXRouv cp8+PZmKAqFAjGeoHcRcLyUkHJSTY52q00bcKiCKHOdz8= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 07/21] lkdtm: Emit an indirect call for CFI tests From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Clang can convert the indirect calls in lkdtm_CFI_FORWARD_PROTO into direct calls. Move the call into a noinline function that accepts the target address as an argument to ensure the compiler actually emits an indirect call instead. Signed-off-by: Sami Tolvanen Reviewed-by: Nick Desaulniers Acked-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- drivers/misc/lkdtm/cfi.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c index 71483cb1e422..5245cf6013c9 100644 --- a/drivers/misc/lkdtm/cfi.c +++ b/drivers/misc/lkdtm/cfi.c @@ -20,6 +20,13 @@ static noinline int lkdtm_increment_int(int *counter) =20 return *counter; } + +/* Don't allow the compiler to inline the calls. */ +static noinline void lkdtm_indirect_call(void (*func)(int *)) +{ + func(&called_count); +} + /* * This tries to call an indirect function with a mismatched prototype. */ @@ -29,15 +36,11 @@ static void lkdtm_CFI_FORWARD_PROTO(void) * Matches lkdtm_increment_void()'s prototype, but not * lkdtm_increment_int()'s prototype. */ - void (*func)(int *); - pr_info("Calling matched prototype ...\n"); - func =3D lkdtm_increment_void; - func(&called_count); + lkdtm_indirect_call(lkdtm_increment_void); =20 pr_info("Calling mismatched prototype ...\n"); - func =3D (void *)lkdtm_increment_int; - func(&called_count); + lkdtm_indirect_call((void *)lkdtm_increment_int); =20 pr_err("FAIL: survived mismatched prototype function call!\n"); pr_expected_config(CONFIG_CFI_CLANG); --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22EB3ECAAA1 for ; Tue, 30 Aug 2022 23:32:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232079AbiH3Xcv (ORCPT ); Tue, 30 Aug 2022 19:32:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231819AbiH3XcG (ORCPT ); Tue, 30 Aug 2022 19:32:06 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D11D272EFA for ; 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a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=1663; i=samitolvanen@google.com; h=from:subject; bh=dCgTAVpHmh6ue+qIjFQmdwGO+wJHDxTFzsMUhw9fLMU=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3NvhTqxF6HKWPsUGSSA+N2dkmpL8jOb0ZK7Jx1 pV8vgQyJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzQAKCRBMtfaEi7xW7kFoC/ 9rUzKXMDXQKoSguu/A2Rv2ATA5t4yfg6zrdjYpiicpnCS+TbGGK2lUdzlcslHdS1IDP2ecHOWcdDcl Fe0QHSu2ujICLA210WhZwuUleMLIwtCzQDdoDj1VPjBfrJ3m8Bvw8UoVtabPRz2Up91t3EszVWpke7 cOKRhf1TZUreP9c5HzmehuN6xPi6PfCsXekOiqqKS5bveLFNH1izxbSyDg4MB/Nf67NMlQonGdnxzl vhT5ncb1Xb0rn50pB1LcJRz/YZ8D3+Y3Vc5j3XBWHUj6N3RIJOxyEXC5ypoF774b2i+O7fvWy20CPQ hFIEux/rXEdv28MYbGssuPw+fLT/IhlbUoI1f+MxSCobNzG5kQcxThpkupoA9NFbFWxmBatG+FcPc8 WTSgP0bNGyxHqO6BkyENMKnpUsvQbWes5XHGgvDop67nvldrkisGMHpuaEXqz3dQ99BgFp035sdyOc zEqaAajdW2W/J6ScBKCLnWsAcMP9axCky8DTM7nWY/lBE= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 08/21] psci: Fix the function type for psci_initcall_t From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Functions called through a psci_initcall_t pointer all have non-const arguments. Fix the type definition to avoid tripping indirect call checks with CFI_CLANG. Suggested-by: Mark Rutland Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- drivers/firmware/psci/psci.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c index cfb448eabdaa..75ef784a3789 100644 --- a/drivers/firmware/psci/psci.c +++ b/drivers/firmware/psci/psci.c @@ -274,7 +274,7 @@ static void set_conduit(enum arm_smccc_conduit conduit) psci_conduit =3D conduit; } =20 -static int get_set_conduit_method(struct device_node *np) +static int get_set_conduit_method(const struct device_node *np) { const char *method; =20 @@ -528,7 +528,7 @@ typedef int (*psci_initcall_t)(const struct device_node= *); * * Probe based on PSCI PSCI_VERSION function */ -static int __init psci_0_2_init(struct device_node *np) +static int __init psci_0_2_init(const struct device_node *np) { int err; =20 @@ -549,7 +549,7 @@ static int __init psci_0_2_init(struct device_node *np) /* * PSCI < v0.2 get PSCI Function IDs via DT. */ -static int __init psci_0_1_init(struct device_node *np) +static int __init psci_0_1_init(const struct device_node *np) { u32 id; int err; @@ -585,7 +585,7 @@ static int __init psci_0_1_init(struct device_node *np) return 0; } =20 -static int __init psci_1_0_init(struct device_node *np) +static int __init psci_1_0_init(const struct device_node *np) { int err; =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C698C3DA6B for ; Tue, 30 Aug 2022 23:32:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231487AbiH3Xcy (ORCPT ); Tue, 30 Aug 2022 19:32:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232066AbiH3XcG (ORCPT ); Tue, 30 Aug 2022 19:32:06 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D8687330D for ; 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charset="utf-8" With CONFIG_CFI_CLANG, assembly functions indirectly called from C code must be annotated with type identifiers to pass CFI checking. Use SYM_TYPED_FUNC_START for the indirectly called functions. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/arm64/crypto/ghash-ce-core.S | 5 +++-- arch/arm64/crypto/sm3-ce-core.S | 3 ++- arch/arm64/kernel/cpu-reset.S | 5 +++-- arch/arm64/mm/proc.S | 5 +++-- 4 files changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/arm64/crypto/ghash-ce-core.S b/arch/arm64/crypto/ghash-ce= -core.S index 7868330dd54e..ebe5558929b7 100644 --- a/arch/arm64/crypto/ghash-ce-core.S +++ b/arch/arm64/crypto/ghash-ce-core.S @@ -6,6 +6,7 @@ */ =20 #include +#include #include =20 SHASH .req v0 @@ -350,11 +351,11 @@ CPU_LE( rev64 T1.16b, T1.16b ) * void pmull_ghash_update(int blocks, u64 dg[], const char *src, * struct ghash_key const *k, const char *head) */ -SYM_FUNC_START(pmull_ghash_update_p64) +SYM_TYPED_FUNC_START(pmull_ghash_update_p64) __pmull_ghash p64 SYM_FUNC_END(pmull_ghash_update_p64) =20 -SYM_FUNC_START(pmull_ghash_update_p8) +SYM_TYPED_FUNC_START(pmull_ghash_update_p8) __pmull_ghash p8 SYM_FUNC_END(pmull_ghash_update_p8) =20 diff --git a/arch/arm64/crypto/sm3-ce-core.S b/arch/arm64/crypto/sm3-ce-cor= e.S index ef97d3187cb7..ca70cfacd0d0 100644 --- a/arch/arm64/crypto/sm3-ce-core.S +++ b/arch/arm64/crypto/sm3-ce-core.S @@ -6,6 +6,7 @@ */ =20 #include +#include #include =20 .irp b, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 @@ -73,7 +74,7 @@ * int blocks) */ .text -SYM_FUNC_START(sm3_ce_transform) +SYM_TYPED_FUNC_START(sm3_ce_transform) /* load state */ ld1 {v8.4s-v9.4s}, [x0] rev64 v8.4s, v8.4s diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S index 48a8af97faa9..6b752fe89745 100644 --- a/arch/arm64/kernel/cpu-reset.S +++ b/arch/arm64/kernel/cpu-reset.S @@ -8,6 +8,7 @@ */ =20 #include +#include #include #include #include @@ -28,7 +29,7 @@ * branch to what would be the reset vector. It must be executed with the * flat identity mapping. */ -SYM_CODE_START(cpu_soft_restart) +SYM_TYPED_FUNC_START(cpu_soft_restart) mov_q x12, INIT_SCTLR_EL1_MMU_OFF pre_disable_mmu_workaround /* @@ -47,6 +48,6 @@ SYM_CODE_START(cpu_soft_restart) mov x1, x3 // arg1 mov x2, x4 // arg2 br x8 -SYM_CODE_END(cpu_soft_restart) +SYM_FUNC_END(cpu_soft_restart) =20 .popsection diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 7837a69524c5..8b9f419fcad9 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -185,7 +186,7 @@ SYM_FUNC_END(cpu_do_resume) * This is the low-level counterpart to cpu_replace_ttbr1, and should not = be * called by anything else. It can only be executed from a TTBR0 mapping. */ -SYM_FUNC_START(idmap_cpu_replace_ttbr1) +SYM_TYPED_FUNC_START(idmap_cpu_replace_ttbr1) save_and_disable_daif flags=3Dx2 =20 __idmap_cpu_set_reserved_ttbr1 x1, x3 @@ -253,7 +254,7 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1) SYM_DATA(__idmap_kpti_flag, .long 1) .popsection =20 -SYM_FUNC_START(idmap_kpti_install_ng_mappings) +SYM_TYPED_FUNC_START(idmap_kpti_install_ng_mappings) cpu .req w0 temp_pte .req x0 num_cpus .req w1 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D62FECAAD4 for ; Tue, 30 Aug 2022 23:33:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232327AbiH3Xc6 (ORCPT ); Tue, 30 Aug 2022 19:32:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231941AbiH3XcI (ORCPT ); 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Tue, 30 Aug 2022 16:32:00 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:18 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-11-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=6529; i=samitolvanen@google.com; h=from:subject; bh=nax/A443rh70RgFtHDBePJR2kdPLcGN3ANa3NK4sLi8=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3NK1Z21u8OhRuM2jehM3T+7tCoihG4K4pRyvz7 OkhRsH6JAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzQAKCRBMtfaEi7xW7i94C/ 97cAZRVEO58C0yxsqxcjc52SnV0Q3pdCtoAixUtA2bkV68T2uBNfNz5YWatziNJlUDvsL6JgHGx1fo 9RuZHIvtx3o9OGO6wTG7Vnrm2yRlwBYD1H7GxD9XFn8onBGGA9Wn/u+btijUxyPaDKRqm7kiiZMUBV JgtHzTVCp1ORfJxxfbnrzxkN33JefyJwz+V9rnSx4w/Zko0s1CovjwzoWhYYQyx9smbXsW704bRnWE j2mI/qzGiHQTarDyRtR+gfjXFPLIFLmxiLLMNPQgZCBuNcmbHMnuN5cPrfEsZ8gOqB9V/uoQmseQev nXx6hwxdy4nWzyKYl0ylTpJBC0IbzUUnFQJqsepJS8sVdpmoplvPgX+FeyCbld30TJSm7IDOSwMYPM QsjftdSaOo6CRXP2ezJh6Ndzgx+FF9sZoEO0DeWuLVanjx+InxI7QCBiPUJb94OxRsRgYRwhkLL3KE 9+hIOnieKNzQKrAzNHaNN/jbkXiz7/4y6Mu2RzMMPJrNw= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 10/21] arm64: Add CFI error handling From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" With -fsanitize=3Dkcfi, CFI always traps. Add arm64 support for handling CFI failures. The registers containing the target address and the expected type are encoded in the first ten bits of the ESR as follows: - 0-4: n, where the register Xn contains the target address - 5-9: m, where the register Wm contains the type hash This produces the following oops on CFI failure (generated using lkdtm): [ 21.885179] CFI failure at lkdtm_indirect_call+0x2c/0x44 [lkdtm] (target: lkdtm_increment_int+0x0/0x1c [lkdtm]; expected type: 0x7e0c52a) [ 21.886593] Internal error: Oops - CFI: 0 [#1] PREEMPT SMP [ 21.891060] Modules linked in: lkdtm [ 21.893363] CPU: 0 PID: 151 Comm: sh Not tainted 5.19.0-rc1-00021-g852f4e48dbab #1 [ 21.895560] Hardware name: linux,dummy-virt (DT) [ 21.896543] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE= =3D--) [ 21.897583] pc : lkdtm_indirect_call+0x2c/0x44 [lkdtm] [ 21.898551] lr : lkdtm_CFI_FORWARD_PROTO+0x3c/0x6c [lkdtm] [ 21.899520] sp : ffff8000083a3c50 [ 21.900191] x29: ffff8000083a3c50 x28: ffff0000027e0ec0 x27: 00000000000= 00000 [ 21.902453] x26: 0000000000000000 x25: ffffc2aa3d07e7b0 x24: 00000000000= 00002 [ 21.903736] x23: ffffc2aa3d079088 x22: ffffc2aa3d07e7b0 x21: ffff0000033= 79000 [ 21.905062] x20: ffff8000083a3dc0 x19: 0000000000000012 x18: 00000000000= 00000 [ 21.906371] x17: 000000007e0c52a5 x16: 000000003ad55aca x15: ffffc2aa60d= 92138 [ 21.907662] x14: ffffffffffffffff x13: 2e2e2e2065707974 x12: 00000000000= 00018 [ 21.909775] x11: ffffc2aa62322b88 x10: ffffc2aa62322aa0 x9 : c7e305fb519= 5d200 [ 21.911898] x8 : ffffc2aa3d077e20 x7 : 6d20676e696c6c61 x6 : 43203a6d746= 46b6c [ 21.913108] x5 : ffffc2aa6266c9df x4 : ffffc2aa6266c9e1 x3 : ffff8000083= a3968 [ 21.914358] x2 : 80000000fffff122 x1 : 00000000fffff122 x0 : ffffc2aa3d0= 7e8f8 [ 21.915827] Call trace: [ 21.916375] lkdtm_indirect_call+0x2c/0x44 [lkdtm] [ 21.918060] lkdtm_CFI_FORWARD_PROTO+0x3c/0x6c [lkdtm] [ 21.919030] lkdtm_do_action+0x34/0x4c [lkdtm] [ 21.919920] direct_entry+0x170/0x1ac [lkdtm] [ 21.920772] full_proxy_write+0x84/0x104 [ 21.921759] vfs_write+0x188/0x3d8 [ 21.922387] ksys_write+0x78/0xe8 [ 21.922986] __arm64_sys_write+0x1c/0x2c [ 21.923696] invoke_syscall+0x58/0x134 [ 21.924554] el0_svc_common+0xb4/0xf4 [ 21.925603] do_el0_svc+0x2c/0xb4 [ 21.926563] el0_svc+0x2c/0x7c [ 21.927147] el0t_64_sync_handler+0x84/0xf0 [ 21.927985] el0t_64_sync+0x18c/0x190 [ 21.929133] Code: 728a54b1 72afc191 6b11021f 54000040 (d4304500) [ 21.930690] ---[ end trace 0000000000000000 ]--- [ 21.930971] Kernel panic - not syncing: Oops - CFI: Fatal exception Suggested-by: Mark Rutland Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/arm64/include/asm/brk-imm.h | 6 ++++ arch/arm64/kernel/traps.c | 47 ++++++++++++++++++++++++++++++-- 2 files changed, 50 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-= imm.h index ec7720dbe2c8..6e000113e508 100644 --- a/arch/arm64/include/asm/brk-imm.h +++ b/arch/arm64/include/asm/brk-imm.h @@ -17,6 +17,7 @@ * 0x401: for compile time BRK instruction * 0x800: kernel-mode BUG() and WARN() traps * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff) + * 0x8xxx: Control-Flow Integrity traps */ #define KPROBES_BRK_IMM 0x004 #define UPROBES_BRK_IMM 0x005 @@ -28,4 +29,9 @@ #define KASAN_BRK_IMM 0x900 #define KASAN_BRK_MASK 0x0ff =20 +#define CFI_BRK_IMM_TARGET GENMASK(4, 0) +#define CFI_BRK_IMM_TYPE GENMASK(9, 5) +#define CFI_BRK_IMM_BASE 0x8000 +#define CFI_BRK_IMM_MASK (CFI_BRK_IMM_TARGET | CFI_BRK_IMM_TYPE) + #endif diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index b7fed33981f7..3c026da95bbc 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -26,6 +26,7 @@ #include #include #include +#include =20 #include #include @@ -991,6 +992,38 @@ static struct break_hook bug_break_hook =3D { .imm =3D BUG_BRK_IMM, }; =20 +#ifdef CONFIG_CFI_CLANG +static int cfi_handler(struct pt_regs *regs, unsigned long esr) +{ + unsigned long target; + u32 type; + + target =3D pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TARGET, esr)); + type =3D (u32)pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TYPE, esr)); + + switch (report_cfi_failure(regs, regs->pc, &target, type)) { + case BUG_TRAP_TYPE_BUG: + die("Oops - CFI", regs, 0); + break; + + case BUG_TRAP_TYPE_WARN: + break; + + default: + return DBG_HOOK_ERROR; + } + + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); + return DBG_HOOK_HANDLED; +} + +static struct break_hook cfi_break_hook =3D { + .fn =3D cfi_handler, + .imm =3D CFI_BRK_IMM_BASE, + .mask =3D CFI_BRK_IMM_MASK, +}; +#endif /* CONFIG_CFI_CLANG */ + static int reserved_fault_handler(struct pt_regs *regs, unsigned long esr) { pr_err("%s generated an invalid instruction at %pS!\n", @@ -1052,6 +1085,9 @@ static struct break_hook kasan_break_hook =3D { }; #endif =20 + +#define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) + /* * Initial handler for AArch64 BRK exceptions * This handler only used until debug_traps_init(). @@ -1059,10 +1095,12 @@ static struct break_hook kasan_break_hook =3D { int __init early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs) { +#ifdef CONFIG_CFI_CLANG + if ((esr_comment(esr) & ~CFI_BRK_IMM_MASK) =3D=3D CFI_BRK_IMM_BASE) + return cfi_handler(regs, esr) !=3D DBG_HOOK_HANDLED; +#endif #ifdef CONFIG_KASAN_SW_TAGS - unsigned long comment =3D esr & ESR_ELx_BRK64_ISS_COMMENT_MASK; - - if ((comment & ~KASAN_BRK_MASK) =3D=3D KASAN_BRK_IMM) + if ((esr_comment(esr) & ~KASAN_BRK_MASK) =3D=3D KASAN_BRK_IMM) return kasan_handler(regs, esr) !=3D DBG_HOOK_HANDLED; #endif return bug_handler(regs, esr) !=3D DBG_HOOK_HANDLED; @@ -1071,6 +1109,9 @@ int __init early_brk64(unsigned long addr, unsigned l= ong esr, void __init trap_init(void) { register_kernel_break_hook(&bug_break_hook); +#ifdef CONFIG_CFI_CLANG + register_kernel_break_hook(&cfi_break_hook); +#endif register_kernel_break_hook(&fault_break_hook); #ifdef CONFIG_KASAN_SW_TAGS register_kernel_break_hook(&kasan_break_hook); --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C579CECAAD4 for ; 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charset="utf-8" With -fsanitize=3Dkcfi, CONFIG_CFI_CLANG no longer has issues with address space confusion in functions that switch to linear mapping. Now that the indirectly called assembly functions have type annotations, drop the __nocfi attributes. Suggested-by: Mark Rutland Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/arm64/include/asm/mmu_context.h | 2 +- arch/arm64/kernel/alternative.c | 2 +- arch/arm64/kernel/cpufeature.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/= mmu_context.h index c7ccd82db1d2..bba0e630c8bc 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -147,7 +147,7 @@ static inline void cpu_install_ttbr0(phys_addr_t ttbr0,= unsigned long t0sz) * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible P= GD, * avoiding the possibility of conflicting TLB entries being allocated. */ -static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap) +static inline void cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap) { typedef void (ttbr_replace_func)(phys_addr_t); extern ttbr_replace_func idmap_cpu_replace_ttbr1; diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternativ= e.c index 9bcaa5eacf16..d2c66507398d 100644 --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -133,7 +133,7 @@ static void clean_dcache_range_nopatch(u64 start, u64 e= nd) } while (cur +=3D d_size, cur < end); } =20 -static void __nocfi __apply_alternatives(struct alt_region *region, bool i= s_module, +static void __apply_alternatives(struct alt_region *region, bool is_module, unsigned long *feature_mask) { struct alt_instr *alt; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index af4de817d712..ca6e5ca7104e 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1685,7 +1685,7 @@ static phys_addr_t kpti_ng_pgd_alloc(int shift) return kpti_ng_temp_alloc; } =20 -static void __nocfi +static void kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) { typedef void (kpti_remap_fn)(int, int, phys_addr_t, unsigned long); 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charset="utf-8" It's no longer necessary to disable CFI checking for all __init functions. Drop the __nocfi attribute from __init. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- include/linux/init.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/init.h b/include/linux/init.h index baf0b29a7010..88f2964097f5 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -47,7 +47,7 @@ =20 /* These are for everybody (although not all archs will actually discard it in modules) */ -#define __init __section(".init.text") __cold __latent_entropy __noinitr= etpoline __nocfi +#define __init __section(".init.text") __cold __latent_entropy __noinitr= etpoline #define __initdata __section(".init.data") #define __initconst __section(".init.rodata") #define __exitdata __section(".exit.data") --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7696AECAAD5 for ; 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charset="utf-8" With -fsanitize=3Dkcfi, we no longer need function_nocfi() as the compiler won't change function references to point to a jump table. Remove all implementations and uses of the macro. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/arm64/include/asm/ftrace.h | 2 +- arch/arm64/include/asm/mmu_context.h | 2 +- arch/arm64/kernel/acpi_parking_protocol.c | 2 +- arch/arm64/kernel/cpufeature.c | 2 +- arch/arm64/kernel/ftrace.c | 2 +- arch/arm64/kernel/machine_kexec.c | 2 +- arch/arm64/kernel/psci.c | 2 +- arch/arm64/kernel/smp_spin_table.c | 2 +- drivers/firmware/psci/psci.c | 4 ++-- drivers/misc/lkdtm/usercopy.c | 2 +- include/linux/compiler.h | 10 ---------- 11 files changed, 11 insertions(+), 21 deletions(-) diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrac= e.h index dbc45a4157fa..329dbbd4d50b 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -26,7 +26,7 @@ #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS #define ARCH_SUPPORTS_FTRACE_OPS 1 #else -#define MCOUNT_ADDR ((unsigned long)function_nocfi(_mcount)) +#define MCOUNT_ADDR ((unsigned long)_mcount) #endif =20 /* The BL at the callsite's adjusted rec->ip */ diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/= mmu_context.h index bba0e630c8bc..d3f8b5df0c1f 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -168,7 +168,7 @@ static inline void cpu_replace_ttbr1(pgd_t *pgdp, pgd_t= *idmap) ttbr1 |=3D TTBR_CNP_BIT; } =20 - replace_phys =3D (void *)__pa_symbol(function_nocfi(idmap_cpu_replace_ttb= r1)); + replace_phys =3D (void *)__pa_symbol(idmap_cpu_replace_ttbr1); =20 __cpu_install_idmap(idmap); replace_phys(ttbr1); diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/= acpi_parking_protocol.c index bfeeb5319abf..b1990e38aed0 100644 --- a/arch/arm64/kernel/acpi_parking_protocol.c +++ b/arch/arm64/kernel/acpi_parking_protocol.c @@ -99,7 +99,7 @@ static int acpi_parking_protocol_cpu_boot(unsigned int cp= u) * that read this address need to convert this address to the * Boot-Loader's endianness before jumping. */ - writeq_relaxed(__pa_symbol(function_nocfi(secondary_entry)), + writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point); writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id); =20 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index ca6e5ca7104e..d8361691efeb 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1713,7 +1713,7 @@ kpti_install_ng_mappings(const struct arm64_cpu_capab= ilities *__unused) if (arm64_use_ng_mappings) return; =20 - remap_fn =3D (void *)__pa_symbol(function_nocfi(idmap_kpti_install_ng_map= pings)); + remap_fn =3D (void *)__pa_symbol(idmap_kpti_install_ng_mappings); =20 if (!cpu) { alloc =3D __get_free_pages(GFP_ATOMIC | __GFP_ZERO, order); diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index ea5dc7c90f46..26789865748c 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -56,7 +56,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func) unsigned long pc; u32 new; =20 - pc =3D (unsigned long)function_nocfi(ftrace_call); + pc =3D (unsigned long)ftrace_call; new =3D aarch64_insn_gen_branch_imm(pc, (unsigned long)func, AARCH64_INSN_BRANCH_LINK); =20 diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_= kexec.c index 19c2d487cb08..ce3d40120f72 100644 --- a/arch/arm64/kernel/machine_kexec.c +++ b/arch/arm64/kernel/machine_kexec.c @@ -204,7 +204,7 @@ void machine_kexec(struct kimage *kimage) typeof(cpu_soft_restart) *restart; =20 cpu_install_idmap(); - restart =3D (void *)__pa_symbol(function_nocfi(cpu_soft_restart)); + restart =3D (void *)__pa_symbol(cpu_soft_restart); restart(is_hyp_nvhe(), kimage->start, kimage->arch.dtb_mem, 0, 0); } else { diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c index ab7f4c476104..29a8e444db83 100644 --- a/arch/arm64/kernel/psci.c +++ b/arch/arm64/kernel/psci.c @@ -38,7 +38,7 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu) =20 static int cpu_psci_cpu_boot(unsigned int cpu) { - phys_addr_t pa_secondary_entry =3D __pa_symbol(function_nocfi(secondary_e= ntry)); + phys_addr_t pa_secondary_entry =3D __pa_symbol(secondary_entry); int err =3D psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry); if (err) pr_err("failed to boot CPU%d (%d)\n", cpu, err); diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spi= n_table.c index 7e1624ecab3c..49029eace3ad 100644 --- a/arch/arm64/kernel/smp_spin_table.c +++ b/arch/arm64/kernel/smp_spin_table.c @@ -66,7 +66,7 @@ static int smp_spin_table_cpu_init(unsigned int cpu) static int smp_spin_table_cpu_prepare(unsigned int cpu) { __le64 __iomem *release_addr; - phys_addr_t pa_holding_pen =3D __pa_symbol(function_nocfi(secondary_holdi= ng_pen)); + phys_addr_t pa_holding_pen =3D __pa_symbol(secondary_holding_pen); =20 if (!cpu_release_addr[cpu]) return -ENODEV; diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c index 75ef784a3789..bc6b5a12bf74 100644 --- a/drivers/firmware/psci/psci.c +++ b/drivers/firmware/psci/psci.c @@ -334,7 +334,7 @@ static int __init psci_features(u32 psci_func_id) static int psci_suspend_finisher(unsigned long state) { u32 power_state =3D state; - phys_addr_t pa_cpu_resume =3D __pa_symbol(function_nocfi(cpu_resume)); + phys_addr_t pa_cpu_resume =3D __pa_symbol(cpu_resume); =20 return psci_ops.cpu_suspend(power_state, pa_cpu_resume); } @@ -359,7 +359,7 @@ int psci_cpu_suspend_enter(u32 state) =20 static int psci_system_suspend(unsigned long unused) { - phys_addr_t pa_cpu_resume =3D __pa_symbol(function_nocfi(cpu_resume)); + phys_addr_t pa_cpu_resume =3D __pa_symbol(cpu_resume); =20 return invoke_psci_fn(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND), pa_cpu_resume, 0, 0); diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c index 6215ec995cd3..67db57249a34 100644 --- a/drivers/misc/lkdtm/usercopy.c +++ b/drivers/misc/lkdtm/usercopy.c @@ -330,7 +330,7 @@ static void lkdtm_USERCOPY_KERNEL(void) =20 pr_info("attempting bad copy_to_user from kernel text: %px\n", vm_mmap); - if (copy_to_user((void __user *)user_addr, function_nocfi(vm_mmap), + if (copy_to_user((void __user *)user_addr, vm_mmap, unconst + PAGE_SIZE)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 7bfafc69172a..973a1bfd7ef5 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -203,16 +203,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f= , int val, __v; \ }) =20 -/* - * With CONFIG_CFI_CLANG, the compiler replaces function addresses in - * instrumented C code with jump table addresses. Architectures that - * support CFI can define this macro to return the actual function address - * when needed. - */ -#ifndef function_nocfi -#define function_nocfi(x) (x) -#endif - #endif /* __KERNEL__ */ =20 /* --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FC17ECAAA1 for ; Tue, 30 Aug 2022 23:35:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232367AbiH3Xdc (ORCPT ); Tue, 30 Aug 2022 19:33:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232268AbiH3Xct (ORCPT ); Tue, 30 Aug 2022 19:32:49 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8DF774DC5 for ; 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charset="utf-8" CONFIG_CFI_CLANG no longer breaks cross-module function address equality, which makes WARN_ON_FUNCTION_MISMATCH unnecessary. Remove the definition and switch back to WARN_ON_ONCE. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- include/asm-generic/bug.h | 16 ---------------- kernel/kthread.c | 3 +-- kernel/workqueue.c | 2 +- 3 files changed, 2 insertions(+), 19 deletions(-) diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index ba1f860af38b..4050b191e1a9 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -220,22 +220,6 @@ extern __printf(1, 2) void __warn_printk(const char *f= mt, ...); # define WARN_ON_SMP(x) ({0;}) #endif =20 -/* - * WARN_ON_FUNCTION_MISMATCH() warns if a value doesn't match a - * function address, and can be useful for catching issues with - * callback functions, for example. - * - * With CONFIG_CFI_CLANG, the warning is disabled because the - * compiler replaces function addresses taken in C code with - * local jump table addresses, which breaks cross-module function - * address equality. - */ -#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_MODULES) -# define WARN_ON_FUNCTION_MISMATCH(x, fn) ({ 0; }) -#else -# define WARN_ON_FUNCTION_MISMATCH(x, fn) WARN_ON_ONCE((x) !=3D (fn)) -#endif - #endif /* __ASSEMBLY__ */ =20 #endif diff --git a/kernel/kthread.c b/kernel/kthread.c index 3c677918d8f2..28a6b7ab4a0f 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1050,8 +1050,7 @@ static void __kthread_queue_delayed_work(struct kthre= ad_worker *worker, struct timer_list *timer =3D &dwork->timer; struct kthread_work *work =3D &dwork->work; =20 - WARN_ON_FUNCTION_MISMATCH(timer->function, - kthread_delayed_work_timer_fn); + WARN_ON_ONCE(timer->function !=3D kthread_delayed_work_timer_fn); =20 /* * If @delay is 0, queue @dwork->work immediately. This is for diff --git a/kernel/workqueue.c b/kernel/workqueue.c index aeea9731ef80..16df315d2a3d 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1651,7 +1651,7 @@ static void __queue_delayed_work(int cpu, struct work= queue_struct *wq, struct work_struct *work =3D &dwork->work; =20 WARN_ON_ONCE(!wq); - WARN_ON_FUNCTION_MISMATCH(timer->function, delayed_work_timer_fn); + WARN_ON_ONCE(timer->function !=3D delayed_work_timer_fn); WARN_ON_ONCE(timer_pending(timer)); WARN_ON_ONCE(!list_empty(&work->entry)); =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0528ECAAD4 for ; Tue, 30 Aug 2022 23:33:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232137AbiH3Xdg (ORCPT ); Tue, 30 Aug 2022 19:33:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231693AbiH3Xcv (ORCPT ); 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charset="utf-8" CONFIG_CFI_CLANG doesn't use a jump table anymore and therefore, won't change function references to point elsewhere. Remove the __cficanonical attribute and all uses of it. Note that the Clang definition of the attribute was removed earlier, just clean up the no-op definition and users. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- include/linux/compiler_types.h | 4 ---- include/linux/init.h | 4 ++-- include/linux/pci.h | 4 ++-- 3 files changed, 4 insertions(+), 8 deletions(-) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 4f2a819fd60a..6f2ec0976e2d 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -265,10 +265,6 @@ struct ftrace_likely_data { # define __nocfi #endif =20 -#ifndef __cficanonical -# define __cficanonical -#endif - /* * Any place that could be marked with the "alloc_size" attribute is also * a place to be marked with the "malloc" attribute. Do this as part of the diff --git a/include/linux/init.h b/include/linux/init.h index 88f2964097f5..a0a90cd73ebe 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -220,8 +220,8 @@ extern bool initcall_debug; __initcall_name(initstub, __iid, id) =20 #define __define_initcall_stub(__stub, fn) \ - int __init __cficanonical __stub(void); \ - int __init __cficanonical __stub(void) \ + int __init __stub(void); \ + int __init __stub(void) \ { \ return fn(); \ } \ diff --git a/include/linux/pci.h b/include/linux/pci.h index 060af91bafcd..5da0846aa3c1 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -2019,8 +2019,8 @@ enum pci_fixup_pass { #ifdef CONFIG_LTO_CLANG #define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ class_shift, hook, stub) \ - void __cficanonical stub(struct pci_dev *dev); \ - void __cficanonical stub(struct pci_dev *dev) \ + void stub(struct pci_dev *dev); \ + void stub(struct pci_dev *dev) \ { \ hook(dev); \ } \ --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64B7AECAAA1 for ; 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charset="utf-8" The __cfi_ preambles contain a mov instruction that embeds the KCFI type identifier in the following format: ; type preamble __cfi_function: mov , %eax function: ... While the preamble symbols are STT_FUNC and contain valid instructions, they are never executed and always fall through. Skip the warning for them. .kcfi_traps sections point to CFI traps in text sections. Also skip the warning about them referencing !ENDBR instructions. Signed-off-by: Sami Tolvanen Acked-by: Josh Poimboeuf Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- tools/objtool/check.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e55fdf952a3a..48e18737a2d1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file= , struct symbol *func, next_insn =3D next_insn_to_validate(file, insn); =20 if (func && insn->func && func !=3D insn->func->pfunc) { + /* Ignore KCFI type preambles, which always fall through */ + if (!strncmp(func->name, "__cfi_", 6)) + return 0; + WARN("%s() falls through to next function %s()", func->name, insn->func->name); return 1; @@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file) !strcmp(sec->name, "__bug_table") || !strcmp(sec->name, "__ex_table") || !strcmp(sec->name, "__jump_table") || - !strcmp(sec->name, "__mcount_loc")) + !strcmp(sec->name, "__mcount_loc") || + !strcmp(sec->name, ".kcfi_traps")) continue; =20 list_for_each_entry(reloc, &sec->reloc->reloc_list, list) --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4634EECAAA1 for ; Tue, 30 Aug 2022 23:33:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232148AbiH3Xdl (ORCPT ); Tue, 30 Aug 2022 19:33:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232340AbiH3XdM (ORCPT ); Tue, 30 Aug 2022 19:33:12 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0AF72923C7 for ; Tue, 30 Aug 2022 16:32:20 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-33dbe61eed8so190027947b3.1 for ; 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charset="utf-8" With -fsanitize=3Dkcfi, the compiler no longer renames static functions with CONFIG_CFI_CLANG + ThinLTO. Drop the code that cleans up the ThinLTO hash from the function names. Signed-off-by: Sami Tolvanen Reviewed-by: Nick Desaulniers Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- kernel/kallsyms.c | 17 ----------------- 1 file changed, 17 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 3e7e2c2ad2f7..b27e6ea31f8b 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -159,7 +159,6 @@ static bool cleanup_symbol_name(char *s) * character in an identifier in C. Suffixes observed: * - foo.llvm.[0-9a-f]+ * - foo.[0-9a-f]+ - * - foo.[0-9a-f]+.cfi_jt */ res =3D strchr(s, '.'); if (res) { @@ -167,22 +166,6 @@ static bool cleanup_symbol_name(char *s) return true; } =20 - if (!IS_ENABLED(CONFIG_CFI_CLANG) || - !IS_ENABLED(CONFIG_LTO_CLANG_THIN) || - CONFIG_CLANG_VERSION >=3D 130000) - return false; - - /* - * Prior to LLVM 13, the following suffixes were observed when thinLTO - * and CFI are both enabled: - * - foo$[0-9]+ - */ - res =3D strrchr(s, '$'); - if (res) { - *res =3D '\0'; - return true; - } - return false; } =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72739ECAAD4 for ; Tue, 30 Aug 2022 23:33:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231184AbiH3Xdo (ORCPT ); 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Tue, 30 Aug 2022 16:32:22 -0700 (PDT) Date: Tue, 30 Aug 2022 16:31:26 -0700 In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> Message-Id: <20220830233129.30610-19-samitolvanen@google.com> Mime-Version: 1.0 References: <20220830233129.30610-1-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=804; i=samitolvanen@google.com; h=from:subject; bh=PQGbduDYSHEunY6Nux9oR4b8gX3kqUUQ66z3bs0DO/k=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBjDp3OHJOh3MpkrcMboNL3mLB+U7xNHC0btjo7mME4 CgYIObyJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYw6dzgAKCRBMtfaEi7xW7ibxC/ 9u8tiBUAu11iMi2jQxB88ZoyRd3XcPtlmEJ49ZT4ibCRTKCQwU7x7cDMnDG2jMK91BvisB+yihmg9w N/xNoX9Du1hqgmpQ189vSRzZ8B3cTextiO0ei30mC5sYpY4O7ZzhfZ2RUhJ9GhDyhAqAEf/dyh6i7R slJI0p2V7MK2rO8Z0jyvl0g73TadyQ3IuIyhqfnc0JWw795W5qT0rTDncrsYsDg9bHqVA69umBLW/E JBpKqxPr5+1G3RypfC6VZNWayPrVcMVECCxIeWoI8JfgWyBD5zQ2Zeyjo3El1kUNH/J3pinc2ucgj0 nCmZucarH0zhjvQSUJC5X8OSCGQyDJClv+hqBEIWhQ0gvLN9UVnXd5Ql7r49YFrN1kk9AWrqjbQ3Sc AD5ZEd5SjOGYRv3rAgmv+XiFslu7d+xB6EyKfNX1+EmfFdYMhyVFQNijCiaFZSRvXJJ7dnhc8wF96j FE3UOfpxc1eA3nQd4sJS9gasOaTmoIocuonggQXaz5kqM= X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Subject: [PATCH v4 18/21] x86/tools/relocs: Ignore __kcfi_typeid_ relocations From: Sami Tolvanen To: linux-kernel@vger.kernel.org Cc: Kees Cook , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The compiler generates __kcfi_typeid_ symbols for annotating assembly functions with type information. These are constants that can be referenced in assembly code and are resolved by the linker. Ignore them in relocs. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/x86/tools/relocs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index e2c5b296120d..2925074b9a58 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -56,6 +56,7 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = =3D { "^(xen_irq_disable_direct_reloc$|" "xen_save_fl_direct_reloc$|" "VDSO|" + "__kcfi_typeid_|" "__crc_)", =20 /* --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A719BECAAD4 for ; Tue, 30 Aug 2022 23:33:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232394AbiH3Xd5 (ORCPT ); Tue, 30 Aug 2022 19:33:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232262AbiH3Xd2 (ORCPT ); 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charset="utf-8" With CONFIG_CFI_CLANG, assembly functions indirectly called from C code must be annotated with type identifiers to pass CFI checking. Add types to indirectly called functions. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/x86/crypto/blowfish-x86_64-asm_64.S | 5 +++-- arch/x86/lib/memcpy_64.S | 3 ++- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/crypto/blowfish-x86_64-asm_64.S b/arch/x86/crypto/blo= wfish-x86_64-asm_64.S index 802d71582689..4a43e072d2d1 100644 --- a/arch/x86/crypto/blowfish-x86_64-asm_64.S +++ b/arch/x86/crypto/blowfish-x86_64-asm_64.S @@ -6,6 +6,7 @@ */ =20 #include +#include =20 .file "blowfish-x86_64-asm.S" .text @@ -141,7 +142,7 @@ SYM_FUNC_START(__blowfish_enc_blk) RET; SYM_FUNC_END(__blowfish_enc_blk) =20 -SYM_FUNC_START(blowfish_dec_blk) +SYM_TYPED_FUNC_START(blowfish_dec_blk) /* input: * %rdi: ctx * %rsi: dst @@ -332,7 +333,7 @@ SYM_FUNC_START(__blowfish_enc_blk_4way) RET; SYM_FUNC_END(__blowfish_enc_blk_4way) =20 -SYM_FUNC_START(blowfish_dec_blk_4way) +SYM_TYPED_FUNC_START(blowfish_dec_blk_4way) /* input: * %rdi: ctx * %rsi: dst diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index d0d7b9bc6cad..e5d9b299577f 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -2,6 +2,7 @@ /* Copyright 2002 Andi Kleen */ =20 #include +#include #include #include #include @@ -27,7 +28,7 @@ * Output: * rax original destination */ -SYM_FUNC_START(__memcpy) +__SYM_TYPED_FUNC_START(__memcpy, memcpy) ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ "jmp memcpy_erms", X86_FEATURE_ERMS =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1A35ECAAD4 for ; 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charset="utf-8" Disable CONFIG_CFI_CLANG for the stand-alone purgatory.ro. Signed-off-by: Sami Tolvanen Reviewed-by: Nick Desaulniers Reviewed-by: Kees Cook Tested-by: Nick Desaulniers Tested-by: Sedat Dilek Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/x86/purgatory/Makefile | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index 31c634a22818..58a200dc762d 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile @@ -55,6 +55,10 @@ ifdef CONFIG_RETPOLINE PURGATORY_CFLAGS_REMOVE +=3D $(RETPOLINE_CFLAGS) endif =20 +ifdef CONFIG_CFI_CLANG +PURGATORY_CFLAGS_REMOVE +=3D $(CC_FLAGS_CFI) +endif + CFLAGS_REMOVE_purgatory.o +=3D $(PURGATORY_CFLAGS_REMOVE) CFLAGS_purgatory.o +=3D $(PURGATORY_CFLAGS) =20 --=20 2.37.2.672.g94769d06f0-goog From nobody Tue Apr 7 05:56:11 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58C39ECAAD4 for ; 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charset="utf-8" With CONFIG_CFI_CLANG, the compiler injects a type preamble immediately before each function and a check to validate the target function type before indirect calls: ; type preamble __cfi_function: mov , %eax function: ... ; indirect call check mov -,%r10d add -0x4(%r11),%r10d je .Ltmp1 ud2 .Ltmp1: call __x86_indirect_thunk_r11 Define the __CFI_TYPE helper macro for manually annotating indirectly called assembly function with the identical premable, add error handling code for the ud2 traps emitted for indirect call checks, and allow CONFIG_CFI_CLANG to be selected on x86_64. This produces the following oops on CFI failure (generated using lkdtm): [ 21.441706] CFI failure at lkdtm_indirect_call+0x16/0x20 [lkdtm] (target: lkdtm_increment_int+0x0/0x10 [lkdtm]; expected type: 0x7e0c52a) [ 21.444579] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 21.445296] CPU: 0 PID: 132 Comm: sh Not tainted 5.19.0-rc8-00020-g9f27360e674c #1 [ 21.445296] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 21.445296] RIP: 0010:lkdtm_indirect_call+0x16/0x20 [lkdtm] [ 21.445296] Code: 52 1c c0 48 c7 c1 c5 50 1c c0 e9 25 48 2a cc 0f 1f 44 00 00 49 89 fb 48 c7 c7 50 b4 1c c0 41 ba 5b ad f3 81 45 03 53 f8 [ 21.445296] RSP: 0018:ffffa9f9c02ffdc0 EFLAGS: 00000292 [ 21.445296] RAX: 0000000000000027 RBX: ffffffffc01cb300 RCX: 385cbbd2e07= 0a700 [ 21.445296] RDX: 0000000000000000 RSI: c0000000ffffdfff RDI: ffffffffc01= cb450 [ 21.445296] RBP: 0000000000000006 R08: 0000000000000000 R09: ffffffff8d0= 81610 [ 21.445296] R10: 00000000bcc90825 R11: ffffffffc01c2fc0 R12: 00000000000= 00000 [ 21.445296] R13: ffffa31b827a6000 R14: 0000000000000000 R15: 00000000000= 00002 [ 21.445296] FS: 00007f08b42216a0(0000) GS:ffffa31b9f400000(0000) knlGS:0000000000000000 [ 21.445296] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.445296] CR2: 0000000000c76678 CR3: 0000000001940000 CR4: 00000000000= 006f0 [ 21.445296] Call Trace: [ 21.445296] [ 21.445296] lkdtm_CFI_FORWARD_PROTO+0x30/0x50 [lkdtm] [ 21.445296] direct_entry+0x12d/0x140 [lkdtm] [ 21.445296] full_proxy_write+0x5d/0xb0 [ 21.445296] vfs_write+0x144/0x460 [ 21.445296] ? __x64_sys_wait4+0x5a/0xc0 [ 21.445296] ksys_write+0x69/0xd0 [ 21.445296] do_syscall_64+0x51/0xa0 [ 21.445296] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 21.445296] RIP: 0033:0x7f08b41a6fe1 [ 21.445296] Code: be 07 00 00 00 41 89 c0 e8 7e ff ff ff 44 89 c7 89 04 24 e8 91 c6 02 00 8b 04 24 48 83 c4 68 c3 48 63 ff b8 01 00 00 03 [ 21.445296] RSP: 002b:00007ffcdf65c2e8 EFLAGS: 00000246 ORIG_RAX: 000000= 0000000001 [ 21.445296] RAX: ffffffffffffffda RBX: 00007f08b4221690 RCX: 00007f08b41= a6fe1 [ 21.445296] RDX: 0000000000000012 RSI: 0000000000c738f0 RDI: 00000000000= 00001 [ 21.445296] RBP: 0000000000000001 R08: fefefefefefefeff R09: fefefefeffc= 5ff4e [ 21.445296] R10: 00007f08b42222b0 R11: 0000000000000246 R12: 0000000000c= 738f0 [ 21.445296] R13: 0000000000000012 R14: 00007ffcdf65c401 R15: 0000000000c= 70450 [ 21.445296] [ 21.445296] Modules linked in: lkdtm [ 21.445296] Dumping ftrace buffer: [ 21.445296] (ftrace buffer empty) [ 21.471442] ---[ end trace 0000000000000000 ]--- [ 21.471811] RIP: 0010:lkdtm_indirect_call+0x16/0x20 [lkdtm] [ 21.472467] Code: 52 1c c0 48 c7 c1 c5 50 1c c0 e9 25 48 2a cc 0f 1f 44 00 00 49 89 fb 48 c7 c7 50 b4 1c c0 41 ba 5b ad f3 81 45 03 53 f8 [ 21.474400] RSP: 0018:ffffa9f9c02ffdc0 EFLAGS: 00000292 [ 21.474735] RAX: 0000000000000027 RBX: ffffffffc01cb300 RCX: 385cbbd2e07= 0a700 [ 21.475664] RDX: 0000000000000000 RSI: c0000000ffffdfff RDI: ffffffffc01= cb450 [ 21.476471] RBP: 0000000000000006 R08: 0000000000000000 R09: ffffffff8d0= 81610 [ 21.477127] R10: 00000000bcc90825 R11: ffffffffc01c2fc0 R12: 00000000000= 00000 [ 21.477959] R13: ffffa31b827a6000 R14: 0000000000000000 R15: 00000000000= 00002 [ 21.478657] FS: 00007f08b42216a0(0000) GS:ffffa31b9f400000(0000) knlGS:0000000000000000 [ 21.479577] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.480307] CR2: 0000000000c76678 CR3: 0000000001940000 CR4: 00000000000= 006f0 [ 21.481460] Kernel panic - not syncing: Fatal exception Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor --- arch/x86/Kconfig | 2 + arch/x86/include/asm/cfi.h | 22 +++++++++ arch/x86/include/asm/linkage.h | 9 ++++ arch/x86/kernel/Makefile | 2 + arch/x86/kernel/cfi.c | 85 ++++++++++++++++++++++++++++++++++ arch/x86/kernel/traps.c | 4 +- 6 files changed, 123 insertions(+), 1 deletion(-) create mode 100644 arch/x86/include/asm/cfi.h create mode 100644 arch/x86/kernel/cfi.c diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f9920f1341c8..1fe6a83dac05 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -107,6 +107,8 @@ config X86 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <=3D 4096 + select ARCH_SUPPORTS_CFI_CLANG if X86_64 + select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG select ARCH_SUPPORTS_LTO_CLANG select ARCH_SUPPORTS_LTO_CLANG_THIN select ARCH_USE_BUILTIN_BSWAP diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h new file mode 100644 index 000000000000..58dacd90daef --- /dev/null +++ b/arch/x86/include/asm/cfi.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_CFI_H +#define _ASM_X86_CFI_H + +/* + * Clang Control Flow Integrity (CFI) support. + * + * Copyright (C) 2022 Google LLC + */ + +#include + +#ifdef CONFIG_CFI_CLANG +enum bug_trap_type handle_cfi_failure(struct pt_regs *regs); +#else +static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) +{ + return BUG_TRAP_TYPE_NONE; +} +#endif /* CONFIG_CFI_CLANG */ + +#endif /* _ASM_X86_CFI_H */ diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h index 73ca20049835..ebfa05973312 100644 --- a/arch/x86/include/asm/linkage.h +++ b/arch/x86/include/asm/linkage.h @@ -29,6 +29,15 @@ #endif #endif /* CONFIG_RETPOLINE */ =20 +#ifdef CONFIG_CFI_CLANG +#define __CFI_TYPE(name) \ + SYM_START(__cfi_##name, SYM_L_LOCAL, SYM_A_NONE) \ + .fill 11, 1, 0x90 ASM_NL \ + .byte 0xb8 ASM_NL \ + .long __kcfi_typeid_##name ASM_NL \ + SYM_FUNC_END(__cfi_##name) +#endif + #else /* __ASSEMBLY__ */ =20 #if defined(CONFIG_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUI= LD_VDSO) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index a20a5ebfacd7..1286a73ebdbc 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -139,6 +139,8 @@ obj-$(CONFIG_UNWINDER_GUESS) +=3D unwind_guess.o =20 obj-$(CONFIG_AMD_MEM_ENCRYPT) +=3D sev.o =20 +obj-$(CONFIG_CFI_CLANG) +=3D cfi.o + ### # 64 bit specific files ifeq ($(CONFIG_X86_64),y) diff --git a/arch/x86/kernel/cfi.c b/arch/x86/kernel/cfi.c new file mode 100644 index 000000000000..e642c1af2678 --- /dev/null +++ b/arch/x86/kernel/cfi.c @@ -0,0 +1,85 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Clang Control Flow Integrity (CFI) support. + * + * Copyright (C) 2022 Google LLC + */ +#include +#include +#include + +/* + * Returns the target address and the expected type when regs->ip points + * to a compiler-generated CFI trap. + */ +static bool decode_cfi_insn(struct pt_regs *regs, unsigned long *target, + u32 *type) +{ + char buffer[MAX_INSN_SIZE]; + struct insn insn; + int offset =3D 0; + + *target =3D *type =3D 0; + + /* + * The compiler generates the following instruction sequence + * for indirect call checks: + * + * =C2=A0 movl -, %r10d ; 6 bytes + * addl -4(%reg), %r10d ; 4 bytes + * je .Ltmp1 ; 2 bytes + * ud2 ; <- regs->ip + * .Ltmp1: + * + * We can decode the expected type and the target address from the + * movl/addl instructions. + */ + if (copy_from_kernel_nofault(buffer, (void *)regs->ip - 12, MAX_INSN_SIZE= )) + return false; + if (insn_decode_kernel(&insn, &buffer[offset])) + return false; + if (insn.opcode.value !=3D 0xBA) + return false; + + *type =3D -(u32)insn.immediate.value; + + if (copy_from_kernel_nofault(buffer, (void *)regs->ip - 6, MAX_INSN_SIZE)) + return false; + if (insn_decode_kernel(&insn, &buffer[offset])) + return false; + if (insn.opcode.value !=3D 0x3) + return false; + + /* Read the target address from the register. */ + offset =3D insn_get_modrm_rm_off(&insn, regs); + if (offset < 0) + return false; + + *target =3D *(unsigned long *)((void *)regs + offset); + + return true; +} + +/* + * Checks if a ud2 trap is because of a CFI failure, and handles the trap + * if needed. Returns a bug_trap_type value similarly to report_bug. + */ +enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) +{ + unsigned long target; + u32 type; + + if (!is_cfi_trap(regs->ip)) + return BUG_TRAP_TYPE_NONE; + + if (!decode_cfi_insn(regs, &target, &type)) + return report_cfi_failure_noaddr(regs, regs->ip); + + return report_cfi_failure(regs, regs->ip, &target, type); +} + +/* + * Ensure that __kcfi_typeid_ symbols are emitted for functions that may + * not be indirectly called with all configurations. + */ +__ADDRESSABLE(memcpy) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index d62b2cb85cea..178015a820f0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -63,6 +63,7 @@ #include #include #include +#include =20 #ifdef CONFIG_X86_64 #include @@ -313,7 +314,8 @@ static noinstr bool handle_bug(struct pt_regs *regs) */ if (regs->flags & X86_EFLAGS_IF) raw_local_irq_enable(); - if (report_bug(regs->ip, regs) =3D=3D BUG_TRAP_TYPE_WARN) { + if (report_bug(regs->ip, regs) =3D=3D BUG_TRAP_TYPE_WARN || + handle_cfi_failure(regs) =3D=3D BUG_TRAP_TYPE_WARN) { regs->ip +=3D LEN_UD2; handled =3D true; } --=20 2.37.2.672.g94769d06f0-goog