From mboxrd@z Thu Jan 1 00:00:00 1970 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 E5D4AC433EF for ; Tue, 8 Feb 2022 23:25:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236569AbiBHXZ3 (ORCPT ); Tue, 8 Feb 2022 18:25:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234907AbiBHXZ2 (ORCPT ); Tue, 8 Feb 2022 18:25:28 -0500 Received: from mail-lf1-x130.google.com (mail-lf1-x130.google.com [IPv6:2a00:1450:4864:20::130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F65AC061577 for ; Tue, 8 Feb 2022 15:25:27 -0800 (PST) Received: by mail-lf1-x130.google.com with SMTP id o2so956054lfd.1 for ; Tue, 08 Feb 2022 15:25:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4ybyNtcdRyROTIcJwyZJbn1sv4gx5S92IIuJFLeS5wE=; b=KG6vrM5bdpvRtl2iMpgfqF0TpAP4hhLSinh9EXzm6Vyf38iVoLzQrKhnzTRqF3XO9G cp5jwaF7ak9/xU7IpdTRW/59RP8pKASg3qEYfsj9zmHFGqo+vHKTDh9C6m4ZjIAlqP23 zuu89wXVmrnGvA/3I+Qi6BRvnFZZjQGFOOP03vpDfiMoi+401+pmVIsqT/iD9AuSUwFu a6IqJCExA3yqow1OPzgph62zpgMrHDftSyuRc6h5N3/bySsRGfxHz6m2oEKjAhaBPwFb 61GK89d+z2hBg+6ETQRLMWZ2WWMP4cNPiFLDUuQ70w0nrY4xTVctPgyT8v3MqU4dINQW ucsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=4ybyNtcdRyROTIcJwyZJbn1sv4gx5S92IIuJFLeS5wE=; b=ojcVUerq/QKzdwVtuFJYfeNGSO240woFNF3/ksNnur3fHPVoOfwH9FfqHr3/f01Eiw UeIDNIetcmFJwycfb21HZDuOKCac6VWhCGYA/CSsgv0bRBvN9uV3DsQZYbqLk7DibvXO f7ZU3JN0YLV2/bSmJBVQYAk/3JQKrzo+TJiuQN8KHjiP0osNkWwMiOanDrSJpD2chLqx bApLN4PrSkgurPo1l7ZgwFo/vZnyLRdKBeozf4TRd35pdALTgBd7G0TejJIy997EfKj9 EnSgkFD0WT8Q1/Q1ePoOtmaK0DI17uZ2z4ZBBo+D8RhsIioYgwfjQx8GcBvlnTfs9jjx j9yg== X-Gm-Message-State: AOAM533xkBBjv3objouR2uHxbhAP8+h6HwXSgyS01CJHeDjhAAUryEZ+ JbbaEW7faWHKZCvChNBqzKRydef5brBp4tTBsMpOsg== X-Google-Smtp-Source: ABdhPJwU6ArHQMfifMwI39CPeSZp3Yy2hdcF+jpnVLhoccKbOgmiYHA7ijFnR8dr6EEK8l9qcZ3AN8Kg54/OyBoeBeU= X-Received: by 2002:a05:6512:3f97:: with SMTP id x23mr2091419lfa.550.1644362725282; Tue, 08 Feb 2022 15:25:25 -0800 (PST) MIME-Version: 1.0 References: <20220208225350.1331628-1-keescook@chromium.org> <20220208225350.1331628-9-keescook@chromium.org> In-Reply-To: <20220208225350.1331628-9-keescook@chromium.org> From: Nick Desaulniers Date: Tue, 8 Feb 2022 15:25:13 -0800 Message-ID: Subject: Re: [PATCH v7 8/8] fortify: Add Clang support To: Kees Cook Cc: Miguel Ojeda , Nathan Chancellor , George Burgess IV , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 8, 2022 at 2:53 PM Kees Cook wrote: > > Enable FORTIFY_SOURCE support for Clang: > > Use the new __pass_object_size and __overloadable attributes so that > Clang will have appropriate visibility into argument sizes such that > __builtin_object_size(p, 1) will behave correctly. Additional details > available here: > https://github.com/llvm/llvm-project/issues/53516 > https://github.com/ClangBuiltLinux/linux/issues/1401 > > A bug with __builtin_constant_p() of globally defined variables was > fixed in Clang 13 (and backported to 12.0.1), so FORTIFY support must > depend on that version or later. Additional details here: > https://bugs.llvm.org/show_bug.cgi?id=41459 > commit a52f8a59aef4 ("fortify: Explicitly disable Clang support") > > A bug with Clang's -mregparm=3 and -m32 makes some builtins unusable, > so removing -ffreestanding (to gain the needed libcall optimizations > with Clang) cannot be done. Without the libcall optimizations, Clang > cannot provide appropriate FORTIFY coverage, so it must be disabled > for CONFIG_X86_32. Additional details here; > https://github.com/llvm/llvm-project/issues/53645 Nice job on this series Kees! Hopefully we can get i386 support working next! Reviewed-by: Nick Desaulniers > > Cc: Miguel Ojeda > Cc: Nick Desaulniers > Cc: Nathan Chancellor > Cc: George Burgess IV > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook > --- > include/linux/fortify-string.h | 40 ++++++++++++++++++++++------------ > security/Kconfig | 5 +++-- > 2 files changed, 29 insertions(+), 16 deletions(-) > > diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h > index f77cf22e2d60..295637a66c46 100644 > --- a/include/linux/fortify-string.h > +++ b/include/linux/fortify-string.h > @@ -4,7 +4,7 @@ > > #include > > -#define __FORTIFY_INLINE extern __always_inline __gnu_inline > +#define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable > #define __RENAME(x) __asm__(#x) > > void fortify_panic(const char *name) __noreturn __cold; > @@ -52,8 +52,17 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) > #define __underlying_strncpy __builtin_strncpy > #endif > > +/* > + * Clang's use of __builtin_object_size() within inlines needs hinting via > + * __pass_object_size(). The preference is to only ever use type 1 (member > + * size, rather than struct size), but there remain some stragglers using > + * type 0 that will be converted in the future. > + */ > +#define POS __pass_object_size(1) > +#define POS0 __pass_object_size(0) > + > __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3) > -char *strncpy(char * const p, const char *q, __kernel_size_t size) > +char *strncpy(char * const POS p, const char *q, __kernel_size_t size) > { > size_t p_size = __builtin_object_size(p, 1); > > @@ -65,7 +74,7 @@ char *strncpy(char * const p, const char *q, __kernel_size_t size) > } > > __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2) > -char *strcat(char * const p, const char *q) > +char *strcat(char * const POS p, const char *q) > { > size_t p_size = __builtin_object_size(p, 1); > > @@ -77,7 +86,7 @@ char *strcat(char * const p, const char *q) > } > > extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen); > -__FORTIFY_INLINE __kernel_size_t strnlen(const char * const p, __kernel_size_t maxlen) > +__FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen) > { > size_t p_size = __builtin_object_size(p, 1); > size_t p_len = __compiletime_strlen(p); > @@ -106,7 +115,7 @@ __FORTIFY_INLINE __kernel_size_t strnlen(const char * const p, __kernel_size_t m > __builtin_choose_expr(__is_constexpr(__builtin_strlen(p)), \ > __builtin_strlen(p), __fortify_strlen(p)) > __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1) > -__kernel_size_t __fortify_strlen(const char * const p) > +__kernel_size_t __fortify_strlen(const char * const POS p) > { > __kernel_size_t ret; > size_t p_size = __builtin_object_size(p, 1); > @@ -122,7 +131,7 @@ __kernel_size_t __fortify_strlen(const char * const p) > > /* defined after fortified strlen to reuse it */ > extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy); > -__FORTIFY_INLINE size_t strlcpy(char * const p, const char * const q, size_t size) > +__FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size) > { > size_t p_size = __builtin_object_size(p, 1); > size_t q_size = __builtin_object_size(q, 1); > @@ -149,7 +158,7 @@ __FORTIFY_INLINE size_t strlcpy(char * const p, const char * const q, size_t siz > > /* defined after fortified strnlen to reuse it */ > extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy); > -__FORTIFY_INLINE ssize_t strscpy(char * const p, const char * const q, size_t size) > +__FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, size_t size) > { > size_t len; > /* Use string size rather than possible enclosing struct size. */ > @@ -196,7 +205,7 @@ __FORTIFY_INLINE ssize_t strscpy(char * const p, const char * const q, size_t si > > /* defined after fortified strlen and strnlen to reuse them */ > __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3) > -char *strncat(char * const p, const char * const q, __kernel_size_t count) > +char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count) > { > size_t p_len, copy_len; > size_t p_size = __builtin_object_size(p, 1); > @@ -367,7 +376,7 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, > memmove) > > extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); > -__FORTIFY_INLINE void *memscan(void * const p, int c, __kernel_size_t size) > +__FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size) > { > size_t p_size = __builtin_object_size(p, 0); > > @@ -379,7 +388,7 @@ __FORTIFY_INLINE void *memscan(void * const p, int c, __kernel_size_t size) > } > > __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3) > -int memcmp(const void * const p, const void * const q, __kernel_size_t size) > +int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size) > { > size_t p_size = __builtin_object_size(p, 0); > size_t q_size = __builtin_object_size(q, 0); > @@ -396,7 +405,7 @@ int memcmp(const void * const p, const void * const q, __kernel_size_t size) > } > > __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3) > -void *memchr(const void * const p, int c, __kernel_size_t size) > +void *memchr(const void * const POS0 p, int c, __kernel_size_t size) > { > size_t p_size = __builtin_object_size(p, 0); > > @@ -408,7 +417,7 @@ void *memchr(const void * const p, int c, __kernel_size_t size) > } > > void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv); > -__FORTIFY_INLINE void *memchr_inv(const void * const p, int c, size_t size) > +__FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) > { > size_t p_size = __builtin_object_size(p, 0); > > @@ -420,7 +429,7 @@ __FORTIFY_INLINE void *memchr_inv(const void * const p, int c, size_t size) > } > > extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup); > -__FORTIFY_INLINE void *kmemdup(const void * const p, size_t size, gfp_t gfp) > +__FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp) > { > size_t p_size = __builtin_object_size(p, 0); > > @@ -433,7 +442,7 @@ __FORTIFY_INLINE void *kmemdup(const void * const p, size_t size, gfp_t gfp) > > /* Defined after fortified strlen to reuse it. */ > __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2) > -char *strcpy(char * const p, const char * const q) > +char *strcpy(char * const POS p, const char * const POS q) > { > size_t p_size = __builtin_object_size(p, 1); > size_t q_size = __builtin_object_size(q, 1); > @@ -462,4 +471,7 @@ char *strcpy(char * const p, const char * const q) > #undef __underlying_strncat > #undef __underlying_strncpy > > +#undef POS > +#undef POS0 > + > #endif /* _LINUX_FORTIFY_STRING_H_ */ > diff --git a/security/Kconfig b/security/Kconfig > index 0b847f435beb..1d2d71cc1f36 100644 > --- a/security/Kconfig > +++ b/security/Kconfig > @@ -177,9 +177,10 @@ config HARDENED_USERCOPY_PAGESPAN > config FORTIFY_SOURCE > bool "Harden common str/mem functions against buffer overflows" > depends on ARCH_HAS_FORTIFY_SOURCE > - # https://bugs.llvm.org/show_bug.cgi?id=50322 > # https://bugs.llvm.org/show_bug.cgi?id=41459 > - depends on !CC_IS_CLANG > + depends on !CC_IS_CLANG || CLANG_VERSION >= 120001 > + # https://github.com/llvm/llvm-project/issues/53645 > + depends on !CC_IS_CLANG || !X86_32 > help > Detect overflows of buffers in common string and memory functions > where the compiler can determine and validate the buffer sizes. > -- > 2.30.2 > > -- Thanks, ~Nick Desaulniers