From patchwork Mon Mar 12 03:03:34 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Hutchings X-Patchwork-Id: 10276171 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E980D602BD for ; Mon, 12 Mar 2018 12:48:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D69E0286B8 for ; Mon, 12 Mar 2018 12:48:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CB07D287F5; Mon, 12 Mar 2018 12:48:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 50748287E6 for ; Mon, 12 Mar 2018 12:48:10 +0000 (UTC) Received: (qmail 5541 invoked by uid 550); 12 Mar 2018 12:45:18 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 30465 invoked from network); 12 Mar 2018 03:08:10 -0000 Content-Disposition: inline MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, linux-arch@vger.kernel.org, "Al Viro" , gregkh@linuxfoundation.org, "Thomas Gleixner" , "Andi Kleen" , "Dan Williams" , kernel-hardening@lists.openwall.com, "Linus Torvalds" , "Kees Cook" , alan@linux.intel.com Date: Mon, 12 Mar 2018 03:03:34 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 102/104] x86/uaccess: Use __uaccess_begin_nospec() and uaccess_try_nospec In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false X-Virus-Scanned: ClamAV using ClamSMTP 3.2.101-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit 304ec1b050310548db33063e567123fae8fd0301 upstream. Quoting Linus: I do think that it would be a good idea to very expressly document the fact that it's not that the user access itself is unsafe. I do agree that things like "get_user()" want to be protected, but not because of any direct bugs or problems with get_user() and friends, but simply because get_user() is an excellent source of a pointer that is obviously controlled from a potentially attacking user space. So it's a prime candidate for then finding _subsequent_ accesses that can then be used to perturb the cache. __uaccess_begin_nospec() covers __get_user() and copy_from_iter() where the limit check is far away from the user pointer de-reference. In those cases a barrier_nospec() prevents speculation with a potential pointer to privileged memory. uaccess_try_nospec covers get_user_try. Suggested-by: Linus Torvalds Suggested-by: Andi Kleen Signed-off-by: Dan Williams Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: Kees Cook Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727416953.33451.10508284228526170604.stgit@dwillia2-desk3.amr.corp.intel.com [bwh: Backported to 3.2: - There's no SMAP support, so use barrier_nospec() directly instead of __uaccess_begin_nospec() - Convert several more functions to use barrier_nospec(), that are just wrappers in mainline - There's no 'case 8' in __copy_to_user_inatomic() - Adjust context] Signed-off-by: Ben Hutchings --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -423,6 +423,7 @@ do { \ ({ \ int __gu_err; \ unsigned long __gu_val; \ + barrier_nospec(); \ __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ __gu_err; \ @@ -529,7 +530,7 @@ struct __large_struct { unsigned long bu * get_user_ex(...); * } get_user_catch(err) */ -#define get_user_try uaccess_try +#define get_user_try uaccess_try_nospec #define get_user_catch(err) uaccess_catch(err) #define get_user_ex(x, ptr) do { \ --- a/arch/x86/include/asm/uaccess_32.h +++ b/arch/x86/include/asm/uaccess_32.h @@ -48,14 +48,17 @@ __copy_to_user_inatomic(void __user *to, switch (n) { case 1: + barrier_nospec(); __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1); return ret; case 2: + barrier_nospec(); __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2); return ret; case 4: + barrier_nospec(); __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4); return ret; @@ -98,12 +101,15 @@ __copy_from_user_inatomic(void *to, cons switch (n) { case 1: + barrier_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); return ret; case 2: + barrier_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); return ret; case 4: + barrier_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); return ret; } @@ -142,12 +148,15 @@ __copy_from_user(void *to, const void __ switch (n) { case 1: + barrier_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); return ret; case 2: + barrier_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); return ret; case 4: + barrier_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); return ret; } @@ -164,12 +173,15 @@ static __always_inline unsigned long __c switch (n) { case 1: + barrier_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); return ret; case 2: + barrier_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); return ret; case 4: + barrier_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); return ret; } --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -75,19 +75,28 @@ int __copy_from_user_nocheck(void *dst, if (!__builtin_constant_p(size)) return copy_user_generic(dst, (__force void *)src, size); switch (size) { - case 1:__get_user_asm(*(u8 *)dst, (u8 __user *)src, + case 1: + barrier_nospec(); + __get_user_asm(*(u8 *)dst, (u8 __user *)src, ret, "b", "b", "=q", 1); return ret; - case 2:__get_user_asm(*(u16 *)dst, (u16 __user *)src, + case 2: + barrier_nospec(); + __get_user_asm(*(u16 *)dst, (u16 __user *)src, ret, "w", "w", "=r", 2); return ret; - case 4:__get_user_asm(*(u32 *)dst, (u32 __user *)src, + case 4: + barrier_nospec(); + __get_user_asm(*(u32 *)dst, (u32 __user *)src, ret, "l", "k", "=r", 4); return ret; - case 8:__get_user_asm(*(u64 *)dst, (u64 __user *)src, + case 8: + barrier_nospec(); + __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 8); return ret; case 10: + barrier_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 10); if (unlikely(ret)) @@ -97,6 +106,7 @@ int __copy_from_user_nocheck(void *dst, ret, "w", "w", "=r", 2); return ret; case 16: + barrier_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 16); if (unlikely(ret)) @@ -179,6 +189,7 @@ int __copy_in_user(void __user *dst, con switch (size) { case 1: { u8 tmp; + barrier_nospec(); __get_user_asm(tmp, (u8 __user *)src, ret, "b", "b", "=q", 1); if (likely(!ret)) @@ -188,6 +199,7 @@ int __copy_in_user(void __user *dst, con } case 2: { u16 tmp; + barrier_nospec(); __get_user_asm(tmp, (u16 __user *)src, ret, "w", "w", "=r", 2); if (likely(!ret)) @@ -198,6 +210,7 @@ int __copy_in_user(void __user *dst, con case 4: { u32 tmp; + barrier_nospec(); __get_user_asm(tmp, (u32 __user *)src, ret, "l", "k", "=r", 4); if (likely(!ret)) @@ -207,6 +220,7 @@ int __copy_in_user(void __user *dst, con } case 8: { u64 tmp; + barrier_nospec(); __get_user_asm(tmp, (u64 __user *)src, ret, "q", "", "=r", 8); if (likely(!ret)) --- a/arch/x86/lib/usercopy_32.c +++ b/arch/x86/lib/usercopy_32.c @@ -774,6 +774,7 @@ survive: return n; } #endif + barrier_nospec(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else @@ -785,6 +786,7 @@ EXPORT_SYMBOL(__copy_to_user_ll); unsigned long __copy_from_user_ll(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); if (movsl_is_ok(to, from, n)) __copy_user_zeroing(to, from, n); else @@ -796,6 +798,7 @@ EXPORT_SYMBOL(__copy_from_user_ll); unsigned long __copy_from_user_ll_nozero(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else @@ -808,6 +811,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nozero unsigned long __copy_from_user_ll_nocache(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_zeroing_intel_nocache(to, from, n); @@ -823,6 +827,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nocach unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from, unsigned long n) { + barrier_nospec(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_intel_nocache(to, from, n);