From patchwork Mon Mar 12 03:06:12 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Hutchings X-Patchwork-Id: 10276159 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 E1D67601A0 for ; Mon, 12 Mar 2018 12:46:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C9B2528BF5 for ; Mon, 12 Mar 2018 12:46:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BE52728DA7; Mon, 12 Mar 2018 12:46:49 +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 5038828BF5 for ; Mon, 12 Mar 2018 12:46:48 +0000 (UTC) Received: (qmail 3179 invoked by uid 550); 12 Mar 2018 12:44:44 -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 30186 invoked from network); 12 Mar 2018 03:08:04 -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, "Thomas Gleixner" , alan@linux.intel.com, "Dan Williams" , gregkh@linuxfoundation.org, linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, "Kees Cook" , "Al Viro" , "Andi Kleen" , "Linus Torvalds" Date: Mon, 12 Mar 2018 03:06:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 75/76] 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 3.16.56-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 3.16: - Convert several more functions to use __uaccess_begin_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 @@ -433,7 +433,7 @@ do { \ ({ \ int __gu_err; \ unsigned long __gu_val; \ - __uaccess_begin(); \ + __uaccess_begin_nospec(); \ __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ __uaccess_end(); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ @@ -541,7 +541,7 @@ 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 { \ @@ -576,7 +576,7 @@ extern void __cmpxchg_wrong_size(void) __typeof__(ptr) __uval = (uval); \ __typeof__(*(ptr)) __old = (old); \ __typeof__(*(ptr)) __new = (new); \ - __uaccess_begin(); \ + __uaccess_begin_nospec(); \ switch (size) { \ case 1: \ { \ --- a/arch/x86/include/asm/uaccess_32.h +++ b/arch/x86/include/asm/uaccess_32.h @@ -48,19 +48,19 @@ __copy_to_user_inatomic(void __user *to, switch (n) { case 1: - __uaccess_begin(); + __uaccess_begin_nospec(); __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1); __uaccess_end(); return ret; case 2: - __uaccess_begin(); + __uaccess_begin_nospec(); __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2); __uaccess_end(); return ret; case 4: - __uaccess_begin(); + __uaccess_begin_nospec(); __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4); __uaccess_end(); @@ -104,17 +104,17 @@ __copy_from_user_inatomic(void *to, cons switch (n) { case 1: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); __uaccess_end(); return ret; case 2: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); __uaccess_end(); return ret; case 4: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); __uaccess_end(); return ret; @@ -154,17 +154,17 @@ __copy_from_user(void *to, const void __ switch (n) { case 1: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); __uaccess_end(); return ret; case 2: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); __uaccess_end(); return ret; case 4: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); __uaccess_end(); return ret; @@ -182,17 +182,17 @@ static __always_inline unsigned long __c switch (n) { case 1: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u8 *)to, from, 1, ret, 1); __uaccess_end(); return ret; case 2: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u16 *)to, from, 2, ret, 2); __uaccess_end(); return ret; case 4: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_size(*(u32 *)to, from, 4, ret, 4); __uaccess_end(); return ret; --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -57,31 +57,31 @@ int __copy_from_user_nocheck(void *dst, return copy_user_generic(dst, (__force void *)src, size); switch (size) { case 1: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(*(u8 *)dst, (u8 __user *)src, ret, "b", "b", "=q", 1); __uaccess_end(); return ret; case 2: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(*(u16 *)dst, (u16 __user *)src, ret, "w", "w", "=r", 2); __uaccess_end(); return ret; case 4: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(*(u32 *)dst, (u32 __user *)src, ret, "l", "k", "=r", 4); __uaccess_end(); return ret; case 8: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 8); __uaccess_end(); return ret; case 10: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 10); if (likely(!ret)) @@ -91,7 +91,7 @@ int __copy_from_user_nocheck(void *dst, __uaccess_end(); return ret; case 16: - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(*(u64 *)dst, (u64 __user *)src, ret, "q", "", "=r", 16); if (likely(!ret)) @@ -190,7 +190,7 @@ int __copy_in_user(void __user *dst, con switch (size) { case 1: { u8 tmp; - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(tmp, (u8 __user *)src, ret, "b", "b", "=q", 1); if (likely(!ret)) @@ -201,7 +201,7 @@ int __copy_in_user(void __user *dst, con } case 2: { u16 tmp; - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(tmp, (u16 __user *)src, ret, "w", "w", "=r", 2); if (likely(!ret)) @@ -213,7 +213,7 @@ int __copy_in_user(void __user *dst, con case 4: { u32 tmp; - __uaccess_begin(); + __uaccess_begin_nospec(); __get_user_asm(tmp, (u32 __user *)src, ret, "l", "k", "=r", 4); if (likely(!ret)) @@ -224,7 +224,7 @@ int __copy_in_user(void __user *dst, con } case 8: { u64 tmp; - __uaccess_begin(); + __uaccess_begin_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 @@ -570,7 +570,7 @@ do { \ unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned long n) { - __uaccess_begin(); + __uaccess_begin_nospec(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else @@ -583,7 +583,7 @@ EXPORT_SYMBOL(__copy_to_user_ll); unsigned long __copy_from_user_ll(void *to, const void __user *from, unsigned long n) { - __uaccess_begin(); + __uaccess_begin_nospec(); if (movsl_is_ok(to, from, n)) __copy_user_zeroing(to, from, n); else @@ -596,7 +596,7 @@ EXPORT_SYMBOL(__copy_from_user_ll); unsigned long __copy_from_user_ll_nozero(void *to, const void __user *from, unsigned long n) { - __uaccess_begin(); + __uaccess_begin_nospec(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else @@ -610,7 +610,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nozero unsigned long __copy_from_user_ll_nocache(void *to, const void __user *from, unsigned long n) { - __uaccess_begin(); + __uaccess_begin_nospec(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_zeroing_intel_nocache(to, from, n); @@ -627,7 +627,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nocach unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from, unsigned long n) { - __uaccess_begin(); + __uaccess_begin_nospec(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_intel_nocache(to, from, n);