From patchwork Wed Jun 22 16:22:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirill A . Shutemov" X-Patchwork-Id: 12891144 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 804A3CCA47D for ; Wed, 22 Jun 2022 16:23:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 15F558E00CC; Wed, 22 Jun 2022 12:23:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 10F598E00C9; Wed, 22 Jun 2022 12:23:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ECA2D8E00CC; Wed, 22 Jun 2022 12:23:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id D68BB8E00C9 for ; Wed, 22 Jun 2022 12:23:56 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id AA87435217 for ; Wed, 22 Jun 2022 16:23:56 +0000 (UTC) X-FDA: 79606393272.11.4E7ED34 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by imf26.hostedemail.com (Postfix) with ESMTP id DD10614000B for ; Wed, 22 Jun 2022 16:23:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655915036; x=1687451036; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=OChFIveiqJ9oJhDxBw4UZzfrhSKP5CJTbXz/rUdgIPw=; b=C8uaFVQ+7EWvzq/hOQ5G7usqSPE1+wYfOP+Py77uDTD7RrGAlG66zZsO BgGsbkLHS7Kvme1FtxFN2DUlTY53BA7J3RO3IJlnsecg/UBB25n1ghb9d tuxw/qgDgEFxjk7iHa7kqotsM8E7Zng6CBWIkfP1aMYFLCqXfEBYFdxAF V/cGqh9ObDiXajMa1g+9xGmgGra338zssRTtcjFqu+J3CzBtcBxv4Tpgc QFEktVr1l3obVJMxdL3FvSp1SiW96hKvj5iBtiKrH7UBHXOQnIEIWM51Y RTGAffo/yNsHKUbXSEmt2mAo6clAgjSMD/aKEsGRGt6aTUSxjzCpecENg A==; X-IronPort-AV: E=McAfee;i="6400,9594,10386"; a="260898819" X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="260898819" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 09:22:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="592264461" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga007.fm.intel.com with ESMTP; 22 Jun 2022 09:22:42 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 52A1F36A; Wed, 22 Jun 2022 19:22:43 +0300 (EEST) From: "Kirill A. Shutemov" To: Dave Hansen , Andy Lutomirski , Peter Zijlstra Cc: x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv4 5/8] x86/uaccess: Provide untagged_addr() and remove tags before address check Date: Wed, 22 Jun 2022 19:22:27 +0300 Message-Id: <20220622162230.83474-6-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220622162230.83474-1-kirill.shutemov@linux.intel.com> References: <20220622162230.83474-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=C8uaFVQ+; dmarc=pass (policy=none) header.from=intel.com; spf=temperror (imf26.hostedemail.com: error in processing during lookup of kirill.shutemov@linux.intel.com: DNS error) smtp.mailfrom=kirill.shutemov@linux.intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655915036; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ev8MGGs8S3Cueqe0nVVtgKGrXwNXxOz581QncgpLK/o=; b=STzgW5Ej76omxiZ74fd7kwiDieQT04qWq8fdYTOaoUijeQazAY+1nX1ojdm3ZctwtgLi7h OjNatGC4Kcw2S1xFe+WZQOD84GqZ/7IeiPHxjQVWPTVt1UWUwUW9pa//ByTVBUA8pXPx9d 8e4LcDitvoYE+eqQg82vVYfBvCwHNgk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655915036; a=rsa-sha256; cv=none; b=zI2AJjeZIpueFpfThmn7c9MwluiD3z5IgH+8fkgitu4OeFb0qGut5o3jq8SlXjY2v3ZvFn 2c9kYzJb2sJUiU7DFqntV47QA0FPEMMSO1lBbnbfk/xnpSD0zIaVum4lY/Ga+Yd68yTuDJ zVkjuV2A54IxAoMzqkL1GEb6wzjfoBA= X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: DD10614000B X-Rspam-User: Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=C8uaFVQ+; dmarc=pass (policy=none) header.from=intel.com; spf=temperror (imf26.hostedemail.com: error in processing during lookup of kirill.shutemov@linux.intel.com: DNS error) smtp.mailfrom=kirill.shutemov@linux.intel.com X-Stat-Signature: kxf4w6i3k6pa85pbk9qs9ucjfteh7nsr X-HE-Tag: 1655915035-763099 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: untagged_addr() is a helper used by the core-mm to strip tag bits and get the address to the canonical shape. In only handles userspace addresses. The untagging mask is stored in mmu_context and will be set on enabling LAM for the process. The tags must not be included into check whether it's okay to access the userspace address. Strip tags in access_ok(). get_user() and put_user() don't use access_ok(), but check access against TASK_SIZE directly in assembly. Strip tags, before calling into the assembly helper. Signed-off-by: Kirill A. Shutemov --- arch/x86/include/asm/mmu.h | 1 + arch/x86/include/asm/mmu_context.h | 11 ++++++++ arch/x86/include/asm/uaccess.h | 42 +++++++++++++++++++++++++++--- arch/x86/kernel/process.c | 3 +++ 4 files changed, 54 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index d150e92163b6..59c617fc7c6f 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -41,6 +41,7 @@ typedef struct { #ifdef CONFIG_X86_64 unsigned short flags; u64 lam_cr3_mask; + u64 untag_mask; #endif struct mutex lock; diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index e6eac047c728..05821534aadc 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -100,6 +100,12 @@ static inline u64 mm_cr3_lam_mask(struct mm_struct *mm) static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm) { mm->context.lam_cr3_mask = oldmm->context.lam_cr3_mask; + mm->context.untag_mask = oldmm->context.untag_mask; +} + +static inline void mm_reset_untag_mask(struct mm_struct *mm) +{ + mm->context.untag_mask = -1UL; } #else @@ -112,6 +118,10 @@ static inline u64 mm_cr3_lam_mask(struct mm_struct *mm) static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm) { } + +static inline void mm_reset_untag_mask(struct mm_struct *mm) +{ +} #endif #define enter_lazy_tlb enter_lazy_tlb @@ -138,6 +148,7 @@ static inline int init_new_context(struct task_struct *tsk, mm->context.execute_only_pkey = -1; } #endif + mm_reset_untag_mask(mm); init_new_context_ldt(mm); return 0; } diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 913e593a3b45..803241dfc473 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -6,6 +6,7 @@ */ #include #include +#include #include #include #include @@ -20,6 +21,30 @@ static inline bool pagefault_disabled(void); # define WARN_ON_IN_IRQ() #endif +#ifdef CONFIG_X86_64 +/* + * Mask out tag bits from the address. + * + * Magic with the 'sign' allows to untag userspace pointer without any branches + * while leaving kernel addresses intact. + */ +#define untagged_addr(mm, addr) ({ \ + u64 __addr = (__force u64)(addr); \ + s64 sign = (s64)__addr >> 63; \ + __addr &= (mm)->context.untag_mask | sign; \ + (__force __typeof__(addr))__addr; \ +}) + +#define untagged_ptr(mm, ptr) ({ \ + u64 __ptrval = (__force u64)(ptr); \ + __ptrval = untagged_addr(mm, __ptrval); \ + (__force __typeof__(*(ptr)) *)__ptrval; \ +}) +#else +#define untagged_addr(mm, addr) (addr) +#define untagged_ptr(mm, ptr) (ptr) +#endif + /** * access_ok - Checks if a user space pointer is valid * @addr: User space pointer to start of block to check @@ -40,7 +65,7 @@ static inline bool pagefault_disabled(void); #define access_ok(addr, size) \ ({ \ WARN_ON_IN_IRQ(); \ - likely(__access_ok(addr, size)); \ + likely(__access_ok(untagged_addr(current->mm, addr), size)); \ }) #include @@ -125,7 +150,13 @@ extern int __get_user_bad(void); * Return: zero on success, or -EFAULT on error. * On error, the variable @x is set to zero. */ -#define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); }) +#define get_user(x,ptr) \ +({ \ + __typeof__(*(ptr)) __user *__ptr_clean; \ + __ptr_clean = untagged_ptr(current->mm, ptr); \ + might_fault(); \ + do_get_user_call(get_user,x,__ptr_clean); \ +}) /** * __get_user - Get a simple variable from user space, with less checking. @@ -222,7 +253,12 @@ extern void __put_user_nocheck_8(void); * * Return: zero on success, or -EFAULT on error. */ -#define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) +#define put_user(x, ptr) ({ \ + __typeof__(*(ptr)) __user *__ptr_clean; \ + __ptr_clean = untagged_ptr(current->mm, ptr); \ + might_fault(); \ + do_put_user_call(put_user,x,__ptr_clean); \ +}) /** * __put_user - Write a simple value into user space, with less checking. diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 9b2772b7e1f3..18b2bfdf7b9b 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -47,6 +47,7 @@ #include #include #include +#include #include "process.h" @@ -367,6 +368,8 @@ void arch_setup_new_exec(void) task_clear_spec_ssb_noexec(current); speculation_ctrl_update(read_thread_flags()); } + + mm_reset_untag_mask(current->mm); } #ifdef CONFIG_X86_IOPL_IOPERM