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 X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 338AEC33CA9 for ; Mon, 13 Jan 2020 19:11:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EB95222C4 for ; Mon, 13 Jan 2020 19:11:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728920AbgAMTJl (ORCPT ); Mon, 13 Jan 2020 14:09:41 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:39869 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728836AbgAMTJf (ORCPT ); Mon, 13 Jan 2020 14:09:35 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1ir55f-0000xD-Sg; Mon, 13 Jan 2020 20:09:32 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 8EA941C18DC; Mon, 13 Jan 2020 20:09:26 +0100 (CET) Date: Mon, 13 Jan 2020 19:09:26 -0000 From: "tip-bot2 for Dmitry Safonov" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/core] x86/vdso: Handle faults on timens page Cc: Andrei Vagin , Dmitry Safonov , Thomas Gleixner , x86 , LKML In-Reply-To: <20191112012724.250792-25-dima@arista.com> References: <20191112012724.250792-25-dima@arista.com> MIME-Version: 1.0 Message-ID: <157894256643.19145.12197846390131767365.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the timers/core branch of tip: Commit-ID: ad22c315d67e713e4e107f9db2b7c27e2a245377 Gitweb: https://git.kernel.org/tip/ad22c315d67e713e4e107f9db2b7c27e2a245377 Author: Dmitry Safonov AuthorDate: Tue, 12 Nov 2019 01:27:13 Committer: Thomas Gleixner CommitterDate: Mon, 13 Jan 2020 08:10:56 +01:00 x86/vdso: Handle faults on timens page If a task belongs to a time namespace then the VVAR page which contains the system wide VDSO data is replaced with a namespace specific page which has the same layout as the VVAR page. Co-developed-by: Andrei Vagin Signed-off-by: Andrei Vagin Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20191112012724.250792-25-dima@arista.com --- arch/x86/entry/vdso/vma.c | 54 ++++++++++++++++++++++++++++++++++++-- mm/mmap.c | 2 +- 2 files changed, 54 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 04e3498..e5f3361 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -14,11 +14,14 @@ #include #include #include +#include + #include #include #include #include #include +#include #include #include #include @@ -107,10 +110,36 @@ static int vvar_mremap(const struct vm_special_mapping *sm, return 0; } +#ifdef CONFIG_TIME_NS +static struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + if (likely(vma->vm_mm == current->mm)) + return current->nsproxy->time_ns->vvar_page; + + /* + * VM_PFNMAP | VM_IO protect .fault() handler from being called + * through interfaces like /proc/$pid/mem or + * process_vm_{readv,writev}() as long as there's no .access() + * in special_mapping_vmops(). + * For more details check_vma_flags() and __access_remote_vm() + */ + + WARN(1, "vvar_page accessed remotely"); + + return NULL; +} +#else +static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + return NULL; +} +#endif + static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) { const struct vdso_image *image = vma->vm_mm->context.vdso_image; + unsigned long pfn; long sym_offset; if (!image) @@ -130,8 +159,21 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, return VM_FAULT_SIGBUS; if (sym_offset == image->sym_vvar_page) { - return vmf_insert_pfn(vma, vmf->address, - __pa_symbol(&__vvar_page) >> PAGE_SHIFT); + struct page *timens_page = find_timens_vvar_page(vma); + + pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT; + + /* + * If a task belongs to a time namespace then a namespace + * specific VVAR is mapped with the sym_vvar_page offset and + * the real VVAR page is mapped with the sym_timens_page + * offset. + * See also the comment near timens_setup_vdso_data(). + */ + if (timens_page) + pfn = page_to_pfn(timens_page); + + return vmf_insert_pfn(vma, vmf->address, pfn); } else if (sym_offset == image->sym_pvclock_page) { struct pvclock_vsyscall_time_info *pvti = pvclock_get_pvti_cpu0_va(); @@ -146,6 +188,14 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK)) return vmf_insert_pfn(vma, vmf->address, virt_to_phys(tsc_pg) >> PAGE_SHIFT); + } else if (sym_offset == image->sym_timens_page) { + struct page *timens_page = find_timens_vvar_page(vma); + + if (!timens_page) + return VM_FAULT_SIGBUS; + + pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT; + return vmf_insert_pfn(vma, vmf->address, pfn); } return VM_FAULT_SIGBUS; diff --git a/mm/mmap.c b/mm/mmap.c index 9c64852..60c17d3 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3342,6 +3342,8 @@ static const struct vm_operations_struct special_mapping_vmops = { .fault = special_mapping_fault, .mremap = special_mapping_mremap, .name = special_mapping_name, + /* vDSO code relies that VVAR can't be accessed remotely */ + .access = NULL, }; static const struct vm_operations_struct legacy_special_mapping_vmops = {