From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f53.google.com (mail-la0-f53.google.com [209.85.215.53]) by kanga.kvack.org (Postfix) with ESMTP id DE6706B0253 for ; Fri, 24 Jul 2015 14:18:19 -0400 (EDT) Received: by lahh5 with SMTP id h5so18788685lah.2 for ; Fri, 24 Jul 2015 11:18:19 -0700 (PDT) Received: from mail-la0-f54.google.com (mail-la0-f54.google.com. [209.85.215.54]) by mx.google.com with ESMTPS id bb9si8196604lab.89.2015.07.24.11.18.17 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Jul 2015 11:18:18 -0700 (PDT) Received: by lahh5 with SMTP id h5so18788292lah.2 for ; Fri, 24 Jul 2015 11:18:17 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20150714152516.29844.69929.stgit@buzz> <20150714153747.29844.13543.stgit@buzz> <20150721081149.GC4490@hori1.linux.bs1.fc.nec.co.jp> Date: Fri, 24 Jul 2015 19:18:17 +0100 Message-ID: Subject: Re: [PATCH v4 4/5] pagemap: hide physical addresses from non-privileged users From: Mark Williamson Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Konstantin Khlebnikov Cc: Naoya Horiguchi , Konstantin Khlebnikov , "linux-mm@kvack.org" , Andrew Morton , "Kirill A. Shutemov" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" Reviewed-by: Mark Williamson On Tue, Jul 21, 2015 at 9:39 AM, Konstantin Khlebnikov wrote: > On Tue, Jul 21, 2015 at 11:11 AM, Naoya Horiguchi > wrote: >> On Tue, Jul 14, 2015 at 06:37:47PM +0300, Konstantin Khlebnikov wrote: >>> This patch makes pagemap readable for normal users and hides physical >>> addresses from them. For some use-cases PFN isn't required at all. >>> >>> Signed-off-by: Konstantin Khlebnikov >>> Fixes: ab676b7d6fbf ("pagemap: do not leak physical addresses to non-privileged userspace") >>> Link: http://lkml.kernel.org/r/1425935472-17949-1-git-send-email-kirill@shutemov.name >>> --- >>> fs/proc/task_mmu.c | 25 ++++++++++++++----------- >>> 1 file changed, 14 insertions(+), 11 deletions(-) >>> >>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c >>> index 040721fa405a..3a5d338ea219 100644 >>> --- a/fs/proc/task_mmu.c >>> +++ b/fs/proc/task_mmu.c >>> @@ -937,6 +937,7 @@ typedef struct { >>> struct pagemapread { >>> int pos, len; /* units: PM_ENTRY_BYTES, not bytes */ >>> pagemap_entry_t *buffer; >>> + bool show_pfn; >>> }; >>> >>> #define PAGEMAP_WALK_SIZE (PMD_SIZE) >>> @@ -1013,7 +1014,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm, >>> struct page *page = NULL; >>> >>> if (pte_present(pte)) { >>> - frame = pte_pfn(pte); >>> + if (pm->show_pfn) >>> + frame = pte_pfn(pte); >>> flags |= PM_PRESENT; >>> page = vm_normal_page(vma, addr, pte); >>> if (pte_soft_dirty(pte)) >> >> Don't you need the same if (pm->show_pfn) check in is_swap_pte path, too? >> (although I don't think that it can be exploited by row hammer attack ...) > > Yeah, but I see no reason for that. > Probably except swap on ramdrive, but this too weird =) > >> >> Thanks, >> Naoya Horiguchi >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org