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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 8D777C43441 for ; Sun, 11 Nov 2018 20:21:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5AA3020854 for ; Sun, 11 Nov 2018 20:21:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5AA3020854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731319AbeKLGKf (ORCPT ); Mon, 12 Nov 2018 01:10:35 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53518 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731963AbeKLGKJ (ORCPT ); Mon, 12 Nov 2018 01:10:09 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gLvt3-0000l7-Dh; Sun, 11 Nov 2018 19:59:13 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gLvsR-0001Ws-KM; Sun, 11 Nov 2018 19:58:35 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Mark Williamson" , "Linus Torvalds" , "Naoya Horiguchi" , "Konstantin Khlebnikov" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 124/366] pagemap: hide physical addresses from non-privileged users In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit 1c90308e7a77af6742a97d1021cca923b23b7f0d upstream. This patch makes pagemap readable for normal users and hides physical addresses from them. For some use-cases PFN isn't required at all. See http://lkml.kernel.org/r/1425935472-17949-1-git-send-email-kirill@shutemov.name Fixes: ab676b7d6fbf ("pagemap: do not leak physical addresses to non-privileged userspace") Signed-off-by: Konstantin Khlebnikov Cc: Naoya Horiguchi Reviewed-by: Mark Williamson Tested-by: Mark Williamson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.16: - Add the same check in the places where we look up a PFN - Adjust context] Signed-off-by: Ben Hutchings --- fs/proc/task_mmu.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -862,6 +862,7 @@ struct pagemapread { int pos, len; /* units: PM_ENTRY_BYTES, not bytes */ pagemap_entry_t *buffer; bool v2; + bool show_pfn; }; #define PAGEMAP_WALK_SIZE (PMD_SIZE) @@ -921,12 +922,13 @@ static int pagemap_pte_hole(unsigned lon static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, struct vm_area_struct *vma, unsigned long addr, pte_t pte) { - u64 frame, flags; + u64 frame = 0, flags; struct page *page = NULL; int flags2 = 0; 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)) @@ -966,7 +968,7 @@ static void thp_pmd_to_pagemap_entry(pag * This if-check is just to prepare for future implementation. */ if (pmd_present(pmd)) - *pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset) + *pme = make_pme((pm->show_pfn ? PM_PFRAME(pmd_pfn(pmd) + offset) : 0) | PM_STATUS2(pm->v2, pmd_flags2) | PM_PRESENT); else *pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, pmd_flags2)); @@ -1075,7 +1077,7 @@ static void huge_pte_to_pagemap_entry(pa pte_t pte, int offset, int flags2) { if (pte_present(pte)) - *pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset) | + *pme = make_pme((pm->show_pfn ? PM_PFRAME(pte_pfn(pte) + offset) : 0) | PM_STATUS2(pm->v2, flags2) | PM_PRESENT); else @@ -1167,6 +1169,10 @@ static ssize_t pagemap_read(struct file goto out_task; pm.v2 = soft_dirty_cleared; + + /* do not disclose physical addresses: attack vector */ + pm.show_pfn = file_ns_capable(file, &init_user_ns, CAP_SYS_ADMIN); + pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT); pm.buffer = kmalloc(pm.len * PM_ENTRY_BYTES, GFP_TEMPORARY); ret = -ENOMEM; @@ -1241,9 +1247,6 @@ out: static int pagemap_open(struct inode *inode, struct file *file) { - /* do not disclose physical addresses: attack vector */ - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; pr_warn_once("Bits 55-60 of /proc/PID/pagemap entries are about " "to stop being page-shift some time soon. See the " "linux/Documentation/vm/pagemap.txt for details.\n");