From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932579AbeEHJJg convert rfc822-to-8bit (ORCPT ); Tue, 8 May 2018 05:09:36 -0400 Received: from tyo162.gate.nec.co.jp ([114.179.232.162]:59821 "EHLO tyo162.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754465AbeEHJJe (ORCPT ); Tue, 8 May 2018 05:09:34 -0400 From: Naoya Horiguchi To: "Huang, Ying" CC: Andrew Morton , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Konstantin Khlebnikov , Andrei Vagin , Michal Hocko , Jerome Glisse , Daniel Colascione , Zi Yan , "Kirill A. Shutemov" Subject: Re: [PATCH -mm] mm, pagemap: Hide swap entry for unprivileged users Thread-Topic: [PATCH -mm] mm, pagemap: Hide swap entry for unprivileged users Thread-Index: AQHT5mvVWujS9GcLcU+EklToaBi6vaQk9EkA Date: Tue, 8 May 2018 09:07:34 +0000 Message-ID: <20180508090734.GA27996@hori1.linux.bs1.fc.nec.co.jp> References: <20180508012745.7238-1-ying.huang@intel.com> In-Reply-To: <20180508012745.7238-1-ying.huang@intel.com> Accept-Language: en-US, ja-JP Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.51.8.80] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 08, 2018 at 09:27:45AM +0800, Huang, Ying wrote: > From: Huang Ying > > In ab676b7d6fbf ("pagemap: do not leak physical addresses to > non-privileged userspace"), the /proc/PID/pagemap is restricted to be > readable only by CAP_SYS_ADMIN to address some security issue. In > 1c90308e7a77 ("pagemap: hide physical addresses from non-privileged > users"), the restriction is relieved to make /proc/PID/pagemap > readable, but hide the physical addresses for non-privileged users. > But the swap entries are readable for non-privileged users too. This > has some security issues. For example, for page under migrating, the > swap entry has physical address information. So, in this patch, the > swap entries are hided for non-privileged users too. > > Fixes: 1c90308e7a77 ("pagemap: hide physical addresses from non-privileged users") > Signed-off-by: "Huang, Ying" > Suggested-by: Kirill A. Shutemov > Cc: Konstantin Khlebnikov > Cc: Andrei Vagin > Cc: Michal Hocko > Cc: Jerome Glisse > Cc: Daniel Colascione > Cc: Zi Yan > Cc: Naoya Horiguchi Hi ying huang, This patch looks good to me. Reviewed-by: Naoya Horiguchi > --- > fs/proc/task_mmu.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index a20c6e495bb2..ff947fdd7c71 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -1258,8 +1258,9 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm, > if (pte_swp_soft_dirty(pte)) > flags |= PM_SOFT_DIRTY; > entry = pte_to_swp_entry(pte); > - frame = swp_type(entry) | > - (swp_offset(entry) << MAX_SWAPFILES_SHIFT); > + if (pm->show_pfn) > + frame = swp_type(entry) | > + (swp_offset(entry) << MAX_SWAPFILES_SHIFT); > flags |= PM_SWAP; > if (is_migration_entry(entry)) > page = migration_entry_to_page(entry); > @@ -1310,11 +1311,14 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end, > #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION > else if (is_swap_pmd(pmd)) { > swp_entry_t entry = pmd_to_swp_entry(pmd); > - unsigned long offset = swp_offset(entry); > + unsigned long offset; > > - offset += (addr & ~PMD_MASK) >> PAGE_SHIFT; > - frame = swp_type(entry) | > - (offset << MAX_SWAPFILES_SHIFT); > + if (pm->show_pfn) { > + offset = swp_offset(entry) + > + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > + frame = swp_type(entry) | > + (offset << MAX_SWAPFILES_SHIFT); > + } > flags |= PM_SWAP; > if (pmd_swp_soft_dirty(pmd)) > flags |= PM_SOFT_DIRTY; > @@ -1332,10 +1336,12 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end, > err = add_to_pagemap(addr, &pme, pm); > if (err) > break; > - if (pm->show_pfn && (flags & PM_PRESENT)) > - frame++; > - else if (flags & PM_SWAP) > - frame += (1 << MAX_SWAPFILES_SHIFT); > + if (pm->show_pfn) { > + if (flags & PM_PRESENT) > + frame++; > + else if (flags & PM_SWAP) > + frame += (1 << MAX_SWAPFILES_SHIFT); > + } > } > spin_unlock(ptl); > return err; > -- > 2.17.0 > >