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Date: Tue, 21 Jul 2015 08:11:50 +0000 From: Naoya Horiguchi <n-horiguchi@...jp.nec.com> To: Konstantin Khlebnikov <khlebnikov@...dex-team.ru> CC: "linux-mm@...ck.org" <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, "Kirill A. Shutemov" <kirill@...temov.name>, Mark Williamson <mwilliamson@...o-software.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-api@...r.kernel.org" <linux-api@...r.kernel.org> Subject: Re: [PATCH v4 4/5] pagemap: hide physical addresses from non-privileged users 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 <khlebnikov@...dex-team.ru> > 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 ...) Thanks, Naoya Horiguchi-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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