lkml.org 
[lkml]   [2015]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v4 4/5] pagemap: hide physical addresses from non-privileged users
    From
    Reviewed-by: Mark Williamson <mwilliamson@undo-software.com>

    On Tue, Jul 21, 2015 at 9:39 AM, Konstantin Khlebnikov <koct9i@gmail.com> wrote:
    > On Tue, Jul 21, 2015 at 11:11 AM, Naoya Horiguchi
    > <n-horiguchi@ah.jp.nec.com> 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 <khlebnikov@yandex-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 ...)
    >
    > 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: <a hrefmailto:"dont@kvack.org"> email@kvack.org </a>


    \
     
     \ /
      Last update: 2015-07-24 20:41    [W:3.506 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site