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mm: /proc/pid/pagemap: hide swap entries from unprivileged users

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[ Upstream commit ab6ecf247a ]

In commit ab676b7d6f ("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 commit 1c90308e7a ("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.

Link: http://lkml.kernel.org/r/20180508012745.7238-1-ying.huang@intel.com
Fixes: 1c90308e7a ("pagemap: hide physical addresses from non-privileged users")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Huang Ying 2018-06-07 17:07:39 -07:00 committed by Greg Kroah-Hartman
parent 9691035cbf
commit 9e1a1fc0cd
1 changed files with 16 additions and 10 deletions
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26
fs/proc/task_mmu.c
View file

@ -1275,8 +1275,9 @@ 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);
@ -1327,11 +1328,14 @@ 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;
@ -1349,10 +1353,12 @@ 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;