[PATCHv3 03/17] mm/ksm: Do not merge pages with different KeyIDs

Kirill A. Shutemov
2018-06-12T14:42:51Z

Pages encrypted with different encryption keys are not subject to KSM
merge. Otherwise it would cross security boundary.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/mm.h | 7 +++++++
mm/ksm.c | 3 +++
2 files changed, 10 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 435b053c457c..ac1a8480284d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1506,6 +1506,13 @@ static inline int vma_keyid(struct vm_area_struct *vma)
}
#endif

+#ifndef page_keyid
+static inline int page_keyid(struct page *page)
+{
+ return 0;
+}
+#endif
+
#ifdef CONFIG_SHMEM
/*
* The vma_is_shmem is not inline because it is used only by slow
diff --git a/mm/ksm.c b/mm/ksm.c
index 7d6558f3bac9..db94bd45fe66 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1201,6 +1201,9 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
if (!PageAnon(page))
goto out;

+ if (page_keyid(page) != page_keyid(kpage))
+ goto out;
+
/*
* We need the page lock to read a stable PageSwapCache in
* write_protect_page(). We use trylock_page() instead of
--
2.17.1