[RFC v2 09/13] mm: Restrict memory encryption to anonymous VMA's
From: Alison Schofield <alison.schofield@intel.com>
Date: 2018-12-04 07:37:27
Also in:
keyrings, linux-mm
Subsystem:
memory management, memory mapping, the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
Memory encryption is only supported for mappings that are ANONYMOUS. Test the entire range of VMA's in an encrypt_mprotect() request to make sure they all meet that requirement before encrypting any. The encrypt_mprotect syscall will return -EINVAL and will not encrypt any VMA's if this check fails. Signed-off-by: Alison Schofield <alison.schofield@intel.com> Signed-off-by: Kirill A. Shutemov <redacted> --- mm/mprotect.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ad8127dc9aac..f1c009409134 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c@@ -345,6 +345,24 @@ static int prot_none_walk(struct vm_area_struct *vma, unsigned long start, return walk_page_range(start, end, &prot_none_walk); } +/* + * Encrypted mprotect is only supported on anonymous mappings. + * All VMA's in the requested range must be anonymous. If this + * test fails on any single VMA, the entire mprotect request fails. + */ +bool mem_supports_encryption(struct vm_area_struct *vma, unsigned long end) +{ + struct vm_area_struct *test_vma = vma; + + do { + if (!vma_is_anonymous(test_vma)) + return false; + + test_vma = test_vma->vm_next; + } while (test_vma && test_vma->vm_start < end); + return true; +} + int mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long start, unsigned long end, unsigned long newflags,
@@ -531,6 +549,12 @@ static int do_mprotect_ext(unsigned long start, size_t len, goto out; } } + + if (keyid > 0 && !mem_supports_encryption(vma, end)) { + error = -EINVAL; + goto out; + } + if (start > vma->vm_start) prev = vma;
--
2.14.1