| From | "Kirill A. Shutemov" <> | Subject | [PATCH, RFC 47/62] mm: Restrict MKTME memory encryption to anonymous VMAs | Date | Wed, 8 May 2019 17:44:07 +0300 |
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From: Alison Schofield <alison.schofield@intel.com>
Memory encryption is only supported for mappings that are ANONYMOUS. Test the 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 <kirill.shutemov@linux.intel.com> --- mm/mprotect.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c index 38d766b5cc20..53bd41f99a67 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -346,6 +346,24 @@ 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. + * If this test fails on any single VMA, the entire mprotect + * request fails. + */ +static 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, @@ -532,6 +550,12 @@ 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; -- 2.20.1
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