On Fri, 2018-09-07 at 15:37 -0700, Alison Schofield wrote:
> 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@xxxxxxxxx>
> ---
> mm/mprotect.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 6c2e1106525c..3384b755aad1 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -311,6 +311,24 @@ unsigned long change_protection(struct vm_area_struct
> *vma, unsigned long start,
> return pages;
> }
>
> +/*
> + * 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.
> + */
kdoc
> +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,
> @@ -491,6 +509,10 @@ 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;
>
/Jarkko
