Re: [PATCH v22 11/24] mm: Introduce vm_ops->may_mprotect()

Borislav Petkov
2019-10-08T17:41:30Z

+ linux-mm.

On Tue, Sep 03, 2019 at 05:26:42PM +0300, Jarkko Sakkinen wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> Add vm_ops()->may_mprotect() to check additional constrains set by a

constraints

Leaving in the rest for MM folks:

> subsystem for a mprotect() call.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> include/linux/mm.h | 2 ++
> mm/mprotect.c | 13 ++++++++++---
> 2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0334ca97c584..405cea65057a 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -469,6 +469,8 @@ struct vm_operations_struct {
> void (*close)(struct vm_area_struct * area);
> int (*split)(struct vm_area_struct * area, unsigned long addr);
> int (*mremap)(struct vm_area_struct * area);
> + int (*may_mprotect)(struct vm_area_struct *vma, unsigned long start,
> + unsigned long end, unsigned long prot);
> vm_fault_t (*fault)(struct vm_fault *vmf);
> vm_fault_t (*huge_fault)(struct vm_fault *vmf,
> enum page_entry_size pe_size);
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index bf38dfbbb4b4..18732543b295 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -547,13 +547,20 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
> goto out;
> }
>
> + tmp = vma->vm_end;
> + if (tmp > end)
> + tmp = end;
> +
> + if (vma->vm_ops && vma->vm_ops->may_mprotect) {
> + error = vma->vm_ops->may_mprotect(vma, nstart, tmp, prot);
> + if (error)
> + goto out;
> + }
> +
> error = security_file_mprotect(vma, reqprot, prot);
> if (error)
> goto out;
>
> - tmp = vma->vm_end;
> - if (tmp > end)
> - tmp = end;
> error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
> if (error)
> goto out;
> --
> 2.20.1
>

--
Regards/Gruss,
Boris.