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

    https://people.kernel.org/tglx/notes-about-netiquette

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