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Subject[PATCH v22 11/24] mm: Introduce vm_ops->may_mprotect()
Date
From: Sean Christopherson <sean.j.christopherson@intel.com>

Add vm_ops()->may_mprotect() to check additional constrains set by a
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
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