From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Add vm_ops()->mprotect() for additional constraints for a VMA.
Intel Software Guard eXtensions (SGX) will use this callback to add two
constraints:
1. Verify that the address range does not have holes: each page address
must be filled with an enclave page.
2. Verify that VMA permissions won't surpass the permissions of any enclave
page within the address range. Enclave cryptographically sealed
permissions for each page address that set the upper limit for possible
VMA permissions. Not respecting this can cause #GP's to be emitted.
Cc: linux-mm@xxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Acked-by: Jethro Beekman <jethro@xxxxxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
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 dc7b87310c10..fc0e3ef28873 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -542,6 +542,8 @@ 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 (*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 ce8b8a5eacbb..e23dfd8d18bc 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -603,13 +603,20 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
goto out;
}
+ tmp = vma->vm_end;
+ if (tmp > end)
+ tmp = end;
+
error = security_file_mprotect(vma, reqprot, prot);
if (error)
goto out;
- tmp = vma->vm_end;
- if (tmp > end)
- tmp = end;
+ if (vma->vm_ops && vma->vm_ops->mprotect) {
+ error = vma->vm_ops->mprotect(vma, nstart, tmp, prot);
+ if (error)
+ goto out;
+ }
+
error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
if (error)
goto out;
--
2.25.1
