From: Jeff Xu <jeffxu@xxxxxxxxxxxx>
Two utilities to be used later.
can_modify_mm:
checks sealing flags for given memory range.
can_modify_vma:
checks sealing flags for given vma.
Signed-off-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
---
include/linux/mm.h | 18 ++++++++++++++++++
mm/mseal.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 56 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3d1120570de5..2435acc1f44f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3339,6 +3339,12 @@ static inline unsigned long vma_seals(struct vm_area_struct *vma)
return (vma->vm_seals & MM_SEAL_ALL);
}
+extern bool can_modify_mm(struct mm_struct *mm, unsigned long start,
+ unsigned long end, unsigned long checkSeals);
+
+extern bool can_modify_vma(struct vm_area_struct *vma,
+ unsigned long checkSeals);
+
#else
static inline bool check_vma_seals_mergeable(unsigned long vm_seals1)
{
@@ -3349,6 +3355,18 @@ static inline unsigned long vma_seals(struct vm_area_struct *vma)
{
return 0;
}
+
+static inline bool can_modify_mm(struct mm_struct *mm, unsigned long start,
+ unsigned long end, unsigned long checkSeals)
+{
+ return true;
+}
+
+static inline bool can_modify_vma(struct vm_area_struct *vma,
+ unsigned long checkSeals)
+{
+ return true;
+}
#endif
/* These take the mm semaphore themselves */
diff --git a/mm/mseal.c b/mm/mseal.c
index 13bbe9ef5883..d12aa628ebdc 100644
--- a/mm/mseal.c
+++ b/mm/mseal.c
@@ -26,6 +26,44 @@ static bool can_do_mseal(unsigned long types, unsigned long flags)
return true;
}
+/*
+ * check if a vma is sealed for modification.
+ * return true, if modification is allowed.
+ */
+bool can_modify_vma(struct vm_area_struct *vma,
+ unsigned long checkSeals)
+{
+ if (checkSeals & vma_seals(vma))
+ return false;
+
+ return true;
+}
+
+/*
+ * Check if the vmas of a memory range are allowed to be modified.
+ * the memory ranger can have a gap (unallocated memory).
+ * return true, if it is allowed.
+ */
+bool can_modify_mm(struct mm_struct *mm, unsigned long start, unsigned long end,
+ unsigned long checkSeals)
+{
+ struct vm_area_struct *vma;
+
+ VMA_ITERATOR(vmi, mm, start);
+
+ if (!checkSeals)
+ return true;
+
+ /* going through each vma to check. */
+ for_each_vma_range(vmi, vma, end) {
+ if (!can_modify_vma(vma, checkSeals))
+ return false;
+ }
+
+ /* Allow by default. */
+ return true;
+}
+
/*
* Check if a seal type can be added to VMA.
*/
--
2.43.0.472.g3155946c3a-goog
