[PATCH v15 18/26] integrity: Add optional callback function to integrity_inode_free()

[Stefan Berger <stefanb@xxxxxxxxxxxxx>]

Add an optional callback function to integrity_inode_free() that,
if provided, must be called and determines whether the iint can be
freed. Adjust all callers of this function to provide a NULL pointer
since none of the existing callers needs this check.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
 include/linux/integrity.h |  8 ++++++--
 security/integrity/iint.c | 15 +++++++++++++--
 security/security.c       |  2 +-
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/include/linux/integrity.h b/include/linux/integrity.h
index 2ea0f2f65ab6..9fe826b9146e 100644
--- a/include/linux/integrity.h
+++ b/include/linux/integrity.h
@@ -19,10 +19,13 @@ enum integrity_status {
 	INTEGRITY_UNKNOWN,
 };
 
+struct integrity_iint_cache;
+typedef bool (*iint_removable_cb)(struct integrity_iint_cache *iint);
+
 /* List of EVM protected security xattrs */
 #ifdef CONFIG_INTEGRITY
 extern struct integrity_iint_cache *integrity_inode_get(struct inode *inode);
-extern void integrity_inode_free(struct inode *inode);
+extern void integrity_inode_free(struct inode *inode, iint_removable_cb check);
 extern void __init integrity_load_keys(void);
 
 #else
@@ -32,7 +35,8 @@ static inline struct integrity_iint_cache *
 	return NULL;
 }
 
-static inline void integrity_inode_free(struct inode *inode)
+static inline void integrity_inode_free(struct inode *inode,
+					iint_removable_cb check)
 {
 	return;
 }
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 371cbceaf479..4580df0e716e 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -143,21 +143,32 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
 /**
  * integrity_inode_free - called on security_inode_free
  * @inode: pointer to the inode
+ * @check: optional callback function to check whether the iint can be freed
  *
  * Free the integrity information(iint) associated with an inode.
  */
-void integrity_inode_free(struct inode *inode)
+void integrity_inode_free(struct inode *inode, iint_removable_cb check)
 {
 	struct integrity_iint_cache *iint;
+	bool freeit = true;
 
 	if (!IS_IMA(inode))
 		return;
 
 	write_lock(&integrity_iint_lock);
+
 	iint = __integrity_iint_find(inode);
-	rb_erase(&iint->rb_node, &integrity_iint_tree);
+
+	if (check)
+		freeit = check(iint);
+	if (freeit)
+		rb_erase(&iint->rb_node, &integrity_iint_tree);
+
 	write_unlock(&integrity_iint_lock);
 
+	if (!freeit)
+		return;
+
 	ima_free_ns_status_list(&iint->ns_list, &iint->ns_list_lock);
 
 	iint_free(iint);
diff --git a/security/security.c b/security/security.c
index d1571900a8c7..2b1f9ec8dea9 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1071,7 +1071,7 @@ static void inode_free_by_rcu(struct rcu_head *head)
 
 void security_inode_free(struct inode *inode)
 {
-	integrity_inode_free(inode);
+	integrity_inode_free(inode, NULL);
 	call_void_hook(inode_free_security, inode);
 	/*
 	 * The inode may still be referenced in a path walk and
-- 
2.37.3