Integrity: IMA file free imbalance

The number of calls to ima_path_check()/ima_file_free()
should be balanced.  An extra call to fput(), indicates
the file could have been accessed without first being
measured.

Although f_count is incremented/decremented in places other
than fget/fput, like fget_light/fput_light and get_file, the
current task must already hold a file refcnt.  The call to
__fput() is delayed until the refcnt becomes 0, resulting
in ima_file_free() flagging any changes.

- add hook to increment opencount for IPC shared memory(SYSV),
  shmat files, and /dev/zero
- moved NULL iint test in opencount_get()

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
index 750db3c993a7..1f035e8d29c7 100644
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -126,6 +126,7 @@ struct ima_iint_cache *ima_iint_find_insert_get(struct inode *inode)
 
         return iint;
 }
+EXPORT_SYMBOL_GPL(ima_iint_find_insert_get);
 
 /* iint_free - called when the iint refcount goes to zero */
 void iint_free(struct kref *kref)
@@ -134,6 +135,21 @@ void iint_free(struct kref *kref)
                                                    refcount);
         iint->version = 0;
         iint->flags = 0UL;
+        if (iint->readcount != 0) {
+                printk(KERN_INFO "%s: readcount: %ld\n", __FUNCTION__,
+                       iint->readcount);
+                iint->readcount = 0;
+        }
+        if (iint->writecount != 0) {
+                printk(KERN_INFO "%s: writecount: %ld\n", __FUNCTION__,
+                       iint->writecount);
+                iint->writecount = 0;
+        }
+        if (iint->opencount != 0) {
+                printk(KERN_INFO "%s: opencount: %ld\n", __FUNCTION__,
+                       iint->opencount);
+                iint->opencount = 0;
+        }
         kref_set(&iint->refcount, 1);
         kmem_cache_free(iint_cache, iint);
 }
@@ -174,6 +190,7 @@ static void init_once(void *foo)
         mutex_init(&iint->mutex);
         iint->readcount = 0;
         iint->writecount = 0;
+        iint->opencount = 0;
         kref_set(&iint->refcount, 1);
 }