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, 2 insertions, 0 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index f1b0d4871f3a..dd5588f5d939 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -51,6 +51,7 @@
 #include <linux/highmem.h>
 #include <linux/seq_file.h>
 #include <linux/magic.h>
+#include <linux/ima.h>
 
 #include <asm/uaccess.h>
 #include <asm/div64.h>
@@ -2600,6 +2601,7 @@ int shmem_zero_setup(struct vm_area_struct *vma)
         if (IS_ERR(file))
                 return PTR_ERR(file);
 
+        ima_shm_check(file);
         if (vma->vm_file)
                 fput(vma->vm_file);
         vma->vm_file = file;