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, 3 insertions, 0 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index 38a055758a9b..d39bd7637b1c 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -39,6 +39,7 @@
 #include <linux/nsproxy.h>
 #include <linux/mount.h>
 #include <linux/ipc_namespace.h>
+#include <linux/ima.h>
 
 #include <asm/uaccess.h>
 
@@ -381,6 +382,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
         error = PTR_ERR(file);
         if (IS_ERR(file))
                 goto no_file;
+        ima_shm_check(file);
 
         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
         if (id < 0) {
@@ -888,6 +890,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
         file = alloc_file(path.mnt, path.dentry, f_mode, &shm_file_operations);
         if (!file)
                 goto out_free;
+        ima_shm_check(file);
 
         file->private_data = sfd;
         file->f_mapping = shp->shm_file->f_mapping;