integrity: add ima_counts_put (updated)

This patch fixes an imbalance message as reported by J.R. Okajima.
The IMA file counters are incremented in ima_path_check. If the
actual open fails, such as ETXTBSY, decrement the counters to
prevent unnecessary imbalance messages.

Reported-by: J.R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

3 files changed, 41 insertions, 1 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 5b961eb71cbf..f3c5b278895a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1761,6 +1761,10 @@ do_last:
                         goto exit;
                 }
                 filp = nameidata_to_filp(&nd, open_flag);
+                if (IS_ERR(filp))
+                        ima_counts_put(&nd.path,
+                                       acc_mode & (MAY_READ | MAY_WRITE |
+                                                   MAY_EXEC));
                 mnt_drop_write(nd.path.mnt);
                 if (nd.root.mnt)
                         path_put(&nd.root);
@@ -1817,6 +1821,9 @@ ok:
                 goto exit;
         }
         filp = nameidata_to_filp(&nd, open_flag);
+        if (IS_ERR(filp))
+                ima_counts_put(&nd.path,
+                               acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC));
         /*
          * It is now safe to drop the mnt write
          * because the filp has had a write taken
diff --git a/include/linux/ima.h b/include/linux/ima.h
index b1b827d091a9..0e3f2a4c25f6 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -24,6 +24,7 @@ extern int ima_path_check(struct path *path, int mask, int update_counts);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
 extern void ima_counts_get(struct file *file);
+extern void ima_counts_put(struct path *path, int mask);
 
 #else
 static inline int ima_bprm_check(struct linux_binprm *bprm)
@@ -60,5 +61,10 @@ static inline void ima_counts_get(struct file *file)
 {
         return;
 }
+
+static inline void ima_counts_put(struct path *path, int mask)
+{
+        return;
+}
 #endif /* CONFIG_IMA_H */
 #endif /* _LINUX_IMA_H */
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 6f611874d10e..101c512564ec 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -238,7 +238,34 @@ out:
 }
 
 /*
- * ima_opens_get - increment file counts
+ * ima_counts_put - decrement file counts
+ *
+ * File counts are incremented in ima_path_check. On file open
+ * error, such as ETXTBSY, decrement the counts to prevent
+ * unnecessary imbalance messages.
+ */
+void ima_counts_put(struct path *path, int mask)
+{
+        struct inode *inode = path->dentry->d_inode;
+        struct ima_iint_cache *iint;
+
+        if (!ima_initialized || !S_ISREG(inode->i_mode))
+                return;
+        iint = ima_iint_find_insert_get(inode);
+        if (!iint)
+                return;
+
+        mutex_lock(&iint->mutex);
+        iint->opencount--;
+        if ((mask & MAY_WRITE) || (mask == 0))
+                iint->writecount--;
+        else if (mask & (MAY_READ | MAY_EXEC))
+                iint->readcount--;
+        mutex_unlock(&iint->mutex);
+}
+
+/*
+ * ima_counts_get - increment file counts
  *
  * - for IPC shm and shmat file.
  * - for nfsd exported files.