Smack: Abstract use of file security blob

Don't use the file->f_security pointer directly. Provide a helper function that provides the security blob pointer. Signed-off-by: Casey Schaufler <[email protected]> Reviewed-by: Kees Cook <[email protected]> Signed-off-by: Kees Cook <[email protected]>
jangid · Jan 8, 2019 · f28952a · f28952a
1 parent bb6c6b0
commit f28952a
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/security/smack/smack.h b/security/smack/smack.h
@@ -362,6 +362,11 @@ static inline struct task_smack *smack_cred(const struct cred *cred)
 	return cred->security + smack_blob_sizes.lbs_cred;
 }
 
+static inline struct smack_known **smack_file(const struct file *file)
+{
+	return (struct smack_known **)&file->f_security;
+}
+
 /*
  * Is the directory transmuting?
  */

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
@@ -1489,9 +1489,9 @@ static void smack_inode_getsecid(struct inode *inode, u32 *secid)
  */
 static int smack_file_alloc_security(struct file *file)
 {
-	struct smack_known *skp = smk_of_current();
+	struct smack_known **blob = smack_file(file);
 
-	file->f_security = skp;
+	*blob = smk_of_current();
 	return 0;
 }
 
@@ -1731,7 +1731,9 @@ static int smack_mmap_file(struct file *file,
  */
 static void smack_file_set_fowner(struct file *file)
 {
-	file->f_security = smk_of_current();
+	struct smack_known **blob = smack_file(file);
+
+	*blob = smk_of_current();
 }
 
 /**
@@ -1748,6 +1750,7 @@ static void smack_file_set_fowner(struct file *file)
 static int smack_file_send_sigiotask(struct task_struct *tsk,
 				     struct fown_struct *fown, int signum)
 {
+	struct smack_known **blob;
 	struct smack_known *skp;
 	struct smack_known *tkp = smk_of_task(smack_cred(tsk->cred));
 	const struct cred *tcred;
@@ -1761,7 +1764,8 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
 	file = container_of(fown, struct file, f_owner);
 
 	/* we don't log here as rc can be overriden */
-	skp = file->f_security;
+	blob = smack_file(file);
+	skp = *blob;
 	rc = smk_access(skp, tkp, MAY_DELIVER, NULL);
 	rc = smk_bu_note("sigiotask", skp, tkp, MAY_DELIVER, rc);