security: Fix security_old_inode_init_security() when CONFIG_SECURITY is not set

Commit 1e39f384 ("evm: fix build problems") makes the stub version
of security_old_inode_init_security() return 0 when CONFIG_SECURITY is
not set.

But that makes callers such as reiserfs_security_init() assume that
security_old_inode_init_security() has set name, value, and len
arguments properly - but security_old_inode_init_security() left them
uninitialized which then results in interesting failures.

Revert security_old_inode_init_security() to the old behavior of
returning EOPNOTSUPP since both callers (reiserfs and ocfs2) handle this
just fine.

[ Also fixed the S_PRIVATE(inode) case of the actual non-stub
  security_old_inode_init_security() function to return EOPNOTSUPP
  for the same reason, as pointed out by Mimi Zohar.

  It got incorrectly changed to match the new function in commit
  fb88c2b6: "evm: fix security/security_old_init_security return
  code".   - Linus ]
Reported-by: Jorge Bastos <mysql.jorge@decimal.pt>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/security.h

@@ -2056,7 +2056,7 @@ static inline int security_old_inode_init_security(struct inode *inode,
 						   char **name, void **value,
 						   size_t *len)
 {
-	return 0;
+	return -EOPNOTSUPP;
 }
 
 static inline int security_inode_create(struct inode *dir,

security/security.c

@@ -381,7 +381,7 @@ int security_old_inode_init_security(struct inode *inode, struct inode *dir,
 				     void **value, size_t *len)
 {
 	if (unlikely(IS_PRIVATE(inode)))
-		return 0;
+		return -EOPNOTSUPP;
 	return security_ops->inode_init_security(inode, dir, qstr, name, value,
 						 len);
 }