security: new security_inode_init_security API adds function callback

This patch changes the security_inode_init_security API by adding a
filesystem specific callback to write security extended attributes.
This change is in preparation for supporting the initialization of
multiple LSM xattrs and the EVM xattr.  Initially the callback function
walks an array of xattrs, writing each xattr separately, but could be
optimized to write multiple xattrs at once.

For existing security_inode_init_security() calls, which have not yet
been converted to use the new callback function, such as those in
reiserfs and ocfs2, this patch defines security_old_inode_init_security().

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

1 files changed, 36 insertions, 3 deletions

diff --git a/security/security.c b/security/security.c
index 4ba6d4cc061..3464d58a576 100644
--- a/security/security.c
+++ b/security/security.c
@@ -18,6 +18,8 @@
 #include <linux/security.h>
 #include <linux/ima.h>
 
+#define MAX_LSM_XATTR   1
+
 /* Boot-time LSM user choice */
 static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
         CONFIG_DEFAULT_SECURITY;
@@ -339,15 +341,46 @@ void security_inode_free(struct inode *inode)
 }
 
 int security_inode_init_security(struct inode *inode, struct inode *dir,
-                                 const struct qstr *qstr, char **name,
-                                 void **value, size_t *len)
+                                 const struct qstr *qstr,
+                                 const initxattrs initxattrs, void *fs_data)
+{
+        struct xattr new_xattrs[MAX_LSM_XATTR + 1];
+        struct xattr *lsm_xattr;
+        int ret;
+
+        if (unlikely(IS_PRIVATE(inode)))
+                return -EOPNOTSUPP;
+
+        memset(new_xattrs, 0, sizeof new_xattrs);
+        if (!initxattrs)
+                return security_ops->inode_init_security(inode, dir, qstr,
+                                                         NULL, NULL, NULL);
+        lsm_xattr = new_xattrs;
+        ret = security_ops->inode_init_security(inode, dir, qstr,
+                                                &lsm_xattr->name,
+                                                &lsm_xattr->value,
+                                                &lsm_xattr->value_len);
+        if (ret)
+                goto out;
+        ret = initxattrs(inode, new_xattrs, fs_data);
+out:
+        kfree(lsm_xattr->name);
+        kfree(lsm_xattr->value);
+
+        return (ret == -EOPNOTSUPP) ? 0 : ret;
+}
+EXPORT_SYMBOL(security_inode_init_security);
+
+int security_old_inode_init_security(struct inode *inode, struct inode *dir,
+                                     const struct qstr *qstr, char **name,
+                                     void **value, size_t *len)
 {
         if (unlikely(IS_PRIVATE(inode)))
                 return -EOPNOTSUPP;
         return security_ops->inode_init_security(inode, dir, qstr, name, value,
                                                  len);
 }
-EXPORT_SYMBOL(security_inode_init_security);
+EXPORT_SYMBOL(security_old_inode_init_security);
 
 #ifdef CONFIG_SECURITY_PATH
 int security_path_mknod(struct path *dir, struct dentry *dentry, int mode,