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>

2 files changed, 18 insertions, 5 deletions

diff --git a/include/linux/security.h b/include/linux/security.h
index 8ce59ef3e5af..6a20c7025495 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -36,6 +36,7 @@
 #include <linux/key.h>
 #include <linux/xfrm.h>
 #include <linux/slab.h>
+#include <linux/xattr.h>
 #include <net/flow.h>
 
 /* Maximum number of letters for an LSM name string */
@@ -147,6 +148,10 @@ extern int mmap_min_addr_handler(struct ctl_table *table, int write,
 				 void __user *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
+/* security_inode_init_security callback function to write xattrs */
+typedef int (*initxattrs) (struct inode *inode,
+			   const struct xattr *xattr_array, void *fs_data);
+
 #ifdef CONFIG_SECURITY
 
 struct security_mnt_opts {
@@ -1704,8 +1709,11 @@ int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts);
 int security_inode_alloc(struct inode *inode);
 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,
+				 initxattrs initxattrs, void *fs_data);
+int security_old_inode_init_security(struct inode *inode, struct inode *dir,
+				     const struct qstr *qstr, char **name,
+				     void **value, size_t *len);
 int security_inode_create(struct inode *dir, struct dentry *dentry, int mode);
 int security_inode_link(struct dentry *old_dentry, struct inode *dir,
 			 struct dentry *new_dentry);
@@ -2035,9 +2043,8 @@ static inline void security_inode_free(struct inode *inode)
 static inline int security_inode_init_security(struct inode *inode,
 						struct inode *dir,
 						const struct qstr *qstr,
-						char **name,
-						void **value,
-						size_t *len)
+						initxattrs initxattrs,
+						void *fs_data)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index aed54c50aa66..7a378662ddff 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -67,6 +67,12 @@ struct xattr_handler {
 		   size_t size, int flags, int handler_flags);
 };
 
+struct xattr {
+	char *name;
+	void *value;
+	size_t value_len;
+};
+
 ssize_t xattr_getsecurity(struct inode *, const char *, void *, size_t);
 ssize_t vfs_getxattr(struct dentry *, const char *, void *, size_t);
 ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);