1 files changed, 42 insertions, 4 deletions

diff --git a/security/inode.c b/security/inode.c
index 43382ef8896e..ab8d6a2acadb 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -22,6 +22,8 @@
 #include <linux/lsm_hooks.h>
 #include <linux/magic.h>
 
+#include "lsm.h"
+
 static struct vfsmount *mount;
 static int mount_count;
 
@@ -315,12 +317,49 @@ void securityfs_remove(struct dentry *dentry)
 EXPORT_SYMBOL_GPL(securityfs_remove);
 
 #ifdef CONFIG_SECURITY
+#include <linux/spinlock.h>
+
 static struct dentry *lsm_dentry;
+
 static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
 			loff_t *ppos)
 {
-	return simple_read_from_buffer(buf, count, ppos, lsm_names,
-		strlen(lsm_names));
+	int i;
+	static char *str;
+	static size_t len;
+	static DEFINE_SPINLOCK(lock);
+
+	/* NOTE: we never free or modify the string once it is set */
+
+	if (unlikely(!str || !len)) {
+		char *str_tmp;
+		size_t len_tmp = 0;
+
+		for (i = 0; i < lsm_active_cnt; i++)
+			/* the '+ 1' accounts for either a comma or a NUL */
+			len_tmp += strlen(lsm_idlist[i]->name) + 1;
+
+		str_tmp = kmalloc(len_tmp, GFP_KERNEL);
+		if (!str_tmp)
+			return -ENOMEM;
+		str_tmp[0] = '\0';
+
+		for (i = 0; i < lsm_active_cnt; i++) {
+			if (i > 0)
+				strcat(str_tmp, ",");
+			strcat(str_tmp, lsm_idlist[i]->name);
+		}
+
+		spin_lock(&lock);
+		if (!str) {
+			str = str_tmp;
+			len = len_tmp - 1;
+		} else
+			kfree(str_tmp);
+		spin_unlock(&lock);
+	}
+
+	return simple_read_from_buffer(buf, count, ppos, str, len);
 }
 
 static const struct file_operations lsm_ops = {
@@ -329,7 +368,7 @@ static const struct file_operations lsm_ops = {
 };
 #endif
 
-static int __init securityfs_init(void)
+int __init securityfs_init(void)
 {
 	int retval;
 
@@ -348,4 +387,3 @@ static int __init securityfs_init(void)
 #endif
 	return 0;
 }
-core_initcall(securityfs_init);