[RFC 04/11] slim down securityfs

From: Arnd Bergmann
Date: Mon Feb 18 2008 - 23:12:55 EST


With the new simple_fs_type in place, securityfs practically
becomes a nop and we just need to leave code around to manage
its mount point.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Index: linux-2.6/security/inode.c
===================================================================
--- linux-2.6.orig/security/inode.c
+++ linux-2.6/security/inode.c
@@ -13,176 +13,14 @@
*/

/* #define DEBUG */
+
#include <linux/module.h>
-#include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/pagemap.h>
#include <linux/init.h>
-#include <linux/namei.h>
#include <linux/security.h>

#define SECURITYFS_MAGIC 0x73636673

-static struct vfsmount *mount;
-static int mount_count;
-
-/*
- * TODO:
- * I think I can get rid of these default_file_ops, but not quite sure...
- */
-static ssize_t default_read_file(struct file *file, char __user *buf,
- size_t count, loff_t *ppos)
-{
- return 0;
-}
-
-static ssize_t default_write_file(struct file *file, const char __user *buf,
- size_t count, loff_t *ppos)
-{
- return count;
-}
-
-static int default_open(struct inode *inode, struct file *file)
-{
- if (inode->i_private)
- file->private_data = inode->i_private;
-
- return 0;
-}
-
-static const struct file_operations default_file_ops = {
- .read = default_read_file,
- .write = default_write_file,
- .open = default_open,
-};
-
-static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
-{
- struct inode *inode = new_inode(sb);
-
- if (inode) {
- inode->i_mode = mode;
- inode->i_uid = 0;
- inode->i_gid = 0;
- inode->i_blocks = 0;
- inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
- switch (mode & S_IFMT) {
- default:
- init_special_inode(inode, mode, dev);
- break;
- case S_IFREG:
- inode->i_fop = &default_file_ops;
- break;
- case S_IFDIR:
- inode->i_op = &simple_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
-
- /* directory inodes start off with i_nlink == 2 (for "." entry) */
- inc_nlink(inode);
- break;
- }
- }
- return inode;
-}
-
-/* SMP-safe */
-static int mknod(struct inode *dir, struct dentry *dentry,
- int mode, dev_t dev)
-{
- struct inode *inode;
- int error = -EPERM;
-
- if (dentry->d_inode)
- return -EEXIST;
-
- inode = get_inode(dir->i_sb, mode, dev);
- if (inode) {
- d_instantiate(dentry, inode);
- dget(dentry);
- error = 0;
- }
- return error;
-}
-
-static int mkdir(struct inode *dir, struct dentry *dentry, int mode)
-{
- int res;
-
- mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
- res = mknod(dir, dentry, mode, 0);
- if (!res)
- inc_nlink(dir);
- return res;
-}
-
-static int create(struct inode *dir, struct dentry *dentry, int mode)
-{
- mode = (mode & S_IALLUGO) | S_IFREG;
- return mknod(dir, dentry, mode, 0);
-}
-
-static inline int positive(struct dentry *dentry)
-{
- return dentry->d_inode && !d_unhashed(dentry);
-}
-
-static int fill_super(struct super_block *sb, void *data, int silent)
-{
- static struct tree_descr files[] = {{""}};
-
- return simple_fill_super(sb, SECURITYFS_MAGIC, files);
-}
-
-static int get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name,
- void *data, struct vfsmount *mnt)
-{
- return get_sb_single(fs_type, flags, data, fill_super, mnt);
-}
-
-static struct file_system_type fs_type = {
- .owner = THIS_MODULE,
- .name = "securityfs",
- .get_sb = get_sb,
- .kill_sb = kill_litter_super,
-};
-
-static int create_by_name(const char *name, mode_t mode,
- struct dentry *parent,
- struct dentry **dentry)
-{
- int error = 0;
-
- *dentry = NULL;
-
- /* If the parent is not specified, we create it in the root.
- * We need the root dentry to do this, which is in the super
- * block. A pointer to that is in the struct vfsmount that we
- * have around.
- */
- if (!parent ) {
- if (mount && mount->mnt_sb) {
- parent = mount->mnt_sb->s_root;
- }
- }
- if (!parent) {
- pr_debug("securityfs: Ah! can not find a parent!\n");
- return -EFAULT;
- }
-
- mutex_lock(&parent->d_inode->i_mutex);
- *dentry = lookup_one_len(name, parent, strlen(name));
- if (!IS_ERR(dentry)) {
- if ((mode & S_IFMT) == S_IFDIR)
- error = mkdir(parent->d_inode, *dentry, mode);
- else
- error = create(parent->d_inode, *dentry, mode);
- } else
- error = PTR_ERR(dentry);
- mutex_unlock(&parent->d_inode->i_mutex);
-
- return error;
-}
+static struct dentry *securityfs_root;

/**
* securityfs_create_file - create a file in the securityfs filesystem
@@ -217,32 +55,12 @@ struct dentry *securityfs_create_file(co
struct dentry *parent, void *data,
const struct file_operations *fops)
{
- struct dentry *dentry = NULL;
- int error;
+ if (!parent)
+ parent = securityfs_root;

pr_debug("securityfs: creating file '%s'\n",name);

- error = simple_pin_fs(&fs_type, &mount, &mount_count);
- if (error) {
- dentry = ERR_PTR(error);
- goto exit;
- }
-
- error = create_by_name(name, mode, parent, &dentry);
- if (error) {
- dentry = ERR_PTR(error);
- simple_release_fs(&mount, &mount_count);
- goto exit;
- }
-
- if (dentry->d_inode) {
- if (fops)
- dentry->d_inode->i_fop = fops;
- if (data)
- dentry->d_inode->i_private = data;
- }
-exit:
- return dentry;
+ return simple_create_file(name, mode, parent, data, fops);
}
EXPORT_SYMBOL_GPL(securityfs_create_file);

@@ -291,31 +109,12 @@ EXPORT_SYMBOL_GPL(securityfs_create_dir)
*/
void securityfs_remove(struct dentry *dentry)
{
- struct dentry *parent;
-
- if (!dentry)
- return;
-
- parent = dentry->d_parent;
- if (!parent || !parent->d_inode)
- return;
-
- mutex_lock(&parent->d_inode->i_mutex);
- if (positive(dentry)) {
- if (dentry->d_inode) {
- if (S_ISDIR(dentry->d_inode->i_mode))
- simple_rmdir(parent->d_inode, dentry);
- else
- simple_unlink(parent->d_inode, dentry);
- dput(dentry);
- }
- }
- mutex_unlock(&parent->d_inode->i_mutex);
- simple_release_fs(&mount, &mount_count);
+ return simple_remove(dentry);
}
EXPORT_SYMBOL_GPL(securityfs_remove);

static struct kobject *security_kobj;
+static DEFINE_SIMPLE_FS(fs_type, "securityfs", NULL, SECURITYFS_MAGIC);

static int __init securityfs_init(void)
{
@@ -325,12 +124,14 @@ static int __init securityfs_init(void)
if (!security_kobj)
return -EINVAL;

- retval = register_filesystem(&fs_type);
- if (retval)
+ retval = 0;
+ securityfs_root = simple_register_filesystem(&fs_type);
+ if (IS_ERR(securityfs_root)) {
kobject_put(security_kobj);
+ retval = PTR_ERR(securityfs_root);
+ }
return retval;
}

core_initcall(securityfs_init);
MODULE_LICENSE("GPL");
-

--

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