configfs: Add permission and ownership to configfs objects.

configfs always made item and attribute ownership root.root and
permissions based on a umask of 022.  Add ->setattr() to allow
chown(2)/chmod(2), and persist the changes for the lifetime of the
items and attributes.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

Documentation/filesystems/configfs/configfs_example.c

@@ -320,6 +320,7 @@ static struct config_item_type simple_children_type = {
 	.ct_item_ops	= &simple_children_item_ops,
 	.ct_group_ops	= &simple_children_group_ops,
 	.ct_attrs	= simple_children_attrs,
+	.ct_owner	= THIS_MODULE,
 };
 
 static struct configfs_subsystem simple_children_subsys = {
@@ -403,6 +404,7 @@ static struct config_item_type group_children_type = {
 	.ct_item_ops	= &group_children_item_ops,
 	.ct_group_ops	= &group_children_group_ops,
 	.ct_attrs	= group_children_attrs,
+	.ct_owner	= THIS_MODULE,
 };
 
 static struct configfs_subsystem group_children_subsys = {

fs/configfs/configfs_internal.h

@@ -36,6 +36,7 @@ struct configfs_dirent {
 	int			s_type;
 	umode_t			s_mode;
 	struct dentry		* s_dentry;
+	struct iattr		* s_iattr;
 };
 
 #define CONFIGFS_ROOT		0x0001
@@ -48,10 +49,11 @@ struct configfs_dirent {
 #define CONFIGFS_NOT_PINNED	(CONFIGFS_ITEM_ATTR)
 
 extern struct vfsmount * configfs_mount;
+extern kmem_cache_t *configfs_dir_cachep;
 
 extern int configfs_is_root(struct config_item *item);
 
-extern struct inode * configfs_new_inode(mode_t mode);
+extern struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent *);
 extern int configfs_create(struct dentry *, int mode, int (*init)(struct inode *));
 
 extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
@@ -63,6 +65,7 @@ extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
 
 extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
 extern void configfs_drop_dentry(struct configfs_dirent *sd, struct dentry *parent);
+extern int configfs_setattr(struct dentry *dentry, struct iattr *iattr);
 
 extern int configfs_pin_fs(void);
 extern void configfs_release_fs(void);
@@ -120,8 +123,10 @@ static inline struct config_item *configfs_get_config_item(struct dentry *dentry
 
 static inline void release_configfs_dirent(struct configfs_dirent * sd)
 {
-	if (!(sd->s_type & CONFIGFS_ROOT))
-		kfree(sd);
+	if (!(sd->s_type & CONFIGFS_ROOT)) {
+		kfree(sd->s_iattr);
+		kmem_cache_free(configfs_dir_cachep, sd);
+	}
 }
 
 static inline struct configfs_dirent * configfs_get(struct configfs_dirent * sd)

fs/configfs/dir.c

@@ -72,7 +72,7 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * pare
 {
 	struct configfs_dirent * sd;
 
-	sd = kmalloc(sizeof(*sd), GFP_KERNEL);
+	sd = kmem_cache_alloc(configfs_dir_cachep, GFP_KERNEL);
 	if (!sd)
 		return NULL;
 
@@ -136,13 +136,19 @@ static int create_dir(struct config_item * k, struct dentry * p,
 	int error;
 	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 
-	error = configfs_create(d, mode, init_dir);
+	error = configfs_make_dirent(p->d_fsdata, d, k, mode,
+				     CONFIGFS_DIR);
 	if (!error) {
-		error = configfs_make_dirent(p->d_fsdata, d, k, mode,
-					   CONFIGFS_DIR);
+		error = configfs_create(d, mode, init_dir);
 		if (!error) {
 			p->d_inode->i_nlink++;
 			(d)->d_op = &configfs_dentry_ops;
+		} else {
+			struct configfs_dirent *sd = d->d_fsdata;
+			if (sd) {
+				list_del_init(&sd->s_sibling);
+				configfs_put(sd);
+			}
 		}
 	}
 	return error;
@@ -182,12 +188,19 @@ int configfs_create_link(struct configfs_symlink *sl,
 	int err = 0;
 	umode_t mode = S_IFLNK | S_IRWXUGO;
 
-	err = configfs_create(dentry, mode, init_symlink);
+	err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
+				   CONFIGFS_ITEM_LINK);
 	if (!err) {
-		err = configfs_make_dirent(parent->d_fsdata, dentry, sl,
-					 mode, CONFIGFS_ITEM_LINK);
+		err = configfs_create(dentry, mode, init_symlink);
 		if (!err)
 			dentry->d_op = &configfs_dentry_ops;
+		else {
+			struct configfs_dirent *sd = dentry->d_fsdata;
+			if (sd) {
+				list_del_init(&sd->s_sibling);
+				configfs_put(sd);
+			}
+		}
 	}
 	return err;
 }
@@ -241,13 +254,15 @@ static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * den
 	struct configfs_attribute * attr = sd->s_element;
 	int error;
 
+	dentry->d_fsdata = configfs_get(sd);
+	sd->s_dentry = dentry;
 	error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
-	if (error)
+	if (error) {
+		configfs_put(sd);
 		return error;
+	}
 
 	dentry->d_op = &configfs_dentry_ops;
-	dentry->d_fsdata = configfs_get(sd);
-	sd->s_dentry = dentry;
 	d_rehash(dentry);
 
 	return 0;
@@ -839,6 +854,7 @@ struct inode_operations configfs_dir_inode_operations = {
 	.symlink	= configfs_symlink,
 	.unlink		= configfs_unlink,
 	.lookup		= configfs_lookup,
+	.setattr	= configfs_setattr,
 };
 
 #if 0

fs/configfs/file.c

@@ -26,7 +26,6 @@
 
 #include <linux/fs.h>
 #include <linux/module.h>
-#include <linux/dnotify.h>
 #include <linux/slab.h>
 #include <asm/uaccess.h>
 #include <asm/semaphore.h>
@@ -150,7 +149,7 @@ out:
 /**
  *	fill_write_buffer - copy buffer from userspace.
  *	@buffer:	data buffer for file.
- *	@userbuf:	data from user.
+ *	@buf:		data from user.
  *	@count:		number of bytes in @userbuf.
  *
  *	Allocate @buffer->page if it hasn't been already, then
@@ -177,8 +176,9 @@ fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size
 
 /**
  *	flush_write_buffer - push buffer to config_item.
- *	@file:		file pointer.
+ *	@dentry:	dentry to the attribute
  *	@buffer:	data buffer for file.
+ *	@count:		number of bytes
  *
  *	Get the correct pointers for the config_item and the attribute we're
  *	dealing with, then call the store() method for the attribute,
@@ -217,15 +217,16 @@ static ssize_t
 configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 {
 	struct configfs_buffer * buffer = file->private_data;
+	ssize_t len;
 
 	down(&buffer->sem);
-	count = fill_write_buffer(buffer,buf,count);
-	if (count > 0)
-		count = flush_write_buffer(file->f_dentry,buffer,count);
-	if (count > 0)
-		*ppos += count;
+	len = fill_write_buffer(buffer, buf, count);
+	if (len > 0)
+		len = flush_write_buffer(file->f_dentry, buffer, count);
+	if (len > 0)
+		*ppos += len;
 	up(&buffer->sem);
-	return count;
+	return len;
 }
 
 static int check_perm(struct inode * inode, struct file * file)

fs/configfs/inode.c

@@ -31,6 +31,7 @@
 #include <linux/pagemap.h>
 #include <linux/namei.h>
 #include <linux/backing-dev.h>
+#include <linux/capability.h>
 
 #include <linux/configfs.h>
 #include "configfs_internal.h"
@@ -48,18 +49,107 @@ static struct backing_dev_info configfs_backing_dev_info = {
 	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
 };
 
-struct inode * configfs_new_inode(mode_t mode)
+static struct inode_operations configfs_inode_operations ={
+	.setattr	= configfs_setattr,
+};
+
+int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
+{
+	struct inode * inode = dentry->d_inode;
+	struct configfs_dirent * sd = dentry->d_fsdata;
+	struct iattr * sd_iattr;
+	unsigned int ia_valid = iattr->ia_valid;
+	int error;
+
+	if (!sd)
+		return -EINVAL;
+
+	sd_iattr = sd->s_iattr;
+
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		return error;
+
+	error = inode_setattr(inode, iattr);
+	if (error)
+		return error;
+
+	if (!sd_iattr) {
+		/* setting attributes for the first time, allocate now */
+		sd_iattr = kmalloc(sizeof(struct iattr), GFP_KERNEL);
+		if (!sd_iattr)
+			return -ENOMEM;
+		/* assign default attributes */
+		memset(sd_iattr, 0, sizeof(struct iattr));
+		sd_iattr->ia_mode = sd->s_mode;
+		sd_iattr->ia_uid = 0;
+		sd_iattr->ia_gid = 0;
+		sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
+		sd->s_iattr = sd_iattr;
+	}
+
+	/* attributes were changed atleast once in past */
+
+	if (ia_valid & ATTR_UID)
+		sd_iattr->ia_uid = iattr->ia_uid;
+	if (ia_valid & ATTR_GID)
+		sd_iattr->ia_gid = iattr->ia_gid;
+	if (ia_valid & ATTR_ATIME)
+		sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_MTIME)
+		sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_CTIME)
+		sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = iattr->ia_mode;
+
+		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+			mode &= ~S_ISGID;
+		sd_iattr->ia_mode = sd->s_mode = mode;
+	}
+
+	return error;
+}
+
+static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
+{
+	inode->i_mode = mode;
+	inode->i_uid = 0;
+	inode->i_gid = 0;
+	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+
+static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
+{
+	inode->i_mode = iattr->ia_mode;
+	inode->i_uid = iattr->ia_uid;
+	inode->i_gid = iattr->ia_gid;
+	inode->i_atime = iattr->ia_atime;
+	inode->i_mtime = iattr->ia_mtime;
+	inode->i_ctime = iattr->ia_ctime;
+}
+
+struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
 {
 	struct inode * inode = new_inode(configfs_sb);
 	if (inode) {
-		inode->i_mode = mode;
-		inode->i_uid = 0;
-		inode->i_gid = 0;
 		inode->i_blksize = PAGE_CACHE_SIZE;
 		inode->i_blocks = 0;
-		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inode->i_mapping->a_ops = &configfs_aops;
 		inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
+		inode->i_op = &configfs_inode_operations;
+
+		if (sd->s_iattr) {
+			/* sysfs_dirent has non-default attributes
+			 * get them for the new inode from persistent copy
+			 * in sysfs_dirent
+			 */
+			set_inode_attr(inode, sd->s_iattr);
+		} else
+			set_default_inode_attr(inode, mode);
 	}
 	return inode;
 }
@@ -70,7 +160,8 @@ int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *
 	struct inode * inode = NULL;
 	if (dentry) {
 		if (!dentry->d_inode) {
-			if ((inode = configfs_new_inode(mode))) {
+			struct configfs_dirent *sd = dentry->d_fsdata;
+			if ((inode = configfs_new_inode(mode, sd))) {
 				if (dentry->d_parent && dentry->d_parent->d_inode) {
 					struct inode *p_inode = dentry->d_parent->d_inode;
 					p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
@@ -103,7 +194,7 @@ int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *
  */
 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 {
-	struct attribute * attr;
+	struct configfs_attribute *attr;
 
 	if (!sd || !sd->s_element)
 		BUG();
@@ -114,7 +205,7 @@ const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 
 	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 		attr = sd->s_element;
-		return attr->name;
+		return attr->ca_name;
 	}
 	return NULL;
 }
@@ -130,13 +221,17 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 
 	if (dentry) {
 		spin_lock(&dcache_lock);
+		spin_lock(&dentry->d_lock);
 		if (!(d_unhashed(dentry) && dentry->d_inode)) {
 			dget_locked(dentry);
 			__d_drop(dentry);
+			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dcache_lock);
 			simple_unlink(parent->d_inode, dentry);
-		} else
+		} else {
+			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dcache_lock);
+		}
 	}
 }
 
@@ -145,6 +240,10 @@ void configfs_hash_and_remove(struct dentry * dir, const char * name)
 	struct configfs_dirent * sd;
 	struct configfs_dirent * parent_sd = dir->d_fsdata;
 
+	if (dir->d_inode == NULL)
+		/* no inode means this hasn't been made visible yet */
+		return;
+
 	mutex_lock(&dir->d_inode->i_mutex);
 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 		if (!sd->s_element)

fs/configfs/mount.c

@@ -38,6 +38,7 @@
 
 struct vfsmount * configfs_mount = NULL;
 struct super_block * configfs_sb = NULL;
+kmem_cache_t *configfs_dir_cachep;
 static int configfs_mnt_count = 0;
 
 static struct super_operations configfs_ops = {
@@ -62,6 +63,7 @@ static struct configfs_dirent configfs_root = {
 	.s_children	= LIST_HEAD_INIT(configfs_root.s_children),
 	.s_element	= &configfs_root_group.cg_item,
 	.s_type		= CONFIGFS_ROOT,
+	.s_iattr	= NULL,
 };
 
 static int configfs_fill_super(struct super_block *sb, void *data, int silent)
@@ -73,9 +75,11 @@ static int configfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 	sb->s_magic = CONFIGFS_MAGIC;
 	sb->s_op = &configfs_ops;
+	sb->s_time_gran = 1;
 	configfs_sb = sb;
 
-	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO);
+	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
+				   &configfs_root);
 	if (inode) {
 		inode->i_op = &configfs_dir_inode_operations;
 		inode->i_fop = &configfs_dir_operations;
@@ -128,19 +132,31 @@ static decl_subsys(config, NULL, NULL);
 
 static int __init configfs_init(void)
 {
-	int err;
+	int err = -ENOMEM;
+
+	configfs_dir_cachep = kmem_cache_create("configfs_dir_cache",
+						sizeof(struct configfs_dirent),
+						0, 0, NULL, NULL);
+	if (!configfs_dir_cachep)
+		goto out;
 
 	kset_set_kset_s(&config_subsys, kernel_subsys);
 	err = subsystem_register(&config_subsys);
-	if (err)
-		return err;
+	if (err) {
+		kmem_cache_destroy(configfs_dir_cachep);
+		configfs_dir_cachep = NULL;
+		goto out;
+	}
 
 	err = register_filesystem(&configfs_fs_type);
 	if (err) {
 		printk(KERN_ERR "configfs: Unable to register filesystem!\n");
 		subsystem_unregister(&config_subsys);
+		kmem_cache_destroy(configfs_dir_cachep);
+		configfs_dir_cachep = NULL;
 	}
 
+out:
 	return err;
 }
 
@@ -148,11 +164,13 @@ static void __exit configfs_exit(void)
 {
 	unregister_filesystem(&configfs_fs_type);
 	subsystem_unregister(&config_subsys);
+	kmem_cache_destroy(configfs_dir_cachep);
+	configfs_dir_cachep = NULL;
 }
 
 MODULE_AUTHOR("Oracle");
 MODULE_LICENSE("GPL");
-MODULE_VERSION("0.0.1");
+MODULE_VERSION("0.0.2");
 MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
 
 module_init(configfs_init);

fs/configfs/symlink.c

@@ -277,5 +277,6 @@ struct inode_operations configfs_symlink_inode_operations = {
 	.follow_link = configfs_follow_link,
 	.readlink = generic_readlink,
 	.put_link = configfs_put_link,
+	.setattr = configfs_setattr,
 };
 

include/linux/configfs.h

@@ -126,7 +126,7 @@ extern struct config_item *config_group_find_obj(struct config_group *, const ch
 
 
 struct configfs_attribute {
-	char			*ca_name;
+	const char		*ca_name;
 	struct module 		*ca_owner;
 	mode_t			ca_mode;
 };