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>

8 files changed, 179 insertions, 37 deletions

diff --git a/Documentation/filesystems/configfs/configfs_example.c b/Documentation/filesystems/configfs/configfs_example.c
index f3c6e4946f98..3d4713a6c207 100644
--- a/Documentation/filesystems/configfs/configfs_example.c
+++ b/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 = {
diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index 8899d9c5f6bf..f70e46951b37 100644
--- a/fs/configfs/configfs_internal.h
+++ b/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)
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index b668ec61527e..ca60e3abef45 100644
--- a/fs/configfs/dir.c
+++ b/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
diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index c26cd61f13af..3921920d8716 100644
--- a/fs/configfs/file.c
+++ b/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)
diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index 6577c588de9d..737842f2764b 100644
--- a/fs/configfs/inode.c
+++ b/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)
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 1a2f6f6a4d91..f920d30478e5 100644
--- a/fs/configfs/mount.c
+++ b/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);
diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
index 50f5840521a9..99137026b409 100644
--- a/fs/configfs/symlink.c
+++ b/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,
 };
 
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index acffb8c9073a..a7f015027535 100644
--- a/include/linux/configfs.h
+++ b/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;
 };