mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-04 09:59:32 +00:00
![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 021110 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 84 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190524100844.756442981@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
295 lines
6.5 KiB
C
295 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/* -*- mode: c; c-basic-offset: 8; -*-
|
|
* vim: noexpandtab sw=8 ts=8 sts=0:
|
|
*
|
|
* symlink.c - operations for configfs symlinks.
|
|
*
|
|
* Based on sysfs:
|
|
* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
|
|
*
|
|
* configfs Copyright (C) 2005 Oracle. All rights reserved.
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/module.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/slab.h>
|
|
|
|
#include <linux/configfs.h>
|
|
#include "configfs_internal.h"
|
|
|
|
/* Protects attachments of new symlinks */
|
|
DEFINE_MUTEX(configfs_symlink_mutex);
|
|
|
|
static int item_depth(struct config_item * item)
|
|
{
|
|
struct config_item * p = item;
|
|
int depth = 0;
|
|
do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p));
|
|
return depth;
|
|
}
|
|
|
|
static int item_path_length(struct config_item * item)
|
|
{
|
|
struct config_item * p = item;
|
|
int length = 1;
|
|
do {
|
|
length += strlen(config_item_name(p)) + 1;
|
|
p = p->ci_parent;
|
|
} while (p && !configfs_is_root(p));
|
|
return length;
|
|
}
|
|
|
|
static void fill_item_path(struct config_item * item, char * buffer, int length)
|
|
{
|
|
struct config_item * p;
|
|
|
|
--length;
|
|
for (p = item; p && !configfs_is_root(p); p = p->ci_parent) {
|
|
int cur = strlen(config_item_name(p));
|
|
|
|
/* back up enough to print this bus id with '/' */
|
|
length -= cur;
|
|
memcpy(buffer + length, config_item_name(p), cur);
|
|
*(buffer + --length) = '/';
|
|
}
|
|
}
|
|
|
|
static int create_link(struct config_item *parent_item,
|
|
struct config_item *item,
|
|
struct dentry *dentry)
|
|
{
|
|
struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
|
|
struct configfs_symlink *sl;
|
|
int ret;
|
|
|
|
ret = -ENOENT;
|
|
if (!configfs_dirent_is_ready(target_sd))
|
|
goto out;
|
|
ret = -ENOMEM;
|
|
sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
|
|
if (sl) {
|
|
spin_lock(&configfs_dirent_lock);
|
|
if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
|
|
spin_unlock(&configfs_dirent_lock);
|
|
kfree(sl);
|
|
return -ENOENT;
|
|
}
|
|
sl->sl_target = config_item_get(item);
|
|
list_add(&sl->sl_list, &target_sd->s_links);
|
|
spin_unlock(&configfs_dirent_lock);
|
|
ret = configfs_create_link(sl, parent_item->ci_dentry,
|
|
dentry);
|
|
if (ret) {
|
|
spin_lock(&configfs_dirent_lock);
|
|
list_del_init(&sl->sl_list);
|
|
spin_unlock(&configfs_dirent_lock);
|
|
config_item_put(item);
|
|
kfree(sl);
|
|
}
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
|
|
static int get_target(const char *symname, struct path *path,
|
|
struct config_item **target, struct super_block *sb)
|
|
{
|
|
int ret;
|
|
|
|
ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path);
|
|
if (!ret) {
|
|
if (path->dentry->d_sb == sb) {
|
|
*target = configfs_get_config_item(path->dentry);
|
|
if (!*target) {
|
|
ret = -ENOENT;
|
|
path_put(path);
|
|
}
|
|
} else {
|
|
ret = -EPERM;
|
|
path_put(path);
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
|
|
int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
|
|
{
|
|
int ret;
|
|
struct path path;
|
|
struct configfs_dirent *sd;
|
|
struct config_item *parent_item;
|
|
struct config_item *target_item = NULL;
|
|
const struct config_item_type *type;
|
|
|
|
sd = dentry->d_parent->d_fsdata;
|
|
/*
|
|
* Fake invisibility if dir belongs to a group/default groups hierarchy
|
|
* being attached
|
|
*/
|
|
ret = -ENOENT;
|
|
if (!configfs_dirent_is_ready(sd))
|
|
goto out;
|
|
|
|
parent_item = configfs_get_config_item(dentry->d_parent);
|
|
type = parent_item->ci_type;
|
|
|
|
ret = -EPERM;
|
|
if (!type || !type->ct_item_ops ||
|
|
!type->ct_item_ops->allow_link)
|
|
goto out_put;
|
|
|
|
ret = get_target(symname, &path, &target_item, dentry->d_sb);
|
|
if (ret)
|
|
goto out_put;
|
|
|
|
ret = type->ct_item_ops->allow_link(parent_item, target_item);
|
|
if (!ret) {
|
|
mutex_lock(&configfs_symlink_mutex);
|
|
ret = create_link(parent_item, target_item, dentry);
|
|
mutex_unlock(&configfs_symlink_mutex);
|
|
if (ret && type->ct_item_ops->drop_link)
|
|
type->ct_item_ops->drop_link(parent_item,
|
|
target_item);
|
|
}
|
|
|
|
config_item_put(target_item);
|
|
path_put(&path);
|
|
|
|
out_put:
|
|
config_item_put(parent_item);
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
int configfs_unlink(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
struct configfs_dirent *sd = dentry->d_fsdata;
|
|
struct configfs_symlink *sl;
|
|
struct config_item *parent_item;
|
|
const struct config_item_type *type;
|
|
int ret;
|
|
|
|
ret = -EPERM; /* What lack-of-symlink returns */
|
|
if (!(sd->s_type & CONFIGFS_ITEM_LINK))
|
|
goto out;
|
|
|
|
sl = sd->s_element;
|
|
|
|
parent_item = configfs_get_config_item(dentry->d_parent);
|
|
type = parent_item->ci_type;
|
|
|
|
spin_lock(&configfs_dirent_lock);
|
|
list_del_init(&sd->s_sibling);
|
|
spin_unlock(&configfs_dirent_lock);
|
|
configfs_drop_dentry(sd, dentry->d_parent);
|
|
dput(dentry);
|
|
configfs_put(sd);
|
|
|
|
/*
|
|
* drop_link() must be called before
|
|
* list_del_init(&sl->sl_list), so that the order of
|
|
* drop_link(this, target) and drop_item(target) is preserved.
|
|
*/
|
|
if (type && type->ct_item_ops &&
|
|
type->ct_item_ops->drop_link)
|
|
type->ct_item_ops->drop_link(parent_item,
|
|
sl->sl_target);
|
|
|
|
spin_lock(&configfs_dirent_lock);
|
|
list_del_init(&sl->sl_list);
|
|
spin_unlock(&configfs_dirent_lock);
|
|
|
|
/* Put reference from create_link() */
|
|
config_item_put(sl->sl_target);
|
|
kfree(sl);
|
|
|
|
config_item_put(parent_item);
|
|
|
|
ret = 0;
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static int configfs_get_target_path(struct config_item * item, struct config_item * target,
|
|
char *path)
|
|
{
|
|
char * s;
|
|
int depth, size;
|
|
|
|
depth = item_depth(item);
|
|
size = item_path_length(target) + depth * 3 - 1;
|
|
if (size > PATH_MAX)
|
|
return -ENAMETOOLONG;
|
|
|
|
pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
|
|
|
|
for (s = path; depth--; s += 3)
|
|
strcpy(s,"../");
|
|
|
|
fill_item_path(target, path, size);
|
|
pr_debug("%s: path = '%s'\n", __func__, path);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int configfs_getlink(struct dentry *dentry, char * path)
|
|
{
|
|
struct config_item *item, *target_item;
|
|
int error = 0;
|
|
|
|
item = configfs_get_config_item(dentry->d_parent);
|
|
if (!item)
|
|
return -EINVAL;
|
|
|
|
target_item = configfs_get_config_item(dentry);
|
|
if (!target_item) {
|
|
config_item_put(item);
|
|
return -EINVAL;
|
|
}
|
|
|
|
down_read(&configfs_rename_sem);
|
|
error = configfs_get_target_path(item, target_item, path);
|
|
up_read(&configfs_rename_sem);
|
|
|
|
config_item_put(item);
|
|
config_item_put(target_item);
|
|
return error;
|
|
|
|
}
|
|
|
|
static const char *configfs_get_link(struct dentry *dentry,
|
|
struct inode *inode,
|
|
struct delayed_call *done)
|
|
{
|
|
char *body;
|
|
int error;
|
|
|
|
if (!dentry)
|
|
return ERR_PTR(-ECHILD);
|
|
|
|
body = kzalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!body)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
error = configfs_getlink(dentry, body);
|
|
if (!error) {
|
|
set_delayed_call(done, kfree_link, body);
|
|
return body;
|
|
}
|
|
|
|
kfree(body);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
const struct inode_operations configfs_symlink_inode_operations = {
|
|
.get_link = configfs_get_link,
|
|
.setattr = configfs_setattr,
|
|
};
|
|
|