mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
![Honggang Li](/assets/img/avatar_default.png)
When create symbolic link, create_link should calculate the depth
of the parent item. However, both the first and second parameters
of configfs_get_target_path had been set to the target. Broken
symbolic link created.
$ targetcli ls /
o- / ............................................................. [...]
o- backstores .................................................. [...]
| o- block ...................................... [Storage Objects: 0]
| o- fileio ..................................... [Storage Objects: 2]
| | o- vdev0 .......... [/dev/ramdisk1 (16.0MiB) write-thru activated]
| | | o- alua ....................................... [ALUA Groups: 1]
| | | o- default_tg_pt_gp ........... [ALUA state: Active/optimized]
| | o- vdev1 .......... [/dev/ramdisk2 (16.0MiB) write-thru activated]
| | o- alua ....................................... [ALUA Groups: 1]
| | o- default_tg_pt_gp ........... [ALUA state: Active/optimized]
| o- pscsi ...................................... [Storage Objects: 0]
| o- ramdisk .................................... [Storage Objects: 0]
o- iscsi ................................................ [Targets: 0]
o- loopback ............................................. [Targets: 0]
o- srpt ................................................. [Targets: 2]
| o- ib.e89a8f91cb3200000000000000000000 ............... [no-gen-acls]
| | o- acls ................................................ [ACLs: 2]
| | | o- ib.e89a8f91cb3200000000000000000000 ........ [Mapped LUNs: 2]
| | | | o- mapped_lun0 ............................. [BROKEN LUN LINK]
| | | | o- mapped_lun1 ............................. [BROKEN LUN LINK]
| | | o- ib.e89a8f91cb3300000000000000000000 ........ [Mapped LUNs: 2]
| | | o- mapped_lun0 ............................. [BROKEN LUN LINK]
| | | o- mapped_lun1 ............................. [BROKEN LUN LINK]
| | o- luns ................................................ [LUNs: 2]
| | o- lun0 ...... [fileio/vdev0 (/dev/ramdisk1) (default_tg_pt_gp)]
| | o- lun1 ...... [fileio/vdev1 (/dev/ramdisk2) (default_tg_pt_gp)]
| o- ib.e89a8f91cb3300000000000000000000 ............... [no-gen-acls]
| o- acls ................................................ [ACLs: 0]
| o- luns ................................................ [LUNs: 0]
o- vhost ................................................ [Targets: 0]
Fixes: e9c03af21c
("configfs: calculate the symlink target only once")
Signed-off-by: Honggang Li <honli@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
270 lines
6.7 KiB
C
270 lines
6.7 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 configfs_get_target_path(struct config_item *item,
|
|
struct config_item *target, char *path)
|
|
{
|
|
int depth, size;
|
|
char *s;
|
|
|
|
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 create_link(struct config_item *parent_item,
|
|
struct config_item *item,
|
|
struct dentry *dentry)
|
|
{
|
|
struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
|
|
char *body;
|
|
int ret;
|
|
|
|
if (!configfs_dirent_is_ready(target_sd))
|
|
return -ENOENT;
|
|
|
|
body = kzalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!body)
|
|
return -ENOMEM;
|
|
|
|
configfs_get(target_sd);
|
|
spin_lock(&configfs_dirent_lock);
|
|
if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
|
|
spin_unlock(&configfs_dirent_lock);
|
|
configfs_put(target_sd);
|
|
kfree(body);
|
|
return -ENOENT;
|
|
}
|
|
target_sd->s_links++;
|
|
spin_unlock(&configfs_dirent_lock);
|
|
ret = configfs_get_target_path(parent_item, item, body);
|
|
if (!ret)
|
|
ret = configfs_create_link(target_sd, parent_item->ci_dentry,
|
|
dentry, body);
|
|
if (ret) {
|
|
spin_lock(&configfs_dirent_lock);
|
|
target_sd->s_links--;
|
|
spin_unlock(&configfs_dirent_lock);
|
|
configfs_put(target_sd);
|
|
kfree(body);
|
|
}
|
|
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
|
|
*/
|
|
if (!configfs_dirent_is_ready(sd))
|
|
return -ENOENT;
|
|
|
|
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;
|
|
|
|
/*
|
|
* This is really sick. What they wanted was a hybrid of
|
|
* link(2) and symlink(2) - they wanted the target resolved
|
|
* at syscall time (as link(2) would've done), be a directory
|
|
* (which link(2) would've refused to do) *AND* be a deep
|
|
* fucking magic, making the target busy from rmdir POV.
|
|
* symlink(2) is nothing of that sort, and the locking it
|
|
* gets matches the normal symlink(2) semantics. Without
|
|
* attempts to resolve the target (which might very well
|
|
* not even exist yet) done prior to locking the parent
|
|
* directory. This perversion, OTOH, needs to resolve
|
|
* the target, which would lead to obvious deadlocks if
|
|
* attempted with any directories locked.
|
|
*
|
|
* Unfortunately, that garbage is userland ABI and we should've
|
|
* said "no" back in 2005. Too late now, so we get to
|
|
* play very ugly games with locking.
|
|
*
|
|
* Try *ANYTHING* of that sort in new code, and you will
|
|
* really regret it. Just ask yourself - what could a BOFH
|
|
* do to me and do I want to find it out first-hand?
|
|
*
|
|
* AV, a thoroughly annoyed bastard.
|
|
*/
|
|
inode_unlock(dir);
|
|
ret = get_target(symname, &path, &target_item, dentry->d_sb);
|
|
inode_lock(dir);
|
|
if (ret)
|
|
goto out_put;
|
|
|
|
if (dentry->d_inode || d_unhashed(dentry))
|
|
ret = -EEXIST;
|
|
else
|
|
ret = inode_permission(dir, MAY_WRITE | MAY_EXEC);
|
|
if (!ret)
|
|
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);
|
|
return ret;
|
|
}
|
|
|
|
int configfs_unlink(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
struct configfs_dirent *sd = dentry->d_fsdata, *target_sd;
|
|
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;
|
|
|
|
target_sd = 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
|
|
* decrementing target's ->s_links, 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,
|
|
target_sd->s_element);
|
|
|
|
spin_lock(&configfs_dirent_lock);
|
|
target_sd->s_links--;
|
|
spin_unlock(&configfs_dirent_lock);
|
|
configfs_put(target_sd);
|
|
|
|
config_item_put(parent_item);
|
|
|
|
ret = 0;
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
const struct inode_operations configfs_symlink_inode_operations = {
|
|
.get_link = simple_get_link,
|
|
.setattr = configfs_setattr,
|
|
};
|
|
|