Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 1 | /* -*- mode: c; c-basic-offset: 8; -*- |
| 2 | * vim: noexpandtab sw=8 ts=8 sts=0: |
| 3 | * |
| 4 | * symlink.c - operations for configfs symlinks. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * This program is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public |
| 17 | * License along with this program; if not, write to the |
| 18 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 19 | * Boston, MA 021110-1307, USA. |
| 20 | * |
| 21 | * Based on sysfs: |
| 22 | * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel |
| 23 | * |
| 24 | * configfs Copyright (C) 2005 Oracle. All rights reserved. |
| 25 | */ |
| 26 | |
| 27 | #include <linux/fs.h> |
| 28 | #include <linux/module.h> |
| 29 | #include <linux/namei.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 30 | #include <linux/slab.h> |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 31 | |
| 32 | #include <linux/configfs.h> |
| 33 | #include "configfs_internal.h" |
| 34 | |
Louis Rilling | 9a73d78 | 2008-06-20 14:09:22 +0200 | [diff] [blame] | 35 | /* Protects attachments of new symlinks */ |
| 36 | DEFINE_MUTEX(configfs_symlink_mutex); |
| 37 | |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 38 | static int item_depth(struct config_item * item) |
| 39 | { |
| 40 | struct config_item * p = item; |
| 41 | int depth = 0; |
| 42 | do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p)); |
| 43 | return depth; |
| 44 | } |
| 45 | |
| 46 | static int item_path_length(struct config_item * item) |
| 47 | { |
| 48 | struct config_item * p = item; |
| 49 | int length = 1; |
| 50 | do { |
| 51 | length += strlen(config_item_name(p)) + 1; |
| 52 | p = p->ci_parent; |
| 53 | } while (p && !configfs_is_root(p)); |
| 54 | return length; |
| 55 | } |
| 56 | |
| 57 | static void fill_item_path(struct config_item * item, char * buffer, int length) |
| 58 | { |
| 59 | struct config_item * p; |
| 60 | |
| 61 | --length; |
| 62 | for (p = item; p && !configfs_is_root(p); p = p->ci_parent) { |
| 63 | int cur = strlen(config_item_name(p)); |
| 64 | |
| 65 | /* back up enough to print this bus id with '/' */ |
| 66 | length -= cur; |
Guenter Roeck | 8f1756a | 2018-07-01 13:56:54 -0700 | [diff] [blame^] | 67 | memcpy(buffer + length, config_item_name(p), cur); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 68 | *(buffer + --length) = '/'; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | static int create_link(struct config_item *parent_item, |
Joel Becker | e7515d0 | 2006-03-10 11:42:30 -0800 | [diff] [blame] | 73 | struct config_item *item, |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 74 | struct dentry *dentry) |
| 75 | { |
| 76 | struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata; |
| 77 | struct configfs_symlink *sl; |
| 78 | int ret; |
| 79 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 80 | ret = -ENOENT; |
| 81 | if (!configfs_dirent_is_ready(target_sd)) |
| 82 | goto out; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 83 | ret = -ENOMEM; |
| 84 | sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); |
| 85 | if (sl) { |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 86 | spin_lock(&configfs_dirent_lock); |
Louis Rilling | 4768e9b | 2008-06-23 14:16:17 +0200 | [diff] [blame] | 87 | if (target_sd->s_type & CONFIGFS_USET_DROPPING) { |
| 88 | spin_unlock(&configfs_dirent_lock); |
Louis Rilling | 4768e9b | 2008-06-23 14:16:17 +0200 | [diff] [blame] | 89 | kfree(sl); |
| 90 | return -ENOENT; |
| 91 | } |
Nicholas Bellinger | a6d6282 | 2017-06-08 04:51:54 +0000 | [diff] [blame] | 92 | sl->sl_target = config_item_get(item); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 93 | list_add(&sl->sl_list, &target_sd->s_links); |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 94 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 95 | ret = configfs_create_link(sl, parent_item->ci_dentry, |
| 96 | dentry); |
| 97 | if (ret) { |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 98 | spin_lock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 99 | list_del_init(&sl->sl_list); |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 100 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 101 | config_item_put(item); |
| 102 | kfree(sl); |
| 103 | } |
| 104 | } |
| 105 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 106 | out: |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 107 | return ret; |
| 108 | } |
| 109 | |
| 110 | |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 111 | static int get_target(const char *symname, struct path *path, |
Al Viro | b7c177f | 2012-03-17 16:24:54 -0400 | [diff] [blame] | 112 | struct config_item **target, struct super_block *sb) |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 113 | { |
| 114 | int ret; |
| 115 | |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 116 | ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 117 | if (!ret) { |
Al Viro | b7c177f | 2012-03-17 16:24:54 -0400 | [diff] [blame] | 118 | if (path->dentry->d_sb == sb) { |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 119 | *target = configfs_get_config_item(path->dentry); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 120 | if (!*target) { |
| 121 | ret = -ENOENT; |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 122 | path_put(path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 123 | } |
Al Viro | 9b6e310 | 2010-01-13 22:10:57 -0500 | [diff] [blame] | 124 | } else { |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 125 | ret = -EPERM; |
Al Viro | 9b6e310 | 2010-01-13 22:10:57 -0500 | [diff] [blame] | 126 | path_put(path); |
| 127 | } |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 128 | } |
| 129 | |
| 130 | return ret; |
| 131 | } |
| 132 | |
| 133 | |
| 134 | int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
| 135 | { |
| 136 | int ret; |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 137 | struct path path; |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 138 | struct configfs_dirent *sd; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 139 | struct config_item *parent_item; |
Subrata Modak | 3c48f23 | 2009-04-19 01:10:03 +0530 | [diff] [blame] | 140 | struct config_item *target_item = NULL; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 141 | struct config_item_type *type; |
| 142 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 143 | sd = dentry->d_parent->d_fsdata; |
| 144 | /* |
| 145 | * Fake invisibility if dir belongs to a group/default groups hierarchy |
| 146 | * being attached |
| 147 | */ |
| 148 | ret = -ENOENT; |
| 149 | if (!configfs_dirent_is_ready(sd)) |
| 150 | goto out; |
| 151 | |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 152 | parent_item = configfs_get_config_item(dentry->d_parent); |
| 153 | type = parent_item->ci_type; |
| 154 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 155 | ret = -EPERM; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 156 | if (!type || !type->ct_item_ops || |
| 157 | !type->ct_item_ops->allow_link) |
| 158 | goto out_put; |
| 159 | |
Al Viro | b7c177f | 2012-03-17 16:24:54 -0400 | [diff] [blame] | 160 | ret = get_target(symname, &path, &target_item, dentry->d_sb); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 161 | if (ret) |
| 162 | goto out_put; |
| 163 | |
| 164 | ret = type->ct_item_ops->allow_link(parent_item, target_item); |
Louis Rilling | e752065 | 2008-06-12 17:26:47 +0200 | [diff] [blame] | 165 | if (!ret) { |
Louis Rilling | 9a73d78 | 2008-06-20 14:09:22 +0200 | [diff] [blame] | 166 | mutex_lock(&configfs_symlink_mutex); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 167 | ret = create_link(parent_item, target_item, dentry); |
Louis Rilling | 9a73d78 | 2008-06-20 14:09:22 +0200 | [diff] [blame] | 168 | mutex_unlock(&configfs_symlink_mutex); |
Louis Rilling | e752065 | 2008-06-12 17:26:47 +0200 | [diff] [blame] | 169 | if (ret && type->ct_item_ops->drop_link) |
| 170 | type->ct_item_ops->drop_link(parent_item, |
| 171 | target_item); |
| 172 | } |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 173 | |
| 174 | config_item_put(target_item); |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 175 | path_put(&path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 176 | |
| 177 | out_put: |
| 178 | config_item_put(parent_item); |
| 179 | |
| 180 | out: |
| 181 | return ret; |
| 182 | } |
| 183 | |
| 184 | int configfs_unlink(struct inode *dir, struct dentry *dentry) |
| 185 | { |
| 186 | struct configfs_dirent *sd = dentry->d_fsdata; |
| 187 | struct configfs_symlink *sl; |
| 188 | struct config_item *parent_item; |
| 189 | struct config_item_type *type; |
| 190 | int ret; |
| 191 | |
| 192 | ret = -EPERM; /* What lack-of-symlink returns */ |
| 193 | if (!(sd->s_type & CONFIGFS_ITEM_LINK)) |
| 194 | goto out; |
| 195 | |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 196 | sl = sd->s_element; |
| 197 | |
| 198 | parent_item = configfs_get_config_item(dentry->d_parent); |
| 199 | type = parent_item->ci_type; |
| 200 | |
Louis Rilling | 6f61076 | 2008-06-16 19:00:58 +0200 | [diff] [blame] | 201 | spin_lock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 202 | list_del_init(&sd->s_sibling); |
Louis Rilling | 6f61076 | 2008-06-16 19:00:58 +0200 | [diff] [blame] | 203 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 204 | configfs_drop_dentry(sd, dentry->d_parent); |
| 205 | dput(dentry); |
| 206 | configfs_put(sd); |
| 207 | |
| 208 | /* |
| 209 | * drop_link() must be called before |
| 210 | * list_del_init(&sl->sl_list), so that the order of |
| 211 | * drop_link(this, target) and drop_item(target) is preserved. |
| 212 | */ |
| 213 | if (type && type->ct_item_ops && |
| 214 | type->ct_item_ops->drop_link) |
| 215 | type->ct_item_ops->drop_link(parent_item, |
| 216 | sl->sl_target); |
| 217 | |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 218 | spin_lock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 219 | list_del_init(&sl->sl_list); |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 220 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 221 | |
| 222 | /* Put reference from create_link() */ |
| 223 | config_item_put(sl->sl_target); |
| 224 | kfree(sl); |
| 225 | |
| 226 | config_item_put(parent_item); |
| 227 | |
| 228 | ret = 0; |
| 229 | |
| 230 | out: |
| 231 | return ret; |
| 232 | } |
| 233 | |
| 234 | static int configfs_get_target_path(struct config_item * item, struct config_item * target, |
| 235 | char *path) |
| 236 | { |
| 237 | char * s; |
| 238 | int depth, size; |
| 239 | |
| 240 | depth = item_depth(item); |
| 241 | size = item_path_length(target) + depth * 3 - 1; |
| 242 | if (size > PATH_MAX) |
| 243 | return -ENAMETOOLONG; |
| 244 | |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 245 | pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 246 | |
| 247 | for (s = path; depth--; s += 3) |
| 248 | strcpy(s,"../"); |
| 249 | |
| 250 | fill_item_path(target, path, size); |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 251 | pr_debug("%s: path = '%s'\n", __func__, path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 252 | |
| 253 | return 0; |
| 254 | } |
| 255 | |
| 256 | static int configfs_getlink(struct dentry *dentry, char * path) |
| 257 | { |
| 258 | struct config_item *item, *target_item; |
| 259 | int error = 0; |
| 260 | |
| 261 | item = configfs_get_config_item(dentry->d_parent); |
| 262 | if (!item) |
| 263 | return -EINVAL; |
| 264 | |
| 265 | target_item = configfs_get_config_item(dentry); |
| 266 | if (!target_item) { |
| 267 | config_item_put(item); |
| 268 | return -EINVAL; |
| 269 | } |
| 270 | |
| 271 | down_read(&configfs_rename_sem); |
| 272 | error = configfs_get_target_path(item, target_item, path); |
| 273 | up_read(&configfs_rename_sem); |
| 274 | |
| 275 | config_item_put(item); |
| 276 | config_item_put(target_item); |
| 277 | return error; |
| 278 | |
| 279 | } |
| 280 | |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 281 | static const char *configfs_get_link(struct dentry *dentry, |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 282 | struct inode *inode, |
| 283 | struct delayed_call *done) |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 284 | { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 285 | char *body; |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 286 | int error; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 287 | |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 288 | if (!dentry) |
| 289 | return ERR_PTR(-ECHILD); |
| 290 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 291 | body = kzalloc(PAGE_SIZE, GFP_KERNEL); |
| 292 | if (!body) |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 293 | return ERR_PTR(-ENOMEM); |
| 294 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 295 | error = configfs_getlink(dentry, body); |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 296 | if (!error) { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 297 | set_delayed_call(done, kfree_link, body); |
| 298 | return body; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 299 | } |
| 300 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 301 | kfree(body); |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 302 | return ERR_PTR(error); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 303 | } |
| 304 | |
Arjan van de Ven | 754661f | 2007-02-12 00:55:38 -0800 | [diff] [blame] | 305 | const struct inode_operations configfs_symlink_inode_operations = { |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 306 | .get_link = configfs_get_link, |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 307 | .readlink = generic_readlink, |
Joel Becker | 3d0f89b | 2006-01-25 13:31:07 -0800 | [diff] [blame] | 308 | .setattr = configfs_setattr, |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 309 | }; |
| 310 | |