linux/fs/configfs/inode.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * inode.c - basic inode and dentry operations.
   4 *
   5 * Based on sysfs:
   6 *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
   7 *
   8 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
   9 *
  10 * Please see Documentation/filesystems/configfs.rst for more
  11 * information.
  12 */
  13
  14#undef DEBUG
  15
  16#include <linux/pagemap.h>
  17#include <linux/namei.h>
  18#include <linux/backing-dev.h>
  19#include <linux/capability.h>
  20#include <linux/sched.h>
  21#include <linux/lockdep.h>
  22#include <linux/slab.h>
  23
  24#include <linux/configfs.h>
  25#include "configfs_internal.h"
  26
  27#ifdef CONFIG_LOCKDEP
  28static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  29#endif
  30
  31static const struct address_space_operations configfs_aops = {
  32        .readpage       = simple_readpage,
  33        .write_begin    = simple_write_begin,
  34        .write_end      = simple_write_end,
  35};
  36
  37static const struct inode_operations configfs_inode_operations ={
  38        .setattr        = configfs_setattr,
  39};
  40
  41int configfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
  42                     struct iattr *iattr)
  43{
  44        struct inode * inode = d_inode(dentry);
  45        struct configfs_dirent * sd = dentry->d_fsdata;
  46        struct iattr * sd_iattr;
  47        unsigned int ia_valid = iattr->ia_valid;
  48        int error;
  49
  50        if (!sd)
  51                return -EINVAL;
  52
  53        sd_iattr = sd->s_iattr;
  54        if (!sd_iattr) {
  55                /* setting attributes for the first time, allocate now */
  56                sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  57                if (!sd_iattr)
  58                        return -ENOMEM;
  59                /* assign default attributes */
  60                sd_iattr->ia_mode = sd->s_mode;
  61                sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  62                sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  63                sd_iattr->ia_atime = sd_iattr->ia_mtime =
  64                        sd_iattr->ia_ctime = current_time(inode);
  65                sd->s_iattr = sd_iattr;
  66        }
  67        /* attributes were changed atleast once in past */
  68
  69        error = simple_setattr(mnt_userns, dentry, iattr);
  70        if (error)
  71                return error;
  72
  73        if (ia_valid & ATTR_UID)
  74                sd_iattr->ia_uid = iattr->ia_uid;
  75        if (ia_valid & ATTR_GID)
  76                sd_iattr->ia_gid = iattr->ia_gid;
  77        if (ia_valid & ATTR_ATIME)
  78                sd_iattr->ia_atime = iattr->ia_atime;
  79        if (ia_valid & ATTR_MTIME)
  80                sd_iattr->ia_mtime = iattr->ia_mtime;
  81        if (ia_valid & ATTR_CTIME)
  82                sd_iattr->ia_ctime = iattr->ia_ctime;
  83        if (ia_valid & ATTR_MODE) {
  84                umode_t mode = iattr->ia_mode;
  85
  86                if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  87                        mode &= ~S_ISGID;
  88                sd_iattr->ia_mode = sd->s_mode = mode;
  89        }
  90
  91        return error;
  92}
  93
  94static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
  95{
  96        inode->i_mode = mode;
  97        inode->i_atime = inode->i_mtime =
  98                inode->i_ctime = current_time(inode);
  99}
 100
 101static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 102{
 103        inode->i_mode = iattr->ia_mode;
 104        inode->i_uid = iattr->ia_uid;
 105        inode->i_gid = iattr->ia_gid;
 106        inode->i_atime = iattr->ia_atime;
 107        inode->i_mtime = iattr->ia_mtime;
 108        inode->i_ctime = iattr->ia_ctime;
 109}
 110
 111struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 112                                 struct super_block *s)
 113{
 114        struct inode * inode = new_inode(s);
 115        if (inode) {
 116                inode->i_ino = get_next_ino();
 117                inode->i_mapping->a_ops = &configfs_aops;
 118                inode->i_op = &configfs_inode_operations;
 119
 120                if (sd->s_iattr) {
 121                        /* sysfs_dirent has non-default attributes
 122                         * get them for the new inode from persistent copy
 123                         * in sysfs_dirent
 124                         */
 125                        set_inode_attr(inode, sd->s_iattr);
 126                } else
 127                        set_default_inode_attr(inode, mode);
 128        }
 129        return inode;
 130}
 131
 132#ifdef CONFIG_LOCKDEP
 133
 134static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 135                                          struct inode *inode)
 136{
 137        int depth = sd->s_depth;
 138
 139        if (depth > 0) {
 140                if (depth <= ARRAY_SIZE(default_group_class)) {
 141                        lockdep_set_class(&inode->i_rwsem,
 142                                          &default_group_class[depth - 1]);
 143                } else {
 144                        /*
 145                         * In practice the maximum level of locking depth is
 146                         * already reached. Just inform about possible reasons.
 147                         */
 148                        pr_info("Too many levels of inodes for the locking correctness validator.\n");
 149                        pr_info("Spurious warnings may appear.\n");
 150                }
 151        }
 152}
 153
 154#else /* CONFIG_LOCKDEP */
 155
 156static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 157                                          struct inode *inode)
 158{
 159}
 160
 161#endif /* CONFIG_LOCKDEP */
 162
 163struct inode *configfs_create(struct dentry *dentry, umode_t mode)
 164{
 165        struct inode *inode = NULL;
 166        struct configfs_dirent *sd;
 167        struct inode *p_inode;
 168
 169        if (!dentry)
 170                return ERR_PTR(-ENOENT);
 171
 172        if (d_really_is_positive(dentry))
 173                return ERR_PTR(-EEXIST);
 174
 175        sd = dentry->d_fsdata;
 176        inode = configfs_new_inode(mode, sd, dentry->d_sb);
 177        if (!inode)
 178                return ERR_PTR(-ENOMEM);
 179
 180        p_inode = d_inode(dentry->d_parent);
 181        p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
 182        configfs_set_inode_lock_class(sd, inode);
 183        return inode;
 184}
 185
 186/*
 187 * Get the name for corresponding element represented by the given configfs_dirent
 188 */
 189const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 190{
 191        struct configfs_attribute *attr;
 192
 193        BUG_ON(!sd || !sd->s_element);
 194
 195        /* These always have a dentry, so use that */
 196        if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 197                return sd->s_dentry->d_name.name;
 198
 199        if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
 200                attr = sd->s_element;
 201                return attr->ca_name;
 202        }
 203        return NULL;
 204}
 205
 206
 207/*
 208 * Unhashes the dentry corresponding to given configfs_dirent
 209 * Called with parent inode's i_mutex held.
 210 */
 211void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 212{
 213        struct dentry * dentry = sd->s_dentry;
 214
 215        if (dentry) {
 216                spin_lock(&dentry->d_lock);
 217                if (simple_positive(dentry)) {
 218                        dget_dlock(dentry);
 219                        __d_drop(dentry);
 220                        spin_unlock(&dentry->d_lock);
 221                        simple_unlink(d_inode(parent), dentry);
 222                } else
 223                        spin_unlock(&dentry->d_lock);
 224        }
 225}
 226
 227void configfs_hash_and_remove(struct dentry * dir, const char * name)
 228{
 229        struct configfs_dirent * sd;
 230        struct configfs_dirent * parent_sd = dir->d_fsdata;
 231
 232        if (d_really_is_negative(dir))
 233                /* no inode means this hasn't been made visible yet */
 234                return;
 235
 236        inode_lock(d_inode(dir));
 237        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 238                if (!sd->s_element)
 239                        continue;
 240                if (!strcmp(configfs_get_name(sd), name)) {
 241                        spin_lock(&configfs_dirent_lock);
 242                        list_del_init(&sd->s_sibling);
 243                        spin_unlock(&configfs_dirent_lock);
 244                        configfs_drop_dentry(sd, dir);
 245                        configfs_put(sd);
 246                        break;
 247                }
 248        }
 249        inode_unlock(d_inode(dir));
 250}
 251