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 28 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH]; 29 #endif 30 31 static 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 37 static const struct inode_operations configfs_inode_operations ={ 38 .setattr = configfs_setattr, 39 }; 40 41 int 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 94 static 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 } 100 101 static 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 } 110 111 struct 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 133 134 static 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 */ 155 156 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 157 struct inode *inode) 158 { 159 } 160 161 #endif /* CONFIG_LOCKDEP */ 162 163 struct 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 */ 189 const 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 */ 211 void 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 } 226 227 void 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