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