/* * fs/sysfs/inode.c - basic sysfs inode and dentry operations * * Copyright (c) 2001-3 Patrick Mochel * Copyright (c) 2007 SUSE Linux Products GmbH * Copyright (c) 2007 Tejun Heo <teheo@suse.de> * * This file is released under the GPLv2. * * Please see Documentation/filesystems/sysfs.txt for more information. */ #undef DEBUG #include <linux/pagemap.h> #include <linux/namei.h> #include <linux/backing-dev.h> #include <linux/capability.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/xattr.h> #include <linux/security.h> #include "sysfs.h" extern struct super_block * sysfs_sb; static const struct address_space_operations sysfs_aops = { .readpage = simple_readpage, .write_begin = simple_write_begin, .write_end = simple_write_end, }; static struct backing_dev_info sysfs_backing_dev_info = { .name = "sysfs", .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; static const struct inode_operations sysfs_inode_operations ={ .permission = sysfs_permission, .setattr = sysfs_setattr, .getattr = sysfs_getattr, .setxattr = sysfs_setxattr, }; int __init sysfs_inode_init(void) { return bdi_init(&sysfs_backing_dev_info); } static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd) { struct sysfs_inode_attrs *attrs; struct iattr *iattrs; attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL); if (!attrs) return NULL; iattrs = &attrs->ia_iattr; /* assign default attributes */ iattrs->ia_mode = sd->s_mode; iattrs->ia_uid = 0; iattrs->ia_gid = 0; iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME; return attrs; } int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr) { struct sysfs_inode_attrs *sd_attrs; struct iattr *iattrs; unsigned int ia_valid = iattr->ia_valid; sd_attrs = sd->s_iattr; if (!sd_attrs) { /* setting attributes for the first time, allocate now */ sd_attrs = sysfs_init_inode_attrs(sd); if (!sd_attrs) return -ENOMEM; sd->s_iattr = sd_attrs; } else { /* attributes were changed at least once in past */ iattrs = &sd_attrs->ia_iattr; if (ia_valid & ATTR_UID) iattrs->ia_uid = iattr->ia_uid; if (ia_valid & ATTR_GID) iattrs->ia_gid = iattr->ia_gid; if (ia_valid & ATTR_ATIME) iattrs->ia_atime = iattr->ia_atime; if (ia_valid & ATTR_MTIME) iattrs->ia_mtime = iattr->ia_mtime; if (ia_valid & ATTR_CTIME) iattrs->ia_ctime = iattr->ia_ctime; if (ia_valid & ATTR_MODE) { umode_t mode = iattr->ia_mode; iattrs->ia_mode = sd->s_mode = mode; } } return 0; } int sysfs_setattr(struct dentry *dentry, struct iattr *iattr) { struct inode *inode = dentry->d_inode; struct sysfs_dirent *sd = dentry->d_fsdata; int error; if (!sd) return -EINVAL; error = inode_change_ok(inode, iattr); if (error) return error; iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */ error = inode_setattr(inode, iattr); if (error) return error; mutex_lock(&sysfs_mutex); error = sysfs_sd_setattr(sd, iattr); mutex_unlock(&sysfs_mutex); return error; } static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len) { struct sysfs_inode_attrs *iattrs; void *old_secdata; size_t old_secdata_len; iattrs = sd->s_iattr; if (!iattrs) iattrs = sysfs_init_inode_attrs(sd); if (!iattrs) return -ENOMEM; old_secdata = iattrs->ia_secdata; old_secdata_len = iattrs->ia_secdata_len; iattrs->ia_secdata = *secdata; iattrs->ia_secdata_len = *secdata_len; *secdata = old_secdata; *secdata_len = old_secdata_len; return 0; } int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { struct sysfs_dirent *sd = dentry->d_fsdata; void *secdata; int error; u32 secdata_len = 0; if (!sd) return -EINVAL; if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) { const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; error = security_inode_setsecurity(dentry->d_inode, suffix, value, size, flags); if (error) goto out; error = security_inode_getsecctx(dentry->d_inode, &secdata, &secdata_len); if (error) goto out; mutex_lock(&sysfs_mutex); error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len); mutex_unlock(&sysfs_mutex); if (secdata) security_release_secctx(secdata, secdata_len); } else return -EINVAL; out: return error; } static inline void set_default_inode_attr(struct inode * inode, mode_t mode) { inode->i_mode = mode; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; } static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) { inode->i_uid = iattr->ia_uid; inode->i_gid = iattr->ia_gid; inode->i_atime = iattr->ia_atime; inode->i_mtime = iattr->ia_mtime; inode->i_ctime = iattr->ia_ctime; } static int sysfs_count_nlink(struct sysfs_dirent *sd) { struct sysfs_dirent *child; int nr = 0; for (child = sd->s_dir.children; child; child = child->s_sibling) if (sysfs_type(child) == SYSFS_DIR) nr++; return nr + 2; } static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode) { struct sysfs_inode_attrs *iattrs = sd->s_iattr; inode->i_mode = sd->s_mode; if (iattrs) { /* sysfs_dirent has non-default attributes * get them from persistent copy in sysfs_dirent */ set_inode_attr(inode, &iattrs->ia_iattr); security_inode_notifysecctx(inode, iattrs->ia_secdata, iattrs->ia_secdata_len); } if (sysfs_type(sd) == SYSFS_DIR) inode->i_nlink = sysfs_count_nlink(sd); } int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { struct sysfs_dirent *sd = dentry->d_fsdata; struct inode *inode = dentry->d_inode; mutex_lock(&sysfs_mutex); sysfs_refresh_inode(sd, inode); mutex_unlock(&sysfs_mutex); generic_fillattr(inode, stat); return 0; } static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode) { struct bin_attribute *bin_attr; inode->i_private = sysfs_get(sd); inode->i_mapping->a_ops = &sysfs_aops; inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info; inode->i_op = &sysfs_inode_operations; set_default_inode_attr(inode, sd->s_mode); sysfs_refresh_inode(sd, inode); /* initialize inode according to type */ switch (sysfs_type(sd)) { case SYSFS_DIR: inode->i_op = &sysfs_dir_inode_operations; inode->i_fop = &sysfs_dir_operations; break; case SYSFS_KOBJ_ATTR: inode->i_size = PAGE_SIZE; inode->i_fop = &sysfs_file_operations; break; case SYSFS_KOBJ_BIN_ATTR: bin_attr = sd->s_bin_attr.bin_attr; inode->i_size = bin_attr->size; inode->i_fop = &bin_fops; break; case SYSFS_KOBJ_LINK: inode->i_op = &sysfs_symlink_inode_operations; break; default: BUG(); } unlock_new_inode(inode); } /** * sysfs_get_inode - get inode for sysfs_dirent * @sd: sysfs_dirent to allocate inode for * * Get inode for @sd. If such inode doesn't exist, a new inode * is allocated and basics are initialized. New inode is * returned locked. * * LOCKING: * Kernel thread context (may sleep). * * RETURNS: * Pointer to allocated inode on success, NULL on failure. */ struct inode * sysfs_get_inode(struct sysfs_dirent *sd) { struct inode *inode; inode = iget_locked(sysfs_sb, sd->s_ino); if (inode && (inode->i_state & I_NEW)) sysfs_init_inode(sd, inode); return inode; } /* * The sysfs_dirent serves as both an inode and a directory entry for sysfs. * To prevent the sysfs inode numbers from being freed prematurely we take a * reference to sysfs_dirent from the sysfs inode. A * super_operations.delete_inode() implementation is needed to drop that * reference upon inode destruction. */ void sysfs_delete_inode(struct inode *inode) { struct sysfs_dirent *sd = inode->i_private; truncate_inode_pages(&inode->i_data, 0); clear_inode(inode); sysfs_put(sd); } int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name) { struct sysfs_addrm_cxt acxt; struct sysfs_dirent *sd; if (!dir_sd) return -ENOENT; sysfs_addrm_start(&acxt, dir_sd); sd = sysfs_find_dirent(dir_sd, name); if (sd) sysfs_remove_one(&acxt, sd); sysfs_addrm_finish(&acxt); if (sd) return 0; else return -ENOENT; } int sysfs_permission(struct inode *inode, int mask) { struct sysfs_dirent *sd = inode->i_private; mutex_lock(&sysfs_mutex); sysfs_refresh_inode(sd, inode); mutex_unlock(&sysfs_mutex); return generic_permission(inode, mask, NULL); }