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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * fs/kernfs/inode.c - kernfs inode implementation
- *
- * Copyright (c) 2001-3 Patrick Mochel
- * Copyright (c) 2007 SUSE Linux Products GmbH
- * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
- */
- #include <linux/pagemap.h>
- #include <linux/backing-dev.h>
- #include <linux/capability.h>
- #include <linux/errno.h>
- #include <linux/slab.h>
- #include <linux/xattr.h>
- #include <linux/security.h>
- #include "kernfs-internal.h"
- static const struct address_space_operations kernfs_aops = {
- .readpage = simple_readpage,
- .write_begin = simple_write_begin,
- .write_end = simple_write_end,
- };
- static const struct inode_operations kernfs_iops = {
- .permission = kernfs_iop_permission,
- .setattr = kernfs_iop_setattr,
- .getattr = kernfs_iop_getattr,
- .listxattr = kernfs_iop_listxattr,
- };
- static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
- {
- static DEFINE_MUTEX(iattr_mutex);
- struct kernfs_iattrs *ret;
- mutex_lock(&iattr_mutex);
- if (kn->iattr || !alloc)
- goto out_unlock;
- kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
- if (!kn->iattr)
- goto out_unlock;
- /* assign default attributes */
- kn->iattr->ia_uid = GLOBAL_ROOT_UID;
- kn->iattr->ia_gid = GLOBAL_ROOT_GID;
- ktime_get_real_ts64(&kn->iattr->ia_atime);
- kn->iattr->ia_mtime = kn->iattr->ia_atime;
- kn->iattr->ia_ctime = kn->iattr->ia_atime;
- simple_xattrs_init(&kn->iattr->xattrs);
- atomic_set(&kn->iattr->nr_user_xattrs, 0);
- atomic_set(&kn->iattr->user_xattr_size, 0);
- out_unlock:
- ret = kn->iattr;
- mutex_unlock(&iattr_mutex);
- return ret;
- }
- static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
- {
- return __kernfs_iattrs(kn, 1);
- }
- static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
- {
- return __kernfs_iattrs(kn, 0);
- }
- int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
- {
- struct kernfs_iattrs *attrs;
- unsigned int ia_valid = iattr->ia_valid;
- attrs = kernfs_iattrs(kn);
- if (!attrs)
- return -ENOMEM;
- if (ia_valid & ATTR_UID)
- attrs->ia_uid = iattr->ia_uid;
- if (ia_valid & ATTR_GID)
- attrs->ia_gid = iattr->ia_gid;
- if (ia_valid & ATTR_ATIME)
- attrs->ia_atime = iattr->ia_atime;
- if (ia_valid & ATTR_MTIME)
- attrs->ia_mtime = iattr->ia_mtime;
- if (ia_valid & ATTR_CTIME)
- attrs->ia_ctime = iattr->ia_ctime;
- if (ia_valid & ATTR_MODE)
- kn->mode = iattr->ia_mode;
- return 0;
- }
- /**
- * kernfs_setattr - set iattr on a node
- * @kn: target node
- * @iattr: iattr to set
- *
- * Returns 0 on success, -errno on failure.
- */
- int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
- {
- int ret;
- mutex_lock(&kernfs_mutex);
- ret = __kernfs_setattr(kn, iattr);
- mutex_unlock(&kernfs_mutex);
- return ret;
- }
- int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
- {
- struct inode *inode = d_inode(dentry);
- struct kernfs_node *kn = inode->i_private;
- int error;
- if (!kn)
- return -EINVAL;
- mutex_lock(&kernfs_mutex);
- error = setattr_prepare(dentry, iattr);
- if (error)
- goto out;
- error = __kernfs_setattr(kn, iattr);
- if (error)
- goto out;
- /* this ignores size changes */
- setattr_copy(inode, iattr);
- out:
- mutex_unlock(&kernfs_mutex);
- return error;
- }
- ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
- {
- struct kernfs_node *kn = kernfs_dentry_node(dentry);
- struct kernfs_iattrs *attrs;
- attrs = kernfs_iattrs(kn);
- if (!attrs)
- return -ENOMEM;
- return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
- }
- static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
- {
- inode->i_mode = mode;
- inode->i_atime = inode->i_mtime =
- inode->i_ctime = current_time(inode);
- }
- static inline void set_inode_attr(struct inode *inode,
- struct kernfs_iattrs *attrs)
- {
- inode->i_uid = attrs->ia_uid;
- inode->i_gid = attrs->ia_gid;
- inode->i_atime = attrs->ia_atime;
- inode->i_mtime = attrs->ia_mtime;
- inode->i_ctime = attrs->ia_ctime;
- }
- static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
- {
- struct kernfs_iattrs *attrs = kn->iattr;
- inode->i_mode = kn->mode;
- if (attrs)
- /*
- * kernfs_node has non-default attributes get them from
- * persistent copy in kernfs_node.
- */
- set_inode_attr(inode, attrs);
- if (kernfs_type(kn) == KERNFS_DIR)
- set_nlink(inode, kn->dir.subdirs + 2);
- }
- int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
- u32 request_mask, unsigned int query_flags)
- {
- struct inode *inode = d_inode(path->dentry);
- struct kernfs_node *kn = inode->i_private;
- mutex_lock(&kernfs_mutex);
- kernfs_refresh_inode(kn, inode);
- mutex_unlock(&kernfs_mutex);
- generic_fillattr(inode, stat);
- return 0;
- }
- static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
- {
- kernfs_get(kn);
- inode->i_private = kn;
- inode->i_mapping->a_ops = &kernfs_aops;
- inode->i_op = &kernfs_iops;
- inode->i_generation = kernfs_gen(kn);
- set_default_inode_attr(inode, kn->mode);
- kernfs_refresh_inode(kn, inode);
- /* initialize inode according to type */
- switch (kernfs_type(kn)) {
- case KERNFS_DIR:
- inode->i_op = &kernfs_dir_iops;
- inode->i_fop = &kernfs_dir_fops;
- if (kn->flags & KERNFS_EMPTY_DIR)
- make_empty_dir_inode(inode);
- break;
- case KERNFS_FILE:
- inode->i_size = kn->attr.size;
- inode->i_fop = &kernfs_file_fops;
- break;
- case KERNFS_LINK:
- inode->i_op = &kernfs_symlink_iops;
- break;
- default:
- BUG();
- }
- unlock_new_inode(inode);
- }
- /**
- * kernfs_get_inode - get inode for kernfs_node
- * @sb: super block
- * @kn: kernfs_node to allocate inode for
- *
- * Get inode for @kn. 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 *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
- {
- struct inode *inode;
- inode = iget_locked(sb, kernfs_ino(kn));
- if (inode && (inode->i_state & I_NEW))
- kernfs_init_inode(kn, inode);
- return inode;
- }
- /*
- * The kernfs_node serves as both an inode and a directory entry for
- * kernfs. To prevent the kernfs inode numbers from being freed
- * prematurely we take a reference to kernfs_node from the kernfs inode. A
- * super_operations.evict_inode() implementation is needed to drop that
- * reference upon inode destruction.
- */
- void kernfs_evict_inode(struct inode *inode)
- {
- struct kernfs_node *kn = inode->i_private;
- truncate_inode_pages_final(&inode->i_data);
- clear_inode(inode);
- kernfs_put(kn);
- }
- int kernfs_iop_permission(struct inode *inode, int mask)
- {
- struct kernfs_node *kn;
- if (mask & MAY_NOT_BLOCK)
- return -ECHILD;
- kn = inode->i_private;
- mutex_lock(&kernfs_mutex);
- kernfs_refresh_inode(kn, inode);
- mutex_unlock(&kernfs_mutex);
- return generic_permission(inode, mask);
- }
- int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
- void *value, size_t size)
- {
- struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
- if (!attrs)
- return -ENODATA;
- return simple_xattr_get(&attrs->xattrs, name, value, size);
- }
- int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
- const void *value, size_t size, int flags)
- {
- struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
- if (!attrs)
- return -ENOMEM;
- return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL);
- }
- static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
- struct dentry *unused, struct inode *inode,
- const char *suffix, void *value, size_t size,
- int flags)
- {
- const char *name = xattr_full_name(handler, suffix);
- struct kernfs_node *kn = inode->i_private;
- return kernfs_xattr_get(kn, name, value, size);
- }
- static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
- struct dentry *unused, struct inode *inode,
- const char *suffix, const void *value,
- size_t size, int flags)
- {
- const char *name = xattr_full_name(handler, suffix);
- struct kernfs_node *kn = inode->i_private;
- return kernfs_xattr_set(kn, name, value, size, flags);
- }
- static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
- const char *full_name,
- struct simple_xattrs *xattrs,
- const void *value, size_t size, int flags)
- {
- atomic_t *sz = &kn->iattr->user_xattr_size;
- atomic_t *nr = &kn->iattr->nr_user_xattrs;
- ssize_t removed_size;
- int ret;
- if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
- ret = -ENOSPC;
- goto dec_count_out;
- }
- if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
- ret = -ENOSPC;
- goto dec_size_out;
- }
- ret = simple_xattr_set(xattrs, full_name, value, size, flags,
- &removed_size);
- if (!ret && removed_size >= 0)
- size = removed_size;
- else if (!ret)
- return 0;
- dec_size_out:
- atomic_sub(size, sz);
- dec_count_out:
- atomic_dec(nr);
- return ret;
- }
- static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
- const char *full_name,
- struct simple_xattrs *xattrs,
- const void *value, size_t size, int flags)
- {
- atomic_t *sz = &kn->iattr->user_xattr_size;
- atomic_t *nr = &kn->iattr->nr_user_xattrs;
- ssize_t removed_size;
- int ret;
- ret = simple_xattr_set(xattrs, full_name, value, size, flags,
- &removed_size);
- if (removed_size >= 0) {
- atomic_sub(removed_size, sz);
- atomic_dec(nr);
- }
- return ret;
- }
- static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
- struct dentry *unused, struct inode *inode,
- const char *suffix, const void *value,
- size_t size, int flags)
- {
- const char *full_name = xattr_full_name(handler, suffix);
- struct kernfs_node *kn = inode->i_private;
- struct kernfs_iattrs *attrs;
- if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
- return -EOPNOTSUPP;
- attrs = kernfs_iattrs(kn);
- if (!attrs)
- return -ENOMEM;
- if (value)
- return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
- value, size, flags);
- else
- return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
- value, size, flags);
- }
- static const struct xattr_handler kernfs_trusted_xattr_handler = {
- .prefix = XATTR_TRUSTED_PREFIX,
- .get = kernfs_vfs_xattr_get,
- .set = kernfs_vfs_xattr_set,
- };
- static const struct xattr_handler kernfs_security_xattr_handler = {
- .prefix = XATTR_SECURITY_PREFIX,
- .get = kernfs_vfs_xattr_get,
- .set = kernfs_vfs_xattr_set,
- };
- static const struct xattr_handler kernfs_user_xattr_handler = {
- .prefix = XATTR_USER_PREFIX,
- .get = kernfs_vfs_xattr_get,
- .set = kernfs_vfs_user_xattr_set,
- };
- const struct xattr_handler *kernfs_xattr_handlers[] = {
- &kernfs_trusted_xattr_handler,
- &kernfs_security_xattr_handler,
- &kernfs_user_xattr_handler,
- NULL
- };
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