fs/kernfs/inode.c - kernel/msm-4.19 - Gitiles

 /*
  * 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>
  *
  * This file is released under the GPLv2.
  */

 #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 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,
 	.removexattr	= sysfs_removexattr,
 	.getxattr	= sysfs_getxattr,
 	.listxattr	= sysfs_listxattr,
 };

 void __init sysfs_inode_init(void)
 {
 	if (bdi_init(&sysfs_backing_dev_info))
 		panic("failed to init sysfs_backing_dev_info");
 }

 static struct sysfs_inode_attrs *sysfs_inode_attrs(struct sysfs_dirent *sd)
 {
 	struct iattr *iattrs;

 	if (sd->s_iattr)
 		return sd->s_iattr;

 	sd->s_iattr = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
 	if (!sd->s_iattr)
 		return NULL;
 	iattrs = &sd->s_iattr->ia_iattr;

 	/* assign default attributes */
 	iattrs->ia_mode = sd->s_mode;
 	iattrs->ia_uid = GLOBAL_ROOT_UID;
 	iattrs->ia_gid = GLOBAL_ROOT_GID;
 	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;

 	simple_xattrs_init(&sd->s_iattr->xattrs);

 	return sd->s_iattr;
 }

 static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
 {
 	struct sysfs_inode_attrs *attrs;
 	struct iattr *iattrs;
 	unsigned int ia_valid = iattr->ia_valid;

 	attrs = sysfs_inode_attrs(sd);
 	if (!attrs)
 		return -ENOMEM;

 	iattrs = &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;
 }

 /**
  * kernfs_setattr - set iattr on a node
  * @sd: target node
  * @iattr: iattr to set
  *
  * Returns 0 on success, -errno on failure.
  */
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
 {
 	int ret;

 	mutex_lock(&sysfs_mutex);
 	ret = __kernfs_setattr(sd, iattr);
 	mutex_unlock(&sysfs_mutex);
 	return ret;
 }

 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;

 	mutex_lock(&sysfs_mutex);
 	error = inode_change_ok(inode, iattr);
 	if (error)
 		goto out;

 	error = __kernfs_setattr(sd, iattr);
 	if (error)
 		goto out;

 	/* this ignores size changes */
 	setattr_copy(inode, iattr);

 out:
 	mutex_unlock(&sysfs_mutex);
 	return error;
 }

 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
 			       u32 *secdata_len)
 {
 	struct sysfs_inode_attrs *attrs;
 	void *old_secdata;
 	size_t old_secdata_len;

 	attrs = sysfs_inode_attrs(sd);
 	if (!attrs)
 		return -ENOMEM;

 	old_secdata = attrs->ia_secdata;
 	old_secdata_len = attrs->ia_secdata_len;

 	attrs->ia_secdata = *secdata;
 	attrs->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;
 	struct sysfs_inode_attrs *attrs;
 	void *secdata;
 	int error;
 	u32 secdata_len = 0;

 	attrs = sysfs_inode_attrs(sd);
 	if (!attrs)
 		return -ENOMEM;

 	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)
 			return error;
 		error = security_inode_getsecctx(dentry->d_inode,
 						&secdata, &secdata_len);
 		if (error)
 			return error;

 		mutex_lock(&sysfs_mutex);
 		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
 		mutex_unlock(&sysfs_mutex);

 		if (secdata)
 			security_release_secctx(secdata, secdata_len);
 		return error;
 	} else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
 		return simple_xattr_set(&attrs->xattrs, name, value, size,
 					flags);
 	}

 	return -EINVAL;
 }

 int sysfs_removexattr(struct dentry *dentry, const char *name)
 {
 	struct sysfs_dirent *sd = dentry->d_fsdata;
 	struct sysfs_inode_attrs *attrs;

 	attrs = sysfs_inode_attrs(sd);
 	if (!attrs)
 		return -ENOMEM;

 	return simple_xattr_remove(&attrs->xattrs, name);
 }

 ssize_t sysfs_getxattr(struct dentry *dentry, const char *name, void *buf,
 		       size_t size)
 {
 	struct sysfs_dirent *sd = dentry->d_fsdata;
 	struct sysfs_inode_attrs *attrs;

 	attrs = sysfs_inode_attrs(sd);
 	if (!attrs)
 		return -ENOMEM;

 	return simple_xattr_get(&attrs->xattrs, name, buf, size);
 }

 ssize_t sysfs_listxattr(struct dentry *dentry, char *buf, size_t size)
 {
 	struct sysfs_dirent *sd = dentry->d_fsdata;
 	struct sysfs_inode_attrs *attrs;

 	attrs = sysfs_inode_attrs(sd);
 	if (!attrs)
 		return -ENOMEM;

 	return simple_xattr_list(&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;
 }

 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 void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
 {
 	struct sysfs_inode_attrs *attrs = sd->s_iattr;

 	inode->i_mode = sd->s_mode;
 	if (attrs) {
 		/* sysfs_dirent has non-default attributes
 		 * get them from persistent copy in sysfs_dirent
 		 */
 		set_inode_attr(inode, &attrs->ia_iattr);
 		security_inode_notifysecctx(inode, attrs->ia_secdata,
 					    attrs->ia_secdata_len);
 	}

 	if (sysfs_type(sd) == SYSFS_DIR)
 		set_nlink(inode, sd->s_dir.subdirs + 2);
 }

 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)
 {
 	kernfs_get(sd);
 	inode->i_private = 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 = sd->s_attr.size;
 		inode->i_fop = &kernfs_file_operations;
 		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
  *	@sb: super block
  *	@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 super_block *sb, struct sysfs_dirent *sd)
 {
 	struct inode *inode;

 	inode = iget_locked(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.evict_inode() implementation is needed to drop that
  * reference upon inode destruction.
  */
 void sysfs_evict_inode(struct inode *inode)
 {
 	struct sysfs_dirent *sd  = inode->i_private;

 	truncate_inode_pages(&inode->i_data, 0);
 	clear_inode(inode);
 	kernfs_put(sd);
 }

 int sysfs_permission(struct inode *inode, int mask)
 {
 	struct sysfs_dirent *sd;

 	if (mask & MAY_NOT_BLOCK)
 		return -ECHILD;

 	sd = inode->i_private;

 	mutex_lock(&sysfs_mutex);
 	sysfs_refresh_inode(sd, inode);
 	mutex_unlock(&sysfs_mutex);

 	return generic_permission(inode, mask);
 }
	/*
	* 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>
	*
	* This file is released under the GPLv2.
	*/

	#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 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,
	.removexattr = sysfs_removexattr,
	.getxattr = sysfs_getxattr,
	.listxattr = sysfs_listxattr,
	};

	void __init sysfs_inode_init(void)
	{
	if (bdi_init(&sysfs_backing_dev_info))
	panic("failed to init sysfs_backing_dev_info");
	}

	static struct sysfs_inode_attrs sysfs_inode_attrs(struct sysfs_dirent sd)
	{
	struct iattr *iattrs;

	if (sd->s_iattr)
	return sd->s_iattr;

	sd->s_iattr = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
	if (!sd->s_iattr)
	return NULL;
	iattrs = &sd->s_iattr->ia_iattr;

	/* assign default attributes */
	iattrs->ia_mode = sd->s_mode;
	iattrs->ia_uid = GLOBAL_ROOT_UID;
	iattrs->ia_gid = GLOBAL_ROOT_GID;
	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;

	simple_xattrs_init(&sd->s_iattr->xattrs);

	return sd->s_iattr;
	}

	static int __kernfs_setattr(struct sysfs_dirent sd, const struct iattr iattr)
	{
	struct sysfs_inode_attrs *attrs;
	struct iattr *iattrs;
	unsigned int ia_valid = iattr->ia_valid;

	attrs = sysfs_inode_attrs(sd);
	if (!attrs)
	return -ENOMEM;

	iattrs = &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;
	}

	/**
	* kernfs_setattr - set iattr on a node
	* @sd: target node
	* @iattr: iattr to set
	*
	* Returns 0 on success, -errno on failure.
	*/
	int kernfs_setattr(struct sysfs_dirent sd, const struct iattr iattr)
	{
	int ret;

	mutex_lock(&sysfs_mutex);
	ret = __kernfs_setattr(sd, iattr);
	mutex_unlock(&sysfs_mutex);
	return ret;
	}

	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;

	mutex_lock(&sysfs_mutex);
	error = inode_change_ok(inode, iattr);
	if (error)
	goto out;

	error = __kernfs_setattr(sd, iattr);
	if (error)
	goto out;

	/* this ignores size changes */
	setattr_copy(inode, iattr);

	out:
	mutex_unlock(&sysfs_mutex);
	return error;
	}

	static int sysfs_sd_setsecdata(struct sysfs_dirent sd, void *secdata,
	u32 *secdata_len)
	{
	struct sysfs_inode_attrs *attrs;
	void *old_secdata;
	size_t old_secdata_len;

	attrs = sysfs_inode_attrs(sd);
	if (!attrs)
	return -ENOMEM;

	old_secdata = attrs->ia_secdata;
	old_secdata_len = attrs->ia_secdata_len;

	attrs->ia_secdata = *secdata;
	attrs->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;
	struct sysfs_inode_attrs *attrs;
	void *secdata;
	int error;
	u32 secdata_len = 0;

	attrs = sysfs_inode_attrs(sd);
	if (!attrs)
	return -ENOMEM;

	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)
	return error;
	error = security_inode_getsecctx(dentry->d_inode,
	&secdata, &secdata_len);
	if (error)
	return error;

	mutex_lock(&sysfs_mutex);
	error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
	mutex_unlock(&sysfs_mutex);

	if (secdata)
	security_release_secctx(secdata, secdata_len);
	return error;
	} else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
	return simple_xattr_set(&attrs->xattrs, name, value, size,
	flags);
	}

	return -EINVAL;
	}

	int sysfs_removexattr(struct dentry dentry, const char name)
	{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	struct sysfs_inode_attrs *attrs;

	attrs = sysfs_inode_attrs(sd);
	if (!attrs)
	return -ENOMEM;

	return simple_xattr_remove(&attrs->xattrs, name);
	}

	ssize_t sysfs_getxattr(struct dentry dentry, const char name, void *buf,
	size_t size)
	{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	struct sysfs_inode_attrs *attrs;

	attrs = sysfs_inode_attrs(sd);
	if (!attrs)
	return -ENOMEM;

	return simple_xattr_get(&attrs->xattrs, name, buf, size);
	}

	ssize_t sysfs_listxattr(struct dentry dentry, char buf, size_t size)
	{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	struct sysfs_inode_attrs *attrs;

	attrs = sysfs_inode_attrs(sd);
	if (!attrs)
	return -ENOMEM;

	return simple_xattr_list(&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;
	}

	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 void sysfs_refresh_inode(struct sysfs_dirent sd, struct inode inode)
	{
	struct sysfs_inode_attrs *attrs = sd->s_iattr;

	inode->i_mode = sd->s_mode;
	if (attrs) {
	/* sysfs_dirent has non-default attributes
	* get them from persistent copy in sysfs_dirent
	*/
	set_inode_attr(inode, &attrs->ia_iattr);
	security_inode_notifysecctx(inode, attrs->ia_secdata,
	attrs->ia_secdata_len);
	}

	if (sysfs_type(sd) == SYSFS_DIR)
	set_nlink(inode, sd->s_dir.subdirs + 2);
	}

	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)
	{
	kernfs_get(sd);
	inode->i_private = 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 = sd->s_attr.size;
	inode->i_fop = &kernfs_file_operations;
	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
	* @sb: super block
	* @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 super_block sb, struct sysfs_dirent *sd)
	{
	struct inode *inode;

	inode = iget_locked(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.evict_inode() implementation is needed to drop that
	* reference upon inode destruction.
	*/
	void sysfs_evict_inode(struct inode *inode)
	{
	struct sysfs_dirent *sd = inode->i_private;

	truncate_inode_pages(&inode->i_data, 0);
	clear_inode(inode);
	kernfs_put(sd);
	}

	int sysfs_permission(struct inode *inode, int mask)
	{
	struct sysfs_dirent *sd;

	if (mask & MAY_NOT_BLOCK)
	return -ECHILD;

	sd = inode->i_private;

	mutex_lock(&sysfs_mutex);
	sysfs_refresh_inode(sd, inode);
	mutex_unlock(&sysfs_mutex);

	return generic_permission(inode, mask);
	}