fs/ext4/acl.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * linux/fs/ext4/acl.c
  *
  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
  */

 #include <linux/quotaops.h>
 #include "ext4_jbd2.h"
 #include "ext4.h"
 #include "xattr.h"
 #include "acl.h"

 /*
  * Convert from filesystem to in-memory representation.
  */
 static struct posix_acl *
 ext4_acl_from_disk(const void *value, size_t size)
 {
 	const char *end = (char *)value + size;
 	int n, count;
 	struct posix_acl *acl;

 	if (!value)
 		return NULL;
 	if (size < sizeof(ext4_acl_header))
 		 return ERR_PTR(-EINVAL);
 	if (((ext4_acl_header *)value)->a_version !=
 	    cpu_to_le32(EXT4_ACL_VERSION))
 		return ERR_PTR(-EINVAL);
 	value = (char *)value + sizeof(ext4_acl_header);
 	count = ext4_acl_count(size);
 	if (count < 0)
 		return ERR_PTR(-EINVAL);
 	if (count == 0)
 		return NULL;
 	acl = posix_acl_alloc(count, GFP_NOFS);
 	if (!acl)
 		return ERR_PTR(-ENOMEM);
 	for (n = 0; n < count; n++) {
 		ext4_acl_entry *entry =
 			(ext4_acl_entry *)value;
 		if ((char *)value + sizeof(ext4_acl_entry_short) > end)
 			goto fail;
 		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
 		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);

 		switch (acl->a_entries[n].e_tag) {
 		case ACL_USER_OBJ:
 		case ACL_GROUP_OBJ:
 		case ACL_MASK:
 		case ACL_OTHER:
 			value = (char *)value +
 				sizeof(ext4_acl_entry_short);
 			break;

 		case ACL_USER:
 			value = (char *)value + sizeof(ext4_acl_entry);
 			if ((char *)value > end)
 				goto fail;
 			acl->a_entries[n].e_uid =
 				make_kuid(&init_user_ns,
 					  le32_to_cpu(entry->e_id));
 			break;
 		case ACL_GROUP:
 			value = (char *)value + sizeof(ext4_acl_entry);
 			if ((char *)value > end)
 				goto fail;
 			acl->a_entries[n].e_gid =
 				make_kgid(&init_user_ns,
 					  le32_to_cpu(entry->e_id));
 			break;

 		default:
 			goto fail;
 		}
 	}
 	if (value != end)
 		goto fail;
 	return acl;

 fail:
 	posix_acl_release(acl);
 	return ERR_PTR(-EINVAL);
 }

 /*
  * Convert from in-memory to filesystem representation.
  */
 static void *
 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
 {
 	ext4_acl_header *ext_acl;
 	char *e;
 	size_t n;

 	*size = ext4_acl_size(acl->a_count);
 	ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
 			sizeof(ext4_acl_entry), GFP_NOFS);
 	if (!ext_acl)
 		return ERR_PTR(-ENOMEM);
 	ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
 	e = (char *)ext_acl + sizeof(ext4_acl_header);
 	for (n = 0; n < acl->a_count; n++) {
 		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 		ext4_acl_entry *entry = (ext4_acl_entry *)e;
 		entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 		entry->e_perm = cpu_to_le16(acl_e->e_perm);
 		switch (acl_e->e_tag) {
 		case ACL_USER:
 			entry->e_id = cpu_to_le32(
 				from_kuid(&init_user_ns, acl_e->e_uid));
 			e += sizeof(ext4_acl_entry);
 			break;
 		case ACL_GROUP:
 			entry->e_id = cpu_to_le32(
 				from_kgid(&init_user_ns, acl_e->e_gid));
 			e += sizeof(ext4_acl_entry);
 			break;

 		case ACL_USER_OBJ:
 		case ACL_GROUP_OBJ:
 		case ACL_MASK:
 		case ACL_OTHER:
 			e += sizeof(ext4_acl_entry_short);
 			break;

 		default:
 			goto fail;
 		}
 	}
 	return (char *)ext_acl;

 fail:
 	kfree(ext_acl);
 	return ERR_PTR(-EINVAL);
 }

 /*
  * Inode operation get_posix_acl().
  *
  * inode->i_mutex: don't care
  */
 struct posix_acl *
 ext4_get_acl(struct inode *inode, int type, bool rcu)
 {
 	int name_index;
 	char *value = NULL;
 	struct posix_acl *acl;
 	int retval;

 	if (rcu)
 		return ERR_PTR(-ECHILD);

 	switch (type) {
 	case ACL_TYPE_ACCESS:
 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 		break;
 	case ACL_TYPE_DEFAULT:
 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 		break;
 	default:
 		BUG();
 	}
 	retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 	if (retval > 0) {
 		value = kmalloc(retval, GFP_NOFS);
 		if (!value)
 			return ERR_PTR(-ENOMEM);
 		retval = ext4_xattr_get(inode, name_index, "", value, retval);
 	}
 	if (retval > 0)
 		acl = ext4_acl_from_disk(value, retval);
 	else if (retval == -ENODATA || retval == -ENOSYS)
 		acl = NULL;
 	else
 		acl = ERR_PTR(retval);
 	kfree(value);

 	return acl;
 }

 /*
  * Set the access or default ACL of an inode.
  *
  * inode->i_mutex: down unless called from ext4_new_inode
  */
 static int
 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 	     struct posix_acl *acl, int xattr_flags)
 {
 	int name_index;
 	void *value = NULL;
 	size_t size = 0;
 	int error;

 	switch (type) {
 	case ACL_TYPE_ACCESS:
 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 		break;

 	case ACL_TYPE_DEFAULT:
 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 		if (!S_ISDIR(inode->i_mode))
 			return acl ? -EACCES : 0;
 		break;

 	default:
 		return -EINVAL;
 	}
 	if (acl) {
 		value = ext4_acl_to_disk(acl, &size);
 		if (IS_ERR(value))
 			return (int)PTR_ERR(value);
 	}

 	error = ext4_xattr_set_handle(handle, inode, name_index, "",
 				      value, size, xattr_flags);

 	kfree(value);
 	if (!error)
 		set_cached_acl(inode, type, acl);

 	return error;
 }

 int
 ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 	     struct posix_acl *acl, int type)
 {
 	handle_t *handle;
 	int error, credits, retries = 0;
 	size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
 	umode_t mode = inode->i_mode;
 	int update_mode = 0;

 	error = dquot_initialize(inode);
 	if (error)
 		return error;
 retry:
 	error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
 				       &credits);
 	if (error)
 		return error;

 	handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
 	if (IS_ERR(handle))
 		return PTR_ERR(handle);
 	ext4_fc_start_update(inode);

 	if ((type == ACL_TYPE_ACCESS) && acl) {
 		error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl);
 		if (error)
 			goto out_stop;
 		if (mode != inode->i_mode)
 			update_mode = 1;
 	}

 	error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
 	if (!error && update_mode) {
 		inode->i_mode = mode;
 		inode->i_ctime = current_time(inode);
 		error = ext4_mark_inode_dirty(handle, inode);
 	}
 out_stop:
 	ext4_journal_stop(handle);
 	ext4_fc_stop_update(inode);
 	if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 		goto retry;
 	return error;
 }

 /*
  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
  *
  * dir->i_mutex: down
  * inode->i_mutex: up (access to inode is still exclusive)
  */
 int
 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 {
 	struct posix_acl *default_acl, *acl;
 	int error;

 	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 	if (error)
 		return error;

 	if (default_acl) {
 		error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 				       default_acl, XATTR_CREATE);
 		posix_acl_release(default_acl);
 	} else {
 		inode->i_default_acl = NULL;
 	}
 	if (acl) {
 		if (!error)
 			error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
 					       acl, XATTR_CREATE);
 		posix_acl_release(acl);
 	} else {
 		inode->i_acl = NULL;
 	}
 	return error;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* linux/fs/ext4/acl.c
	*
	* Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
	*/

	#include <linux/quotaops.h>
	#include "ext4_jbd2.h"
	#include "ext4.h"
	#include "xattr.h"
	#include "acl.h"

	/*
	* Convert from filesystem to in-memory representation.
	*/
	static struct posix_acl *
	ext4_acl_from_disk(const void *value, size_t size)
	{
	const char end = (char )value + size;
	int n, count;
	struct posix_acl *acl;

	if (!value)
	return NULL;
	if (size < sizeof(ext4_acl_header))
	return ERR_PTR(-EINVAL);
	if (((ext4_acl_header *)value)->a_version !=
	cpu_to_le32(EXT4_ACL_VERSION))
	return ERR_PTR(-EINVAL);
	value = (char *)value + sizeof(ext4_acl_header);
	count = ext4_acl_count(size);
	if (count < 0)
	return ERR_PTR(-EINVAL);
	if (count == 0)
	return NULL;
	acl = posix_acl_alloc(count, GFP_NOFS);
	if (!acl)
	return ERR_PTR(-ENOMEM);
	for (n = 0; n < count; n++) {
	ext4_acl_entry *entry =
	(ext4_acl_entry *)value;
	if ((char *)value + sizeof(ext4_acl_entry_short) > end)
	goto fail;
	acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
	acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);

	switch (acl->a_entries[n].e_tag) {
	case ACL_USER_OBJ:
	case ACL_GROUP_OBJ:
	case ACL_MASK:
	case ACL_OTHER:
	value = (char *)value +
	sizeof(ext4_acl_entry_short);
	break;

	case ACL_USER:
	value = (char *)value + sizeof(ext4_acl_entry);
	if ((char *)value > end)
	goto fail;
	acl->a_entries[n].e_uid =
	make_kuid(&init_user_ns,
	le32_to_cpu(entry->e_id));
	break;
	case ACL_GROUP:
	value = (char *)value + sizeof(ext4_acl_entry);
	if ((char *)value > end)
	goto fail;
	acl->a_entries[n].e_gid =
	make_kgid(&init_user_ns,
	le32_to_cpu(entry->e_id));
	break;

	default:
	goto fail;
	}
	}
	if (value != end)
	goto fail;
	return acl;

	fail:
	posix_acl_release(acl);
	return ERR_PTR(-EINVAL);
	}

	/*
	* Convert from in-memory to filesystem representation.
	*/
	static void *
	ext4_acl_to_disk(const struct posix_acl acl, size_t size)
	{
	ext4_acl_header *ext_acl;
	char *e;
	size_t n;

	*size = ext4_acl_size(acl->a_count);
	ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
	sizeof(ext4_acl_entry), GFP_NOFS);
	if (!ext_acl)
	return ERR_PTR(-ENOMEM);
	ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
	e = (char *)ext_acl + sizeof(ext4_acl_header);
	for (n = 0; n < acl->a_count; n++) {
	const struct posix_acl_entry *acl_e = &acl->a_entries[n];
	ext4_acl_entry entry = (ext4_acl_entry )e;
	entry->e_tag = cpu_to_le16(acl_e->e_tag);
	entry->e_perm = cpu_to_le16(acl_e->e_perm);
	switch (acl_e->e_tag) {
	case ACL_USER:
	entry->e_id = cpu_to_le32(
	from_kuid(&init_user_ns, acl_e->e_uid));
	e += sizeof(ext4_acl_entry);
	break;
	case ACL_GROUP:
	entry->e_id = cpu_to_le32(
	from_kgid(&init_user_ns, acl_e->e_gid));
	e += sizeof(ext4_acl_entry);
	break;

	case ACL_USER_OBJ:
	case ACL_GROUP_OBJ:
	case ACL_MASK:
	case ACL_OTHER:
	e += sizeof(ext4_acl_entry_short);
	break;

	default:
	goto fail;
	}
	}
	return (char *)ext_acl;

	fail:
	kfree(ext_acl);
	return ERR_PTR(-EINVAL);
	}

	/*
	* Inode operation get_posix_acl().
	*
	* inode->i_mutex: don't care
	*/
	struct posix_acl *
	ext4_get_acl(struct inode *inode, int type, bool rcu)
	{
	int name_index;
	char *value = NULL;
	struct posix_acl *acl;
	int retval;

	if (rcu)
	return ERR_PTR(-ECHILD);

	switch (type) {
	case ACL_TYPE_ACCESS:
	name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
	break;
	case ACL_TYPE_DEFAULT:
	name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
	break;
	default:
	BUG();
	}
	retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
	if (retval > 0) {
	value = kmalloc(retval, GFP_NOFS);
	if (!value)
	return ERR_PTR(-ENOMEM);
	retval = ext4_xattr_get(inode, name_index, "", value, retval);
	}
	if (retval > 0)
	acl = ext4_acl_from_disk(value, retval);
	else if (retval == -ENODATA \|\| retval == -ENOSYS)
	acl = NULL;
	else
	acl = ERR_PTR(retval);
	kfree(value);

	return acl;
	}

	/*
	* Set the access or default ACL of an inode.
	*
	* inode->i_mutex: down unless called from ext4_new_inode
	*/
	static int
	__ext4_set_acl(handle_t handle, struct inode inode, int type,
	struct posix_acl *acl, int xattr_flags)
	{
	int name_index;
	void *value = NULL;
	size_t size = 0;
	int error;

	switch (type) {
	case ACL_TYPE_ACCESS:
	name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
	break;

	case ACL_TYPE_DEFAULT:
	name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
	if (!S_ISDIR(inode->i_mode))
	return acl ? -EACCES : 0;
	break;

	default:
	return -EINVAL;
	}
	if (acl) {
	value = ext4_acl_to_disk(acl, &size);
	if (IS_ERR(value))
	return (int)PTR_ERR(value);
	}

	error = ext4_xattr_set_handle(handle, inode, name_index, "",
	value, size, xattr_flags);

	kfree(value);
	if (!error)
	set_cached_acl(inode, type, acl);

	return error;
	}

	int
	ext4_set_acl(struct user_namespace mnt_userns, struct inode inode,
	struct posix_acl *acl, int type)
	{
	handle_t *handle;
	int error, credits, retries = 0;
	size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
	umode_t mode = inode->i_mode;
	int update_mode = 0;

	error = dquot_initialize(inode);
	if (error)
	return error;
	retry:
	error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
	&credits);
	if (error)
	return error;

	handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
	if (IS_ERR(handle))
	return PTR_ERR(handle);
	ext4_fc_start_update(inode);

	if ((type == ACL_TYPE_ACCESS) && acl) {
	error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl);
	if (error)
	goto out_stop;
	if (mode != inode->i_mode)
	update_mode = 1;
	}

	error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
	if (!error && update_mode) {
	inode->i_mode = mode;
	inode->i_ctime = current_time(inode);
	error = ext4_mark_inode_dirty(handle, inode);
	}
	out_stop:
	ext4_journal_stop(handle);
	ext4_fc_stop_update(inode);
	if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
	goto retry;
	return error;
	}

	/*
	* Initialize the ACLs of a new inode. Called from ext4_new_inode.
	*
	* dir->i_mutex: down
	* inode->i_mutex: up (access to inode is still exclusive)
	*/
	int
	ext4_init_acl(handle_t handle, struct inode inode, struct inode *dir)
	{
	struct posix_acl default_acl, acl;
	int error;

	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
	if (error)
	return error;

	if (default_acl) {
	error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
	default_acl, XATTR_CREATE);
	posix_acl_release(default_acl);
	} else {
	inode->i_default_acl = NULL;
	}
	if (acl) {
	if (!error)
	error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
	acl, XATTR_CREATE);
	posix_acl_release(acl);
	} else {
	inode->i_acl = NULL;
	}
	return error;
	}