Initial import

1 files changed, 905 insertions, 0 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
new file mode 100644
index 000000000..84bb65b83
--- /dev/null
+++ b/fs/posix_acl.c
@@ -0,0 +1,905 @@
+/*
+ * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
+ *
+ * Fixes from William Schumacher incorporated on 15 March 2001.
+ *    (Reported by Charles Bertsch, <CBertsch@microtest.com>).
+ */
+
+/*
+ *  This file contains generic functions for manipulating
+ *  POSIX 1003.1e draft standard 17 ACLs.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/atomic.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/xattr.h>
+#include <linux/export.h>
+#include <linux/user_namespace.h>
+
+struct posix_acl **acl_by_type(struct inode *inode, int type)
+{
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		return &inode->i_acl;
+	case ACL_TYPE_DEFAULT:
+		return &inode->i_default_acl;
+	default:
+		BUG();
+	}
+}
+EXPORT_SYMBOL(acl_by_type);
+
+struct posix_acl *get_cached_acl(struct inode *inode, int type)
+{
+	struct posix_acl **p = acl_by_type(inode, type);
+	struct posix_acl *acl = ACCESS_ONCE(*p);
+	if (acl) {
+		spin_lock(&inode->i_lock);
+		acl = *p;
+		if (acl != ACL_NOT_CACHED)
+			acl = posix_acl_dup(acl);
+		spin_unlock(&inode->i_lock);
+	}
+	return acl;
+}
+EXPORT_SYMBOL(get_cached_acl);
+
+struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
+{
+	return rcu_dereference(*acl_by_type(inode, type));
+}
+EXPORT_SYMBOL(get_cached_acl_rcu);
+
+void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
+{
+	struct posix_acl **p = acl_by_type(inode, type);
+	struct posix_acl *old;
+	spin_lock(&inode->i_lock);
+	old = *p;
+	rcu_assign_pointer(*p, posix_acl_dup(acl));
+	spin_unlock(&inode->i_lock);
+	if (old != ACL_NOT_CACHED)
+		posix_acl_release(old);
+}
+EXPORT_SYMBOL(set_cached_acl);
+
+void forget_cached_acl(struct inode *inode, int type)
+{
+	struct posix_acl **p = acl_by_type(inode, type);
+	struct posix_acl *old;
+	spin_lock(&inode->i_lock);
+	old = *p;
+	*p = ACL_NOT_CACHED;
+	spin_unlock(&inode->i_lock);
+	if (old != ACL_NOT_CACHED)
+		posix_acl_release(old);
+}
+EXPORT_SYMBOL(forget_cached_acl);
+
+void forget_all_cached_acls(struct inode *inode)
+{
+	struct posix_acl *old_access, *old_default;
+	spin_lock(&inode->i_lock);
+	old_access = inode->i_acl;
+	old_default = inode->i_default_acl;
+	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
+	spin_unlock(&inode->i_lock);
+	if (old_access != ACL_NOT_CACHED)
+		posix_acl_release(old_access);
+	if (old_default != ACL_NOT_CACHED)
+		posix_acl_release(old_default);
+}
+EXPORT_SYMBOL(forget_all_cached_acls);
+
+struct posix_acl *get_acl(struct inode *inode, int type)
+{
+	struct posix_acl *acl;
+
+	acl = get_cached_acl(inode, type);
+	if (acl != ACL_NOT_CACHED)
+		return acl;
+
+	if (!IS_POSIXACL(inode))
+		return NULL;
+
+	/*
+	 * A filesystem can force a ACL callback by just never filling the
+	 * ACL cache. But normally you'd fill the cache either at inode
+	 * instantiation time, or on the first ->get_acl call.
+	 *
+	 * If the filesystem doesn't have a get_acl() function at all, we'll
+	 * just create the negative cache entry.
+	 */
+	if (!inode->i_op->get_acl) {
+		set_cached_acl(inode, type, NULL);
+		return NULL;
+	}
+	return inode->i_op->get_acl(inode, type);
+}
+EXPORT_SYMBOL(get_acl);
+
+/*
+ * Init a fresh posix_acl
+ */
+void
+posix_acl_init(struct posix_acl *acl, int count)
+{
+	atomic_set(&acl->a_refcount, 1);
+	acl->a_count = count;
+}
+EXPORT_SYMBOL(posix_acl_init);
+
+/*
+ * Allocate a new ACL with the specified number of entries.
+ */
+struct posix_acl *
+posix_acl_alloc(int count, gfp_t flags)
+{
+	const size_t size = sizeof(struct posix_acl) +
+	                    count * sizeof(struct posix_acl_entry);
+	struct posix_acl *acl = kmalloc(size, flags);
+	if (acl)
+		posix_acl_init(acl, count);
+	return acl;
+}
+EXPORT_SYMBOL(posix_acl_alloc);
+
+/*
+ * Clone an ACL.
+ */
+static struct posix_acl *
+posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
+{
+	struct posix_acl *clone = NULL;
+
+	if (acl) {
+		int size = sizeof(struct posix_acl) + acl->a_count *
+		           sizeof(struct posix_acl_entry);
+		clone = kmemdup(acl, size, flags);
+		if (clone)
+			atomic_set(&clone->a_refcount, 1);
+	}
+	return clone;
+}
+
+/*
+ * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
+ */
+int
+posix_acl_valid(const struct posix_acl *acl)
+{
+	const struct posix_acl_entry *pa, *pe;
+	int state = ACL_USER_OBJ;
+	int needs_mask = 0;
+
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+		if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
+			return -EINVAL;
+		switch (pa->e_tag) {
+			case ACL_USER_OBJ:
+				if (state == ACL_USER_OBJ) {
+					state = ACL_USER;
+					break;
+				}
+				return -EINVAL;
+
+			case ACL_USER:
+				if (state != ACL_USER)
+					return -EINVAL;
+				if (!uid_valid(pa->e_uid))
+					return -EINVAL;
+				needs_mask = 1;
+				break;
+
+			case ACL_GROUP_OBJ:
+				if (state == ACL_USER) {
+					state = ACL_GROUP;
+					break;
+				}
+				return -EINVAL;
+
+			case ACL_GROUP:
+				if (state != ACL_GROUP)
+					return -EINVAL;
+				if (!gid_valid(pa->e_gid))
+					return -EINVAL;
+				needs_mask = 1;
+				break;
+
+			case ACL_MASK:
+				if (state != ACL_GROUP)
+					return -EINVAL;
+				state = ACL_OTHER;
+				break;
+
+			case ACL_OTHER:
+				if (state == ACL_OTHER ||
+				    (state == ACL_GROUP && !needs_mask)) {
+					state = 0;
+					break;
+				}
+				return -EINVAL;
+
+			default:
+				return -EINVAL;
+		}
+	}
+	if (state == 0)
+		return 0;
+	return -EINVAL;
+}
+EXPORT_SYMBOL(posix_acl_valid);
+
+/*
+ * Returns 0 if the acl can be exactly represented in the traditional
+ * file mode permission bits, or else 1. Returns -E... on error.
+ */
+int
+posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
+{
+	const struct posix_acl_entry *pa, *pe;
+	umode_t mode = 0;
+	int not_equiv = 0;
+
+	/*
+	 * A null ACL can always be presented as mode bits.
+	 */
+	if (!acl)
+		return 0;
+
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+		switch (pa->e_tag) {
+			case ACL_USER_OBJ:
+				mode |= (pa->e_perm & S_IRWXO) << 6;
+				break;
+			case ACL_GROUP_OBJ:
+				mode |= (pa->e_perm & S_IRWXO) << 3;
+				break;
+			case ACL_OTHER:
+				mode |= pa->e_perm & S_IRWXO;
+				break;
+			case ACL_MASK:
+				mode = (mode & ~S_IRWXG) |
+				       ((pa->e_perm & S_IRWXO) << 3);
+				not_equiv = 1;
+				break;
+			case ACL_USER:
+			case ACL_GROUP:
+				not_equiv = 1;
+				break;
+			default:
+				return -EINVAL;
+		}
+	}
+        if (mode_p)
+                *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
+        return not_equiv;
+}
+EXPORT_SYMBOL(posix_acl_equiv_mode);
+
+/*
+ * Create an ACL representing the file mode permission bits of an inode.
+ */
+struct posix_acl *
+posix_acl_from_mode(umode_t mode, gfp_t flags)
+{
+	struct posix_acl *acl = posix_acl_alloc(3, flags);
+	if (!acl)
+		return ERR_PTR(-ENOMEM);
+
+	acl->a_entries[0].e_tag  = ACL_USER_OBJ;
+	acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
+
+	acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
+	acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
+
+	acl->a_entries[2].e_tag  = ACL_OTHER;
+	acl->a_entries[2].e_perm = (mode & S_IRWXO);
+	return acl;
+}
+EXPORT_SYMBOL(posix_acl_from_mode);
+
+/*
+ * Return 0 if current is granted want access to the inode
+ * by the acl. Returns -E... otherwise.
+ */
+int
+posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
+{
+	const struct posix_acl_entry *pa, *pe, *mask_obj;
+	int found = 0;
+
+	want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
+
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+                switch(pa->e_tag) {
+                        case ACL_USER_OBJ:
+				/* (May have been checked already) */
+				if (uid_eq(inode->i_uid, current_fsuid()))
+                                        goto check_perm;
+                                break;
+                        case ACL_USER:
+				if (uid_eq(pa->e_uid, current_fsuid()))
+                                        goto mask;
+				break;
+                        case ACL_GROUP_OBJ:
+                                if (in_group_p(inode->i_gid)) {
+					found = 1;
+					if ((pa->e_perm & want) == want)
+						goto mask;
+                                }
+				break;
+                        case ACL_GROUP:
+				if (in_group_p(pa->e_gid)) {
+					found = 1;
+					if ((pa->e_perm & want) == want)
+						goto mask;
+                                }
+                                break;
+                        case ACL_MASK:
+                                break;
+                        case ACL_OTHER:
+				if (found)
+					return -EACCES;
+				else
+					goto check_perm;
+			default:
+				return -EIO;
+                }
+        }
+	return -EIO;
+
+mask:
+	for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
+		if (mask_obj->e_tag == ACL_MASK) {
+			if ((pa->e_perm & mask_obj->e_perm & want) == want)
+				return 0;
+			return -EACCES;
+		}
+	}
+
+check_perm:
+	if ((pa->e_perm & want) == want)
+		return 0;
+	return -EACCES;
+}
+
+/*
+ * Modify acl when creating a new inode. The caller must ensure the acl is
+ * only referenced once.
+ *
+ * mode_p initially must contain the mode parameter to the open() / creat()
+ * system calls. All permissions that are not granted by the acl are removed.
+ * The permissions in the acl are changed to reflect the mode_p parameter.
+ */
+static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
+{
+	struct posix_acl_entry *pa, *pe;
+	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
+	umode_t mode = *mode_p;
+	int not_equiv = 0;
+
+	/* assert(atomic_read(acl->a_refcount) == 1); */
+
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+                switch(pa->e_tag) {
+                        case ACL_USER_OBJ:
+				pa->e_perm &= (mode >> 6) | ~S_IRWXO;
+				mode &= (pa->e_perm << 6) | ~S_IRWXU;
+				break;
+
+			case ACL_USER:
+			case ACL_GROUP:
+				not_equiv = 1;
+				break;
+
+                        case ACL_GROUP_OBJ:
+				group_obj = pa;
+                                break;
+
+                        case ACL_OTHER:
+				pa->e_perm &= mode | ~S_IRWXO;
+				mode &= pa->e_perm | ~S_IRWXO;
+                                break;
+
+                        case ACL_MASK:
+				mask_obj = pa;
+				not_equiv = 1;
+                                break;
+
+			default:
+				return -EIO;
+                }
+        }
+
+	if (mask_obj) {
+		mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
+		mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
+	} else {
+		if (!group_obj)
+			return -EIO;
+		group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
+		mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
+	}
+
+	*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
+        return not_equiv;
+}
+
+/*
+ * Modify the ACL for the chmod syscall.
+ */
+static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
+{
+	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
+	struct posix_acl_entry *pa, *pe;
+
+	/* assert(atomic_read(acl->a_refcount) == 1); */
+
+	FOREACH_ACL_ENTRY(pa, acl, pe) {
+		switch(pa->e_tag) {
+			case ACL_USER_OBJ:
+				pa->e_perm = (mode & S_IRWXU) >> 6;
+				break;
+
+			case ACL_USER:
+			case ACL_GROUP:
+				break;
+
+			case ACL_GROUP_OBJ:
+				group_obj = pa;
+				break;
+
+			case ACL_MASK:
+				mask_obj = pa;
+				break;
+
+			case ACL_OTHER:
+				pa->e_perm = (mode & S_IRWXO);
+				break;
+
+			default:
+				return -EIO;
+		}
+	}
+
+	if (mask_obj) {
+		mask_obj->e_perm = (mode & S_IRWXG) >> 3;
+	} else {
+		if (!group_obj)
+			return -EIO;
+		group_obj->e_perm = (mode & S_IRWXG) >> 3;
+	}
+
+	return 0;
+}
+
+int
+__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
+{
+	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
+	int err = -ENOMEM;
+	if (clone) {
+		err = posix_acl_create_masq(clone, mode_p);
+		if (err < 0) {
+			posix_acl_release(clone);
+			clone = NULL;
+		}
+	}
+	posix_acl_release(*acl);
+	*acl = clone;
+	return err;
+}
+EXPORT_SYMBOL(__posix_acl_create);
+
+int
+__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
+{
+	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
+	int err = -ENOMEM;
+	if (clone) {
+		err = __posix_acl_chmod_masq(clone, mode);
+		if (err) {
+			posix_acl_release(clone);
+			clone = NULL;
+		}
+	}
+	posix_acl_release(*acl);
+	*acl = clone;
+	return err;
+}
+EXPORT_SYMBOL(__posix_acl_chmod);
+
+int
+posix_acl_chmod(struct inode *inode, umode_t mode)
+{
+	struct posix_acl *acl;
+	int ret = 0;
+
+	if (!IS_POSIXACL(inode))
+		return 0;
+	if (!inode->i_op->set_acl)
+		return -EOPNOTSUPP;
+
+	acl = get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR_OR_NULL(acl)) {
+		if (acl == ERR_PTR(-EOPNOTSUPP))
+			return 0;
+		return PTR_ERR(acl);
+	}
+
+	ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
+	if (ret)
+		return ret;
+	ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
+	posix_acl_release(acl);
+	return ret;
+}
+EXPORT_SYMBOL(posix_acl_chmod);
+
+int
+posix_acl_create(struct inode *dir, umode_t *mode,
+		struct posix_acl **default_acl, struct posix_acl **acl)
+{
+	struct posix_acl *p;
+	int ret;
+
+	if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
+		goto no_acl;
+
+	p = get_acl(dir, ACL_TYPE_DEFAULT);
+	if (IS_ERR(p)) {
+		if (p == ERR_PTR(-EOPNOTSUPP))
+			goto apply_umask;
+		return PTR_ERR(p);
+	}
+
+	if (!p)
+		goto apply_umask;
+
+	*acl = posix_acl_clone(p, GFP_NOFS);
+	if (!*acl)
+		goto no_mem;
+
+	ret = posix_acl_create_masq(*acl, mode);
+	if (ret < 0)
+		goto no_mem_clone;
+
+	if (ret == 0) {
+		posix_acl_release(*acl);
+		*acl = NULL;
+	}
+
+	if (!S_ISDIR(*mode)) {
+		posix_acl_release(p);
+		*default_acl = NULL;
+	} else {
+		*default_acl = p;
+	}
+	return 0;
+
+apply_umask:
+	*mode &= ~current_umask();
+no_acl:
+	*default_acl = NULL;
+	*acl = NULL;
+	return 0;
+
+no_mem_clone:
+	posix_acl_release(*acl);
+no_mem:
+	posix_acl_release(p);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(posix_acl_create);
+
+/*
+ * Fix up the uids and gids in posix acl extended attributes in place.
+ */
+static void posix_acl_fix_xattr_userns(
+	struct user_namespace *to, struct user_namespace *from,
+	void *value, size_t size)
+{
+	posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
+	posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
+	int count;
+	kuid_t uid;
+	kgid_t gid;
+
+	if (!value)
+		return;
+	if (size < sizeof(posix_acl_xattr_header))
+		return;
+	if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
+		return;
+
+	count = posix_acl_xattr_count(size);
+	if (count < 0)
+		return;
+	if (count == 0)
+		return;
+
+	for (end = entry + count; entry != end; entry++) {
+		switch(le16_to_cpu(entry->e_tag)) {
+		case ACL_USER:
+			uid = make_kuid(from, le32_to_cpu(entry->e_id));
+			entry->e_id = cpu_to_le32(from_kuid(to, uid));
+			break;
+		case ACL_GROUP:
+			gid = make_kgid(from, le32_to_cpu(entry->e_id));
+			entry->e_id = cpu_to_le32(from_kgid(to, gid));
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+void posix_acl_fix_xattr_from_user(void *value, size_t size)
+{
+	struct user_namespace *user_ns = current_user_ns();
+	if (user_ns == &init_user_ns)
+		return;
+	posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
+}
+
+void posix_acl_fix_xattr_to_user(void *value, size_t size)
+{
+	struct user_namespace *user_ns = current_user_ns();
+	if (user_ns == &init_user_ns)
+		return;
+	posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
+}
+
+/*
+ * Convert from extended attribute to in-memory representation.
+ */
+struct posix_acl *
+posix_acl_from_xattr(struct user_namespace *user_ns,
+		     const void *value, size_t size)
+{
+	posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
+	posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
+	int count;
+	struct posix_acl *acl;
+	struct posix_acl_entry *acl_e;
+
+	if (!value)
+		return NULL;
+	if (size < sizeof(posix_acl_xattr_header))
+		 return ERR_PTR(-EINVAL);
+	if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
+		return ERR_PTR(-EOPNOTSUPP);
+
+	count = posix_acl_xattr_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);
+	acl_e = acl->a_entries;
+	
+	for (end = entry + count; entry != end; acl_e++, entry++) {
+		acl_e->e_tag  = le16_to_cpu(entry->e_tag);
+		acl_e->e_perm = le16_to_cpu(entry->e_perm);
+
+		switch(acl_e->e_tag) {
+			case ACL_USER_OBJ:
+			case ACL_GROUP_OBJ:
+			case ACL_MASK:
+			case ACL_OTHER:
+				break;
+
+			case ACL_USER:
+				acl_e->e_uid =
+					make_kuid(user_ns,
+						  le32_to_cpu(entry->e_id));
+				if (!uid_valid(acl_e->e_uid))
+					goto fail;
+				break;
+			case ACL_GROUP:
+				acl_e->e_gid =
+					make_kgid(user_ns,
+						  le32_to_cpu(entry->e_id));
+				if (!gid_valid(acl_e->e_gid))
+					goto fail;
+				break;
+
+			default:
+				goto fail;
+		}
+	}
+	return acl;
+
+fail:
+	posix_acl_release(acl);
+	return ERR_PTR(-EINVAL);
+}
+EXPORT_SYMBOL (posix_acl_from_xattr);
+
+/*
+ * Convert from in-memory to extended attribute representation.
+ */
+int
+posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
+		   void *buffer, size_t size)
+{
+	posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
+	posix_acl_xattr_entry *ext_entry;
+	int real_size, n;
+
+	real_size = posix_acl_xattr_size(acl->a_count);
+	if (!buffer)
+		return real_size;
+	if (real_size > size)
+		return -ERANGE;
+
+	ext_entry = ext_acl->a_entries;
+	ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
+
+	for (n=0; n < acl->a_count; n++, ext_entry++) {
+		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
+		ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
+		ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
+		switch(acl_e->e_tag) {
+		case ACL_USER:
+			ext_entry->e_id =
+				cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
+			break;
+		case ACL_GROUP:
+			ext_entry->e_id =
+				cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
+			break;
+		default:
+			ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
+			break;
+		}
+	}
+	return real_size;
+}
+EXPORT_SYMBOL (posix_acl_to_xattr);
+
+static int
+posix_acl_xattr_get(struct dentry *dentry, const char *name,
+		void *value, size_t size, int type)
+{
+	struct posix_acl *acl;
+	int error;
+
+	if (!IS_POSIXACL(d_backing_inode(dentry)))
+		return -EOPNOTSUPP;
+	if (d_is_symlink(dentry))
+		return -EOPNOTSUPP;
+
+	acl = get_acl(d_backing_inode(dentry), type);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (acl == NULL)
+		return -ENODATA;
+
+	error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
+	posix_acl_release(acl);
+
+	return error;
+}
+
+static int
+posix_acl_xattr_set(struct dentry *dentry, const char *name,
+		const void *value, size_t size, int flags, int type)
+{
+	struct inode *inode = d_backing_inode(dentry);
+	struct posix_acl *acl = NULL;
+	int ret;
+
+	if (!IS_POSIXACL(inode))
+		return -EOPNOTSUPP;
+	if (!inode->i_op->set_acl)
+		return -EOPNOTSUPP;
+
+	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
+		return value ? -EACCES : 0;
+	if (!inode_owner_or_capable(inode))
+		return -EPERM;
+
+	if (value) {
+		acl = posix_acl_from_xattr(&init_user_ns, value, size);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+
+		if (acl) {
+			ret = posix_acl_valid(acl);
+			if (ret)
+				goto out;
+		}
+	}
+
+	ret = inode->i_op->set_acl(inode, acl, type);
+out:
+	posix_acl_release(acl);
+	return ret;
+}
+
+static size_t
+posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
+		const char *name, size_t name_len, int type)
+{
+	const char *xname;
+	size_t size;
+
+	if (!IS_POSIXACL(d_backing_inode(dentry)))
+		return -EOPNOTSUPP;
+	if (d_is_symlink(dentry))
+		return -EOPNOTSUPP;
+
+	if (type == ACL_TYPE_ACCESS)
+		xname = POSIX_ACL_XATTR_ACCESS;
+	else
+		xname = POSIX_ACL_XATTR_DEFAULT;
+
+	size = strlen(xname) + 1;
+	if (list && size <= list_size)
+		memcpy(list, xname, size);
+	return size;
+}
+
+const struct xattr_handler posix_acl_access_xattr_handler = {
+	.prefix = POSIX_ACL_XATTR_ACCESS,
+	.flags = ACL_TYPE_ACCESS,
+	.list = posix_acl_xattr_list,
+	.get = posix_acl_xattr_get,
+	.set = posix_acl_xattr_set,
+};
+EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
+
+const struct xattr_handler posix_acl_default_xattr_handler = {
+	.prefix = POSIX_ACL_XATTR_DEFAULT,
+	.flags = ACL_TYPE_DEFAULT,
+	.list = posix_acl_xattr_list,
+	.get = posix_acl_xattr_get,
+	.set = posix_acl_xattr_set,
+};
+EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
+
+int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	int error;
+
+	if (type == ACL_TYPE_ACCESS) {
+		error = posix_acl_equiv_mode(acl, &inode->i_mode);
+		if (error < 0)
+			return 0;
+		if (error == 0)
+			acl = NULL;
+	}
+
+	inode->i_ctime = CURRENT_TIME;
+	set_cached_acl(inode, type, acl);
+	return 0;
+}
+
+int simple_acl_create(struct inode *dir, struct inode *inode)
+{
+	struct posix_acl *default_acl, *acl;
+	int error;
+
+	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
+	if (error)
+		return error;
+
+	set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
+	set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
+
+	if (default_acl)
+		posix_acl_release(default_acl);
+	if (acl)
+		posix_acl_release(acl);
+	return 0;
+}