1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Red Hat.  All rights reserved.
4 */
5
6#include <linux/fs.h>
7#include <linux/string.h>
8#include <linux/xattr.h>
9#include <linux/posix_acl_xattr.h>
10#include <linux/posix_acl.h>
11#include <linux/sched.h>
12#include <linux/sched/mm.h>
13#include <linux/slab.h>
14#include "ctree.h"
15#include "xattr.h"
16#include "acl.h"
17
18struct posix_acl *btrfs_get_acl(struct inode *inode, int type, bool rcu)
19{
20	int size;
21	const char *name;
22	char *value = NULL;
23	struct posix_acl *acl;
24
25	if (rcu)
26		return ERR_PTR(-ECHILD);
27
28	switch (type) {
29	case ACL_TYPE_ACCESS:
30		name = XATTR_NAME_POSIX_ACL_ACCESS;
31		break;
32	case ACL_TYPE_DEFAULT:
33		name = XATTR_NAME_POSIX_ACL_DEFAULT;
34		break;
35	default:
36		return ERR_PTR(-EINVAL);
37	}
38
39	size = btrfs_getxattr(inode, name, NULL, 0);
40	if (size > 0) {
41		value = kzalloc(size, GFP_KERNEL);
42		if (!value)
43			return ERR_PTR(-ENOMEM);
44		size = btrfs_getxattr(inode, name, value, size);
45	}
46	if (size > 0)
47		acl = posix_acl_from_xattr(&init_user_ns, value, size);
48	else if (size == -ENODATA || size == 0)
49		acl = NULL;
50	else
51		acl = ERR_PTR(size);
52	kfree(value);
53
54	return acl;
55}
56
57int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,
58		    struct posix_acl *acl, int type)
59{
60	int ret, size = 0;
61	const char *name;
62	char *value = NULL;
63
64	switch (type) {
65	case ACL_TYPE_ACCESS:
66		name = XATTR_NAME_POSIX_ACL_ACCESS;
67		break;
68	case ACL_TYPE_DEFAULT:
69		if (!S_ISDIR(inode->i_mode))
70			return acl ? -EINVAL : 0;
71		name = XATTR_NAME_POSIX_ACL_DEFAULT;
72		break;
73	default:
74		return -EINVAL;
75	}
76
77	if (acl) {
78		unsigned int nofs_flag;
79
80		size = posix_acl_xattr_size(acl->a_count);
81		/*
82		 * We're holding a transaction handle, so use a NOFS memory
83		 * allocation context to avoid deadlock if reclaim happens.
84		 */
85		nofs_flag = memalloc_nofs_save();
86		value = kmalloc(size, GFP_KERNEL);
87		memalloc_nofs_restore(nofs_flag);
88		if (!value) {
89			ret = -ENOMEM;
90			goto out;
91		}
92
93		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
94		if (ret < 0)
95			goto out;
96	}
97
98	if (trans)
99		ret = btrfs_setxattr(trans, inode, name, value, size, 0);
100	else
101		ret = btrfs_setxattr_trans(inode, name, value, size, 0);
102
103out:
104	kfree(value);
105
106	if (!ret)
107		set_cached_acl(inode, type, acl);
108
109	return ret;
110}
111
112int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
113		  struct posix_acl *acl, int type)
114{
115	int ret;
116	struct inode *inode = d_inode(dentry);
117	umode_t old_mode = inode->i_mode;
118
119	if (type == ACL_TYPE_ACCESS && acl) {
120		ret = posix_acl_update_mode(idmap, inode,
121					    &inode->i_mode, &acl);
122		if (ret)
123			return ret;
124	}
125	ret = __btrfs_set_acl(NULL, inode, acl, type);
126	if (ret)
127		inode->i_mode = old_mode;
128	return ret;
129}
130