acl.c revision 4a8b34af
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
15#include "ctree.h"
16#include "btrfs_inode.h"
17#include "xattr.h"
18
19struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
20{
21	int size;
22	const char *name;
23	char *value = NULL;
24	struct posix_acl *acl;
25
26	switch (type) {
27	case ACL_TYPE_ACCESS:
28		name = XATTR_NAME_POSIX_ACL_ACCESS;
29		break;
30	case ACL_TYPE_DEFAULT:
31		name = XATTR_NAME_POSIX_ACL_DEFAULT;
32		break;
33	default:
34		return ERR_PTR(-EINVAL);
35	}
36
37	size = btrfs_getxattr(inode, name, NULL, 0);
38	if (size > 0) {
39		value = kzalloc(size, GFP_KERNEL);
40		if (!value)
41			return ERR_PTR(-ENOMEM);
42		size = btrfs_getxattr(inode, name, value, size);
43	}
44	if (size > 0)
45		acl = posix_acl_from_xattr(&init_user_ns, value, size);
46	else if (size == -ENODATA || size == 0)
47		acl = NULL;
48	else
49		acl = ERR_PTR(size);
50	kfree(value);
51
52	return acl;
53}
54
55static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
56			   struct user_namespace *mnt_userns,
57			   struct inode *inode, struct posix_acl *acl, int type)
58{
59	int ret, size = 0;
60	const char *name;
61	char *value = NULL;
62
63	switch (type) {
64	case ACL_TYPE_ACCESS:
65		name = XATTR_NAME_POSIX_ACL_ACCESS;
66		break;
67	case ACL_TYPE_DEFAULT:
68		if (!S_ISDIR(inode->i_mode))
69			return acl ? -EINVAL : 0;
70		name = XATTR_NAME_POSIX_ACL_DEFAULT;
71		break;
72	default:
73		return -EINVAL;
74	}
75
76	if (acl) {
77		unsigned int nofs_flag;
78
79		size = posix_acl_xattr_size(acl->a_count);
80		/*
81		 * We're holding a transaction handle, so use a NOFS memory
82		 * allocation context to avoid deadlock if reclaim happens.
83		 */
84		nofs_flag = memalloc_nofs_save();
85		value = kmalloc(size, GFP_KERNEL);
86		memalloc_nofs_restore(nofs_flag);
87		if (!value) {
88			ret = -ENOMEM;
89			goto out;
90		}
91
92		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
93		if (ret < 0)
94			goto out;
95	}
96
97	if (trans)
98		ret = btrfs_setxattr(trans, inode, name, value, size, 0);
99	else
100		ret = btrfs_setxattr_trans(inode, name, value, size, 0);
101
102out:
103	kfree(value);
104
105	if (!ret)
106		set_cached_acl(inode, type, acl);
107
108	return ret;
109}
110
111int btrfs_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
112		  struct posix_acl *acl, int type)
113{
114	int ret;
115	umode_t old_mode = inode->i_mode;
116
117	if (type == ACL_TYPE_ACCESS && acl) {
118		ret = posix_acl_update_mode(mnt_userns, inode,
119					    &inode->i_mode, &acl);
120		if (ret)
121			return ret;
122	}
123	ret = __btrfs_set_acl(NULL, mnt_userns, inode, acl, type);
124	if (ret)
125		inode->i_mode = old_mode;
126	return ret;
127}
128
129int btrfs_init_acl(struct btrfs_trans_handle *trans,
130		   struct inode *inode, struct inode *dir)
131{
132	struct posix_acl *default_acl, *acl;
133	int ret = 0;
134
135	/* this happens with subvols */
136	if (!dir)
137		return 0;
138
139	ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
140	if (ret)
141		return ret;
142
143	if (default_acl) {
144		ret = __btrfs_set_acl(trans, &init_user_ns, inode, default_acl,
145				      ACL_TYPE_DEFAULT);
146		posix_acl_release(default_acl);
147	}
148
149	if (acl) {
150		if (!ret)
151			ret = __btrfs_set_acl(trans, &init_user_ns, inode, acl,
152					      ACL_TYPE_ACCESS);
153		posix_acl_release(acl);
154	}
155
156	if (!default_acl && !acl)
157		cache_no_acl(inode);
158	return ret;
159}
160