1/*
 2 * FUSE: Filesystem in Userspace
 3 * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>
 4 *
 5 * This program can be distributed under the terms of the GNU GPL.
 6 * See the file COPYING.
 7 */
 8
 9#include "fuse_i.h"
10
11#include <linux/posix_acl.h>
12#include <linux/posix_acl_xattr.h>
13
14struct posix_acl *fuse_get_acl(struct inode *inode, int type)
15{
16	struct fuse_conn *fc = get_fuse_conn(inode);
17	int size;
18	const char *name;
19	void *value = NULL;
20	struct posix_acl *acl;
21
22	if (!fc->posix_acl || fc->no_getxattr)
23		return NULL;
24
25	if (type == ACL_TYPE_ACCESS)
26		name = XATTR_NAME_POSIX_ACL_ACCESS;
27	else if (type == ACL_TYPE_DEFAULT)
28		name = XATTR_NAME_POSIX_ACL_DEFAULT;
29	else
30		return ERR_PTR(-EOPNOTSUPP);
31
32	value = kmalloc(PAGE_SIZE, GFP_KERNEL);
33	if (!value)
34		return ERR_PTR(-ENOMEM);
35	size = fuse_getxattr(inode, name, value, PAGE_SIZE);
36	if (size > 0)
37		acl = posix_acl_from_xattr(fc->user_ns, value, size);
38	else if ((size == 0) || (size == -ENODATA) ||
39		 (size == -EOPNOTSUPP && fc->no_getxattr))
40		acl = NULL;
41	else if (size == -ERANGE)
42		acl = ERR_PTR(-E2BIG);
43	else
44		acl = ERR_PTR(size);
45
46	kfree(value);
47	return acl;
48}
49
50int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)
51{
52	struct fuse_conn *fc = get_fuse_conn(inode);
53	const char *name;
54	int ret;
55
56	if (!fc->posix_acl || fc->no_setxattr)
57		return -EOPNOTSUPP;
58
59	if (type == ACL_TYPE_ACCESS)
60		name = XATTR_NAME_POSIX_ACL_ACCESS;
61	else if (type == ACL_TYPE_DEFAULT)
62		name = XATTR_NAME_POSIX_ACL_DEFAULT;
63	else
64		return -EINVAL;
65
66	if (acl) {
67		/*
68		 * Fuse userspace is responsible for updating access
69		 * permissions in the inode, if needed. fuse_setxattr
70		 * invalidates the inode attributes, which will force
71		 * them to be refreshed the next time they are used,
72		 * and it also updates i_ctime.
73		 */
74		size_t size = posix_acl_xattr_size(acl->a_count);
75		void *value;
76
77		if (size > PAGE_SIZE)
78			return -E2BIG;
79
80		value = kmalloc(size, GFP_KERNEL);
81		if (!value)
82			return -ENOMEM;
83
84		ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
85		if (ret < 0) {
86			kfree(value);
87			return ret;
88		}
89
90		ret = fuse_setxattr(inode, name, value, size, 0);
91		kfree(value);
92	} else {
93		ret = fuse_removexattr(inode, name);
94	}
95	forget_all_cached_acls(inode);
96	fuse_invalidate_attr(inode);
97
98	return ret;
99}