xref: /kernel/linux/linux-6.6/fs/btrfs/acl.c (revision 62306a36) 
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 "btrfs_inode.h"
16#include "xattr.h"
17#include "acl.h"
18
19struct posix_acl *btrfs_get_acl(struct inode *inode, int type, bool rcu)
20{
21	int size;
22	const char *name;
23	char *value = NULL;
24	struct posix_acl *acl;
25
26	if (rcu)
27		return ERR_PTR(-ECHILD);
28
29	switch (type) {
30	case ACL_TYPE_ACCESS:
31		name = XATTR_NAME_POSIX_ACL_ACCESS;
32		break;
33	case ACL_TYPE_DEFAULT:
34		name = XATTR_NAME_POSIX_ACL_DEFAULT;
35		break;
36	default:
37		return ERR_PTR(-EINVAL);
38	}
39
40	size = btrfs_getxattr(inode, name, NULL, 0);
41	if (size > 0) {
42		value = kzalloc(size, GFP_KERNEL);
43		if (!value)
44			return ERR_PTR(-ENOMEM);
45		size = btrfs_getxattr(inode, name, value, size);
46	}
47	if (size > 0)
48		acl = posix_acl_from_xattr(&init_user_ns, value, size);
49	else if (size == -ENODATA || size == 0)
50		acl = NULL;
51	else
52		acl = ERR_PTR(size);
53	kfree(value);
54
55	return acl;
56}
57
58int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,
59		    struct posix_acl *acl, int type)
60{
61	int ret, size = 0;
62	const char *name;
63	char *value = NULL;
64
65	switch (type) {
66	case ACL_TYPE_ACCESS:
67		name = XATTR_NAME_POSIX_ACL_ACCESS;
68		break;
69	case ACL_TYPE_DEFAULT:
70		if (!S_ISDIR(inode->i_mode))
71			return acl ? -EINVAL : 0;
72		name = XATTR_NAME_POSIX_ACL_DEFAULT;
73		break;
74	default:
75		return -EINVAL;
76	}
77
78	if (acl) {
79		unsigned int nofs_flag;
80
81		size = posix_acl_xattr_size(acl->a_count);
82		/*
83		 * We're holding a transaction handle, so use a NOFS memory
84		 * allocation context to avoid deadlock if reclaim happens.
85		 */
86		nofs_flag = memalloc_nofs_save();
87		value = kmalloc(size, GFP_KERNEL);
88		memalloc_nofs_restore(nofs_flag);
89		if (!value) {
90			ret = -ENOMEM;
91			goto out;
92		}
93
94		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
95		if (ret < 0)
96			goto out;
97	}
98
99	if (trans)
100		ret = btrfs_setxattr(trans, inode, name, value, size, 0);
101	else
102		ret = btrfs_setxattr_trans(inode, name, value, size, 0);
103
104out:
105	kfree(value);
106
107	if (!ret)
108		set_cached_acl(inode, type, acl);
109
110	return ret;
111}
112
113int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
114		  struct posix_acl *acl, int type)
115{
116	int ret;
117	struct inode *inode = d_inode(dentry);
118	umode_t old_mode = inode->i_mode;
119
120	if (type == ACL_TYPE_ACCESS && acl) {
121		ret = posix_acl_update_mode(idmap, inode,
122					    &inode->i_mode, &acl);
123		if (ret)
124			return ret;
125	}
126	ret = __btrfs_set_acl(NULL, inode, acl, type);
127	if (ret)
128		inode->i_mode = old_mode;
129	return ret;
130}
131