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 
btrfs_get_acl(struct inode * inode,int type,bool rcu)19 struct 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 
__btrfs_set_acl(struct btrfs_trans_handle * trans,struct inode * inode,struct posix_acl * acl,int type)58 int __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 
104 out:
105 	kfree(value);
106 
107 	if (!ret)
108 		set_cached_acl(inode, type, acl);
109 
110 	return ret;
111 }
112 
btrfs_set_acl(struct mnt_idmap * idmap,struct dentry * dentry,struct posix_acl * acl,int type)113 int 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