xref: /openbmc/linux/fs/btrfs/acl.c (revision 31b90347)
1 /*
2  * Copyright (C) 2007 Red Hat.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 
19 #include <linux/fs.h>
20 #include <linux/string.h>
21 #include <linux/xattr.h>
22 #include <linux/posix_acl_xattr.h>
23 #include <linux/posix_acl.h>
24 #include <linux/sched.h>
25 #include <linux/slab.h>
26 
27 #include "ctree.h"
28 #include "btrfs_inode.h"
29 #include "xattr.h"
30 
31 struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
32 {
33 	int size;
34 	const char *name;
35 	char *value = NULL;
36 	struct posix_acl *acl;
37 
38 	if (!IS_POSIXACL(inode))
39 		return NULL;
40 
41 	acl = get_cached_acl(inode, type);
42 	if (acl != ACL_NOT_CACHED)
43 		return acl;
44 
45 	switch (type) {
46 	case ACL_TYPE_ACCESS:
47 		name = POSIX_ACL_XATTR_ACCESS;
48 		break;
49 	case ACL_TYPE_DEFAULT:
50 		name = POSIX_ACL_XATTR_DEFAULT;
51 		break;
52 	default:
53 		BUG();
54 	}
55 
56 	size = __btrfs_getxattr(inode, name, "", 0);
57 	if (size > 0) {
58 		value = kzalloc(size, GFP_NOFS);
59 		if (!value)
60 			return ERR_PTR(-ENOMEM);
61 		size = __btrfs_getxattr(inode, name, value, size);
62 	}
63 	if (size > 0) {
64 		acl = posix_acl_from_xattr(&init_user_ns, value, size);
65 	} else if (size == -ENOENT || size == -ENODATA || size == 0) {
66 		/* FIXME, who returns -ENOENT?  I think nobody */
67 		acl = NULL;
68 	} else {
69 		acl = ERR_PTR(-EIO);
70 	}
71 	kfree(value);
72 
73 	if (!IS_ERR(acl))
74 		set_cached_acl(inode, type, acl);
75 
76 	return acl;
77 }
78 
79 static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
80 		void *value, size_t size, int type)
81 {
82 	struct posix_acl *acl;
83 	int ret = 0;
84 
85 	if (!IS_POSIXACL(dentry->d_inode))
86 		return -EOPNOTSUPP;
87 
88 	acl = btrfs_get_acl(dentry->d_inode, type);
89 
90 	if (IS_ERR(acl))
91 		return PTR_ERR(acl);
92 	if (acl == NULL)
93 		return -ENODATA;
94 	ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
95 	posix_acl_release(acl);
96 
97 	return ret;
98 }
99 
100 /*
101  * Needs to be called with fs_mutex held
102  */
103 static int btrfs_set_acl(struct btrfs_trans_handle *trans,
104 			 struct inode *inode, struct posix_acl *acl, int type)
105 {
106 	int ret, size = 0;
107 	const char *name;
108 	char *value = NULL;
109 
110 	if (acl) {
111 		ret = posix_acl_valid(acl);
112 		if (ret < 0)
113 			return ret;
114 		ret = 0;
115 	}
116 
117 	switch (type) {
118 	case ACL_TYPE_ACCESS:
119 		name = POSIX_ACL_XATTR_ACCESS;
120 		if (acl) {
121 			ret = posix_acl_equiv_mode(acl, &inode->i_mode);
122 			if (ret < 0)
123 				return ret;
124 			if (ret == 0)
125 				acl = NULL;
126 		}
127 		ret = 0;
128 		break;
129 	case ACL_TYPE_DEFAULT:
130 		if (!S_ISDIR(inode->i_mode))
131 			return acl ? -EINVAL : 0;
132 		name = POSIX_ACL_XATTR_DEFAULT;
133 		break;
134 	default:
135 		return -EINVAL;
136 	}
137 
138 	if (acl) {
139 		size = posix_acl_xattr_size(acl->a_count);
140 		value = kmalloc(size, GFP_NOFS);
141 		if (!value) {
142 			ret = -ENOMEM;
143 			goto out;
144 		}
145 
146 		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
147 		if (ret < 0)
148 			goto out;
149 	}
150 
151 	ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
152 out:
153 	kfree(value);
154 
155 	if (!ret)
156 		set_cached_acl(inode, type, acl);
157 
158 	return ret;
159 }
160 
161 static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
162 		const void *value, size_t size, int flags, int type)
163 {
164 	int ret;
165 	struct posix_acl *acl = NULL;
166 
167 	if (!inode_owner_or_capable(dentry->d_inode))
168 		return -EPERM;
169 
170 	if (!IS_POSIXACL(dentry->d_inode))
171 		return -EOPNOTSUPP;
172 
173 	if (value) {
174 		acl = posix_acl_from_xattr(&init_user_ns, value, size);
175 		if (IS_ERR(acl))
176 			return PTR_ERR(acl);
177 
178 		if (acl) {
179 			ret = posix_acl_valid(acl);
180 			if (ret)
181 				goto out;
182 		}
183 	}
184 
185 	ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
186 out:
187 	posix_acl_release(acl);
188 
189 	return ret;
190 }
191 
192 /*
193  * btrfs_init_acl is already generally called under fs_mutex, so the locking
194  * stuff has been fixed to work with that.  If the locking stuff changes, we
195  * need to re-evaluate the acl locking stuff.
196  */
197 int btrfs_init_acl(struct btrfs_trans_handle *trans,
198 		   struct inode *inode, struct inode *dir)
199 {
200 	struct posix_acl *acl = NULL;
201 	int ret = 0;
202 
203 	/* this happens with subvols */
204 	if (!dir)
205 		return 0;
206 
207 	if (!S_ISLNK(inode->i_mode)) {
208 		if (IS_POSIXACL(dir)) {
209 			acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
210 			if (IS_ERR(acl))
211 				return PTR_ERR(acl);
212 		}
213 
214 		if (!acl)
215 			inode->i_mode &= ~current_umask();
216 	}
217 
218 	if (IS_POSIXACL(dir) && acl) {
219 		if (S_ISDIR(inode->i_mode)) {
220 			ret = btrfs_set_acl(trans, inode, acl,
221 					    ACL_TYPE_DEFAULT);
222 			if (ret)
223 				goto failed;
224 		}
225 		ret = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
226 		if (ret < 0)
227 			return ret;
228 
229 		if (ret > 0) {
230 			/* we need an acl */
231 			ret = btrfs_set_acl(trans, inode, acl, ACL_TYPE_ACCESS);
232 		} else if (ret < 0) {
233 			cache_no_acl(inode);
234 		}
235 	} else {
236 		cache_no_acl(inode);
237 	}
238 failed:
239 	posix_acl_release(acl);
240 
241 	return ret;
242 }
243 
244 int btrfs_acl_chmod(struct inode *inode)
245 {
246 	struct posix_acl *acl;
247 	int ret = 0;
248 
249 	if (S_ISLNK(inode->i_mode))
250 		return -EOPNOTSUPP;
251 
252 	if (!IS_POSIXACL(inode))
253 		return 0;
254 
255 	acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
256 	if (IS_ERR_OR_NULL(acl))
257 		return PTR_ERR(acl);
258 
259 	ret = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
260 	if (ret)
261 		return ret;
262 	ret = btrfs_set_acl(NULL, inode, acl, ACL_TYPE_ACCESS);
263 	posix_acl_release(acl);
264 	return ret;
265 }
266 
267 const struct xattr_handler btrfs_xattr_acl_default_handler = {
268 	.prefix = POSIX_ACL_XATTR_DEFAULT,
269 	.flags	= ACL_TYPE_DEFAULT,
270 	.get	= btrfs_xattr_acl_get,
271 	.set	= btrfs_xattr_acl_set,
272 };
273 
274 const struct xattr_handler btrfs_xattr_acl_access_handler = {
275 	.prefix = POSIX_ACL_XATTR_ACCESS,
276 	.flags	= ACL_TYPE_ACCESS,
277 	.get	= btrfs_xattr_acl_get,
278 	.set	= btrfs_xattr_acl_set,
279 };
280