1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2008, Christoph Hellwig
4 * All Rights Reserved.
5 */
6 #include "xfs.h"
7 #include "xfs_shared.h"
8 #include "xfs_format.h"
9 #include "xfs_log_format.h"
10 #include "xfs_trans_resv.h"
11 #include "xfs_mount.h"
12 #include "xfs_inode.h"
13 #include "xfs_da_format.h"
14 #include "xfs_da_btree.h"
15 #include "xfs_attr.h"
16 #include "xfs_trace.h"
17 #include "xfs_error.h"
18 #include "xfs_acl.h"
19 #include "xfs_trans.h"
20 #include "xfs_xattr.h"
21
22 #include <linux/posix_acl_xattr.h>
23
24 /*
25 * Locking scheme:
26 * - all ACL updates are protected by inode->i_mutex, which is taken before
27 * calling into this file.
28 */
29
30 STATIC struct posix_acl *
31 xfs_acl_from_disk(
32 struct xfs_mount *mp,
33 const struct xfs_acl *aclp,
34 int len,
35 int max_entries)
36 {
37 struct posix_acl_entry *acl_e;
38 struct posix_acl *acl;
39 const struct xfs_acl_entry *ace;
40 unsigned int count, i;
41
42 if (len < sizeof(*aclp)) {
43 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
44 len);
45 return ERR_PTR(-EFSCORRUPTED);
46 }
47
48 count = be32_to_cpu(aclp->acl_cnt);
49 if (count > max_entries || XFS_ACL_SIZE(count) != len) {
50 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
51 len);
52 return ERR_PTR(-EFSCORRUPTED);
53 }
54
55 acl = posix_acl_alloc(count, GFP_KERNEL);
56 if (!acl)
57 return ERR_PTR(-ENOMEM);
58
59 for (i = 0; i < count; i++) {
60 acl_e = &acl->a_entries[i];
61 ace = &aclp->acl_entry[i];
62
63 /*
64 * The tag is 32 bits on disk and 16 bits in core.
65 *
66 * Because every access to it goes through the core
67 * format first this is not a problem.
68 */
69 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
70 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
71
72 switch (acl_e->e_tag) {
73 case ACL_USER:
74 acl_e->e_uid = make_kuid(&init_user_ns,
75 be32_to_cpu(ace->ae_id));
76 break;
77 case ACL_GROUP:
78 acl_e->e_gid = make_kgid(&init_user_ns,
79 be32_to_cpu(ace->ae_id));
80 break;
81 case ACL_USER_OBJ:
82 case ACL_GROUP_OBJ:
83 case ACL_MASK:
84 case ACL_OTHER:
85 break;
86 default:
87 goto fail;
88 }
89 }
90 return acl;
91
92 fail:
93 posix_acl_release(acl);
94 return ERR_PTR(-EINVAL);
95 }
96
97 STATIC void
98 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
99 {
100 const struct posix_acl_entry *acl_e;
101 struct xfs_acl_entry *ace;
102 int i;
103
104 aclp->acl_cnt = cpu_to_be32(acl->a_count);
105 for (i = 0; i < acl->a_count; i++) {
106 ace = &aclp->acl_entry[i];
107 acl_e = &acl->a_entries[i];
108
109 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
110 switch (acl_e->e_tag) {
111 case ACL_USER:
112 ace->ae_id = cpu_to_be32(
113 from_kuid(&init_user_ns, acl_e->e_uid));
114 break;
115 case ACL_GROUP:
116 ace->ae_id = cpu_to_be32(
117 from_kgid(&init_user_ns, acl_e->e_gid));
118 break;
119 default:
120 ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
121 break;
122 }
123
124 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
125 }
126 }
127
128 struct posix_acl *
129 xfs_get_acl(struct inode *inode, int type, bool rcu)
130 {
131 struct xfs_inode *ip = XFS_I(inode);
132 struct xfs_mount *mp = ip->i_mount;
133 struct posix_acl *acl = NULL;
134 struct xfs_da_args args = {
135 .dp = ip,
136 .attr_filter = XFS_ATTR_ROOT,
137 .valuelen = XFS_ACL_MAX_SIZE(mp),
138 };
139 int error;
140
141 if (rcu)
142 return ERR_PTR(-ECHILD);
143
144 trace_xfs_get_acl(ip);
145
146 switch (type) {
147 case ACL_TYPE_ACCESS:
148 args.name = SGI_ACL_FILE;
149 break;
150 case ACL_TYPE_DEFAULT:
151 args.name = SGI_ACL_DEFAULT;
152 break;
153 default:
154 BUG();
155 }
156 args.namelen = strlen(args.name);
157
158 /*
159 * If the attribute doesn't exist make sure we have a negative cache
160 * entry, for any other error assume it is transient.
161 */
162 error = xfs_attr_get(&args);
163 if (!error) {
164 acl = xfs_acl_from_disk(mp, args.value, args.valuelen,
165 XFS_ACL_MAX_ENTRIES(mp));
166 } else if (error != -ENOATTR) {
167 acl = ERR_PTR(error);
168 }
169
170 kvfree(args.value);
171 return acl;
172 }
173
174 int
175 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
176 {
177 struct xfs_inode *ip = XFS_I(inode);
178 struct xfs_da_args args = {
179 .dp = ip,
180 .attr_filter = XFS_ATTR_ROOT,
181 };
182 int error;
183
184 switch (type) {
185 case ACL_TYPE_ACCESS:
186 args.name = SGI_ACL_FILE;
187 break;
188 case ACL_TYPE_DEFAULT:
189 if (!S_ISDIR(inode->i_mode))
190 return acl ? -EACCES : 0;
191 args.name = SGI_ACL_DEFAULT;
192 break;
193 default:
194 return -EINVAL;
195 }
196 args.namelen = strlen(args.name);
197
198 if (acl) {
199 args.valuelen = XFS_ACL_SIZE(acl->a_count);
200 args.value = kvzalloc(args.valuelen, GFP_KERNEL);
201 if (!args.value)
202 return -ENOMEM;
203 xfs_acl_to_disk(args.value, acl);
204 error = xfs_attr_change(&args, XFS_ATTRUPDATE_UPSERT);
205 kvfree(args.value);
206 } else {
207 error = xfs_attr_change(&args, XFS_ATTRUPDATE_REMOVE);
208 /*
209 * If the attribute didn't exist to start with that's fine.
210 */
211 if (error == -ENOATTR)
212 error = 0;
213 }
214
215 if (!error)
216 set_cached_acl(inode, type, acl);
217 return error;
218 }
219
220 static int
221 xfs_acl_set_mode(
222 struct inode *inode,
223 umode_t mode)
224 {
225 struct xfs_inode *ip = XFS_I(inode);
226 struct xfs_mount *mp = ip->i_mount;
227 struct xfs_trans *tp;
228 int error;
229
230 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
231 if (error)
232 return error;
233
234 xfs_ilock(ip, XFS_ILOCK_EXCL);
235 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
236 inode->i_mode = mode;
237 inode_set_ctime_current(inode);
238 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
239
240 if (xfs_has_wsync(mp))
241 xfs_trans_set_sync(tp);
242 return xfs_trans_commit(tp);
243 }
244
245 int
246 xfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
247 struct posix_acl *acl, int type)
248 {
249 umode_t mode;
250 bool set_mode = false;
251 int error = 0;
252 struct inode *inode = d_inode(dentry);
253
254 if (!acl)
255 goto set_acl;
256
257 error = -E2BIG;
258 if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
259 return error;
260
261 if (type == ACL_TYPE_ACCESS) {
262 error = posix_acl_update_mode(idmap, inode, &mode, &acl);
263 if (error)
264 return error;
265 set_mode = true;
266 }
267
268 set_acl:
269 /*
270 * We set the mode after successfully updating the ACL xattr because the
271 * xattr update can fail at ENOSPC and we don't want to change the mode
272 * if the ACL update hasn't been applied.
273 */
274 error = __xfs_set_acl(inode, acl, type);
275 if (!error && set_mode && mode != inode->i_mode)
276 error = xfs_acl_set_mode(inode, mode);
277 return error;
278 }
279
280 /*
281 * Invalidate any cached ACLs if the user has bypassed the ACL interface.
282 * We don't validate the content whatsoever so it is caller responsibility to
283 * provide data in valid format and ensure i_mode is consistent.
284 */
285 void
286 xfs_forget_acl(
287 struct inode *inode,
288 const char *name)
289 {
290 if (!strcmp(name, SGI_ACL_FILE))
291 forget_cached_acl(inode, ACL_TYPE_ACCESS);
292 else if (!strcmp(name, SGI_ACL_DEFAULT))
293 forget_cached_acl(inode, ACL_TYPE_DEFAULT);
294 }
295
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