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