1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2008 Christoph Hellwig.
4 * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
5 */
6
7 #include "xfs.h"
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_log_format.h"
11 #include "xfs_da_format.h"
12 #include "xfs_trans_resv.h"
13 #include "xfs_mount.h"
14 #include "xfs_inode.h"
15 #include "xfs_da_btree.h"
16 #include "xfs_attr.h"
17 #include "xfs_acl.h"
18 #include "xfs_log.h"
19 #include "xfs_xattr.h"
20
21 #include <linux/posix_acl_xattr.h>
22
23 /*
24 * Get permission to use log-assisted atomic exchange of file extents.
25 *
26 * Callers must not be running any transactions or hold any inode locks, and
27 * they must release the permission by calling xlog_drop_incompat_feat
28 * when they're done.
29 */
30 static inline int
xfs_attr_grab_log_assist(struct xfs_mount * mp)31 xfs_attr_grab_log_assist(
32 struct xfs_mount *mp)
33 {
34 int error = 0;
35
36 /*
37 * Protect ourselves from an idle log clearing the logged xattrs log
38 * incompat feature bit.
39 */
40 xlog_use_incompat_feat(mp->m_log);
41
42 /*
43 * If log-assisted xattrs are already enabled, the caller can use the
44 * log assisted swap functions with the log-incompat reference we got.
45 */
46 if (xfs_sb_version_haslogxattrs(&mp->m_sb))
47 return 0;
48
49 /*
50 * Check if the filesystem featureset is new enough to set this log
51 * incompat feature bit. Strictly speaking, the minimum requirement is
52 * a V5 filesystem for the superblock field, but we'll require rmap
53 * or reflink to avoid having to deal with really old kernels.
54 */
55 if (!xfs_has_reflink(mp) && !xfs_has_rmapbt(mp)) {
56 error = -EOPNOTSUPP;
57 goto drop_incompat;
58 }
59
60 /* Enable log-assisted xattrs. */
61 error = xfs_add_incompat_log_feature(mp,
62 XFS_SB_FEAT_INCOMPAT_LOG_XATTRS);
63 if (error)
64 goto drop_incompat;
65
66 xfs_warn_mount(mp, XFS_OPSTATE_WARNED_LARP,
67 "EXPERIMENTAL logged extended attributes feature in use. Use at your own risk!");
68
69 return 0;
70 drop_incompat:
71 xlog_drop_incompat_feat(mp->m_log);
72 return error;
73 }
74
75 static inline void
xfs_attr_rele_log_assist(struct xfs_mount * mp)76 xfs_attr_rele_log_assist(
77 struct xfs_mount *mp)
78 {
79 xlog_drop_incompat_feat(mp->m_log);
80 }
81
82 static inline bool
xfs_attr_want_log_assist(struct xfs_mount * mp)83 xfs_attr_want_log_assist(
84 struct xfs_mount *mp)
85 {
86 #ifdef DEBUG
87 /* Logged xattrs require a V5 super for log_incompat */
88 return xfs_has_crc(mp) && xfs_globals.larp;
89 #else
90 return false;
91 #endif
92 }
93
94 /*
95 * Set or remove an xattr, having grabbed the appropriate logging resources
96 * prior to calling libxfs.
97 */
98 int
xfs_attr_change(struct xfs_da_args * args)99 xfs_attr_change(
100 struct xfs_da_args *args)
101 {
102 struct xfs_mount *mp = args->dp->i_mount;
103 bool use_logging = false;
104 int error;
105
106 ASSERT(!(args->op_flags & XFS_DA_OP_LOGGED));
107
108 if (xfs_attr_want_log_assist(mp)) {
109 error = xfs_attr_grab_log_assist(mp);
110 if (error)
111 return error;
112
113 args->op_flags |= XFS_DA_OP_LOGGED;
114 use_logging = true;
115 }
116
117 error = xfs_attr_set(args);
118
119 if (use_logging)
120 xfs_attr_rele_log_assist(mp);
121 return error;
122 }
123
124
125 static int
xfs_xattr_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * value,size_t size)126 xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
127 struct inode *inode, const char *name, void *value, size_t size)
128 {
129 struct xfs_da_args args = {
130 .dp = XFS_I(inode),
131 .attr_filter = handler->flags,
132 .name = name,
133 .namelen = strlen(name),
134 .value = value,
135 .valuelen = size,
136 };
137 int error;
138
139 error = xfs_attr_get(&args);
140 if (error)
141 return error;
142 return args.valuelen;
143 }
144
145 static int
xfs_xattr_set(const struct xattr_handler * handler,struct mnt_idmap * idmap,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)146 xfs_xattr_set(const struct xattr_handler *handler,
147 struct mnt_idmap *idmap, struct dentry *unused,
148 struct inode *inode, const char *name, const void *value,
149 size_t size, int flags)
150 {
151 struct xfs_da_args args = {
152 .dp = XFS_I(inode),
153 .attr_filter = handler->flags,
154 .attr_flags = flags,
155 .name = name,
156 .namelen = strlen(name),
157 .value = (void *)value,
158 .valuelen = size,
159 };
160 int error;
161
162 error = xfs_attr_change(&args);
163 if (!error && (handler->flags & XFS_ATTR_ROOT))
164 xfs_forget_acl(inode, name);
165 return error;
166 }
167
168 static const struct xattr_handler xfs_xattr_user_handler = {
169 .prefix = XATTR_USER_PREFIX,
170 .flags = 0, /* no flags implies user namespace */
171 .get = xfs_xattr_get,
172 .set = xfs_xattr_set,
173 };
174
175 static const struct xattr_handler xfs_xattr_trusted_handler = {
176 .prefix = XATTR_TRUSTED_PREFIX,
177 .flags = XFS_ATTR_ROOT,
178 .get = xfs_xattr_get,
179 .set = xfs_xattr_set,
180 };
181
182 static const struct xattr_handler xfs_xattr_security_handler = {
183 .prefix = XATTR_SECURITY_PREFIX,
184 .flags = XFS_ATTR_SECURE,
185 .get = xfs_xattr_get,
186 .set = xfs_xattr_set,
187 };
188
189 const struct xattr_handler *xfs_xattr_handlers[] = {
190 &xfs_xattr_user_handler,
191 &xfs_xattr_trusted_handler,
192 &xfs_xattr_security_handler,
193 NULL
194 };
195
196 static void
__xfs_xattr_put_listent(struct xfs_attr_list_context * context,char * prefix,int prefix_len,unsigned char * name,int namelen)197 __xfs_xattr_put_listent(
198 struct xfs_attr_list_context *context,
199 char *prefix,
200 int prefix_len,
201 unsigned char *name,
202 int namelen)
203 {
204 char *offset;
205 int arraytop;
206
207 if (context->count < 0 || context->seen_enough)
208 return;
209
210 if (!context->buffer)
211 goto compute_size;
212
213 arraytop = context->count + prefix_len + namelen + 1;
214 if (arraytop > context->firstu) {
215 context->count = -1; /* insufficient space */
216 context->seen_enough = 1;
217 return;
218 }
219 offset = context->buffer + context->count;
220 memcpy(offset, prefix, prefix_len);
221 offset += prefix_len;
222 strncpy(offset, (char *)name, namelen); /* real name */
223 offset += namelen;
224 *offset = '\0';
225
226 compute_size:
227 context->count += prefix_len + namelen + 1;
228 return;
229 }
230
231 static void
xfs_xattr_put_listent(struct xfs_attr_list_context * context,int flags,unsigned char * name,int namelen,int valuelen)232 xfs_xattr_put_listent(
233 struct xfs_attr_list_context *context,
234 int flags,
235 unsigned char *name,
236 int namelen,
237 int valuelen)
238 {
239 char *prefix;
240 int prefix_len;
241
242 ASSERT(context->count >= 0);
243
244 if (flags & XFS_ATTR_ROOT) {
245 #ifdef CONFIG_XFS_POSIX_ACL
246 if (namelen == SGI_ACL_FILE_SIZE &&
247 strncmp(name, SGI_ACL_FILE,
248 SGI_ACL_FILE_SIZE) == 0) {
249 __xfs_xattr_put_listent(
250 context, XATTR_SYSTEM_PREFIX,
251 XATTR_SYSTEM_PREFIX_LEN,
252 XATTR_POSIX_ACL_ACCESS,
253 strlen(XATTR_POSIX_ACL_ACCESS));
254 } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
255 strncmp(name, SGI_ACL_DEFAULT,
256 SGI_ACL_DEFAULT_SIZE) == 0) {
257 __xfs_xattr_put_listent(
258 context, XATTR_SYSTEM_PREFIX,
259 XATTR_SYSTEM_PREFIX_LEN,
260 XATTR_POSIX_ACL_DEFAULT,
261 strlen(XATTR_POSIX_ACL_DEFAULT));
262 }
263 #endif
264
265 /*
266 * Only show root namespace entries if we are actually allowed to
267 * see them.
268 */
269 if (!capable(CAP_SYS_ADMIN))
270 return;
271
272 prefix = XATTR_TRUSTED_PREFIX;
273 prefix_len = XATTR_TRUSTED_PREFIX_LEN;
274 } else if (flags & XFS_ATTR_SECURE) {
275 prefix = XATTR_SECURITY_PREFIX;
276 prefix_len = XATTR_SECURITY_PREFIX_LEN;
277 } else {
278 prefix = XATTR_USER_PREFIX;
279 prefix_len = XATTR_USER_PREFIX_LEN;
280 }
281
282 __xfs_xattr_put_listent(context, prefix, prefix_len, name,
283 namelen);
284 return;
285 }
286
287 ssize_t
xfs_vn_listxattr(struct dentry * dentry,char * data,size_t size)288 xfs_vn_listxattr(
289 struct dentry *dentry,
290 char *data,
291 size_t size)
292 {
293 struct xfs_attr_list_context context;
294 struct inode *inode = d_inode(dentry);
295 int error;
296
297 /*
298 * First read the regular on-disk attributes.
299 */
300 memset(&context, 0, sizeof(context));
301 context.dp = XFS_I(inode);
302 context.resynch = 1;
303 context.buffer = size ? data : NULL;
304 context.bufsize = size;
305 context.firstu = context.bufsize;
306 context.put_listent = xfs_xattr_put_listent;
307
308 error = xfs_attr_list(&context);
309 if (error)
310 return error;
311 if (context.count < 0)
312 return -ERANGE;
313
314 return context.count;
315 }
316