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 */
30static inline int
31xfs_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(log: 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 feature: 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;
70drop_incompat:
71 xlog_drop_incompat_feat(log: mp->m_log);
72 return error;
73}
74
75static inline void
76xfs_attr_rele_log_assist(
77 struct xfs_mount *mp)
78{
79 xlog_drop_incompat_feat(log: mp->m_log);
80}
81
82static inline bool
83xfs_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 */
98int
99xfs_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
125static int
126xfs_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
145static int
146xfs_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: &args);
163 if (!error && (handler->flags & XFS_ATTR_ROOT))
164 xfs_forget_acl(inode, name);
165 return error;
166}
167
168static 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
175static 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
182static 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
189const struct xattr_handler * const xfs_xattr_handlers[] = {
190 &xfs_xattr_user_handler,
191 &xfs_xattr_trusted_handler,
192 &xfs_xattr_security_handler,
193 NULL
194};
195
196static void
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(p: offset, q: (char *)name, size: namelen); /* real name */
223 offset += namelen;
224 *offset = '\0';
225
226compute_size:
227 context->count += prefix_len + namelen + 1;
228 return;
229}
230
231static void
232xfs_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
287ssize_t
288xfs_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

source code of linux/fs/xfs/xfs_xattr.c