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 /* Enable log-assisted xattrs. */
50 error = xfs_add_incompat_log_feature(mp,
51 XFS_SB_FEAT_INCOMPAT_LOG_XATTRS);
52 if (error)
53 goto drop_incompat;
54
55 xfs_warn_mount(mp, XFS_OPSTATE_WARNED_LARP,
56 "EXPERIMENTAL logged extended attributes feature in use. Use at your own risk!");
57
58 return 0;
59 drop_incompat:
60 xlog_drop_incompat_feat(mp->m_log);
61 return error;
62 }
63
64 static inline void
xfs_attr_rele_log_assist(struct xfs_mount * mp)65 xfs_attr_rele_log_assist(
66 struct xfs_mount *mp)
67 {
68 xlog_drop_incompat_feat(mp->m_log);
69 }
70
71 static inline bool
xfs_attr_want_log_assist(struct xfs_mount * mp)72 xfs_attr_want_log_assist(
73 struct xfs_mount *mp)
74 {
75 #ifdef DEBUG
76 /* Logged xattrs require a V5 super for log_incompat */
77 return xfs_has_crc(mp) && xfs_globals.larp;
78 #else
79 return false;
80 #endif
81 }
82
83 /*
84 * Set or remove an xattr, having grabbed the appropriate logging resources
85 * prior to calling libxfs.
86 */
87 int
xfs_attr_change(struct xfs_da_args * args)88 xfs_attr_change(
89 struct xfs_da_args *args)
90 {
91 struct xfs_mount *mp = args->dp->i_mount;
92 bool use_logging = false;
93 int error;
94
95 ASSERT(!(args->op_flags & XFS_DA_OP_LOGGED));
96
97 if (xfs_attr_want_log_assist(mp)) {
98 error = xfs_attr_grab_log_assist(mp);
99 if (error)
100 return error;
101
102 args->op_flags |= XFS_DA_OP_LOGGED;
103 use_logging = true;
104 }
105
106 error = xfs_attr_set(args);
107
108 if (use_logging)
109 xfs_attr_rele_log_assist(mp);
110 return error;
111 }
112
113
114 static int
xfs_xattr_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * value,size_t size)115 xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
116 struct inode *inode, const char *name, void *value, size_t size)
117 {
118 struct xfs_da_args args = {
119 .dp = XFS_I(inode),
120 .attr_filter = handler->flags,
121 .name = name,
122 .namelen = strlen(name),
123 .value = value,
124 .valuelen = size,
125 };
126 int error;
127
128 error = xfs_attr_get(&args);
129 if (error)
130 return error;
131 return args.valuelen;
132 }
133
134 static int
xfs_xattr_set(const struct xattr_handler * handler,struct user_namespace * mnt_userns,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)135 xfs_xattr_set(const struct xattr_handler *handler,
136 struct user_namespace *mnt_userns, struct dentry *unused,
137 struct inode *inode, const char *name, const void *value,
138 size_t size, int flags)
139 {
140 struct xfs_da_args args = {
141 .dp = XFS_I(inode),
142 .attr_filter = handler->flags,
143 .attr_flags = flags,
144 .name = name,
145 .namelen = strlen(name),
146 .value = (void *)value,
147 .valuelen = size,
148 };
149 int error;
150
151 error = xfs_attr_change(&args);
152 if (!error && (handler->flags & XFS_ATTR_ROOT))
153 xfs_forget_acl(inode, name);
154 return error;
155 }
156
157 static const struct xattr_handler xfs_xattr_user_handler = {
158 .prefix = XATTR_USER_PREFIX,
159 .flags = 0, /* no flags implies user namespace */
160 .get = xfs_xattr_get,
161 .set = xfs_xattr_set,
162 };
163
164 static const struct xattr_handler xfs_xattr_trusted_handler = {
165 .prefix = XATTR_TRUSTED_PREFIX,
166 .flags = XFS_ATTR_ROOT,
167 .get = xfs_xattr_get,
168 .set = xfs_xattr_set,
169 };
170
171 static const struct xattr_handler xfs_xattr_security_handler = {
172 .prefix = XATTR_SECURITY_PREFIX,
173 .flags = XFS_ATTR_SECURE,
174 .get = xfs_xattr_get,
175 .set = xfs_xattr_set,
176 };
177
178 const struct xattr_handler *xfs_xattr_handlers[] = {
179 &xfs_xattr_user_handler,
180 &xfs_xattr_trusted_handler,
181 &xfs_xattr_security_handler,
182 #ifdef CONFIG_XFS_POSIX_ACL
183 &posix_acl_access_xattr_handler,
184 &posix_acl_default_xattr_handler,
185 #endif
186 NULL
187 };
188
189 static void
__xfs_xattr_put_listent(struct xfs_attr_list_context * context,char * prefix,int prefix_len,unsigned char * name,int namelen)190 __xfs_xattr_put_listent(
191 struct xfs_attr_list_context *context,
192 char *prefix,
193 int prefix_len,
194 unsigned char *name,
195 int namelen)
196 {
197 char *offset;
198 int arraytop;
199
200 if (context->count < 0 || context->seen_enough)
201 return;
202
203 if (!context->buffer)
204 goto compute_size;
205
206 arraytop = context->count + prefix_len + namelen + 1;
207 if (arraytop > context->firstu) {
208 context->count = -1; /* insufficient space */
209 context->seen_enough = 1;
210 return;
211 }
212 offset = context->buffer + context->count;
213 strncpy(offset, prefix, prefix_len);
214 offset += prefix_len;
215 strncpy(offset, (char *)name, namelen); /* real name */
216 offset += namelen;
217 *offset = '\0';
218
219 compute_size:
220 context->count += prefix_len + namelen + 1;
221 return;
222 }
223
224 static void
xfs_xattr_put_listent(struct xfs_attr_list_context * context,int flags,unsigned char * name,int namelen,int valuelen)225 xfs_xattr_put_listent(
226 struct xfs_attr_list_context *context,
227 int flags,
228 unsigned char *name,
229 int namelen,
230 int valuelen)
231 {
232 char *prefix;
233 int prefix_len;
234
235 ASSERT(context->count >= 0);
236
237 if (flags & XFS_ATTR_ROOT) {
238 #ifdef CONFIG_XFS_POSIX_ACL
239 if (namelen == SGI_ACL_FILE_SIZE &&
240 strncmp(name, SGI_ACL_FILE,
241 SGI_ACL_FILE_SIZE) == 0) {
242 __xfs_xattr_put_listent(
243 context, XATTR_SYSTEM_PREFIX,
244 XATTR_SYSTEM_PREFIX_LEN,
245 XATTR_POSIX_ACL_ACCESS,
246 strlen(XATTR_POSIX_ACL_ACCESS));
247 } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
248 strncmp(name, SGI_ACL_DEFAULT,
249 SGI_ACL_DEFAULT_SIZE) == 0) {
250 __xfs_xattr_put_listent(
251 context, XATTR_SYSTEM_PREFIX,
252 XATTR_SYSTEM_PREFIX_LEN,
253 XATTR_POSIX_ACL_DEFAULT,
254 strlen(XATTR_POSIX_ACL_DEFAULT));
255 }
256 #endif
257
258 /*
259 * Only show root namespace entries if we are actually allowed to
260 * see them.
261 */
262 if (!capable(CAP_SYS_ADMIN))
263 return;
264
265 prefix = XATTR_TRUSTED_PREFIX;
266 prefix_len = XATTR_TRUSTED_PREFIX_LEN;
267 } else if (flags & XFS_ATTR_SECURE) {
268 prefix = XATTR_SECURITY_PREFIX;
269 prefix_len = XATTR_SECURITY_PREFIX_LEN;
270 } else {
271 prefix = XATTR_USER_PREFIX;
272 prefix_len = XATTR_USER_PREFIX_LEN;
273 }
274
275 __xfs_xattr_put_listent(context, prefix, prefix_len, name,
276 namelen);
277 return;
278 }
279
280 ssize_t
xfs_vn_listxattr(struct dentry * dentry,char * data,size_t size)281 xfs_vn_listxattr(
282 struct dentry *dentry,
283 char *data,
284 size_t size)
285 {
286 struct xfs_attr_list_context context;
287 struct inode *inode = d_inode(dentry);
288 int error;
289
290 /*
291 * First read the regular on-disk attributes.
292 */
293 memset(&context, 0, sizeof(context));
294 context.dp = XFS_I(inode);
295 context.resynch = 1;
296 context.buffer = size ? data : NULL;
297 context.bufsize = size;
298 context.firstu = context.bufsize;
299 context.put_listent = xfs_xattr_put_listent;
300
301 error = xfs_attr_list(&context);
302 if (error)
303 return error;
304 if (context.count < 0)
305 return -ERANGE;
306
307 return context.count;
308 }
309