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1 | /* |
2 | * CDDL HEADER START | |
3 | * | |
4 | * The contents of this file are subject to the terms of the | |
5 | * Common Development and Distribution License (the "License"). | |
6 | * You may not use this file except in compliance with the License. | |
7 | * | |
8 | * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE | |
9 | * or http://www.opensolaris.org/os/licensing. | |
10 | * See the License for the specific language governing permissions | |
11 | * and limitations under the License. | |
12 | * | |
13 | * When distributing Covered Code, include this CDDL HEADER in each | |
14 | * file and include the License file at usr/src/OPENSOLARIS.LICENSE. | |
15 | * If applicable, add the following below this CDDL HEADER, with the | |
16 | * fields enclosed by brackets "[]" replaced with your own identifying | |
17 | * information: Portions Copyright [yyyy] [name of copyright owner] | |
18 | * | |
19 | * CDDL HEADER END | |
20 | */ | |
21 | /* | |
22 | * Copyright (c) 2011, Lawrence Livermore National Security, LLC. | |
23 | * | |
24 | * Extended attributes (xattr) on Solaris are implemented as files | |
25 | * which exist in a hidden xattr directory. These extended attributes | |
26 | * can be accessed using the attropen() system call which opens | |
27 | * the extended attribute. It can then be manipulated just like | |
28 | * a standard file descriptor. This has a couple advantages such | |
29 | * as practically no size limit on the file, and the extended | |
30 | * attributes permissions may differ from those of the parent file. | |
31 | * This interface is really quite clever, but it's also completely | |
32 | * different than what is supported on Linux. | |
33 | * | |
34 | * Under Linux extended attributes are manipulated by the system | |
35 | * calls getxattr(2), setxattr(2), and listxattr(2). They consider | |
36 | * extended attributes to be name/value pairs where the name is a | |
37 | * NULL terminated string. The name must also include one of the | |
38 | * following name space prefixes: | |
39 | * | |
40 | * user - No restrictions and is available to user applications. | |
41 | * trusted - Restricted to kernel and root (CAP_SYS_ADMIN) use. | |
42 | * system - Used for access control lists (system.nfs4_acl, etc). | |
43 | * security - Used by SELinux to store a files security context. | |
44 | * | |
45 | * This Linux interface is implemented internally using the more | |
46 | * flexible Solaris style extended attributes. Every extended | |
47 | * attribute is store as a file in a hidden directory associated | |
48 | * with the parent file. This ensures on disk compatibility with | |
49 | * zfs implementations on other platforms (Solaris, FreeBSD, MacOS). | |
50 | * | |
51 | * One consequence of this implementation is that when an extended | |
52 | * attribute is manipulated an inode is created. This inode will | |
53 | * exist in the Linux inode cache but there will be no associated | |
54 | * entry in the dentry cache which references it. This is safe | |
55 | * but it may result in some confusion. | |
56 | * | |
57 | * Longer term I would like to see the 'security.selinux' extended | |
58 | * attribute moved to a SA. This should significantly improve | |
59 | * performance on a SELinux enabled system by minimizing the | |
60 | * number of seeks required to access a file. However, for now | |
61 | * this xattr is still stored in a file because I'm pretty sure | |
62 | * adding a new SA will break on-disk compatibility. | |
63 | */ | |
64 | ||
65 | ||
66 | #include <sys/zfs_vfsops.h> | |
67 | #include <sys/zfs_vnops.h> | |
68 | #include <sys/zfs_znode.h> | |
69 | #include <sys/vfs.h> | |
70 | #include <sys/zpl.h> | |
71 | ||
72 | typedef struct xattr_filldir { | |
73 | size_t size; | |
74 | size_t offset; | |
75 | char *buf; | |
76 | struct inode *inode; | |
77 | } xattr_filldir_t; | |
78 | ||
79 | static int | |
80 | zpl_xattr_filldir(void *arg, const char *name, int name_len, | |
81 | loff_t offset, uint64_t objnum, unsigned int d_type) | |
82 | { | |
83 | xattr_filldir_t *xf = arg; | |
84 | ||
85 | if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) | |
86 | if (!(ITOZSB(xf->inode)->z_flags & ZSB_XATTR_USER)) | |
87 | return (0); | |
88 | ||
89 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) | |
90 | if (!capable(CAP_SYS_ADMIN)) | |
91 | return (0); | |
92 | ||
93 | /* When xf->buf is NULL only calculate the required size. */ | |
94 | if (xf->buf) { | |
95 | if (xf->offset + name_len + 1 > xf->size) | |
96 | return (-ERANGE); | |
97 | ||
98 | memcpy(xf->buf + xf->offset, name, name_len); | |
99 | xf->buf[xf->offset + name_len] = '\0'; | |
100 | } | |
101 | ||
102 | xf->offset += (name_len + 1); | |
103 | ||
104 | return (0); | |
105 | } | |
106 | ||
107 | ssize_t | |
108 | zpl_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) | |
109 | { | |
110 | struct inode *ip = dentry->d_inode; | |
111 | struct inode *dxip = NULL; | |
112 | loff_t pos = 3; /* skip '.', '..', and '.zfs' entries. */ | |
113 | cred_t *cr; | |
114 | int error; | |
115 | xattr_filldir_t xf = { buffer_size, 0, buffer, ip }; | |
116 | ||
117 | cr = (cred_t *)get_current_cred(); | |
118 | ||
119 | /* Lookup the xattr directory */ | |
120 | error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR, cr, NULL, NULL); | |
121 | if (error) { | |
122 | if (error == -ENOENT) | |
123 | error = 0; | |
124 | ||
125 | goto out; | |
126 | } | |
127 | ||
128 | /* Fill provided buffer via zpl_zattr_filldir helper */ | |
129 | error = -zfs_readdir(dxip, (void *)&xf, zpl_xattr_filldir, &pos, cr); | |
130 | if (error) | |
131 | goto out; | |
132 | ||
133 | error = xf.offset; | |
134 | out: | |
135 | if (dxip) | |
136 | iput(dxip); | |
137 | ||
138 | put_cred(cr); | |
139 | ||
140 | return (error); | |
141 | } | |
142 | ||
143 | static int | |
144 | zpl_xattr_get(struct inode *ip, const char *name, void *buf, size_t size) | |
145 | { | |
146 | struct inode *dxip = NULL; | |
147 | struct inode *xip = NULL; | |
148 | cred_t *cr; | |
149 | int error; | |
150 | ||
151 | cr = (cred_t *)get_current_cred(); | |
152 | ||
153 | /* Lookup the xattr directory */ | |
154 | error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR, cr, NULL, NULL); | |
155 | if (error) | |
156 | goto out; | |
157 | ||
158 | /* Lookup a specific xattr name in the directory */ | |
159 | error = -zfs_lookup(dxip, (char *)name, &xip, 0, cr, NULL, NULL); | |
160 | if (error) | |
161 | goto out; | |
162 | ||
163 | if (!size) { | |
164 | error = i_size_read(xip); | |
165 | goto out; | |
166 | } | |
167 | ||
168 | error = zpl_read_common(xip, buf, size, 0, UIO_SYSSPACE, 0, cr); | |
169 | out: | |
170 | if (xip) | |
171 | iput(xip); | |
172 | ||
173 | if (dxip) | |
174 | iput(dxip); | |
175 | ||
176 | put_cred(cr); | |
177 | ||
178 | if (error == -ENOENT) | |
179 | error = -ENODATA; | |
180 | ||
181 | return (error); | |
182 | } | |
183 | ||
184 | static int | |
185 | zpl_xattr_set(struct inode *ip, const char *name, const void *value, | |
186 | size_t size, int flags) | |
187 | { | |
188 | struct inode *dxip = NULL; | |
189 | struct inode *xip = NULL; | |
190 | vattr_t *vap = NULL; | |
191 | cred_t *cr; | |
192 | ssize_t wrote; | |
193 | int error; | |
194 | ||
195 | cr = (cred_t *)get_current_cred(); | |
196 | ||
197 | /* Lookup the xattr directory and create it if required. */ | |
198 | error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR | CREATE_XATTR_DIR, | |
199 | cr, NULL, NULL); | |
200 | if (error) | |
201 | goto out; | |
202 | ||
203 | /* | |
204 | * Lookup a specific xattr name in the directory, two failure modes: | |
205 | * XATTR_CREATE: fail if xattr already exists | |
206 | * XATTR_REMOVE: fail if xattr does not exist | |
207 | */ | |
208 | error = -zfs_lookup(dxip, (char *)name, &xip, 0, cr, NULL, NULL); | |
209 | if (error) { | |
210 | if (error != -ENOENT) | |
211 | goto out; | |
212 | ||
213 | if ((error == -ENOENT) && (flags & XATTR_REPLACE)) | |
214 | goto out; | |
215 | } else { | |
216 | error = -EEXIST; | |
217 | if (flags & XATTR_CREATE) | |
218 | goto out; | |
219 | } | |
220 | error = 0; | |
221 | ||
222 | /* Remove a specific name xattr when value is set to NULL. */ | |
223 | if (value == NULL) { | |
224 | if (xip) | |
225 | error = -zfs_remove(dxip, (char *)name, cr); | |
226 | ||
227 | goto out; | |
228 | } | |
229 | ||
230 | /* Lookup failed create a new xattr. */ | |
231 | if (xip == NULL) { | |
232 | vap = kmem_zalloc(sizeof(vattr_t), KM_SLEEP); | |
233 | vap->va_mode = S_IFREG | 0644; | |
234 | vap->va_mask = ATTR_MODE; | |
235 | vap->va_uid = current_fsuid(); | |
236 | vap->va_gid = current_fsgid(); | |
237 | ||
238 | error = -zfs_create(dxip, (char *)name, vap, 0, 0644, &xip, | |
239 | cr, 0, NULL); | |
240 | if (error) | |
241 | goto out; | |
242 | } | |
243 | ||
244 | ASSERT(xip != NULL); | |
245 | wrote = zpl_write_common(xip, value, size, 0, UIO_SYSSPACE, 0, cr); | |
246 | if (wrote < 0) | |
247 | error = wrote; | |
248 | ||
249 | out: | |
250 | if (vap) | |
251 | kmem_free(vap, sizeof(vattr_t)); | |
252 | ||
253 | if (xip) | |
254 | iput(xip); | |
255 | ||
256 | if (dxip) | |
257 | iput(dxip); | |
258 | ||
259 | put_cred(cr); | |
260 | if (error == -ENOENT) | |
261 | error = -ENODATA; | |
262 | ||
263 | ASSERT3S(error, <=, 0); | |
264 | ||
265 | return (error); | |
266 | } | |
267 | ||
268 | static int | |
269 | zpl_xattr_user_get(struct inode *ip, const char *name, | |
270 | void *buffer, size_t size) | |
271 | { | |
272 | char *xattr_name; | |
273 | int error; | |
274 | ||
275 | if (strcmp(name, "") == 0) | |
276 | return -EINVAL; | |
277 | ||
278 | if (!(ITOZSB(ip)->z_flags & ZSB_XATTR_USER)) | |
279 | return -EOPNOTSUPP; | |
280 | ||
281 | xattr_name = kmem_asprintf("%s%s", XATTR_USER_PREFIX, name); | |
282 | error = zpl_xattr_get(ip, xattr_name, buffer, size); | |
283 | strfree(xattr_name); | |
284 | ||
285 | return (error); | |
286 | } | |
287 | ||
288 | static int | |
289 | zpl_xattr_user_set(struct inode *ip, const char *name, | |
290 | const void *value, size_t size, int flags) | |
291 | { | |
292 | char *xattr_name; | |
293 | int error; | |
294 | ||
295 | if (strcmp(name, "") == 0) | |
296 | return -EINVAL; | |
297 | ||
298 | if (!(ITOZSB(ip)->z_flags & ZSB_XATTR_USER)) | |
299 | return -EOPNOTSUPP; | |
300 | ||
301 | xattr_name = kmem_asprintf("%s%s", XATTR_USER_PREFIX, name); | |
302 | error = zpl_xattr_set(ip, xattr_name, value, size, flags); | |
303 | strfree(xattr_name); | |
304 | ||
305 | return (error); | |
306 | } | |
307 | ||
308 | struct xattr_handler zpl_xattr_user_handler = { | |
309 | .prefix = XATTR_USER_PREFIX, | |
310 | .get = zpl_xattr_user_get, | |
311 | .set = zpl_xattr_user_set, | |
312 | }; | |
313 | ||
314 | static int | |
315 | zpl_xattr_trusted_get(struct inode *ip, const char *name, | |
316 | void *buffer, size_t size) | |
317 | { | |
318 | char *xattr_name; | |
319 | int error; | |
320 | ||
321 | if (!capable(CAP_SYS_ADMIN)) | |
322 | return -EACCES; | |
323 | ||
324 | if (strcmp(name, "") == 0) | |
325 | return -EINVAL; | |
326 | ||
327 | xattr_name = kmem_asprintf("%s%s", XATTR_TRUSTED_PREFIX, name); | |
328 | error = zpl_xattr_get(ip, xattr_name, buffer, size); | |
329 | strfree(xattr_name); | |
330 | ||
331 | return (error); | |
332 | } | |
333 | ||
334 | static int | |
335 | zpl_xattr_trusted_set(struct inode *ip, const char *name, | |
336 | const void *value, size_t size, int flags) | |
337 | { | |
338 | char *xattr_name; | |
339 | int error; | |
340 | ||
341 | if (!capable(CAP_SYS_ADMIN)) | |
342 | return -EACCES; | |
343 | ||
344 | if (strcmp(name, "") == 0) | |
345 | return -EINVAL; | |
346 | ||
347 | xattr_name = kmem_asprintf("%s%s", XATTR_TRUSTED_PREFIX, name); | |
348 | error = zpl_xattr_set(ip, xattr_name, value, size, flags); | |
349 | strfree(xattr_name); | |
350 | ||
351 | return (error); | |
352 | } | |
353 | ||
354 | struct xattr_handler zpl_xattr_trusted_handler = { | |
355 | .prefix = XATTR_TRUSTED_PREFIX, | |
356 | .get = zpl_xattr_trusted_get, | |
357 | .set = zpl_xattr_trusted_set, | |
358 | }; | |
359 | ||
360 | static int | |
361 | zpl_xattr_security_get(struct inode *ip, const char *name, | |
362 | void *buffer, size_t size) | |
363 | { | |
364 | char *xattr_name; | |
365 | int error; | |
366 | ||
367 | if (strcmp(name, "") == 0) | |
368 | return -EINVAL; | |
369 | ||
370 | xattr_name = kmem_asprintf("%s%s", XATTR_SECURITY_PREFIX, name); | |
371 | error = zpl_xattr_get(ip, xattr_name, buffer, size); | |
372 | strfree(xattr_name); | |
373 | ||
374 | return (error); | |
375 | } | |
376 | ||
377 | static int | |
378 | zpl_xattr_security_set(struct inode *ip, const char *name, | |
379 | const void *value, size_t size, int flags) | |
380 | { | |
381 | char *xattr_name; | |
382 | int error; | |
383 | ||
384 | if (strcmp(name, "") == 0) | |
385 | return -EINVAL; | |
386 | ||
387 | xattr_name = kmem_asprintf("%s%s", XATTR_SECURITY_PREFIX, name); | |
388 | error = zpl_xattr_set(ip, xattr_name, value, size, flags); | |
389 | strfree(xattr_name); | |
390 | ||
391 | return (error); | |
392 | } | |
393 | ||
394 | int | |
395 | zpl_xattr_security_init(struct inode *ip, struct inode *dip) | |
396 | { | |
397 | int error; | |
398 | size_t len; | |
399 | void *value; | |
400 | char *name; | |
401 | ||
402 | error = security_inode_init_security(ip, dip, &name, &value, &len); | |
403 | if (error) { | |
404 | if (error == -EOPNOTSUPP) | |
405 | return 0; | |
406 | ||
407 | return (error); | |
408 | } | |
409 | ||
410 | error = zpl_xattr_security_set(ip, name, value, len, 0); | |
411 | ||
412 | kfree(name); | |
413 | kfree(value); | |
414 | ||
415 | return (error); | |
416 | } | |
417 | ||
418 | struct xattr_handler zpl_xattr_security_handler = { | |
419 | .prefix = XATTR_SECURITY_PREFIX, | |
420 | .get = zpl_xattr_security_get, | |
421 | .set = zpl_xattr_security_set, | |
422 | }; | |
423 | ||
424 | struct xattr_handler *zpl_xattr_handlers[] = { | |
425 | &zpl_xattr_security_handler, | |
426 | &zpl_xattr_trusted_handler, | |
427 | &zpl_xattr_user_handler, | |
428 | #ifdef HAVE_POSIX_ACLS | |
429 | &zpl_xattr_acl_access_handler, | |
430 | &zpl_xattr_acl_default_handler, | |
431 | #endif /* HAVE_POSIX_ACLS */ | |
432 | }; |