Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/capability.c | |
3 | * | |
4 | * Copyright (C) 1997 Andrew Main <zefram@fysh.org> | |
5 | * | |
72c2d582 | 6 | * Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org> |
1da177e4 | 7 | * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net> |
314f70fd | 8 | */ |
1da177e4 | 9 | |
e68b75a0 | 10 | #include <linux/audit.h> |
c59ede7b | 11 | #include <linux/capability.h> |
1da177e4 LT |
12 | #include <linux/mm.h> |
13 | #include <linux/module.h> | |
14 | #include <linux/security.h> | |
15 | #include <linux/syscalls.h> | |
b460cbc5 | 16 | #include <linux/pid_namespace.h> |
1da177e4 LT |
17 | #include <asm/uaccess.h> |
18 | ||
1da177e4 LT |
19 | /* |
20 | * This lock protects task->cap_* for all tasks including current. | |
21 | * Locking rule: acquire this prior to tasklist_lock. | |
22 | */ | |
23 | static DEFINE_SPINLOCK(task_capability_lock); | |
24 | ||
e338d263 AM |
25 | /* |
26 | * Leveraged for setting/resetting capabilities | |
27 | */ | |
28 | ||
29 | const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET; | |
30 | const kernel_cap_t __cap_full_set = CAP_FULL_SET; | |
31 | const kernel_cap_t __cap_init_eff_set = CAP_INIT_EFF_SET; | |
32 | ||
33 | EXPORT_SYMBOL(__cap_empty_set); | |
34 | EXPORT_SYMBOL(__cap_full_set); | |
35 | EXPORT_SYMBOL(__cap_init_eff_set); | |
36 | ||
1f29fae2 SH |
37 | #ifdef CONFIG_SECURITY_FILE_CAPABILITIES |
38 | int file_caps_enabled = 1; | |
39 | ||
40 | static int __init file_caps_disable(char *str) | |
41 | { | |
42 | file_caps_enabled = 0; | |
43 | return 1; | |
44 | } | |
45 | __setup("no_file_caps", file_caps_disable); | |
46 | #endif | |
47 | ||
e338d263 AM |
48 | /* |
49 | * More recent versions of libcap are available from: | |
50 | * | |
51 | * http://www.kernel.org/pub/linux/libs/security/linux-privs/ | |
52 | */ | |
53 | ||
54 | static void warn_legacy_capability_use(void) | |
55 | { | |
56 | static int warned; | |
57 | if (!warned) { | |
58 | char name[sizeof(current->comm)]; | |
59 | ||
60 | printk(KERN_INFO "warning: `%s' uses 32-bit capabilities" | |
61 | " (legacy support in use)\n", | |
62 | get_task_comm(name, current)); | |
63 | warned = 1; | |
64 | } | |
65 | } | |
66 | ||
ca05a99a AM |
67 | /* |
68 | * Version 2 capabilities worked fine, but the linux/capability.h file | |
69 | * that accompanied their introduction encouraged their use without | |
70 | * the necessary user-space source code changes. As such, we have | |
71 | * created a version 3 with equivalent functionality to version 2, but | |
72 | * with a header change to protect legacy source code from using | |
73 | * version 2 when it wanted to use version 1. If your system has code | |
74 | * that trips the following warning, it is using version 2 specific | |
75 | * capabilities and may be doing so insecurely. | |
76 | * | |
77 | * The remedy is to either upgrade your version of libcap (to 2.10+, | |
78 | * if the application is linked against it), or recompile your | |
79 | * application with modern kernel headers and this warning will go | |
80 | * away. | |
81 | */ | |
82 | ||
83 | static void warn_deprecated_v2(void) | |
84 | { | |
85 | static int warned; | |
86 | ||
87 | if (!warned) { | |
88 | char name[sizeof(current->comm)]; | |
89 | ||
90 | printk(KERN_INFO "warning: `%s' uses deprecated v2" | |
91 | " capabilities in a way that may be insecure.\n", | |
92 | get_task_comm(name, current)); | |
93 | warned = 1; | |
94 | } | |
95 | } | |
96 | ||
97 | /* | |
98 | * Version check. Return the number of u32s in each capability flag | |
99 | * array, or a negative value on error. | |
100 | */ | |
101 | static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy) | |
102 | { | |
103 | __u32 version; | |
104 | ||
105 | if (get_user(version, &header->version)) | |
106 | return -EFAULT; | |
107 | ||
108 | switch (version) { | |
109 | case _LINUX_CAPABILITY_VERSION_1: | |
110 | warn_legacy_capability_use(); | |
111 | *tocopy = _LINUX_CAPABILITY_U32S_1; | |
112 | break; | |
113 | case _LINUX_CAPABILITY_VERSION_2: | |
114 | warn_deprecated_v2(); | |
115 | /* | |
116 | * fall through - v3 is otherwise equivalent to v2. | |
117 | */ | |
118 | case _LINUX_CAPABILITY_VERSION_3: | |
119 | *tocopy = _LINUX_CAPABILITY_U32S_3; | |
120 | break; | |
121 | default: | |
122 | if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version)) | |
123 | return -EFAULT; | |
124 | return -EINVAL; | |
125 | } | |
126 | ||
127 | return 0; | |
128 | } | |
129 | ||
ab763c71 AM |
130 | #ifndef CONFIG_SECURITY_FILE_CAPABILITIES |
131 | ||
132 | /* | |
133 | * Without filesystem capability support, we nominally support one process | |
134 | * setting the capabilities of another | |
135 | */ | |
136 | static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp, | |
137 | kernel_cap_t *pIp, kernel_cap_t *pPp) | |
138 | { | |
139 | struct task_struct *target; | |
140 | int ret; | |
141 | ||
142 | spin_lock(&task_capability_lock); | |
143 | read_lock(&tasklist_lock); | |
144 | ||
145 | if (pid && pid != task_pid_vnr(current)) { | |
146 | target = find_task_by_vpid(pid); | |
147 | if (!target) { | |
148 | ret = -ESRCH; | |
149 | goto out; | |
150 | } | |
151 | } else | |
152 | target = current; | |
153 | ||
154 | ret = security_capget(target, pEp, pIp, pPp); | |
155 | ||
156 | out: | |
157 | read_unlock(&tasklist_lock); | |
158 | spin_unlock(&task_capability_lock); | |
159 | ||
160 | return ret; | |
161 | } | |
162 | ||
163 | /* | |
164 | * cap_set_pg - set capabilities for all processes in a given process | |
165 | * group. We call this holding task_capability_lock and tasklist_lock. | |
166 | */ | |
167 | static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective, | |
168 | kernel_cap_t *inheritable, | |
169 | kernel_cap_t *permitted) | |
170 | { | |
171 | struct task_struct *g, *target; | |
172 | int ret = -EPERM; | |
173 | int found = 0; | |
174 | struct pid *pgrp; | |
175 | ||
176 | spin_lock(&task_capability_lock); | |
177 | read_lock(&tasklist_lock); | |
178 | ||
179 | pgrp = find_vpid(pgrp_nr); | |
180 | do_each_pid_task(pgrp, PIDTYPE_PGID, g) { | |
181 | target = g; | |
182 | while_each_thread(g, target) { | |
183 | if (!security_capset_check(target, effective, | |
184 | inheritable, permitted)) { | |
185 | security_capset_set(target, effective, | |
186 | inheritable, permitted); | |
187 | ret = 0; | |
188 | } | |
189 | found = 1; | |
190 | } | |
191 | } while_each_pid_task(pgrp, PIDTYPE_PGID, g); | |
192 | ||
193 | read_unlock(&tasklist_lock); | |
194 | spin_unlock(&task_capability_lock); | |
195 | ||
196 | if (!found) | |
197 | ret = 0; | |
198 | return ret; | |
199 | } | |
200 | ||
1da177e4 | 201 | /* |
ab763c71 AM |
202 | * cap_set_all - set capabilities for all processes other than init |
203 | * and self. We call this holding task_capability_lock and tasklist_lock. | |
1da177e4 | 204 | */ |
ab763c71 AM |
205 | static inline int cap_set_all(kernel_cap_t *effective, |
206 | kernel_cap_t *inheritable, | |
207 | kernel_cap_t *permitted) | |
208 | { | |
209 | struct task_struct *g, *target; | |
210 | int ret = -EPERM; | |
211 | int found = 0; | |
212 | ||
213 | spin_lock(&task_capability_lock); | |
214 | read_lock(&tasklist_lock); | |
215 | ||
216 | do_each_thread(g, target) { | |
217 | if (target == current | |
218 | || is_container_init(target->group_leader)) | |
219 | continue; | |
220 | found = 1; | |
221 | if (security_capset_check(target, effective, inheritable, | |
222 | permitted)) | |
223 | continue; | |
224 | ret = 0; | |
225 | security_capset_set(target, effective, inheritable, permitted); | |
226 | } while_each_thread(g, target); | |
227 | ||
228 | read_unlock(&tasklist_lock); | |
229 | spin_unlock(&task_capability_lock); | |
230 | ||
231 | if (!found) | |
232 | ret = 0; | |
233 | ||
234 | return ret; | |
235 | } | |
236 | ||
237 | /* | |
238 | * Given the target pid does not refer to the current process we | |
239 | * need more elaborate support... (This support is not present when | |
240 | * filesystem capabilities are configured.) | |
241 | */ | |
242 | static inline int do_sys_capset_other_tasks(pid_t pid, kernel_cap_t *effective, | |
243 | kernel_cap_t *inheritable, | |
244 | kernel_cap_t *permitted) | |
245 | { | |
246 | struct task_struct *target; | |
247 | int ret; | |
248 | ||
249 | if (!capable(CAP_SETPCAP)) | |
250 | return -EPERM; | |
251 | ||
252 | if (pid == -1) /* all procs other than current and init */ | |
253 | return cap_set_all(effective, inheritable, permitted); | |
254 | ||
255 | else if (pid < 0) /* all procs in process group */ | |
256 | return cap_set_pg(-pid, effective, inheritable, permitted); | |
257 | ||
258 | /* target != current */ | |
259 | spin_lock(&task_capability_lock); | |
260 | read_lock(&tasklist_lock); | |
261 | ||
262 | target = find_task_by_vpid(pid); | |
263 | if (!target) | |
264 | ret = -ESRCH; | |
265 | else { | |
266 | ret = security_capset_check(target, effective, inheritable, | |
267 | permitted); | |
268 | ||
269 | /* having verified that the proposed changes are legal, | |
270 | we now put them into effect. */ | |
271 | if (!ret) | |
272 | security_capset_set(target, effective, inheritable, | |
273 | permitted); | |
274 | } | |
275 | ||
276 | read_unlock(&tasklist_lock); | |
277 | spin_unlock(&task_capability_lock); | |
278 | ||
279 | return ret; | |
280 | } | |
281 | ||
282 | #else /* ie., def CONFIG_SECURITY_FILE_CAPABILITIES */ | |
283 | ||
284 | /* | |
285 | * If we have configured with filesystem capability support, then the | |
286 | * only thing that can change the capabilities of the current process | |
287 | * is the current process. As such, we can't be in this code at the | |
288 | * same time as we are in the process of setting capabilities in this | |
289 | * process. The net result is that we can limit our use of locks to | |
290 | * when we are reading the caps of another process. | |
291 | */ | |
292 | static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp, | |
293 | kernel_cap_t *pIp, kernel_cap_t *pPp) | |
294 | { | |
295 | int ret; | |
296 | ||
297 | if (pid && (pid != task_pid_vnr(current))) { | |
298 | struct task_struct *target; | |
299 | ||
300 | spin_lock(&task_capability_lock); | |
301 | read_lock(&tasklist_lock); | |
302 | ||
303 | target = find_task_by_vpid(pid); | |
304 | if (!target) | |
305 | ret = -ESRCH; | |
306 | else | |
307 | ret = security_capget(target, pEp, pIp, pPp); | |
308 | ||
309 | read_unlock(&tasklist_lock); | |
310 | spin_unlock(&task_capability_lock); | |
311 | } else | |
312 | ret = security_capget(current, pEp, pIp, pPp); | |
313 | ||
314 | return ret; | |
315 | } | |
316 | ||
317 | /* | |
318 | * With filesystem capability support configured, the kernel does not | |
319 | * permit the changing of capabilities in one process by another | |
320 | * process. (CAP_SETPCAP has much less broad semantics when configured | |
321 | * this way.) | |
322 | */ | |
323 | static inline int do_sys_capset_other_tasks(pid_t pid, | |
324 | kernel_cap_t *effective, | |
325 | kernel_cap_t *inheritable, | |
326 | kernel_cap_t *permitted) | |
327 | { | |
328 | return -EPERM; | |
329 | } | |
330 | ||
331 | #endif /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */ | |
1da177e4 | 332 | |
086f7316 AM |
333 | /* |
334 | * Atomically modify the effective capabilities returning the original | |
335 | * value. No permission check is performed here - it is assumed that the | |
336 | * caller is permitted to set the desired effective capabilities. | |
337 | */ | |
338 | kernel_cap_t cap_set_effective(const kernel_cap_t pE_new) | |
339 | { | |
340 | kernel_cap_t pE_old; | |
341 | ||
342 | spin_lock(&task_capability_lock); | |
343 | ||
344 | pE_old = current->cap_effective; | |
345 | current->cap_effective = pE_new; | |
346 | ||
347 | spin_unlock(&task_capability_lock); | |
348 | ||
349 | return pE_old; | |
350 | } | |
351 | ||
352 | EXPORT_SYMBOL(cap_set_effective); | |
353 | ||
207a7ba8 | 354 | /** |
1da177e4 | 355 | * sys_capget - get the capabilities of a given process. |
207a7ba8 RD |
356 | * @header: pointer to struct that contains capability version and |
357 | * target pid data | |
358 | * @dataptr: pointer to struct that contains the effective, permitted, | |
359 | * and inheritable capabilities that are returned | |
360 | * | |
361 | * Returns 0 on success and < 0 on error. | |
1da177e4 LT |
362 | */ |
363 | asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr) | |
364 | { | |
314f70fd DW |
365 | int ret = 0; |
366 | pid_t pid; | |
e338d263 AM |
367 | unsigned tocopy; |
368 | kernel_cap_t pE, pI, pP; | |
314f70fd | 369 | |
ca05a99a AM |
370 | ret = cap_validate_magic(header, &tocopy); |
371 | if (ret != 0) | |
372 | return ret; | |
1da177e4 | 373 | |
314f70fd DW |
374 | if (get_user(pid, &header->pid)) |
375 | return -EFAULT; | |
1da177e4 | 376 | |
314f70fd DW |
377 | if (pid < 0) |
378 | return -EINVAL; | |
1da177e4 | 379 | |
ab763c71 | 380 | ret = cap_get_target_pid(pid, &pE, &pI, &pP); |
1da177e4 | 381 | |
e338d263 | 382 | if (!ret) { |
ca05a99a | 383 | struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S]; |
e338d263 AM |
384 | unsigned i; |
385 | ||
386 | for (i = 0; i < tocopy; i++) { | |
387 | kdata[i].effective = pE.cap[i]; | |
388 | kdata[i].permitted = pP.cap[i]; | |
389 | kdata[i].inheritable = pI.cap[i]; | |
390 | } | |
391 | ||
392 | /* | |
ca05a99a | 393 | * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S, |
e338d263 AM |
394 | * we silently drop the upper capabilities here. This |
395 | * has the effect of making older libcap | |
396 | * implementations implicitly drop upper capability | |
397 | * bits when they perform a: capget/modify/capset | |
398 | * sequence. | |
399 | * | |
400 | * This behavior is considered fail-safe | |
401 | * behavior. Upgrading the application to a newer | |
402 | * version of libcap will enable access to the newer | |
403 | * capabilities. | |
404 | * | |
405 | * An alternative would be to return an error here | |
406 | * (-ERANGE), but that causes legacy applications to | |
407 | * unexpectidly fail; the capget/modify/capset aborts | |
408 | * before modification is attempted and the application | |
409 | * fails. | |
410 | */ | |
e338d263 AM |
411 | if (copy_to_user(dataptr, kdata, tocopy |
412 | * sizeof(struct __user_cap_data_struct))) { | |
413 | return -EFAULT; | |
414 | } | |
415 | } | |
1da177e4 | 416 | |
314f70fd | 417 | return ret; |
1da177e4 LT |
418 | } |
419 | ||
207a7ba8 | 420 | /** |
ab763c71 | 421 | * sys_capset - set capabilities for a process or (*) a group of processes |
207a7ba8 RD |
422 | * @header: pointer to struct that contains capability version and |
423 | * target pid data | |
424 | * @data: pointer to struct that contains the effective, permitted, | |
425 | * and inheritable capabilities | |
426 | * | |
427 | * Set capabilities for a given process, all processes, or all | |
1da177e4 LT |
428 | * processes in a given process group. |
429 | * | |
430 | * The restrictions on setting capabilities are specified as: | |
431 | * | |
432 | * [pid is for the 'target' task. 'current' is the calling task.] | |
433 | * | |
434 | * I: any raised capabilities must be a subset of the (old current) permitted | |
435 | * P: any raised capabilities must be a subset of the (old current) permitted | |
436 | * E: must be set to a subset of (new target) permitted | |
207a7ba8 RD |
437 | * |
438 | * Returns 0 on success and < 0 on error. | |
1da177e4 LT |
439 | */ |
440 | asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data) | |
441 | { | |
ca05a99a | 442 | struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S]; |
e338d263 | 443 | unsigned i, tocopy; |
314f70fd | 444 | kernel_cap_t inheritable, permitted, effective; |
314f70fd DW |
445 | int ret; |
446 | pid_t pid; | |
447 | ||
ca05a99a AM |
448 | ret = cap_validate_magic(header, &tocopy); |
449 | if (ret != 0) | |
450 | return ret; | |
314f70fd DW |
451 | |
452 | if (get_user(pid, &header->pid)) | |
453 | return -EFAULT; | |
454 | ||
e338d263 AM |
455 | if (copy_from_user(&kdata, data, tocopy |
456 | * sizeof(struct __user_cap_data_struct))) { | |
314f70fd | 457 | return -EFAULT; |
e338d263 AM |
458 | } |
459 | ||
460 | for (i = 0; i < tocopy; i++) { | |
461 | effective.cap[i] = kdata[i].effective; | |
462 | permitted.cap[i] = kdata[i].permitted; | |
463 | inheritable.cap[i] = kdata[i].inheritable; | |
464 | } | |
ca05a99a | 465 | while (i < _KERNEL_CAPABILITY_U32S) { |
e338d263 AM |
466 | effective.cap[i] = 0; |
467 | permitted.cap[i] = 0; | |
468 | inheritable.cap[i] = 0; | |
469 | i++; | |
470 | } | |
314f70fd | 471 | |
e68b75a0 EP |
472 | ret = audit_log_capset(pid, &effective, &inheritable, &permitted); |
473 | if (ret) | |
474 | return ret; | |
475 | ||
ab763c71 AM |
476 | if (pid && (pid != task_pid_vnr(current))) |
477 | ret = do_sys_capset_other_tasks(pid, &effective, &inheritable, | |
478 | &permitted); | |
479 | else { | |
480 | /* | |
481 | * This lock is required even when filesystem | |
482 | * capability support is configured - it protects the | |
483 | * sys_capget() call from returning incorrect data in | |
484 | * the case that the targeted process is not the | |
485 | * current one. | |
486 | */ | |
487 | spin_lock(&task_capability_lock); | |
314f70fd | 488 | |
ab763c71 | 489 | ret = security_capset_check(current, &effective, &inheritable, |
314f70fd | 490 | &permitted); |
ab763c71 AM |
491 | /* |
492 | * Having verified that the proposed changes are | |
493 | * legal, we now put them into effect. | |
494 | */ | |
314f70fd | 495 | if (!ret) |
ab763c71 | 496 | security_capset_set(current, &effective, &inheritable, |
314f70fd | 497 | &permitted); |
ab763c71 | 498 | spin_unlock(&task_capability_lock); |
314f70fd | 499 | } |
1da177e4 | 500 | |
1da177e4 | 501 | |
314f70fd | 502 | return ret; |
1da177e4 | 503 | } |
12b5989b | 504 | |
5cd9c58f DH |
505 | /** |
506 | * capable - Determine if the current task has a superior capability in effect | |
507 | * @cap: The capability to be tested for | |
508 | * | |
509 | * Return true if the current task has the given superior capability currently | |
510 | * available for use, false if not. | |
511 | * | |
512 | * This sets PF_SUPERPRIV on the task if the capability is available on the | |
513 | * assumption that it's about to be used. | |
514 | */ | |
515 | int capable(int cap) | |
12b5989b | 516 | { |
5cd9c58f DH |
517 | if (has_capability(current, cap)) { |
518 | current->flags |= PF_SUPERPRIV; | |
12b5989b CW |
519 | return 1; |
520 | } | |
521 | return 0; | |
522 | } | |
12b5989b | 523 | EXPORT_SYMBOL(capable); |