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