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 | ||
1da177e4 LT |
118 | /* |
119 | * For sys_getproccap() and sys_setproccap(), any of the three | |
120 | * capability set pointers may be NULL -- indicating that that set is | |
121 | * uninteresting and/or not to be changed. | |
122 | */ | |
123 | ||
086f7316 AM |
124 | /* |
125 | * Atomically modify the effective capabilities returning the original | |
126 | * value. No permission check is performed here - it is assumed that the | |
127 | * caller is permitted to set the desired effective capabilities. | |
128 | */ | |
129 | kernel_cap_t cap_set_effective(const kernel_cap_t pE_new) | |
130 | { | |
131 | kernel_cap_t pE_old; | |
132 | ||
133 | spin_lock(&task_capability_lock); | |
134 | ||
135 | pE_old = current->cap_effective; | |
136 | current->cap_effective = pE_new; | |
137 | ||
138 | spin_unlock(&task_capability_lock); | |
139 | ||
140 | return pE_old; | |
141 | } | |
142 | ||
143 | EXPORT_SYMBOL(cap_set_effective); | |
144 | ||
207a7ba8 | 145 | /** |
1da177e4 | 146 | * sys_capget - get the capabilities of a given process. |
207a7ba8 RD |
147 | * @header: pointer to struct that contains capability version and |
148 | * target pid data | |
149 | * @dataptr: pointer to struct that contains the effective, permitted, | |
150 | * and inheritable capabilities that are returned | |
151 | * | |
152 | * Returns 0 on success and < 0 on error. | |
1da177e4 LT |
153 | */ |
154 | asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr) | |
155 | { | |
314f70fd DW |
156 | int ret = 0; |
157 | pid_t pid; | |
314f70fd | 158 | struct task_struct *target; |
e338d263 AM |
159 | unsigned tocopy; |
160 | kernel_cap_t pE, pI, pP; | |
314f70fd | 161 | |
ca05a99a AM |
162 | ret = cap_validate_magic(header, &tocopy); |
163 | if (ret != 0) | |
164 | return ret; | |
1da177e4 | 165 | |
314f70fd DW |
166 | if (get_user(pid, &header->pid)) |
167 | return -EFAULT; | |
1da177e4 | 168 | |
314f70fd DW |
169 | if (pid < 0) |
170 | return -EINVAL; | |
1da177e4 | 171 | |
314f70fd DW |
172 | spin_lock(&task_capability_lock); |
173 | read_lock(&tasklist_lock); | |
1da177e4 | 174 | |
b488893a | 175 | if (pid && pid != task_pid_vnr(current)) { |
228ebcbe | 176 | target = find_task_by_vpid(pid); |
314f70fd DW |
177 | if (!target) { |
178 | ret = -ESRCH; | |
179 | goto out; | |
180 | } | |
181 | } else | |
182 | target = current; | |
1da177e4 | 183 | |
e338d263 | 184 | ret = security_capget(target, &pE, &pI, &pP); |
1da177e4 LT |
185 | |
186 | out: | |
314f70fd DW |
187 | read_unlock(&tasklist_lock); |
188 | spin_unlock(&task_capability_lock); | |
1da177e4 | 189 | |
e338d263 | 190 | if (!ret) { |
ca05a99a | 191 | struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S]; |
e338d263 AM |
192 | unsigned i; |
193 | ||
194 | for (i = 0; i < tocopy; i++) { | |
195 | kdata[i].effective = pE.cap[i]; | |
196 | kdata[i].permitted = pP.cap[i]; | |
197 | kdata[i].inheritable = pI.cap[i]; | |
198 | } | |
199 | ||
200 | /* | |
ca05a99a | 201 | * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S, |
e338d263 AM |
202 | * we silently drop the upper capabilities here. This |
203 | * has the effect of making older libcap | |
204 | * implementations implicitly drop upper capability | |
205 | * bits when they perform a: capget/modify/capset | |
206 | * sequence. | |
207 | * | |
208 | * This behavior is considered fail-safe | |
209 | * behavior. Upgrading the application to a newer | |
210 | * version of libcap will enable access to the newer | |
211 | * capabilities. | |
212 | * | |
213 | * An alternative would be to return an error here | |
214 | * (-ERANGE), but that causes legacy applications to | |
215 | * unexpectidly fail; the capget/modify/capset aborts | |
216 | * before modification is attempted and the application | |
217 | * fails. | |
218 | */ | |
219 | ||
220 | if (copy_to_user(dataptr, kdata, tocopy | |
221 | * sizeof(struct __user_cap_data_struct))) { | |
222 | return -EFAULT; | |
223 | } | |
224 | } | |
1da177e4 | 225 | |
314f70fd | 226 | return ret; |
1da177e4 LT |
227 | } |
228 | ||
229 | /* | |
230 | * cap_set_pg - set capabilities for all processes in a given process | |
231 | * group. We call this holding task_capability_lock and tasklist_lock. | |
232 | */ | |
41487c65 | 233 | static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective, |
1da177e4 LT |
234 | kernel_cap_t *inheritable, |
235 | kernel_cap_t *permitted) | |
236 | { | |
36c8b586 | 237 | struct task_struct *g, *target; |
1da177e4 LT |
238 | int ret = -EPERM; |
239 | int found = 0; | |
41487c65 | 240 | struct pid *pgrp; |
1da177e4 | 241 | |
8990571e | 242 | pgrp = find_vpid(pgrp_nr); |
41487c65 | 243 | do_each_pid_task(pgrp, PIDTYPE_PGID, g) { |
1da177e4 LT |
244 | target = g; |
245 | while_each_thread(g, target) { | |
246 | if (!security_capset_check(target, effective, | |
247 | inheritable, | |
248 | permitted)) { | |
249 | security_capset_set(target, effective, | |
250 | inheritable, | |
251 | permitted); | |
252 | ret = 0; | |
253 | } | |
254 | found = 1; | |
255 | } | |
41487c65 | 256 | } while_each_pid_task(pgrp, PIDTYPE_PGID, g); |
1da177e4 LT |
257 | |
258 | if (!found) | |
314f70fd | 259 | ret = 0; |
1da177e4 LT |
260 | return ret; |
261 | } | |
262 | ||
263 | /* | |
264 | * cap_set_all - set capabilities for all processes other than init | |
265 | * and self. We call this holding task_capability_lock and tasklist_lock. | |
266 | */ | |
267 | static inline int cap_set_all(kernel_cap_t *effective, | |
268 | kernel_cap_t *inheritable, | |
269 | kernel_cap_t *permitted) | |
270 | { | |
36c8b586 | 271 | struct task_struct *g, *target; |
1da177e4 LT |
272 | int ret = -EPERM; |
273 | int found = 0; | |
274 | ||
275 | do_each_thread(g, target) { | |
b460cbc5 | 276 | if (target == current || is_container_init(target->group_leader)) |
1da177e4 LT |
277 | continue; |
278 | found = 1; | |
279 | if (security_capset_check(target, effective, inheritable, | |
280 | permitted)) | |
281 | continue; | |
282 | ret = 0; | |
283 | security_capset_set(target, effective, inheritable, permitted); | |
284 | } while_each_thread(g, target); | |
285 | ||
286 | if (!found) | |
287 | ret = 0; | |
288 | return ret; | |
289 | } | |
290 | ||
207a7ba8 RD |
291 | /** |
292 | * sys_capset - set capabilities for a process or a group of processes | |
293 | * @header: pointer to struct that contains capability version and | |
294 | * target pid data | |
295 | * @data: pointer to struct that contains the effective, permitted, | |
296 | * and inheritable capabilities | |
297 | * | |
298 | * Set capabilities for a given process, all processes, or all | |
1da177e4 LT |
299 | * processes in a given process group. |
300 | * | |
301 | * The restrictions on setting capabilities are specified as: | |
302 | * | |
303 | * [pid is for the 'target' task. 'current' is the calling task.] | |
304 | * | |
305 | * I: any raised capabilities must be a subset of the (old current) permitted | |
306 | * P: any raised capabilities must be a subset of the (old current) permitted | |
307 | * E: must be set to a subset of (new target) permitted | |
207a7ba8 RD |
308 | * |
309 | * Returns 0 on success and < 0 on error. | |
1da177e4 LT |
310 | */ |
311 | asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data) | |
312 | { | |
ca05a99a | 313 | struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S]; |
e338d263 | 314 | unsigned i, tocopy; |
314f70fd | 315 | kernel_cap_t inheritable, permitted, effective; |
314f70fd DW |
316 | struct task_struct *target; |
317 | int ret; | |
318 | pid_t pid; | |
319 | ||
ca05a99a AM |
320 | ret = cap_validate_magic(header, &tocopy); |
321 | if (ret != 0) | |
322 | return ret; | |
314f70fd DW |
323 | |
324 | if (get_user(pid, &header->pid)) | |
325 | return -EFAULT; | |
326 | ||
b488893a | 327 | if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP)) |
314f70fd DW |
328 | return -EPERM; |
329 | ||
e338d263 AM |
330 | if (copy_from_user(&kdata, data, tocopy |
331 | * sizeof(struct __user_cap_data_struct))) { | |
314f70fd | 332 | return -EFAULT; |
e338d263 AM |
333 | } |
334 | ||
335 | for (i = 0; i < tocopy; i++) { | |
336 | effective.cap[i] = kdata[i].effective; | |
337 | permitted.cap[i] = kdata[i].permitted; | |
338 | inheritable.cap[i] = kdata[i].inheritable; | |
339 | } | |
ca05a99a | 340 | while (i < _KERNEL_CAPABILITY_U32S) { |
e338d263 AM |
341 | effective.cap[i] = 0; |
342 | permitted.cap[i] = 0; | |
343 | inheritable.cap[i] = 0; | |
344 | i++; | |
345 | } | |
314f70fd DW |
346 | |
347 | spin_lock(&task_capability_lock); | |
348 | read_lock(&tasklist_lock); | |
349 | ||
b488893a | 350 | if (pid > 0 && pid != task_pid_vnr(current)) { |
228ebcbe | 351 | target = find_task_by_vpid(pid); |
314f70fd DW |
352 | if (!target) { |
353 | ret = -ESRCH; | |
354 | goto out; | |
355 | } | |
356 | } else | |
357 | target = current; | |
358 | ||
359 | ret = 0; | |
360 | ||
361 | /* having verified that the proposed changes are legal, | |
362 | we now put them into effect. */ | |
363 | if (pid < 0) { | |
364 | if (pid == -1) /* all procs other than current and init */ | |
365 | ret = cap_set_all(&effective, &inheritable, &permitted); | |
366 | ||
367 | else /* all procs in process group */ | |
368 | ret = cap_set_pg(-pid, &effective, &inheritable, | |
369 | &permitted); | |
370 | } else { | |
371 | ret = security_capset_check(target, &effective, &inheritable, | |
372 | &permitted); | |
373 | if (!ret) | |
374 | security_capset_set(target, &effective, &inheritable, | |
375 | &permitted); | |
376 | } | |
1da177e4 LT |
377 | |
378 | out: | |
314f70fd DW |
379 | read_unlock(&tasklist_lock); |
380 | spin_unlock(&task_capability_lock); | |
1da177e4 | 381 | |
314f70fd | 382 | return ret; |
1da177e4 | 383 | } |
12b5989b CW |
384 | |
385 | int __capable(struct task_struct *t, int cap) | |
386 | { | |
387 | if (security_capable(t, cap) == 0) { | |
388 | t->flags |= PF_SUPERPRIV; | |
389 | return 1; | |
390 | } | |
391 | return 0; | |
392 | } | |
12b5989b CW |
393 | |
394 | int capable(int cap) | |
395 | { | |
396 | return __capable(current, cap); | |
397 | } | |
398 | EXPORT_SYMBOL(capable); |