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 | ||
1da177e4 LT |
55 | /* |
56 | * For sys_getproccap() and sys_setproccap(), any of the three | |
57 | * capability set pointers may be NULL -- indicating that that set is | |
58 | * uninteresting and/or not to be changed. | |
59 | */ | |
60 | ||
207a7ba8 | 61 | /** |
1da177e4 | 62 | * sys_capget - get the capabilities of a given process. |
207a7ba8 RD |
63 | * @header: pointer to struct that contains capability version and |
64 | * target pid data | |
65 | * @dataptr: pointer to struct that contains the effective, permitted, | |
66 | * and inheritable capabilities that are returned | |
67 | * | |
68 | * Returns 0 on success and < 0 on error. | |
1da177e4 LT |
69 | */ |
70 | asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr) | |
71 | { | |
314f70fd DW |
72 | int ret = 0; |
73 | pid_t pid; | |
74 | __u32 version; | |
75 | struct task_struct *target; | |
e338d263 AM |
76 | unsigned tocopy; |
77 | kernel_cap_t pE, pI, pP; | |
314f70fd DW |
78 | |
79 | if (get_user(version, &header->version)) | |
80 | return -EFAULT; | |
81 | ||
e338d263 AM |
82 | switch (version) { |
83 | case _LINUX_CAPABILITY_VERSION_1: | |
84 | warn_legacy_capability_use(); | |
85 | tocopy = _LINUX_CAPABILITY_U32S_1; | |
86 | break; | |
87 | case _LINUX_CAPABILITY_VERSION_2: | |
88 | tocopy = _LINUX_CAPABILITY_U32S_2; | |
89 | break; | |
90 | default: | |
314f70fd DW |
91 | if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) |
92 | return -EFAULT; | |
93 | return -EINVAL; | |
94 | } | |
1da177e4 | 95 | |
314f70fd DW |
96 | if (get_user(pid, &header->pid)) |
97 | return -EFAULT; | |
1da177e4 | 98 | |
314f70fd DW |
99 | if (pid < 0) |
100 | return -EINVAL; | |
1da177e4 | 101 | |
314f70fd DW |
102 | spin_lock(&task_capability_lock); |
103 | read_lock(&tasklist_lock); | |
1da177e4 | 104 | |
b488893a | 105 | if (pid && pid != task_pid_vnr(current)) { |
228ebcbe | 106 | target = find_task_by_vpid(pid); |
314f70fd DW |
107 | if (!target) { |
108 | ret = -ESRCH; | |
109 | goto out; | |
110 | } | |
111 | } else | |
112 | target = current; | |
1da177e4 | 113 | |
e338d263 | 114 | ret = security_capget(target, &pE, &pI, &pP); |
1da177e4 LT |
115 | |
116 | out: | |
314f70fd DW |
117 | read_unlock(&tasklist_lock); |
118 | spin_unlock(&task_capability_lock); | |
1da177e4 | 119 | |
e338d263 AM |
120 | if (!ret) { |
121 | struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S]; | |
122 | unsigned i; | |
123 | ||
124 | for (i = 0; i < tocopy; i++) { | |
125 | kdata[i].effective = pE.cap[i]; | |
126 | kdata[i].permitted = pP.cap[i]; | |
127 | kdata[i].inheritable = pI.cap[i]; | |
128 | } | |
129 | ||
130 | /* | |
131 | * Note, in the case, tocopy < _LINUX_CAPABILITY_U32S, | |
132 | * we silently drop the upper capabilities here. This | |
133 | * has the effect of making older libcap | |
134 | * implementations implicitly drop upper capability | |
135 | * bits when they perform a: capget/modify/capset | |
136 | * sequence. | |
137 | * | |
138 | * This behavior is considered fail-safe | |
139 | * behavior. Upgrading the application to a newer | |
140 | * version of libcap will enable access to the newer | |
141 | * capabilities. | |
142 | * | |
143 | * An alternative would be to return an error here | |
144 | * (-ERANGE), but that causes legacy applications to | |
145 | * unexpectidly fail; the capget/modify/capset aborts | |
146 | * before modification is attempted and the application | |
147 | * fails. | |
148 | */ | |
149 | ||
150 | if (copy_to_user(dataptr, kdata, tocopy | |
151 | * sizeof(struct __user_cap_data_struct))) { | |
152 | return -EFAULT; | |
153 | } | |
154 | } | |
1da177e4 | 155 | |
314f70fd | 156 | return ret; |
1da177e4 LT |
157 | } |
158 | ||
159 | /* | |
160 | * cap_set_pg - set capabilities for all processes in a given process | |
161 | * group. We call this holding task_capability_lock and tasklist_lock. | |
162 | */ | |
41487c65 | 163 | static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective, |
1da177e4 LT |
164 | kernel_cap_t *inheritable, |
165 | kernel_cap_t *permitted) | |
166 | { | |
36c8b586 | 167 | struct task_struct *g, *target; |
1da177e4 LT |
168 | int ret = -EPERM; |
169 | int found = 0; | |
41487c65 | 170 | struct pid *pgrp; |
1da177e4 | 171 | |
8990571e | 172 | pgrp = find_vpid(pgrp_nr); |
41487c65 | 173 | do_each_pid_task(pgrp, PIDTYPE_PGID, g) { |
1da177e4 LT |
174 | target = g; |
175 | while_each_thread(g, target) { | |
176 | if (!security_capset_check(target, effective, | |
177 | inheritable, | |
178 | permitted)) { | |
179 | security_capset_set(target, effective, | |
180 | inheritable, | |
181 | permitted); | |
182 | ret = 0; | |
183 | } | |
184 | found = 1; | |
185 | } | |
41487c65 | 186 | } while_each_pid_task(pgrp, PIDTYPE_PGID, g); |
1da177e4 LT |
187 | |
188 | if (!found) | |
314f70fd | 189 | ret = 0; |
1da177e4 LT |
190 | return ret; |
191 | } | |
192 | ||
193 | /* | |
194 | * cap_set_all - set capabilities for all processes other than init | |
195 | * and self. We call this holding task_capability_lock and tasklist_lock. | |
196 | */ | |
197 | static inline int cap_set_all(kernel_cap_t *effective, | |
198 | kernel_cap_t *inheritable, | |
199 | kernel_cap_t *permitted) | |
200 | { | |
36c8b586 | 201 | struct task_struct *g, *target; |
1da177e4 LT |
202 | int ret = -EPERM; |
203 | int found = 0; | |
204 | ||
205 | do_each_thread(g, target) { | |
b460cbc5 | 206 | if (target == current || is_container_init(target->group_leader)) |
1da177e4 LT |
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 | if (!found) | |
217 | ret = 0; | |
218 | return ret; | |
219 | } | |
220 | ||
207a7ba8 RD |
221 | /** |
222 | * sys_capset - set capabilities for a process or a group of processes | |
223 | * @header: pointer to struct that contains capability version and | |
224 | * target pid data | |
225 | * @data: pointer to struct that contains the effective, permitted, | |
226 | * and inheritable capabilities | |
227 | * | |
228 | * Set capabilities for a given process, all processes, or all | |
1da177e4 LT |
229 | * processes in a given process group. |
230 | * | |
231 | * The restrictions on setting capabilities are specified as: | |
232 | * | |
233 | * [pid is for the 'target' task. 'current' is the calling task.] | |
234 | * | |
235 | * I: any raised capabilities must be a subset of the (old current) permitted | |
236 | * P: any raised capabilities must be a subset of the (old current) permitted | |
237 | * E: must be set to a subset of (new target) permitted | |
207a7ba8 RD |
238 | * |
239 | * Returns 0 on success and < 0 on error. | |
1da177e4 LT |
240 | */ |
241 | asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data) | |
242 | { | |
e338d263 AM |
243 | struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S]; |
244 | unsigned i, tocopy; | |
314f70fd DW |
245 | kernel_cap_t inheritable, permitted, effective; |
246 | __u32 version; | |
247 | struct task_struct *target; | |
248 | int ret; | |
249 | pid_t pid; | |
250 | ||
251 | if (get_user(version, &header->version)) | |
252 | return -EFAULT; | |
253 | ||
e338d263 AM |
254 | switch (version) { |
255 | case _LINUX_CAPABILITY_VERSION_1: | |
256 | warn_legacy_capability_use(); | |
257 | tocopy = _LINUX_CAPABILITY_U32S_1; | |
258 | break; | |
259 | case _LINUX_CAPABILITY_VERSION_2: | |
260 | tocopy = _LINUX_CAPABILITY_U32S_2; | |
261 | break; | |
262 | default: | |
314f70fd DW |
263 | if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) |
264 | return -EFAULT; | |
265 | return -EINVAL; | |
266 | } | |
267 | ||
268 | if (get_user(pid, &header->pid)) | |
269 | return -EFAULT; | |
270 | ||
b488893a | 271 | if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP)) |
314f70fd DW |
272 | return -EPERM; |
273 | ||
e338d263 AM |
274 | if (copy_from_user(&kdata, data, tocopy |
275 | * sizeof(struct __user_cap_data_struct))) { | |
314f70fd | 276 | return -EFAULT; |
e338d263 AM |
277 | } |
278 | ||
279 | for (i = 0; i < tocopy; i++) { | |
280 | effective.cap[i] = kdata[i].effective; | |
281 | permitted.cap[i] = kdata[i].permitted; | |
282 | inheritable.cap[i] = kdata[i].inheritable; | |
283 | } | |
284 | while (i < _LINUX_CAPABILITY_U32S) { | |
285 | effective.cap[i] = 0; | |
286 | permitted.cap[i] = 0; | |
287 | inheritable.cap[i] = 0; | |
288 | i++; | |
289 | } | |
314f70fd DW |
290 | |
291 | spin_lock(&task_capability_lock); | |
292 | read_lock(&tasklist_lock); | |
293 | ||
b488893a | 294 | if (pid > 0 && pid != task_pid_vnr(current)) { |
228ebcbe | 295 | target = find_task_by_vpid(pid); |
314f70fd DW |
296 | if (!target) { |
297 | ret = -ESRCH; | |
298 | goto out; | |
299 | } | |
300 | } else | |
301 | target = current; | |
302 | ||
303 | ret = 0; | |
304 | ||
305 | /* having verified that the proposed changes are legal, | |
306 | we now put them into effect. */ | |
307 | if (pid < 0) { | |
308 | if (pid == -1) /* all procs other than current and init */ | |
309 | ret = cap_set_all(&effective, &inheritable, &permitted); | |
310 | ||
311 | else /* all procs in process group */ | |
312 | ret = cap_set_pg(-pid, &effective, &inheritable, | |
313 | &permitted); | |
314 | } else { | |
315 | ret = security_capset_check(target, &effective, &inheritable, | |
316 | &permitted); | |
317 | if (!ret) | |
318 | security_capset_set(target, &effective, &inheritable, | |
319 | &permitted); | |
320 | } | |
1da177e4 LT |
321 | |
322 | out: | |
314f70fd DW |
323 | read_unlock(&tasklist_lock); |
324 | spin_unlock(&task_capability_lock); | |
1da177e4 | 325 | |
314f70fd | 326 | return ret; |
1da177e4 | 327 | } |
12b5989b CW |
328 | |
329 | int __capable(struct task_struct *t, int cap) | |
330 | { | |
331 | if (security_capable(t, cap) == 0) { | |
332 | t->flags |= PF_SUPERPRIV; | |
333 | return 1; | |
334 | } | |
335 | return 0; | |
336 | } | |
12b5989b CW |
337 | |
338 | int capable(int cap) | |
339 | { | |
340 | return __capable(current, cap); | |
341 | } | |
342 | EXPORT_SYMBOL(capable); |