projects/linux·blob v2.6.25-rc3 · refs

342 lines · 8.3 KiB

1/*
2 * linux/kernel/capability.c
3 *
4 * Copyright (C) 1997 Andrew Main <[email protected]>
5 *
6 * Integrated into 2.1.97+, Andrew G. Morgan <[email protected]>
7 * 30 May 2002: Cleanup, Robert M. Love <[email protected]>
8 */
9
10#include <linux/capability.h>
11#include <linux/mm.h>
12#include <linux/module.h>
13#include <linux/security.h>
14#include <linux/syscalls.h>
15#include <linux/pid_namespace.h>
16#include <asm/uaccess.h>
17
18/*
19 * This lock protects task->cap_* for all tasks including current.
20 * Locking rule: acquire this prior to tasklist_lock.
21 */
22static DEFINE_SPINLOCK(task_capability_lock);
23
24/*
25 * Leveraged for setting/resetting capabilities
26 */
27
28const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
29const kernel_cap_t __cap_full_set = CAP_FULL_SET;
30const kernel_cap_t __cap_init_eff_set = CAP_INIT_EFF_SET;
31
32EXPORT_SYMBOL(__cap_empty_set);
33EXPORT_SYMBOL(__cap_full_set);
34EXPORT_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
42static 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
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
61/**
62 * sys_capget - get the capabilities of a given process.
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.
69 */
70asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
71{
72 int ret = 0;
73 pid_t pid;
74 __u32 version;
75 struct task_struct *target;
76 unsigned tocopy;
77 kernel_cap_t pE, pI, pP;
78
79 if (get_user(version, &header->version))
80 return -EFAULT;
81
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:
91 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
92 return -EFAULT;
93 return -EINVAL;
94 }
95
96 if (get_user(pid, &header->pid))
97 return -EFAULT;
98
99 if (pid < 0)
100 return -EINVAL;
101
102 spin_lock(&task_capability_lock);
103 read_lock(&tasklist_lock);
104
105 if (pid && pid != task_pid_vnr(current)) {
106 target = find_task_by_vpid(pid);
107 if (!target) {
108 ret = -ESRCH;
109 goto out;
110 }
111 } else
112 target = current;
113
114 ret = security_capget(target, &pE, &pI, &pP);
115
116out:
117 read_unlock(&tasklist_lock);
118 spin_unlock(&task_capability_lock);
119
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 }
155
156 return ret;
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 */
163static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
164 kernel_cap_t *inheritable,
165 kernel_cap_t *permitted)
166{
167 struct task_struct *g, *target;
168 int ret = -EPERM;
169 int found = 0;
170 struct pid *pgrp;
171
172 pgrp = find_vpid(pgrp_nr);
173 do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
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 }
186 } while_each_pid_task(pgrp, PIDTYPE_PGID, g);
187
188 if (!found)
189 ret = 0;
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 */
197static inline int cap_set_all(kernel_cap_t *effective,
198 kernel_cap_t *inheritable,
199 kernel_cap_t *permitted)
200{
201 struct task_struct *g, *target;
202 int ret = -EPERM;
203 int found = 0;
204
205 do_each_thread(g, target) {
206 if (target == current || 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 if (!found)
217 ret = 0;
218 return ret;
219}
220
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
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
238 *
239 * Returns 0 on success and < 0 on error.
240 */
241asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
242{
243 struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S];
244 unsigned i, tocopy;
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
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:
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
271 if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP))
272 return -EPERM;
273
274 if (copy_from_user(&kdata, data, tocopy
275 * sizeof(struct __user_cap_data_struct))) {
276 return -EFAULT;
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 }
290
291 spin_lock(&task_capability_lock);
292 read_lock(&tasklist_lock);
293
294 if (pid > 0 && pid != task_pid_vnr(current)) {
295 target = find_task_by_vpid(pid);
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 }
321
322out:
323 read_unlock(&tasklist_lock);
324 spin_unlock(&task_capability_lock);
325
326 return ret;
327}
328
329int __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}
337
338int capable(int cap)
339{
340 return __capable(current, cap);
341}
342EXPORT_SYMBOL(capable);