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1/*
2 * linux/kernel/capability.c
3 *
4 * Copyright (C) 1997 Andrew Main <zefram@fysh.org>
5 *
6 * Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org>
7 * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/audit.h>
13#include <linux/capability.h>
14#include <linux/mm.h>
15#include <linux/export.h>
16#include <linux/security.h>
17#include <linux/syscalls.h>
18#include <linux/pid_namespace.h>
19#include <linux/user_namespace.h>
20#include <asm/uaccess.h>
21
22/*
23 * Leveraged for setting/resetting capabilities
24 */
25
26const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
27EXPORT_SYMBOL(__cap_empty_set);
28
29int file_caps_enabled = 1;
30
31static int __init file_caps_disable(char *str)
32{
33 file_caps_enabled = 0;
34 return 1;
35}
36__setup("no_file_caps", file_caps_disable);
37
38#ifdef CONFIG_MULTIUSER
39/*
40 * More recent versions of libcap are available from:
41 *
42 * http://www.kernel.org/pub/linux/libs/security/linux-privs/
43 */
44
45static void warn_legacy_capability_use(void)
46{
47 char name[sizeof(current->comm)];
48
49 pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n",
50 get_task_comm(name, current));
51}
52
53/*
54 * Version 2 capabilities worked fine, but the linux/capability.h file
55 * that accompanied their introduction encouraged their use without
56 * the necessary user-space source code changes. As such, we have
57 * created a version 3 with equivalent functionality to version 2, but
58 * with a header change to protect legacy source code from using
59 * version 2 when it wanted to use version 1. If your system has code
60 * that trips the following warning, it is using version 2 specific
61 * capabilities and may be doing so insecurely.
62 *
63 * The remedy is to either upgrade your version of libcap (to 2.10+,
64 * if the application is linked against it), or recompile your
65 * application with modern kernel headers and this warning will go
66 * away.
67 */
68
69static void warn_deprecated_v2(void)
70{
71 char name[sizeof(current->comm)];
72
73 pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n",
74 get_task_comm(name, current));
75}
76
77/*
78 * Version check. Return the number of u32s in each capability flag
79 * array, or a negative value on error.
80 */
81static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
82{
83 __u32 version;
84
85 if (get_user(version, &header->version))
86 return -EFAULT;
87
88 switch (version) {
89 case _LINUX_CAPABILITY_VERSION_1:
90 warn_legacy_capability_use();
91 *tocopy = _LINUX_CAPABILITY_U32S_1;
92 break;
93 case _LINUX_CAPABILITY_VERSION_2:
94 warn_deprecated_v2();
95 /*
96 * fall through - v3 is otherwise equivalent to v2.
97 */
98 case _LINUX_CAPABILITY_VERSION_3:
99 *tocopy = _LINUX_CAPABILITY_U32S_3;
100 break;
101 default:
102 if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
103 return -EFAULT;
104 return -EINVAL;
105 }
106
107 return 0;
108}
109
110/*
111 * The only thing that can change the capabilities of the current
112 * process is the current process. As such, we can't be in this code
113 * at the same time as we are in the process of setting capabilities
114 * in this process. The net result is that we can limit our use of
115 * locks to when we are reading the caps of another process.
116 */
117static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
118 kernel_cap_t *pIp, kernel_cap_t *pPp)
119{
120 int ret;
121
122 if (pid && (pid != task_pid_vnr(current))) {
123 struct task_struct *target;
124
125 rcu_read_lock();
126
127 target = find_task_by_vpid(pid);
128 if (!target)
129 ret = -ESRCH;
130 else
131 ret = security_capget(target, pEp, pIp, pPp);
132
133 rcu_read_unlock();
134 } else
135 ret = security_capget(current, pEp, pIp, pPp);
136
137 return ret;
138}
139
140/**
141 * sys_capget - get the capabilities of a given process.
142 * @header: pointer to struct that contains capability version and
143 * target pid data
144 * @dataptr: pointer to struct that contains the effective, permitted,
145 * and inheritable capabilities that are returned
146 *
147 * Returns 0 on success and < 0 on error.
148 */
149SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
150{
151 int ret = 0;
152 pid_t pid;
153 unsigned tocopy;
154 kernel_cap_t pE, pI, pP;
155
156 ret = cap_validate_magic(header, &tocopy);
157 if ((dataptr == NULL) || (ret != 0))
158 return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;
159
160 if (get_user(pid, &header->pid))
161 return -EFAULT;
162
163 if (pid < 0)
164 return -EINVAL;
165
166 ret = cap_get_target_pid(pid, &pE, &pI, &pP);
167 if (!ret) {
168 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
169 unsigned i;
170
171 for (i = 0; i < tocopy; i++) {
172 kdata[i].effective = pE.cap[i];
173 kdata[i].permitted = pP.cap[i];
174 kdata[i].inheritable = pI.cap[i];
175 }
176
177 /*
178 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
179 * we silently drop the upper capabilities here. This
180 * has the effect of making older libcap
181 * implementations implicitly drop upper capability
182 * bits when they perform a: capget/modify/capset
183 * sequence.
184 *
185 * This behavior is considered fail-safe
186 * behavior. Upgrading the application to a newer
187 * version of libcap will enable access to the newer
188 * capabilities.
189 *
190 * An alternative would be to return an error here
191 * (-ERANGE), but that causes legacy applications to
192 * unexpectedly fail; the capget/modify/capset aborts
193 * before modification is attempted and the application
194 * fails.
195 */
196 if (copy_to_user(dataptr, kdata, tocopy
197 * sizeof(struct __user_cap_data_struct))) {
198 return -EFAULT;
199 }
200 }
201
202 return ret;
203}
204
205/**
206 * sys_capset - set capabilities for a process or (*) a group of processes
207 * @header: pointer to struct that contains capability version and
208 * target pid data
209 * @data: pointer to struct that contains the effective, permitted,
210 * and inheritable capabilities
211 *
212 * Set capabilities for the current process only. The ability to any other
213 * process(es) has been deprecated and removed.
214 *
215 * The restrictions on setting capabilities are specified as:
216 *
217 * I: any raised capabilities must be a subset of the old permitted
218 * P: any raised capabilities must be a subset of the old permitted
219 * E: must be set to a subset of new permitted
220 *
221 * Returns 0 on success and < 0 on error.
222 */
223SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
224{
225 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
226 unsigned i, tocopy, copybytes;
227 kernel_cap_t inheritable, permitted, effective;
228 struct cred *new;
229 int ret;
230 pid_t pid;
231
232 ret = cap_validate_magic(header, &tocopy);
233 if (ret != 0)
234 return ret;
235
236 if (get_user(pid, &header->pid))
237 return -EFAULT;
238
239 /* may only affect current now */
240 if (pid != 0 && pid != task_pid_vnr(current))
241 return -EPERM;
242
243 copybytes = tocopy * sizeof(struct __user_cap_data_struct);
244 if (copybytes > sizeof(kdata))
245 return -EFAULT;
246
247 if (copy_from_user(&kdata, data, copybytes))
248 return -EFAULT;
249
250 for (i = 0; i < tocopy; i++) {
251 effective.cap[i] = kdata[i].effective;
252 permitted.cap[i] = kdata[i].permitted;
253 inheritable.cap[i] = kdata[i].inheritable;
254 }
255 while (i < _KERNEL_CAPABILITY_U32S) {
256 effective.cap[i] = 0;
257 permitted.cap[i] = 0;
258 inheritable.cap[i] = 0;
259 i++;
260 }
261
262 effective.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
263 permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
264 inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
265
266 new = prepare_creds();
267 if (!new)
268 return -ENOMEM;
269
270 ret = security_capset(new, current_cred(),
271 &effective, &inheritable, &permitted);
272 if (ret < 0)
273 goto error;
274
275 audit_log_capset(new, current_cred());
276
277 return commit_creds(new);
278
279error:
280 abort_creds(new);
281 return ret;
282}
283
284/**
285 * has_ns_capability - Does a task have a capability in a specific user ns
286 * @t: The task in question
287 * @ns: target user namespace
288 * @cap: The capability to be tested for
289 *
290 * Return true if the specified task has the given superior capability
291 * currently in effect to the specified user namespace, false if not.
292 *
293 * Note that this does not set PF_SUPERPRIV on the task.
294 */
295bool has_ns_capability(struct task_struct *t,
296 struct user_namespace *ns, int cap)
297{
298 int ret;
299
300 rcu_read_lock();
301 ret = security_capable(__task_cred(t), ns, cap);
302 rcu_read_unlock();
303
304 return (ret == 0);
305}
306
307/**
308 * has_capability - Does a task have a capability in init_user_ns
309 * @t: The task in question
310 * @cap: The capability to be tested for
311 *
312 * Return true if the specified task has the given superior capability
313 * currently in effect to the initial user namespace, false if not.
314 *
315 * Note that this does not set PF_SUPERPRIV on the task.
316 */
317bool has_capability(struct task_struct *t, int cap)
318{
319 return has_ns_capability(t, &init_user_ns, cap);
320}
321
322/**
323 * has_ns_capability_noaudit - Does a task have a capability (unaudited)
324 * in a specific user ns.
325 * @t: The task in question
326 * @ns: target user namespace
327 * @cap: The capability to be tested for
328 *
329 * Return true if the specified task has the given superior capability
330 * currently in effect to the specified user namespace, false if not.
331 * Do not write an audit message for the check.
332 *
333 * Note that this does not set PF_SUPERPRIV on the task.
334 */
335bool has_ns_capability_noaudit(struct task_struct *t,
336 struct user_namespace *ns, int cap)
337{
338 int ret;
339
340 rcu_read_lock();
341 ret = security_capable_noaudit(__task_cred(t), ns, cap);
342 rcu_read_unlock();
343
344 return (ret == 0);
345}
346
347/**
348 * has_capability_noaudit - Does a task have a capability (unaudited) in the
349 * initial user ns
350 * @t: The task in question
351 * @cap: The capability to be tested for
352 *
353 * Return true if the specified task has the given superior capability
354 * currently in effect to init_user_ns, false if not. Don't write an
355 * audit message for the check.
356 *
357 * Note that this does not set PF_SUPERPRIV on the task.
358 */
359bool has_capability_noaudit(struct task_struct *t, int cap)
360{
361 return has_ns_capability_noaudit(t, &init_user_ns, cap);
362}
363
364/**
365 * ns_capable - Determine if the current task has a superior capability in effect
366 * @ns: The usernamespace we want the capability in
367 * @cap: The capability to be tested for
368 *
369 * Return true if the current task has the given superior capability currently
370 * available for use, false if not.
371 *
372 * This sets PF_SUPERPRIV on the task if the capability is available on the
373 * assumption that it's about to be used.
374 */
375bool ns_capable(struct user_namespace *ns, int cap)
376{
377 if (unlikely(!cap_valid(cap))) {
378 pr_crit("capable() called with invalid cap=%u\n", cap);
379 BUG();
380 }
381
382 if (security_capable(current_cred(), ns, cap) == 0) {
383 current->flags |= PF_SUPERPRIV;
384 return true;
385 }
386 return false;
387}
388EXPORT_SYMBOL(ns_capable);
389
390
391/**
392 * capable - Determine if the current task has a superior capability in effect
393 * @cap: The capability to be tested for
394 *
395 * Return true if the current task has the given superior capability currently
396 * available for use, false if not.
397 *
398 * This sets PF_SUPERPRIV on the task if the capability is available on the
399 * assumption that it's about to be used.
400 */
401bool capable(int cap)
402{
403 return ns_capable(&init_user_ns, cap);
404}
405EXPORT_SYMBOL(capable);
406#endif /* CONFIG_MULTIUSER */
407
408/**
409 * file_ns_capable - Determine if the file's opener had a capability in effect
410 * @file: The file we want to check
411 * @ns: The usernamespace we want the capability in
412 * @cap: The capability to be tested for
413 *
414 * Return true if task that opened the file had a capability in effect
415 * when the file was opened.
416 *
417 * This does not set PF_SUPERPRIV because the caller may not
418 * actually be privileged.
419 */
420bool file_ns_capable(const struct file *file, struct user_namespace *ns,
421 int cap)
422{
423 if (WARN_ON_ONCE(!cap_valid(cap)))
424 return false;
425
426 if (security_capable(file->f_cred, ns, cap) == 0)
427 return true;
428
429 return false;
430}
431EXPORT_SYMBOL(file_ns_capable);
432
433/**
434 * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
435 * @inode: The inode in question
436 * @cap: The capability in question
437 *
438 * Return true if the current task has the given capability targeted at
439 * its own user namespace and that the given inode's uid and gid are
440 * mapped into the current user namespace.
441 */
442bool capable_wrt_inode_uidgid(const struct inode *inode, int cap)
443{
444 struct user_namespace *ns = current_user_ns();
445
446 return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid) &&
447 kgid_has_mapping(ns, inode->i_gid);
448}
449EXPORT_SYMBOL(capable_wrt_inode_uidgid);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/kernel/capability.c
4 *
5 * Copyright (C) 1997 Andrew Main <zefram@fysh.org>
6 *
7 * Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org>
8 * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/audit.h>
14#include <linux/capability.h>
15#include <linux/mm.h>
16#include <linux/export.h>
17#include <linux/security.h>
18#include <linux/syscalls.h>
19#include <linux/pid_namespace.h>
20#include <linux/user_namespace.h>
21#include <linux/uaccess.h>
22
23/*
24 * Leveraged for setting/resetting capabilities
25 */
26
27const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
28EXPORT_SYMBOL(__cap_empty_set);
29
30int file_caps_enabled = 1;
31
32static int __init file_caps_disable(char *str)
33{
34 file_caps_enabled = 0;
35 return 1;
36}
37__setup("no_file_caps", file_caps_disable);
38
39#ifdef CONFIG_MULTIUSER
40/*
41 * More recent versions of libcap are available from:
42 *
43 * http://www.kernel.org/pub/linux/libs/security/linux-privs/
44 */
45
46static void warn_legacy_capability_use(void)
47{
48 char name[sizeof(current->comm)];
49
50 pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n",
51 get_task_comm(name, current));
52}
53
54/*
55 * Version 2 capabilities worked fine, but the linux/capability.h file
56 * that accompanied their introduction encouraged their use without
57 * the necessary user-space source code changes. As such, we have
58 * created a version 3 with equivalent functionality to version 2, but
59 * with a header change to protect legacy source code from using
60 * version 2 when it wanted to use version 1. If your system has code
61 * that trips the following warning, it is using version 2 specific
62 * capabilities and may be doing so insecurely.
63 *
64 * The remedy is to either upgrade your version of libcap (to 2.10+,
65 * if the application is linked against it), or recompile your
66 * application with modern kernel headers and this warning will go
67 * away.
68 */
69
70static void warn_deprecated_v2(void)
71{
72 char name[sizeof(current->comm)];
73
74 pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n",
75 get_task_comm(name, current));
76}
77
78/*
79 * Version check. Return the number of u32s in each capability flag
80 * array, or a negative value on error.
81 */
82static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
83{
84 __u32 version;
85
86 if (get_user(version, &header->version))
87 return -EFAULT;
88
89 switch (version) {
90 case _LINUX_CAPABILITY_VERSION_1:
91 warn_legacy_capability_use();
92 *tocopy = _LINUX_CAPABILITY_U32S_1;
93 break;
94 case _LINUX_CAPABILITY_VERSION_2:
95 warn_deprecated_v2();
96 /*
97 * fall through - v3 is otherwise equivalent to v2.
98 */
99 case _LINUX_CAPABILITY_VERSION_3:
100 *tocopy = _LINUX_CAPABILITY_U32S_3;
101 break;
102 default:
103 if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
104 return -EFAULT;
105 return -EINVAL;
106 }
107
108 return 0;
109}
110
111/*
112 * The only thing that can change the capabilities of the current
113 * process is the current process. As such, we can't be in this code
114 * at the same time as we are in the process of setting capabilities
115 * in this process. The net result is that we can limit our use of
116 * locks to when we are reading the caps of another process.
117 */
118static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
119 kernel_cap_t *pIp, kernel_cap_t *pPp)
120{
121 int ret;
122
123 if (pid && (pid != task_pid_vnr(current))) {
124 struct task_struct *target;
125
126 rcu_read_lock();
127
128 target = find_task_by_vpid(pid);
129 if (!target)
130 ret = -ESRCH;
131 else
132 ret = security_capget(target, pEp, pIp, pPp);
133
134 rcu_read_unlock();
135 } else
136 ret = security_capget(current, pEp, pIp, pPp);
137
138 return ret;
139}
140
141/**
142 * sys_capget - get the capabilities of a given process.
143 * @header: pointer to struct that contains capability version and
144 * target pid data
145 * @dataptr: pointer to struct that contains the effective, permitted,
146 * and inheritable capabilities that are returned
147 *
148 * Returns 0 on success and < 0 on error.
149 */
150SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
151{
152 int ret = 0;
153 pid_t pid;
154 unsigned tocopy;
155 kernel_cap_t pE, pI, pP;
156
157 ret = cap_validate_magic(header, &tocopy);
158 if ((dataptr == NULL) || (ret != 0))
159 return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;
160
161 if (get_user(pid, &header->pid))
162 return -EFAULT;
163
164 if (pid < 0)
165 return -EINVAL;
166
167 ret = cap_get_target_pid(pid, &pE, &pI, &pP);
168 if (!ret) {
169 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
170 unsigned i;
171
172 for (i = 0; i < tocopy; i++) {
173 kdata[i].effective = pE.cap[i];
174 kdata[i].permitted = pP.cap[i];
175 kdata[i].inheritable = pI.cap[i];
176 }
177
178 /*
179 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
180 * we silently drop the upper capabilities here. This
181 * has the effect of making older libcap
182 * implementations implicitly drop upper capability
183 * bits when they perform a: capget/modify/capset
184 * sequence.
185 *
186 * This behavior is considered fail-safe
187 * behavior. Upgrading the application to a newer
188 * version of libcap will enable access to the newer
189 * capabilities.
190 *
191 * An alternative would be to return an error here
192 * (-ERANGE), but that causes legacy applications to
193 * unexpectedly fail; the capget/modify/capset aborts
194 * before modification is attempted and the application
195 * fails.
196 */
197 if (copy_to_user(dataptr, kdata, tocopy
198 * sizeof(struct __user_cap_data_struct))) {
199 return -EFAULT;
200 }
201 }
202
203 return ret;
204}
205
206/**
207 * sys_capset - set capabilities for a process or (*) a group of processes
208 * @header: pointer to struct that contains capability version and
209 * target pid data
210 * @data: pointer to struct that contains the effective, permitted,
211 * and inheritable capabilities
212 *
213 * Set capabilities for the current process only. The ability to any other
214 * process(es) has been deprecated and removed.
215 *
216 * The restrictions on setting capabilities are specified as:
217 *
218 * I: any raised capabilities must be a subset of the old permitted
219 * P: any raised capabilities must be a subset of the old permitted
220 * E: must be set to a subset of new permitted
221 *
222 * Returns 0 on success and < 0 on error.
223 */
224SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
225{
226 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
227 unsigned i, tocopy, copybytes;
228 kernel_cap_t inheritable, permitted, effective;
229 struct cred *new;
230 int ret;
231 pid_t pid;
232
233 ret = cap_validate_magic(header, &tocopy);
234 if (ret != 0)
235 return ret;
236
237 if (get_user(pid, &header->pid))
238 return -EFAULT;
239
240 /* may only affect current now */
241 if (pid != 0 && pid != task_pid_vnr(current))
242 return -EPERM;
243
244 copybytes = tocopy * sizeof(struct __user_cap_data_struct);
245 if (copybytes > sizeof(kdata))
246 return -EFAULT;
247
248 if (copy_from_user(&kdata, data, copybytes))
249 return -EFAULT;
250
251 for (i = 0; i < tocopy; i++) {
252 effective.cap[i] = kdata[i].effective;
253 permitted.cap[i] = kdata[i].permitted;
254 inheritable.cap[i] = kdata[i].inheritable;
255 }
256 while (i < _KERNEL_CAPABILITY_U32S) {
257 effective.cap[i] = 0;
258 permitted.cap[i] = 0;
259 inheritable.cap[i] = 0;
260 i++;
261 }
262
263 effective.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
264 permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
265 inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
266
267 new = prepare_creds();
268 if (!new)
269 return -ENOMEM;
270
271 ret = security_capset(new, current_cred(),
272 &effective, &inheritable, &permitted);
273 if (ret < 0)
274 goto error;
275
276 audit_log_capset(new, current_cred());
277
278 return commit_creds(new);
279
280error:
281 abort_creds(new);
282 return ret;
283}
284
285/**
286 * has_ns_capability - Does a task have a capability in a specific user ns
287 * @t: The task in question
288 * @ns: target user namespace
289 * @cap: The capability to be tested for
290 *
291 * Return true if the specified task has the given superior capability
292 * currently in effect to the specified user namespace, false if not.
293 *
294 * Note that this does not set PF_SUPERPRIV on the task.
295 */
296bool has_ns_capability(struct task_struct *t,
297 struct user_namespace *ns, int cap)
298{
299 int ret;
300
301 rcu_read_lock();
302 ret = security_capable(__task_cred(t), ns, cap);
303 rcu_read_unlock();
304
305 return (ret == 0);
306}
307
308/**
309 * has_capability - Does a task have a capability in init_user_ns
310 * @t: The task in question
311 * @cap: The capability to be tested for
312 *
313 * Return true if the specified task has the given superior capability
314 * currently in effect to the initial user namespace, false if not.
315 *
316 * Note that this does not set PF_SUPERPRIV on the task.
317 */
318bool has_capability(struct task_struct *t, int cap)
319{
320 return has_ns_capability(t, &init_user_ns, cap);
321}
322EXPORT_SYMBOL(has_capability);
323
324/**
325 * has_ns_capability_noaudit - Does a task have a capability (unaudited)
326 * in a specific user ns.
327 * @t: The task in question
328 * @ns: target user namespace
329 * @cap: The capability to be tested for
330 *
331 * Return true if the specified task has the given superior capability
332 * currently in effect to the specified user namespace, false if not.
333 * Do not write an audit message for the check.
334 *
335 * Note that this does not set PF_SUPERPRIV on the task.
336 */
337bool has_ns_capability_noaudit(struct task_struct *t,
338 struct user_namespace *ns, int cap)
339{
340 int ret;
341
342 rcu_read_lock();
343 ret = security_capable_noaudit(__task_cred(t), ns, cap);
344 rcu_read_unlock();
345
346 return (ret == 0);
347}
348
349/**
350 * has_capability_noaudit - Does a task have a capability (unaudited) in the
351 * initial user ns
352 * @t: The task in question
353 * @cap: The capability to be tested for
354 *
355 * Return true if the specified task has the given superior capability
356 * currently in effect to init_user_ns, false if not. Don't write an
357 * audit message for the check.
358 *
359 * Note that this does not set PF_SUPERPRIV on the task.
360 */
361bool has_capability_noaudit(struct task_struct *t, int cap)
362{
363 return has_ns_capability_noaudit(t, &init_user_ns, cap);
364}
365
366static bool ns_capable_common(struct user_namespace *ns, int cap, bool audit)
367{
368 int capable;
369
370 if (unlikely(!cap_valid(cap))) {
371 pr_crit("capable() called with invalid cap=%u\n", cap);
372 BUG();
373 }
374
375 capable = audit ? security_capable(current_cred(), ns, cap) :
376 security_capable_noaudit(current_cred(), ns, cap);
377 if (capable == 0) {
378 current->flags |= PF_SUPERPRIV;
379 return true;
380 }
381 return false;
382}
383
384/**
385 * ns_capable - Determine if the current task has a superior capability in effect
386 * @ns: The usernamespace we want the capability in
387 * @cap: The capability to be tested for
388 *
389 * Return true if the current task has the given superior capability currently
390 * available for use, false if not.
391 *
392 * This sets PF_SUPERPRIV on the task if the capability is available on the
393 * assumption that it's about to be used.
394 */
395bool ns_capable(struct user_namespace *ns, int cap)
396{
397 return ns_capable_common(ns, cap, true);
398}
399EXPORT_SYMBOL(ns_capable);
400
401/**
402 * ns_capable_noaudit - Determine if the current task has a superior capability
403 * (unaudited) in effect
404 * @ns: The usernamespace we want the capability in
405 * @cap: The capability to be tested for
406 *
407 * Return true if the current task has the given superior capability currently
408 * available for use, false if not.
409 *
410 * This sets PF_SUPERPRIV on the task if the capability is available on the
411 * assumption that it's about to be used.
412 */
413bool ns_capable_noaudit(struct user_namespace *ns, int cap)
414{
415 return ns_capable_common(ns, cap, false);
416}
417EXPORT_SYMBOL(ns_capable_noaudit);
418
419/**
420 * capable - Determine if the current task has a superior capability in effect
421 * @cap: The capability to be tested for
422 *
423 * Return true if the current task has the given superior capability currently
424 * available for use, false if not.
425 *
426 * This sets PF_SUPERPRIV on the task if the capability is available on the
427 * assumption that it's about to be used.
428 */
429bool capable(int cap)
430{
431 return ns_capable(&init_user_ns, cap);
432}
433EXPORT_SYMBOL(capable);
434#endif /* CONFIG_MULTIUSER */
435
436/**
437 * file_ns_capable - Determine if the file's opener had a capability in effect
438 * @file: The file we want to check
439 * @ns: The usernamespace we want the capability in
440 * @cap: The capability to be tested for
441 *
442 * Return true if task that opened the file had a capability in effect
443 * when the file was opened.
444 *
445 * This does not set PF_SUPERPRIV because the caller may not
446 * actually be privileged.
447 */
448bool file_ns_capable(const struct file *file, struct user_namespace *ns,
449 int cap)
450{
451 if (WARN_ON_ONCE(!cap_valid(cap)))
452 return false;
453
454 if (security_capable(file->f_cred, ns, cap) == 0)
455 return true;
456
457 return false;
458}
459EXPORT_SYMBOL(file_ns_capable);
460
461/**
462 * privileged_wrt_inode_uidgid - Do capabilities in the namespace work over the inode?
463 * @ns: The user namespace in question
464 * @inode: The inode in question
465 *
466 * Return true if the inode uid and gid are within the namespace.
467 */
468bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct inode *inode)
469{
470 return kuid_has_mapping(ns, inode->i_uid) &&
471 kgid_has_mapping(ns, inode->i_gid);
472}
473
474/**
475 * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
476 * @inode: The inode in question
477 * @cap: The capability in question
478 *
479 * Return true if the current task has the given capability targeted at
480 * its own user namespace and that the given inode's uid and gid are
481 * mapped into the current user namespace.
482 */
483bool capable_wrt_inode_uidgid(const struct inode *inode, int cap)
484{
485 struct user_namespace *ns = current_user_ns();
486
487 return ns_capable(ns, cap) && privileged_wrt_inode_uidgid(ns, inode);
488}
489EXPORT_SYMBOL(capable_wrt_inode_uidgid);
490
491/**
492 * ptracer_capable - Determine if the ptracer holds CAP_SYS_PTRACE in the namespace
493 * @tsk: The task that may be ptraced
494 * @ns: The user namespace to search for CAP_SYS_PTRACE in
495 *
496 * Return true if the task that is ptracing the current task had CAP_SYS_PTRACE
497 * in the specified user namespace.
498 */
499bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns)
500{
501 int ret = 0; /* An absent tracer adds no restrictions */
502 const struct cred *cred;
503 rcu_read_lock();
504 cred = rcu_dereference(tsk->ptracer_cred);
505 if (cred)
506 ret = security_capable_noaudit(cred, ns, CAP_SYS_PTRACE);
507 rcu_read_unlock();
508 return (ret == 0);
509}