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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 fallthrough; /* v3 is otherwise equivalent to v2 */
97 case _LINUX_CAPABILITY_VERSION_3:
98 *tocopy = _LINUX_CAPABILITY_U32S_3;
99 break;
100 default:
101 if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
102 return -EFAULT;
103 return -EINVAL;
104 }
105
106 return 0;
107}
108
109/*
110 * The only thing that can change the capabilities of the current
111 * process is the current process. As such, we can't be in this code
112 * at the same time as we are in the process of setting capabilities
113 * in this process. The net result is that we can limit our use of
114 * locks to when we are reading the caps of another process.
115 */
116static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
117 kernel_cap_t *pIp, kernel_cap_t *pPp)
118{
119 int ret;
120
121 if (pid && (pid != task_pid_vnr(current))) {
122 struct task_struct *target;
123
124 rcu_read_lock();
125
126 target = find_task_by_vpid(pid);
127 if (!target)
128 ret = -ESRCH;
129 else
130 ret = security_capget(target, pEp, pIp, pPp);
131
132 rcu_read_unlock();
133 } else
134 ret = security_capget(current, pEp, pIp, pPp);
135
136 return ret;
137}
138
139/**
140 * sys_capget - get the capabilities of a given process.
141 * @header: pointer to struct that contains capability version and
142 * target pid data
143 * @dataptr: pointer to struct that contains the effective, permitted,
144 * and inheritable capabilities that are returned
145 *
146 * Returns 0 on success and < 0 on error.
147 */
148SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
149{
150 int ret = 0;
151 pid_t pid;
152 unsigned tocopy;
153 kernel_cap_t pE, pI, pP;
154
155 ret = cap_validate_magic(header, &tocopy);
156 if ((dataptr == NULL) || (ret != 0))
157 return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;
158
159 if (get_user(pid, &header->pid))
160 return -EFAULT;
161
162 if (pid < 0)
163 return -EINVAL;
164
165 ret = cap_get_target_pid(pid, &pE, &pI, &pP);
166 if (!ret) {
167 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
168 unsigned i;
169
170 for (i = 0; i < tocopy; i++) {
171 kdata[i].effective = pE.cap[i];
172 kdata[i].permitted = pP.cap[i];
173 kdata[i].inheritable = pI.cap[i];
174 }
175
176 /*
177 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
178 * we silently drop the upper capabilities here. This
179 * has the effect of making older libcap
180 * implementations implicitly drop upper capability
181 * bits when they perform a: capget/modify/capset
182 * sequence.
183 *
184 * This behavior is considered fail-safe
185 * behavior. Upgrading the application to a newer
186 * version of libcap will enable access to the newer
187 * capabilities.
188 *
189 * An alternative would be to return an error here
190 * (-ERANGE), but that causes legacy applications to
191 * unexpectedly fail; the capget/modify/capset aborts
192 * before modification is attempted and the application
193 * fails.
194 */
195 if (copy_to_user(dataptr, kdata, tocopy
196 * sizeof(struct __user_cap_data_struct))) {
197 return -EFAULT;
198 }
199 }
200
201 return ret;
202}
203
204/**
205 * sys_capset - set capabilities for a process or (*) a group of processes
206 * @header: pointer to struct that contains capability version and
207 * target pid data
208 * @data: pointer to struct that contains the effective, permitted,
209 * and inheritable capabilities
210 *
211 * Set capabilities for the current process only. The ability to any other
212 * process(es) has been deprecated and removed.
213 *
214 * The restrictions on setting capabilities are specified as:
215 *
216 * I: any raised capabilities must be a subset of the old permitted
217 * P: any raised capabilities must be a subset of the old permitted
218 * E: must be set to a subset of new permitted
219 *
220 * Returns 0 on success and < 0 on error.
221 */
222SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
223{
224 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
225 unsigned i, tocopy, copybytes;
226 kernel_cap_t inheritable, permitted, effective;
227 struct cred *new;
228 int ret;
229 pid_t pid;
230
231 ret = cap_validate_magic(header, &tocopy);
232 if (ret != 0)
233 return ret;
234
235 if (get_user(pid, &header->pid))
236 return -EFAULT;
237
238 /* may only affect current now */
239 if (pid != 0 && pid != task_pid_vnr(current))
240 return -EPERM;
241
242 copybytes = tocopy * sizeof(struct __user_cap_data_struct);
243 if (copybytes > sizeof(kdata))
244 return -EFAULT;
245
246 if (copy_from_user(&kdata, data, copybytes))
247 return -EFAULT;
248
249 for (i = 0; i < tocopy; i++) {
250 effective.cap[i] = kdata[i].effective;
251 permitted.cap[i] = kdata[i].permitted;
252 inheritable.cap[i] = kdata[i].inheritable;
253 }
254 while (i < _KERNEL_CAPABILITY_U32S) {
255 effective.cap[i] = 0;
256 permitted.cap[i] = 0;
257 inheritable.cap[i] = 0;
258 i++;
259 }
260
261 effective.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
262 permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
263 inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
264
265 new = prepare_creds();
266 if (!new)
267 return -ENOMEM;
268
269 ret = security_capset(new, current_cred(),
270 &effective, &inheritable, &permitted);
271 if (ret < 0)
272 goto error;
273
274 audit_log_capset(new, current_cred());
275
276 return commit_creds(new);
277
278error:
279 abort_creds(new);
280 return ret;
281}
282
283/**
284 * has_ns_capability - Does a task have a capability in a specific user ns
285 * @t: The task in question
286 * @ns: target user namespace
287 * @cap: The capability to be tested for
288 *
289 * Return true if the specified task has the given superior capability
290 * currently in effect to the specified user namespace, false if not.
291 *
292 * Note that this does not set PF_SUPERPRIV on the task.
293 */
294bool has_ns_capability(struct task_struct *t,
295 struct user_namespace *ns, int cap)
296{
297 int ret;
298
299 rcu_read_lock();
300 ret = security_capable(__task_cred(t), ns, cap, CAP_OPT_NONE);
301 rcu_read_unlock();
302
303 return (ret == 0);
304}
305
306/**
307 * has_capability - Does a task have a capability in init_user_ns
308 * @t: The task in question
309 * @cap: The capability to be tested for
310 *
311 * Return true if the specified task has the given superior capability
312 * currently in effect to the initial user namespace, false if not.
313 *
314 * Note that this does not set PF_SUPERPRIV on the task.
315 */
316bool has_capability(struct task_struct *t, int cap)
317{
318 return has_ns_capability(t, &init_user_ns, cap);
319}
320EXPORT_SYMBOL(has_capability);
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(__task_cred(t), ns, cap, CAP_OPT_NOAUDIT);
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}
363EXPORT_SYMBOL(has_capability_noaudit);
364
365static bool ns_capable_common(struct user_namespace *ns,
366 int cap,
367 unsigned int opts)
368{
369 int capable;
370
371 if (unlikely(!cap_valid(cap))) {
372 pr_crit("capable() called with invalid cap=%u\n", cap);
373 BUG();
374 }
375
376 capable = security_capable(current_cred(), ns, cap, opts);
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, CAP_OPT_NONE);
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, CAP_OPT_NOAUDIT);
416}
417EXPORT_SYMBOL(ns_capable_noaudit);
418
419/**
420 * ns_capable_setid - Determine if the current task has a superior capability
421 * in effect, while signalling that this check is being done from within a
422 * setid or setgroups syscall.
423 * @ns: The usernamespace we want the capability in
424 * @cap: The capability to be tested for
425 *
426 * Return true if the current task has the given superior capability currently
427 * available for use, false if not.
428 *
429 * This sets PF_SUPERPRIV on the task if the capability is available on the
430 * assumption that it's about to be used.
431 */
432bool ns_capable_setid(struct user_namespace *ns, int cap)
433{
434 return ns_capable_common(ns, cap, CAP_OPT_INSETID);
435}
436EXPORT_SYMBOL(ns_capable_setid);
437
438/**
439 * capable - Determine if the current task has a superior capability in effect
440 * @cap: The capability to be tested for
441 *
442 * Return true if the current task has the given superior capability currently
443 * available for use, false if not.
444 *
445 * This sets PF_SUPERPRIV on the task if the capability is available on the
446 * assumption that it's about to be used.
447 */
448bool capable(int cap)
449{
450 return ns_capable(&init_user_ns, cap);
451}
452EXPORT_SYMBOL(capable);
453#endif /* CONFIG_MULTIUSER */
454
455/**
456 * file_ns_capable - Determine if the file's opener had a capability in effect
457 * @file: The file we want to check
458 * @ns: The usernamespace we want the capability in
459 * @cap: The capability to be tested for
460 *
461 * Return true if task that opened the file had a capability in effect
462 * when the file was opened.
463 *
464 * This does not set PF_SUPERPRIV because the caller may not
465 * actually be privileged.
466 */
467bool file_ns_capable(const struct file *file, struct user_namespace *ns,
468 int cap)
469{
470
471 if (WARN_ON_ONCE(!cap_valid(cap)))
472 return false;
473
474 if (security_capable(file->f_cred, ns, cap, CAP_OPT_NONE) == 0)
475 return true;
476
477 return false;
478}
479EXPORT_SYMBOL(file_ns_capable);
480
481/**
482 * privileged_wrt_inode_uidgid - Do capabilities in the namespace work over the inode?
483 * @ns: The user namespace in question
484 * @inode: The inode in question
485 *
486 * Return true if the inode uid and gid are within the namespace.
487 */
488bool privileged_wrt_inode_uidgid(struct user_namespace *ns,
489 struct user_namespace *mnt_userns,
490 const struct inode *inode)
491{
492 return vfsuid_has_mapping(ns, i_uid_into_vfsuid(mnt_userns, inode)) &&
493 vfsgid_has_mapping(ns, i_gid_into_vfsgid(mnt_userns, inode));
494}
495
496/**
497 * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
498 * @inode: The inode in question
499 * @cap: The capability in question
500 *
501 * Return true if the current task has the given capability targeted at
502 * its own user namespace and that the given inode's uid and gid are
503 * mapped into the current user namespace.
504 */
505bool capable_wrt_inode_uidgid(struct user_namespace *mnt_userns,
506 const struct inode *inode, int cap)
507{
508 struct user_namespace *ns = current_user_ns();
509
510 return ns_capable(ns, cap) &&
511 privileged_wrt_inode_uidgid(ns, mnt_userns, inode);
512}
513EXPORT_SYMBOL(capable_wrt_inode_uidgid);
514
515/**
516 * ptracer_capable - Determine if the ptracer holds CAP_SYS_PTRACE in the namespace
517 * @tsk: The task that may be ptraced
518 * @ns: The user namespace to search for CAP_SYS_PTRACE in
519 *
520 * Return true if the task that is ptracing the current task had CAP_SYS_PTRACE
521 * in the specified user namespace.
522 */
523bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns)
524{
525 int ret = 0; /* An absent tracer adds no restrictions */
526 const struct cred *cred;
527
528 rcu_read_lock();
529 cred = rcu_dereference(tsk->ptracer_cred);
530 if (cred)
531 ret = security_capable(cred, ns, CAP_SYS_PTRACE,
532 CAP_OPT_NOAUDIT);
533 rcu_read_unlock();
534 return (ret == 0);
535}
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;
27
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/*
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 * unexpectidly 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 new = prepare_creds();
263 if (!new)
264 return -ENOMEM;
265
266 ret = security_capset(new, current_cred(),
267 &effective, &inheritable, &permitted);
268 if (ret < 0)
269 goto error;
270
271 audit_log_capset(new, current_cred());
272
273 return commit_creds(new);
274
275error:
276 abort_creds(new);
277 return ret;
278}
279
280/**
281 * has_ns_capability - Does a task have a capability in a specific user ns
282 * @t: The task in question
283 * @ns: target user namespace
284 * @cap: The capability to be tested for
285 *
286 * Return true if the specified task has the given superior capability
287 * currently in effect to the specified user namespace, false if not.
288 *
289 * Note that this does not set PF_SUPERPRIV on the task.
290 */
291bool has_ns_capability(struct task_struct *t,
292 struct user_namespace *ns, int cap)
293{
294 int ret;
295
296 rcu_read_lock();
297 ret = security_capable(__task_cred(t), ns, cap);
298 rcu_read_unlock();
299
300 return (ret == 0);
301}
302
303/**
304 * has_capability - Does a task have a capability in init_user_ns
305 * @t: The task in question
306 * @cap: The capability to be tested for
307 *
308 * Return true if the specified task has the given superior capability
309 * currently in effect to the initial user namespace, false if not.
310 *
311 * Note that this does not set PF_SUPERPRIV on the task.
312 */
313bool has_capability(struct task_struct *t, int cap)
314{
315 return has_ns_capability(t, &init_user_ns, cap);
316}
317
318/**
319 * has_ns_capability_noaudit - Does a task have a capability (unaudited)
320 * in a specific user ns.
321 * @t: The task in question
322 * @ns: target user namespace
323 * @cap: The capability to be tested for
324 *
325 * Return true if the specified task has the given superior capability
326 * currently in effect to the specified user namespace, false if not.
327 * Do not write an audit message for the check.
328 *
329 * Note that this does not set PF_SUPERPRIV on the task.
330 */
331bool has_ns_capability_noaudit(struct task_struct *t,
332 struct user_namespace *ns, int cap)
333{
334 int ret;
335
336 rcu_read_lock();
337 ret = security_capable_noaudit(__task_cred(t), ns, cap);
338 rcu_read_unlock();
339
340 return (ret == 0);
341}
342
343/**
344 * has_capability_noaudit - Does a task have a capability (unaudited) in the
345 * initial user ns
346 * @t: The task in question
347 * @cap: The capability to be tested for
348 *
349 * Return true if the specified task has the given superior capability
350 * currently in effect to init_user_ns, false if not. Don't write an
351 * audit message for the check.
352 *
353 * Note that this does not set PF_SUPERPRIV on the task.
354 */
355bool has_capability_noaudit(struct task_struct *t, int cap)
356{
357 return has_ns_capability_noaudit(t, &init_user_ns, cap);
358}
359
360/**
361 * ns_capable - Determine if the current task has a superior capability in effect
362 * @ns: The usernamespace we want the capability in
363 * @cap: The capability to be tested for
364 *
365 * Return true if the current task has the given superior capability currently
366 * available for use, false if not.
367 *
368 * This sets PF_SUPERPRIV on the task if the capability is available on the
369 * assumption that it's about to be used.
370 */
371bool ns_capable(struct user_namespace *ns, int cap)
372{
373 if (unlikely(!cap_valid(cap))) {
374 pr_crit("capable() called with invalid cap=%u\n", cap);
375 BUG();
376 }
377
378 if (security_capable(current_cred(), ns, cap) == 0) {
379 current->flags |= PF_SUPERPRIV;
380 return true;
381 }
382 return false;
383}
384EXPORT_SYMBOL(ns_capable);
385
386/**
387 * file_ns_capable - Determine if the file's opener had a capability in effect
388 * @file: The file we want to check
389 * @ns: The usernamespace we want the capability in
390 * @cap: The capability to be tested for
391 *
392 * Return true if task that opened the file had a capability in effect
393 * when the file was opened.
394 *
395 * This does not set PF_SUPERPRIV because the caller may not
396 * actually be privileged.
397 */
398bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap)
399{
400 if (WARN_ON_ONCE(!cap_valid(cap)))
401 return false;
402
403 if (security_capable(file->f_cred, ns, cap) == 0)
404 return true;
405
406 return false;
407}
408EXPORT_SYMBOL(file_ns_capable);
409
410/**
411 * capable - Determine if the current task has a superior capability in effect
412 * @cap: The capability to be tested for
413 *
414 * Return true if the current task has the given superior capability currently
415 * available for use, false if not.
416 *
417 * This sets PF_SUPERPRIV on the task if the capability is available on the
418 * assumption that it's about to be used.
419 */
420bool capable(int cap)
421{
422 return ns_capable(&init_user_ns, cap);
423}
424EXPORT_SYMBOL(capable);
425
426/**
427 * inode_capable - Check superior capability over inode
428 * @inode: The inode in question
429 * @cap: The capability in question
430 *
431 * Return true if the current task has the given superior capability
432 * targeted at it's own user namespace and that the given inode is owned
433 * by the current user namespace or a child namespace.
434 *
435 * Currently we check to see if an inode is owned by the current
436 * user namespace by seeing if the inode's owner maps into the
437 * current user namespace.
438 *
439 */
440bool inode_capable(const struct inode *inode, int cap)
441{
442 struct user_namespace *ns = current_user_ns();
443
444 return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid);
445}
446EXPORT_SYMBOL(inode_capable);