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v4.17
  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}
v6.9.4
  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
 
 
 
 
 
 
 
 23int file_caps_enabled = 1;
 24
 25static int __init file_caps_disable(char *str)
 26{
 27	file_caps_enabled = 0;
 28	return 1;
 29}
 30__setup("no_file_caps", file_caps_disable);
 31
 32#ifdef CONFIG_MULTIUSER
 33/*
 34 * More recent versions of libcap are available from:
 35 *
 36 *   http://www.kernel.org/pub/linux/libs/security/linux-privs/
 37 */
 38
 39static void warn_legacy_capability_use(void)
 40{
 41	char name[sizeof(current->comm)];
 42
 43	pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n",
 44		     get_task_comm(name, current));
 45}
 46
 47/*
 48 * Version 2 capabilities worked fine, but the linux/capability.h file
 49 * that accompanied their introduction encouraged their use without
 50 * the necessary user-space source code changes. As such, we have
 51 * created a version 3 with equivalent functionality to version 2, but
 52 * with a header change to protect legacy source code from using
 53 * version 2 when it wanted to use version 1. If your system has code
 54 * that trips the following warning, it is using version 2 specific
 55 * capabilities and may be doing so insecurely.
 56 *
 57 * The remedy is to either upgrade your version of libcap (to 2.10+,
 58 * if the application is linked against it), or recompile your
 59 * application with modern kernel headers and this warning will go
 60 * away.
 61 */
 62
 63static void warn_deprecated_v2(void)
 64{
 65	char name[sizeof(current->comm)];
 66
 67	pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n",
 68		     get_task_comm(name, current));
 69}
 70
 71/*
 72 * Version check. Return the number of u32s in each capability flag
 73 * array, or a negative value on error.
 74 */
 75static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
 76{
 77	__u32 version;
 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		warn_deprecated_v2();
 89		fallthrough;	/* v3 is otherwise equivalent to v2 */
 
 
 90	case _LINUX_CAPABILITY_VERSION_3:
 91		*tocopy = _LINUX_CAPABILITY_U32S_3;
 92		break;
 93	default:
 94		if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
 95			return -EFAULT;
 96		return -EINVAL;
 97	}
 98
 99	return 0;
100}
101
102/*
103 * The only thing that can change the capabilities of the current
104 * process is the current process. As such, we can't be in this code
105 * at the same time as we are in the process of setting capabilities
106 * in this process. The net result is that we can limit our use of
107 * locks to when we are reading the caps of another process.
108 */
109static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
110				     kernel_cap_t *pIp, kernel_cap_t *pPp)
111{
112	int ret;
113
114	if (pid && (pid != task_pid_vnr(current))) {
115		const struct task_struct *target;
116
117		rcu_read_lock();
118
119		target = find_task_by_vpid(pid);
120		if (!target)
121			ret = -ESRCH;
122		else
123			ret = security_capget(target, pEp, pIp, pPp);
124
125		rcu_read_unlock();
126	} else
127		ret = security_capget(current, pEp, pIp, pPp);
128
129	return ret;
130}
131
132/**
133 * sys_capget - get the capabilities of a given process.
134 * @header: pointer to struct that contains capability version and
135 *	target pid data
136 * @dataptr: pointer to struct that contains the effective, permitted,
137 *	and inheritable capabilities that are returned
138 *
139 * Returns 0 on success and < 0 on error.
140 */
141SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
142{
143	int ret = 0;
144	pid_t pid;
145	unsigned tocopy;
146	kernel_cap_t pE, pI, pP;
147	struct __user_cap_data_struct kdata[2];
148
149	ret = cap_validate_magic(header, &tocopy);
150	if ((dataptr == NULL) || (ret != 0))
151		return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;
152
153	if (get_user(pid, &header->pid))
154		return -EFAULT;
155
156	if (pid < 0)
157		return -EINVAL;
158
159	ret = cap_get_target_pid(pid, &pE, &pI, &pP);
160	if (ret)
161		return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
162
163	/*
164	 * Annoying legacy format with 64-bit capabilities exposed
165	 * as two sets of 32-bit fields, so we need to split the
166	 * capability values up.
167	 */
168	kdata[0].effective   = pE.val; kdata[1].effective   = pE.val >> 32;
169	kdata[0].permitted   = pP.val; kdata[1].permitted   = pP.val >> 32;
170	kdata[0].inheritable = pI.val; kdata[1].inheritable = pI.val >> 32;
171
172	/*
173	 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
174	 * we silently drop the upper capabilities here. This
175	 * has the effect of making older libcap
176	 * implementations implicitly drop upper capability
177	 * bits when they perform a: capget/modify/capset
178	 * sequence.
179	 *
180	 * This behavior is considered fail-safe
181	 * behavior. Upgrading the application to a newer
182	 * version of libcap will enable access to the newer
183	 * capabilities.
184	 *
185	 * An alternative would be to return an error here
186	 * (-ERANGE), but that causes legacy applications to
187	 * unexpectedly fail; the capget/modify/capset aborts
188	 * before modification is attempted and the application
189	 * fails.
190	 */
191	if (copy_to_user(dataptr, kdata, tocopy * sizeof(kdata[0])))
192		return -EFAULT;
193
194	return 0;
195}
196
197static kernel_cap_t mk_kernel_cap(u32 low, u32 high)
198{
199	return (kernel_cap_t) { (low | ((u64)high << 32)) & CAP_VALID_MASK };
200}
201
202/**
203 * sys_capset - set capabilities for a process or (*) a group of processes
204 * @header: pointer to struct that contains capability version and
205 *	target pid data
206 * @data: pointer to struct that contains the effective, permitted,
207 *	and inheritable capabilities
208 *
209 * Set capabilities for the current process only.  The ability to any other
210 * process(es) has been deprecated and removed.
211 *
212 * The restrictions on setting capabilities are specified as:
213 *
214 * I: any raised capabilities must be a subset of the old permitted
215 * P: any raised capabilities must be a subset of the old permitted
216 * E: must be set to a subset of new permitted
217 *
218 * Returns 0 on success and < 0 on error.
219 */
220SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
221{
222	struct __user_cap_data_struct kdata[2] = { { 0, }, };
223	unsigned tocopy, copybytes;
224	kernel_cap_t inheritable, permitted, effective;
225	struct cred *new;
226	int ret;
227	pid_t pid;
228
229	ret = cap_validate_magic(header, &tocopy);
230	if (ret != 0)
231		return ret;
232
233	if (get_user(pid, &header->pid))
234		return -EFAULT;
235
236	/* may only affect current now */
237	if (pid != 0 && pid != task_pid_vnr(current))
238		return -EPERM;
239
240	copybytes = tocopy * sizeof(struct __user_cap_data_struct);
241	if (copybytes > sizeof(kdata))
242		return -EFAULT;
243
244	if (copy_from_user(&kdata, data, copybytes))
245		return -EFAULT;
246
247	effective   = mk_kernel_cap(kdata[0].effective,   kdata[1].effective);
248	permitted   = mk_kernel_cap(kdata[0].permitted,   kdata[1].permitted);
249	inheritable = mk_kernel_cap(kdata[0].inheritable, kdata[1].inheritable);
 
 
 
 
 
 
 
 
 
 
 
 
250
251	new = prepare_creds();
252	if (!new)
253		return -ENOMEM;
254
255	ret = security_capset(new, current_cred(),
256			      &effective, &inheritable, &permitted);
257	if (ret < 0)
258		goto error;
259
260	audit_log_capset(new, current_cred());
261
262	return commit_creds(new);
263
264error:
265	abort_creds(new);
266	return ret;
267}
268
269/**
270 * has_ns_capability - Does a task have a capability in a specific user ns
271 * @t: The task in question
272 * @ns: target user namespace
273 * @cap: The capability to be tested for
274 *
275 * Return true if the specified task has the given superior capability
276 * currently in effect to the specified user namespace, false if not.
277 *
278 * Note that this does not set PF_SUPERPRIV on the task.
279 */
280bool has_ns_capability(struct task_struct *t,
281		       struct user_namespace *ns, int cap)
282{
283	int ret;
284
285	rcu_read_lock();
286	ret = security_capable(__task_cred(t), ns, cap, CAP_OPT_NONE);
287	rcu_read_unlock();
288
289	return (ret == 0);
290}
291
292/**
293 * has_capability - Does a task have a capability in init_user_ns
294 * @t: The task in question
295 * @cap: The capability to be tested for
296 *
297 * Return true if the specified task has the given superior capability
298 * currently in effect to the initial user namespace, false if not.
299 *
300 * Note that this does not set PF_SUPERPRIV on the task.
301 */
302bool has_capability(struct task_struct *t, int cap)
303{
304	return has_ns_capability(t, &init_user_ns, cap);
305}
306EXPORT_SYMBOL(has_capability);
307
308/**
309 * has_ns_capability_noaudit - Does a task have a capability (unaudited)
310 * in a specific user ns.
311 * @t: The task in question
312 * @ns: target user namespace
313 * @cap: The capability to be tested for
314 *
315 * Return true if the specified task has the given superior capability
316 * currently in effect to the specified user namespace, false if not.
317 * Do not write an audit message for the check.
318 *
319 * Note that this does not set PF_SUPERPRIV on the task.
320 */
321bool has_ns_capability_noaudit(struct task_struct *t,
322			       struct user_namespace *ns, int cap)
323{
324	int ret;
325
326	rcu_read_lock();
327	ret = security_capable(__task_cred(t), ns, cap, CAP_OPT_NOAUDIT);
328	rcu_read_unlock();
329
330	return (ret == 0);
331}
332
333/**
334 * has_capability_noaudit - Does a task have a capability (unaudited) in the
335 * initial user ns
336 * @t: The task in question
337 * @cap: The capability to be tested for
338 *
339 * Return true if the specified task has the given superior capability
340 * currently in effect to init_user_ns, false if not.  Don't write an
341 * audit message for the check.
342 *
343 * Note that this does not set PF_SUPERPRIV on the task.
344 */
345bool has_capability_noaudit(struct task_struct *t, int cap)
346{
347	return has_ns_capability_noaudit(t, &init_user_ns, cap);
348}
349EXPORT_SYMBOL(has_capability_noaudit);
350
351static bool ns_capable_common(struct user_namespace *ns,
352			      int cap,
353			      unsigned int opts)
354{
355	int capable;
356
357	if (unlikely(!cap_valid(cap))) {
358		pr_crit("capable() called with invalid cap=%u\n", cap);
359		BUG();
360	}
361
362	capable = security_capable(current_cred(), ns, cap, opts);
 
363	if (capable == 0) {
364		current->flags |= PF_SUPERPRIV;
365		return true;
366	}
367	return false;
368}
369
370/**
371 * ns_capable - Determine if the current task has a superior capability in effect
372 * @ns:  The usernamespace we want the capability in
373 * @cap: The capability to be tested for
374 *
375 * Return true if the current task has the given superior capability currently
376 * available for use, false if not.
377 *
378 * This sets PF_SUPERPRIV on the task if the capability is available on the
379 * assumption that it's about to be used.
380 */
381bool ns_capable(struct user_namespace *ns, int cap)
382{
383	return ns_capable_common(ns, cap, CAP_OPT_NONE);
384}
385EXPORT_SYMBOL(ns_capable);
386
387/**
388 * ns_capable_noaudit - Determine if the current task has a superior capability
389 * (unaudited) in effect
390 * @ns:  The usernamespace we want the capability in
391 * @cap: The capability to be tested for
392 *
393 * Return true if the current task has the given superior capability currently
394 * available for use, false if not.
395 *
396 * This sets PF_SUPERPRIV on the task if the capability is available on the
397 * assumption that it's about to be used.
398 */
399bool ns_capable_noaudit(struct user_namespace *ns, int cap)
400{
401	return ns_capable_common(ns, cap, CAP_OPT_NOAUDIT);
402}
403EXPORT_SYMBOL(ns_capable_noaudit);
404
405/**
406 * ns_capable_setid - Determine if the current task has a superior capability
407 * in effect, while signalling that this check is being done from within a
408 * setid or setgroups syscall.
409 * @ns:  The usernamespace we want the capability in
410 * @cap: The capability to be tested for
411 *
412 * Return true if the current task has the given superior capability currently
413 * available for use, false if not.
414 *
415 * This sets PF_SUPERPRIV on the task if the capability is available on the
416 * assumption that it's about to be used.
417 */
418bool ns_capable_setid(struct user_namespace *ns, int cap)
419{
420	return ns_capable_common(ns, cap, CAP_OPT_INSETID);
421}
422EXPORT_SYMBOL(ns_capable_setid);
423
424/**
425 * capable - Determine if the current task has a superior capability in effect
426 * @cap: The capability to be tested for
427 *
428 * Return true if the current task has the given superior capability currently
429 * available for use, false if not.
430 *
431 * This sets PF_SUPERPRIV on the task if the capability is available on the
432 * assumption that it's about to be used.
433 */
434bool capable(int cap)
435{
436	return ns_capable(&init_user_ns, cap);
437}
438EXPORT_SYMBOL(capable);
439#endif /* CONFIG_MULTIUSER */
440
441/**
442 * file_ns_capable - Determine if the file's opener had a capability in effect
443 * @file:  The file we want to check
444 * @ns:  The usernamespace we want the capability in
445 * @cap: The capability to be tested for
446 *
447 * Return true if task that opened the file had a capability in effect
448 * when the file was opened.
449 *
450 * This does not set PF_SUPERPRIV because the caller may not
451 * actually be privileged.
452 */
453bool file_ns_capable(const struct file *file, struct user_namespace *ns,
454		     int cap)
455{
456
457	if (WARN_ON_ONCE(!cap_valid(cap)))
458		return false;
459
460	if (security_capable(file->f_cred, ns, cap, CAP_OPT_NONE) == 0)
461		return true;
462
463	return false;
464}
465EXPORT_SYMBOL(file_ns_capable);
466
467/**
468 * privileged_wrt_inode_uidgid - Do capabilities in the namespace work over the inode?
469 * @ns: The user namespace in question
470 * @idmap: idmap of the mount @inode was found from
471 * @inode: The inode in question
472 *
473 * Return true if the inode uid and gid are within the namespace.
474 */
475bool privileged_wrt_inode_uidgid(struct user_namespace *ns,
476				 struct mnt_idmap *idmap,
477				 const struct inode *inode)
478{
479	return vfsuid_has_mapping(ns, i_uid_into_vfsuid(idmap, inode)) &&
480	       vfsgid_has_mapping(ns, i_gid_into_vfsgid(idmap, inode));
481}
482
483/**
484 * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
485 * @idmap: idmap of the mount @inode was found from
486 * @inode: The inode in question
487 * @cap: The capability in question
488 *
489 * Return true if the current task has the given capability targeted at
490 * its own user namespace and that the given inode's uid and gid are
491 * mapped into the current user namespace.
492 */
493bool capable_wrt_inode_uidgid(struct mnt_idmap *idmap,
494			      const struct inode *inode, int cap)
495{
496	struct user_namespace *ns = current_user_ns();
497
498	return ns_capable(ns, cap) &&
499	       privileged_wrt_inode_uidgid(ns, idmap, inode);
500}
501EXPORT_SYMBOL(capable_wrt_inode_uidgid);
502
503/**
504 * ptracer_capable - Determine if the ptracer holds CAP_SYS_PTRACE in the namespace
505 * @tsk: The task that may be ptraced
506 * @ns: The user namespace to search for CAP_SYS_PTRACE in
507 *
508 * Return true if the task that is ptracing the current task had CAP_SYS_PTRACE
509 * in the specified user namespace.
510 */
511bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns)
512{
513	int ret = 0;  /* An absent tracer adds no restrictions */
514	const struct cred *cred;
515
516	rcu_read_lock();
517	cred = rcu_dereference(tsk->ptracer_cred);
518	if (cred)
519		ret = security_capable(cred, ns, CAP_SYS_PTRACE,
520				       CAP_OPT_NOAUDIT);
521	rcu_read_unlock();
522	return (ret == 0);
523}