[mirror_ubuntu-zesty-kernel.git] / kernel / capability.c

/*
 * linux/kernel/capability.c
 *
 * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
 *
 * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@kernel.org>
 * 30 May 2002:	Cleanup, Robert M. Love <rml@tech9.net>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/export.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <asm/uaccess.h>

/*
 * Leveraged for setting/resetting capabilities
 */

const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
EXPORT_SYMBOL(__cap_empty_set);

int file_caps_enabled = 1;

static int __init file_caps_disable(char *str)
{
	file_caps_enabled = 0;
	return 1;
}
__setup("no_file_caps", file_caps_disable);

/*
 * More recent versions of libcap are available from:
 *
 *   http://www.kernel.org/pub/linux/libs/security/linux-privs/
 */

static void warn_legacy_capability_use(void)
{
	char name[sizeof(current->comm)];

	pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n",
		     get_task_comm(name, current));
}

/*
 * Version 2 capabilities worked fine, but the linux/capability.h file
 * that accompanied their introduction encouraged their use without
 * the necessary user-space source code changes. As such, we have
 * created a version 3 with equivalent functionality to version 2, but
 * with a header change to protect legacy source code from using
 * version 2 when it wanted to use version 1. If your system has code
 * that trips the following warning, it is using version 2 specific
 * capabilities and may be doing so insecurely.
 *
 * The remedy is to either upgrade your version of libcap (to 2.10+,
 * if the application is linked against it), or recompile your
 * application with modern kernel headers and this warning will go
 * away.
 */

static void warn_deprecated_v2(void)
{
	char name[sizeof(current->comm)];

	pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n",
		     get_task_comm(name, current));
}

/*
 * Version check. Return the number of u32s in each capability flag
 * array, or a negative value on error.
 */
static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
{
	__u32 version;

	if (get_user(version, &header->version))
		return -EFAULT;

	switch (version) {
	case _LINUX_CAPABILITY_VERSION_1:
		warn_legacy_capability_use();
		*tocopy = _LINUX_CAPABILITY_U32S_1;
		break;
	case _LINUX_CAPABILITY_VERSION_2:
		warn_deprecated_v2();
		/*
		 * fall through - v3 is otherwise equivalent to v2.
		 */
	case _LINUX_CAPABILITY_VERSION_3:
		*tocopy = _LINUX_CAPABILITY_U32S_3;
		break;
	default:
		if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
			return -EFAULT;
		return -EINVAL;
	}

	return 0;
}

/*
 * The only thing that can change the capabilities of the current
 * process is the current process. As such, we can't be in this code
 * at the same time as we are in the process of setting capabilities
 * in this process. The net result is that we can limit our use of
 * locks to when we are reading the caps of another process.
 */
static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
				     kernel_cap_t *pIp, kernel_cap_t *pPp)
{
	int ret;

	if (pid && (pid != task_pid_vnr(current))) {
		struct task_struct *target;

		rcu_read_lock();

		target = find_task_by_vpid(pid);
		if (!target)
			ret = -ESRCH;
		else
			ret = security_capget(target, pEp, pIp, pPp);

		rcu_read_unlock();
	} else
		ret = security_capget(current, pEp, pIp, pPp);

	return ret;
}

/**
 * sys_capget - get the capabilities of a given process.
 * @header: pointer to struct that contains capability version and
 *	target pid data
 * @dataptr: pointer to struct that contains the effective, permitted,
 *	and inheritable capabilities that are returned
 *
 * Returns 0 on success and < 0 on error.
 */
SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
{
	int ret = 0;
	pid_t pid;
	unsigned tocopy;
	kernel_cap_t pE, pI, pP;

	ret = cap_validate_magic(header, &tocopy);
	if ((dataptr == NULL) || (ret != 0))
		return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;

	if (get_user(pid, &header->pid))
		return -EFAULT;

	if (pid < 0)
		return -EINVAL;

	ret = cap_get_target_pid(pid, &pE, &pI, &pP);
	if (!ret) {
		struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
		unsigned i;

		for (i = 0; i < tocopy; i++) {
			kdata[i].effective = pE.cap[i];
			kdata[i].permitted = pP.cap[i];
			kdata[i].inheritable = pI.cap[i];
		}

		/*
		 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
		 * we silently drop the upper capabilities here. This
		 * has the effect of making older libcap
		 * implementations implicitly drop upper capability
		 * bits when they perform a: capget/modify/capset
		 * sequence.
		 *
		 * This behavior is considered fail-safe
		 * behavior. Upgrading the application to a newer
		 * version of libcap will enable access to the newer
		 * capabilities.
		 *
		 * An alternative would be to return an error here
		 * (-ERANGE), but that causes legacy applications to
		 * unexpectedly fail; the capget/modify/capset aborts
		 * before modification is attempted and the application
		 * fails.
		 */
		if (copy_to_user(dataptr, kdata, tocopy
				 * sizeof(struct __user_cap_data_struct))) {
			return -EFAULT;
		}
	}

	return ret;
}

/**
 * sys_capset - set capabilities for a process or (*) a group of processes
 * @header: pointer to struct that contains capability version and
 *	target pid data
 * @data: pointer to struct that contains the effective, permitted,
 *	and inheritable capabilities
 *
 * Set capabilities for the current process only.  The ability to any other
 * process(es) has been deprecated and removed.
 *
 * The restrictions on setting capabilities are specified as:
 *
 * I: any raised capabilities must be a subset of the old permitted
 * P: any raised capabilities must be a subset of the old permitted
 * E: must be set to a subset of new permitted
 *
 * Returns 0 on success and < 0 on error.
 */
SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
{
	struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
	unsigned i, tocopy, copybytes;
	kernel_cap_t inheritable, permitted, effective;
	struct cred *new;
	int ret;
	pid_t pid;

	ret = cap_validate_magic(header, &tocopy);
	if (ret != 0)
		return ret;

	if (get_user(pid, &header->pid))
		return -EFAULT;

	/* may only affect current now */
	if (pid != 0 && pid != task_pid_vnr(current))
		return -EPERM;

	copybytes = tocopy * sizeof(struct __user_cap_data_struct);
	if (copybytes > sizeof(kdata))
		return -EFAULT;

	if (copy_from_user(&kdata, data, copybytes))
		return -EFAULT;

	for (i = 0; i < tocopy; i++) {
		effective.cap[i] = kdata[i].effective;
		permitted.cap[i] = kdata[i].permitted;
		inheritable.cap[i] = kdata[i].inheritable;
	}
	while (i < _KERNEL_CAPABILITY_U32S) {
		effective.cap[i] = 0;
		permitted.cap[i] = 0;
		inheritable.cap[i] = 0;
		i++;
	}

	new = prepare_creds();
	if (!new)
		return -ENOMEM;

	ret = security_capset(new, current_cred(),
			      &effective, &inheritable, &permitted);
	if (ret < 0)
		goto error;

	audit_log_capset(new, current_cred());

	return commit_creds(new);

error:
	abort_creds(new);
	return ret;
}

/**
 * has_ns_capability - Does a task have a capability in a specific user ns
 * @t: The task in question
 * @ns: target user namespace
 * @cap: The capability to be tested for
 *
 * Return true if the specified task has the given superior capability
 * currently in effect to the specified user namespace, false if not.
 *
 * Note that this does not set PF_SUPERPRIV on the task.
 */
bool has_ns_capability(struct task_struct *t,
		       struct user_namespace *ns, int cap)
{
	int ret;

	rcu_read_lock();
	ret = security_capable(__task_cred(t), ns, cap);
	rcu_read_unlock();

	return (ret == 0);
}

/**
 * has_capability - Does a task have a capability in init_user_ns
 * @t: The task in question
 * @cap: The capability to be tested for
 *
 * Return true if the specified task has the given superior capability
 * currently in effect to the initial user namespace, false if not.
 *
 * Note that this does not set PF_SUPERPRIV on the task.
 */
bool has_capability(struct task_struct *t, int cap)
{
	return has_ns_capability(t, &init_user_ns, cap);
}

/**
 * has_ns_capability_noaudit - Does a task have a capability (unaudited)
 * in a specific user ns.
 * @t: The task in question
 * @ns: target user namespace
 * @cap: The capability to be tested for
 *
 * Return true if the specified task has the given superior capability
 * currently in effect to the specified user namespace, false if not.
 * Do not write an audit message for the check.
 *
 * Note that this does not set PF_SUPERPRIV on the task.
 */
bool has_ns_capability_noaudit(struct task_struct *t,
			       struct user_namespace *ns, int cap)
{
	int ret;

	rcu_read_lock();
	ret = security_capable_noaudit(__task_cred(t), ns, cap);
	rcu_read_unlock();

	return (ret == 0);
}

/**
 * has_capability_noaudit - Does a task have a capability (unaudited) in the
 * initial user ns
 * @t: The task in question
 * @cap: The capability to be tested for
 *
 * Return true if the specified task has the given superior capability
 * currently in effect to init_user_ns, false if not.  Don't write an
 * audit message for the check.
 *
 * Note that this does not set PF_SUPERPRIV on the task.
 */
bool has_capability_noaudit(struct task_struct *t, int cap)
{
	return has_ns_capability_noaudit(t, &init_user_ns, cap);
}

/**
 * ns_capable - Determine if the current task has a superior capability in effect
 * @ns:  The usernamespace we want the capability in
 * @cap: The capability to be tested for
 *
 * Return true if the current task has the given superior capability currently
 * available for use, false if not.
 *
 * This sets PF_SUPERPRIV on the task if the capability is available on the
 * assumption that it's about to be used.
 */
bool ns_capable(struct user_namespace *ns, int cap)
{
	if (unlikely(!cap_valid(cap))) {
		pr_crit("capable() called with invalid cap=%u\n", cap);
		BUG();
	}

	if (security_capable(current_cred(), ns, cap) == 0) {
		current->flags |= PF_SUPERPRIV;
		return true;
	}
	return false;
}
EXPORT_SYMBOL(ns_capable);

/**
 * file_ns_capable - Determine if the file's opener had a capability in effect
 * @file:  The file we want to check
 * @ns:  The usernamespace we want the capability in
 * @cap: The capability to be tested for
 *
 * Return true if task that opened the file had a capability in effect
 * when the file was opened.
 *
 * This does not set PF_SUPERPRIV because the caller may not
 * actually be privileged.
 */
bool file_ns_capable(const struct file *file, struct user_namespace *ns,
		     int cap)
{
	if (WARN_ON_ONCE(!cap_valid(cap)))
		return false;

	if (security_capable(file->f_cred, ns, cap) == 0)
		return true;

	return false;
}
EXPORT_SYMBOL(file_ns_capable);

/**
 * capable - Determine if the current task has a superior capability in effect
 * @cap: The capability to be tested for
 *
 * Return true if the current task has the given superior capability currently
 * available for use, false if not.
 *
 * This sets PF_SUPERPRIV on the task if the capability is available on the
 * assumption that it's about to be used.
 */
bool capable(int cap)
{
	return ns_capable(&init_user_ns, cap);
}
EXPORT_SYMBOL(capable);

/**
 * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
 * @inode: The inode in question
 * @cap: The capability in question
 *
 * Return true if the current task has the given capability targeted at
 * its own user namespace and that the given inode's uid and gid are
 * mapped into the current user namespace.
 */
bool capable_wrt_inode_uidgid(const struct inode *inode, int cap)
{
	struct user_namespace *ns = current_user_ns();

	return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid) &&
		kgid_has_mapping(ns, inode->i_gid);
}
EXPORT_SYMBOL(capable_wrt_inode_uidgid);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/kernel/capability.c
	3	*
	4	* Copyright (C) 1997 Andrew Main <zefram@fysh.org>
	5	*
72c2d582	6	* Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org>
1da177e4	7	* 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
314f70fd	8	*/
1da177e4	9
f5645d35 JP	10	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
f5645d35 JP	11
e68b75a0	12	#include <linux/audit.h>
c59ede7b	13	#include <linux/capability.h>
1da177e4	14	#include <linux/mm.h>
9984de1a	15	#include <linux/export.h>
1da177e4 LT	16	#include <linux/security.h>
1da177e4 LT	17	#include <linux/syscalls.h>
b460cbc5	18	#include <linux/pid_namespace.h>
3486740a	19	#include <linux/user_namespace.h>
1da177e4	20	#include <asm/uaccess.h>
1da177e4	21
e338d263 AM	22	/*
	23	* Leveraged for setting/resetting capabilities
	24	*/
	25
	26	const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
e338d263	27	EXPORT_SYMBOL(__cap_empty_set);
e338d263	28
1f29fae2 SH	29	int file_caps_enabled = 1;
	30
	31	static 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);
1f29fae2	37
e338d263 AM	38	/*
	39	* More recent versions of libcap are available from:
	40	*
	41	* http://www.kernel.org/pub/linux/libs/security/linux-privs/
	42	*/
	43
	44	static void warn_legacy_capability_use(void)
	45	{
f5645d35 JP	46	char name[sizeof(current->comm)];
	47
	48	pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n",
	49	get_task_comm(name, current));
e338d263 AM	50	}
e338d263 AM	51
ca05a99a AM	52	/*
	53	* Version 2 capabilities worked fine, but the linux/capability.h file
	54	* that accompanied their introduction encouraged their use without
	55	* the necessary user-space source code changes. As such, we have
	56	* created a version 3 with equivalent functionality to version 2, but
	57	* with a header change to protect legacy source code from using
	58	* version 2 when it wanted to use version 1. If your system has code
	59	* that trips the following warning, it is using version 2 specific
	60	* capabilities and may be doing so insecurely.
	61	*
	62	* The remedy is to either upgrade your version of libcap (to 2.10+,
	63	* if the application is linked against it), or recompile your
	64	* application with modern kernel headers and this warning will go
	65	* away.
	66	*/
	67
	68	static void warn_deprecated_v2(void)
	69	{
f5645d35	70	char name[sizeof(current->comm)];
ca05a99a	71
f5645d35 JP	72	pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n",
f5645d35 JP	73	get_task_comm(name, current));
ca05a99a AM	74	}
	75
	76	/*
	77	* Version check. Return the number of u32s in each capability flag
	78	* array, or a negative value on error.
	79	*/
	80	static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
	81	{
	82	__u32 version;
	83
	84	if (get_user(version, &header->version))
	85	return -EFAULT;
	86
	87	switch (version) {
	88	case _LINUX_CAPABILITY_VERSION_1:
	89	warn_legacy_capability_use();
	90	*tocopy = _LINUX_CAPABILITY_U32S_1;
	91	break;
	92	case _LINUX_CAPABILITY_VERSION_2:
	93	warn_deprecated_v2();
	94	/*
	95	* fall through - v3 is otherwise equivalent to v2.
	96	*/
	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
ab763c71	109	/*
d84f4f99 DH	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.
ab763c71 AM	115	*/
	116	static 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
86fc80f1	124	rcu_read_lock();
ab763c71 AM	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
86fc80f1	132	rcu_read_unlock();
ab763c71 AM	133	} else
	134	ret = security_capget(current, pEp, pIp, pPp);
	135
	136	return ret;
	137	}
	138
207a7ba8	139	/**
1da177e4	140	* sys_capget - get the capabilities of a given process.
207a7ba8 RD	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.
1da177e4	147	*/
b290ebe2	148	SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
1da177e4	149	{
314f70fd DW	150	int ret = 0;
314f70fd DW	151	pid_t pid;
e338d263 AM	152	unsigned tocopy;
e338d263 AM	153	kernel_cap_t pE, pI, pP;
314f70fd	154
ca05a99a	155	ret = cap_validate_magic(header, &tocopy);
c4a5af54 AM	156	if ((dataptr == NULL) \|\| (ret != 0))
c4a5af54 AM	157	return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;
1da177e4	158
314f70fd DW	159	if (get_user(pid, &header->pid))
314f70fd DW	160	return -EFAULT;
1da177e4	161
314f70fd DW	162	if (pid < 0)
314f70fd DW	163	return -EINVAL;
1da177e4	164
ab763c71	165	ret = cap_get_target_pid(pid, &pE, &pI, &pP);
e338d263	166	if (!ret) {
ca05a99a	167	struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
e338d263 AM	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	/*
ca05a99a	177	* Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
e338d263 AM	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
a6c8c690	191	* unexpectedly fail; the capget/modify/capset aborts
e338d263 AM	192	* before modification is attempted and the application
	193	* fails.
	194	*/
e338d263 AM	195	if (copy_to_user(dataptr, kdata, tocopy
	196	* sizeof(struct __user_cap_data_struct))) {
	197	return -EFAULT;
	198	}
	199	}
1da177e4	200
314f70fd	201	return ret;
1da177e4 LT	202	}
1da177e4 LT	203
207a7ba8	204	/**
ab763c71	205	* sys_capset - set capabilities for a process or (*) a group of processes
207a7ba8 RD	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	*
1cdcbec1 DH	211	* Set capabilities for the current process only. The ability to any other
1cdcbec1 DH	212	* process(es) has been deprecated and removed.
1da177e4 LT	213	*
	214	* The restrictions on setting capabilities are specified as:
	215	*
1cdcbec1 DH	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
207a7ba8 RD	219	*
207a7ba8 RD	220	* Returns 0 on success and < 0 on error.
1da177e4	221	*/
b290ebe2	222	SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
1da177e4	223	{
ca05a99a	224	struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
825332e4	225	unsigned i, tocopy, copybytes;
314f70fd	226	kernel_cap_t inheritable, permitted, effective;
d84f4f99	227	struct cred *new;
314f70fd DW	228	int ret;
	229	pid_t pid;
	230
ca05a99a AM	231	ret = cap_validate_magic(header, &tocopy);
	232	if (ret != 0)
	233	return ret;
314f70fd DW	234
	235	if (get_user(pid, &header->pid))
	236	return -EFAULT;
	237
1cdcbec1 DH	238	/* may only affect current now */
	239	if (pid != 0 && pid != task_pid_vnr(current))
	240	return -EPERM;
	241
825332e4 AV	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))
314f70fd	247	return -EFAULT;
e338d263 AM	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	}
ca05a99a	254	while (i < _KERNEL_CAPABILITY_U32S) {
e338d263 AM	255	effective.cap[i] = 0;
	256	permitted.cap[i] = 0;
	257	inheritable.cap[i] = 0;
	258	i++;
	259	}
314f70fd	260
d84f4f99 DH	261	new = prepare_creds();
	262	if (!new)
	263	return -ENOMEM;
	264
	265	ret = security_capset(new, current_cred(),
	266	&effective, &inheritable, &permitted);
	267	if (ret < 0)
	268	goto error;
	269
ca24a23e	270	audit_log_capset(new, current_cred());
e68b75a0	271
d84f4f99 DH	272	return commit_creds(new);
	273
	274	error:
	275	abort_creds(new);
314f70fd	276	return ret;
1da177e4	277	}
12b5989b	278
3263245d	279	/**
25e75703	280	* has_ns_capability - Does a task have a capability in a specific user ns
3263245d	281	* @t: The task in question
25e75703	282	* @ns: target user namespace
3263245d SH	283	* @cap: The capability to be tested for
	284	*
	285	* Return true if the specified task has the given superior capability
25e75703	286	* currently in effect to the specified user namespace, false if not.
3263245d SH	287	*
	288	* Note that this does not set PF_SUPERPRIV on the task.
	289	*/
25e75703 EP	290	bool has_ns_capability(struct task_struct *t,
25e75703 EP	291	struct user_namespace *ns, int cap)
3263245d	292	{
2920a840 EP	293	int ret;
	294
	295	rcu_read_lock();
25e75703	296	ret = security_capable(__task_cred(t), ns, cap);
2920a840	297	rcu_read_unlock();
3263245d SH	298
	299	return (ret == 0);
	300	}
	301
	302	/**
25e75703	303	* has_capability - Does a task have a capability in init_user_ns
3263245d	304	* @t: The task in question
3263245d SH	305	* @cap: The capability to be tested for
	306	*
	307	* Return true if the specified task has the given superior capability
25e75703	308	* currently in effect to the initial user namespace, false if not.
3263245d SH	309	*
	310	* Note that this does not set PF_SUPERPRIV on the task.
	311	*/
25e75703	312	bool has_capability(struct task_struct *t, int cap)
3263245d	313	{
25e75703	314	return has_ns_capability(t, &init_user_ns, cap);
3263245d SH	315	}
	316
	317	/**
7b61d648 EP	318	* has_ns_capability_noaudit - Does a task have a capability (unaudited)
7b61d648 EP	319	* in a specific user ns.
3263245d	320	* @t: The task in question
7b61d648	321	* @ns: target user namespace
3263245d SH	322	* @cap: The capability to be tested for
	323	*
	324	* Return true if the specified task has the given superior capability
7b61d648 EP	325	* currently in effect to the specified user namespace, false if not.
7b61d648 EP	326	* Do not write an audit message for the check.
3263245d SH	327	*
	328	* Note that this does not set PF_SUPERPRIV on the task.
	329	*/
7b61d648 EP	330	bool has_ns_capability_noaudit(struct task_struct *t,
7b61d648 EP	331	struct user_namespace *ns, int cap)
3263245d	332	{
2920a840 EP	333	int ret;
	334
	335	rcu_read_lock();
7b61d648	336	ret = security_capable_noaudit(__task_cred(t), ns, cap);
2920a840	337	rcu_read_unlock();
3263245d SH	338
	339	return (ret == 0);
	340	}
	341
5cd9c58f	342	/**
7b61d648 EP	343	* has_capability_noaudit - Does a task have a capability (unaudited) in the
	344	* initial user ns
	345	* @t: The task in question
5cd9c58f DH	346	* @cap: The capability to be tested for
5cd9c58f DH	347	*
7b61d648 EP	348	* Return true if the specified task has the given superior capability
	349	* currently in effect to init_user_ns, false if not. Don't write an
	350	* audit message for the check.
5cd9c58f	351	*
7b61d648	352	* Note that this does not set PF_SUPERPRIV on the task.
5cd9c58f	353	*/
7b61d648	354	bool has_capability_noaudit(struct task_struct *t, int cap)
3486740a	355	{
7b61d648	356	return has_ns_capability_noaudit(t, &init_user_ns, cap);
3486740a	357	}
3486740a SH	358
	359	/**
	360	* ns_capable - Determine if the current task has a superior capability in effect
	361	* @ns: The usernamespace we want the capability in
	362	* @cap: The capability to be tested for
	363	*
	364	* Return true if the current task has the given superior capability currently
	365	* available for use, false if not.
	366	*
	367	* This sets PF_SUPERPRIV on the task if the capability is available on the
	368	* assumption that it's about to be used.
	369	*/
	370	bool ns_capable(struct user_namespace *ns, int cap)
12b5989b	371	{
637d32dc	372	if (unlikely(!cap_valid(cap))) {
f5645d35	373	pr_crit("capable() called with invalid cap=%u\n", cap);
637d32dc EP	374	BUG();
	375	}
	376
951880e6	377	if (security_capable(current_cred(), ns, cap) == 0) {
5cd9c58f	378	current->flags \|= PF_SUPERPRIV;
3486740a	379	return true;
12b5989b	380	}
3486740a	381	return false;
12b5989b	382	}
3486740a SH	383	EXPORT_SYMBOL(ns_capable);
3486740a SH	384
935d8aab LT	385	/**
	386	* file_ns_capable - Determine if the file's opener had a capability in effect
	387	* @file: The file we want to check
	388	* @ns: The usernamespace we want the capability in
	389	* @cap: The capability to be tested for
	390	*
	391	* Return true if task that opened the file had a capability in effect
	392	* when the file was opened.
	393	*
	394	* This does not set PF_SUPERPRIV because the caller may not
	395	* actually be privileged.
	396	*/
a6c8c690 FF	397	bool file_ns_capable(const struct file file, struct user_namespace ns,
a6c8c690 FF	398	int cap)
935d8aab LT	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	}
	408	EXPORT_SYMBOL(file_ns_capable);
	409
3486740a	410	/**
105ddf49 EP	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.
3486740a	416	*
105ddf49 EP	417	* This sets PF_SUPERPRIV on the task if the capability is available on the
105ddf49 EP	418	* assumption that it's about to be used.
3486740a	419	*/
105ddf49	420	bool capable(int cap)
3486740a	421	{
105ddf49	422	return ns_capable(&init_user_ns, cap);
3486740a	423	}
105ddf49	424	EXPORT_SYMBOL(capable);
47a150ed	425
1a48e2ac	426	/**
23adbe12	427	* capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
1a48e2ac EB	428	* @inode: The inode in question
	429	* @cap: The capability in question
	430	*
23adbe12 AL	431	* Return true if the current task has the given capability targeted at
	432	* its own user namespace and that the given inode's uid and gid are
	433	* mapped into the current user namespace.
1a48e2ac	434	*/
23adbe12	435	bool capable_wrt_inode_uidgid(const struct inode *inode, int cap)
1a48e2ac EB	436	{
	437	struct user_namespace *ns = current_user_ns();
	438
23adbe12 AL	439	return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid) &&
23adbe12 AL	440	kgid_has_mapping(ns, inode->i_gid);
1a48e2ac	441	}
23adbe12	442	EXPORT_SYMBOL(capable_wrt_inode_uidgid);