[mirror_ubuntu-focal-kernel.git] / security / yama / yama_lsm.c

/*
 * Yama Linux Security Module
 *
 * Author: Kees Cook <keescook@chromium.org>
 *
 * Copyright (C) 2010 Canonical, Ltd.
 * Copyright (C) 2011 The Chromium OS Authors.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2, as
 * published by the Free Software Foundation.
 *
 */

#include <linux/security.h>
#include <linux/sysctl.h>
#include <linux/ptrace.h>
#include <linux/prctl.h>
#include <linux/ratelimit.h>

#define YAMA_SCOPE_DISABLED	0
#define YAMA_SCOPE_RELATIONAL	1
#define YAMA_SCOPE_CAPABILITY	2
#define YAMA_SCOPE_NO_ATTACH	3

static int ptrace_scope = YAMA_SCOPE_RELATIONAL;

/* describe a ptrace relationship for potential exception */
struct ptrace_relation {
	struct task_struct *tracer;
	struct task_struct *tracee;
	struct list_head node;
	struct rcu_head rcu;
};

static LIST_HEAD(ptracer_relations);
static DEFINE_SPINLOCK(ptracer_relations_lock);

/**
 * yama_ptracer_add - add/replace an exception for this tracer/tracee pair
 * @tracer: the task_struct of the process doing the ptrace
 * @tracee: the task_struct of the process to be ptraced
 *
 * Each tracee can have, at most, one tracer registered. Each time this
 * is called, the prior registered tracer will be replaced for the tracee.
 *
 * Returns 0 if relationship was added, -ve on error.
 */
static int yama_ptracer_add(struct task_struct *tracer,
			    struct task_struct *tracee)
{
	struct ptrace_relation *relation, *added;

	added = kmalloc(sizeof(*added), GFP_KERNEL);
	if (!added)
		return -ENOMEM;

	added->tracee = tracee;
	added->tracer = tracer;

	spin_lock_bh(&ptracer_relations_lock);
	rcu_read_lock();
	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
		if (relation->tracee == tracee) {
			list_replace_rcu(&relation->node, &added->node);
			kfree_rcu(relation, rcu);
			goto out;
		}
	}

	list_add_rcu(&added->node, &ptracer_relations);

out:
	rcu_read_unlock();
	spin_unlock_bh(&ptracer_relations_lock);
	return 0;
}

/**
 * yama_ptracer_del - remove exceptions related to the given tasks
 * @tracer: remove any relation where tracer task matches
 * @tracee: remove any relation where tracee task matches
 */
static void yama_ptracer_del(struct task_struct *tracer,
			     struct task_struct *tracee)
{
	struct ptrace_relation *relation;

	spin_lock_bh(&ptracer_relations_lock);
	rcu_read_lock();
	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
		if (relation->tracee == tracee ||
		    (tracer && relation->tracer == tracer)) {
			list_del_rcu(&relation->node);
			kfree_rcu(relation, rcu);
		}
	}
	rcu_read_unlock();
	spin_unlock_bh(&ptracer_relations_lock);
}

/**
 * yama_task_free - check for task_pid to remove from exception list
 * @task: task being removed
 */
void yama_task_free(struct task_struct *task)
{
	yama_ptracer_del(task, task);
}

/**
 * yama_task_prctl - check for Yama-specific prctl operations
 * @option: operation
 * @arg2: argument
 * @arg3: argument
 * @arg4: argument
 * @arg5: argument
 *
 * Return 0 on success, -ve on error.  -ENOSYS is returned when Yama
 * does not handle the given option.
 */
int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
			   unsigned long arg4, unsigned long arg5)
{
	int rc;
	struct task_struct *myself = current;

	rc = cap_task_prctl(option, arg2, arg3, arg4, arg5);
	if (rc != -ENOSYS)
		return rc;

	switch (option) {
	case PR_SET_PTRACER:
		/* Since a thread can call prctl(), find the group leader
		 * before calling _add() or _del() on it, since we want
		 * process-level granularity of control. The tracer group
		 * leader checking is handled later when walking the ancestry
		 * at the time of PTRACE_ATTACH check.
		 */
		rcu_read_lock();
		if (!thread_group_leader(myself))
			myself = rcu_dereference(myself->group_leader);
		get_task_struct(myself);
		rcu_read_unlock();

		if (arg2 == 0) {
			yama_ptracer_del(NULL, myself);
			rc = 0;
		} else if (arg2 == PR_SET_PTRACER_ANY || (int)arg2 == -1) {
			rc = yama_ptracer_add(NULL, myself);
		} else {
			struct task_struct *tracer;

			rcu_read_lock();
			tracer = find_task_by_vpid(arg2);
			if (tracer)
				get_task_struct(tracer);
			else
				rc = -EINVAL;
			rcu_read_unlock();

			if (tracer) {
				rc = yama_ptracer_add(tracer, myself);
				put_task_struct(tracer);
			}
		}

		put_task_struct(myself);
		break;
	}

	return rc;
}

/**
 * task_is_descendant - walk up a process family tree looking for a match
 * @parent: the process to compare against while walking up from child
 * @child: the process to start from while looking upwards for parent
 *
 * Returns 1 if child is a descendant of parent, 0 if not.
 */
static int task_is_descendant(struct task_struct *parent,
			      struct task_struct *child)
{
	int rc = 0;
	struct task_struct *walker = child;

	if (!parent || !child)
		return 0;

	rcu_read_lock();
	if (!thread_group_leader(parent))
		parent = rcu_dereference(parent->group_leader);
	while (walker->pid > 0) {
		if (!thread_group_leader(walker))
			walker = rcu_dereference(walker->group_leader);
		if (walker == parent) {
			rc = 1;
			break;
		}
		walker = rcu_dereference(walker->real_parent);
	}
	rcu_read_unlock();

	return rc;
}

/**
 * ptracer_exception_found - tracer registered as exception for this tracee
 * @tracer: the task_struct of the process attempting ptrace
 * @tracee: the task_struct of the process to be ptraced
 *
 * Returns 1 if tracer has is ptracer exception ancestor for tracee.
 */
static int ptracer_exception_found(struct task_struct *tracer,
				   struct task_struct *tracee)
{
	int rc = 0;
	struct ptrace_relation *relation;
	struct task_struct *parent = NULL;
	bool found = false;

	rcu_read_lock();
	if (!thread_group_leader(tracee))
		tracee = rcu_dereference(tracee->group_leader);
	list_for_each_entry_rcu(relation, &ptracer_relations, node)
		if (relation->tracee == tracee) {
			parent = relation->tracer;
			found = true;
			break;
		}

	if (found && (parent == NULL || task_is_descendant(parent, tracer)))
		rc = 1;
	rcu_read_unlock();

	return rc;
}

/**
 * yama_ptrace_access_check - validate PTRACE_ATTACH calls
 * @child: task that current task is attempting to ptrace
 * @mode: ptrace attach mode
 *
 * Returns 0 if following the ptrace is allowed, -ve on error.
 */
int yama_ptrace_access_check(struct task_struct *child,
				    unsigned int mode)
{
	int rc;

	/* If standard caps disallows it, so does Yama.  We should
	 * only tighten restrictions further.
	 */
	rc = cap_ptrace_access_check(child, mode);
	if (rc)
		return rc;

	/* require ptrace target be a child of ptracer on attach */
	if (mode == PTRACE_MODE_ATTACH) {
		switch (ptrace_scope) {
		case YAMA_SCOPE_DISABLED:
			/* No additional restrictions. */
			break;
		case YAMA_SCOPE_RELATIONAL:
			if (!task_is_descendant(current, child) &&
			    !ptracer_exception_found(current, child) &&
			    !ns_capable(task_user_ns(child), CAP_SYS_PTRACE))
				rc = -EPERM;
			break;
		case YAMA_SCOPE_CAPABILITY:
			if (!ns_capable(task_user_ns(child), CAP_SYS_PTRACE))
				rc = -EPERM;
			break;
		case YAMA_SCOPE_NO_ATTACH:
		default:
			rc = -EPERM;
			break;
		}
	}

	if (rc) {
		printk_ratelimited(KERN_NOTICE
			"ptrace of pid %d was attempted by: %s (pid %d)\n",
			child->pid, current->comm, current->pid);
	}

	return rc;
}

/**
 * yama_ptrace_traceme - validate PTRACE_TRACEME calls
 * @parent: task that will become the ptracer of the current task
 *
 * Returns 0 if following the ptrace is allowed, -ve on error.
 */
int yama_ptrace_traceme(struct task_struct *parent)
{
	int rc;

	/* If standard caps disallows it, so does Yama.  We should
	 * only tighten restrictions further.
	 */
	rc = cap_ptrace_traceme(parent);
	if (rc)
		return rc;

	/* Only disallow PTRACE_TRACEME on more aggressive settings. */
	switch (ptrace_scope) {
	case YAMA_SCOPE_CAPABILITY:
		if (!ns_capable(task_user_ns(parent), CAP_SYS_PTRACE))
			rc = -EPERM;
		break;
	case YAMA_SCOPE_NO_ATTACH:
		rc = -EPERM;
		break;
	}

	if (rc) {
		printk_ratelimited(KERN_NOTICE
			"ptraceme of pid %d was attempted by: %s (pid %d)\n",
			current->pid, parent->comm, parent->pid);
	}

	return rc;
}

#ifndef CONFIG_SECURITY_YAMA_STACKED
static struct security_operations yama_ops = {
	.name =			"yama",

	.ptrace_access_check =	yama_ptrace_access_check,
	.ptrace_traceme =	yama_ptrace_traceme,
	.task_prctl =		yama_task_prctl,
	.task_free =		yama_task_free,
};
#endif

#ifdef CONFIG_SYSCTL
static int yama_dointvec_minmax(struct ctl_table *table, int write,
				void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int rc;

	if (write && !capable(CAP_SYS_PTRACE))
		return -EPERM;

	rc = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
	if (rc)
		return rc;

	/* Lock the max value if it ever gets set. */
	if (write && *(int *)table->data == *(int *)table->extra2)
		table->extra1 = table->extra2;

	return rc;
}

static int zero;
static int max_scope = YAMA_SCOPE_NO_ATTACH;

struct ctl_path yama_sysctl_path[] = {
	{ .procname = "kernel", },
	{ .procname = "yama", },
	{ }
};

static struct ctl_table yama_sysctl_table[] = {
	{
		.procname       = "ptrace_scope",
		.data           = &ptrace_scope,
		.maxlen         = sizeof(int),
		.mode           = 0644,
		.proc_handler   = yama_dointvec_minmax,
		.extra1         = &zero,
		.extra2         = &max_scope,
	},
	{ }
};
#endif /* CONFIG_SYSCTL */

static __init int yama_init(void)
{
#ifndef CONFIG_SECURITY_YAMA_STACKED
	if (!security_module_enable(&yama_ops))
		return 0;
#endif

	printk(KERN_INFO "Yama: becoming mindful.\n");

#ifndef CONFIG_SECURITY_YAMA_STACKED
	if (register_security(&yama_ops))
		panic("Yama: kernel registration failed.\n");
#endif

#ifdef CONFIG_SYSCTL
	if (!register_sysctl_paths(yama_sysctl_path, yama_sysctl_table))
		panic("Yama: sysctl registration failed.\n");
#endif

	return 0;
}

security_initcall(yama_init);
Commit	Line	Data
2d514487 KC	1	/*
	2	* Yama Linux Security Module
	3	*
	4	* Author: Kees Cook <keescook@chromium.org>
	5	*
	6	* Copyright (C) 2010 Canonical, Ltd.
	7	* Copyright (C) 2011 The Chromium OS Authors.
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2, as
	11	* published by the Free Software Foundation.
	12	*
	13	*/
	14
	15	#include <linux/security.h>
	16	#include <linux/sysctl.h>
	17	#include <linux/ptrace.h>
	18	#include <linux/prctl.h>
	19	#include <linux/ratelimit.h>
	20
389da25f KC	21	#define YAMA_SCOPE_DISABLED 0
	22	#define YAMA_SCOPE_RELATIONAL 1
	23	#define YAMA_SCOPE_CAPABILITY 2
	24	#define YAMA_SCOPE_NO_ATTACH 3
	25
	26	static int ptrace_scope = YAMA_SCOPE_RELATIONAL;
2d514487 KC	27
	28	/* describe a ptrace relationship for potential exception */
	29	struct ptrace_relation {
	30	struct task_struct *tracer;
	31	struct task_struct *tracee;
	32	struct list_head node;
93b69d43	33	struct rcu_head rcu;
2d514487 KC	34	};
	35
	36	static LIST_HEAD(ptracer_relations);
	37	static DEFINE_SPINLOCK(ptracer_relations_lock);
	38
	39	/**
	40	* yama_ptracer_add - add/replace an exception for this tracer/tracee pair
	41	* @tracer: the task_struct of the process doing the ptrace
	42	* @tracee: the task_struct of the process to be ptraced
	43	*
	44	* Each tracee can have, at most, one tracer registered. Each time this
	45	* is called, the prior registered tracer will be replaced for the tracee.
	46	*
	47	* Returns 0 if relationship was added, -ve on error.
	48	*/
	49	static int yama_ptracer_add(struct task_struct *tracer,
	50	struct task_struct *tracee)
	51	{
93b69d43	52	struct ptrace_relation relation, added;
2d514487 KC	53
	54	added = kmalloc(sizeof(*added), GFP_KERNEL);
	55	if (!added)
	56	return -ENOMEM;
	57
93b69d43 KC	58	added->tracee = tracee;
	59	added->tracer = tracer;
	60
2d514487	61	spin_lock_bh(&ptracer_relations_lock);
93b69d43 KC	62	rcu_read_lock();
	63	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
	64	if (relation->tracee == tracee) {
	65	list_replace_rcu(&relation->node, &added->node);
	66	kfree_rcu(relation, rcu);
	67	goto out;
2d514487	68	}
2d514487	69	}
2d514487	70
93b69d43	71	list_add_rcu(&added->node, &ptracer_relations);
2d514487	72
93b69d43 KC	73	out:
	74	rcu_read_unlock();
	75	spin_unlock_bh(&ptracer_relations_lock);
	76	return 0;
2d514487 KC	77	}
	78
	79	/**
	80	* yama_ptracer_del - remove exceptions related to the given tasks
	81	* @tracer: remove any relation where tracer task matches
	82	* @tracee: remove any relation where tracee task matches
	83	*/
	84	static void yama_ptracer_del(struct task_struct *tracer,
	85	struct task_struct *tracee)
	86	{
93b69d43	87	struct ptrace_relation *relation;
2d514487 KC	88
2d514487 KC	89	spin_lock_bh(&ptracer_relations_lock);
93b69d43 KC	90	rcu_read_lock();
93b69d43 KC	91	list_for_each_entry_rcu(relation, &ptracer_relations, node) {
2d514487	92	if (relation->tracee == tracee \|\|
bf06189e	93	(tracer && relation->tracer == tracer)) {
93b69d43 KC	94	list_del_rcu(&relation->node);
93b69d43 KC	95	kfree_rcu(relation, rcu);
2d514487	96	}
93b69d43 KC	97	}
93b69d43 KC	98	rcu_read_unlock();
2d514487 KC	99	spin_unlock_bh(&ptracer_relations_lock);
	100	}
	101
	102	/**
	103	* yama_task_free - check for task_pid to remove from exception list
	104	* @task: task being removed
	105	*/
c6993e4a	106	void yama_task_free(struct task_struct *task)
2d514487 KC	107	{
	108	yama_ptracer_del(task, task);
	109	}
	110
	111	/**
	112	* yama_task_prctl - check for Yama-specific prctl operations
	113	* @option: operation
	114	* @arg2: argument
	115	* @arg3: argument
	116	* @arg4: argument
	117	* @arg5: argument
	118	*
	119	* Return 0 on success, -ve on error. -ENOSYS is returned when Yama
	120	* does not handle the given option.
	121	*/
c6993e4a	122	int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
2d514487 KC	123	unsigned long arg4, unsigned long arg5)
	124	{
	125	int rc;
	126	struct task_struct *myself = current;
	127
	128	rc = cap_task_prctl(option, arg2, arg3, arg4, arg5);
	129	if (rc != -ENOSYS)
	130	return rc;
	131
	132	switch (option) {
	133	case PR_SET_PTRACER:
	134	/* Since a thread can call prctl(), find the group leader
	135	* before calling _add() or _del() on it, since we want
	136	* process-level granularity of control. The tracer group
	137	* leader checking is handled later when walking the ancestry
	138	* at the time of PTRACE_ATTACH check.
	139	*/
	140	rcu_read_lock();
	141	if (!thread_group_leader(myself))
	142	myself = rcu_dereference(myself->group_leader);
	143	get_task_struct(myself);
	144	rcu_read_unlock();
	145
	146	if (arg2 == 0) {
	147	yama_ptracer_del(NULL, myself);
	148	rc = 0;
2e4930eb	149	} else if (arg2 == PR_SET_PTRACER_ANY \|\| (int)arg2 == -1) {
bf06189e	150	rc = yama_ptracer_add(NULL, myself);
2d514487 KC	151	} else {
	152	struct task_struct *tracer;
	153
	154	rcu_read_lock();
	155	tracer = find_task_by_vpid(arg2);
	156	if (tracer)
	157	get_task_struct(tracer);
	158	else
	159	rc = -EINVAL;
	160	rcu_read_unlock();
	161
	162	if (tracer) {
	163	rc = yama_ptracer_add(tracer, myself);
	164	put_task_struct(tracer);
	165	}
	166	}
	167
	168	put_task_struct(myself);
	169	break;
	170	}
	171
	172	return rc;
	173	}
	174
	175	/**
	176	* task_is_descendant - walk up a process family tree looking for a match
	177	* @parent: the process to compare against while walking up from child
	178	* @child: the process to start from while looking upwards for parent
	179	*
	180	* Returns 1 if child is a descendant of parent, 0 if not.
	181	*/
	182	static int task_is_descendant(struct task_struct *parent,
	183	struct task_struct *child)
	184	{
	185	int rc = 0;
	186	struct task_struct *walker = child;
	187
	188	if (!parent \|\| !child)
	189	return 0;
	190
	191	rcu_read_lock();
	192	if (!thread_group_leader(parent))
	193	parent = rcu_dereference(parent->group_leader);
	194	while (walker->pid > 0) {
	195	if (!thread_group_leader(walker))
	196	walker = rcu_dereference(walker->group_leader);
	197	if (walker == parent) {
	198	rc = 1;
	199	break;
	200	}
	201	walker = rcu_dereference(walker->real_parent);
	202	}
	203	rcu_read_unlock();
	204
	205	return rc;
	206	}
	207
	208	/**
	209	* ptracer_exception_found - tracer registered as exception for this tracee
	210	* @tracer: the task_struct of the process attempting ptrace
	211	* @tracee: the task_struct of the process to be ptraced
	212	*
	213	* Returns 1 if tracer has is ptracer exception ancestor for tracee.
	214	*/
215	static int ptracer_exception_found(struct task_struct *tracer,
216	struct task_struct *tracee)
217	{
218	int rc = 0;
219	struct ptrace_relation *relation;
220	struct task_struct *parent = NULL;
bf06189e	221	bool found = false;
2d514487	222
2d514487 KC	223	rcu_read_lock();
	224	if (!thread_group_leader(tracee))
	225	tracee = rcu_dereference(tracee->group_leader);
93b69d43	226	list_for_each_entry_rcu(relation, &ptracer_relations, node)
2d514487 KC	227	if (relation->tracee == tracee) {
2d514487 KC	228	parent = relation->tracer;
bf06189e	229	found = true;
2d514487 KC	230	break;
	231	}
	232
bf06189e	233	if (found && (parent == NULL \|\| task_is_descendant(parent, tracer)))
2d514487 KC	234	rc = 1;
2d514487 KC	235	rcu_read_unlock();
2d514487 KC	236
	237	return rc;
	238	}
	239
	240	/**
	241	* yama_ptrace_access_check - validate PTRACE_ATTACH calls
	242	* @child: task that current task is attempting to ptrace
	243	* @mode: ptrace attach mode
	244	*
	245	* Returns 0 if following the ptrace is allowed, -ve on error.
	246	*/
c6993e4a	247	int yama_ptrace_access_check(struct task_struct *child,
2d514487 KC	248	unsigned int mode)
	249	{
	250	int rc;
	251
	252	/* If standard caps disallows it, so does Yama. We should
	253	* only tighten restrictions further.
	254	*/
	255	rc = cap_ptrace_access_check(child, mode);
	256	if (rc)
	257	return rc;
	258
	259	/* require ptrace target be a child of ptracer on attach */
389da25f KC	260	if (mode == PTRACE_MODE_ATTACH) {
	261	switch (ptrace_scope) {
	262	case YAMA_SCOPE_DISABLED:
	263	/* No additional restrictions. */
	264	break;
	265	case YAMA_SCOPE_RELATIONAL:
	266	if (!task_is_descendant(current, child) &&
	267	!ptracer_exception_found(current, child) &&
2cc8a716	268	!ns_capable(task_user_ns(child), CAP_SYS_PTRACE))
389da25f KC	269	rc = -EPERM;
	270	break;
	271	case YAMA_SCOPE_CAPABILITY:
2cc8a716	272	if (!ns_capable(task_user_ns(child), CAP_SYS_PTRACE))
389da25f KC	273	rc = -EPERM;
	274	break;
	275	case YAMA_SCOPE_NO_ATTACH:
	276	default:
	277	rc = -EPERM;
	278	break;
	279	}
	280	}
2d514487 KC	281
2d514487 KC	282	if (rc) {
389da25f KC	283	printk_ratelimited(KERN_NOTICE
389da25f KC	284	"ptrace of pid %d was attempted by: %s (pid %d)\n",
7612bfee	285	child->pid, current->comm, current->pid);
2d514487 KC	286	}
	287
	288	return rc;
	289	}
	290
9d8dad74 KC	291	/**
	292	* yama_ptrace_traceme - validate PTRACE_TRACEME calls
	293	* @parent: task that will become the ptracer of the current task
	294	*
	295	* Returns 0 if following the ptrace is allowed, -ve on error.
	296	*/
c6993e4a	297	int yama_ptrace_traceme(struct task_struct *parent)
9d8dad74 KC	298	{
	299	int rc;
	300
	301	/* If standard caps disallows it, so does Yama. We should
	302	* only tighten restrictions further.
	303	*/
	304	rc = cap_ptrace_traceme(parent);
	305	if (rc)
	306	return rc;
	307
	308	/* Only disallow PTRACE_TRACEME on more aggressive settings. */
	309	switch (ptrace_scope) {
	310	case YAMA_SCOPE_CAPABILITY:
	311	if (!ns_capable(task_user_ns(parent), CAP_SYS_PTRACE))
	312	rc = -EPERM;
	313	break;
	314	case YAMA_SCOPE_NO_ATTACH:
	315	rc = -EPERM;
	316	break;
	317	}
	318
	319	if (rc) {
9d8dad74 KC	320	printk_ratelimited(KERN_NOTICE
9d8dad74 KC	321	"ptraceme of pid %d was attempted by: %s (pid %d)\n",
7612bfee	322	current->pid, parent->comm, parent->pid);
9d8dad74 KC	323	}
	324
	325	return rc;
	326	}
	327
c6993e4a	328	#ifndef CONFIG_SECURITY_YAMA_STACKED
2d514487 KC	329	static struct security_operations yama_ops = {
	330	.name = "yama",
	331
	332	.ptrace_access_check = yama_ptrace_access_check,
9d8dad74	333	.ptrace_traceme = yama_ptrace_traceme,
2d514487 KC	334	.task_prctl = yama_task_prctl,
	335	.task_free = yama_task_free,
	336	};
c6993e4a	337	#endif
2d514487 KC	338
2d514487 KC	339	#ifdef CONFIG_SYSCTL
389da25f KC	340	static int yama_dointvec_minmax(struct ctl_table *table, int write,
	341	void __user buffer, size_t lenp, loff_t *ppos)
	342	{
	343	int rc;
	344
	345	if (write && !capable(CAP_SYS_PTRACE))
	346	return -EPERM;
	347
	348	rc = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
	349	if (rc)
	350	return rc;
	351
	352	/* Lock the max value if it ever gets set. */
	353	if (write && (int )table->data == (int )table->extra2)
	354	table->extra1 = table->extra2;
	355
	356	return rc;
	357	}
	358
2d514487	359	static int zero;
389da25f	360	static int max_scope = YAMA_SCOPE_NO_ATTACH;
2d514487 KC	361
	362	struct ctl_path yama_sysctl_path[] = {
	363	{ .procname = "kernel", },
	364	{ .procname = "yama", },
	365	{ }
	366	};
	367
	368	static struct ctl_table yama_sysctl_table[] = {
	369	{
	370	.procname = "ptrace_scope",
	371	.data = &ptrace_scope,
	372	.maxlen = sizeof(int),
	373	.mode = 0644,
389da25f	374	.proc_handler = yama_dointvec_minmax,
2d514487	375	.extra1 = &zero,
389da25f	376	.extra2 = &max_scope,
2d514487 KC	377	},
	378	{ }
	379	};
	380	#endif /* CONFIG_SYSCTL */
	381
	382	static __init int yama_init(void)
	383	{
c6993e4a	384	#ifndef CONFIG_SECURITY_YAMA_STACKED
2d514487 KC	385	if (!security_module_enable(&yama_ops))
2d514487 KC	386	return 0;
c6993e4a	387	#endif
2d514487 KC	388
	389	printk(KERN_INFO "Yama: becoming mindful.\n");
	390
c6993e4a	391	#ifndef CONFIG_SECURITY_YAMA_STACKED
2d514487 KC	392	if (register_security(&yama_ops))
2d514487 KC	393	panic("Yama: kernel registration failed.\n");
c6993e4a	394	#endif
2d514487 KC	395
	396	#ifdef CONFIG_SYSCTL
	397	if (!register_sysctl_paths(yama_sysctl_path, yama_sysctl_table))
	398	panic("Yama: sysctl registration failed.\n");
	399	#endif
	400
	401	return 0;
	402	}
	403
	404	security_initcall(yama_init);