This is xnu-8019. See this file in:
/*
 * Copyright (c) 2005-2016 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

/*
 * process policy syscall implementation
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/proc_internal.h>
#include <sys/proc.h>
#include <sys/kauth.h>
#include <sys/unistd.h>
#include <sys/buf.h>
#include <sys/ioctl.h>
#include <sys/vm.h>
#include <sys/user.h>

#include <mach/machine.h>
#include <mach/mach_types.h>
#include <mach/vm_param.h>
#include <kern/task.h>
#include <kern/assert.h>
#include <kern/policy_internal.h>

#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <mach/host_info.h>
#include <mach/task_info.h>
#include <mach/thread_info.h>
#include <mach/vm_region.h>

#include <sys/process_policy.h>
#include <sys/proc_info.h>
#include <sys/bsdtask_info.h>
#include <sys/kdebug.h>
#include <sys/sysproto.h>
#include <sys/msgbuf.h>

#include <machine/machine_routines.h>

#include <kern/ipc_misc.h>
#include <vm/vm_protos.h>

#if !defined(XNU_TARGET_OS_OSX)
#include <sys/kern_memorystatus.h>
#endif /* !defined(XNU_TARGET_OS_OSX) */

#if CONFIG_MACF
#include <security/mac.h>
#include <security/mac_framework.h>
#endif /* CONFIG_MACF */

static int handle_lowresource(int scope, int action, int policy, int policy_subtype, user_addr_t attrp, proc_t proc, uint64_t target_threadid);
static int handle_cpuuse(int action, user_addr_t attrp, proc_t proc, uint64_t target_threadid);
static int handle_apptype(int scope, int action, int policy, int policy_subtype, user_addr_t attrp, proc_t proc, uint64_t target_threadid);
static int handle_boost(int scope, int action, int policy, int policy_subtype, user_addr_t attrp, proc_t proc, uint64_t target_threadid);
static int handle_no_smt(int scope, int action, proc_t target_proc, uint64_t target_threadid);
static int handle_tecs(int scope, int action, proc_t target_proc, uint64_t target_threadid);

extern kern_return_t task_suspend(task_t);
extern kern_return_t task_resume(task_t);

#if !defined(XNU_TARGET_OS_OSX)
static int handle_applifecycle(int scope, int action, int policy, int policy_subtype, user_addr_t attrp, proc_t proc, uint64_t target_threadid);
#endif /* !defined(XNU_TARGET_OS_OSX) */

/***************************** process_policy ********************/

/*
 * int process_policy(int scope, int action, int policy, int policy_subtype,
 *                   proc_policy_attribute_t * attrp, pid_t target_pid,
 *                   uint64_t target_threadid)
 *{ int process_policy(int scope, int action, int policy, int policy_subtype,
 * user_addr_t attrp, pid_t target_pid, uint64_t target_threadid); }
 */

/* system call implementation */
int
process_policy(__unused struct proc *p, struct process_policy_args * uap, __unused int32_t *retval)
{
	int error = 0;
	int scope = uap->scope;
	int policy = uap->policy;
	int action = uap->action;
	int policy_subtype = uap->policy_subtype;
	user_addr_t attrp = uap->attrp;
	pid_t target_pid = uap->target_pid;
	uint64_t target_threadid = uap->target_threadid;
	proc_t target_proc = PROC_NULL;
#if CONFIG_MACF || defined(XNU_TARGET_OS_OSX)
	proc_t curp = current_proc();
#endif
	kauth_cred_t my_cred;
#if !defined(XNU_TARGET_OS_OSX)
	kauth_cred_t target_cred;
#endif

	if ((scope != PROC_POLICY_SCOPE_PROCESS) && (scope != PROC_POLICY_SCOPE_THREAD)) {
		return EINVAL;
	}

	if (target_pid == 0 || target_pid == proc_selfpid()) {
		target_proc = proc_self();
	} else {
		target_proc = proc_find(target_pid);
	}

	if (target_proc == PROC_NULL) {
		return ESRCH;
	}

	my_cred = kauth_cred_get();

#if !defined(XNU_TARGET_OS_OSX)
	target_cred = kauth_cred_proc_ref(target_proc);

	if (!kauth_cred_issuser(my_cred) && kauth_cred_getruid(my_cred) &&
	    kauth_cred_getuid(my_cred) != kauth_cred_getuid(target_cred) &&
	    kauth_cred_getruid(my_cred) != kauth_cred_getuid(target_cred))
#else
	/*
	 * Resoure starvation control can be used by unpriv resource owner but priv at the time of ownership claim. This is
	 * checked in low resource handle routine. So bypass the checks here.
	 */
	if ((policy != PROC_POLICY_RESOURCE_STARVATION) &&
	    (policy != PROC_POLICY_APPTYPE) &&
	    (!kauth_cred_issuser(my_cred) && curp != target_proc))
#endif
	{
		error = EPERM;
		goto out;
	}

#if CONFIG_MACF
	switch (policy) {
	case PROC_POLICY_BOOST:
	case PROC_POLICY_RESOURCE_USAGE:
#if !defined(XNU_TARGET_OS_OSX)
	case PROC_POLICY_APPTYPE:
	case PROC_POLICY_APP_LIFECYCLE:
#endif
		/* These policies do their own appropriate mac checks */
		break;
	default:
		error = mac_proc_check_sched(curp, target_proc);
		if (error) {
			goto out;
		}
		break;
	}
#endif /* CONFIG_MACF */

	switch (policy) {
	case PROC_POLICY_BACKGROUND:
		error = ENOTSUP;
		break;
	case PROC_POLICY_HARDWARE_ACCESS:
		error = ENOTSUP;
		break;
	case PROC_POLICY_RESOURCE_STARVATION:
		error = handle_lowresource(scope, action, policy, policy_subtype, attrp, target_proc, target_threadid);
		break;
	case PROC_POLICY_RESOURCE_USAGE:
		switch (policy_subtype) {
		case PROC_POLICY_RUSAGE_NONE:
		case PROC_POLICY_RUSAGE_WIREDMEM:
		case PROC_POLICY_RUSAGE_VIRTMEM:
		case PROC_POLICY_RUSAGE_DISK:
		case PROC_POLICY_RUSAGE_NETWORK:
		case PROC_POLICY_RUSAGE_POWER:
			error = ENOTSUP;
			goto out;
		default:
			error = EINVAL;
			goto out;
		case PROC_POLICY_RUSAGE_CPU:
			break;
		}

		error = handle_cpuuse(action, attrp, target_proc, target_threadid);
		break;
#if !defined(XNU_TARGET_OS_OSX)
	case PROC_POLICY_APP_LIFECYCLE:
		error = handle_applifecycle(scope, action, policy, policy_subtype, attrp, target_proc, target_threadid);
		break;
#endif /* !defined(XNU_TARGET_OS_OSX) */
	case PROC_POLICY_APPTYPE:
		error = handle_apptype(scope, action, policy, policy_subtype, attrp, target_proc, target_threadid);
		break;
	case PROC_POLICY_BOOST:
		error = handle_boost(scope, action, policy, policy_subtype, attrp, target_proc, target_threadid);
		break;
	case PROC_POLICY_NO_SMT:
		error = handle_no_smt(scope, action, target_proc, target_threadid);
		break;
	case PROC_POLICY_TECS:
		error = handle_tecs(scope, action, target_proc, target_threadid);
		break;
	default:
		error = EINVAL;
		break;
	}

out:
	proc_rele(target_proc);
#if !defined(XNU_TARGET_OS_OSX)
	kauth_cred_unref(&target_cred);
#endif
	return error;
}

static int
handle_lowresource(__unused int scope, int action, __unused int policy, int policy_subtype, __unused user_addr_t attrp, proc_t proc, __unused uint64_t target_threadid)
{
	int error = 0;

	switch (policy_subtype) {
	case PROC_POLICY_RS_NONE:
	case PROC_POLICY_RS_VIRTUALMEM:
		break;
	default:
		return EINVAL;
	}

	if (action == PROC_POLICY_ACTION_RESTORE) {
		error = proc_resetpcontrol(proc_pid(proc));
	} else {
		error = EINVAL;
	}

	return error;
}


static int
handle_cpuuse(int action, user_addr_t attrp, proc_t proc, __unused uint64_t target_threadid)
{
	proc_policy_cpuusage_attr_t     cpuattr = { };
#if CONFIG_MACF || defined(XNU_TARGET_OS_OSX)
	proc_t                          curp = current_proc();
#endif
	Boolean                         privileged = FALSE;
	Boolean                         canEnable = FALSE;
	uint64_t                        interval = -1ULL;
	int                             error = 0;
	uint8_t                         percentage;

#if defined(XNU_TARGET_OS_OSX)
	/* On macOS, tasks can only set and clear their own CPU limits. */
	if ((action == PROC_POLICY_ACTION_APPLY || action == PROC_POLICY_ACTION_RESTORE)
	    && curp != proc) {
		return EPERM;
	}
	/* No privilege required on macOS. */
	privileged = TRUE;
#endif

#if CONFIG_MACF
	/* Is caller privileged to set less-restrictive scheduling parameters? */
	if (!privileged) {
		privileged = (priv_check_cred(kauth_cred_get(), PRIV_PROC_CPUMON_OVERRIDE, 0) == 0);
	}
	canEnable = (privileged && action == PROC_POLICY_ACTION_ENABLE);

	if (!canEnable && curp != proc) {
		/*
		 * Can the current process change scheduling parameters for
		 * the target process?
		 */
		error = mac_proc_check_sched(curp, proc);
		if (error) {
			return error;
		}
	}
#endif

	switch (action) {
	case PROC_POLICY_ACTION_GET:
		error = proc_get_task_ruse_cpu(proc->task, &cpuattr.ppattr_cpu_attr,
		    &percentage,
		    &cpuattr.ppattr_cpu_attr_interval,
		    &cpuattr.ppattr_cpu_attr_deadline);
		if (error == 0) {
			cpuattr.ppattr_cpu_percentage = percentage;
			cpuattr.ppattr_cpu_attr_interval /= NSEC_PER_SEC;
			error = copyout((proc_policy_cpuusage_attr_t *)&cpuattr, (user_addr_t)attrp, sizeof(proc_policy_cpuusage_attr_t));
		}
		break;

	case PROC_POLICY_ACTION_APPLY:
	case PROC_POLICY_ACTION_SET:
		error = copyin((user_addr_t)attrp, (proc_policy_cpuusage_attr_t *)&cpuattr, sizeof(proc_policy_cpuusage_attr_t));
		if (error != 0) {
			return error;
		}

		/*
		 * The process_policy API uses seconds as the units for the interval,
		 * but the mach task policy SPI uses nanoseconds. Do the conversion,
		 * but preserve -1 as it has special meaning.
		 */
		if (cpuattr.ppattr_cpu_attr_interval != -1ULL) {
			interval = cpuattr.ppattr_cpu_attr_interval * NSEC_PER_SEC;
		} else {
			interval = -1ULL;
		}

		error = proc_set_task_ruse_cpu(proc->task, (uint16_t)cpuattr.ppattr_cpu_attr,
		    (uint8_t)MIN(cpuattr.ppattr_cpu_percentage, UINT8_MAX),
		    interval,
		    cpuattr.ppattr_cpu_attr_deadline,
		    privileged);
		break;

	/* restore process to prior state */
	case PROC_POLICY_ACTION_RESTORE:
		error = proc_clear_task_ruse_cpu(proc->task, privileged);
		break;

	/* re-enable suspended monitor */
	case PROC_POLICY_ACTION_ENABLE:
		error = task_resume_cpumon(proc->task);
		break;

	case PROC_POLICY_ACTION_REMOVE:

	default:
		error = EINVAL;
		break;
	}

	return error;
}

#if !defined(XNU_TARGET_OS_OSX)
static int
handle_applifecycle(__unused int scope,
    int action,
    __unused int policy,
    int policy_subtype,
    user_addr_t attrp,
    proc_t proc,
    __unused uint64_t target_threadid)
{
	int error = 0;
	int state = 0;

	switch (policy_subtype) {
	case PROC_POLICY_APPLIFE_NONE:
		error = 0;
		break;

	case PROC_POLICY_APPLIFE_STATE:
		/* appstate is no longer supported */
		error = ENOTSUP;
		break;

	case PROC_POLICY_APPLIFE_DEVSTATUS:
#if CONFIG_MACF
		/* ToDo - this should be a generic check, since we could potentially hang other behaviours here. */
		error = mac_proc_check_suspend_resume(proc, MAC_PROC_CHECK_HIBERNATE);
		if (error) {
			error = EPERM;
			goto out;
		}
#endif
#if CONFIG_MEMORYSTATUS
		if (action == PROC_POLICY_ACTION_APPLY) {
			/* Used as a freeze hint */
			memorystatus_on_inactivity(proc);

			/* in future use devicestatus for pid_socketshutdown() */
			error = 0;
		} else
#endif
		{
			error = EINVAL;
		}
		break;

	case PROC_POLICY_APPLIFE_PIDBIND:
#if CONFIG_MACF
		error = mac_proc_check_suspend_resume(proc, MAC_PROC_CHECK_PIDBIND);
		if (error) {
			error = EPERM;
			goto out;
		}
#endif
		error = copyin((user_addr_t)attrp, (int  *)&state, sizeof(int));
		if (error != 0) {
			goto out;
		}
#if CONFIG_TASKWATCH
		if (action == PROC_POLICY_ACTION_APPLY) {
			/* bind the thread in target_thread in current process to target_proc */
			error = proc_lf_pidbind(current_task(), target_threadid, proc->task, state);
		} else
#endif /* CONFIG_TASKWATCH */
		{
			error = EINVAL;
		}
		break;
	default:
		error = EINVAL;
		break;
	}

out:
	return error;
}
#endif /* !defined(XNU_TARGET_OS_OSX) */

static int
handle_apptype(         int scope,
    int action,
    __unused int policy,
    int policy_subtype,
    __unused user_addr_t attrp,
    proc_t target_proc,
    __unused uint64_t target_threadid)
{
	int error = 0;

	if (scope != PROC_POLICY_SCOPE_PROCESS) {
		return EINVAL;
	}

	/* Temporary compatibility with old importance donation interface until libproc is moved to new boost calls */
	switch (policy_subtype) {
	case PROC_POLICY_IOS_DONATEIMP:
		if (action != PROC_POLICY_ACTION_ENABLE) {
			return EINVAL;
		}
		if (target_proc != current_proc()) {
			return EINVAL;
		}

		/* PROCESS ENABLE APPTYPE DONATEIMP */
		task_importance_mark_donor(target_proc->task, TRUE);

		return 0;

	case PROC_POLICY_IOS_HOLDIMP:
		if (action != PROC_POLICY_ACTION_ENABLE) {
			return EINVAL;
		}
		if (target_proc != current_proc()) {
			return EINVAL;
		}

		/* PROCESS ENABLE APPTYPE HOLDIMP */
		error = task_importance_hold_legacy_external_assertion(current_task(), 1);

		return error;

	case PROC_POLICY_IOS_DROPIMP:
		if (action != PROC_POLICY_ACTION_ENABLE) {
			return EINVAL;
		}
		if (target_proc != current_proc()) {
			return EINVAL;
		}

		/* PROCESS ENABLE APPTYPE DROPIMP */
		error = task_importance_drop_legacy_external_assertion(current_task(), 1);

		return error;

	default:
		return EINVAL;
	}
}

static int
handle_boost(int scope,
    int action,
    __unused int policy,
    int policy_subtype,
    __unused user_addr_t attrp,
    proc_t target_proc,
    __unused uint64_t target_threadid)
{
	int error = 0;

	assert(policy == PROC_POLICY_BOOST);

	if (scope != PROC_POLICY_SCOPE_PROCESS) {
		return EINVAL;
	}

	if (target_proc != current_proc()) {
		return EINVAL;
	}

	switch (policy_subtype) {
	case PROC_POLICY_IMP_IMPORTANT:
		if (task_is_importance_receiver_type(target_proc->task) == FALSE) {
			return EINVAL;
		}

		switch (action) {
		case PROC_POLICY_ACTION_HOLD:
			/* PROCESS HOLD BOOST IMPORTANT */
			error = task_importance_hold_legacy_external_assertion(current_task(), 1);
			break;
		case PROC_POLICY_ACTION_DROP:
			/* PROCESS DROP BOOST IMPORTANT */
			error = task_importance_drop_legacy_external_assertion(current_task(), 1);
			break;
		default:
			error = (EINVAL);
			break;
		}
		break;

	case PROC_POLICY_IMP_DONATION:
#if CONFIG_MACF
		error = mac_proc_check_sched(current_proc(), target_proc);
		if (error) {
			return error;
		}
#endif
		switch (action) {
		case PROC_POLICY_ACTION_SET:
			/* PROCESS SET BOOST DONATION */
			task_importance_mark_donor(target_proc->task, TRUE);
			break;
		default:
			error = (EINVAL);
			break;
		}
		break;

	default:
		error = (EINVAL);
		break;
	}

	return error;
}

static int
handle_no_smt(int scope, int action, proc_t target_proc, uint64_t target_threadid)
{
	extern void task_set_no_smt(task_t);

	if (action != PROC_POLICY_ACTION_APPLY) {
		return EINVAL;
	}

	if (scope == PROC_POLICY_SCOPE_PROCESS) {
		if (target_proc != current_proc()) {
			return EINVAL;
		}
		task_set_no_smt(TASK_NULL);
	} else if (scope == PROC_POLICY_SCOPE_THREAD) {
		if (target_threadid != thread_tid(current_thread())) {
			return EINVAL;
		}
		thread_set_no_smt(true);
	} else {
		return EINVAL;
	}

	return 0;
}

static int
handle_tecs(int scope, int action, proc_t target_proc, uint64_t target_threadid)
{
	if (action != PROC_POLICY_ACTION_APPLY) {
		return EINVAL;
	}

	if (scope == PROC_POLICY_SCOPE_PROCESS) {
		if (target_proc != current_proc()) {
			return EINVAL;
		}
		task_set_tecs(TASK_NULL);
	} else if (scope == PROC_POLICY_SCOPE_THREAD) {
		if (target_threadid != thread_tid(current_thread())) {
			return EINVAL;
		}
		if (machine_csv(CPUVN_CI)) {
			machine_tecs(current_thread());
		}
	} else {
		return EINVAL;
	}

	return 0;
}

/*
 * KPI to determine if a pid is currently backgrounded.
 * Returns ESRCH if pid cannot be found or has started exiting.
 * Returns EINVAL if state is NULL.
 * Sets *state to 1 if pid is backgrounded, and 0 otherwise.
 */
int
proc_pidbackgrounded(pid_t pid, uint32_t* state)
{
	proc_t target_proc = PROC_NULL;

	if (state == NULL) {
		return EINVAL;
	}

	target_proc = proc_find(pid);

	if (target_proc == PROC_NULL) {
		return ESRCH;
	}

	if (proc_get_effective_task_policy(target_proc->task, TASK_POLICY_DARWIN_BG)) {
		*state = 1;
	} else {
		*state = 0;
	}

	proc_rele(target_proc);
	return 0;
}

/*
 * Get the darwin background state of the originator. If the current
 * process app type is App, then it is the originator, else if it is
 * a Daemon, then creator of the Resource Accounting attribute of
 * the current thread voucher is the originator of the work.
 */
int
proc_get_originatorbgstate(uint32_t *is_backgrounded)
{
	uint32_t bgstate;
	proc_t p = current_proc();
	uint32_t flagsp = 0;
	kern_return_t kr;
	pid_t pid;
	int ret;
	thread_t thread = current_thread();

	bgstate = proc_get_effective_thread_policy(thread, TASK_POLICY_DARWIN_BG);

	/* If current thread or task backgrounded, return background */
	if (bgstate) {
		*is_backgrounded = 1;
		return 0;
	}

	/* Check if current process app type is App, then return foreground */
	proc_get_darwinbgstate(p->task, &flagsp);
	if ((flagsp & PROC_FLAG_APPLICATION) == PROC_FLAG_APPLICATION) {
		*is_backgrounded = 0;
		return 0;
	}

	/*
	 * Get the current voucher origin pid and it's bgstate.The pid
	 * returned here might not be valid or may have been recycled.
	 */
	kr = thread_get_current_voucher_origin_pid(&pid);
	if (kr != KERN_SUCCESS) {
		if (kr == KERN_INVALID_TASK) {
			return ESRCH;
		} else if (kr == KERN_INVALID_VALUE) {
			return ENOATTR;
		} else {
			return EINVAL;
		}
	}

	ret = proc_pidbackgrounded(pid, is_backgrounded);
	return ret;
}

int
proc_apply_resource_actions(void * bsdinfo, __unused int type, int action)
{
	proc_t p = (proc_t)bsdinfo;

	switch (action) {
	case PROC_POLICY_RSRCACT_THROTTLE:
		/* no need to do anything */
		break;

	case PROC_POLICY_RSRCACT_SUSPEND:
		task_suspend(p->task);
		break;

	case PROC_POLICY_RSRCACT_TERMINATE:
		psignal(p, SIGKILL);
		break;

	case PROC_POLICY_RSRCACT_NOTIFY_KQ:
		/* not implemented */
		break;

	case PROC_POLICY_RSRCACT_NOTIFY_EXC:
		panic("shouldn't be applying exception notification to process!");
		break;
	}

	return 0;
}

int
proc_restore_resource_actions(void * bsdinfo, __unused int type, int action)
{
	proc_t p = (proc_t)bsdinfo;

	switch (action) {
	case PROC_POLICY_RSRCACT_THROTTLE:
	case PROC_POLICY_RSRCACT_TERMINATE:
	case PROC_POLICY_RSRCACT_NOTIFY_KQ:
	case PROC_POLICY_RSRCACT_NOTIFY_EXC:
		/* no need to do anything */
		break;

	case PROC_POLICY_RSRCACT_SUSPEND:
		task_resume(p->task);
		break;
	}

	return 0;
}