This is xnu-8019. See this file in:
/*
 * Copyright (c) 2000-2010 Apple 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@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*-
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)kern_acct.c	8.1 (Berkeley) 6/14/93
 */
/* HISTORY
 * 08-May-95  Mac Gillon (mgillon) at NeXT
 *	Purged old history
 *      New version based on 4.4
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */


#include <sys/param.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/mount_internal.h>
#include <sys/vnode_internal.h>
#include <sys/file_internal.h>
#include <sys/syslog.h>
#include <sys/kernel.h>
#include <sys/namei.h>
#include <sys/errno.h>
#include <sys/acct.h>
#include <sys/resourcevar.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/sysproto.h>
#if CONFIG_MACF
#include <security/mac_framework.h>
#endif

/*
 * The routines implemented in this file are described in:
 *      Leffler, et al.: The Design and Implementation of the 4.3BSD
 *	    UNIX Operating System (Addison Welley, 1989)
 * on pages 62-63.
 *
 * Arguably, to simplify accounting operations, this mechanism should
 * be replaced by one in which an accounting log file (similar to /dev/klog)
 * is read by a user process, etc.  However, that has its own problems.
 */

/*
 * Internal accounting functions.
 * The former's operation is described in Leffler, et al., and the latter
 * was provided by UCB with the 4.4BSD-Lite release
 */
comp_t  encode_comp_t(uint32_t, uint32_t);
void    acctwatch(void *);

/*
 * Accounting vnode pointer, and suspended accounting vnode pointer.  States
 * are as follows:
 *
 *	acctp		suspend_acctp	state
 *	-------------	------------	------------------------------
 *	NULL		NULL		Accounting disabled
 *	!NULL		NULL		Accounting enabled
 *	NULL		!NULL		Accounting enabled, but suspended
 *	!NULL		!NULL		<not allowed>
 */
struct  vnode *acctp;
struct  vnode *suspend_acctp;

/*
 * Values associated with enabling and disabling accounting
 */
int     acctsuspend = 2;        /* stop accounting when < 2% free space left */
int     acctresume = 4;         /* resume when free space risen to > 4% */
int     acctchkfreq = 15;       /* frequency (in seconds) to check space */


static LCK_GRP_DECLARE(acct_subsys_lck_grp, "acct");
static LCK_MTX_DECLARE(acct_subsys_mutex, &acct_subsys_lck_grp);

#define ACCT_SUBSYS_LOCK() lck_mtx_lock(&acct_subsys_mutex)
#define ACCT_SUBSYS_UNLOCK() lck_mtx_unlock(&acct_subsys_mutex)


/*
 * Accounting system call.  Written based on the specification and
 * previous implementation done by Mark Tinguely.
 */
int
acct(proc_t p, struct acct_args *uap, __unused int *retval)
{
	struct nameidata nd;
	int error;
	struct vfs_context *ctx;

	ctx = vfs_context_current();

	/* Make sure that the caller is root. */
	if ((error = suser(vfs_context_ucred(ctx), &p->p_acflag))) {
		return error;
	}

	/*
	 * If accounting is to be started to a file, open that file for
	 * writing and make sure it's a 'normal'.
	 */
	if (uap->path != USER_ADDR_NULL) {
		NDINIT(&nd, LOOKUP, OP_OPEN, NOFOLLOW, UIO_USERSPACE, uap->path, ctx);
		if ((error = vn_open(&nd, FWRITE, 0))) {
			return error;
		}
#if CONFIG_MACF
		error = mac_system_check_acct(vfs_context_ucred(ctx), nd.ni_vp);
		if (error) {
			vnode_put(nd.ni_vp);
			vn_close(nd.ni_vp, FWRITE, ctx);
			return error;
		}
#endif
		vnode_put(nd.ni_vp);

		if (nd.ni_vp->v_type != VREG) {
			vn_close(nd.ni_vp, FWRITE, ctx);
			return EACCES;
		}
	}
#if CONFIG_MACF
	else {
		error = mac_system_check_acct(vfs_context_ucred(ctx), NULL);
		if (error) {
			return error;
		}
	}
#endif

	/*
	 * If accounting was previously enabled, kill the old space-watcher,
	 * close the file, and (if no new file was specified, leave).
	 */
	ACCT_SUBSYS_LOCK();
	if (acctp != NULLVP || suspend_acctp != NULLVP) {
		untimeout(acctwatch, NULL);
		error = vn_close((acctp != NULLVP ? acctp : suspend_acctp),
		    FWRITE, vfs_context_current());

		acctp = suspend_acctp = NULLVP;
	}
	if (uap->path == USER_ADDR_NULL) {
		ACCT_SUBSYS_UNLOCK();
		return error;
	}

	/*
	 * Save the new accounting file vnode, and schedule the new
	 * free space watcher.
	 */
	acctp = nd.ni_vp;
	ACCT_SUBSYS_UNLOCK();

	acctwatch(NULL);
	return error;
}

/*
 * Write out process accounting information, on process exit.
 * Data to be written out is specified in Leffler, et al.
 * and are enumerated below.  (They're also noted in the system
 * "acct.h" header file.)
 */
int
acct_process(proc_t p)
{
	struct acct an_acct;
	struct rusage rup, *r;
	struct timeval ut, st, tmp;
	int t;
	int error;
	struct vnode *vp;
	kauth_cred_t safecred;
	struct pgrp *pg;

	/* If accounting isn't enabled, don't bother */
	ACCT_SUBSYS_LOCK();
	vp = acctp;
	if (vp == NULLVP) {
		ACCT_SUBSYS_UNLOCK();
		return 0;
	}

	/*
	 * Get process accounting information.
	 */

	/* (1) The name of the command that ran */
	bcopy(p->p_comm, an_acct.ac_comm, sizeof an_acct.ac_comm);

	/* (2) The amount of user and system time that was used */
	calcru(p, &ut, &st, NULL);
	an_acct.ac_utime = encode_comp_t((uint32_t)ut.tv_sec, ut.tv_usec);
	an_acct.ac_stime = encode_comp_t((uint32_t)st.tv_sec, st.tv_usec);

	/* (3) The elapsed time the commmand ran (and its starting time) */
	an_acct.ac_btime = (u_int32_t)p->p_start.tv_sec;
	microtime(&tmp);
	timevalsub(&tmp, &p->p_start);
	an_acct.ac_etime = encode_comp_t((uint32_t)tmp.tv_sec, tmp.tv_usec);

	/* (4) The average amount of memory used */
	proc_lock(p);
	rup = p->p_stats->p_ru;
	proc_unlock(p);
	r = &rup;
	tmp = ut;
	timevaladd(&tmp, &st);
	t = (int)(tmp.tv_sec * hz + tmp.tv_usec / tick);
	if (t) {
		an_acct.ac_mem = (u_int16_t)((r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t);
	} else {
		an_acct.ac_mem = 0;
	}

	/* (5) The number of disk I/O operations done */
	an_acct.ac_io = encode_comp_t((uint32_t)(r->ru_inblock + r->ru_oublock), 0);

	/* (6) The UID and GID of the process */
	safecred = kauth_cred_proc_ref(p);

	an_acct.ac_uid = kauth_cred_getruid(safecred);
	an_acct.ac_gid = kauth_cred_getrgid(safecred);

	/* (7) The terminal from which the process was started */

	an_acct.ac_tty = NODEV;
	if ((p->p_flag & P_CONTROLT) && (pg = proc_pgrp(p, NULL))) {
		an_acct.ac_tty = os_atomic_load(&pg->pg_session->s_ttydev, relaxed);
		pgrp_rele(pg);
	}

	/* (8) The boolean flags that tell how the process terminated, etc. */
	an_acct.ac_flag = (u_int8_t)p->p_acflag;

	/*
	 * Now, just write the accounting information to the file.
	 */
	if ((error = vnode_getwithref(vp)) == 0) {
		error = vn_rdwr(UIO_WRITE, vp, (caddr_t)&an_acct, sizeof(an_acct),
		    (off_t)0, UIO_SYSSPACE, IO_APPEND | IO_UNIT, safecred,
		    (int *)0, p);
		vnode_put(vp);
	}

	kauth_cred_unref(&safecred);
	ACCT_SUBSYS_UNLOCK();

	return error;
}

/*
 * Encode_comp_t converts from ticks in seconds and microseconds
 * to ticks in 1/AHZ seconds.  The encoding is described in
 * Leffler, et al., on page 63.
 */

#define MANTSIZE        13                      /* 13 bit mantissa. */
#define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
#define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */

comp_t
encode_comp_t(uint32_t s, uint32_t us)
{
	int exp, rnd;

	exp = 0;
	rnd = 0;
	s *= AHZ;
	s += us / (1000000 / AHZ);      /* Maximize precision. */

	while (s > MAXFRACT) {
		rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
		s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
		exp++;
	}

	/* If we need to round up, do it (and handle overflow correctly). */
	if (rnd && (++s > MAXFRACT)) {
		s >>= EXPSIZE;
		exp++;
	}

	/* Clean it up and polish it off. */
	exp <<= MANTSIZE;               /* Shift the exponent into place */
	exp += s;                       /* and add on the mantissa. */
	return (comp_t)exp;
}

/*
 * Periodically check the file system to see if accounting
 * should be turned on or off.  Beware the case where the vnode
 * has been vgone()'d out from underneath us, e.g. when the file
 * system containing the accounting file has been forcibly unmounted.
 */
/* ARGSUSED */
void
acctwatch(__unused void *a)
{
	vfs_context_t ctx = vfs_context_current();
	struct vfs_attr va;

	VFSATTR_INIT(&va);
	VFSATTR_WANTED(&va, f_blocks);
	VFSATTR_WANTED(&va, f_bavail);

	ACCT_SUBSYS_LOCK();
	if (suspend_acctp != NULLVP) {
		/*
		 * Resuming accounting when accounting is suspended, and the
		 * filesystem containing the suspended accounting file goes
		 * below a low watermark
		 */
		if (suspend_acctp->v_type == VBAD) {
			(void) vn_close(suspend_acctp, FWRITE, vfs_context_kernel());
			suspend_acctp = NULLVP;
			ACCT_SUBSYS_UNLOCK();
			return;
		}
		(void)vfs_getattr(suspend_acctp->v_mount, &va, ctx);
		if (va.f_bavail > acctresume * va.f_blocks / 100) {
			acctp = suspend_acctp;
			suspend_acctp = NULLVP;
			log(LOG_NOTICE, "Accounting resumed\n");
		}
	} else if (acctp != NULLVP) {
		/*
		 * Suspending accounting when accounting is currently active,
		 * and the filesystem containing the active accounting file
		 * goes over a high watermark
		 */
		if (acctp->v_type == VBAD) {
			(void) vn_close(acctp, FWRITE, vfs_context_kernel());
			acctp = NULLVP;
			ACCT_SUBSYS_UNLOCK();
			return;
		}
		(void)vfs_getattr(acctp->v_mount, &va, ctx);
		if (va.f_bavail <= acctsuspend * va.f_blocks / 100) {
			suspend_acctp = acctp;
			acctp = NULLVP;
			log(LOG_NOTICE, "Accounting suspended\n");
		}
	} else {
		ACCT_SUBSYS_UNLOCK();
		return;
	}
	ACCT_SUBSYS_UNLOCK();

	timeout(acctwatch, NULL, acctchkfreq * hz);
}