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| Current File : //sys/kern/kern_acct.c |
/*-
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* Copyright (c) 2005 Robert N. M. Watson
* All rights reserved.
*
* 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.
* 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.
*
* Copyright (c) 1994 Christopher G. Demetriou
*
* 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
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/kern_acct.c 225617 2011-09-16 13:58:51Z kmacy $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/acct.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/syslog.h>
#include <sys/sysproto.h>
#include <sys/tty.h>
#include <sys/vnode.h>
#include <security/mac/mac_framework.h>
/*
* 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.
* On May 2007 the historic 3 bits base 8 exponent, 13 bit fraction
* compt_t representation described in the above reference was replaced
* with that of IEEE-754 floats.
*
* 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.
*/
/* Floating point definitions from <float.h>. */
#define FLT_MANT_DIG 24 /* p */
#define FLT_MAX_EXP 128 /* emax */
/*
* 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
*/
static uint32_t encode_timeval(struct timeval);
static uint32_t encode_long(long);
static void acctwatch(void);
static void acct_thread(void *);
static int acct_disable(struct thread *);
/*
* Accounting vnode pointer, saved vnode pointer, and flags for each.
* acct_sx protects against changes to the active vnode and credentials
* while accounting records are being committed to disk.
*/
static int acct_configured;
static int acct_suspended;
static struct vnode *acct_vp;
static struct ucred *acct_cred;
static int acct_flags;
static struct sx acct_sx;
SX_SYSINIT(acct, &acct_sx, "acct_sx");
/*
* State of the accounting kthread.
*/
static int acct_state;
#define ACCT_RUNNING 1 /* Accounting kthread is running. */
#define ACCT_EXITREQ 2 /* Accounting kthread should exit. */
/*
* Values associated with enabling and disabling accounting
*/
static int acctsuspend = 2; /* stop accounting when < 2% free space left */
SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
&acctsuspend, 0, "percentage of free disk space below which accounting stops");
static int acctresume = 4; /* resume when free space risen to > 4% */
SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
&acctresume, 0, "percentage of free disk space above which accounting resumes");
static int acctchkfreq = 15; /* frequency (in seconds) to check space */
static int
sysctl_acct_chkfreq(SYSCTL_HANDLER_ARGS)
{
int error, value;
/* Write out the old value. */
error = SYSCTL_OUT(req, &acctchkfreq, sizeof(int));
if (error || req->newptr == NULL)
return (error);
/* Read in and verify the new value. */
error = SYSCTL_IN(req, &value, sizeof(int));
if (error)
return (error);
if (value <= 0)
return (EINVAL);
acctchkfreq = value;
return (0);
}
SYSCTL_PROC(_kern, OID_AUTO, acct_chkfreq, CTLTYPE_INT|CTLFLAG_RW,
&acctchkfreq, 0, sysctl_acct_chkfreq, "I",
"frequency for checking the free space");
SYSCTL_INT(_kern, OID_AUTO, acct_configured, CTLFLAG_RD, &acct_configured, 0,
"Accounting configured or not");
SYSCTL_INT(_kern, OID_AUTO, acct_suspended, CTLFLAG_RD, &acct_suspended, 0,
"Accounting suspended or not");
/*
* Accounting system call. Written based on the specification and previous
* implementation done by Mark Tinguely.
*/
int
sys_acct(struct thread *td, struct acct_args *uap)
{
struct nameidata nd;
int error, flags, vfslocked;
error = priv_check(td, PRIV_ACCT);
if (error)
return (error);
/*
* If accounting is to be started to a file, open that file for
* appending and make sure it's a 'normal'.
*/
if (uap->path != NULL) {
NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE | AUDITVNODE1,
UIO_USERSPACE, uap->path, td);
flags = FWRITE | O_APPEND;
error = vn_open(&nd, &flags, 0, NULL);
if (error)
return (error);
vfslocked = NDHASGIANT(&nd);
NDFREE(&nd, NDF_ONLY_PNBUF);
#ifdef MAC
error = mac_system_check_acct(td->td_ucred, nd.ni_vp);
if (error) {
VOP_UNLOCK(nd.ni_vp, 0);
vn_close(nd.ni_vp, flags, td->td_ucred, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
#endif
VOP_UNLOCK(nd.ni_vp, 0);
if (nd.ni_vp->v_type != VREG) {
vn_close(nd.ni_vp, flags, td->td_ucred, td);
VFS_UNLOCK_GIANT(vfslocked);
return (EACCES);
}
VFS_UNLOCK_GIANT(vfslocked);
#ifdef MAC
} else {
error = mac_system_check_acct(td->td_ucred, NULL);
if (error)
return (error);
#endif
}
/*
* Disallow concurrent access to the accounting vnode while we swap
* it out, in order to prevent access after close.
*/
sx_xlock(&acct_sx);
/*
* If accounting was previously enabled, kill the old space-watcher,
* close the file, and (if no new file was specified, leave). Reset
* the suspended state regardless of whether accounting remains
* enabled.
*/
acct_suspended = 0;
if (acct_vp != NULL) {
vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
error = acct_disable(td);
VFS_UNLOCK_GIANT(vfslocked);
}
if (uap->path == NULL) {
if (acct_state & ACCT_RUNNING) {
acct_state |= ACCT_EXITREQ;
wakeup(&acct_state);
}
sx_xunlock(&acct_sx);
return (error);
}
/*
* Save the new accounting file vnode, and schedule the new
* free space watcher.
*/
acct_vp = nd.ni_vp;
acct_cred = crhold(td->td_ucred);
acct_flags = flags;
if (acct_state & ACCT_RUNNING)
acct_state &= ~ACCT_EXITREQ;
else {
/*
* Try to start up an accounting kthread. We may start more
* than one, but if so the extras will commit suicide as
* soon as they start up.
*/
error = kproc_create(acct_thread, NULL, NULL, 0, 0,
"accounting");
if (error) {
vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
(void) vn_close(acct_vp, acct_flags, acct_cred, td);
VFS_UNLOCK_GIANT(vfslocked);
crfree(acct_cred);
acct_configured = 0;
acct_vp = NULL;
acct_cred = NULL;
acct_flags = 0;
sx_xunlock(&acct_sx);
log(LOG_NOTICE, "Unable to start accounting thread\n");
return (error);
}
}
acct_configured = 1;
sx_xunlock(&acct_sx);
log(LOG_NOTICE, "Accounting enabled\n");
return (error);
}
/*
* Disable currently in-progress accounting by closing the vnode, dropping
* our reference to the credential, and clearing the vnode's flags.
*/
static int
acct_disable(struct thread *td)
{
int error;
sx_assert(&acct_sx, SX_XLOCKED);
error = vn_close(acct_vp, acct_flags, acct_cred, td);
crfree(acct_cred);
acct_configured = 0;
acct_vp = NULL;
acct_cred = NULL;
acct_flags = 0;
log(LOG_NOTICE, "Accounting disabled\n");
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(struct thread *td)
{
struct acctv2 acct;
struct timeval ut, st, tmp;
struct plimit *newlim, *oldlim;
struct proc *p;
struct rusage ru;
int t, ret, vfslocked;
/*
* Lockless check of accounting condition before doing the hard
* work.
*/
if (acct_vp == NULL || acct_suspended)
return (0);
sx_slock(&acct_sx);
/*
* If accounting isn't enabled, don't bother. Have to check again
* once we own the lock in case we raced with disabling of accounting
* by another thread.
*/
if (acct_vp == NULL || acct_suspended) {
sx_sunlock(&acct_sx);
return (0);
}
p = td->td_proc;
/*
* Get process accounting information.
*/
sx_slock(&proctree_lock);
PROC_LOCK(p);
/* (1) The terminal from which the process was started */
if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
acct.ac_tty = tty_udev(p->p_pgrp->pg_session->s_ttyp);
else
acct.ac_tty = NODEV;
sx_sunlock(&proctree_lock);
/* (2) The name of the command that ran */
bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
/* (3) The amount of user and system time that was used */
rufetchcalc(p, &ru, &ut, &st);
acct.ac_utime = encode_timeval(ut);
acct.ac_stime = encode_timeval(st);
/* (4) The elapsed time the command ran (and its starting time) */
tmp = boottime;
timevaladd(&tmp, &p->p_stats->p_start);
acct.ac_btime = tmp.tv_sec;
microuptime(&tmp);
timevalsub(&tmp, &p->p_stats->p_start);
acct.ac_etime = encode_timeval(tmp);
/* (5) The average amount of memory used */
tmp = ut;
timevaladd(&tmp, &st);
/* Convert tmp (i.e. u + s) into hz units to match ru_i*. */
t = tmp.tv_sec * hz + tmp.tv_usec / tick;
if (t)
acct.ac_mem = encode_long((ru.ru_ixrss + ru.ru_idrss +
+ ru.ru_isrss) / t);
else
acct.ac_mem = 0;
/* (6) The number of disk I/O operations done */
acct.ac_io = encode_long(ru.ru_inblock + ru.ru_oublock);
/* (7) The UID and GID of the process */
acct.ac_uid = p->p_ucred->cr_ruid;
acct.ac_gid = p->p_ucred->cr_rgid;
/* (8) The boolean flags that tell how the process terminated, etc. */
acct.ac_flagx = p->p_acflag;
PROC_UNLOCK(p);
/* Setup ancillary structure fields. */
acct.ac_flagx |= ANVER;
acct.ac_zero = 0;
acct.ac_version = 2;
acct.ac_len = acct.ac_len2 = sizeof(acct);
/*
* Eliminate any file size rlimit.
*/
newlim = lim_alloc();
PROC_LOCK(p);
oldlim = p->p_limit;
lim_copy(newlim, oldlim);
newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
p->p_limit = newlim;
PROC_UNLOCK(p);
lim_free(oldlim);
/*
* Write the accounting information to the file.
*/
vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct),
(off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED,
NULL, td);
VFS_UNLOCK_GIANT(vfslocked);
sx_sunlock(&acct_sx);
return (ret);
}
/* FLOAT_CONVERSION_START (Regression testing; don't remove this line.) */
/* Convert timevals and longs into IEEE-754 bit patterns. */
/* Mantissa mask (MSB is implied, so subtract 1). */
#define MANT_MASK ((1 << (FLT_MANT_DIG - 1)) - 1)
/*
* We calculate integer values to a precision of approximately
* 28 bits.
* This is high-enough precision to fill the 24 float bits
* and low-enough to avoid overflowing the 32 int bits.
*/
#define CALC_BITS 28
/* log_2(1000000). */
#define LOG2_1M 20
/*
* Convert the elements of a timeval into a 32-bit word holding
* the bits of a IEEE-754 float.
* The float value represents the timeval's value in microsecond units.
*/
static uint32_t
encode_timeval(struct timeval tv)
{
int log2_s;
int val, exp; /* Unnormalized value and exponent */
int norm_exp; /* Normalized exponent */
int shift;
/*
* First calculate value and exponent to about CALC_BITS precision.
* Note that the following conditionals have been ordered so that
* the most common cases appear first.
*/
if (tv.tv_sec == 0) {
if (tv.tv_usec == 0)
return (0);
exp = 0;
val = tv.tv_usec;
} else {
/*
* Calculate the value to a precision of approximately
* CALC_BITS.
*/
log2_s = fls(tv.tv_sec) - 1;
if (log2_s + LOG2_1M < CALC_BITS) {
exp = 0;
val = 1000000 * tv.tv_sec + tv.tv_usec;
} else {
exp = log2_s + LOG2_1M - CALC_BITS;
val = (unsigned int)(((uint64_t)1000000 * tv.tv_sec +
tv.tv_usec) >> exp);
}
}
/* Now normalize and pack the value into an IEEE-754 float. */
norm_exp = fls(val) - 1;
shift = FLT_MANT_DIG - norm_exp - 1;
#ifdef ACCT_DEBUG
printf("val=%d exp=%d shift=%d log2(val)=%d\n",
val, exp, shift, norm_exp);
printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp,
((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK));
#endif
return (((FLT_MAX_EXP - 1 + exp + norm_exp) << (FLT_MANT_DIG - 1)) |
((shift > 0 ? val << shift : val >> -shift) & MANT_MASK));
}
/*
* Convert a non-negative long value into the bit pattern of
* an IEEE-754 float value.
*/
static uint32_t
encode_long(long val)
{
int norm_exp; /* Normalized exponent */
int shift;
if (val == 0)
return (0);
if (val < 0) {
log(LOG_NOTICE,
"encode_long: negative value %ld in accounting record\n",
val);
val = LONG_MAX;
}
norm_exp = fls(val) - 1;
shift = FLT_MANT_DIG - norm_exp - 1;
#ifdef ACCT_DEBUG
printf("val=%d shift=%d log2(val)=%d\n",
val, shift, norm_exp);
printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp,
((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK));
#endif
return (((FLT_MAX_EXP - 1 + norm_exp) << (FLT_MANT_DIG - 1)) |
((shift > 0 ? val << shift : val >> -shift) & MANT_MASK));
}
/* FLOAT_CONVERSION_END (Regression testing; don't remove this line.) */
/*
* Periodically check the filesystem 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 */
static void
acctwatch(void)
{
struct statfs sb;
int vfslocked;
sx_assert(&acct_sx, SX_XLOCKED);
/*
* If accounting was disabled before our kthread was scheduled,
* then acct_vp might be NULL. If so, just ask our kthread to
* exit and return.
*/
if (acct_vp == NULL) {
acct_state |= ACCT_EXITREQ;
return;
}
/*
* If our vnode is no longer valid, tear it down and signal the
* accounting thread to die.
*/
vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
if (acct_vp->v_type == VBAD) {
(void) acct_disable(NULL);
VFS_UNLOCK_GIANT(vfslocked);
acct_state |= ACCT_EXITREQ;
return;
}
/*
* Stopping here is better than continuing, maybe it will be VBAD
* next time around.
*/
if (VFS_STATFS(acct_vp->v_mount, &sb) < 0) {
VFS_UNLOCK_GIANT(vfslocked);
return;
}
VFS_UNLOCK_GIANT(vfslocked);
if (acct_suspended) {
if (sb.f_bavail > (int64_t)(acctresume * sb.f_blocks /
100)) {
acct_suspended = 0;
log(LOG_NOTICE, "Accounting resumed\n");
}
} else {
if (sb.f_bavail <= (int64_t)(acctsuspend * sb.f_blocks /
100)) {
acct_suspended = 1;
log(LOG_NOTICE, "Accounting suspended\n");
}
}
}
/*
* The main loop for the dedicated kernel thread that periodically calls
* acctwatch().
*/
static void
acct_thread(void *dummy)
{
u_char pri;
/* This is a low-priority kernel thread. */
pri = PRI_MAX_KERN;
thread_lock(curthread);
sched_prio(curthread, pri);
thread_unlock(curthread);
/* If another accounting kthread is already running, just die. */
sx_xlock(&acct_sx);
if (acct_state & ACCT_RUNNING) {
sx_xunlock(&acct_sx);
kproc_exit(0);
}
acct_state |= ACCT_RUNNING;
/* Loop until we are asked to exit. */
while (!(acct_state & ACCT_EXITREQ)) {
/* Perform our periodic checks. */
acctwatch();
/*
* We check this flag again before sleeping since the
* acctwatch() might have shut down accounting and asked us
* to exit.
*/
if (!(acct_state & ACCT_EXITREQ)) {
sx_sleep(&acct_state, &acct_sx, 0, "-",
acctchkfreq * hz);
}
}
/*
* Acknowledge the exit request and shutdown. We clear both the
* exit request and running flags.
*/
acct_state = 0;
sx_xunlock(&acct_sx);
kproc_exit(0);
}