The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_acct.c

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    1 /*-
    2  * Copyright (c) 1994 Christopher G. Demetriou
    3  * Copyright (c) 1982, 1986, 1989, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  * (c) UNIX System Laboratories, Inc.
    6  * All or some portions of this file are derived from material licensed
    7  * to the University of California by American Telephone and Telegraph
    8  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    9  * the permission of UNIX System Laboratories, Inc.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
   36  * $FreeBSD: src/sys/kern/kern_acct.c,v 1.23.2.1 2002/07/24 18:33:55 johan Exp $
   37  */
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/sysproto.h>
   42 #include <sys/proc.h>
   43 #include <sys/priv.h>
   44 #include <sys/mount.h>
   45 #include <sys/vnode.h>
   46 #include <sys/fcntl.h>
   47 #include <sys/syslog.h>
   48 #include <sys/kernel.h>
   49 #include <sys/sysent.h>
   50 #include <sys/sysctl.h>
   51 #include <sys/nlookup.h>
   52 #include <sys/acct.h>
   53 #include <sys/resourcevar.h>
   54 #include <sys/tty.h>
   55 
   56 #include <vm/vm_zone.h>
   57 
   58 #include <sys/mplock2.h>
   59 
   60 /*
   61  * The routines implemented in this file are described in:
   62  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
   63  *          UNIX Operating System (Addison Welley, 1989)
   64  * on pages 62-63.
   65  *
   66  * Arguably, to simplify accounting operations, this mechanism should
   67  * be replaced by one in which an accounting log file (similar to /dev/klog)
   68  * is read by a user process, etc.  However, that has its own problems.
   69  */
   70 
   71 /*
   72  * Internal accounting functions.
   73  * The former's operation is described in Leffler, et al., and the latter
   74  * was provided by UCB with the 4.4BSD-Lite release
   75  */
   76 static comp_t   encode_comp_t (u_long, u_long);
   77 static void     acctwatch (void *);
   78 
   79 /*
   80  * Accounting callout handle used for periodic scheduling of
   81  * acctwatch.
   82  */
   83 static struct   callout acctwatch_handle;
   84 
   85 /*
   86  * Accounting vnode pointer, and saved vnode pointer.
   87  */
   88 static struct   vnode *acctp;
   89 static struct   vnode *savacctp;
   90 
   91 /*
   92  * Values associated with enabling and disabling accounting
   93  */
   94 static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
   95 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
   96         &acctsuspend, 0, "Percentage of free disk space below which accounting will be suspended");
   97 
   98 static int acctresume = 4;      /* resume when free space risen to > 4% */
   99 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
  100         &acctresume, 0, "Minimum percentage of free disk space needed to resume accounting");
  101 
  102 static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
  103 SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW,
  104         &acctchkfreq, 0, "Frequency (in seconds) of free disk space checking");
  105 
  106 static void
  107 acct_init(void *arg __unused)
  108 {
  109         callout_init(&acctwatch_handle);
  110 }
  111 SYSINIT(acct, SI_SUB_DRIVERS, SI_ORDER_ANY, acct_init, NULL);
  112 
  113 /*
  114  * Accounting system call.  Written based on the specification and
  115  * previous implementation done by Mark Tinguely.
  116  *
  117  * acct(char *path)
  118  *
  119  * MPALMOSTSAFE
  120  */
  121 int
  122 sys_acct(struct acct_args *uap)
  123 {
  124         struct thread *td = curthread;
  125         struct nlookupdata nd;
  126         struct vnode *vp;
  127         int error;
  128 
  129         error = priv_check(td, PRIV_ACCT);
  130         if (error)
  131                 return (error);
  132 
  133         get_mplock();
  134 
  135         /*
  136          * If accounting is to be started to a file, open that file for
  137          * appending and make sure it's a 'normal'.
  138          */
  139         if (uap->path != NULL) {
  140                 error = nlookup_init(&nd, uap->path, UIO_USERSPACE,
  141                                         NLC_LOCKVP);
  142                 if (error == 0)
  143                         error = vn_open(&nd, NULL, FWRITE | O_APPEND, 0);
  144                 if (error == 0 && nd.nl_open_vp->v_type != VREG) 
  145                         error = EACCES;
  146                 if (error) {
  147                         nlookup_done(&nd);
  148                         goto done;
  149                 }
  150                 vp = nd.nl_open_vp;
  151                 nd.nl_open_vp = NULL;
  152                 nlookup_done(&nd);
  153 
  154                 vn_unlock(vp);
  155         } else {
  156                 vp = NULL;
  157         }
  158 
  159         /*
  160          * If accounting was previously enabled, kill the old space-watcher,
  161          * close the file.
  162          */
  163         if (acctp != NULLVP || savacctp != NULLVP) {
  164                 callout_stop(&acctwatch_handle);
  165                 error = vn_close((acctp != NULLVP ? acctp : savacctp),
  166                                 FWRITE | O_APPEND);
  167                 acctp = savacctp = NULLVP;
  168         }
  169 
  170         /*
  171          * If no new file opened then leave.  We never did an nlookup so
  172          * don't try cleaning it up.
  173          */
  174         if (uap->path == NULL)
  175                 goto done;
  176 
  177         /*
  178          * Save the new accounting file vnode, and schedule the new
  179          * free space watcher.
  180          */
  181         acctp = vp;
  182         acctwatch(NULL);
  183 done:
  184         rel_mplock();
  185         return (error);
  186 }
  187 
  188 /*
  189  * Write out process accounting information, on process exit.
  190  * Data to be written out is specified in Leffler, et al.
  191  * and are enumerated below.  (They're also noted in the system
  192  * "acct.h" header file.)
  193  */
  194 
  195 int
  196 acct_process(struct proc *p)
  197 {
  198         struct acct acct;
  199         struct rusage *r;
  200         struct rusage ru;
  201         struct timeval tmp;
  202         struct rlimit rlim;
  203         int t;
  204         struct vnode *vp;
  205 
  206         /* If accounting isn't enabled, don't bother */
  207         vp = acctp;
  208         if (vp == NULLVP)
  209                 return (0);
  210 
  211         /*
  212          * Get process accounting information.
  213          */
  214 
  215         /* (1) The name of the command that ran */
  216         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
  217 
  218         /* (2) The amount of user and system time that was used */
  219         calcru_proc(p, &ru);
  220         acct.ac_utime = encode_comp_t(ru.ru_utime.tv_sec, ru.ru_utime.tv_usec);
  221         acct.ac_stime = encode_comp_t(ru.ru_stime.tv_sec, ru.ru_stime.tv_usec);
  222 
  223         /* (3) The elapsed time the commmand ran (and its starting time) */
  224         acct.ac_btime = p->p_start.tv_sec;
  225         microtime(&tmp);
  226         timevalsub(&tmp, &p->p_start);
  227         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
  228 
  229         /* (4) The average amount of memory used */
  230         r = &p->p_ru;
  231         tmp = ru.ru_utime;
  232         timevaladd(&tmp, &ru.ru_stime);
  233         t = tmp.tv_sec * hz + tmp.tv_usec / ustick;
  234         if (t)
  235                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
  236         else
  237                 acct.ac_mem = 0;
  238 
  239         /* (5) The number of disk I/O operations done */
  240         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
  241 
  242         /* (6) The UID and GID of the process */
  243         acct.ac_uid = p->p_ucred->cr_ruid;
  244         acct.ac_gid = p->p_ucred->cr_rgid;
  245 
  246         /* (7) The terminal from which the process was started */
  247         if ((p->p_flags & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  248                 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
  249         else
  250                 acct.ac_tty = NOUDEV;
  251 
  252         /* (8) The boolean flags that tell how the process terminated, etc. */
  253         acct.ac_flag = p->p_acflag;
  254 
  255         /*
  256          * Eliminate any file size rlimit.
  257          */
  258         rlim.rlim_cur = RLIM_INFINITY;
  259         rlim.rlim_max = RLIM_INFINITY;
  260         plimit_modify(p, RLIMIT_FSIZE, &rlim);
  261 
  262         /*
  263          * Write the accounting information to the file.
  264          */
  265         return (vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
  266             (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred,
  267             NULL));
  268 }
  269 
  270 /*
  271  * Encode_comp_t converts from ticks in seconds and microseconds
  272  * to ticks in 1/AHZ seconds.  The encoding is described in
  273  * Leffler, et al., on page 63.
  274  */
  275 
  276 #define MANTSIZE        13                      /* 13 bit mantissa. */
  277 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
  278 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
  279 
  280 static comp_t
  281 encode_comp_t(u_long s, u_long us)
  282 {
  283         int exp, rnd;
  284 
  285         exp = 0;
  286         rnd = 0;
  287         s *= AHZ;
  288         s += us / (1000000 / AHZ);      /* Maximize precision. */
  289 
  290         while (s > MAXFRACT) {
  291         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
  292                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
  293                 exp++;
  294         }
  295 
  296         /* If we need to round up, do it (and handle overflow correctly). */
  297         if (rnd && (++s > MAXFRACT)) {
  298                 s >>= EXPSIZE;
  299                 exp++;
  300         }
  301 
  302         /* Clean it up and polish it off. */
  303         exp <<= MANTSIZE;               /* Shift the exponent into place */
  304         exp += s;                       /* and add on the mantissa. */
  305         return (exp);
  306 }
  307 
  308 /*
  309  * Periodically check the file system to see if accounting
  310  * should be turned on or off.  Beware the case where the vnode
  311  * has been vgone()'d out from underneath us, e.g. when the file
  312  * system containing the accounting file has been forcibly unmounted.
  313  */
  314 /* ARGSUSED */
  315 static void
  316 acctwatch(void *a)
  317 {
  318         struct statfs sb;
  319 
  320         if (savacctp != NULLVP) {
  321                 if (savacctp->v_type == VBAD) {
  322                         (void) vn_close(savacctp, FWRITE | O_APPEND);
  323                         savacctp = NULLVP;
  324                         return;
  325                 }
  326                 (void)VFS_STATFS(savacctp->v_mount, &sb, proc0.p_ucred);
  327                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
  328                         acctp = savacctp;
  329                         savacctp = NULLVP;
  330                         log(LOG_NOTICE, "Accounting resumed\n");
  331                 }
  332         } else {
  333                 if (acctp == NULLVP)
  334                         return;
  335                 if (acctp->v_type == VBAD) {
  336                         (void) vn_close(acctp, FWRITE | O_APPEND);
  337                         acctp = NULLVP;
  338                         return;
  339                 }
  340                 (void)VFS_STATFS(acctp->v_mount, &sb, proc0.p_ucred);
  341                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
  342                         savacctp = acctp;
  343                         acctp = NULLVP;
  344                         log(LOG_NOTICE, "Accounting suspended\n");
  345                 }
  346         }
  347         callout_reset(&acctwatch_handle, acctchkfreq * hz, acctwatch, NULL);
  348 }

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