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. All advertising materials mentioning features or use of this software
   20  *    must display the following acknowledgement:
   21  *      This product includes software developed by the University of
   22  *      California, Berkeley and its contributors.
   23  * 4. Neither the name of the University nor the names of its contributors
   24  *    may be used to endorse or promote products derived from this software
   25  *    without specific prior written permission.
   26  *
   27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   37  * SUCH DAMAGE.
   38  *
   39  *      @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
   40  */
   41 
   42 #include <sys/cdefs.h>
   43 __FBSDID("$FreeBSD: releng/5.4/sys/kern/kern_acct.c 145335 2005-04-20 19:11:07Z cvs2svn $");
   44 
   45 #include "opt_mac.h"
   46 
   47 #include <sys/param.h>
   48 #include <sys/systm.h>
   49 #include <sys/lock.h>
   50 #include <sys/mutex.h>
   51 #include <sys/sysproto.h>
   52 #include <sys/proc.h>
   53 #include <sys/mac.h>
   54 #include <sys/mount.h>
   55 #include <sys/vnode.h>
   56 #include <sys/fcntl.h>
   57 #include <sys/syslog.h>
   58 #include <sys/kernel.h>
   59 #include <sys/sysent.h>
   60 #include <sys/sysctl.h>
   61 #include <sys/namei.h>
   62 #include <sys/acct.h>
   63 #include <sys/resourcevar.h>
   64 #include <sys/tty.h>
   65 
   66 /*
   67  * The routines implemented in this file are described in:
   68  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
   69  *          UNIX Operating System (Addison Welley, 1989)
   70  * on pages 62-63.
   71  *
   72  * Arguably, to simplify accounting operations, this mechanism should
   73  * be replaced by one in which an accounting log file (similar to /dev/klog)
   74  * is read by a user process, etc.  However, that has its own problems.
   75  */
   76 
   77 /*
   78  * Internal accounting functions.
   79  * The former's operation is described in Leffler, et al., and the latter
   80  * was provided by UCB with the 4.4BSD-Lite release
   81  */
   82 static comp_t   encode_comp_t(u_long, u_long);
   83 static void     acctwatch(void *);
   84 
   85 /*
   86  * Accounting callout used for periodic scheduling of acctwatch.
   87  */
   88 static struct   callout acctwatch_callout;
   89 
   90 /*
   91  * Accounting vnode pointer, saved vnode pointer, and flags for each.
   92  */
   93 static struct   vnode *acctp;
   94 static struct   ucred *acctcred;
   95 static int      acctflags;
   96 static struct   vnode *savacctp;
   97 static struct   ucred *savacctcred;
   98 static int      savacctflags;
   99 
  100 static struct mtx       acct_mtx;
  101 MTX_SYSINIT(acct, &acct_mtx, "accounting", MTX_DEF);
  102 
  103 /*
  104  * Values associated with enabling and disabling accounting
  105  */
  106 static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
  107 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
  108         &acctsuspend, 0, "percentage of free disk space below which accounting stops");
  109 
  110 static int acctresume = 4;      /* resume when free space risen to > 4% */
  111 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
  112         &acctresume, 0, "percentage of free disk space above which accounting resumes");
  113 
  114 static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
  115 SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW,
  116         &acctchkfreq, 0, "frequency for checking the free space");
  117 
  118 /*
  119  * Accounting system call.  Written based on the specification and
  120  * previous implementation done by Mark Tinguely.
  121  *
  122  * MPSAFE
  123  */
  124 int
  125 acct(td, uap)
  126         struct thread *td;
  127         struct acct_args /* {
  128                 char *path;
  129         } */ *uap;
  130 {
  131         struct nameidata nd;
  132         int error, flags;
  133 
  134         /* Make sure that the caller is root. */
  135         error = suser(td);
  136         if (error)
  137                 return (error);
  138 
  139         mtx_lock(&Giant);
  140 
  141         /*
  142          * If accounting is to be started to a file, open that file for
  143          * appending and make sure it's a 'normal'.
  144          */
  145         if (uap->path != NULL) {
  146                 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, td);
  147                 flags = FWRITE | O_APPEND;
  148                 error = vn_open(&nd, &flags, 0, -1);
  149                 if (error)
  150                         goto done2;
  151                 NDFREE(&nd, NDF_ONLY_PNBUF);
  152 #ifdef MAC
  153                 error = mac_check_system_acct(td->td_ucred, nd.ni_vp);
  154                 if (error) {
  155                         vn_close(nd.ni_vp, flags, td->td_ucred, td);
  156                         goto done2;
  157                 }
  158 #endif
  159                 VOP_UNLOCK(nd.ni_vp, 0, td);
  160                 if (nd.ni_vp->v_type != VREG) {
  161                         vn_close(nd.ni_vp, flags, td->td_ucred, td);
  162                         error = EACCES;
  163                         goto done2;
  164                 }
  165 #ifdef MAC
  166         } else {
  167                 error = mac_check_system_acct(td->td_ucred, NULL);
  168                 if (error)
  169                         goto done2;
  170 #endif
  171         }
  172 
  173         mtx_lock(&acct_mtx);
  174 
  175         /*
  176          * If accounting was previously enabled, kill the old space-watcher,
  177          * close the file, and (if no new file was specified, leave).
  178          *
  179          * XXX arr: should not hold lock over vnode operation.
  180          */
  181         if (acctp != NULLVP || savacctp != NULLVP) {
  182                 callout_stop(&acctwatch_callout);
  183                 error = vn_close((acctp != NULLVP ? acctp : savacctp),
  184                     (acctp != NULLVP ? acctflags : savacctflags),
  185                     (acctcred != NOCRED ? acctcred : savacctcred), td);
  186                 acctp = savacctp = NULLVP;
  187                 crfree(acctcred != NOCRED ? acctcred : savacctcred);
  188                 acctcred = savacctcred = NOCRED;
  189                 log(LOG_NOTICE, "Accounting disabled\n");
  190         }
  191         if (uap->path == NULL) {
  192                 mtx_unlock(&acct_mtx);
  193                 goto done2;
  194         }
  195 
  196         /*
  197          * Save the new accounting file vnode, and schedule the new
  198          * free space watcher.
  199          */
  200         acctp = nd.ni_vp;
  201         acctcred = crhold(td->td_ucred);
  202         acctflags = flags;
  203         callout_init(&acctwatch_callout, 0);
  204         mtx_unlock(&acct_mtx);
  205         log(LOG_NOTICE, "Accounting enabled\n");
  206         acctwatch(NULL);
  207 
  208 done2:
  209         mtx_unlock(&Giant);
  210         return (error);
  211 }
  212 
  213 /*
  214  * Write out process accounting information, on process exit.
  215  * Data to be written out is specified in Leffler, et al.
  216  * and are enumerated below.  (They're also noted in the system
  217  * "acct.h" header file.)
  218  */
  219 int
  220 acct_process(td)
  221         struct thread *td;
  222 {
  223         struct acct acct;
  224         struct timeval ut, st, tmp;
  225         struct plimit *newlim, *oldlim;
  226         struct proc *p;
  227         struct rusage *r;
  228         struct ucred *uc;
  229         struct vnode *vp;
  230         int t, ret;
  231 
  232         /*
  233          * Lockless check of accounting condition before doing the hard
  234          * work.
  235          */
  236         if (acctp == NULLVP)
  237                 return (0);
  238 
  239         mtx_lock(&acct_mtx);
  240 
  241         /*
  242          * If accounting isn't enabled, don't bother.  Have to check again
  243          * once we own the lock in case we raced with disabling of accounting
  244          * by another thread.
  245          */
  246         vp = acctp;
  247         if (vp == NULLVP) {
  248                 mtx_unlock(&acct_mtx);
  249                 return (0);
  250         }
  251 
  252         p = td->td_proc;
  253 
  254         /*
  255          * Get process accounting information.
  256          */
  257 
  258         PROC_LOCK(p);
  259         /* (1) The name of the command that ran */
  260         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
  261 
  262         /* (2) The amount of user and system time that was used */
  263         mtx_lock_spin(&sched_lock);
  264         calcru(p, &ut, &st, NULL);
  265         mtx_unlock_spin(&sched_lock);
  266         acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
  267         acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
  268 
  269         /* (3) The elapsed time the command ran (and its starting time) */
  270         tmp = boottime;
  271         timevaladd(&tmp, &p->p_stats->p_start);
  272         acct.ac_btime = tmp.tv_sec;
  273         microuptime(&tmp);
  274         timevalsub(&tmp, &p->p_stats->p_start);
  275         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
  276 
  277         /* (4) The average amount of memory used */
  278         r = &p->p_stats->p_ru;
  279         tmp = ut;
  280         timevaladd(&tmp, &st);
  281         t = tmp.tv_sec * hz + tmp.tv_usec / tick;
  282         if (t)
  283                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
  284         else
  285                 acct.ac_mem = 0;
  286 
  287         /* (5) The number of disk I/O operations done */
  288         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
  289 
  290         /* (6) The UID and GID of the process */
  291         acct.ac_uid = p->p_ucred->cr_ruid;
  292         acct.ac_gid = p->p_ucred->cr_rgid;
  293 
  294         /* (7) The terminal from which the process was started */
  295         SESS_LOCK(p->p_session);
  296         if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  297                 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
  298         else
  299                 acct.ac_tty = NODEV;
  300         SESS_UNLOCK(p->p_session);
  301 
  302         /* (8) The boolean flags that tell how the process terminated, etc. */
  303         acct.ac_flag = p->p_acflag;
  304         PROC_UNLOCK(p);
  305 
  306         /*
  307          * Finish doing things that require acct_mtx, and release acct_mtx.
  308          */
  309         uc = crhold(acctcred);
  310         vref(vp);
  311         mtx_unlock(&acct_mtx);
  312 
  313         /*
  314          * Eliminate any file size rlimit.
  315          */
  316         newlim = lim_alloc();
  317         PROC_LOCK(p);
  318         oldlim = p->p_limit;
  319         lim_copy(newlim, oldlim);
  320         newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
  321         p->p_limit = newlim;
  322         PROC_UNLOCK(p);
  323         lim_free(oldlim);
  324 
  325         /*
  326          * Write the accounting information to the file.
  327          */
  328         VOP_LEASE(vp, td, uc, LEASE_WRITE);
  329         ret = vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
  330             (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, uc, NOCRED,
  331             (int *)0, td);
  332         vrele(vp);
  333         crfree(uc);
  334         return (ret);
  335 }
  336 
  337 /*
  338  * Encode_comp_t converts from ticks in seconds and microseconds
  339  * to ticks in 1/AHZ seconds.  The encoding is described in
  340  * Leffler, et al., on page 63.
  341  */
  342 
  343 #define MANTSIZE        13                      /* 13 bit mantissa. */
  344 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
  345 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
  346 
  347 static comp_t
  348 encode_comp_t(s, us)
  349         u_long s, us;
  350 {
  351         int exp, rnd;
  352 
  353         exp = 0;
  354         rnd = 0;
  355         s *= AHZ;
  356         s += us / (1000000 / AHZ);      /* Maximize precision. */
  357 
  358         while (s > MAXFRACT) {
  359         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
  360                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
  361                 exp++;
  362         }
  363 
  364         /* If we need to round up, do it (and handle overflow correctly). */
  365         if (rnd && (++s > MAXFRACT)) {
  366                 s >>= EXPSIZE;
  367                 exp++;
  368         }
  369 
  370         /* Clean it up and polish it off. */
  371         exp <<= MANTSIZE;               /* Shift the exponent into place */
  372         exp += s;                       /* and add on the mantissa. */
  373         return (exp);
  374 }
  375 
  376 /*
  377  * Periodically check the filesystem to see if accounting
  378  * should be turned on or off.  Beware the case where the vnode
  379  * has been vgone()'d out from underneath us, e.g. when the file
  380  * system containing the accounting file has been forcibly unmounted.
  381  */
  382 /* ARGSUSED */
  383 static void
  384 acctwatch(a)
  385         void *a;
  386 {
  387         struct statfs sb;
  388 
  389         mtx_lock(&acct_mtx);
  390 
  391         /*
  392          * XXX arr: need to fix the issue of holding acct_mtx over
  393          * the below vnode operations.
  394          */
  395         if (savacctp != NULLVP) {
  396                 if (savacctp->v_type == VBAD) {
  397                         (void) vn_close(savacctp, savacctflags, savacctcred,
  398                             NULL);
  399                         savacctp = NULLVP;
  400                         savacctcred = NOCRED;
  401                         mtx_unlock(&acct_mtx);
  402                         return;
  403                 }
  404                 (void)VFS_STATFS(savacctp->v_mount, &sb, (struct thread *)0);
  405                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
  406                         acctp = savacctp;
  407                         acctcred = savacctcred;
  408                         acctflags = savacctflags;
  409                         savacctp = NULLVP;
  410                         savacctcred = NOCRED;
  411                         log(LOG_NOTICE, "Accounting resumed\n");
  412                 }
  413         } else {
  414                 if (acctp == NULLVP) {
  415                         mtx_unlock(&acct_mtx);
  416                         return;
  417                 }
  418                 if (acctp->v_type == VBAD) {
  419                         (void) vn_close(acctp, acctflags, acctcred, NULL);
  420                         acctp = NULLVP;
  421                         crfree(acctcred);
  422                         acctcred = NOCRED;
  423                         mtx_unlock(&acct_mtx);
  424                         return;
  425                 }
  426                 (void)VFS_STATFS(acctp->v_mount, &sb, (struct thread *)0);
  427                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
  428                         savacctp = acctp;
  429                         savacctflags = acctflags;
  430                         savacctcred = acctcred;
  431                         acctp = NULLVP;
  432                         acctcred = NOCRED;
  433                         log(LOG_NOTICE, "Accounting suspended\n");
  434                 }
  435         }
  436         callout_reset(&acctwatch_callout, acctchkfreq * hz, acctwatch, NULL);
  437         mtx_unlock(&acct_mtx);
  438 }

Cache object: 313a30e71410358a3f79dea2827ab62f


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