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 /*      $NetBSD: kern_acct.c,v 1.60 2004/12/13 08:46:43 yamt Exp $      */
    2 
    3 /*-
    4  * Copyright (c) 1982, 1986, 1989, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * (c) UNIX System Laboratories, Inc.
    7  * All or some portions of this file are derived from material licensed
    8  * to the University of California by American Telephone and Telegraph
    9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   10  * the permission of UNIX System Laboratories, Inc.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)kern_acct.c 8.8 (Berkeley) 5/14/95
   37  */
   38 
   39 /*-
   40  * Copyright (c) 1994 Christopher G. Demetriou
   41  *
   42  * Redistribution and use in source and binary forms, with or without
   43  * modification, are permitted provided that the following conditions
   44  * are met:
   45  * 1. Redistributions of source code must retain the above copyright
   46  *    notice, this list of conditions and the following disclaimer.
   47  * 2. Redistributions in binary form must reproduce the above copyright
   48  *    notice, this list of conditions and the following disclaimer in the
   49  *    documentation and/or other materials provided with the distribution.
   50  * 3. All advertising materials mentioning features or use of this software
   51  *    must display the following acknowledgement:
   52  *      This product includes software developed by the University of
   53  *      California, Berkeley and its contributors.
   54  * 4. Neither the name of the University nor the names of its contributors
   55  *    may be used to endorse or promote products derived from this software
   56  *    without specific prior written permission.
   57  *
   58  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   59  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   60  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   61  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   62  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   63  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   64  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   65  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   66  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   67  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   68  * SUCH DAMAGE.
   69  *
   70  *      @(#)kern_acct.c 8.8 (Berkeley) 5/14/95
   71  */
   72 
   73 #include <sys/cdefs.h>
   74 __KERNEL_RCSID(0, "$NetBSD: kern_acct.c,v 1.60 2004/12/13 08:46:43 yamt Exp $");
   75 
   76 #include <sys/param.h>
   77 #include <sys/systm.h>
   78 #include <sys/proc.h>
   79 #include <sys/mount.h>
   80 #include <sys/vnode.h>
   81 #include <sys/file.h>
   82 #include <sys/syslog.h>
   83 #include <sys/kernel.h>
   84 #include <sys/kthread.h>
   85 #include <sys/lock.h>
   86 #include <sys/malloc.h>
   87 #include <sys/namei.h>
   88 #include <sys/errno.h>
   89 #include <sys/acct.h>
   90 #include <sys/resourcevar.h>
   91 #include <sys/ioctl.h>
   92 #include <sys/tty.h>
   93 
   94 #include <sys/sa.h>
   95 #include <sys/syscallargs.h>
   96 
   97 /*
   98  * The routines implemented in this file are described in:
   99  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
  100  *          UNIX Operating System (Addison Welley, 1989)
  101  * on pages 62-63.
  102  *
  103  * Arguably, to simplify accounting operations, this mechanism should
  104  * be replaced by one in which an accounting log file (similar to /dev/klog)
  105  * is read by a user process, etc.  However, that has its own problems.
  106  */
  107 
  108 /*
  109  * The global accounting state and related data.  Gain the lock before
  110  * accessing these variables.
  111  */
  112 enum {
  113         ACCT_STOP,
  114         ACCT_ACTIVE,
  115         ACCT_SUSPENDED
  116 } acct_state;                           /* The current accounting state. */
  117 struct vnode *acct_vp;                  /* Accounting vnode pointer. */
  118 struct ucred *acct_ucred;               /* Credential of accounting file
  119                                            owner (i.e root).  Used when
  120                                            accounting file i/o.  */
  121 struct proc *acct_dkwatcher;            /* Free disk space checker. */
  122 
  123 /*
  124  * Lock to serialize system calls and kernel threads.
  125  */
  126 struct  lock acct_lock;
  127 #define ACCT_LOCK()                                             \
  128 do {                                                            \
  129         (void) lockmgr(&acct_lock, LK_EXCLUSIVE, NULL);         \
  130 } while (/* CONSTCOND */0)
  131 #define ACCT_UNLOCK()                                           \
  132 do {                                                            \
  133         (void) lockmgr(&acct_lock, LK_RELEASE, NULL);           \
  134 } while (/* CONSTCOND */0)
  135 
  136 /*
  137  * Internal accounting functions.
  138  * The former's operation is described in Leffler, et al., and the latter
  139  * was provided by UCB with the 4.4BSD-Lite release
  140  */
  141 comp_t  encode_comp_t(u_long, u_long);
  142 void    acctwatch(void *);
  143 void    acct_stop(void);
  144 int     acct_chkfree(void);
  145 
  146 /*
  147  * Values associated with enabling and disabling accounting
  148  */
  149 int     acctsuspend = 2;        /* stop accounting when < 2% free space left */
  150 int     acctresume = 4;         /* resume when free space risen to > 4% */
  151 int     acctchkfreq = 15;       /* frequency (in seconds) to check space */
  152 
  153 void
  154 acct_init()
  155 {
  156 
  157         acct_state = ACCT_STOP;
  158         acct_vp = NULLVP;
  159         acct_ucred = NULL;
  160         lockinit(&acct_lock, PWAIT, "acctlk", 0, 0);
  161 }
  162 
  163 void
  164 acct_stop()
  165 {
  166         int error;
  167 
  168         if (acct_vp != NULLVP && acct_vp->v_type != VBAD) {
  169                 error = vn_close(acct_vp, FWRITE, acct_ucred, NULL);
  170 #ifdef DIAGNOSTIC
  171                 if (error != 0)
  172                         printf("acct_stop: failed to close, errno = %d\n",
  173                             error);
  174 #endif
  175                 acct_vp = NULLVP;
  176         }
  177         if (acct_ucred != NULL) {
  178                 crfree(acct_ucred);
  179                 acct_ucred = NULL;
  180         }
  181         acct_state = ACCT_STOP;
  182 }
  183 
  184 int
  185 acct_chkfree()
  186 {
  187         int error;
  188         struct statvfs sb;
  189         int64_t bavail;
  190 
  191         error = VFS_STATVFS(acct_vp->v_mount, &sb, NULL);
  192         if (error != 0)
  193                 return (error);
  194 
  195         bavail = sb.f_bfree - sb.f_bresvd;
  196 
  197         switch (acct_state) {
  198         case ACCT_SUSPENDED:
  199                 if (bavail > acctresume * sb.f_blocks / 100) {
  200                         acct_state = ACCT_ACTIVE;
  201                         log(LOG_NOTICE, "Accounting resumed\n");
  202                 }
  203                 break;
  204         case ACCT_ACTIVE:
  205                 if (bavail <= acctsuspend * sb.f_blocks / 100) {
  206                         acct_state = ACCT_SUSPENDED;
  207                         log(LOG_NOTICE, "Accounting suspended\n");
  208                 }
  209                 break;
  210         case ACCT_STOP:
  211                 break;
  212         }
  213         return (0);
  214 }
  215 
  216 /*
  217  * Accounting system call.  Written based on the specification and
  218  * previous implementation done by Mark Tinguely.
  219  */
  220 int
  221 sys_acct(l, v, retval)
  222         struct lwp *l;
  223         void *v;
  224         register_t *retval;
  225 {
  226         struct sys_acct_args /* {
  227                 syscallarg(const char *) path;
  228         } */ *uap = v;
  229         struct nameidata nd;
  230         int error;
  231         struct proc *p = l->l_proc;
  232 
  233         /* Make sure that the caller is root. */
  234         if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
  235                 return (error);
  236 
  237         /*
  238          * If accounting is to be started to a file, open that file for
  239          * writing and make sure it's a 'normal'.
  240          */
  241         if (SCARG(uap, path) != NULL) {
  242                 struct vattr va;
  243                 size_t pad;
  244                 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, SCARG(uap, path),
  245                     p);
  246                 if ((error = vn_open(&nd, FWRITE|O_APPEND, 0)) != 0)
  247                         return (error);
  248                 if (nd.ni_vp->v_type != VREG) {
  249                         VOP_UNLOCK(nd.ni_vp, 0);
  250                         error = EACCES;
  251                         goto bad;
  252                 }
  253                 if ((error = VOP_GETATTR(nd.ni_vp, &va, p->p_ucred, p)) != 0) {
  254                         VOP_UNLOCK(nd.ni_vp, 0);
  255                         goto bad;
  256                 }
  257 
  258                 if ((pad = (va.va_size % sizeof(struct acct))) != 0) {
  259                         u_quad_t size = va.va_size - pad;
  260 #ifdef DIAGNOSTIC
  261                         printf("Size of accounting file not a multiple of "
  262                             "%lu - incomplete record truncated\n",
  263                             (unsigned long)sizeof(struct acct));
  264 #endif
  265                         VATTR_NULL(&va);
  266                         va.va_size = size;
  267                         error = VOP_SETATTR(nd.ni_vp, &va, p->p_ucred, p);
  268                         if (error != 0) {
  269                                 VOP_UNLOCK(nd.ni_vp, 0);
  270                                 goto bad;
  271                         }
  272                 }
  273                 VOP_UNLOCK(nd.ni_vp, 0);
  274         }
  275 
  276         ACCT_LOCK();
  277 
  278         /*
  279          * If accounting was previously enabled, kill the old space-watcher,
  280          * free credential for accounting file i/o,
  281          * ... (and, if no new file was specified, leave).
  282          */
  283         acct_stop();
  284         if (SCARG(uap, path) == NULL)
  285                 goto out;
  286 
  287         /*
  288          * Save the new accounting file vnode and credential,
  289          * and schedule the new free space watcher.
  290          */
  291         acct_state = ACCT_ACTIVE;
  292         acct_vp = nd.ni_vp;
  293         acct_ucred = p->p_ucred;
  294         crhold(acct_ucred);
  295 
  296         error = acct_chkfree();         /* Initial guess. */
  297         if (error != 0) {
  298                 acct_stop();
  299                 goto out;
  300         }
  301 
  302         if (acct_dkwatcher == NULL) {
  303                 error = kthread_create1(acctwatch, NULL, &acct_dkwatcher,
  304                     "acctwatch");
  305                 if (error != 0)
  306                         acct_stop();
  307         }
  308 
  309  out:
  310         ACCT_UNLOCK();
  311         return (error);
  312  bad:
  313         vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
  314         return error;
  315 }
  316 
  317 /*
  318  * Write out process accounting information, on process exit.
  319  * Data to be written out is specified in Leffler, et al.
  320  * and are enumerated below.  (They're also noted in the system
  321  * "acct.h" header file.)
  322  */
  323 int
  324 acct_process(p)
  325         struct proc *p;
  326 {
  327         struct acct acct;
  328         struct rusage *r;
  329         struct timeval ut, st, tmp;
  330         int s, t, error = 0;
  331         struct plimit *oplim = NULL;
  332 
  333         ACCT_LOCK();
  334 
  335         /* If accounting isn't enabled, don't bother */
  336         if (acct_state != ACCT_ACTIVE)
  337                 goto out;
  338 
  339         /*
  340          * Raise the file limit so that accounting can't be stopped by
  341          * the user.
  342          *
  343          * XXX We should think about the CPU limit, too.
  344          */
  345         if (p->p_limit->p_refcnt > 1) {
  346                 oplim = p->p_limit;
  347                 p->p_limit = limcopy(p->p_limit);
  348         }
  349         p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
  350 
  351         /*
  352          * Get process accounting information.
  353          */
  354 
  355         /* (1) The name of the command that ran */
  356         memcpy(acct.ac_comm, p->p_comm, sizeof(acct.ac_comm));
  357 
  358         /* (2) The amount of user and system time that was used */
  359         calcru(p, &ut, &st, NULL);
  360         acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
  361         acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
  362 
  363         /* (3) The elapsed time the commmand ran (and its starting time) */
  364         acct.ac_btime = p->p_stats->p_start.tv_sec;
  365         s = splclock();
  366         timersub(&time, &p->p_stats->p_start, &tmp);
  367         splx(s);
  368         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
  369 
  370         /* (4) The average amount of memory used */
  371         r = &p->p_stats->p_ru;
  372         timeradd(&ut, &st, &tmp);
  373         t = tmp.tv_sec * hz + tmp.tv_usec / tick;
  374         if (t)
  375                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
  376         else
  377                 acct.ac_mem = 0;
  378 
  379         /* (5) The number of disk I/O operations done */
  380         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
  381 
  382         /* (6) The UID and GID of the process */
  383         acct.ac_uid = p->p_cred->p_ruid;
  384         acct.ac_gid = p->p_cred->p_rgid;
  385 
  386         /* (7) The terminal from which the process was started */
  387         if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  388                 acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
  389         else
  390                 acct.ac_tty = NODEV;
  391 
  392         /* (8) The boolean flags that tell how the process terminated, etc. */
  393         acct.ac_flag = p->p_acflag;
  394 
  395         /*
  396          * Now, just write the accounting information to the file.
  397          */
  398         VOP_LEASE(acct_vp, p, p->p_ucred, LEASE_WRITE);
  399         error = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct,
  400             sizeof(acct), (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT,
  401             acct_ucred, NULL, NULL);
  402         if (error != 0)
  403                 log(LOG_ERR, "Accounting: write failed %d\n", error);
  404 
  405         if (oplim) {
  406                 limfree(p->p_limit);
  407                 p->p_limit = oplim;
  408         }
  409 
  410  out:
  411         ACCT_UNLOCK();
  412         return (error);
  413 }
  414 
  415 /*
  416  * Encode_comp_t converts from ticks in seconds and microseconds
  417  * to ticks in 1/AHZ seconds.  The encoding is described in
  418  * Leffler, et al., on page 63.
  419  */
  420 
  421 #define MANTSIZE        13                      /* 13 bit mantissa. */
  422 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
  423 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
  424 
  425 comp_t
  426 encode_comp_t(s, us)
  427         u_long s, us;
  428 {
  429         int exp, rnd;
  430 
  431         exp = 0;
  432         rnd = 0;
  433         s *= AHZ;
  434         s += us / (1000000 / AHZ);      /* Maximize precision. */
  435 
  436         while (s > MAXFRACT) {
  437         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
  438                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
  439                 exp++;
  440         }
  441 
  442         /* If we need to round up, do it (and handle overflow correctly). */
  443         if (rnd && (++s > MAXFRACT)) {
  444                 s >>= EXPSIZE;
  445                 exp++;
  446         }
  447 
  448         /* Clean it up and polish it off. */
  449         exp <<= MANTSIZE;               /* Shift the exponent into place */
  450         exp += s;                       /* and add on the mantissa. */
  451         return (exp);
  452 }
  453 
  454 /*
  455  * Periodically check the file system to see if accounting
  456  * should be turned on or off.  Beware the case where the vnode
  457  * has been vgone()'d out from underneath us, e.g. when the file
  458  * system containing the accounting file has been forcibly unmounted.
  459  */
  460 void
  461 acctwatch(arg)
  462         void *arg;
  463 {
  464         int error;
  465 
  466         log(LOG_NOTICE, "Accounting started\n");
  467         ACCT_LOCK();
  468         while (acct_state != ACCT_STOP) {
  469                 if (acct_vp->v_type == VBAD) {
  470                         log(LOG_NOTICE, "Accounting terminated\n");
  471                         acct_stop();
  472                         continue;
  473                 }
  474 
  475                 error = acct_chkfree();
  476 #ifdef DIAGNOSTIC
  477                 if (error != 0)
  478                         printf("acctwatch: failed to statvfs, error = %d\n",
  479                             error);
  480 #endif
  481 
  482                 ACCT_UNLOCK();
  483                 error = tsleep(acctwatch, PSWP, "actwat", acctchkfreq * hz);
  484                 ACCT_LOCK();
  485 #ifdef DIAGNOSTIC
  486                 if (error != 0 && error != EWOULDBLOCK)
  487                         printf("acctwatch: sleep error %d\n", error);
  488 #endif
  489         }
  490         acct_dkwatcher = NULL;
  491         ACCT_UNLOCK();
  492 
  493         kthread_exit(0);
  494 }

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