kern_acct.c

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    1 /*      $NetBSD: kern_acct.c,v 1.86.12.1 2011/05/20 19:28:56 bouyer 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 1.86.12.1 2011/05/20 19:28:56 bouyer 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/kmem.h>
   86 #include <sys/namei.h>
   87 #include <sys/errno.h>
   88 #include <sys/acct.h>
   89 #include <sys/resourcevar.h>
   90 #include <sys/ioctl.h>
   91 #include <sys/tty.h>
   92 #include <sys/kauth.h>
   93 
   94 #include <sys/syscallargs.h>
   95 
   96 /*
   97  * The routines implemented in this file are described in:
   98  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
   99  *          UNIX Operating System (Addison Welley, 1989)
  100  * on pages 62-63.
  101  *
  102  * Arguably, to simplify accounting operations, this mechanism should
  103  * be replaced by one in which an accounting log file (similar to /dev/klog)
  104  * is read by a user process, etc.  However, that has its own problems.
  105  */
  106 
  107 /*
  108  * Lock to serialize system calls and kernel threads.
  109  */
  110 krwlock_t       acct_lock;
  111 
  112 /*
  113  * The global accounting state and related data.  Gain the mutex before
  114  * accessing these variables.
  115  */
  116 static enum {
  117         ACCT_STOP,
  118         ACCT_ACTIVE,
  119         ACCT_SUSPENDED
  120 } acct_state;                           /* The current accounting state. */
  121 static struct vnode *acct_vp;           /* Accounting vnode pointer. */
  122 static kauth_cred_t acct_cred;          /* Credential of accounting file
  123                                            owner (i.e root).  Used when
  124                                            accounting file i/o.  */
  125 static struct lwp *acct_dkwatcher;      /* Free disk space checker. */
  126 
  127 /*
  128  * Values associated with enabling and disabling accounting
  129  */
  130 int     acctsuspend = 2;        /* stop accounting when < 2% free space left */
  131 int     acctresume = 4;         /* resume when free space risen to > 4% */
  132 int     acctchkfreq = 15;       /* frequency (in seconds) to check space */
  133 
  134 /*
  135  * Encode_comp_t converts from ticks in seconds and microseconds
  136  * to ticks in 1/AHZ seconds.  The encoding is described in
  137  * Leffler, et al., on page 63.
  138  */
  139 
  140 #define MANTSIZE        13                      /* 13 bit mantissa. */
  141 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
  142 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
  143 
  144 static comp_t
  145 encode_comp_t(u_long s, u_long us)
  146 {
  147         int exp, rnd;
  148 
  149         exp = 0;
  150         rnd = 0;
  151         s *= AHZ;
  152         s += us / (1000000 / AHZ);      /* Maximize precision. */
  153 
  154         while (s > MAXFRACT) {
  155         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
  156                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
  157                 exp++;
  158         }
  159 
  160         /* If we need to round up, do it (and handle overflow correctly). */
  161         if (rnd && (++s > MAXFRACT)) {
  162                 s >>= EXPSIZE;
  163                 exp++;
  164         }
  165 
  166         /* Clean it up and polish it off. */
  167         exp <<= MANTSIZE;               /* Shift the exponent into place */
  168         exp += s;                       /* and add on the mantissa. */
  169         return (exp);
  170 }
  171 
  172 static int
  173 acct_chkfree(void)
  174 {
  175         int error;
  176         struct statvfs *sb;
  177         fsblkcnt_t bavail;
  178 
  179         sb = kmem_alloc(sizeof(*sb), KM_SLEEP);
  180         if (sb == NULL)
  181                 return (ENOMEM);
  182         error = VFS_STATVFS(acct_vp->v_mount, sb);
  183         if (error != 0) {
  184                 kmem_free(sb, sizeof(*sb));
  185                 return (error);
  186         }
  187 
  188         if (sb->f_bfree < sb->f_bresvd) {
  189                 bavail = 0;
  190         } else {
  191                 bavail = sb->f_bfree - sb->f_bresvd;
  192         }
  193 
  194         switch (acct_state) {
  195         case ACCT_SUSPENDED:
  196                 if (bavail > acctresume * sb->f_blocks / 100) {
  197                         acct_state = ACCT_ACTIVE;
  198                         log(LOG_NOTICE, "Accounting resumed\n");
  199                 }
  200                 break;
  201         case ACCT_ACTIVE:
  202                 if (bavail <= acctsuspend * sb->f_blocks / 100) {
  203                         acct_state = ACCT_SUSPENDED;
  204                         log(LOG_NOTICE, "Accounting suspended\n");
  205                 }
  206                 break;
  207         case ACCT_STOP:
  208                 break;
  209         }
  210         kmem_free(sb, sizeof(*sb));
  211         return (0);
  212 }
  213 
  214 static void
  215 acct_stop(void)
  216 {
  217         int error;
  218 
  219         KASSERT(rw_write_held(&acct_lock));
  220 
  221         if (acct_vp != NULLVP && acct_vp->v_type != VBAD) {
  222                 error = vn_close(acct_vp, FWRITE, acct_cred);
  223 #ifdef DIAGNOSTIC
  224                 if (error != 0)
  225                         printf("acct_stop: failed to close, errno = %d\n",
  226                             error);
  227 #endif
  228                 acct_vp = NULLVP;
  229         }
  230         if (acct_cred != NULL) {
  231                 kauth_cred_free(acct_cred);
  232                 acct_cred = NULL;
  233         }
  234         acct_state = ACCT_STOP;
  235 }
  236 
  237 /*
  238  * Periodically check the file system to see if accounting
  239  * should be turned on or off.  Beware the case where the vnode
  240  * has been vgone()'d out from underneath us, e.g. when the file
  241  * system containing the accounting file has been forcibly unmounted.
  242  */
  243 static void
  244 acctwatch(void *arg)
  245 {
  246         int error;
  247 
  248         log(LOG_NOTICE, "Accounting started\n");
  249         rw_enter(&acct_lock, RW_WRITER);
  250         while (acct_state != ACCT_STOP) {
  251                 if (acct_vp->v_type == VBAD) {
  252                         log(LOG_NOTICE, "Accounting terminated\n");
  253                         acct_stop();
  254                         continue;
  255                 }
  256 
  257                 error = acct_chkfree();
  258 #ifdef DIAGNOSTIC
  259                 if (error != 0)
  260                         printf("acctwatch: failed to statvfs, error = %d\n",
  261                             error);
  262 #endif
  263                 rw_exit(&acct_lock);
  264                 error = kpause("actwat", false, acctchkfreq * hz, NULL);
  265                 rw_enter(&acct_lock, RW_WRITER);
  266 #ifdef DIAGNOSTIC
  267                 if (error != 0 && error != EWOULDBLOCK)
  268                         printf("acctwatch: sleep error %d\n", error);
  269 #endif
  270         }
  271         acct_dkwatcher = NULL;
  272         rw_exit(&acct_lock);
  273 
  274         kthread_exit(0);
  275 }
  276 
  277 void
  278 acct_init(void)
  279 {
  280 
  281         acct_state = ACCT_STOP;
  282         acct_vp = NULLVP;
  283         acct_cred = NULL;
  284         rw_init(&acct_lock);
  285 }
  286 
  287 /*
  288  * Accounting system call.  Written based on the specification and
  289  * previous implementation done by Mark Tinguely.
  290  */
  291 int
  292 sys_acct(struct lwp *l, const struct sys_acct_args *uap, register_t *retval)
  293 {
  294         /* {
  295                 syscallarg(const char *) path;
  296         } */
  297         struct nameidata nd;
  298         int error;
  299 
  300         /* Make sure that the caller is root. */
  301         if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_ACCOUNTING,
  302             0, NULL, NULL, NULL)))
  303                 return (error);
  304 
  305         /*
  306          * If accounting is to be started to a file, open that file for
  307          * writing and make sure it's a 'normal'.
  308          */
  309         if (SCARG(uap, path) != NULL) {
  310                 struct vattr va;
  311                 size_t pad;
  312                 NDINIT(&nd, LOOKUP, NOFOLLOW | TRYEMULROOT, UIO_USERSPACE,
  313                     SCARG(uap, path));
  314                 if ((error = vn_open(&nd, FWRITE|O_APPEND, 0)) != 0)
  315                         return (error);
  316                 if (nd.ni_vp->v_type != VREG) {
  317                         VOP_UNLOCK(nd.ni_vp, 0);
  318                         error = EACCES;
  319                         goto bad;
  320                 }
  321                 if ((error = VOP_GETATTR(nd.ni_vp, &va, l->l_cred)) != 0) {
  322                         VOP_UNLOCK(nd.ni_vp, 0);
  323                         goto bad;
  324                 }
  325 
  326                 if ((pad = (va.va_size % sizeof(struct acct))) != 0) {
  327                         u_quad_t size = va.va_size - pad;
  328 #ifdef DIAGNOSTIC
  329                         printf("Size of accounting file not a multiple of "
  330                             "%lu - incomplete record truncated\n",
  331                             (unsigned long)sizeof(struct acct));
  332 #endif
  333                         VATTR_NULL(&va);
  334                         va.va_size = size;
  335                         error = VOP_SETATTR(nd.ni_vp, &va, l->l_cred);
  336                         if (error != 0) {
  337                                 VOP_UNLOCK(nd.ni_vp, 0);
  338                                 goto bad;
  339                         }
  340                 }
  341                 VOP_UNLOCK(nd.ni_vp, 0);
  342         }
  343 
  344         rw_enter(&acct_lock, RW_WRITER);
  345 
  346         /*
  347          * If accounting was previously enabled, kill the old space-watcher,
  348          * free credential for accounting file i/o,
  349          * ... (and, if no new file was specified, leave).
  350          */
  351         acct_stop();
  352         if (SCARG(uap, path) == NULL)
  353                 goto out;
  354 
  355         /*
  356          * Save the new accounting file vnode and credential,
  357          * and schedule the new free space watcher.
  358          */
  359         acct_state = ACCT_ACTIVE;
  360         acct_vp = nd.ni_vp;
  361         acct_cred = l->l_cred;
  362         kauth_cred_hold(acct_cred);
  363 
  364         error = acct_chkfree();         /* Initial guess. */
  365         if (error != 0) {
  366                 acct_stop();
  367                 goto out;
  368         }
  369 
  370         if (acct_dkwatcher == NULL) {
  371                 error = kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL,
  372                     acctwatch, NULL, &acct_dkwatcher, "acctwatch");
  373                 if (error != 0)
  374                         acct_stop();
  375         }
  376 
  377  out:
  378         rw_exit(&acct_lock);
  379         return (error);
  380  bad:
  381         vn_close(nd.ni_vp, FWRITE, l->l_cred);
  382         return error;
  383 }
  384 
  385 /*
  386  * Write out process accounting information, on process exit.
  387  * Data to be written out is specified in Leffler, et al.
  388  * and are enumerated below.  (They're also noted in the system
  389  * "acct.h" header file.)
  390  */
  391 int
  392 acct_process(struct lwp *l)
  393 {
  394         struct acct acct;
  395         struct timeval ut, st, tmp;
  396         struct rusage *r;
  397         int t, error = 0;
  398         struct rlimit orlim;
  399         struct proc *p = l->l_proc;
  400 
  401         if (acct_state != ACCT_ACTIVE)
  402                 return 0;
  403 
  404         rw_enter(&acct_lock, RW_READER);
  405 
  406         /* If accounting isn't enabled, don't bother */
  407         if (acct_state != ACCT_ACTIVE)
  408                 goto out;
  409 
  410         /*
  411          * Temporarily raise the file limit so that accounting can't
  412          * be stopped by the user.
  413          *
  414          * XXX We should think about the CPU limit, too.
  415          */
  416         lim_privatise(p, false);
  417         orlim = p->p_rlimit[RLIMIT_FSIZE];
  418         /* Set current and max to avoid illegal values */
  419         p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
  420         p->p_rlimit[RLIMIT_FSIZE].rlim_max = RLIM_INFINITY;
  421 
  422         /*
  423          * Get process accounting information.
  424          */
  425 
  426         /* (1) The name of the command that ran */
  427         memcpy(acct.ac_comm, p->p_comm, sizeof(acct.ac_comm));
  428 
  429         /* (2) The amount of user and system time that was used */
  430         mutex_enter(p->p_lock);
  431         calcru(p, &ut, &st, NULL, NULL);
  432         mutex_exit(p->p_lock);
  433         acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
  434         acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
  435 
  436         /* (3) The elapsed time the commmand ran (and its starting time) */
  437         acct.ac_btime = p->p_stats->p_start.tv_sec;
  438         getmicrotime(&tmp);
  439         timersub(&tmp, &p->p_stats->p_start, &tmp);
  440         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
  441 
  442         /* (4) The average amount of memory used */
  443         r = &p->p_stats->p_ru;
  444         timeradd(&ut, &st, &tmp);
  445         t = tmp.tv_sec * hz + tmp.tv_usec / tick;
  446         if (t)
  447                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
  448         else
  449                 acct.ac_mem = 0;
  450 
  451         /* (5) The number of disk I/O operations done */
  452         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
  453 
  454         /* (6) The UID and GID of the process */
  455         acct.ac_uid = kauth_cred_getuid(l->l_cred);
  456         acct.ac_gid = kauth_cred_getgid(l->l_cred);
  457 
  458         /* (7) The terminal from which the process was started */
  459         mutex_enter(proc_lock);
  460         if ((p->p_lflag & PL_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  461                 acct.ac_tty = p->p_pgrp->pg_session->s_ttyp->t_dev;
  462         else
  463                 acct.ac_tty = NODEV;
  464         mutex_exit(proc_lock);
  465 
  466         /* (8) The boolean flags that tell how the process terminated, etc. */
  467         acct.ac_flag = p->p_acflag;
  468 
  469         /*
  470          * Now, just write the accounting information to the file.
  471          */
  472         error = vn_rdwr(UIO_WRITE, acct_vp, (void *)&acct,
  473             sizeof(acct), (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT,
  474             acct_cred, NULL, NULL);
  475         if (error != 0)
  476                 log(LOG_ERR, "Accounting: write failed %d\n", error);
  477 
  478         /* Restore limit - rather pointless since process is about to exit */
  479         p->p_rlimit[RLIMIT_FSIZE] = orlim;
  480 
  481  out:
  482         rw_exit(&acct_lock);
  483         return (error);
  484 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_acct.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_acct.c
