sys/kern/kern_acct.c

   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  * $FreeBSD: src/sys/kern/kern_acct.c,v 1.23.2.1 2002/07/24 18:33:55 johan Exp $
  41  */
  42
  43 #include <sys/param.h>
  44 #include <sys/systm.h>
  45 #include <sys/sysproto.h>
  46 #include <sys/proc.h>
  47 #include <sys/priv.h>
  48 #include <sys/mount.h>
  49 #include <sys/vnode.h>
  50 #include <sys/fcntl.h>
  51 #include <sys/syslog.h>
  52 #include <sys/kernel.h>
  53 #include <sys/sysent.h>
  54 #include <sys/sysctl.h>
  55 #include <sys/nlookup.h>
  56 #include <sys/acct.h>
  57 #include <sys/resourcevar.h>
  58 #include <sys/tty.h>
  59
  60 #include <vm/vm_zone.h>
  61
  62 #include <sys/mplock2.h>
  63
  64 /*
  65  * The routines implemented in this file are described in:
  66  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
  67  *          UNIX Operating System (Addison Welley, 1989)
  68  * on pages 62-63.
  69  *
  70  * Arguably, to simplify accounting operations, this mechanism should
  71  * be replaced by one in which an accounting log file (similar to /dev/klog)
  72  * is read by a user process, etc.  However, that has its own problems.
  73  */
  74
  75 /*
  76  * Internal accounting functions.
  77  * The former's operation is described in Leffler, et al., and the latter
  78  * was provided by UCB with the 4.4BSD-Lite release
  79  */
  80 static comp_t   encode_comp_t (u_long, u_long);
  81 static void     acctwatch (void *);
  82
  83 /*
  84  * Accounting callout handle used for periodic scheduling of
  85  * acctwatch.
  86  */
  87 static struct   callout acctwatch_handle;
  88
  89 /*
  90  * Accounting vnode pointer, and saved vnode pointer.
  91  */
  92 static struct   vnode *acctp;
  93 static struct   vnode *savacctp;
  94
  95 /*
  96  * Values associated with enabling and disabling accounting
  97  */
  98 static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
  99 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
 100         &acctsuspend, 0, "Percentage of free disk space below which accounting will be suspended");
 101
 102 static int acctresume = 4;      /* resume when free space risen to > 4% */
 103 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
 104         &acctresume, 0, "Minimum percentage of free disk space needed to resume accounting");
 105
 106 static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
 107 SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW,
 108         &acctchkfreq, 0, "Frequency (in seconds) of free disk space checking");
 109
 110 static void
 111 acct_init(void *arg __unused)
 112 {
 113         callout_init(&acctwatch_handle);
 114 }
 115 SYSINIT(acct, SI_SUB_DRIVERS, SI_ORDER_ANY, acct_init, NULL);
 116
 117 /*
 118  * Accounting system call.  Written based on the specification and
 119  * previous implementation done by Mark Tinguely.
 120  *
 121  * acct(char *path)
 122  *
 123  * MPALMOSTSAFE
 124  */
 125 int
 126 sys_acct(struct acct_args *uap)
 127 {
 128         struct thread *td = curthread;
 129         struct nlookupdata nd;
 130         struct vnode *vp;
 131         int error;
 132
 133         error = priv_check(td, PRIV_ACCT);
 134         if (error)
 135                 return (error);
 136
 137         get_mplock();
 138
 139         /*
 140          * If accounting is to be started to a file, open that file for
 141          * appending and make sure it's a 'normal'.
 142          */
 143         if (uap->path != NULL) {
 144                 error = nlookup_init(&nd, uap->path, UIO_USERSPACE,
 145                                         NLC_LOCKVP);
 146                 if (error == 0)
 147                         error = vn_open(&nd, NULL, FWRITE | O_APPEND, 0);
 148                 if (error == 0 && nd.nl_open_vp->v_type != VREG)
 149                         error = EACCES;
 150                 if (error) {
 151                         nlookup_done(&nd);
 152                         goto done;
 153                 }
 154                 vp = nd.nl_open_vp;
 155                 nd.nl_open_vp = NULL;
 156                 nlookup_done(&nd);
 157
 158                 vn_unlock(vp);
 159         } else {
 160                 vp = NULL;
 161         }
 162
 163         /*
 164          * If accounting was previously enabled, kill the old space-watcher,
 165          * close the file.
 166          */
 167         if (acctp != NULLVP || savacctp != NULLVP) {
 168                 callout_stop(&acctwatch_handle);
 169                 error = vn_close((acctp != NULLVP ? acctp : savacctp),
 170                                 FWRITE | O_APPEND);
 171                 acctp = savacctp = NULLVP;
 172         }
 173
 174         /*
 175          * If no new file opened then leave.  We never did an nlookup so
 176          * don't try cleaning it up.
 177          */
 178         if (uap->path == NULL)
 179                 goto done;
 180
 181         /*
 182          * Save the new accounting file vnode, and schedule the new
 183          * free space watcher.
 184          */
 185         acctp = vp;
 186         acctwatch(NULL);
 187 done:
 188         rel_mplock();
 189         return (error);
 190 }
 191
 192 /*
 193  * Write out process accounting information, on process exit.
 194  * Data to be written out is specified in Leffler, et al.
 195  * and are enumerated below.  (They're also noted in the system
 196  * "acct.h" header file.)
 197  */
 198
 199 int
 200 acct_process(struct proc *p)
 201 {
 202         struct acct acct;
 203         struct rusage *r;
 204         struct rusage ru;
 205         struct timeval tmp;
 206         struct rlimit rlim;
 207         int t;
 208         struct vnode *vp;
 209
 210         /* If accounting isn't enabled, don't bother */
 211         vp = acctp;
 212         if (vp == NULLVP)
 213                 return (0);
 214
 215         /*
 216          * Get process accounting information.
 217          */
 218
 219         /* (1) The name of the command that ran */
 220         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
 221
 222         /* (2) The amount of user and system time that was used */
 223         calcru_proc(p, &ru);
 224         acct.ac_utime = encode_comp_t(ru.ru_utime.tv_sec, ru.ru_utime.tv_usec);
 225         acct.ac_stime = encode_comp_t(ru.ru_stime.tv_sec, ru.ru_stime.tv_usec);
 226
 227         /* (3) The elapsed time the commmand ran (and its starting time) */
 228         acct.ac_btime = p->p_start.tv_sec;
 229         microtime(&tmp);
 230         timevalsub(&tmp, &p->p_start);
 231         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
 232
 233         /* (4) The average amount of memory used */
 234         r = &p->p_ru;
 235         tmp = ru.ru_utime;
 236         timevaladd(&tmp, &ru.ru_stime);
 237         t = tmp.tv_sec * hz + tmp.tv_usec / ustick;
 238         if (t)
 239                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
 240         else
 241                 acct.ac_mem = 0;
 242
 243         /* (5) The number of disk I/O operations done */
 244         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
 245
 246         /* (6) The UID and GID of the process */
 247         acct.ac_uid = p->p_ucred->cr_ruid;
 248         acct.ac_gid = p->p_ucred->cr_rgid;
 249
 250         /* (7) The terminal from which the process was started */
 251         if ((p->p_flags & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
 252                 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
 253         else
 254                 acct.ac_tty = NOUDEV;
 255
 256         /* (8) The boolean flags that tell how the process terminated, etc. */
 257         acct.ac_flag = p->p_acflag;
 258
 259         /*
 260          * Eliminate any file size rlimit.
 261          */
 262         rlim.rlim_cur = RLIM_INFINITY;
 263         rlim.rlim_max = RLIM_INFINITY;
 264         plimit_modify(p, RLIMIT_FSIZE, &rlim);
 265
 266         /*
 267          * Write the accounting information to the file.
 268          */
 269         return (vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
 270             (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred,
 271             NULL));
 272 }
 273
 274 /*
 275  * Encode_comp_t converts from ticks in seconds and microseconds
 276  * to ticks in 1/AHZ seconds.  The encoding is described in
 277  * Leffler, et al., on page 63.
 278  */
 279
 280 #define MANTSIZE        13                      /* 13 bit mantissa. */
 281 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
 282 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
 283
 284 static comp_t
 285 encode_comp_t(u_long s, u_long us)
 286 {
 287         int exp, rnd;
 288
 289         exp = 0;
 290         rnd = 0;
 291         s *= AHZ;
 292         s += us / (1000000 / AHZ);      /* Maximize precision. */
 293
 294         while (s > MAXFRACT) {
 295         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
 296                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
 297                 exp++;
 298         }
 299
 300         /* If we need to round up, do it (and handle overflow correctly). */
 301         if (rnd && (++s > MAXFRACT)) {
 302                 s >>= EXPSIZE;
 303                 exp++;
 304         }
 305
 306         /* Clean it up and polish it off. */
 307         exp <<= MANTSIZE;               /* Shift the exponent into place */
 308         exp += s;                       /* and add on the mantissa. */
 309         return (exp);
 310 }
 311
 312 /*
 313  * Periodically check the file system to see if accounting
 314  * should be turned on or off.  Beware the case where the vnode
 315  * has been vgone()'d out from underneath us, e.g. when the file
 316  * system containing the accounting file has been forcibly unmounted.
 317  */
 318 /* ARGSUSED */
 319 static void
 320 acctwatch(void *a)
 321 {
 322         struct statfs sb;
 323
 324         if (savacctp != NULLVP) {
 325                 if (savacctp->v_type == VBAD) {
 326                         (void) vn_close(savacctp, FWRITE | O_APPEND);
 327                         savacctp = NULLVP;
 328                         return;
 329                 }
 330                 (void)VFS_STATFS(savacctp->v_mount, &sb, proc0.p_ucred);
 331                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
 332                         acctp = savacctp;
 333                         savacctp = NULLVP;
 334                         log(LOG_NOTICE, "Accounting resumed\n");
 335                 }
 336         } else {
 337                 if (acctp == NULLVP)
 338                         return;
 339                 if (acctp->v_type == VBAD) {
 340                         (void) vn_close(acctp, FWRITE | O_APPEND);
 341                         acctp = NULLVP;
 342                         return;
 343                 }
 344                 (void)VFS_STATFS(acctp->v_mount, &sb, proc0.p_ucred);
 345                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
 346                         savacctp = acctp;
 347                         acctp = NULLVP;
 348                         log(LOG_NOTICE, "Accounting suspended\n");
 349                 }
 350         }
 351         callout_reset(&acctwatch_handle, acctchkfreq * hz, acctwatch, NULL);
 352 }