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. 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/sysmsg.h>
  42 #include <sys/proc.h>
  43 #include <sys/caps.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 static struct lock acct_lock = LOCK_INITIALIZER("acct_lock", 0, 0);
  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_lk(&acctwatch_handle, &acct_lock);
 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 sysmsg *sysmsg, const struct acct_args *uap)
 123 {
 124         struct nlookupdata nd;
 125         struct vnode *vp;
 126         int error;
 127
 128         error = caps_priv_check_self(SYSCAP_NOACCT);
 129         if (error)
 130                 return (error);
 131
 132         lockmgr(&acct_lock, LK_EXCLUSIVE);
 133
 134         /*
 135          * If accounting is to be started to a file, open that file for
 136          * appending and make sure it's a 'normal'.
 137          */
 138         if (uap->path != NULL) {
 139                 error = nlookup_init(&nd, uap->path, UIO_USERSPACE,
 140                                         NLC_LOCKVP);
 141                 if (error == 0)
 142                         error = vn_open(&nd, NULL, FWRITE | O_APPEND, 0);
 143                 if (error == 0 && nd.nl_open_vp->v_type != VREG)
 144                         error = EACCES;
 145                 if (error) {
 146                         nlookup_done(&nd);
 147                         goto done;
 148                 }
 149                 vp = nd.nl_open_vp;
 150                 nd.nl_open_vp = NULL;
 151                 nlookup_done(&nd);
 152
 153                 vn_unlock(vp);
 154         } else {
 155                 vp = NULL;
 156         }
 157
 158         /*
 159          * If accounting was previously enabled, kill the old space-watcher,
 160          * close the file.
 161          */
 162         if (acctp != NULLVP || savacctp != NULLVP) {
 163                 callout_stop(&acctwatch_handle);
 164                 error = vn_close((acctp != NULLVP ? acctp : savacctp),
 165                                 FWRITE | O_APPEND, NULL);
 166                 acctp = savacctp = NULLVP;
 167         }
 168
 169         /*
 170          * If no new file opened then leave.  We never did an nlookup so
 171          * don't try cleaning it up.
 172          */
 173         if (uap->path == NULL)
 174                 goto done;
 175
 176         /*
 177          * Save the new accounting file vnode, and schedule the new
 178          * free space watcher.
 179          */
 180         acctp = vp;
 181         acctwatch(NULL);
 182 done:
 183         lockmgr(&acct_lock, LK_RELEASE);
 184
 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         int error;
 205         struct vnode *vp;
 206
 207         /*
 208          * If accounting isn't enabled, don't bother.  Lock acct_lock
 209          * make sure.
 210          */
 211         if (acctp == NULLVP)
 212                 return 0;
 213         lockmgr(&acct_lock, LK_SHARED);
 214         vp = acctp;
 215         if (vp == NULLVP) {
 216                 lockmgr(&acct_lock, LK_RELEASE);
 217                 return 0;
 218         }
 219
 220         /*
 221          * Get process accounting information.
 222          */
 223
 224         /* (1) The name of the command that ran */
 225         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
 226
 227         /* (2) The amount of user and system time that was used */
 228         calcru_proc(p, &ru);
 229         acct.ac_utime = encode_comp_t(ru.ru_utime.tv_sec, ru.ru_utime.tv_usec);
 230         acct.ac_stime = encode_comp_t(ru.ru_stime.tv_sec, ru.ru_stime.tv_usec);
 231
 232         /* (3) The elapsed time the commmand ran (and its starting time) */
 233         acct.ac_btime = p->p_start.tv_sec;
 234         microtime(&tmp);
 235         timevalsub(&tmp, &p->p_start);
 236         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
 237
 238         /* (4) The average amount of memory used */
 239         r = &p->p_ru;
 240         tmp = ru.ru_utime;
 241         timevaladd(&tmp, &ru.ru_stime);
 242         t = tmp.tv_sec * hz + tmp.tv_usec / ustick;
 243         if (t)
 244                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
 245         else
 246                 acct.ac_mem = 0;
 247
 248         /* (5) The number of disk I/O operations done */
 249         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
 250
 251         /* (6) The UID and GID of the process */
 252         acct.ac_uid = p->p_ucred->cr_ruid;
 253         acct.ac_gid = p->p_ucred->cr_rgid;
 254
 255         /* (7) The terminal from which the process was started */
 256         if ((p->p_flags & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp) {
 257                 acct.ac_tty =
 258                     devid_from_dev(p->p_pgrp->pg_session->s_ttyp->t_dev);
 259         } else {
 260                 acct.ac_tty = NOUDEV;
 261         }
 262
 263         /* (8) The boolean flags that tell how the process terminated, etc. */
 264         acct.ac_flag = p->p_acflag;
 265
 266         /*
 267          * Eliminate any file size rlimit.
 268          */
 269         rlim.rlim_cur = RLIM_INFINITY;
 270         rlim.rlim_max = RLIM_INFINITY;
 271         plimit_modify(p, RLIMIT_FSIZE, &rlim);
 272
 273         /*
 274          * Write the accounting information to the file.
 275          */
 276         error = vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
 277                         (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred,
 278                         NULL);
 279         lockmgr(&acct_lock, LK_RELEASE);
 280
 281         return error;
 282 }
 283
 284 /*
 285  * Encode_comp_t converts from ticks in seconds and microseconds
 286  * to ticks in 1/AHZ seconds.  The encoding is described in
 287  * Leffler, et al., on page 63.
 288  */
 289
 290 #define MANTSIZE        13                      /* 13 bit mantissa. */
 291 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
 292 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
 293
 294 static comp_t
 295 encode_comp_t(u_long s, u_long us)
 296 {
 297         int exp, rnd;
 298
 299         exp = 0;
 300         rnd = 0;
 301         s *= AHZ;
 302         s += us / (1000000 / AHZ);      /* Maximize precision. */
 303
 304         while (s > MAXFRACT) {
 305         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
 306                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
 307                 exp++;
 308         }
 309
 310         /* If we need to round up, do it (and handle overflow correctly). */
 311         if (rnd && (++s > MAXFRACT)) {
 312                 s >>= EXPSIZE;
 313                 exp++;
 314         }
 315
 316         /* Clean it up and polish it off. */
 317         exp <<= MANTSIZE;               /* Shift the exponent into place */
 318         exp += s;                       /* and add on the mantissa. */
 319         return (exp);
 320 }
 321
 322 /*
 323  * Periodically check the file system to see if accounting
 324  * should be turned on or off.  Beware the case where the vnode
 325  * has been vgone()'d out from underneath us, e.g. when the file
 326  * system containing the accounting file has been forcibly unmounted.
 327  */
 328 /* ARGSUSED */
 329 static void
 330 acctwatch(void *a)
 331 {
 332         struct statfs sb;
 333
 334         if (savacctp != NULLVP) {
 335                 if (savacctp->v_type == VBAD) {
 336                         (void) vn_close(savacctp, FWRITE | O_APPEND, NULL);
 337                         savacctp = NULLVP;
 338                         return;
 339                 }
 340                 (void)VFS_STATFS(savacctp->v_mount, &sb, proc0.p_ucred);
 341                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
 342                         acctp = savacctp;
 343                         savacctp = NULLVP;
 344                         log(LOG_NOTICE, "Accounting resumed\n");
 345                 }
 346         } else {
 347                 if (acctp == NULLVP)
 348                         return;
 349                 if (acctp->v_type == VBAD) {
 350                         (void) vn_close(acctp, FWRITE | O_APPEND, NULL);
 351                         acctp = NULLVP;
 352                         return;
 353                 }
 354                 (void)VFS_STATFS(acctp->v_mount, &sb, proc0.p_ucred);
 355                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
 356                         savacctp = acctp;
 357                         acctp = NULLVP;
 358                         log(LOG_NOTICE, "Accounting suspended\n");
 359                 }
 360         }
 361         callout_reset(&acctwatch_handle, acctchkfreq * hz, acctwatch, NULL);
 362 }