Now available: 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 * $FreeBSD: releng/5.0/sys/kern/kern_acct.c 108086 2002-12-19 09:40:13Z alfred $ 41 */ 42 43 #include "opt_mac.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/lock.h> 48 #include <sys/mutex.h> 49 #include <sys/sysproto.h> 50 #include <sys/proc.h> 51 #include <sys/mac.h> 52 #include <sys/mount.h> 53 #include <sys/vnode.h> 54 #include <sys/fcntl.h> 55 #include <sys/syslog.h> 56 #include <sys/kernel.h> 57 #include <sys/sysent.h> 58 #include <sys/sysctl.h> 59 #include <sys/namei.h> 60 #include <sys/acct.h> 61 #include <sys/resourcevar.h> 62 #include <sys/tty.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 used for periodic scheduling of acctwatch. 85 */ 86 static struct callout acctwatch_callout; 87 88 /* 89 * Accounting vnode pointer, saved vnode pointer, and flags for each. 90 */ 91 static struct vnode *acctp; 92 static struct ucred *acctcred; 93 static int acctflags; 94 static struct vnode *savacctp; 95 static struct ucred *savacctcred; 96 static int savacctflags; 97 98 static struct mtx acct_mtx; 99 MTX_SYSINIT(acct, &acct_mtx, "accounting", MTX_DEF); 100 101 /* 102 * Values associated with enabling and disabling accounting 103 */ 104 static int acctsuspend = 2; /* stop accounting when < 2% free space left */ 105 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW, 106 &acctsuspend, 0, "percentage of free disk space below which accounting stops"); 107 108 static int acctresume = 4; /* resume when free space risen to > 4% */ 109 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW, 110 &acctresume, 0, "percentage of free disk space above which accounting resumes"); 111 112 static int acctchkfreq = 15; /* frequency (in seconds) to check space */ 113 SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW, 114 &acctchkfreq, 0, "frequency for checking the free space"); 115 116 /* 117 * Accounting system call. Written based on the specification and 118 * previous implementation done by Mark Tinguely. 119 * 120 * MPSAFE 121 */ 122 int 123 acct(td, uap) 124 struct thread *td; 125 struct acct_args /* { 126 char *path; 127 } */ *uap; 128 { 129 struct nameidata nd; 130 int error, flags; 131 132 /* Make sure that the caller is root. */ 133 error = suser(td); 134 if (error) 135 return (error); 136 137 mtx_lock(&Giant); 138 /* 139 * If accounting is to be started to a file, open that file for 140 * appending and make sure it's a 'normal'. 141 */ 142 if (uap->path != NULL) { 143 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, 144 td); 145 flags = FWRITE | O_APPEND; 146 error = vn_open(&nd, &flags, 0); 147 if (error) 148 goto done2; 149 NDFREE(&nd, NDF_ONLY_PNBUF); 150 #ifdef MAC 151 error = mac_check_system_acct(td->td_ucred, nd.ni_vp); 152 if (error) { 153 vn_close(nd.ni_vp, flags, td->td_ucred, td); 154 goto done2; 155 } 156 #endif 157 VOP_UNLOCK(nd.ni_vp, 0, td); 158 if (nd.ni_vp->v_type != VREG) { 159 vn_close(nd.ni_vp, flags, td->td_ucred, td); 160 error = EACCES; 161 goto done2; 162 } 163 #ifdef MAC 164 } else { 165 error = mac_check_system_acct(td->td_ucred, NULL); 166 if (error) 167 goto done2; 168 #endif 169 } 170 171 /* 172 * If accounting was previously enabled, kill the old space-watcher, 173 * close the file, and (if no new file was specified, leave). 174 */ 175 176 /* 177 * XXX arr: Should not hold lock over vnode operation. 178 */ 179 180 mtx_lock(&acct_mtx); 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 } 190 if (uap->path == NULL) { 191 mtx_unlock(&acct_mtx); 192 goto done2; 193 } 194 195 /* 196 * Save the new accounting file vnode, and schedule the new 197 * free space watcher. 198 */ 199 acctp = nd.ni_vp; 200 acctcred = crhold(td->td_ucred); 201 acctflags = flags; 202 callout_init(&acctwatch_callout, 0); 203 mtx_unlock(&acct_mtx); 204 acctwatch(NULL); 205 done2: 206 mtx_unlock(&Giant); 207 return (error); 208 } 209 210 /* 211 * Write out process accounting information, on process exit. 212 * Data to be written out is specified in Leffler, et al. 213 * and are enumerated below. (They're also noted in the system 214 * "acct.h" header file.) 215 */ 216 217 int 218 acct_process(td) 219 struct thread *td; 220 { 221 struct proc *p = td->td_proc; 222 struct acct acct; 223 struct rusage *r; 224 struct timeval ut, st, tmp; 225 int t, ret; 226 struct vnode *vp; 227 struct ucred *uc; 228 229 mtx_lock(&acct_mtx); 230 231 /* If accounting isn't enabled, don't bother */ 232 vp = acctp; 233 if (vp == NULLVP) { 234 mtx_unlock(&acct_mtx); 235 return (0); 236 } 237 238 /* 239 * Get process accounting information. 240 */ 241 242 /* (1) The name of the command that ran */ 243 bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm); 244 245 /* (2) The amount of user and system time that was used */ 246 mtx_lock_spin(&sched_lock); 247 calcru(p, &ut, &st, NULL); 248 mtx_unlock_spin(&sched_lock); 249 acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec); 250 acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec); 251 252 /* (3) The elapsed time the command ran (and its starting time) */ 253 acct.ac_btime = p->p_stats->p_start.tv_sec; 254 microtime(&tmp); 255 timevalsub(&tmp, &p->p_stats->p_start); 256 acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec); 257 258 /* (4) The average amount of memory used */ 259 r = &p->p_stats->p_ru; 260 tmp = ut; 261 timevaladd(&tmp, &st); 262 t = tmp.tv_sec * hz + tmp.tv_usec / tick; 263 if (t) 264 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t; 265 else 266 acct.ac_mem = 0; 267 268 /* (5) The number of disk I/O operations done */ 269 acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0); 270 271 /* (6) The UID and GID of the process */ 272 acct.ac_uid = p->p_ucred->cr_ruid; 273 acct.ac_gid = p->p_ucred->cr_rgid; 274 275 /* (7) The terminal from which the process was started */ 276 PROC_LOCK(p); 277 SESS_LOCK(p->p_session); 278 if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp) 279 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev); 280 else 281 acct.ac_tty = NOUDEV; 282 SESS_UNLOCK(p->p_session); 283 PROC_UNLOCK(p); 284 285 /* (8) The boolean flags that tell how the process terminated, etc. */ 286 acct.ac_flag = p->p_acflag; 287 288 /* 289 * Write the accounting information to the file. 290 */ 291 uc = crhold(acctcred); 292 vref(vp); 293 mtx_unlock(&acct_mtx); 294 295 /* 296 * Eliminate any file size rlimit. 297 */ 298 if (p->p_limit->p_refcnt > 1 && 299 (p->p_limit->p_lflags & PL_SHAREMOD) == 0) { 300 p->p_limit->p_refcnt--; 301 p->p_limit = limcopy(p->p_limit); 302 } 303 p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY; 304 305 VOP_LEASE(vp, td, uc, LEASE_WRITE); 306 ret = vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct), 307 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, uc, NOCRED, 308 (int *)0, td); 309 vrele(vp); 310 crfree(uc); 311 return (ret); 312 } 313 314 /* 315 * Encode_comp_t converts from ticks in seconds and microseconds 316 * to ticks in 1/AHZ seconds. The encoding is described in 317 * Leffler, et al., on page 63. 318 */ 319 320 #define MANTSIZE 13 /* 13 bit mantissa. */ 321 #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */ 322 #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */ 323 324 static comp_t 325 encode_comp_t(s, us) 326 u_long s, us; 327 { 328 int exp, rnd; 329 330 exp = 0; 331 rnd = 0; 332 s *= AHZ; 333 s += us / (1000000 / AHZ); /* Maximize precision. */ 334 335 while (s > MAXFRACT) { 336 rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */ 337 s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */ 338 exp++; 339 } 340 341 /* If we need to round up, do it (and handle overflow correctly). */ 342 if (rnd && (++s > MAXFRACT)) { 343 s >>= EXPSIZE; 344 exp++; 345 } 346 347 /* Clean it up and polish it off. */ 348 exp <<= MANTSIZE; /* Shift the exponent into place */ 349 exp += s; /* and add on the mantissa. */ 350 return (exp); 351 } 352 353 /* 354 * Periodically check the filesystem to see if accounting 355 * should be turned on or off. Beware the case where the vnode 356 * has been vgone()'d out from underneath us, e.g. when the file 357 * system containing the accounting file has been forcibly unmounted. 358 */ 359 /* ARGSUSED */ 360 static void 361 acctwatch(a) 362 void *a; 363 { 364 struct statfs sb; 365 366 mtx_lock(&acct_mtx); 367 368 /* 369 * XXX arr: Need to fix the issue of holding acct_mtx over 370 * the below vnode operations. 371 */ 372 373 if (savacctp != NULLVP) { 374 if (savacctp->v_type == VBAD) { 375 (void) vn_close(savacctp, savacctflags, savacctcred, 376 NULL); 377 savacctp = NULLVP; 378 savacctcred = NOCRED; 379 mtx_unlock(&acct_mtx); 380 return; 381 } 382 (void)VFS_STATFS(savacctp->v_mount, &sb, (struct thread *)0); 383 if (sb.f_bavail > acctresume * sb.f_blocks / 100) { 384 acctp = savacctp; 385 acctcred = savacctcred; 386 acctflags = savacctflags; 387 savacctp = NULLVP; 388 savacctcred = NOCRED; 389 log(LOG_NOTICE, "Accounting resumed\n"); 390 } 391 } else { 392 if (acctp == NULLVP) { 393 mtx_unlock(&acct_mtx); 394 return; 395 } 396 if (acctp->v_type == VBAD) { 397 (void) vn_close(acctp, acctflags, acctcred, NULL); 398 acctp = NULLVP; 399 crfree(acctcred); 400 acctcred = NOCRED; 401 mtx_unlock(&acct_mtx); 402 return; 403 } 404 (void)VFS_STATFS(acctp->v_mount, &sb, (struct thread *)0); 405 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) { 406 savacctp = acctp; 407 savacctflags = acctflags; 408 savacctcred = acctcred; 409 acctp = NULLVP; 410 acctcred = NOCRED; 411 log(LOG_NOTICE, "Accounting suspended\n"); 412 } 413 } 414 callout_reset(&acctwatch_callout, acctchkfreq * hz, acctwatch, NULL); 415 mtx_unlock(&acct_mtx); 416 }
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