kern_acct.c revision 167389
1/*- 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * Copyright (c) 2005 Robert N. M. Watson 6 * All rights reserved. 7 * 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * Copyright (c) 1994 Christopher G. Demetriou 38 * 39 * Redistribution and use in source and binary forms, with or without 40 * modification, are permitted provided that the following conditions 41 * are met: 42 * 1. Redistributions of source code must retain the above copyright 43 * notice, this list of conditions and the following disclaimer. 44 * 2. Redistributions in binary form must reproduce the above copyright 45 * notice, this list of conditions and the following disclaimer in the 46 * documentation and/or other materials provided with the distribution. 47 * 3. All advertising materials mentioning features or use of this software 48 * must display the following acknowledgement: 49 * This product includes software developed by the University of 50 * California, Berkeley and its contributors. 51 * 4. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * @(#)kern_acct.c 8.1 (Berkeley) 6/14/93 68 */ 69 70#include <sys/cdefs.h> 71__FBSDID("$FreeBSD: head/sys/kern/kern_acct.c 167389 2007-03-09 23:29:31Z jhb $"); 72 73#include "opt_mac.h" 74 75#include <sys/param.h> 76#include <sys/systm.h> 77#include <sys/acct.h> 78#include <sys/fcntl.h> 79#include <sys/kernel.h> 80#include <sys/kthread.h> 81#include <sys/lock.h> 82#include <sys/mount.h> 83#include <sys/mutex.h> 84#include <sys/namei.h> 85#include <sys/priv.h> 86#include <sys/proc.h> 87#include <sys/resourcevar.h> 88#include <sys/sched.h> 89#include <sys/sx.h> 90#include <sys/sysctl.h> 91#include <sys/sysent.h> 92#include <sys/syslog.h> 93#include <sys/sysproto.h> 94#include <sys/tty.h> 95#include <sys/vnode.h> 96 97#include <security/mac/mac_framework.h> 98 99/* 100 * The routines implemented in this file are described in: 101 * Leffler, et al.: The Design and Implementation of the 4.3BSD 102 * UNIX Operating System (Addison Welley, 1989) 103 * on pages 62-63. 104 * 105 * Arguably, to simplify accounting operations, this mechanism should 106 * be replaced by one in which an accounting log file (similar to /dev/klog) 107 * is read by a user process, etc. However, that has its own problems. 108 */ 109 110/* 111 * Internal accounting functions. 112 * The former's operation is described in Leffler, et al., and the latter 113 * was provided by UCB with the 4.4BSD-Lite release 114 */ 115static comp_t encode_comp_t(u_long, u_long); 116static void acctwatch(void); 117static void acct_thread(void *); 118static int acct_disable(struct thread *); 119 120/* 121 * Accounting vnode pointer, saved vnode pointer, and flags for each. 122 * acct_sx protects against changes to the active vnode and credentials 123 * while accounting records are being committed to disk. 124 */ 125static int acct_configured; 126static int acct_suspended; 127static struct vnode *acct_vp; 128static struct ucred *acct_cred; 129static int acct_flags; 130static struct sx acct_sx; 131 132SX_SYSINIT(acct, &acct_sx, "acct_sx"); 133 134/* 135 * State of the accounting kthread. 136 */ 137static int acct_state; 138 139#define ACCT_RUNNING 1 /* Accounting kthread is running. */ 140#define ACCT_EXITREQ 2 /* Accounting kthread should exit. */ 141 142/* 143 * Values associated with enabling and disabling accounting 144 */ 145static int acctsuspend = 2; /* stop accounting when < 2% free space left */ 146SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW, 147 &acctsuspend, 0, "percentage of free disk space below which accounting stops"); 148 149static int acctresume = 4; /* resume when free space risen to > 4% */ 150SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW, 151 &acctresume, 0, "percentage of free disk space above which accounting resumes"); 152 153static int acctchkfreq = 15; /* frequency (in seconds) to check space */ 154 155static int 156sysctl_acct_chkfreq(SYSCTL_HANDLER_ARGS) 157{ 158 int error, value; 159 160 /* Write out the old value. */ 161 error = SYSCTL_OUT(req, &acctchkfreq, sizeof(int)); 162 if (error || req->newptr == NULL) 163 return (error); 164 165 /* Read in and verify the new value. */ 166 error = SYSCTL_IN(req, &value, sizeof(int)); 167 if (error) 168 return (error); 169 if (value <= 0) 170 return (EINVAL); 171 acctchkfreq = value; 172 return (0); 173} 174SYSCTL_PROC(_kern, OID_AUTO, acct_chkfreq, CTLTYPE_INT|CTLFLAG_RW, 175 &acctchkfreq, 0, sysctl_acct_chkfreq, "I", 176 "frequency for checking the free space"); 177 178SYSCTL_INT(_kern, OID_AUTO, acct_configured, CTLFLAG_RD, &acct_configured, 0, 179 "Accounting configured or not"); 180 181SYSCTL_INT(_kern, OID_AUTO, acct_suspended, CTLFLAG_RD, &acct_suspended, 0, 182 "Accounting suspended or not"); 183 184/* 185 * Accounting system call. Written based on the specification and previous 186 * implementation done by Mark Tinguely. 187 */ 188int 189acct(struct thread *td, struct acct_args *uap) 190{ 191 struct nameidata nd; 192 int error, flags, vfslocked; 193 194 error = priv_check(td, PRIV_ACCT); 195 if (error) 196 return (error); 197 198 /* 199 * If accounting is to be started to a file, open that file for 200 * appending and make sure it's a 'normal'. 201 */ 202 if (uap->path != NULL) { 203 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE | AUDITVNODE1, 204 UIO_USERSPACE, uap->path, td); 205 flags = FWRITE | O_APPEND; 206 error = vn_open(&nd, &flags, 0, -1); 207 if (error) 208 return (error); 209 vfslocked = NDHASGIANT(&nd); 210 NDFREE(&nd, NDF_ONLY_PNBUF); 211#ifdef MAC 212 error = mac_check_system_acct(td->td_ucred, nd.ni_vp); 213 if (error) { 214 VOP_UNLOCK(nd.ni_vp, 0, td); 215 vn_close(nd.ni_vp, flags, td->td_ucred, td); 216 VFS_UNLOCK_GIANT(vfslocked); 217 return (error); 218 } 219#endif 220 VOP_UNLOCK(nd.ni_vp, 0, td); 221 if (nd.ni_vp->v_type != VREG) { 222 vn_close(nd.ni_vp, flags, td->td_ucred, td); 223 VFS_UNLOCK_GIANT(vfslocked); 224 return (EACCES); 225 } 226 VFS_UNLOCK_GIANT(vfslocked); 227#ifdef MAC 228 } else { 229 error = mac_check_system_acct(td->td_ucred, NULL); 230 if (error) 231 return (error); 232#endif 233 } 234 235 /* 236 * Disallow concurrent access to the accounting vnode while we swap 237 * it out, in order to prevent access after close. 238 */ 239 sx_xlock(&acct_sx); 240 241 /* 242 * If accounting was previously enabled, kill the old space-watcher, 243 * close the file, and (if no new file was specified, leave). Reset 244 * the suspended state regardless of whether accounting remains 245 * enabled. 246 */ 247 acct_suspended = 0; 248 if (acct_vp != NULL) { 249 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 250 error = acct_disable(td); 251 VFS_UNLOCK_GIANT(vfslocked); 252 } 253 if (uap->path == NULL) { 254 if (acct_state & ACCT_RUNNING) { 255 acct_state |= ACCT_EXITREQ; 256 wakeup(&acct_state); 257 } 258 sx_xunlock(&acct_sx); 259 return (error); 260 } 261 262 /* 263 * Save the new accounting file vnode, and schedule the new 264 * free space watcher. 265 */ 266 acct_vp = nd.ni_vp; 267 acct_cred = crhold(td->td_ucred); 268 acct_flags = flags; 269 if (acct_state & ACCT_RUNNING) 270 acct_state &= ~ACCT_EXITREQ; 271 else { 272 /* 273 * Try to start up an accounting kthread. We may start more 274 * than one, but if so the extras will commit suicide as 275 * soon as they start up. 276 */ 277 error = kthread_create(acct_thread, NULL, NULL, 0, 0, 278 "accounting"); 279 if (error) { 280 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 281 (void) vn_close(acct_vp, acct_flags, acct_cred, td); 282 VFS_UNLOCK_GIANT(vfslocked); 283 crfree(acct_cred); 284 acct_configured = 0; 285 acct_vp = NULL; 286 acct_cred = NULL; 287 acct_flags = 0; 288 sx_xunlock(&acct_sx); 289 log(LOG_NOTICE, "Unable to start accounting thread\n"); 290 return (error); 291 } 292 } 293 acct_configured = 1; 294 sx_xunlock(&acct_sx); 295 log(LOG_NOTICE, "Accounting enabled\n"); 296 return (error); 297} 298 299/* 300 * Disable currently in-progress accounting by closing the vnode, dropping 301 * our reference to the credential, and clearing the vnode's flags. 302 */ 303static int 304acct_disable(struct thread *td) 305{ 306 int error; 307 308 sx_assert(&acct_sx, SX_XLOCKED); 309 error = vn_close(acct_vp, acct_flags, acct_cred, td); 310 crfree(acct_cred); 311 acct_configured = 0; 312 acct_vp = NULL; 313 acct_cred = NULL; 314 acct_flags = 0; 315 log(LOG_NOTICE, "Accounting disabled\n"); 316 return (error); 317} 318 319/* 320 * Write out process accounting information, on process exit. 321 * Data to be written out is specified in Leffler, et al. 322 * and are enumerated below. (They're also noted in the system 323 * "acct.h" header file.) 324 */ 325int 326acct_process(struct thread *td) 327{ 328 struct acct acct; 329 struct timeval ut, st, tmp; 330 struct plimit *newlim, *oldlim; 331 struct proc *p; 332 struct rusage *r; 333 int t, ret, vfslocked; 334 335 /* 336 * Lockless check of accounting condition before doing the hard 337 * work. 338 */ 339 if (acct_vp == NULL || acct_suspended) 340 return (0); 341 342 sx_slock(&acct_sx); 343 344 /* 345 * If accounting isn't enabled, don't bother. Have to check again 346 * once we own the lock in case we raced with disabling of accounting 347 * by another thread. 348 */ 349 if (acct_vp == NULL || acct_suspended) { 350 sx_sunlock(&acct_sx); 351 return (0); 352 } 353 354 p = td->td_proc; 355 356 /* 357 * Get process accounting information. 358 */ 359 360 PROC_LOCK(p); 361 /* (1) The name of the command that ran */ 362 bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm); 363 364 /* (2) The amount of user and system time that was used */ 365 calcru(p, &ut, &st); 366 acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec); 367 acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec); 368 369 /* (3) The elapsed time the command ran (and its starting time) */ 370 tmp = boottime; 371 timevaladd(&tmp, &p->p_stats->p_start); 372 acct.ac_btime = tmp.tv_sec; 373 microuptime(&tmp); 374 timevalsub(&tmp, &p->p_stats->p_start); 375 acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec); 376 377 /* (4) The average amount of memory used */ 378 r = &p->p_stats->p_ru; 379 tmp = ut; 380 timevaladd(&tmp, &st); 381 t = tmp.tv_sec * hz + tmp.tv_usec / tick; 382 if (t) 383 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t; 384 else 385 acct.ac_mem = 0; 386 387 /* (5) The number of disk I/O operations done */ 388 acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0); 389 390 /* (6) The UID and GID of the process */ 391 acct.ac_uid = p->p_ucred->cr_ruid; 392 acct.ac_gid = p->p_ucred->cr_rgid; 393 394 /* (7) The terminal from which the process was started */ 395 SESS_LOCK(p->p_session); 396 if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp) 397 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev); 398 else 399 acct.ac_tty = NODEV; 400 SESS_UNLOCK(p->p_session); 401 402 /* (8) The boolean flags that tell how the process terminated, etc. */ 403 acct.ac_flag = p->p_acflag; 404 PROC_UNLOCK(p); 405 406 /* 407 * Eliminate any file size rlimit. 408 */ 409 newlim = lim_alloc(); 410 PROC_LOCK(p); 411 oldlim = p->p_limit; 412 lim_copy(newlim, oldlim); 413 newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY; 414 p->p_limit = newlim; 415 PROC_UNLOCK(p); 416 lim_free(oldlim); 417 418 /* 419 * Write the accounting information to the file. 420 */ 421 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 422 VOP_LEASE(acct_vp, td, acct_cred, LEASE_WRITE); 423 ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct), 424 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED, 425 (int *)0, td); 426 VFS_UNLOCK_GIANT(vfslocked); 427 sx_sunlock(&acct_sx); 428 return (ret); 429} 430 431/* 432 * Encode_comp_t converts from ticks in seconds and microseconds 433 * to ticks in 1/AHZ seconds. The encoding is described in 434 * Leffler, et al., on page 63. 435 */ 436 437#define MANTSIZE 13 /* 13 bit mantissa. */ 438#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */ 439#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */ 440 441static comp_t 442encode_comp_t(u_long s, u_long us) 443{ 444 int exp, rnd; 445 446 exp = 0; 447 rnd = 0; 448 s *= AHZ; 449 s += us / (1000000 / AHZ); /* Maximize precision. */ 450 451 while (s > MAXFRACT) { 452 rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */ 453 s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */ 454 exp++; 455 } 456 457 /* If we need to round up, do it (and handle overflow correctly). */ 458 if (rnd && (++s > MAXFRACT)) { 459 s >>= EXPSIZE; 460 exp++; 461 } 462 463 /* Clean it up and polish it off. */ 464 exp <<= MANTSIZE; /* Shift the exponent into place */ 465 exp += s; /* and add on the mantissa. */ 466 return (exp); 467} 468 469/* 470 * Periodically check the filesystem to see if accounting 471 * should be turned on or off. Beware the case where the vnode 472 * has been vgone()'d out from underneath us, e.g. when the file 473 * system containing the accounting file has been forcibly unmounted. 474 */ 475/* ARGSUSED */ 476static void 477acctwatch(void) 478{ 479 struct statfs sb; 480 int vfslocked; 481 482 sx_assert(&acct_sx, SX_XLOCKED); 483 484 /* 485 * If accounting was disabled before our kthread was scheduled, 486 * then acct_vp might be NULL. If so, just ask our kthread to 487 * exit and return. 488 */ 489 if (acct_vp == NULL) { 490 acct_state |= ACCT_EXITREQ; 491 return; 492 } 493 494 /* 495 * If our vnode is no longer valid, tear it down and signal the 496 * accounting thread to die. 497 */ 498 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 499 if (acct_vp->v_type == VBAD) { 500 (void) acct_disable(NULL); 501 VFS_UNLOCK_GIANT(vfslocked); 502 acct_state |= ACCT_EXITREQ; 503 return; 504 } 505 506 /* 507 * Stopping here is better than continuing, maybe it will be VBAD 508 * next time around. 509 */ 510 if (VFS_STATFS(acct_vp->v_mount, &sb, curthread) < 0) { 511 VFS_UNLOCK_GIANT(vfslocked); 512 return; 513 } 514 VFS_UNLOCK_GIANT(vfslocked); 515 if (acct_suspended) { 516 if (sb.f_bavail > (int64_t)(acctresume * sb.f_blocks / 517 100)) { 518 acct_suspended = 0; 519 log(LOG_NOTICE, "Accounting resumed\n"); 520 } 521 } else { 522 if (sb.f_bavail <= (int64_t)(acctsuspend * sb.f_blocks / 523 100)) { 524 acct_suspended = 1; 525 log(LOG_NOTICE, "Accounting suspended\n"); 526 } 527 } 528} 529 530/* 531 * The main loop for the dedicated kernel thread that periodically calls 532 * acctwatch(). 533 */ 534static void 535acct_thread(void *dummy) 536{ 537 u_char pri; 538 539 /* This is a low-priority kernel thread. */ 540 pri = PRI_MAX_KERN; 541 mtx_lock_spin(&sched_lock); 542 sched_prio(curthread, pri); 543 mtx_unlock_spin(&sched_lock); 544 545 /* If another accounting kthread is already running, just die. */ 546 sx_xlock(&acct_sx); 547 if (acct_state & ACCT_RUNNING) { 548 sx_xunlock(&acct_sx); 549 kthread_exit(0); 550 } 551 acct_state |= ACCT_RUNNING; 552 553 /* Loop until we are asked to exit. */ 554 while (!(acct_state & ACCT_EXITREQ)) { 555 556 /* Perform our periodic checks. */ 557 acctwatch(); 558 559 /* 560 * We check this flag again before sleeping since the 561 * acctwatch() might have shut down accounting and asked us 562 * to exit. 563 */ 564 if (!(acct_state & ACCT_EXITREQ)) { 565 sx_sleep(&acct_state, &acct_sx, 0, "-", 566 acctchkfreq * hz); 567 } 568 } 569 570 /* 571 * Acknowledge the exit request and shutdown. We clear both the 572 * exit request and running flags. 573 */ 574 acct_state = 0; 575 sx_xunlock(&acct_sx); 576 kthread_exit(0); 577} 578