kern_acct.c revision 165896
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 165896 2007-01-08 20:35:13Z rwatson $"); 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 186 * previous implementation done by Mark Tinguely. 187 * 188 * MPSAFE 189 */ 190int 191acct(struct thread *td, struct acct_args *uap) 192{ 193 struct nameidata nd; 194 int error, flags, vfslocked; 195 196 error = priv_check(td, PRIV_ACCT); 197 if (error) 198 return (error); 199 200 /* 201 * If accounting is to be started to a file, open that file for 202 * appending and make sure it's a 'normal'. 203 */ 204 if (uap->path != NULL) { 205 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE | AUDITVNODE1, 206 UIO_USERSPACE, uap->path, td); 207 flags = FWRITE | O_APPEND; 208 error = vn_open(&nd, &flags, 0, -1); 209 if (error) 210 return (error); 211 vfslocked = NDHASGIANT(&nd); 212 NDFREE(&nd, NDF_ONLY_PNBUF); 213#ifdef MAC 214 error = mac_check_system_acct(td->td_ucred, nd.ni_vp); 215 if (error) { 216 VOP_UNLOCK(nd.ni_vp, 0, td); 217 vn_close(nd.ni_vp, flags, td->td_ucred, td); 218 VFS_UNLOCK_GIANT(vfslocked); 219 return (error); 220 } 221#endif 222 VOP_UNLOCK(nd.ni_vp, 0, td); 223 if (nd.ni_vp->v_type != VREG) { 224 vn_close(nd.ni_vp, flags, td->td_ucred, td); 225 VFS_UNLOCK_GIANT(vfslocked); 226 return (EACCES); 227 } 228 VFS_UNLOCK_GIANT(vfslocked); 229#ifdef MAC 230 } else { 231 error = mac_check_system_acct(td->td_ucred, NULL); 232 if (error) 233 return (error); 234#endif 235 } 236 237 /* 238 * Disallow concurrent access to the accounting vnode while we swap 239 * it out, in order to prevent access after close. 240 */ 241 sx_xlock(&acct_sx); 242 243 /* 244 * If accounting was previously enabled, kill the old space-watcher, 245 * close the file, and (if no new file was specified, leave). Reset 246 * the suspended state regardless of whether accounting remains 247 * enabled. 248 */ 249 acct_suspended = 0; 250 if (acct_vp != NULL) { 251 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 252 error = acct_disable(td); 253 VFS_UNLOCK_GIANT(vfslocked); 254 } 255 if (uap->path == NULL) { 256 if (acct_state & ACCT_RUNNING) { 257 acct_state |= ACCT_EXITREQ; 258 wakeup(&acct_state); 259 } 260 sx_xunlock(&acct_sx); 261 return (error); 262 } 263 264 /* 265 * Save the new accounting file vnode, and schedule the new 266 * free space watcher. 267 */ 268 acct_vp = nd.ni_vp; 269 acct_cred = crhold(td->td_ucred); 270 acct_flags = flags; 271 if (acct_state & ACCT_RUNNING) 272 acct_state &= ~ACCT_EXITREQ; 273 else { 274 /* 275 * Try to start up an accounting kthread. We may start more 276 * than one, but if so the extras will commit suicide as 277 * soon as they start up. 278 */ 279 error = kthread_create(acct_thread, NULL, NULL, 0, 0, 280 "accounting"); 281 if (error) { 282 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 283 (void) vn_close(acct_vp, acct_flags, acct_cred, td); 284 VFS_UNLOCK_GIANT(vfslocked); 285 crfree(acct_cred); 286 acct_configured = 0; 287 acct_vp = NULL; 288 acct_cred = NULL; 289 acct_flags = 0; 290 sx_xunlock(&acct_sx); 291 log(LOG_NOTICE, "Unable to start accounting thread\n"); 292 return (error); 293 } 294 } 295 acct_configured = 1; 296 sx_xunlock(&acct_sx); 297 log(LOG_NOTICE, "Accounting enabled\n"); 298 return (error); 299} 300 301/* 302 * Disable currently in-progress accounting by closing the vnode, dropping 303 * our reference to the credential, and clearing the vnode's flags. 304 */ 305static int 306acct_disable(struct thread *td) 307{ 308 int error; 309 310 sx_assert(&acct_sx, SX_XLOCKED); 311 error = vn_close(acct_vp, acct_flags, acct_cred, td); 312 crfree(acct_cred); 313 acct_configured = 0; 314 acct_vp = NULL; 315 acct_cred = NULL; 316 acct_flags = 0; 317 log(LOG_NOTICE, "Accounting disabled\n"); 318 return (error); 319} 320 321/* 322 * Write out process accounting information, on process exit. 323 * Data to be written out is specified in Leffler, et al. 324 * and are enumerated below. (They're also noted in the system 325 * "acct.h" header file.) 326 */ 327int 328acct_process(struct thread *td) 329{ 330 struct acct acct; 331 struct timeval ut, st, tmp; 332 struct plimit *newlim, *oldlim; 333 struct proc *p; 334 struct rusage *r; 335 int t, ret, vfslocked; 336 337 /* 338 * Lockless check of accounting condition before doing the hard 339 * work. 340 */ 341 if (acct_vp == NULL || acct_suspended) 342 return (0); 343 344 sx_slock(&acct_sx); 345 346 /* 347 * If accounting isn't enabled, don't bother. Have to check again 348 * once we own the lock in case we raced with disabling of accounting 349 * by another thread. 350 */ 351 if (acct_vp == NULL || acct_suspended) { 352 sx_sunlock(&acct_sx); 353 return (0); 354 } 355 356 p = td->td_proc; 357 358 /* 359 * Get process accounting information. 360 */ 361 362 PROC_LOCK(p); 363 /* (1) The name of the command that ran */ 364 bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm); 365 366 /* (2) The amount of user and system time that was used */ 367 calcru(p, &ut, &st); 368 acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec); 369 acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec); 370 371 /* (3) The elapsed time the command ran (and its starting time) */ 372 tmp = boottime; 373 timevaladd(&tmp, &p->p_stats->p_start); 374 acct.ac_btime = tmp.tv_sec; 375 microuptime(&tmp); 376 timevalsub(&tmp, &p->p_stats->p_start); 377 acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec); 378 379 /* (4) The average amount of memory used */ 380 r = &p->p_stats->p_ru; 381 tmp = ut; 382 timevaladd(&tmp, &st); 383 t = tmp.tv_sec * hz + tmp.tv_usec / tick; 384 if (t) 385 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t; 386 else 387 acct.ac_mem = 0; 388 389 /* (5) The number of disk I/O operations done */ 390 acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0); 391 392 /* (6) The UID and GID of the process */ 393 acct.ac_uid = p->p_ucred->cr_ruid; 394 acct.ac_gid = p->p_ucred->cr_rgid; 395 396 /* (7) The terminal from which the process was started */ 397 SESS_LOCK(p->p_session); 398 if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp) 399 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev); 400 else 401 acct.ac_tty = NODEV; 402 SESS_UNLOCK(p->p_session); 403 404 /* (8) The boolean flags that tell how the process terminated, etc. */ 405 acct.ac_flag = p->p_acflag; 406 PROC_UNLOCK(p); 407 408 /* 409 * Eliminate any file size rlimit. 410 */ 411 newlim = lim_alloc(); 412 PROC_LOCK(p); 413 oldlim = p->p_limit; 414 lim_copy(newlim, oldlim); 415 newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY; 416 p->p_limit = newlim; 417 PROC_UNLOCK(p); 418 lim_free(oldlim); 419 420 /* 421 * Write the accounting information to the file. 422 */ 423 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 424 VOP_LEASE(acct_vp, td, acct_cred, LEASE_WRITE); 425 ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct), 426 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED, 427 (int *)0, td); 428 VFS_UNLOCK_GIANT(vfslocked); 429 sx_sunlock(&acct_sx); 430 return (ret); 431} 432 433/* 434 * Encode_comp_t converts from ticks in seconds and microseconds 435 * to ticks in 1/AHZ seconds. The encoding is described in 436 * Leffler, et al., on page 63. 437 */ 438 439#define MANTSIZE 13 /* 13 bit mantissa. */ 440#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */ 441#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */ 442 443static comp_t 444encode_comp_t(u_long s, u_long us) 445{ 446 int exp, rnd; 447 448 exp = 0; 449 rnd = 0; 450 s *= AHZ; 451 s += us / (1000000 / AHZ); /* Maximize precision. */ 452 453 while (s > MAXFRACT) { 454 rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */ 455 s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */ 456 exp++; 457 } 458 459 /* If we need to round up, do it (and handle overflow correctly). */ 460 if (rnd && (++s > MAXFRACT)) { 461 s >>= EXPSIZE; 462 exp++; 463 } 464 465 /* Clean it up and polish it off. */ 466 exp <<= MANTSIZE; /* Shift the exponent into place */ 467 exp += s; /* and add on the mantissa. */ 468 return (exp); 469} 470 471/* 472 * Periodically check the filesystem to see if accounting 473 * should be turned on or off. Beware the case where the vnode 474 * has been vgone()'d out from underneath us, e.g. when the file 475 * system containing the accounting file has been forcibly unmounted. 476 */ 477/* ARGSUSED */ 478static void 479acctwatch(void) 480{ 481 struct statfs sb; 482 int vfslocked; 483 484 sx_assert(&acct_sx, SX_XLOCKED); 485 486 /* 487 * If accounting was disabled before our kthread was scheduled, 488 * then acct_vp might be NULL. If so, just ask our kthread to 489 * exit and return. 490 */ 491 if (acct_vp == NULL) { 492 acct_state |= ACCT_EXITREQ; 493 return; 494 } 495 496 /* 497 * If our vnode is no longer valid, tear it down and signal the 498 * accounting thread to die. 499 */ 500 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 501 if (acct_vp->v_type == VBAD) { 502 (void) acct_disable(NULL); 503 VFS_UNLOCK_GIANT(vfslocked); 504 acct_state |= ACCT_EXITREQ; 505 return; 506 } 507 508 /* 509 * Stopping here is better than continuing, maybe it will be VBAD 510 * next time around. 511 */ 512 if (VFS_STATFS(acct_vp->v_mount, &sb, curthread) < 0) { 513 VFS_UNLOCK_GIANT(vfslocked); 514 return; 515 } 516 VFS_UNLOCK_GIANT(vfslocked); 517 if (acct_suspended) { 518 if (sb.f_bavail > (int64_t)(acctresume * sb.f_blocks / 519 100)) { 520 acct_suspended = 0; 521 log(LOG_NOTICE, "Accounting resumed\n"); 522 } 523 } else { 524 if (sb.f_bavail <= (int64_t)(acctsuspend * sb.f_blocks / 525 100)) { 526 acct_suspended = 1; 527 log(LOG_NOTICE, "Accounting suspended\n"); 528 } 529 } 530} 531 532/* 533 * The main loop for the dedicated kernel thread that periodically calls 534 * acctwatch(). 535 */ 536static void 537acct_thread(void *dummy) 538{ 539 u_char pri; 540 541 /* This is a low-priority kernel thread. */ 542 pri = PRI_MAX_KERN; 543 mtx_lock_spin(&sched_lock); 544 sched_prio(curthread, pri); 545 mtx_unlock_spin(&sched_lock); 546 547 /* If another accounting kthread is already running, just die. */ 548 sx_xlock(&acct_sx); 549 if (acct_state & ACCT_RUNNING) { 550 sx_xunlock(&acct_sx); 551 kthread_exit(0); 552 } 553 acct_state |= ACCT_RUNNING; 554 555 /* Loop until we are asked to exit. */ 556 while (!(acct_state & ACCT_EXITREQ)) { 557 558 /* Perform our periodic checks. */ 559 acctwatch(); 560 561 /* 562 * We check this flag again before sleeping since the 563 * acctwatch() might have shut down accounting and asked us 564 * to exit. 565 */ 566 if (!(acct_state & ACCT_EXITREQ)) { 567 sx_xunlock(&acct_sx); 568 tsleep(&acct_state, pri, "-", acctchkfreq * hz); 569 sx_xlock(&acct_sx); 570 } 571 } 572 573 /* 574 * Acknowledge the exit request and shutdown. We clear both the 575 * exit request and running flags. 576 */ 577 acct_state = 0; 578 sx_xunlock(&acct_sx); 579 kthread_exit(0); 580} 581