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