FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_acct.c
1 /* $OpenBSD: kern_acct.c,v 1.47 2022/08/14 01:58:27 jsg Exp $ */
2 /* $NetBSD: kern_acct.c,v 1.42 1996/02/04 02:15:12 christos Exp $ */
3
4 /*-
5 * Copyright (c) 1994 Christopher G. Demetriou
6 * Copyright (c) 1982, 1986, 1989, 1993
7 * The Regents of the University of California. All rights reserved.
8 * (c) UNIX System Laboratories, Inc.
9 * All or some portions of this file are derived from material licensed
10 * to the University of California by American Telephone and Telegraph
11 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
12 * the permission of UNIX System Laboratories, Inc.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
39 */
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/proc.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/namei.h>
50 #include <sys/errno.h>
51 #include <sys/acct.h>
52 #include <sys/resourcevar.h>
53 #include <sys/tty.h>
54 #include <sys/kthread.h>
55 #include <sys/rwlock.h>
56
57 #include <sys/syscallargs.h>
58
59 /*
60 * The routines implemented in this file are described in:
61 * Leffler, et al.: The Design and Implementation of the 4.3BSD
62 * UNIX Operating System (Addison Welley, 1989)
63 * on pages 62-63.
64 *
65 * Arguably, to simplify accounting operations, this mechanism should
66 * be replaced by one in which an accounting log file (similar to /dev/klog)
67 * is read by a user process, etc. However, that has its own problems.
68 */
69
70 /*
71 * Internal accounting functions.
72 */
73 comp_t encode_comp_t(u_long, u_long);
74 int acct_start(void);
75 void acct_thread(void *);
76 void acct_shutdown(void);
77
78 /*
79 * Accounting vnode pointer, and saved vnode pointer.
80 */
81 struct vnode *acctp;
82 struct vnode *savacctp;
83
84 /*
85 * Lock protecting acctp and savacctp.
86 */
87 struct rwlock acct_lock = RWLOCK_INITIALIZER("acctlk");
88
89 /*
90 * Values associated with enabling and disabling accounting
91 */
92 int acctsuspend = 2; /* stop accounting when < 2% free space left */
93 int acctresume = 4; /* resume when free space risen to > 4% */
94 int acctrate = 15; /* delay (in seconds) between space checks */
95
96 struct proc *acct_proc;
97
98 /*
99 * Accounting system call. Written based on the specification and
100 * previous implementation done by Mark Tinguely.
101 */
102 int
103 sys_acct(struct proc *p, void *v, register_t *retval)
104 {
105 struct sys_acct_args /* {
106 syscallarg(const char *) path;
107 } */ *uap = v;
108 struct nameidata nd;
109 int error;
110
111 /* Make sure that the caller is root. */
112 if ((error = suser(p)) != 0)
113 return (error);
114
115 /*
116 * If accounting is to be started to a file, open that file for
117 * writing and make sure it's 'normal'.
118 */
119 if (SCARG(uap, path) != NULL) {
120 NDINIT(&nd, 0, 0, UIO_USERSPACE, SCARG(uap, path), p);
121 if ((error = vn_open(&nd, FWRITE|O_APPEND, 0)) != 0)
122 return (error);
123 VOP_UNLOCK(nd.ni_vp);
124 if (nd.ni_vp->v_type != VREG) {
125 vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
126 return (EACCES);
127 }
128 }
129
130 rw_enter_write(&acct_lock);
131
132 /*
133 * If accounting was previously enabled, kill the old space-watcher,
134 * close the file, and (if no new file was specified, leave).
135 */
136 if (acctp != NULL || savacctp != NULL) {
137 wakeup(&acct_proc);
138 (void)vn_close((acctp != NULL ? acctp : savacctp), FWRITE,
139 p->p_ucred, p);
140 acctp = savacctp = NULL;
141 }
142 if (SCARG(uap, path) == NULL)
143 goto out;
144
145 /*
146 * Save the new accounting file vnode, and schedule the new
147 * free space watcher.
148 */
149 acctp = nd.ni_vp;
150 if ((error = acct_start()) != 0) {
151 acctp = NULL;
152 (void)vn_close(nd.ni_vp, FWRITE, p->p_ucred, p);
153 }
154
155 out:
156 rw_exit_write(&acct_lock);
157 return (error);
158 }
159
160 /*
161 * Write out process accounting information, on process exit.
162 * Data to be written out is specified in Leffler, et al.
163 * and are enumerated below. (They're also noted in the system
164 * "acct.h" header file.)
165 */
166 int
167 acct_process(struct proc *p)
168 {
169 struct acct acct;
170 struct process *pr = p->p_p;
171 struct rusage *r;
172 struct timespec booted, elapsed, realstart, st, tmp, uptime, ut;
173 int t;
174 struct vnode *vp;
175 int error = 0;
176
177 /* If accounting isn't enabled, don't bother */
178 if (acctp == NULL)
179 return (0);
180
181 rw_enter_read(&acct_lock);
182
183 /*
184 * Check the vnode again in case accounting got disabled while waiting
185 * for the lock.
186 */
187 vp = acctp;
188 if (vp == NULL)
189 goto out;
190
191 /*
192 * Get process accounting information.
193 */
194
195 /* (1) The name of the command that ran */
196 memcpy(acct.ac_comm, pr->ps_comm, sizeof acct.ac_comm);
197
198 /* (2) The amount of user and system time that was used */
199 calctsru(&pr->ps_tu, &ut, &st, NULL);
200 acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_nsec);
201 acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_nsec);
202
203 /* (3) The elapsed time the command ran (and its starting time) */
204 nanouptime(&uptime);
205 nanoboottime(&booted);
206 timespecadd(&booted, &pr->ps_start, &realstart);
207 acct.ac_btime = realstart.tv_sec;
208 timespecsub(&uptime, &pr->ps_start, &elapsed);
209 acct.ac_etime = encode_comp_t(elapsed.tv_sec, elapsed.tv_nsec);
210
211 /* (4) The average amount of memory used */
212 r = &p->p_ru;
213 timespecadd(&ut, &st, &tmp);
214 t = tmp.tv_sec * hz + tmp.tv_nsec / (1000 * tick);
215 if (t)
216 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
217 else
218 acct.ac_mem = 0;
219
220 /* (5) The number of disk I/O operations done */
221 acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
222
223 /* (6) The UID and GID of the process */
224 acct.ac_uid = pr->ps_ucred->cr_ruid;
225 acct.ac_gid = pr->ps_ucred->cr_rgid;
226
227 /* (7) The terminal from which the process was started */
228 if ((pr->ps_flags & PS_CONTROLT) &&
229 pr->ps_pgrp->pg_session->s_ttyp)
230 acct.ac_tty = pr->ps_pgrp->pg_session->s_ttyp->t_dev;
231 else
232 acct.ac_tty = -1;
233
234 /* (8) The boolean flags that tell how process terminated or misbehaved. */
235 acct.ac_flag = pr->ps_acflag;
236
237 /* Extensions */
238 acct.ac_pid = pr->ps_pid;
239
240 /*
241 * Now, just write the accounting information to the file.
242 */
243 error = vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
244 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT|IO_NOLIMIT,
245 p->p_ucred, NULL, p);
246
247 out:
248 rw_exit_read(&acct_lock);
249 return (error);
250 }
251
252 /*
253 * Encode_comp_t converts from ticks in seconds and microseconds
254 * to ticks in 1/AHZ seconds. The encoding is described in
255 * Leffler, et al., on page 63.
256 */
257
258 #define MANTSIZE 13 /* 13 bit mantissa. */
259 #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
260 #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
261
262 comp_t
263 encode_comp_t(u_long s, u_long ns)
264 {
265 int exp, rnd;
266
267 exp = 0;
268 rnd = 0;
269 s *= AHZ;
270 s += ns / (1000000000 / AHZ); /* Maximize precision. */
271
272 while (s > MAXFRACT) {
273 rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
274 s >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
275 exp++;
276 }
277
278 /* If we need to round up, do it (and handle overflow correctly). */
279 if (rnd && (++s > MAXFRACT)) {
280 s >>= EXPSIZE;
281 exp++;
282 }
283
284 /* Clean it up and polish it off. */
285 exp <<= MANTSIZE; /* Shift the exponent into place */
286 exp += s; /* and add on the mantissa. */
287 return (exp);
288 }
289
290 int
291 acct_start(void)
292 {
293 /* Already running. */
294 if (acct_proc != NULL)
295 return (0);
296
297 return (kthread_create(acct_thread, NULL, &acct_proc, "acct"));
298 }
299
300 /*
301 * Periodically check the file system to see if accounting
302 * should be turned on or off. Beware the case where the vnode
303 * has been vgone()'d out from underneath us, e.g. when the file
304 * system containing the accounting file has been forcibly unmounted.
305 */
306 void
307 acct_thread(void *arg)
308 {
309 struct statfs sb;
310 struct proc *p = curproc;
311
312 rw_enter_write(&acct_lock);
313 for (;;) {
314 if (savacctp != NULL) {
315 if (savacctp->v_type == VBAD) {
316 (void) vn_close(savacctp, FWRITE, NOCRED, p);
317 savacctp = NULL;
318 break;
319 }
320 (void)VFS_STATFS(savacctp->v_mount, &sb, NULL);
321 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
322 acctp = savacctp;
323 savacctp = NULL;
324 log(LOG_NOTICE, "Accounting resumed\n");
325 }
326 } else if (acctp != NULL) {
327 if (acctp->v_type == VBAD) {
328 (void) vn_close(acctp, FWRITE, NOCRED, p);
329 acctp = NULL;
330 break;
331 }
332 (void)VFS_STATFS(acctp->v_mount, &sb, NULL);
333 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
334 savacctp = acctp;
335 acctp = NULL;
336 log(LOG_NOTICE, "Accounting suspended\n");
337 }
338 } else {
339 break;
340 }
341 rwsleep_nsec(&acct_proc, &acct_lock, PPAUSE, "acct",
342 SEC_TO_NSEC(acctrate));
343 }
344 acct_proc = NULL;
345 rw_exit_write(&acct_lock);
346 kthread_exit(0);
347 }
348
349 void
350 acct_shutdown(void)
351 {
352
353 struct proc *p = curproc;
354
355 rw_enter_write(&acct_lock);
356 if (acctp != NULL || savacctp != NULL) {
357 vn_close((acctp != NULL ? acctp : savacctp), FWRITE,
358 NOCRED, p);
359 acctp = savacctp = NULL;
360 }
361 rw_exit_write(&acct_lock);
362 }
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