Line data Source code
1 : /*
2 : * linux/kernel/acct.c
3 : *
4 : * BSD Process Accounting for Linux
5 : *
6 : * Author: Marco van Wieringen <mvw@planets.elm.net>
7 : *
8 : * Some code based on ideas and code from:
9 : * Thomas K. Dyas <tdyas@eden.rutgers.edu>
10 : *
11 : * This file implements BSD-style process accounting. Whenever any
12 : * process exits, an accounting record of type "struct acct" is
13 : * written to the file specified with the acct() system call. It is
14 : * up to user-level programs to do useful things with the accounting
15 : * log. The kernel just provides the raw accounting information.
16 : *
17 : * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
18 : *
19 : * Plugged two leaks. 1) It didn't return acct_file into the free_filps if
20 : * the file happened to be read-only. 2) If the accounting was suspended
21 : * due to the lack of space it happily allowed to reopen it and completely
22 : * lost the old acct_file. 3/10/98, Al Viro.
23 : *
24 : * Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
25 : * XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
26 : *
27 : * Fixed a nasty interaction with with sys_umount(). If the accointing
28 : * was suspeneded we failed to stop it on umount(). Messy.
29 : * Another one: remount to readonly didn't stop accounting.
30 : * Question: what should we do if we have CAP_SYS_ADMIN but not
31 : * CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
32 : * unless we are messing with the root. In that case we are getting a
33 : * real mess with do_remount_sb(). 9/11/98, AV.
34 : *
35 : * Fixed a bunch of races (and pair of leaks). Probably not the best way,
36 : * but this one obviously doesn't introduce deadlocks. Later. BTW, found
37 : * one race (and leak) in BSD implementation.
38 : * OK, that's better. ANOTHER race and leak in BSD variant. There always
39 : * is one more bug... 10/11/98, AV.
40 : *
41 : * Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
42 : * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
43 : * a struct file opened for write. Fixed. 2/6/2000, AV.
44 : */
45 :
46 : #include <linux/mm.h>
47 : #include <linux/slab.h>
48 : #include <linux/acct.h>
49 : #include <linux/capability.h>
50 : #include <linux/file.h>
51 : #include <linux/tty.h>
52 : #include <linux/security.h>
53 : #include <linux/vfs.h>
54 : #include <linux/jiffies.h>
55 : #include <linux/times.h>
56 : #include <linux/syscalls.h>
57 : #include <linux/mount.h>
58 : #include <linux/uaccess.h>
59 : #include <asm/div64.h>
60 : #include <linux/blkdev.h> /* sector_div */
61 : #include <linux/pid_namespace.h>
62 : #include <linux/fs_pin.h>
63 :
64 : /*
65 : * These constants control the amount of freespace that suspend and
66 : * resume the process accounting system, and the time delay between
67 : * each check.
68 : * Turned into sysctl-controllable parameters. AV, 12/11/98
69 : */
70 :
71 : int acct_parm[3] = {4, 2, 30};
72 : #define RESUME (acct_parm[0]) /* >foo% free space - resume */
73 : #define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
74 : #define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
75 :
76 : /*
77 : * External references and all of the globals.
78 : */
79 : static void do_acct_process(struct bsd_acct_struct *acct);
80 :
81 : struct bsd_acct_struct {
82 : struct fs_pin pin;
83 : struct mutex lock;
84 : int active;
85 : unsigned long needcheck;
86 : struct file *file;
87 : struct pid_namespace *ns;
88 : struct work_struct work;
89 : struct completion done;
90 : };
91 :
92 : /*
93 : * Check the amount of free space and suspend/resume accordingly.
94 : */
95 0 : static int check_free_space(struct bsd_acct_struct *acct)
96 : {
97 : struct kstatfs sbuf;
98 :
99 0 : if (time_is_before_jiffies(acct->needcheck))
100 : goto out;
101 :
102 : /* May block */
103 0 : if (vfs_statfs(&acct->file->f_path, &sbuf))
104 : goto out;
105 :
106 0 : if (acct->active) {
107 0 : u64 suspend = sbuf.f_blocks * SUSPEND;
108 0 : do_div(suspend, 100);
109 0 : if (sbuf.f_bavail <= suspend) {
110 0 : acct->active = 0;
111 0 : pr_info("Process accounting paused\n");
112 : }
113 : } else {
114 0 : u64 resume = sbuf.f_blocks * RESUME;
115 0 : do_div(resume, 100);
116 0 : if (sbuf.f_bavail >= resume) {
117 0 : acct->active = 1;
118 0 : pr_info("Process accounting resumed\n");
119 : }
120 : }
121 :
122 0 : acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
123 : out:
124 0 : return acct->active;
125 : }
126 :
127 0 : static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
128 : {
129 : struct bsd_acct_struct *res;
130 : again:
131 0 : smp_rmb();
132 : rcu_read_lock();
133 0 : res = ACCESS_ONCE(ns->bacct);
134 0 : if (!res) {
135 : rcu_read_unlock();
136 0 : return NULL;
137 : }
138 0 : if (!atomic_long_inc_not_zero(&res->pin.count)) {
139 : rcu_read_unlock();
140 0 : cpu_relax();
141 0 : goto again;
142 : }
143 : rcu_read_unlock();
144 0 : mutex_lock(&res->lock);
145 0 : if (!res->ns) {
146 0 : mutex_unlock(&res->lock);
147 0 : pin_put(&res->pin);
148 0 : goto again;
149 : }
150 : return res;
151 : }
152 :
153 0 : static void close_work(struct work_struct *work)
154 : {
155 : struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
156 0 : struct file *file = acct->file;
157 0 : if (file->f_op->flush)
158 0 : file->f_op->flush(file, NULL);
159 0 : __fput_sync(file);
160 0 : complete(&acct->done);
161 0 : }
162 :
163 0 : static void acct_kill(struct bsd_acct_struct *acct,
164 : struct bsd_acct_struct *new)
165 : {
166 0 : if (acct) {
167 0 : struct pid_namespace *ns = acct->ns;
168 0 : do_acct_process(acct);
169 0 : INIT_WORK(&acct->work, close_work);
170 : init_completion(&acct->done);
171 0 : schedule_work(&acct->work);
172 0 : wait_for_completion(&acct->done);
173 0 : pin_remove(&acct->pin);
174 0 : ns->bacct = new;
175 0 : acct->ns = NULL;
176 : atomic_long_dec(&acct->pin.count);
177 0 : mutex_unlock(&acct->lock);
178 0 : pin_put(&acct->pin);
179 : }
180 0 : }
181 :
182 0 : static void acct_pin_kill(struct fs_pin *pin)
183 : {
184 : struct bsd_acct_struct *acct;
185 : acct = container_of(pin, struct bsd_acct_struct, pin);
186 0 : mutex_lock(&acct->lock);
187 0 : if (!acct->ns) {
188 0 : mutex_unlock(&acct->lock);
189 0 : pin_put(pin);
190 : acct = NULL;
191 : }
192 0 : acct_kill(acct, NULL);
193 0 : }
194 :
195 0 : static int acct_on(struct filename *pathname)
196 : {
197 0 : struct file *file;
198 : struct vfsmount *mnt, *internal;
199 0 : struct pid_namespace *ns = task_active_pid_ns(current);
200 : struct bsd_acct_struct *acct, *old;
201 : int err;
202 :
203 : acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
204 0 : if (!acct)
205 : return -ENOMEM;
206 :
207 : /* Difference from BSD - they don't do O_APPEND */
208 0 : file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
209 0 : if (IS_ERR(file)) {
210 0 : kfree(acct);
211 0 : return PTR_ERR(file);
212 : }
213 :
214 0 : if (!S_ISREG(file_inode(file)->i_mode)) {
215 0 : kfree(acct);
216 0 : filp_close(file, NULL);
217 0 : return -EACCES;
218 : }
219 :
220 0 : if (!file->f_op->write) {
221 0 : kfree(acct);
222 0 : filp_close(file, NULL);
223 0 : return -EIO;
224 : }
225 0 : internal = mnt_clone_internal(&file->f_path);
226 0 : if (IS_ERR(internal)) {
227 0 : kfree(acct);
228 0 : filp_close(file, NULL);
229 0 : return PTR_ERR(internal);
230 : }
231 0 : err = mnt_want_write(internal);
232 0 : if (err) {
233 0 : mntput(internal);
234 0 : kfree(acct);
235 0 : filp_close(file, NULL);
236 0 : return err;
237 : }
238 0 : mnt = file->f_path.mnt;
239 0 : file->f_path.mnt = internal;
240 :
241 : atomic_long_set(&acct->pin.count, 1);
242 0 : acct->pin.kill = acct_pin_kill;
243 0 : acct->file = file;
244 0 : acct->needcheck = jiffies;
245 0 : acct->ns = ns;
246 0 : mutex_init(&acct->lock);
247 0 : mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */
248 0 : pin_insert(&acct->pin, mnt);
249 :
250 0 : old = acct_get(ns);
251 0 : if (old)
252 0 : acct_kill(old, acct);
253 : else
254 0 : ns->bacct = acct;
255 0 : mutex_unlock(&acct->lock);
256 0 : mnt_drop_write(mnt);
257 0 : mntput(mnt);
258 0 : return 0;
259 : }
260 :
261 : static DEFINE_MUTEX(acct_on_mutex);
262 :
263 : /**
264 : * sys_acct - enable/disable process accounting
265 : * @name: file name for accounting records or NULL to shutdown accounting
266 : *
267 : * Returns 0 for success or negative errno values for failure.
268 : *
269 : * sys_acct() is the only system call needed to implement process
270 : * accounting. It takes the name of the file where accounting records
271 : * should be written. If the filename is NULL, accounting will be
272 : * shutdown.
273 : */
274 0 : SYSCALL_DEFINE1(acct, const char __user *, name)
275 : {
276 : int error = 0;
277 :
278 0 : if (!capable(CAP_SYS_PACCT))
279 : return -EPERM;
280 :
281 0 : if (name) {
282 0 : struct filename *tmp = getname(name);
283 :
284 0 : if (IS_ERR(tmp))
285 : return PTR_ERR(tmp);
286 0 : mutex_lock(&acct_on_mutex);
287 0 : error = acct_on(tmp);
288 0 : mutex_unlock(&acct_on_mutex);
289 0 : putname(tmp);
290 : } else {
291 0 : acct_kill(acct_get(task_active_pid_ns(current)), NULL);
292 : }
293 :
294 : return error;
295 : }
296 :
297 0 : void acct_exit_ns(struct pid_namespace *ns)
298 : {
299 0 : acct_kill(acct_get(ns), NULL);
300 0 : }
301 :
302 : /*
303 : * encode an unsigned long into a comp_t
304 : *
305 : * This routine has been adopted from the encode_comp_t() function in
306 : * the kern_acct.c file of the FreeBSD operating system. The encoding
307 : * is a 13-bit fraction with a 3-bit (base 8) exponent.
308 : */
309 :
310 : #define MANTSIZE 13 /* 13 bit mantissa. */
311 : #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
312 : #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
313 :
314 : static comp_t encode_comp_t(unsigned long value)
315 : {
316 : int exp, rnd;
317 :
318 : exp = rnd = 0;
319 0 : while (value > MAXFRACT) {
320 0 : rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
321 0 : value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
322 0 : exp++;
323 : }
324 :
325 : /*
326 : * If we need to round up, do it (and handle overflow correctly).
327 : */
328 0 : if (rnd && (++value > MAXFRACT)) {
329 0 : value >>= EXPSIZE;
330 0 : exp++;
331 : }
332 :
333 : /*
334 : * Clean it up and polish it off.
335 : */
336 0 : exp <<= MANTSIZE; /* Shift the exponent into place */
337 0 : exp += value; /* and add on the mantissa. */
338 0 : return exp;
339 : }
340 :
341 : #if ACCT_VERSION == 1 || ACCT_VERSION == 2
342 : /*
343 : * encode an u64 into a comp2_t (24 bits)
344 : *
345 : * Format: 5 bit base 2 exponent, 20 bits mantissa.
346 : * The leading bit of the mantissa is not stored, but implied for
347 : * non-zero exponents.
348 : * Largest encodable value is 50 bits.
349 : */
350 :
351 : #define MANTSIZE2 20 /* 20 bit mantissa. */
352 : #define EXPSIZE2 5 /* 5 bit base 2 exponent. */
353 : #define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
354 : #define MAXEXP2 ((1 << EXPSIZE2) - 1) /* Maximum exponent. */
355 :
356 : static comp2_t encode_comp2_t(u64 value)
357 : {
358 : int exp, rnd;
359 :
360 : exp = (value > (MAXFRACT2>>1));
361 : rnd = 0;
362 : while (value > MAXFRACT2) {
363 : rnd = value & 1;
364 : value >>= 1;
365 : exp++;
366 : }
367 :
368 : /*
369 : * If we need to round up, do it (and handle overflow correctly).
370 : */
371 : if (rnd && (++value > MAXFRACT2)) {
372 : value >>= 1;
373 : exp++;
374 : }
375 :
376 : if (exp > MAXEXP2) {
377 : /* Overflow. Return largest representable number instead. */
378 : return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
379 : } else {
380 : return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
381 : }
382 : }
383 : #endif
384 :
385 : #if ACCT_VERSION == 3
386 : /*
387 : * encode an u64 into a 32 bit IEEE float
388 : */
389 : static u32 encode_float(u64 value)
390 : {
391 : unsigned exp = 190;
392 : unsigned u;
393 :
394 0 : if (value == 0)
395 : return 0;
396 0 : while ((s64)value > 0) {
397 0 : value <<= 1;
398 0 : exp--;
399 : }
400 0 : u = (u32)(value >> 40) & 0x7fffffu;
401 0 : return u | (exp << 23);
402 : }
403 : #endif
404 :
405 : /*
406 : * Write an accounting entry for an exiting process
407 : *
408 : * The acct_process() call is the workhorse of the process
409 : * accounting system. The struct acct is built here and then written
410 : * into the accounting file. This function should only be called from
411 : * do_exit() or when switching to a different output file.
412 : */
413 :
414 0 : static void fill_ac(acct_t *ac)
415 : {
416 0 : struct pacct_struct *pacct = ¤t->signal->pacct;
417 : u64 elapsed, run_time;
418 : struct tty_struct *tty;
419 :
420 : /*
421 : * Fill the accounting struct with the needed info as recorded
422 : * by the different kernel functions.
423 : */
424 0 : memset(ac, 0, sizeof(acct_t));
425 :
426 0 : ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER;
427 0 : strlcpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
428 :
429 : /* calculate run_time in nsec*/
430 : run_time = ktime_get_ns();
431 0 : run_time -= current->group_leader->start_time;
432 : /* convert nsec -> AHZ */
433 : elapsed = nsec_to_AHZ(run_time);
434 : #if ACCT_VERSION == 3
435 0 : ac->ac_etime = encode_float(elapsed);
436 : #else
437 : ac->ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
438 : (unsigned long) elapsed : (unsigned long) -1l);
439 : #endif
440 : #if ACCT_VERSION == 1 || ACCT_VERSION == 2
441 : {
442 : /* new enlarged etime field */
443 : comp2_t etime = encode_comp2_t(elapsed);
444 :
445 : ac->ac_etime_hi = etime >> 16;
446 : ac->ac_etime_lo = (u16) etime;
447 : }
448 : #endif
449 0 : do_div(elapsed, AHZ);
450 0 : ac->ac_btime = get_seconds() - elapsed;
451 : #if ACCT_VERSION==2
452 : ac->ac_ahz = AHZ;
453 : #endif
454 :
455 : spin_lock_irq(¤t->sighand->siglock);
456 0 : tty = current->signal->tty; /* Safe as we hold the siglock */
457 0 : ac->ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
458 0 : ac->ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
459 0 : ac->ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
460 0 : ac->ac_flag = pacct->ac_flag;
461 0 : ac->ac_mem = encode_comp_t(pacct->ac_mem);
462 0 : ac->ac_minflt = encode_comp_t(pacct->ac_minflt);
463 0 : ac->ac_majflt = encode_comp_t(pacct->ac_majflt);
464 0 : ac->ac_exitcode = pacct->ac_exitcode;
465 : spin_unlock_irq(¤t->sighand->siglock);
466 0 : }
467 : /*
468 : * do_acct_process does all actual work. Caller holds the reference to file.
469 : */
470 0 : static void do_acct_process(struct bsd_acct_struct *acct)
471 : {
472 : acct_t ac;
473 : unsigned long flim;
474 : const struct cred *orig_cred;
475 0 : struct file *file = acct->file;
476 :
477 : /*
478 : * Accounting records are not subject to resource limits.
479 : */
480 0 : flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
481 0 : current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
482 : /* Perform file operations on behalf of whoever enabled accounting */
483 0 : orig_cred = override_creds(file->f_cred);
484 :
485 : /*
486 : * First check to see if there is enough free_space to continue
487 : * the process accounting system.
488 : */
489 0 : if (!check_free_space(acct))
490 : goto out;
491 :
492 0 : fill_ac(&ac);
493 : /* we really need to bite the bullet and change layout */
494 0 : ac.ac_uid = from_kuid_munged(file->f_cred->user_ns, orig_cred->uid);
495 0 : ac.ac_gid = from_kgid_munged(file->f_cred->user_ns, orig_cred->gid);
496 : #if ACCT_VERSION == 1 || ACCT_VERSION == 2
497 : /* backward-compatible 16 bit fields */
498 : ac.ac_uid16 = ac.ac_uid;
499 : ac.ac_gid16 = ac.ac_gid;
500 : #endif
501 : #if ACCT_VERSION == 3
502 : {
503 0 : struct pid_namespace *ns = acct->ns;
504 :
505 0 : ac.ac_pid = task_tgid_nr_ns(current, ns);
506 : rcu_read_lock();
507 0 : ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent),
508 : ns);
509 : rcu_read_unlock();
510 : }
511 : #endif
512 : /*
513 : * Get freeze protection. If the fs is frozen, just skip the write
514 : * as we could deadlock the system otherwise.
515 : */
516 0 : if (file_start_write_trylock(file)) {
517 : /* it's been opened O_APPEND, so position is irrelevant */
518 0 : loff_t pos = 0;
519 0 : __kernel_write(file, (char *)&ac, sizeof(acct_t), &pos);
520 : file_end_write(file);
521 : }
522 : out:
523 0 : current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
524 0 : revert_creds(orig_cred);
525 0 : }
526 :
527 : /**
528 : * acct_collect - collect accounting information into pacct_struct
529 : * @exitcode: task exit code
530 : * @group_dead: not 0, if this thread is the last one in the process.
531 : */
532 2914 : void acct_collect(long exitcode, int group_dead)
533 : {
534 2914 : struct pacct_struct *pacct = ¤t->signal->pacct;
535 : cputime_t utime, stime;
536 : unsigned long vsize = 0;
537 :
538 2914 : if (group_dead && current->mm) {
539 : struct vm_area_struct *vma;
540 :
541 2881 : down_read(¤t->mm->mmap_sem);
542 2881 : vma = current->mm->mmap;
543 85449 : while (vma) {
544 79687 : vsize += vma->vm_end - vma->vm_start;
545 79687 : vma = vma->vm_next;
546 : }
547 2881 : up_read(¤t->mm->mmap_sem);
548 : }
549 :
550 : spin_lock_irq(¤t->sighand->siglock);
551 2914 : if (group_dead)
552 2914 : pacct->ac_mem = vsize / 1024;
553 5828 : if (thread_group_leader(current)) {
554 2914 : pacct->ac_exitcode = exitcode;
555 2914 : if (current->flags & PF_FORKNOEXEC)
556 800 : pacct->ac_flag |= AFORK;
557 : }
558 2914 : if (current->flags & PF_SUPERPRIV)
559 231 : pacct->ac_flag |= ASU;
560 2914 : if (current->flags & PF_DUMPCORE)
561 0 : pacct->ac_flag |= ACORE;
562 2914 : if (current->flags & PF_SIGNALED)
563 10 : pacct->ac_flag |= AXSIG;
564 2914 : task_cputime(current, &utime, &stime);
565 2914 : pacct->ac_utime += utime;
566 2914 : pacct->ac_stime += stime;
567 2914 : pacct->ac_minflt += current->min_flt;
568 2914 : pacct->ac_majflt += current->maj_flt;
569 : spin_unlock_irq(¤t->sighand->siglock);
570 2914 : }
571 :
572 0 : static void slow_acct_process(struct pid_namespace *ns)
573 : {
574 0 : for ( ; ns; ns = ns->parent) {
575 0 : struct bsd_acct_struct *acct = acct_get(ns);
576 0 : if (acct) {
577 0 : do_acct_process(acct);
578 0 : mutex_unlock(&acct->lock);
579 0 : pin_put(&acct->pin);
580 : }
581 : }
582 0 : }
583 :
584 : /**
585 : * acct_process
586 : *
587 : * handles process accounting for an exiting task
588 : */
589 2914 : void acct_process(void)
590 : {
591 : struct pid_namespace *ns;
592 :
593 : /*
594 : * This loop is safe lockless, since current is still
595 : * alive and holds its namespace, which in turn holds
596 : * its parent.
597 : */
598 5828 : for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
599 2914 : if (ns->bacct)
600 : break;
601 : }
602 2914 : if (unlikely(ns))
603 0 : slow_acct_process(ns);
604 2914 : }
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