4 * BSD Process Accounting for Linux
6 * Author: Marco van Wieringen <mvw@planets.elm.net>
8 * Some code based on ideas and code from:
9 * Thomas K. Dyas <tdyas@eden.rutgers.edu>
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.
17 * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
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.
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.
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.
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.
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.
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 <asm/uaccess.h>
59 #include <asm/div64.h>
60 #include <linux/blkdev.h> /* sector_div */
61 #include <linux/pid_namespace.h>
64 * These constants control the amount of freespace that suspend and
65 * resume the process accounting system, and the time delay between
67 * Turned into sysctl-controllable parameters. AV, 12/11/98
70 int acct_parm
[3] = {4, 2, 30};
71 #define RESUME (acct_parm[0]) /* >foo% free space - resume */
72 #define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
73 #define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
76 * External references and all of the globals.
78 static void do_acct_process(struct bsd_acct_struct
*acct
,
79 struct pid_namespace
*ns
, struct file
*);
82 * This structure is used so that all the data protected by lock
83 * can be placed in the same cache line as the lock. This primes
84 * the cache line to have the data after getting the lock.
86 struct bsd_acct_struct
{
88 unsigned long needcheck
;
90 struct pid_namespace
*ns
;
91 struct list_head list
;
94 static DEFINE_SPINLOCK(acct_lock
);
95 static LIST_HEAD(acct_list
);
98 * Check the amount of free space and suspend/resume accordingly.
100 static int check_free_space(struct bsd_acct_struct
*acct
, struct file
*file
)
108 spin_lock(&acct_lock
);
110 if (!file
|| time_is_before_jiffies(acct
->needcheck
))
112 spin_unlock(&acct_lock
);
115 if (vfs_statfs(&file
->f_path
, &sbuf
))
117 suspend
= sbuf
.f_blocks
* SUSPEND
;
118 resume
= sbuf
.f_blocks
* RESUME
;
120 do_div(suspend
, 100);
123 if (sbuf
.f_bavail
<= suspend
)
125 else if (sbuf
.f_bavail
>= resume
)
131 * If some joker switched acct->file under us we'ld better be
132 * silent and _not_ touch anything.
134 spin_lock(&acct_lock
);
135 if (file
!= acct
->file
) {
144 printk(KERN_INFO
"Process accounting paused\n");
149 printk(KERN_INFO
"Process accounting resumed\n");
153 acct
->needcheck
= jiffies
+ ACCT_TIMEOUT
*HZ
;
156 spin_unlock(&acct_lock
);
161 * Close the old accounting file (if currently open) and then replace
162 * it with file (if non-NULL).
164 * NOTE: acct_lock MUST be held on entry and exit.
166 static void acct_file_reopen(struct bsd_acct_struct
*acct
, struct file
*file
,
167 struct pid_namespace
*ns
)
169 struct file
*old_acct
= NULL
;
170 struct pid_namespace
*old_ns
= NULL
;
173 old_acct
= acct
->file
;
178 list_del(&acct
->list
);
183 acct
->needcheck
= jiffies
+ ACCT_TIMEOUT
*HZ
;
185 list_add(&acct
->list
, &acct_list
);
188 mnt_unpin(old_acct
->f_path
.mnt
);
189 spin_unlock(&acct_lock
);
190 do_acct_process(acct
, old_ns
, old_acct
);
191 filp_close(old_acct
, NULL
);
192 spin_lock(&acct_lock
);
196 static int acct_on(struct filename
*pathname
)
199 struct vfsmount
*mnt
;
200 struct pid_namespace
*ns
;
201 struct bsd_acct_struct
*acct
= NULL
;
203 /* Difference from BSD - they don't do O_APPEND */
204 file
= file_open_name(pathname
, O_WRONLY
|O_APPEND
|O_LARGEFILE
, 0);
206 return PTR_ERR(file
);
208 if (!S_ISREG(file_inode(file
)->i_mode
)) {
209 filp_close(file
, NULL
);
213 if (!file
->f_op
->write
) {
214 filp_close(file
, NULL
);
218 ns
= task_active_pid_ns(current
);
219 if (ns
->bacct
== NULL
) {
220 acct
= kzalloc(sizeof(struct bsd_acct_struct
), GFP_KERNEL
);
222 filp_close(file
, NULL
);
227 spin_lock(&acct_lock
);
228 if (ns
->bacct
== NULL
) {
233 mnt
= file
->f_path
.mnt
;
235 acct_file_reopen(ns
->bacct
, file
, ns
);
236 spin_unlock(&acct_lock
);
238 mntput(mnt
); /* it's pinned, now give up active reference */
245 * sys_acct - enable/disable process accounting
246 * @name: file name for accounting records or NULL to shutdown accounting
248 * Returns 0 for success or negative errno values for failure.
250 * sys_acct() is the only system call needed to implement process
251 * accounting. It takes the name of the file where accounting records
252 * should be written. If the filename is NULL, accounting will be
255 SYSCALL_DEFINE1(acct
, const char __user
*, name
)
259 if (!capable(CAP_SYS_PACCT
))
263 struct filename
*tmp
= getname(name
);
265 return (PTR_ERR(tmp
));
266 error
= acct_on(tmp
);
269 struct bsd_acct_struct
*acct
;
271 acct
= task_active_pid_ns(current
)->bacct
;
275 spin_lock(&acct_lock
);
276 acct_file_reopen(acct
, NULL
, NULL
);
277 spin_unlock(&acct_lock
);
284 * acct_auto_close - turn off a filesystem's accounting if it is on
285 * @m: vfsmount being shut down
287 * If the accounting is turned on for a file in the subtree pointed to
288 * to by m, turn accounting off. Done when m is about to die.
290 void acct_auto_close_mnt(struct vfsmount
*m
)
292 struct bsd_acct_struct
*acct
;
294 spin_lock(&acct_lock
);
296 list_for_each_entry(acct
, &acct_list
, list
)
297 if (acct
->file
&& acct
->file
->f_path
.mnt
== m
) {
298 acct_file_reopen(acct
, NULL
, NULL
);
301 spin_unlock(&acct_lock
);
305 * acct_auto_close - turn off a filesystem's accounting if it is on
306 * @sb: super block for the filesystem
308 * If the accounting is turned on for a file in the filesystem pointed
309 * to by sb, turn accounting off.
311 void acct_auto_close(struct super_block
*sb
)
313 struct bsd_acct_struct
*acct
;
315 spin_lock(&acct_lock
);
317 list_for_each_entry(acct
, &acct_list
, list
)
318 if (acct
->file
&& acct
->file
->f_path
.dentry
->d_sb
== sb
) {
319 acct_file_reopen(acct
, NULL
, NULL
);
322 spin_unlock(&acct_lock
);
325 void acct_exit_ns(struct pid_namespace
*ns
)
327 struct bsd_acct_struct
*acct
= ns
->bacct
;
332 spin_lock(&acct_lock
);
333 if (acct
->file
!= NULL
)
334 acct_file_reopen(acct
, NULL
, NULL
);
335 spin_unlock(&acct_lock
);
341 * encode an unsigned long into a comp_t
343 * This routine has been adopted from the encode_comp_t() function in
344 * the kern_acct.c file of the FreeBSD operating system. The encoding
345 * is a 13-bit fraction with a 3-bit (base 8) exponent.
348 #define MANTSIZE 13 /* 13 bit mantissa. */
349 #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
350 #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
352 static comp_t
encode_comp_t(unsigned long value
)
357 while (value
> MAXFRACT
) {
358 rnd
= value
& (1 << (EXPSIZE
- 1)); /* Round up? */
359 value
>>= EXPSIZE
; /* Base 8 exponent == 3 bit shift. */
364 * If we need to round up, do it (and handle overflow correctly).
366 if (rnd
&& (++value
> MAXFRACT
)) {
372 * Clean it up and polish it off.
374 exp
<<= MANTSIZE
; /* Shift the exponent into place */
375 exp
+= value
; /* and add on the mantissa. */
379 #if ACCT_VERSION==1 || ACCT_VERSION==2
381 * encode an u64 into a comp2_t (24 bits)
383 * Format: 5 bit base 2 exponent, 20 bits mantissa.
384 * The leading bit of the mantissa is not stored, but implied for
385 * non-zero exponents.
386 * Largest encodable value is 50 bits.
389 #define MANTSIZE2 20 /* 20 bit mantissa. */
390 #define EXPSIZE2 5 /* 5 bit base 2 exponent. */
391 #define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
392 #define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */
394 static comp2_t
encode_comp2_t(u64 value
)
398 exp
= (value
> (MAXFRACT2
>>1));
400 while (value
> MAXFRACT2
) {
407 * If we need to round up, do it (and handle overflow correctly).
409 if (rnd
&& (++value
> MAXFRACT2
)) {
415 /* Overflow. Return largest representable number instead. */
416 return (1ul << (MANTSIZE2
+EXPSIZE2
-1)) - 1;
418 return (value
& (MAXFRACT2
>>1)) | (exp
<< (MANTSIZE2
-1));
425 * encode an u64 into a 32 bit IEEE float
427 static u32
encode_float(u64 value
)
432 if (value
==0) return 0;
433 while ((s64
)value
> 0){
437 u
= (u32
)(value
>> 40) & 0x7fffffu
;
438 return u
| (exp
<< 23);
443 * Write an accounting entry for an exiting process
445 * The acct_process() call is the workhorse of the process
446 * accounting system. The struct acct is built here and then written
447 * into the accounting file. This function should only be called from
448 * do_exit() or when switching to a different output file.
452 * do_acct_process does all actual work. Caller holds the reference to file.
454 static void do_acct_process(struct bsd_acct_struct
*acct
,
455 struct pid_namespace
*ns
, struct file
*file
)
457 struct pacct_struct
*pacct
= ¤t
->signal
->pacct
;
463 struct timespec uptime
;
464 struct tty_struct
*tty
;
465 const struct cred
*orig_cred
;
467 /* Perform file operations on behalf of whoever enabled accounting */
468 orig_cred
= override_creds(file
->f_cred
);
471 * First check to see if there is enough free_space to continue
472 * the process accounting system.
474 if (!check_free_space(acct
, file
))
478 * Fill the accounting struct with the needed info as recorded
479 * by the different kernel functions.
481 memset(&ac
, 0, sizeof(acct_t
));
483 ac
.ac_version
= ACCT_VERSION
| ACCT_BYTEORDER
;
484 strlcpy(ac
.ac_comm
, current
->comm
, sizeof(ac
.ac_comm
));
486 /* calculate run_time in nsec*/
487 do_posix_clock_monotonic_gettime(&uptime
);
488 run_time
= (u64
)uptime
.tv_sec
*NSEC_PER_SEC
+ uptime
.tv_nsec
;
489 run_time
-= (u64
)current
->group_leader
->start_time
.tv_sec
* NSEC_PER_SEC
490 + current
->group_leader
->start_time
.tv_nsec
;
491 /* convert nsec -> AHZ */
492 elapsed
= nsec_to_AHZ(run_time
);
494 ac
.ac_etime
= encode_float(elapsed
);
496 ac
.ac_etime
= encode_comp_t(elapsed
< (unsigned long) -1l ?
497 (unsigned long) elapsed
: (unsigned long) -1l);
499 #if ACCT_VERSION==1 || ACCT_VERSION==2
501 /* new enlarged etime field */
502 comp2_t etime
= encode_comp2_t(elapsed
);
503 ac
.ac_etime_hi
= etime
>> 16;
504 ac
.ac_etime_lo
= (u16
) etime
;
507 do_div(elapsed
, AHZ
);
508 ac
.ac_btime
= get_seconds() - elapsed
;
509 /* we really need to bite the bullet and change layout */
510 ac
.ac_uid
= from_kuid_munged(file
->f_cred
->user_ns
, orig_cred
->uid
);
511 ac
.ac_gid
= from_kgid_munged(file
->f_cred
->user_ns
, orig_cred
->gid
);
515 #if ACCT_VERSION==1 || ACCT_VERSION==2
516 /* backward-compatible 16 bit fields */
517 ac
.ac_uid16
= ac
.ac_uid
;
518 ac
.ac_gid16
= ac
.ac_gid
;
521 ac
.ac_pid
= task_tgid_nr_ns(current
, ns
);
523 ac
.ac_ppid
= task_tgid_nr_ns(rcu_dereference(current
->real_parent
), ns
);
527 spin_lock_irq(¤t
->sighand
->siglock
);
528 tty
= current
->signal
->tty
; /* Safe as we hold the siglock */
529 ac
.ac_tty
= tty
? old_encode_dev(tty_devnum(tty
)) : 0;
530 ac
.ac_utime
= encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct
->ac_utime
)));
531 ac
.ac_stime
= encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct
->ac_stime
)));
532 ac
.ac_flag
= pacct
->ac_flag
;
533 ac
.ac_mem
= encode_comp_t(pacct
->ac_mem
);
534 ac
.ac_minflt
= encode_comp_t(pacct
->ac_minflt
);
535 ac
.ac_majflt
= encode_comp_t(pacct
->ac_majflt
);
536 ac
.ac_exitcode
= pacct
->ac_exitcode
;
537 spin_unlock_irq(¤t
->sighand
->siglock
);
538 ac
.ac_io
= encode_comp_t(0 /* current->io_usage */); /* %% */
539 ac
.ac_rw
= encode_comp_t(ac
.ac_io
/ 1024);
540 ac
.ac_swaps
= encode_comp_t(0);
543 * Get freeze protection. If the fs is frozen, just skip the write
544 * as we could deadlock the system otherwise.
546 if (!file_start_write_trylock(file
))
549 * Kernel segment override to datasegment and write it
550 * to the accounting file.
555 * Accounting records are not subject to resource limits.
557 flim
= current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
;
558 current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
= RLIM_INFINITY
;
559 file
->f_op
->write(file
, (char *)&ac
,
560 sizeof(acct_t
), &file
->f_pos
);
561 current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
= flim
;
563 file_end_write(file
);
565 revert_creds(orig_cred
);
569 * acct_collect - collect accounting information into pacct_struct
570 * @exitcode: task exit code
571 * @group_dead: not 0, if this thread is the last one in the process.
573 void acct_collect(long exitcode
, int group_dead
)
575 struct pacct_struct
*pacct
= ¤t
->signal
->pacct
;
576 cputime_t utime
, stime
;
577 unsigned long vsize
= 0;
579 if (group_dead
&& current
->mm
) {
580 struct vm_area_struct
*vma
;
581 down_read(¤t
->mm
->mmap_sem
);
582 vma
= current
->mm
->mmap
;
584 vsize
+= vma
->vm_end
- vma
->vm_start
;
587 up_read(¤t
->mm
->mmap_sem
);
590 spin_lock_irq(¤t
->sighand
->siglock
);
592 pacct
->ac_mem
= vsize
/ 1024;
593 if (thread_group_leader(current
)) {
594 pacct
->ac_exitcode
= exitcode
;
595 if (current
->flags
& PF_FORKNOEXEC
)
596 pacct
->ac_flag
|= AFORK
;
598 if (current
->flags
& PF_SUPERPRIV
)
599 pacct
->ac_flag
|= ASU
;
600 if (current
->flags
& PF_DUMPCORE
)
601 pacct
->ac_flag
|= ACORE
;
602 if (current
->flags
& PF_SIGNALED
)
603 pacct
->ac_flag
|= AXSIG
;
604 task_cputime(current
, &utime
, &stime
);
605 pacct
->ac_utime
+= utime
;
606 pacct
->ac_stime
+= stime
;
607 pacct
->ac_minflt
+= current
->min_flt
;
608 pacct
->ac_majflt
+= current
->maj_flt
;
609 spin_unlock_irq(¤t
->sighand
->siglock
);
612 static void acct_process_in_ns(struct pid_namespace
*ns
)
614 struct file
*file
= NULL
;
615 struct bsd_acct_struct
*acct
;
619 * accelerate the common fastpath:
621 if (!acct
|| !acct
->file
)
624 spin_lock(&acct_lock
);
626 if (unlikely(!file
)) {
627 spin_unlock(&acct_lock
);
631 spin_unlock(&acct_lock
);
633 do_acct_process(acct
, ns
, file
);
638 * acct_process - now just a wrapper around acct_process_in_ns,
639 * which in turn is a wrapper around do_acct_process.
641 * handles process accounting for an exiting task
643 void acct_process(void)
645 struct pid_namespace
*ns
;
648 * This loop is safe lockless, since current is still
649 * alive and holds its namespace, which in turn holds
652 for (ns
= task_active_pid_ns(current
); ns
!= NULL
; ns
= ns
->parent
)
653 acct_process_in_ns(ns
);
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