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![Roland McGrath](/assets/img/avatar_default.png)
The ac_ppid field reported in process accounting records should match what getppid() would have returned to that process, regardless of whether a debugger is attached. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
599 lines
16 KiB
C
599 lines
16 KiB
C
/*
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* linux/kernel/acct.c
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*
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* BSD Process Accounting for Linux
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*
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* Author: Marco van Wieringen <mvw@planets.elm.net>
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*
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* Some code based on ideas and code from:
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* Thomas K. Dyas <tdyas@eden.rutgers.edu>
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*
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* This file implements BSD-style process accounting. Whenever any
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* process exits, an accounting record of type "struct acct" is
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* written to the file specified with the acct() system call. It is
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* up to user-level programs to do useful things with the accounting
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* log. The kernel just provides the raw accounting information.
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*
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* (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
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*
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* Plugged two leaks. 1) It didn't return acct_file into the free_filps if
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* the file happened to be read-only. 2) If the accounting was suspended
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* due to the lack of space it happily allowed to reopen it and completely
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* lost the old acct_file. 3/10/98, Al Viro.
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*
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* Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
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* XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
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*
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* Fixed a nasty interaction with with sys_umount(). If the accointing
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* was suspeneded we failed to stop it on umount(). Messy.
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* Another one: remount to readonly didn't stop accounting.
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* Question: what should we do if we have CAP_SYS_ADMIN but not
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* CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
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* unless we are messing with the root. In that case we are getting a
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* real mess with do_remount_sb(). 9/11/98, AV.
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*
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* Fixed a bunch of races (and pair of leaks). Probably not the best way,
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* but this one obviously doesn't introduce deadlocks. Later. BTW, found
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* one race (and leak) in BSD implementation.
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* OK, that's better. ANOTHER race and leak in BSD variant. There always
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* is one more bug... 10/11/98, AV.
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*
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* Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
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* ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
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* a struct file opened for write. Fixed. 2/6/2000, AV.
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*/
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/acct.h>
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#include <linux/capability.h>
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#include <linux/file.h>
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#include <linux/tty.h>
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#include <linux/security.h>
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#include <linux/vfs.h>
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#include <linux/jiffies.h>
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#include <linux/times.h>
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#include <linux/syscalls.h>
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#include <linux/mount.h>
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#include <asm/uaccess.h>
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#include <asm/div64.h>
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#include <linux/blkdev.h> /* sector_div */
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/*
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* These constants control the amount of freespace that suspend and
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* resume the process accounting system, and the time delay between
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* each check.
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* Turned into sysctl-controllable parameters. AV, 12/11/98
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*/
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int acct_parm[3] = {4, 2, 30};
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#define RESUME (acct_parm[0]) /* >foo% free space - resume */
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#define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
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#define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
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/*
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* External references and all of the globals.
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*/
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static void do_acct_process(struct file *);
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/*
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* This structure is used so that all the data protected by lock
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* can be placed in the same cache line as the lock. This primes
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* the cache line to have the data after getting the lock.
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*/
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struct acct_glbs {
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spinlock_t lock;
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volatile int active;
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volatile int needcheck;
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struct file *file;
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struct timer_list timer;
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};
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static struct acct_glbs acct_globals __cacheline_aligned =
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{__SPIN_LOCK_UNLOCKED(acct_globals.lock)};
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/*
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* Called whenever the timer says to check the free space.
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*/
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static void acct_timeout(unsigned long unused)
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{
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acct_globals.needcheck = 1;
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}
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/*
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* Check the amount of free space and suspend/resume accordingly.
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*/
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static int check_free_space(struct file *file)
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{
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struct kstatfs sbuf;
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int res;
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int act;
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sector_t resume;
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sector_t suspend;
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spin_lock(&acct_globals.lock);
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res = acct_globals.active;
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if (!file || !acct_globals.needcheck)
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goto out;
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spin_unlock(&acct_globals.lock);
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/* May block */
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if (vfs_statfs(file->f_path.dentry, &sbuf))
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return res;
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suspend = sbuf.f_blocks * SUSPEND;
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resume = sbuf.f_blocks * RESUME;
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sector_div(suspend, 100);
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sector_div(resume, 100);
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if (sbuf.f_bavail <= suspend)
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act = -1;
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else if (sbuf.f_bavail >= resume)
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act = 1;
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else
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act = 0;
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/*
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* If some joker switched acct_globals.file under us we'ld better be
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* silent and _not_ touch anything.
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*/
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spin_lock(&acct_globals.lock);
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if (file != acct_globals.file) {
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if (act)
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res = act>0;
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goto out;
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}
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if (acct_globals.active) {
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if (act < 0) {
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acct_globals.active = 0;
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printk(KERN_INFO "Process accounting paused\n");
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}
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} else {
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if (act > 0) {
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acct_globals.active = 1;
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printk(KERN_INFO "Process accounting resumed\n");
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}
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}
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del_timer(&acct_globals.timer);
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acct_globals.needcheck = 0;
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acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
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add_timer(&acct_globals.timer);
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res = acct_globals.active;
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out:
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spin_unlock(&acct_globals.lock);
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return res;
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}
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/*
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* Close the old accounting file (if currently open) and then replace
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* it with file (if non-NULL).
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*
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* NOTE: acct_globals.lock MUST be held on entry and exit.
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*/
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static void acct_file_reopen(struct file *file)
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{
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struct file *old_acct = NULL;
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if (acct_globals.file) {
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old_acct = acct_globals.file;
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del_timer(&acct_globals.timer);
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acct_globals.active = 0;
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acct_globals.needcheck = 0;
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acct_globals.file = NULL;
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}
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if (file) {
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acct_globals.file = file;
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acct_globals.needcheck = 0;
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acct_globals.active = 1;
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/* It's been deleted if it was used before so this is safe */
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init_timer(&acct_globals.timer);
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acct_globals.timer.function = acct_timeout;
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acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
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add_timer(&acct_globals.timer);
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}
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if (old_acct) {
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mnt_unpin(old_acct->f_path.mnt);
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spin_unlock(&acct_globals.lock);
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do_acct_process(old_acct);
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filp_close(old_acct, NULL);
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spin_lock(&acct_globals.lock);
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}
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}
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static int acct_on(char *name)
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{
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struct file *file;
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int error;
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/* Difference from BSD - they don't do O_APPEND */
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file = filp_open(name, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
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if (IS_ERR(file))
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return PTR_ERR(file);
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if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) {
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filp_close(file, NULL);
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return -EACCES;
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}
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if (!file->f_op->write) {
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filp_close(file, NULL);
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return -EIO;
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}
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error = security_acct(file);
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if (error) {
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filp_close(file, NULL);
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return error;
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}
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spin_lock(&acct_globals.lock);
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mnt_pin(file->f_path.mnt);
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acct_file_reopen(file);
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spin_unlock(&acct_globals.lock);
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mntput(file->f_path.mnt); /* it's pinned, now give up active reference */
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return 0;
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}
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/**
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* sys_acct - enable/disable process accounting
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* @name: file name for accounting records or NULL to shutdown accounting
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*
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* Returns 0 for success or negative errno values for failure.
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*
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* sys_acct() is the only system call needed to implement process
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* accounting. It takes the name of the file where accounting records
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* should be written. If the filename is NULL, accounting will be
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* shutdown.
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*/
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asmlinkage long sys_acct(const char __user *name)
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{
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int error;
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if (!capable(CAP_SYS_PACCT))
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return -EPERM;
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if (name) {
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char *tmp = getname(name);
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if (IS_ERR(tmp))
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return (PTR_ERR(tmp));
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error = acct_on(tmp);
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putname(tmp);
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} else {
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error = security_acct(NULL);
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if (!error) {
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spin_lock(&acct_globals.lock);
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acct_file_reopen(NULL);
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spin_unlock(&acct_globals.lock);
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}
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}
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return error;
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}
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/**
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* acct_auto_close - turn off a filesystem's accounting if it is on
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* @m: vfsmount being shut down
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*
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* If the accounting is turned on for a file in the subtree pointed to
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* to by m, turn accounting off. Done when m is about to die.
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*/
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void acct_auto_close_mnt(struct vfsmount *m)
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{
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spin_lock(&acct_globals.lock);
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if (acct_globals.file && acct_globals.file->f_path.mnt == m)
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acct_file_reopen(NULL);
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spin_unlock(&acct_globals.lock);
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}
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/**
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* acct_auto_close - turn off a filesystem's accounting if it is on
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* @sb: super block for the filesystem
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*
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* If the accounting is turned on for a file in the filesystem pointed
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* to by sb, turn accounting off.
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*/
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void acct_auto_close(struct super_block *sb)
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{
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spin_lock(&acct_globals.lock);
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if (acct_globals.file &&
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acct_globals.file->f_path.mnt->mnt_sb == sb) {
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acct_file_reopen(NULL);
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}
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spin_unlock(&acct_globals.lock);
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}
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/*
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* encode an unsigned long into a comp_t
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*
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* This routine has been adopted from the encode_comp_t() function in
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* the kern_acct.c file of the FreeBSD operating system. The encoding
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* is a 13-bit fraction with a 3-bit (base 8) exponent.
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*/
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#define MANTSIZE 13 /* 13 bit mantissa. */
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#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
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#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
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static comp_t encode_comp_t(unsigned long value)
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{
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int exp, rnd;
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exp = rnd = 0;
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while (value > MAXFRACT) {
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rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
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value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
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exp++;
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}
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/*
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* If we need to round up, do it (and handle overflow correctly).
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*/
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if (rnd && (++value > MAXFRACT)) {
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value >>= EXPSIZE;
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exp++;
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}
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/*
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* Clean it up and polish it off.
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*/
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exp <<= MANTSIZE; /* Shift the exponent into place */
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exp += value; /* and add on the mantissa. */
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return exp;
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}
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#if ACCT_VERSION==1 || ACCT_VERSION==2
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/*
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* encode an u64 into a comp2_t (24 bits)
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*
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* Format: 5 bit base 2 exponent, 20 bits mantissa.
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* The leading bit of the mantissa is not stored, but implied for
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* non-zero exponents.
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* Largest encodable value is 50 bits.
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*/
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#define MANTSIZE2 20 /* 20 bit mantissa. */
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#define EXPSIZE2 5 /* 5 bit base 2 exponent. */
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#define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
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#define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */
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static comp2_t encode_comp2_t(u64 value)
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{
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int exp, rnd;
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exp = (value > (MAXFRACT2>>1));
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rnd = 0;
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while (value > MAXFRACT2) {
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rnd = value & 1;
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value >>= 1;
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exp++;
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}
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/*
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* If we need to round up, do it (and handle overflow correctly).
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*/
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if (rnd && (++value > MAXFRACT2)) {
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value >>= 1;
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exp++;
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}
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if (exp > MAXEXP2) {
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/* Overflow. Return largest representable number instead. */
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return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
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} else {
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return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
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}
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}
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#endif
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#if ACCT_VERSION==3
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/*
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* encode an u64 into a 32 bit IEEE float
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*/
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static u32 encode_float(u64 value)
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{
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unsigned exp = 190;
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unsigned u;
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if (value==0) return 0;
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while ((s64)value > 0){
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value <<= 1;
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exp--;
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}
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u = (u32)(value >> 40) & 0x7fffffu;
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return u | (exp << 23);
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}
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#endif
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/*
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* Write an accounting entry for an exiting process
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*
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* The acct_process() call is the workhorse of the process
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* accounting system. The struct acct is built here and then written
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* into the accounting file. This function should only be called from
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* do_exit() or when switching to a different output file.
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*/
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/*
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* do_acct_process does all actual work. Caller holds the reference to file.
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*/
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static void do_acct_process(struct file *file)
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{
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struct pacct_struct *pacct = ¤t->signal->pacct;
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acct_t ac;
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mm_segment_t fs;
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unsigned long flim;
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u64 elapsed;
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u64 run_time;
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struct timespec uptime;
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struct tty_struct *tty;
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/*
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* First check to see if there is enough free_space to continue
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* the process accounting system.
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*/
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if (!check_free_space(file))
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return;
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/*
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* Fill the accounting struct with the needed info as recorded
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* by the different kernel functions.
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*/
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memset((caddr_t)&ac, 0, sizeof(acct_t));
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ac.ac_version = ACCT_VERSION | ACCT_BYTEORDER;
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strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));
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/* calculate run_time in nsec*/
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do_posix_clock_monotonic_gettime(&uptime);
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run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
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run_time -= (u64)current->group_leader->start_time.tv_sec * NSEC_PER_SEC
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+ current->group_leader->start_time.tv_nsec;
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/* convert nsec -> AHZ */
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elapsed = nsec_to_AHZ(run_time);
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#if ACCT_VERSION==3
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ac.ac_etime = encode_float(elapsed);
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#else
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ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
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(unsigned long) elapsed : (unsigned long) -1l);
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#endif
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#if ACCT_VERSION==1 || ACCT_VERSION==2
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{
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/* new enlarged etime field */
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comp2_t etime = encode_comp2_t(elapsed);
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ac.ac_etime_hi = etime >> 16;
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ac.ac_etime_lo = (u16) etime;
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}
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#endif
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do_div(elapsed, AHZ);
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ac.ac_btime = get_seconds() - elapsed;
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/* we really need to bite the bullet and change layout */
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ac.ac_uid = current->uid;
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ac.ac_gid = current->gid;
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#if ACCT_VERSION==2
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ac.ac_ahz = AHZ;
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#endif
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#if ACCT_VERSION==1 || ACCT_VERSION==2
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/* backward-compatible 16 bit fields */
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ac.ac_uid16 = current->uid;
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ac.ac_gid16 = current->gid;
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#endif
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#if ACCT_VERSION==3
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ac.ac_pid = current->tgid;
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ac.ac_ppid = current->real_parent->tgid;
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#endif
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spin_lock_irq(¤t->sighand->siglock);
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tty = current->signal->tty;
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ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
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ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
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ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
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ac.ac_flag = pacct->ac_flag;
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ac.ac_mem = encode_comp_t(pacct->ac_mem);
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ac.ac_minflt = encode_comp_t(pacct->ac_minflt);
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ac.ac_majflt = encode_comp_t(pacct->ac_majflt);
|
|
ac.ac_exitcode = pacct->ac_exitcode;
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
ac.ac_io = encode_comp_t(0 /* current->io_usage */); /* %% */
|
|
ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
|
|
ac.ac_swaps = encode_comp_t(0);
|
|
|
|
/*
|
|
* Kernel segment override to datasegment and write it
|
|
* to the accounting file.
|
|
*/
|
|
fs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
/*
|
|
* Accounting records are not subject to resource limits.
|
|
*/
|
|
flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
|
|
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
|
|
file->f_op->write(file, (char *)&ac,
|
|
sizeof(acct_t), &file->f_pos);
|
|
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
|
|
set_fs(fs);
|
|
}
|
|
|
|
/**
|
|
* acct_init_pacct - initialize a new pacct_struct
|
|
* @pacct: per-process accounting info struct to initialize
|
|
*/
|
|
void acct_init_pacct(struct pacct_struct *pacct)
|
|
{
|
|
memset(pacct, 0, sizeof(struct pacct_struct));
|
|
pacct->ac_utime = pacct->ac_stime = cputime_zero;
|
|
}
|
|
|
|
/**
|
|
* acct_collect - collect accounting information into pacct_struct
|
|
* @exitcode: task exit code
|
|
* @group_dead: not 0, if this thread is the last one in the process.
|
|
*/
|
|
void acct_collect(long exitcode, int group_dead)
|
|
{
|
|
struct pacct_struct *pacct = ¤t->signal->pacct;
|
|
unsigned long vsize = 0;
|
|
|
|
if (group_dead && current->mm) {
|
|
struct vm_area_struct *vma;
|
|
down_read(¤t->mm->mmap_sem);
|
|
vma = current->mm->mmap;
|
|
while (vma) {
|
|
vsize += vma->vm_end - vma->vm_start;
|
|
vma = vma->vm_next;
|
|
}
|
|
up_read(¤t->mm->mmap_sem);
|
|
}
|
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
if (group_dead)
|
|
pacct->ac_mem = vsize / 1024;
|
|
if (thread_group_leader(current)) {
|
|
pacct->ac_exitcode = exitcode;
|
|
if (current->flags & PF_FORKNOEXEC)
|
|
pacct->ac_flag |= AFORK;
|
|
}
|
|
if (current->flags & PF_SUPERPRIV)
|
|
pacct->ac_flag |= ASU;
|
|
if (current->flags & PF_DUMPCORE)
|
|
pacct->ac_flag |= ACORE;
|
|
if (current->flags & PF_SIGNALED)
|
|
pacct->ac_flag |= AXSIG;
|
|
pacct->ac_utime = cputime_add(pacct->ac_utime, current->utime);
|
|
pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime);
|
|
pacct->ac_minflt += current->min_flt;
|
|
pacct->ac_majflt += current->maj_flt;
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
}
|
|
|
|
/**
|
|
* acct_process - now just a wrapper around do_acct_process
|
|
* @exitcode: task exit code
|
|
*
|
|
* handles process accounting for an exiting task
|
|
*/
|
|
void acct_process(void)
|
|
{
|
|
struct file *file = NULL;
|
|
|
|
/*
|
|
* accelerate the common fastpath:
|
|
*/
|
|
if (!acct_globals.file)
|
|
return;
|
|
|
|
spin_lock(&acct_globals.lock);
|
|
file = acct_globals.file;
|
|
if (unlikely(!file)) {
|
|
spin_unlock(&acct_globals.lock);
|
|
return;
|
|
}
|
|
get_file(file);
|
|
spin_unlock(&acct_globals.lock);
|
|
|
|
do_acct_process(file);
|
|
fput(file);
|
|
}
|