mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-19 23:20:02 +07:00
4d9570158b
As Tsukada explains, the time_is_before_jiffies(acct->needcheck) check is very wrong, we need time_is_after_jiffies() to make sys_acct() work. Ignoring the overflows, the code should "goto out" if needcheck > jiffies, while currently it checks "needcheck < jiffies" and thus in the likely case check_free_space() does nothing until jiffies overflow. In particular this means that sys_acct() is simply broken, acct_on() sets acct->needcheck = jiffies and expects that check_free_space() should set acct->active = 1 after the free-space check, but this won't happen if jiffies increments in between. This was broken by commit32dc730860
("get rid of timer in kern/acct.c") in 2011, then another (correct) commit795a2f22a8
("acct() should honour the limits from the very beginning") made the problem more visible. Link: http://lkml.kernel.org/r/20171213133940.GA6554@redhat.com Fixes:32dc730860
("get rid of timer in kern/acct.c") Reported-by: TSUKADA Koutaro <tsukada@ascade.co.jp> Suggested-by: TSUKADA Koutaro <tsukada@ascade.co.jp> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
607 lines
15 KiB
C
607 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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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 <linux/uaccess.h>
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#include <linux/sched/cputime.h>
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#include <asm/div64.h>
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#include <linux/blkdev.h> /* sector_div */
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#include <linux/pid_namespace.h>
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#include <linux/fs_pin.h>
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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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struct bsd_acct_struct {
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struct fs_pin pin;
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atomic_long_t count;
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struct rcu_head rcu;
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struct mutex lock;
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int active;
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unsigned long needcheck;
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struct file *file;
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struct pid_namespace *ns;
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struct work_struct work;
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struct completion done;
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};
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static void do_acct_process(struct bsd_acct_struct *acct);
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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 bsd_acct_struct *acct)
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{
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struct kstatfs sbuf;
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if (time_is_after_jiffies(acct->needcheck))
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goto out;
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/* May block */
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if (vfs_statfs(&acct->file->f_path, &sbuf))
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goto out;
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if (acct->active) {
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u64 suspend = sbuf.f_blocks * SUSPEND;
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do_div(suspend, 100);
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if (sbuf.f_bavail <= suspend) {
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acct->active = 0;
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pr_info("Process accounting paused\n");
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}
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} else {
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u64 resume = sbuf.f_blocks * RESUME;
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do_div(resume, 100);
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if (sbuf.f_bavail >= resume) {
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acct->active = 1;
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pr_info("Process accounting resumed\n");
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}
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}
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acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
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out:
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return acct->active;
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}
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static void acct_put(struct bsd_acct_struct *p)
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{
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if (atomic_long_dec_and_test(&p->count))
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kfree_rcu(p, rcu);
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}
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static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)
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{
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return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;
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}
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static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
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{
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struct bsd_acct_struct *res;
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again:
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smp_rmb();
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rcu_read_lock();
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res = to_acct(READ_ONCE(ns->bacct));
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if (!res) {
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rcu_read_unlock();
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return NULL;
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}
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if (!atomic_long_inc_not_zero(&res->count)) {
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rcu_read_unlock();
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cpu_relax();
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goto again;
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}
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rcu_read_unlock();
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mutex_lock(&res->lock);
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if (res != to_acct(READ_ONCE(ns->bacct))) {
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mutex_unlock(&res->lock);
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acct_put(res);
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goto again;
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}
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return res;
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}
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static void acct_pin_kill(struct fs_pin *pin)
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{
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struct bsd_acct_struct *acct = to_acct(pin);
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mutex_lock(&acct->lock);
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do_acct_process(acct);
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schedule_work(&acct->work);
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wait_for_completion(&acct->done);
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cmpxchg(&acct->ns->bacct, pin, NULL);
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mutex_unlock(&acct->lock);
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pin_remove(pin);
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acct_put(acct);
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}
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static void close_work(struct work_struct *work)
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{
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struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
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struct file *file = acct->file;
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if (file->f_op->flush)
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file->f_op->flush(file, NULL);
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__fput_sync(file);
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complete(&acct->done);
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}
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static int acct_on(struct filename *pathname)
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{
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struct file *file;
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struct vfsmount *mnt, *internal;
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struct pid_namespace *ns = task_active_pid_ns(current);
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struct bsd_acct_struct *acct;
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struct fs_pin *old;
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int err;
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acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
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if (!acct)
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return -ENOMEM;
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/* Difference from BSD - they don't do O_APPEND */
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file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
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if (IS_ERR(file)) {
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kfree(acct);
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return PTR_ERR(file);
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}
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if (!S_ISREG(file_inode(file)->i_mode)) {
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kfree(acct);
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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_mode & FMODE_CAN_WRITE)) {
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kfree(acct);
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filp_close(file, NULL);
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return -EIO;
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}
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internal = mnt_clone_internal(&file->f_path);
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if (IS_ERR(internal)) {
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kfree(acct);
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filp_close(file, NULL);
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return PTR_ERR(internal);
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}
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err = mnt_want_write(internal);
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if (err) {
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mntput(internal);
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kfree(acct);
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filp_close(file, NULL);
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return err;
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}
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mnt = file->f_path.mnt;
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file->f_path.mnt = internal;
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atomic_long_set(&acct->count, 1);
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init_fs_pin(&acct->pin, acct_pin_kill);
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acct->file = file;
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acct->needcheck = jiffies;
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acct->ns = ns;
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mutex_init(&acct->lock);
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INIT_WORK(&acct->work, close_work);
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init_completion(&acct->done);
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mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */
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pin_insert(&acct->pin, mnt);
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rcu_read_lock();
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old = xchg(&ns->bacct, &acct->pin);
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mutex_unlock(&acct->lock);
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pin_kill(old);
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mnt_drop_write(mnt);
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mntput(mnt);
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return 0;
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}
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static DEFINE_MUTEX(acct_on_mutex);
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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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SYSCALL_DEFINE1(acct, const char __user *, name)
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{
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int error = 0;
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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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struct filename *tmp = getname(name);
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if (IS_ERR(tmp))
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return PTR_ERR(tmp);
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mutex_lock(&acct_on_mutex);
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error = acct_on(tmp);
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mutex_unlock(&acct_on_mutex);
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putname(tmp);
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} else {
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rcu_read_lock();
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pin_kill(task_active_pid_ns(current)->bacct);
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}
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return error;
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}
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void acct_exit_ns(struct pid_namespace *ns)
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{
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rcu_read_lock();
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pin_kill(ns->bacct);
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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)
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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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static void fill_ac(acct_t *ac)
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{
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struct pacct_struct *pacct = ¤t->signal->pacct;
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u64 elapsed, run_time;
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struct tty_struct *tty;
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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(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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run_time = ktime_get_ns();
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run_time -= current->group_leader->start_time;
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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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#if ACCT_VERSION==2
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ac->ac_ahz = AHZ;
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#endif
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spin_lock_irq(¤t->sighand->siglock);
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tty = current->signal->tty; /* Safe as we hold the siglock */
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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(nsec_to_AHZ(pacct->ac_utime));
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ac->ac_stime = encode_comp_t(nsec_to_AHZ(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);
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ac->ac_exitcode = pacct->ac_exitcode;
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spin_unlock_irq(¤t->sighand->siglock);
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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 bsd_acct_struct *acct)
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{
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acct_t ac;
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unsigned long flim;
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const struct cred *orig_cred;
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struct file *file = acct->file;
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/*
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* 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;
|
|
/* Perform file operations on behalf of whoever enabled accounting */
|
|
orig_cred = override_creds(file->f_cred);
|
|
|
|
/*
|
|
* First check to see if there is enough free_space to continue
|
|
* the process accounting system.
|
|
*/
|
|
if (!check_free_space(acct))
|
|
goto out;
|
|
|
|
fill_ac(&ac);
|
|
/* we really need to bite the bullet and change layout */
|
|
ac.ac_uid = from_kuid_munged(file->f_cred->user_ns, orig_cred->uid);
|
|
ac.ac_gid = from_kgid_munged(file->f_cred->user_ns, orig_cred->gid);
|
|
#if ACCT_VERSION == 1 || ACCT_VERSION == 2
|
|
/* backward-compatible 16 bit fields */
|
|
ac.ac_uid16 = ac.ac_uid;
|
|
ac.ac_gid16 = ac.ac_gid;
|
|
#endif
|
|
#if ACCT_VERSION == 3
|
|
{
|
|
struct pid_namespace *ns = acct->ns;
|
|
|
|
ac.ac_pid = task_tgid_nr_ns(current, ns);
|
|
rcu_read_lock();
|
|
ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent),
|
|
ns);
|
|
rcu_read_unlock();
|
|
}
|
|
#endif
|
|
/*
|
|
* Get freeze protection. If the fs is frozen, just skip the write
|
|
* as we could deadlock the system otherwise.
|
|
*/
|
|
if (file_start_write_trylock(file)) {
|
|
/* it's been opened O_APPEND, so position is irrelevant */
|
|
loff_t pos = 0;
|
|
__kernel_write(file, &ac, sizeof(acct_t), &pos);
|
|
file_end_write(file);
|
|
}
|
|
out:
|
|
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
|
|
revert_creds(orig_cred);
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
u64 utime, stime;
|
|
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;
|
|
|
|
task_cputime(current, &utime, &stime);
|
|
pacct->ac_utime += utime;
|
|
pacct->ac_stime += stime;
|
|
pacct->ac_minflt += current->min_flt;
|
|
pacct->ac_majflt += current->maj_flt;
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
}
|
|
|
|
static void slow_acct_process(struct pid_namespace *ns)
|
|
{
|
|
for ( ; ns; ns = ns->parent) {
|
|
struct bsd_acct_struct *acct = acct_get(ns);
|
|
if (acct) {
|
|
do_acct_process(acct);
|
|
mutex_unlock(&acct->lock);
|
|
acct_put(acct);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* acct_process
|
|
*
|
|
* handles process accounting for an exiting task
|
|
*/
|
|
void acct_process(void)
|
|
{
|
|
struct pid_namespace *ns;
|
|
|
|
/*
|
|
* This loop is safe lockless, since current is still
|
|
* alive and holds its namespace, which in turn holds
|
|
* its parent.
|
|
*/
|
|
for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
|
|
if (ns->bacct)
|
|
break;
|
|
}
|
|
if (unlikely(ns))
|
|
slow_acct_process(ns);
|
|
}
|