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/*
* linux/kernel/acct.c
*
* BSD Process Accounting for Linux
*
* Author: Marco van Wieringen <mvw@planets.elm.net>
*
* Some code based on ideas and code from:
* Thomas K. Dyas <tdyas@eden.rutgers.edu>
*
* This file implements BSD-style process accounting. Whenever any
* process exits, an accounting record of type "struct acct" is
* written to the file specified with the acct() system call. It is
* up to user-level programs to do useful things with the accounting
* log. The kernel just provides the raw accounting information.
*
* (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
*
* Plugged two leaks. 1) It didn't return acct_file into the free_filps if
* the file happened to be read-only. 2) If the accounting was suspended
* due to the lack of space it happily allowed to reopen it and completely
* lost the old acct_file. 3/10/98, Al Viro.
*
* Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
* XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
*
* Fixed a nasty interaction with with sys_umount(). If the accointing
* was suspeneded we failed to stop it on umount(). Messy.
* Another one: remount to readonly didn't stop accounting.
* Question: what should we do if we have CAP_SYS_ADMIN but not
* CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
* unless we are messing with the root. In that case we are getting a
* real mess with do_remount_sb(). 9/11/98, AV.
*
* Fixed a bunch of races (and pair of leaks). Probably not the best way,
* but this one obviously doesn't introduce deadlocks. Later. BTW, found
* one race (and leak) in BSD implementation.
* OK, that's better. ANOTHER race and leak in BSD variant. There always
* is one more bug... 10/11/98, AV.
*
* Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
* ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
* a struct file opened for write. Fixed. 2/6/2000, AV.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#ifdef CONFIG_BSD_PROCESS_ACCT
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/acct.h>
#include <linux/smp_lock.h>
#include <linux/file.h>
#include <linux/tty.h>
#include <asm/uaccess.h>
/*
* These constants control the amount of freespace that suspend and
* resume the process accounting system, and the time delay between
* each check.
* Turned into sysctl-controllable parameters. AV, 12/11/98
*/
int acct_parm[3] = {4, 2, 30};
#define RESUME (acct_parm[0]) /* >foo% free space - resume */
#define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
#define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
/*
* External references and all of the globals.
*/
static volatile int acct_active;
static volatile int acct_needcheck;
static struct file *acct_file;
static struct timer_list acct_timer;
static void do_acct_process(long, struct file *);
/*
* Called whenever the timer says to check the free space.
*/
static void acct_timeout(unsigned long unused)
{
acct_needcheck = 1;
}
/*
* Check the amount of free space and suspend/resume accordingly.
*/
static int check_free_space(struct file *file)
{
struct statfs sbuf;
int res;
int act;
lock_kernel();
res = acct_active;
if (!file || !acct_needcheck)
goto out;
unlock_kernel();
/* May block */
if (vfs_statfs(file->f_dentry->d_inode->i_sb, &sbuf))
return res;
if (sbuf.f_bavail <= SUSPEND * sbuf.f_blocks / 100)
act = -1;
else if (sbuf.f_bavail >= RESUME * sbuf.f_blocks / 100)
act = 1;
else
act = 0;
/*
* If some joker switched acct_file under us we'ld better be
* silent and _not_ touch anything.
*/
lock_kernel();
if (file != acct_file) {
if (act)
res = act>0;
goto out;
}
if (acct_active) {
if (act < 0) {
acct_active = 0;
printk(KERN_INFO "Process accounting paused\n");
}
} else {
if (act > 0) {
acct_active = 1;
printk(KERN_INFO "Process accounting resumed\n");
}
}
del_timer(&acct_timer);
acct_needcheck = 0;
acct_timer.expires = jiffies + ACCT_TIMEOUT*HZ;
add_timer(&acct_timer);
res = acct_active;
out:
unlock_kernel();
return res;
}
/*
* sys_acct() is the only system call needed to implement process
* accounting. It takes the name of the file where accounting records
* should be written. If the filename is NULL, accounting will be
* shutdown.
*/
asmlinkage long sys_acct(const char *name)
{
struct file *file = NULL, *old_acct = NULL;
char *tmp;
int error;
if (!capable(CAP_SYS_PACCT))
return -EPERM;
if (name) {
tmp = getname(name);
error = PTR_ERR(tmp);
if (IS_ERR(tmp))
goto out;
/* Difference from BSD - they don't do O_APPEND */
file = filp_open(tmp, O_WRONLY|O_APPEND, 0);
putname(tmp);
if (IS_ERR(file)) {
error = PTR_ERR(file);
goto out;
}
error = -EACCES;
if (!S_ISREG(file->f_dentry->d_inode->i_mode))
goto out_err;
error = -EIO;
if (!file->f_op->write)
goto out_err;
}
error = 0;
lock_kernel();
if (acct_file) {
old_acct = acct_file;
del_timer(&acct_timer);
acct_active = 0;
acct_needcheck = 0;
acct_file = NULL;
}
if (name) {
acct_file = file;
acct_needcheck = 0;
acct_active = 1;
/* It's been deleted if it was used before so this is safe */
init_timer(&acct_timer);
acct_timer.function = acct_timeout;
acct_timer.expires = jiffies + ACCT_TIMEOUT*HZ;
add_timer(&acct_timer);
}
unlock_kernel();
if (old_acct) {
do_acct_process(0,old_acct);
filp_close(old_acct, NULL);
}
out:
return error;
out_err:
filp_close(file, NULL);
goto out;
}
void acct_auto_close(kdev_t dev)
{
lock_kernel();
if (acct_file && acct_file->f_dentry->d_inode->i_dev == dev)
sys_acct(NULL);
unlock_kernel();
}
/*
* encode an unsigned long into a comp_t
*
* This routine has been adopted from the encode_comp_t() function in
* the kern_acct.c file of the FreeBSD operating system. The encoding
* is a 13-bit fraction with a 3-bit (base 8) exponent.
*/
#define MANTSIZE 13 /* 13 bit mantissa. */
#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
static comp_t encode_comp_t(unsigned long value)
{
int exp, rnd;
exp = rnd = 0;
while (value > MAXFRACT) {
rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
exp++;
}
/*
* If we need to round up, do it (and handle overflow correctly).
*/
if (rnd && (++value > MAXFRACT)) {
value >>= EXPSIZE;
exp++;
}
/*
* Clean it up and polish it off.
*/
exp <<= MANTSIZE; /* Shift the exponent into place */
exp += value; /* and add on the mantissa. */
return exp;
}
/*
* Write an accounting entry for an exiting process
*
* The acct_process() call is the workhorse of the process
* accounting system. The struct acct is built here and then written
* into the accounting file. This function should only be called from
* do_exit().
*/
/*
* do_acct_process does all actual work. Caller holds the reference to file.
*/
static void do_acct_process(long exitcode, struct file *file)
{
struct acct ac;
mm_segment_t fs;
unsigned long vsize;
/*
* First check to see if there is enough free_space to continue
* the process accounting system.
*/
if (!check_free_space(file))
return;
/*
* Fill the accounting struct with the needed info as recorded
* by the different kernel functions.
*/
memset((caddr_t)&ac, 0, sizeof(struct acct));
strncpy(ac.ac_comm, current->comm, ACCT_COMM);
ac.ac_comm[ACCT_COMM - 1] = '\0';
ac.ac_btime = CT_TO_SECS(current->start_time) + (xtime.tv_sec - (jiffies / HZ));
ac.ac_etime = encode_comp_t(jiffies - current->start_time);
ac.ac_utime = encode_comp_t(current->times.tms_utime);
ac.ac_stime = encode_comp_t(current->times.tms_stime);
ac.ac_uid = current->uid;
ac.ac_gid = current->gid;
ac.ac_tty = (current->tty) ? kdev_t_to_nr(current->tty->device) : 0;
ac.ac_flag = 0;
if (current->flags & PF_FORKNOEXEC)
ac.ac_flag |= AFORK;
if (current->flags & PF_SUPERPRIV)
ac.ac_flag |= ASU;
if (current->flags & PF_DUMPCORE)
ac.ac_flag |= ACORE;
if (current->flags & PF_SIGNALED)
ac.ac_flag |= AXSIG;
vsize = 0;
if (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);
}
vsize = vsize / 1024;
ac.ac_mem = encode_comp_t(vsize);
ac.ac_io = encode_comp_t(0 /* current->io_usage */); /* %% */
ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
ac.ac_minflt = encode_comp_t(current->min_flt);
ac.ac_majflt = encode_comp_t(current->maj_flt);
ac.ac_swaps = encode_comp_t(current->nswap);
ac.ac_exitcode = exitcode;
/*
* Kernel segment override to datasegment and write it
* to the accounting file.
*/
fs = get_fs();
set_fs(KERNEL_DS);
file->f_op->write(file, (char *)&ac,
sizeof(struct acct), &file->f_pos);
set_fs(fs);
}
/*
* acct_process - now just a wrapper around do_acct_process
*/
int acct_process(long exitcode)
{
struct file *file = NULL;
lock_kernel();
if (acct_file) {
file = acct_file;
get_file(file);
unlock_kernel();
do_acct_process(exitcode, acct_file);
fput(file);
} else
unlock_kernel();
return 0;
}
#else
/*
* Dummy system call when BSD process accounting is not configured
* into the kernel.
*/
asmlinkage long sys_acct(const char * filename)
{
return -ENOSYS;
}
#endif
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