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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/mm.h>
- #include <linux/slab.h>
- #include <linux/acct.h>
- #include <linux/capability.h>
- #include <linux/file.h>
- #include <linux/tty.h>
- #include <linux/security.h>
- #include <linux/vfs.h>
- #include <linux/jiffies.h>
- #include <linux/times.h>
- #include <linux/syscalls.h>
- #include <linux/mount.h>
- #include <asm/uaccess.h>
- #include <asm/div64.h>
- #include <linux/blkdev.h> /* sector_div */
- /*
- * 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 void do_acct_process(struct file *);
- /*
- * This structure is used so that all the data protected by lock
- * can be placed in the same cache line as the lock. This primes
- * the cache line to have the data after getting the lock.
- */
- struct acct_glbs {
- spinlock_t lock;
- volatile int active;
- volatile int needcheck;
- struct file *file;
- struct timer_list timer;
- };
- static struct acct_glbs acct_globals __cacheline_aligned =
- {__SPIN_LOCK_UNLOCKED(acct_globals.lock)};
- /*
- * Called whenever the timer says to check the free space.
- */
- static void acct_timeout(unsigned long unused)
- {
- acct_globals.needcheck = 1;
- }
- /*
- * Check the amount of free space and suspend/resume accordingly.
- */
- static int check_free_space(struct file *file)
- {
- struct kstatfs sbuf;
- int res;
- int act;
- sector_t resume;
- sector_t suspend;
- spin_lock(&acct_globals.lock);
- res = acct_globals.active;
- if (!file || !acct_globals.needcheck)
- goto out;
- spin_unlock(&acct_globals.lock);
- /* May block */
- if (vfs_statfs(file->f_path.dentry, &sbuf))
- return res;
- suspend = sbuf.f_blocks * SUSPEND;
- resume = sbuf.f_blocks * RESUME;
- sector_div(suspend, 100);
- sector_div(resume, 100);
- if (sbuf.f_bavail <= suspend)
- act = -1;
- else if (sbuf.f_bavail >= resume)
- act = 1;
- else
- act = 0;
- /*
- * If some joker switched acct_globals.file under us we'ld better be
- * silent and _not_ touch anything.
- */
- spin_lock(&acct_globals.lock);
- if (file != acct_globals.file) {
- if (act)
- res = act>0;
- goto out;
- }
- if (acct_globals.active) {
- if (act < 0) {
- acct_globals.active = 0;
- printk(KERN_INFO "Process accounting paused\n");
- }
- } else {
- if (act > 0) {
- acct_globals.active = 1;
- printk(KERN_INFO "Process accounting resumed\n");
- }
- }
- del_timer(&acct_globals.timer);
- acct_globals.needcheck = 0;
- acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
- add_timer(&acct_globals.timer);
- res = acct_globals.active;
- out:
- spin_unlock(&acct_globals.lock);
- return res;
- }
- /*
- * Close the old accounting file (if currently open) and then replace
- * it with file (if non-NULL).
- *
- * NOTE: acct_globals.lock MUST be held on entry and exit.
- */
- static void acct_file_reopen(struct file *file)
- {
- struct file *old_acct = NULL;
- if (acct_globals.file) {
- old_acct = acct_globals.file;
- del_timer(&acct_globals.timer);
- acct_globals.active = 0;
- acct_globals.needcheck = 0;
- acct_globals.file = NULL;
- }
- if (file) {
- acct_globals.file = file;
- acct_globals.needcheck = 0;
- acct_globals.active = 1;
- /* It's been deleted if it was used before so this is safe */
- init_timer(&acct_globals.timer);
- acct_globals.timer.function = acct_timeout;
- acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
- add_timer(&acct_globals.timer);
- }
- if (old_acct) {
- mnt_unpin(old_acct->f_path.mnt);
- spin_unlock(&acct_globals.lock);
- do_acct_process(old_acct);
- filp_close(old_acct, NULL);
- spin_lock(&acct_globals.lock);
- }
- }
- static int acct_on(char *name)
- {
- struct file *file;
- int error;
- /* Difference from BSD - they don't do O_APPEND */
- file = filp_open(name, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
- if (IS_ERR(file))
- return PTR_ERR(file);
- if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) {
- filp_close(file, NULL);
- return -EACCES;
- }
- if (!file->f_op->write) {
- filp_close(file, NULL);
- return -EIO;
- }
- error = security_acct(file);
- if (error) {
- filp_close(file, NULL);
- return error;
- }
- spin_lock(&acct_globals.lock);
- mnt_pin(file->f_path.mnt);
- acct_file_reopen(file);
- spin_unlock(&acct_globals.lock);
- mntput(file->f_path.mnt); /* it's pinned, now give up active reference */
- return 0;
- }
- /**
- * sys_acct - enable/disable process accounting
- * @name: file name for accounting records or NULL to shutdown accounting
- *
- * Returns 0 for success or negative errno values for failure.
- *
- * 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 __user *name)
- {
- int error;
- if (!capable(CAP_SYS_PACCT))
- return -EPERM;
- if (name) {
- char *tmp = getname(name);
- if (IS_ERR(tmp))
- return (PTR_ERR(tmp));
- error = acct_on(tmp);
- putname(tmp);
- } else {
- error = security_acct(NULL);
- if (!error) {
- spin_lock(&acct_globals.lock);
- acct_file_reopen(NULL);
- spin_unlock(&acct_globals.lock);
- }
- }
- return error;
- }
- /**
- * acct_auto_close - turn off a filesystem's accounting if it is on
- * @m: vfsmount being shut down
- *
- * If the accounting is turned on for a file in the subtree pointed to
- * to by m, turn accounting off. Done when m is about to die.
- */
- void acct_auto_close_mnt(struct vfsmount *m)
- {
- spin_lock(&acct_globals.lock);
- if (acct_globals.file && acct_globals.file->f_path.mnt == m)
- acct_file_reopen(NULL);
- spin_unlock(&acct_globals.lock);
- }
- /**
- * acct_auto_close - turn off a filesystem's accounting if it is on
- * @sb: super block for the filesystem
- *
- * If the accounting is turned on for a file in the filesystem pointed
- * to by sb, turn accounting off.
- */
- void acct_auto_close(struct super_block *sb)
- {
- spin_lock(&acct_globals.lock);
- if (acct_globals.file &&
- acct_globals.file->f_path.mnt->mnt_sb == sb) {
- acct_file_reopen(NULL);
- }
- spin_unlock(&acct_globals.lock);
- }
- /*
- * 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;
- }
- #if ACCT_VERSION==1 || ACCT_VERSION==2
- /*
- * encode an u64 into a comp2_t (24 bits)
- *
- * Format: 5 bit base 2 exponent, 20 bits mantissa.
- * The leading bit of the mantissa is not stored, but implied for
- * non-zero exponents.
- * Largest encodable value is 50 bits.
- */
- #define MANTSIZE2 20 /* 20 bit mantissa. */
- #define EXPSIZE2 5 /* 5 bit base 2 exponent. */
- #define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
- #define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */
- static comp2_t encode_comp2_t(u64 value)
- {
- int exp, rnd;
- exp = (value > (MAXFRACT2>>1));
- rnd = 0;
- while (value > MAXFRACT2) {
- rnd = value & 1;
- value >>= 1;
- exp++;
- }
- /*
- * If we need to round up, do it (and handle overflow correctly).
- */
- if (rnd && (++value > MAXFRACT2)) {
- value >>= 1;
- exp++;
- }
- if (exp > MAXEXP2) {
- /* Overflow. Return largest representable number instead. */
- return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
- } else {
- return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
- }
- }
- #endif
- #if ACCT_VERSION==3
- /*
- * encode an u64 into a 32 bit IEEE float
- */
- static u32 encode_float(u64 value)
- {
- unsigned exp = 190;
- unsigned u;
- if (value==0) return 0;
- while ((s64)value > 0){
- value <<= 1;
- exp--;
- }
- u = (u32)(value >> 40) & 0x7fffffu;
- return u | (exp << 23);
- }
- #endif
- /*
- * 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(struct file *file)
- {
- struct pacct_struct *pacct = ¤t->signal->pacct;
- acct_t ac;
- mm_segment_t fs;
- unsigned long flim;
- u64 elapsed;
- u64 run_time;
- struct timespec uptime;
- struct tty_struct *tty;
- /*
- * 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(acct_t));
- ac.ac_version = ACCT_VERSION | ACCT_BYTEORDER;
- strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));
- /* calculate run_time in nsec*/
- do_posix_clock_monotonic_gettime(&uptime);
- run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
- run_time -= (u64)current->group_leader->start_time.tv_sec * NSEC_PER_SEC
- + current->group_leader->start_time.tv_nsec;
- /* convert nsec -> AHZ */
- elapsed = nsec_to_AHZ(run_time);
- #if ACCT_VERSION==3
- ac.ac_etime = encode_float(elapsed);
- #else
- ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
- (unsigned long) elapsed : (unsigned long) -1l);
- #endif
- #if ACCT_VERSION==1 || ACCT_VERSION==2
- {
- /* new enlarged etime field */
- comp2_t etime = encode_comp2_t(elapsed);
- ac.ac_etime_hi = etime >> 16;
- ac.ac_etime_lo = (u16) etime;
- }
- #endif
- do_div(elapsed, AHZ);
- ac.ac_btime = xtime.tv_sec - elapsed;
- /* we really need to bite the bullet and change layout */
- ac.ac_uid = current->uid;
- ac.ac_gid = current->gid;
- #if ACCT_VERSION==2
- ac.ac_ahz = AHZ;
- #endif
- #if ACCT_VERSION==1 || ACCT_VERSION==2
- /* backward-compatible 16 bit fields */
- ac.ac_uid16 = current->uid;
- ac.ac_gid16 = current->gid;
- #endif
- #if ACCT_VERSION==3
- ac.ac_pid = current->tgid;
- ac.ac_ppid = current->parent->tgid;
- #endif
- spin_lock_irq(¤t->sighand->siglock);
- tty = current->signal->tty;
- ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
- ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
- ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
- ac.ac_flag = pacct->ac_flag;
- ac.ac_mem = encode_comp_t(pacct->ac_mem);
- ac.ac_minflt = encode_comp_t(pacct->ac_minflt);
- 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);
- }
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