FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_acct.c

     /*-
      * Copyright (c) 1994 Christopher G. Demetriou
      * Copyright (c) 1982, 1986, 1989, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
      * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/5.2/sys/kern/kern_acct.c 118094 2003-07-27 17:04:56Z phk $");
    
    #include "opt_mac.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/sysproto.h>
    #include <sys/proc.h>
    #include <sys/mac.h>
    #include <sys/mount.h>
    #include <sys/vnode.h>
    #include <sys/fcntl.h>
    #include <sys/syslog.h>
    #include <sys/kernel.h>
    #include <sys/sysent.h>
    #include <sys/sysctl.h>
    #include <sys/namei.h>
    #include <sys/acct.h>
    #include <sys/resourcevar.h>
    #include <sys/tty.h>
    
    /*
     * The routines implemented in this file are described in:
     *      Leffler, et al.: The Design and Implementation of the 4.3BSD
     *          UNIX Operating System (Addison Welley, 1989)
     * on pages 62-63.
     *
     * Arguably, to simplify accounting operations, this mechanism should
     * be replaced by one in which an accounting log file (similar to /dev/klog)
     * is read by a user process, etc.  However, that has its own problems.
     */
    
    /*
     * Internal accounting functions.
     * The former's operation is described in Leffler, et al., and the latter
     * was provided by UCB with the 4.4BSD-Lite release
     */
    static comp_t   encode_comp_t(u_long, u_long);
    static void     acctwatch(void *);
    
    /*
     * Accounting callout used for periodic scheduling of acctwatch.
     */
    static struct   callout acctwatch_callout;
    
    /*
     * Accounting vnode pointer, saved vnode pointer, and flags for each.
     */
    static struct   vnode *acctp;
    static struct   ucred *acctcred;
    static int      acctflags;
    static struct   vnode *savacctp;
    static struct   ucred *savacctcred;
    static int      savacctflags;
    
   static struct mtx       acct_mtx;
   MTX_SYSINIT(acct, &acct_mtx, "accounting", MTX_DEF);
   
   /*
    * Values associated with enabling and disabling accounting
    */
   static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
   SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
           &acctsuspend, 0, "percentage of free disk space below which accounting stops");
   
   static int acctresume = 4;      /* resume when free space risen to > 4% */
   SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
           &acctresume, 0, "percentage of free disk space above which accounting resumes");
   
   static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
   SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW,
           &acctchkfreq, 0, "frequency for checking the free space");
   
   /*
    * Accounting system call.  Written based on the specification and
    * previous implementation done by Mark Tinguely.
    *
    * MPSAFE
    */
   int
   acct(td, uap)
           struct thread *td;
           struct acct_args /* {
                   char *path;
           } */ *uap;
   {
           struct nameidata nd;
           int error, flags;
   
           /* Make sure that the caller is root. */
           error = suser(td);
           if (error)
                   return (error);
   
           mtx_lock(&Giant);
           /*
            * If accounting is to be started to a file, open that file for
            * appending and make sure it's a 'normal'.
            */
           if (uap->path != NULL) {
                   NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, td);
                   flags = FWRITE | O_APPEND;
                   error = vn_open(&nd, &flags, 0, -1);
                   if (error)
                           goto done2;
                   NDFREE(&nd, NDF_ONLY_PNBUF);
   #ifdef MAC
                   error = mac_check_system_acct(td->td_ucred, nd.ni_vp);
                   if (error) {
                           vn_close(nd.ni_vp, flags, td->td_ucred, td);
                           goto done2;
                   }
   #endif
                   VOP_UNLOCK(nd.ni_vp, 0, td);
                   if (nd.ni_vp->v_type != VREG) {
                           vn_close(nd.ni_vp, flags, td->td_ucred, td);
                           error = EACCES;
                           goto done2;
                   }
   #ifdef MAC
           } else {
                   error = mac_check_system_acct(td->td_ucred, NULL);
                   if (error)
                           goto done2;
   #endif
           }
   
           /*
            * If accounting was previously enabled, kill the old space-watcher,
            * close the file, and (if no new file was specified, leave).
            */
   
           /*
            * XXX arr: Should not hold lock over vnode operation.
            */
   
           mtx_lock(&acct_mtx);
           if (acctp != NULLVP || savacctp != NULLVP) {
                   callout_stop(&acctwatch_callout);
                   error = vn_close((acctp != NULLVP ? acctp : savacctp),
                       (acctp != NULLVP ? acctflags : savacctflags),
                       (acctcred != NOCRED ? acctcred : savacctcred), td);
                   acctp = savacctp = NULLVP;
                   crfree(acctcred != NOCRED ? acctcred : savacctcred);
                   acctcred = savacctcred = NOCRED;
                   log(LOG_NOTICE, "Accounting disabled\n");
           }
           if (uap->path == NULL) {
                   mtx_unlock(&acct_mtx);
                   goto done2;
           }
   
           /*
            * Save the new accounting file vnode, and schedule the new
            * free space watcher.
            */
           acctp = nd.ni_vp;
           acctcred = crhold(td->td_ucred);
           acctflags = flags;
           callout_init(&acctwatch_callout, 0);
           mtx_unlock(&acct_mtx);
           log(LOG_NOTICE, "Accounting enabled\n");
           acctwatch(NULL);
   done2:
           mtx_unlock(&Giant);
           return (error);
   }
   
   /*
    * Write out process accounting information, on process exit.
    * Data to be written out is specified in Leffler, et al.
    * and are enumerated below.  (They're also noted in the system
    * "acct.h" header file.)
    */
   
   int
   acct_process(td)
           struct thread *td;
   {
           struct proc *p = td->td_proc;
           struct acct acct;
           struct rusage *r;
           struct timeval ut, st, tmp;
           int t, ret;
           struct vnode *vp;
           struct ucred *uc;
   
           mtx_lock(&acct_mtx);
   
           /* If accounting isn't enabled, don't bother */
           vp = acctp;
           if (vp == NULLVP) {
                   mtx_unlock(&acct_mtx);
                   return (0);
           }
   
           /*
            * Get process accounting information.
            */
   
           PROC_LOCK(p);
           /* (1) The name of the command that ran */
           bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
   
           /* (2) The amount of user and system time that was used */
           mtx_lock_spin(&sched_lock);
           calcru(p, &ut, &st, NULL);
           mtx_unlock_spin(&sched_lock);
           acct.ac_utime = encode_comp_t(ut.tv_sec, ut.tv_usec);
           acct.ac_stime = encode_comp_t(st.tv_sec, st.tv_usec);
   
           /* (3) The elapsed time the command ran (and its starting time) */
           tmp = boottime;
           timevaladd(&tmp, &p->p_stats->p_start);
           acct.ac_btime = tmp.tv_sec;
           microuptime(&tmp);
           timevalsub(&tmp, &p->p_stats->p_start);
           acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
   
           /* (4) The average amount of memory used */
           r = &p->p_stats->p_ru;
           tmp = ut;
           timevaladd(&tmp, &st);
           t = tmp.tv_sec * hz + tmp.tv_usec / tick;
           if (t)
                   acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
           else
                   acct.ac_mem = 0;
   
           /* (5) The number of disk I/O operations done */
           acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
   
           /* (6) The UID and GID of the process */
           acct.ac_uid = p->p_ucred->cr_ruid;
           acct.ac_gid = p->p_ucred->cr_rgid;
   
           /* (7) The terminal from which the process was started */
           SESS_LOCK(p->p_session);
           if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
                   acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
           else
                   acct.ac_tty = NOUDEV;
           SESS_UNLOCK(p->p_session);
   
           /* (8) The boolean flags that tell how the process terminated, etc. */
           acct.ac_flag = p->p_acflag;
           PROC_UNLOCK(p);
   
           /*
            * Write the accounting information to the file.
            */
           uc = crhold(acctcred);
           vref(vp);
           mtx_unlock(&acct_mtx);
   
           /*
            * Eliminate any file size rlimit.
            */
           if (p->p_limit->p_refcnt > 1) {
                   p->p_limit->p_refcnt--;
                   p->p_limit = limcopy(p->p_limit);
           }
           p->p_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
   
           VOP_LEASE(vp, td, uc, LEASE_WRITE);
           ret = vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
               (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, uc, NOCRED,
               (int *)0, td);
           vrele(vp);
           crfree(uc);
           return (ret);
   }
   
   /*
    * Encode_comp_t converts from ticks in seconds and microseconds
    * to ticks in 1/AHZ seconds.  The encoding is described in
    * Leffler, et al., on page 63.
    */
   
   #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(s, us)
           u_long s, us;
   {
           int exp, rnd;
   
           exp = 0;
           rnd = 0;
           s *= AHZ;
           s += us / (1000000 / AHZ);      /* Maximize precision. */
   
           while (s > MAXFRACT) {
           rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
                   s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
                   exp++;
           }
   
           /* If we need to round up, do it (and handle overflow correctly). */
           if (rnd && (++s > MAXFRACT)) {
                   s >>= EXPSIZE;
                   exp++;
           }
   
           /* Clean it up and polish it off. */
           exp <<= MANTSIZE;               /* Shift the exponent into place */
           exp += s;                       /* and add on the mantissa. */
           return (exp);
   }
   
   /*
    * Periodically check the filesystem to see if accounting
    * should be turned on or off.  Beware the case where the vnode
    * has been vgone()'d out from underneath us, e.g. when the file
    * system containing the accounting file has been forcibly unmounted.
    */
   /* ARGSUSED */
   static void
   acctwatch(a)
           void *a;
   {
           struct statfs sb;
   
           mtx_lock(&acct_mtx);
   
           /*
            * XXX arr: Need to fix the issue of holding acct_mtx over
            * the below vnode operations.
            */
   
           if (savacctp != NULLVP) {
                   if (savacctp->v_type == VBAD) {
                           (void) vn_close(savacctp, savacctflags, savacctcred,
                               NULL);
                           savacctp = NULLVP;
                           savacctcred = NOCRED;
                           mtx_unlock(&acct_mtx);
                           return;
                   }
                   (void)VFS_STATFS(savacctp->v_mount, &sb, (struct thread *)0);
                   if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
                           acctp = savacctp;
                           acctcred = savacctcred;
                           acctflags = savacctflags;
                           savacctp = NULLVP;
                           savacctcred = NOCRED;
                           log(LOG_NOTICE, "Accounting resumed\n");
                   }
           } else {
                   if (acctp == NULLVP) {
                           mtx_unlock(&acct_mtx);
                           return;
                   }
                   if (acctp->v_type == VBAD) {
                           (void) vn_close(acctp, acctflags, acctcred, NULL);
                           acctp = NULLVP;
                           crfree(acctcred);
                           acctcred = NOCRED;
                           mtx_unlock(&acct_mtx);
                           return;
                   }
                   (void)VFS_STATFS(acctp->v_mount, &sb, (struct thread *)0);
                   if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
                           savacctp = acctp;
                           savacctflags = acctflags;
                           savacctcred = acctcred;
                           acctp = NULLVP;
                           acctcred = NOCRED;
                           log(LOG_NOTICE, "Accounting suspended\n");
                   }
           }
           callout_reset(&acctwatch_callout, acctchkfreq * hz, acctwatch, NULL);
           mtx_unlock(&acct_mtx);
   }

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