kernel/acct.c

   1 /*
   2  *  linux/kernel/acct.c
   3  *
   4  *  BSD Process Accounting for Linux
   5  *
   6  *  Author: Marco van Wieringen <mvw@planets.elm.net>
   7  *
   8  *  Some code based on ideas and code from:
   9  *  Thomas K. Dyas <tdyas@eden.rutgers.edu>
  10  *
  11  *  This file implements BSD-style process accounting. Whenever any
  12  *  process exits, an accounting record of type "struct acct" is
  13  *  written to the file specified with the acct() system call. It is
  14  *  up to user-level programs to do useful things with the accounting
  15  *  log. The kernel just provides the raw accounting information.
  16  *
  17  * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
  18  *
  19  *  Plugged two leaks. 1) It didn't return acct_file into the free_filps if
  20  *  the file happened to be read-only. 2) If the accounting was suspended
  21  *  due to the lack of space it happily allowed to reopen it and completely
  22  *  lost the old acct_file. 3/10/98, Al Viro.
  23  *
  24  *  Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
  25  *  XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
  26  *
  27  *  Fixed a nasty interaction with with sys_umount(). If the accointing
  28  *  was suspeneded we failed to stop it on umount(). Messy.
  29  *  Another one: remount to readonly didn't stop accounting.
  30  *      Question: what should we do if we have CAP_SYS_ADMIN but not
  31  *  CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
  32  *  unless we are messing with the root. In that case we are getting a
  33  *  real mess with do_remount_sb(). 9/11/98, AV.
  34  *
  35  *  Fixed a bunch of races (and pair of leaks). Probably not the best way,
  36  *  but this one obviously doesn't introduce deadlocks. Later. BTW, found
  37  *  one race (and leak) in BSD implementation.
  38  *  OK, that's better. ANOTHER race and leak in BSD variant. There always
  39  *  is one more bug... 10/11/98, AV.
  40  *
  41  *      Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
  42  * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
  43  * a struct file opened for write. Fixed. 2/6/2000, AV.
  44  */
  45
  46 #include <linux/config.h>
  47 #include <linux/mm.h>
  48 #include <linux/slab.h>
  49 #include <linux/acct.h>
  50 #include <linux/file.h>
  51 #include <linux/tty.h>
  52 #include <linux/security.h>
  53 #include <linux/vfs.h>
  54 #include <linux/jiffies.h>
  55 #include <linux/times.h>
  56 #include <linux/syscalls.h>
  57 #include <linux/mount.h>
  58 #include <asm/uaccess.h>
  59 #include <asm/div64.h>
  60 #include <linux/blkdev.h> /* sector_div */
  61
  62 /*
  63  * These constants control the amount of freespace that suspend and
  64  * resume the process accounting system, and the time delay between
  65  * each check.
  66  * Turned into sysctl-controllable parameters. AV, 12/11/98
  67  */
  68
  69 int acct_parm[3] = {4, 2, 30};
  70 #define RESUME          (acct_parm[0])  /* >foo% free space - resume */
  71 #define SUSPEND         (acct_parm[1])  /* <foo% free space - suspend */
  72 #define ACCT_TIMEOUT    (acct_parm[2])  /* foo second timeout between checks */
  73
  74 /*
  75  * External references and all of the globals.
  76  */
  77 static void do_acct_process(long, struct file *);
  78
  79 /*
  80  * This structure is used so that all the data protected by lock
  81  * can be placed in the same cache line as the lock.  This primes
  82  * the cache line to have the data after getting the lock.
  83  */
  84 struct acct_glbs {
  85         spinlock_t              lock;
  86         volatile int            active;
  87         volatile int            needcheck;
  88         struct file             *file;
  89         struct timer_list       timer;
  90 };
  91
  92 static struct acct_glbs acct_globals __cacheline_aligned = {SPIN_LOCK_UNLOCKED};
  93
  94 /*
  95  * Called whenever the timer says to check the free space.
  96  */
  97 static void acct_timeout(unsigned long unused)
  98 {
  99         acct_globals.needcheck = 1;
 100 }
 101
 102 /*
 103  * Check the amount of free space and suspend/resume accordingly.
 104  */
 105 static int check_free_space(struct file *file)
 106 {
 107         struct kstatfs sbuf;
 108         int res;
 109         int act;
 110         sector_t resume;
 111         sector_t suspend;
 112
 113         spin_lock(&acct_globals.lock);
 114         res = acct_globals.active;
 115         if (!file || !acct_globals.needcheck)
 116                 goto out;
 117         spin_unlock(&acct_globals.lock);
 118
 119         /* May block */
 120         if (vfs_statfs(file->f_dentry->d_inode->i_sb, &sbuf))
 121                 return res;
 122         suspend = sbuf.f_blocks * SUSPEND;
 123         resume = sbuf.f_blocks * RESUME;
 124
 125         sector_div(suspend, 100);
 126         sector_div(resume, 100);
 127
 128         if (sbuf.f_bavail <= suspend)
 129                 act = -1;
 130         else if (sbuf.f_bavail >= resume)
 131                 act = 1;
 132         else
 133                 act = 0;
 134
 135         /*
 136          * If some joker switched acct_globals.file under us we'ld better be
 137          * silent and _not_ touch anything.
 138          */
 139         spin_lock(&acct_globals.lock);
 140         if (file != acct_globals.file) {
 141                 if (act)
 142                         res = act>0;
 143                 goto out;
 144         }
 145
 146         if (acct_globals.active) {
 147                 if (act < 0) {
 148                         acct_globals.active = 0;
 149                         printk(KERN_INFO "Process accounting paused\n");
 150                 }
 151         } else {
 152                 if (act > 0) {
 153                         acct_globals.active = 1;
 154                         printk(KERN_INFO "Process accounting resumed\n");
 155                 }
 156         }
 157
 158         del_timer(&acct_globals.timer);
 159         acct_globals.needcheck = 0;
 160         acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
 161         add_timer(&acct_globals.timer);
 162         res = acct_globals.active;
 163 out:
 164         spin_unlock(&acct_globals.lock);
 165         return res;
 166 }
 167
 168 /*
 169  * Close the old accounting file (if currently open) and then replace
 170  * it with file (if non-NULL).
 171  *
 172  * NOTE: acct_globals.lock MUST be held on entry and exit.
 173  */
 174 static void acct_file_reopen(struct file *file)
 175 {
 176         struct file *old_acct = NULL;
 177
 178         if (acct_globals.file) {
 179                 old_acct = acct_globals.file;
 180                 del_timer(&acct_globals.timer);
 181                 acct_globals.active = 0;
 182                 acct_globals.needcheck = 0;
 183                 acct_globals.file = NULL;
 184         }
 185         if (file) {
 186                 acct_globals.file = file;
 187                 acct_globals.needcheck = 0;
 188                 acct_globals.active = 1;
 189                 /* It's been deleted if it was used before so this is safe */
 190                 init_timer(&acct_globals.timer);
 191                 acct_globals.timer.function = acct_timeout;
 192                 acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
 193                 add_timer(&acct_globals.timer);
 194         }
 195         if (old_acct) {
 196                 mnt_unpin(old_acct->f_vfsmnt);
 197                 spin_unlock(&acct_globals.lock);
 198                 do_acct_process(0, old_acct);
 199                 filp_close(old_acct, NULL);
 200                 spin_lock(&acct_globals.lock);
 201         }
 202 }
 203
 204 static int acct_on(char *name)
 205 {
 206         struct file *file;
 207         int error;
 208
 209         /* Difference from BSD - they don't do O_APPEND */
 210         file = filp_open(name, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
 211         if (IS_ERR(file))
 212                 return PTR_ERR(file);
 213
 214         if (!S_ISREG(file->f_dentry->d_inode->i_mode)) {
 215                 filp_close(file, NULL);
 216                 return -EACCES;
 217         }
 218
 219         if (!file->f_op->write) {
 220                 filp_close(file, NULL);
 221                 return -EIO;
 222         }
 223
 224         error = security_acct(file);
 225         if (error) {
 226                 filp_close(file, NULL);
 227                 return error;
 228         }
 229
 230         spin_lock(&acct_globals.lock);
 231         mnt_pin(file->f_vfsmnt);
 232         acct_file_reopen(file);
 233         spin_unlock(&acct_globals.lock);
 234
 235         mntput(file->f_vfsmnt); /* it's pinned, now give up active reference */
 236
 237         return 0;
 238 }
 239
 240 /**
 241  * sys_acct - enable/disable process accounting
 242  * @name: file name for accounting records or NULL to shutdown accounting
 243  *
 244  * Returns 0 for success or negative errno values for failure.
 245  *
 246  * sys_acct() is the only system call needed to implement process
 247  * accounting. It takes the name of the file where accounting records
 248  * should be written. If the filename is NULL, accounting will be
 249  * shutdown.
 250  */
 251 asmlinkage long sys_acct(const char __user *name)
 252 {
 253         int error;
 254
 255         if (!capable(CAP_SYS_PACCT))
 256                 return -EPERM;
 257
 258         if (name) {
 259                 char *tmp = getname(name);
 260                 if (IS_ERR(tmp))
 261                         return (PTR_ERR(tmp));
 262                 error = acct_on(tmp);
 263                 putname(tmp);
 264         } else {
 265                 error = security_acct(NULL);
 266                 if (!error) {
 267                         spin_lock(&acct_globals.lock);
 268                         acct_file_reopen(NULL);
 269                         spin_unlock(&acct_globals.lock);
 270                 }
 271         }
 272         return error;
 273 }
 274
 275 /**
 276  * acct_auto_close - turn off a filesystem's accounting if it is on
 277  * @m: vfsmount being shut down
 278  *
 279  * If the accounting is turned on for a file in the subtree pointed to
 280  * to by m, turn accounting off.  Done when m is about to die.
 281  */
 282 void acct_auto_close_mnt(struct vfsmount *m)
 283 {
 284         spin_lock(&acct_globals.lock);
 285         if (acct_globals.file && acct_globals.file->f_vfsmnt == m)
 286                 acct_file_reopen(NULL);
 287         spin_unlock(&acct_globals.lock);
 288 }
 289
 290 /**
 291  * acct_auto_close - turn off a filesystem's accounting if it is on
 292  * @sb: super block for the filesystem
 293  *
 294  * If the accounting is turned on for a file in the filesystem pointed
 295  * to by sb, turn accounting off.
 296  */
 297 void acct_auto_close(struct super_block *sb)
 298 {
 299         spin_lock(&acct_globals.lock);
 300         if (acct_globals.file &&
 301             acct_globals.file->f_vfsmnt->mnt_sb == sb) {
 302                 acct_file_reopen(NULL);
 303         }
 304         spin_unlock(&acct_globals.lock);
 305 }
 306
 307 /*
 308  *  encode an unsigned long into a comp_t
 309  *
 310  *  This routine has been adopted from the encode_comp_t() function in
 311  *  the kern_acct.c file of the FreeBSD operating system. The encoding
 312  *  is a 13-bit fraction with a 3-bit (base 8) exponent.
 313  */
 314
 315 #define MANTSIZE        13                      /* 13 bit mantissa. */
 316 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
 317 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
 318
 319 static comp_t encode_comp_t(unsigned long value)
 320 {
 321         int exp, rnd;
 322
 323         exp = rnd = 0;
 324         while (value > MAXFRACT) {
 325                 rnd = value & (1 << (EXPSIZE - 1));     /* Round up? */
 326                 value >>= EXPSIZE;      /* Base 8 exponent == 3 bit shift. */
 327                 exp++;
 328         }
 329
 330         /*
 331          * If we need to round up, do it (and handle overflow correctly).
 332          */
 333         if (rnd && (++value > MAXFRACT)) {
 334                 value >>= EXPSIZE;
 335                 exp++;
 336         }
 337
 338         /*
 339          * Clean it up and polish it off.
 340          */
 341         exp <<= MANTSIZE;               /* Shift the exponent into place */
 342         exp += value;                   /* and add on the mantissa. */
 343         return exp;
 344 }
 345
 346 #if ACCT_VERSION==1 || ACCT_VERSION==2
 347 /*
 348  * encode an u64 into a comp2_t (24 bits)
 349  *
 350  * Format: 5 bit base 2 exponent, 20 bits mantissa.
 351  * The leading bit of the mantissa is not stored, but implied for
 352  * non-zero exponents.
 353  * Largest encodable value is 50 bits.
 354  */
 355
 356 #define MANTSIZE2       20                      /* 20 bit mantissa. */
 357 #define EXPSIZE2        5                       /* 5 bit base 2 exponent. */
 358 #define MAXFRACT2       ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
 359 #define MAXEXP2         ((1 <<EXPSIZE2) - 1)    /* Maximum exponent. */
 360
 361 static comp2_t encode_comp2_t(u64 value)
 362 {
 363         int exp, rnd;
 364
 365         exp = (value > (MAXFRACT2>>1));
 366         rnd = 0;
 367         while (value > MAXFRACT2) {
 368                 rnd = value & 1;
 369                 value >>= 1;
 370                 exp++;
 371         }
 372
 373         /*
 374          * If we need to round up, do it (and handle overflow correctly).
 375          */
 376         if (rnd && (++value > MAXFRACT2)) {
 377                 value >>= 1;
 378                 exp++;
 379         }
 380
 381         if (exp > MAXEXP2) {
 382                 /* Overflow. Return largest representable number instead. */
 383                 return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
 384         } else {
 385                 return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
 386         }
 387 }
 388 #endif
 389
 390 #if ACCT_VERSION==3
 391 /*
 392  * encode an u64 into a 32 bit IEEE float
 393  */
 394 static u32 encode_float(u64 value)
 395 {
 396         unsigned exp = 190;
 397         unsigned u;
 398
 399         if (value==0) return 0;
 400         while ((s64)value > 0){
 401                 value <<= 1;
 402                 exp--;
 403         }
 404         u = (u32)(value >> 40) & 0x7fffffu;
 405         return u | (exp << 23);
 406 }
 407 #endif
 408
 409 /*
 410  *  Write an accounting entry for an exiting process
 411  *
 412  *  The acct_process() call is the workhorse of the process
 413  *  accounting system. The struct acct is built here and then written
 414  *  into the accounting file. This function should only be called from
 415  *  do_exit().
 416  */
 417
 418 /*
 419  *  do_acct_process does all actual work. Caller holds the reference to file.
 420  */
 421 static void do_acct_process(long exitcode, struct file *file)
 422 {
 423         acct_t ac;
 424         mm_segment_t fs;
 425         unsigned long vsize;
 426         unsigned long flim;
 427         u64 elapsed;
 428         u64 run_time;
 429         struct timespec uptime;
 430
 431         /*
 432          * First check to see if there is enough free_space to continue
 433          * the process accounting system.
 434          */
 435         if (!check_free_space(file))
 436                 return;
 437
 438         /*
 439          * Fill the accounting struct with the needed info as recorded
 440          * by the different kernel functions.
 441          */
 442         memset((caddr_t)&ac, 0, sizeof(acct_t));
 443
 444         ac.ac_version = ACCT_VERSION | ACCT_BYTEORDER;
 445         strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));
 446
 447         /* calculate run_time in nsec*/
 448         do_posix_clock_monotonic_gettime(&uptime);
 449         run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
 450         run_time -= (u64)current->start_time.tv_sec*NSEC_PER_SEC
 451                                         + current->start_time.tv_nsec;
 452         /* convert nsec -> AHZ */
 453         elapsed = nsec_to_AHZ(run_time);
 454 #if ACCT_VERSION==3
 455         ac.ac_etime = encode_float(elapsed);
 456 #else
 457         ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
 458                                (unsigned long) elapsed : (unsigned long) -1l);
 459 #endif
 460 #if ACCT_VERSION==1 || ACCT_VERSION==2
 461         {
 462                 /* new enlarged etime field */
 463                 comp2_t etime = encode_comp2_t(elapsed);
 464                 ac.ac_etime_hi = etime >> 16;
 465                 ac.ac_etime_lo = (u16) etime;
 466         }
 467 #endif
 468         do_div(elapsed, AHZ);
 469         ac.ac_btime = xtime.tv_sec - elapsed;
 470         ac.ac_utime = encode_comp_t(jiffies_to_AHZ(
 471                                             current->signal->utime +
 472                                             current->group_leader->utime));
 473         ac.ac_stime = encode_comp_t(jiffies_to_AHZ(
 474                                             current->signal->stime +
 475                                             current->group_leader->stime));
 476         /* we really need to bite the bullet and change layout */
 477         ac.ac_uid = current->uid;
 478         ac.ac_gid = current->gid;
 479 #if ACCT_VERSION==2
 480         ac.ac_ahz = AHZ;
 481 #endif
 482 #if ACCT_VERSION==1 || ACCT_VERSION==2
 483         /* backward-compatible 16 bit fields */
 484         ac.ac_uid16 = current->uid;
 485         ac.ac_gid16 = current->gid;
 486 #endif
 487 #if ACCT_VERSION==3
 488         ac.ac_pid = current->tgid;
 489         ac.ac_ppid = current->parent->tgid;
 490 #endif
 491
 492         read_lock(&tasklist_lock);      /* pin current->signal */
 493         ac.ac_tty = current->signal->tty ?
 494                 old_encode_dev(tty_devnum(current->signal->tty)) : 0;
 495         read_unlock(&tasklist_lock);
 496
 497         ac.ac_flag = 0;
 498         if (current->flags & PF_FORKNOEXEC)
 499                 ac.ac_flag |= AFORK;
 500         if (current->flags & PF_SUPERPRIV)
 501                 ac.ac_flag |= ASU;
 502         if (current->flags & PF_DUMPCORE)
 503                 ac.ac_flag |= ACORE;
 504         if (current->flags & PF_SIGNALED)
 505                 ac.ac_flag |= AXSIG;
 506
 507         vsize = 0;
 508         if (current->mm) {
 509                 struct vm_area_struct *vma;
 510                 down_read(&current->mm->mmap_sem);
 511                 vma = current->mm->mmap;
 512                 while (vma) {
 513                         vsize += vma->vm_end - vma->vm_start;
 514                         vma = vma->vm_next;
 515                 }
 516                 up_read(&current->mm->mmap_sem);
 517         }
 518         vsize = vsize / 1024;
 519         ac.ac_mem = encode_comp_t(vsize);
 520         ac.ac_io = encode_comp_t(0 /* current->io_usage */);    /* %% */
 521         ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
 522         ac.ac_minflt = encode_comp_t(current->signal->min_flt +
 523                                      current->group_leader->min_flt);
 524         ac.ac_majflt = encode_comp_t(current->signal->maj_flt +
 525                                      current->group_leader->maj_flt);
 526         ac.ac_swaps = encode_comp_t(0);
 527         ac.ac_exitcode = exitcode;
 528
 529         /*
 530          * Kernel segment override to datasegment and write it
 531          * to the accounting file.
 532          */
 533         fs = get_fs();
 534         set_fs(KERNEL_DS);
 535         /*
 536          * Accounting records are not subject to resource limits.
 537          */
 538         flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
 539         current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
 540         file->f_op->write(file, (char *)&ac,
 541                                sizeof(acct_t), &file->f_pos);
 542         current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
 543         set_fs(fs);
 544 }
 545
 546 /**
 547  * acct_process - now just a wrapper around do_acct_process
 548  * @exitcode: task exit code
 549  *
 550  * handles process accounting for an exiting task
 551  */
 552 void acct_process(long exitcode)
 553 {
 554         struct file *file = NULL;
 555
 556         /*
 557          * accelerate the common fastpath:
 558          */
 559         if (!acct_globals.file)
 560                 return;
 561
 562         spin_lock(&acct_globals.lock);
 563         file = acct_globals.file;
 564         if (unlikely(!file)) {
 565                 spin_unlock(&acct_globals.lock);
 566                 return;
 567         }
 568         get_file(file);
 569         spin_unlock(&acct_globals.lock);
 570
 571         do_acct_process(exitcode, file);
 572         fput(file);
 573 }
 574
 575
 576 /**
 577  * acct_update_integrals - update mm integral fields in task_struct
 578  * @tsk: task_struct for accounting
 579  */
 580 void acct_update_integrals(struct task_struct *tsk)
 581 {
 582         if (likely(tsk->mm)) {
 583                 long delta = tsk->stime - tsk->acct_stimexpd;
 584
 585                 if (delta == 0)
 586                         return;
 587                 tsk->acct_stimexpd = tsk->stime;
 588                 tsk->acct_rss_mem1 += delta * get_mm_rss(tsk->mm);
 589                 tsk->acct_vm_mem1 += delta * tsk->mm->total_vm;
 590         }
 591 }
 592
 593 /**
 594  * acct_clear_integrals - clear the mm integral fields in task_struct
 595  * @tsk: task_struct whose accounting fields are cleared
 596  */
 597 void acct_clear_integrals(struct task_struct *tsk)
 598 {
 599         if (tsk) {
 600                 tsk->acct_stimexpd = 0;
 601                 tsk->acct_rss_mem1 = 0;
 602                 tsk->acct_vm_mem1 = 0;
 603         }
 604 }