security/seclvl.c

   1 /**
   2  * BSD Secure Levels LSM
   3  *
   4  * Maintainers:
   5  *      Michael A. Halcrow <mike@halcrow.us>
   6  *      Serge Hallyn <hallyn@cs.wm.edu>
   7  *
   8  * Copyright (c) 2001 WireX Communications, Inc <chris@wirex.com>
   9  * Copyright (c) 2001 Greg Kroah-Hartman <greg@kroah.com>
  10  * Copyright (c) 2002 International Business Machines <robb@austin.ibm.com>
  11  * Copyright (c) 2006 Davi E. M. Arnaut <davi.arnaut@gmail.com>
  12  *
  13  *      This program is free software; you can redistribute it and/or modify
  14  *      it under the terms of the GNU General Public License as published by
  15  *      the Free Software Foundation; either version 2 of the License, or
  16  *      (at your option) any later version.
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/kernel.h>
  22 #include <linux/init.h>
  23 #include <linux/security.h>
  24 #include <linux/netlink.h>
  25 #include <linux/fs.h>
  26 #include <linux/namei.h>
  27 #include <linux/mount.h>
  28 #include <linux/capability.h>
  29 #include <linux/time.h>
  30 #include <linux/proc_fs.h>
  31 #include <linux/kobject.h>
  32 #include <linux/crypto.h>
  33 #include <asm/scatterlist.h>
  34 #include <linux/scatterlist.h>
  35 #include <linux/gfp.h>
  36 #include <linux/sysfs.h>
  37
  38 #define SHA1_DIGEST_SIZE 20
  39
  40 /**
  41  * Module parameter that defines the initial secure level.
  42  *
  43  * When built as a module, it defaults to seclvl 1, which is the
  44  * behavior of BSD secure levels.  Note that this default behavior
  45  * wrecks havoc on a machine when the seclvl module is compiled into
  46  * the kernel.  In that case, we default to seclvl 0.
  47  */
  48 #ifdef CONFIG_SECURITY_SECLVL_MODULE
  49 static int initlvl = 1;
  50 #else
  51 static int initlvl;
  52 #endif
  53 module_param(initlvl, int, 0);
  54 MODULE_PARM_DESC(initlvl, "Initial secure level (defaults to 1)");
  55
  56 /* Module parameter that defines the verbosity level */
  57 static int verbosity;
  58 module_param(verbosity, int, 0);
  59 MODULE_PARM_DESC(verbosity, "Initial verbosity level (0 or 1; defaults to "
  60                  "0, which is Quiet)");
  61
  62 /**
  63  * Optional password which can be passed in to bring seclvl to 0
  64  * (i.e., for halt/reboot).  Defaults to NULL (the passwd attribute
  65  * file will not be registered in sysfs).
  66  *
  67  * This gets converted to its SHA1 hash when stored.  It's probably
  68  * not a good idea to use this parameter when loading seclvl from a
  69  * script; use sha1_passwd instead.
  70  */
  71
  72 #define MAX_PASSWD_SIZE 32
  73 static char passwd[MAX_PASSWD_SIZE];
  74 module_param_string(passwd, passwd, sizeof(passwd), 0);
  75 MODULE_PARM_DESC(passwd,
  76                  "Plaintext of password that sets seclvl=0 when written to "
  77                  "(sysfs mount point)/seclvl/passwd\n");
  78
  79 /**
  80  * SHA1 hashed version of the optional password which can be passed in
  81  * to bring seclvl to 0 (i.e., for halt/reboot).  Must be in
  82  * hexadecimal format (40 characters).  Defaults to NULL (the passwd
  83  * attribute file will not be registered in sysfs).
  84  *
  85  * Use the sha1sum utility to generate the SHA1 hash of a password:
  86  *
  87  * echo -n "secret" | sha1sum
  88  */
  89 #define MAX_SHA1_PASSWD 41
  90 static char sha1_passwd[MAX_SHA1_PASSWD];
  91 module_param_string(sha1_passwd, sha1_passwd, sizeof(sha1_passwd), 0);
  92 MODULE_PARM_DESC(sha1_passwd,
  93                  "SHA1 hash (40 hexadecimal characters) of password that "
  94                  "sets seclvl=0 when plaintext password is written to "
  95                  "(sysfs mount point)/seclvl/passwd\n");
  96
  97 static int hideHash = 1;
  98 module_param(hideHash, int, 0);
  99 MODULE_PARM_DESC(hideHash, "When set to 0, reading seclvl/passwd from sysfs "
 100                  "will return the SHA1-hashed value of the password that "
 101                  "lowers the secure level to 0.\n");
 102
 103 #define MY_NAME "seclvl"
 104
 105 /**
 106  * This time-limits log writes to one per second.
 107  */
 108 #define seclvl_printk(verb, type, fmt, arg...)                  \
 109         do {                                                    \
 110                 if (verbosity >= verb) {                        \
 111                         static unsigned long _prior;            \
 112                         unsigned long _now = jiffies;           \
 113                         if ((_now - _prior) > HZ) {             \
 114                                 printk(type "%s: %s: " fmt,     \
 115                                         MY_NAME, __FUNCTION__ , \
 116                                         ## arg);                \
 117                                 _prior = _now;                  \
 118                         }                                       \
 119                 }                                               \
 120         } while (0)
 121
 122 /**
 123  * The actual security level.  Ranges between -1 and 2 inclusive.
 124  */
 125 static int seclvl;
 126
 127 /**
 128  * flag to keep track of how we were registered
 129  */
 130 static int secondary;
 131
 132 /**
 133  * Verifies that the requested secure level is valid, given the current
 134  * secure level.
 135  */
 136 static int seclvl_sanity(int reqlvl)
 137 {
 138         if ((reqlvl < -1) || (reqlvl > 2)) {
 139                 seclvl_printk(1, KERN_WARNING, "Attempt to set seclvl out of "
 140                               "range: [%d]\n", reqlvl);
 141                 return -EINVAL;
 142         }
 143         if ((seclvl == 0) && (reqlvl == -1))
 144                 return 0;
 145         if (reqlvl < seclvl) {
 146                 seclvl_printk(1, KERN_WARNING, "Attempt to lower seclvl to "
 147                               "[%d]\n", reqlvl);
 148                 return -EPERM;
 149         }
 150         return 0;
 151 }
 152
 153 /**
 154  * security level advancement rules:
 155  *   Valid levels are -1 through 2, inclusive.
 156  *   From -1, stuck.  [ in case compiled into kernel ]
 157  *   From 0 or above, can only increment.
 158  */
 159 static void do_seclvl_advance(void *data, u64 val)
 160 {
 161         int ret;
 162         int newlvl = (int)val;
 163
 164         ret = seclvl_sanity(newlvl);
 165         if (ret)
 166                 return;
 167
 168         if (newlvl > 2) {
 169                 seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
 170                               "[%d]\n", newlvl);
 171                 return;
 172         }
 173         if (seclvl == -1) {
 174                 seclvl_printk(1, KERN_WARNING, "Not allowed to advance to "
 175                               "seclvl [%d]\n", seclvl);
 176                 return;
 177         }
 178         seclvl = newlvl;  /* would it be more "correct" to set *data? */
 179         return;
 180 }
 181
 182 static u64 seclvl_int_get(void *data)
 183 {
 184         return *(int *)data;
 185 }
 186
 187 DEFINE_SIMPLE_ATTRIBUTE(seclvl_file_ops, seclvl_int_get, do_seclvl_advance, "%lld\n");
 188
 189 static unsigned char hashedPassword[SHA1_DIGEST_SIZE];
 190
 191 /**
 192  * Converts a block of plaintext of into its SHA1 hashed value.
 193  *
 194  * It would be nice if crypto had a wrapper to do this for us linear
 195  * people...
 196  */
 197 static int
 198 plaintext_to_sha1(unsigned char *hash, const char *plaintext, unsigned int len)
 199 {
 200         struct crypto_tfm *tfm;
 201         struct scatterlist sg;
 202         if (len > PAGE_SIZE) {
 203                 seclvl_printk(0, KERN_ERR, "Plaintext password too large (%d "
 204                               "characters).  Largest possible is %lu "
 205                               "bytes.\n", len, PAGE_SIZE);
 206                 return -EINVAL;
 207         }
 208         tfm = crypto_alloc_tfm("sha1", CRYPTO_TFM_REQ_MAY_SLEEP);
 209         if (tfm == NULL) {
 210                 seclvl_printk(0, KERN_ERR,
 211                               "Failed to load transform for SHA1\n");
 212                 return -EINVAL;
 213         }
 214         sg_init_one(&sg, (u8 *)plaintext, len);
 215         crypto_digest_init(tfm);
 216         crypto_digest_update(tfm, &sg, 1);
 217         crypto_digest_final(tfm, hash);
 218         crypto_free_tfm(tfm);
 219         return 0;
 220 }
 221
 222 /**
 223  * Called whenever the user writes to the sysfs passwd handle to this kernel
 224  * object.  It hashes the password and compares the hashed results.
 225  */
 226 static ssize_t
 227 passwd_write_file(struct file * file, const char __user * buf,
 228                                 size_t count, loff_t *ppos)
 229 {
 230         char *p;
 231         int len;
 232         unsigned char tmp[SHA1_DIGEST_SIZE];
 233
 234         if (!*passwd && !*sha1_passwd) {
 235                 seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the "
 236                               "seclvl module, but neither a plain text "
 237                               "password nor a SHA1 hashed password was "
 238                               "passed in as a module parameter!  This is a "
 239                               "bug, since it should not be possible to be in "
 240                               "this part of the module; please tell a "
 241                               "maintainer about this event.\n");
 242                 return -EINVAL;
 243         }
 244
 245         if (count >= PAGE_SIZE)
 246                 return -EINVAL;
 247         if (*ppos != 0)
 248                 return -EINVAL;
 249         p = kmalloc(count, GFP_KERNEL);
 250         if (!p)
 251                 return -ENOMEM;
 252         len = -EFAULT;
 253         if (copy_from_user(p, buf, count))
 254                 goto out;
 255
 256         len = count;
 257         /* ``echo "secret" > seclvl/passwd'' includes a newline */
 258         if (p[len - 1] == '\n')
 259                 len--;
 260         /* Hash the password, then compare the hashed values */
 261         if ((len = plaintext_to_sha1(tmp, p, len))) {
 262                 seclvl_printk(0, KERN_ERR, "Error hashing password: rc = "
 263                               "[%d]\n", len);
 264                 goto out;
 265         }
 266
 267         len = -EPERM;
 268         if (memcmp(hashedPassword, tmp, SHA1_DIGEST_SIZE))
 269                 goto out;
 270
 271         seclvl_printk(0, KERN_INFO,
 272                       "Password accepted; seclvl reduced to 0.\n");
 273         seclvl = 0;
 274         len = count;
 275
 276 out:
 277         kfree (p);
 278         return len;
 279 }
 280
 281 static struct file_operations passwd_file_ops = {
 282         .write = passwd_write_file,
 283 };
 284
 285 /**
 286  * Explicitely disallow ptrace'ing the init process.
 287  */
 288 static int seclvl_ptrace(struct task_struct *parent, struct task_struct *child)
 289 {
 290         if (seclvl >= 0 && child->pid == 1) {
 291                 seclvl_printk(1, KERN_WARNING, "Attempt to ptrace "
 292                               "the init process dissallowed in "
 293                               "secure level %d\n", seclvl);
 294                 return -EPERM;
 295         }
 296         return 0;
 297 }
 298
 299 /**
 300  * Capability checks for seclvl.  The majority of the policy
 301  * enforcement for seclvl takes place here.
 302  */
 303 static int seclvl_capable(struct task_struct *tsk, int cap)
 304 {
 305         int rc = 0;
 306
 307         /* init can do anything it wants */
 308         if (tsk->pid == 1)
 309                 return 0;
 310
 311         if (seclvl > 0) {
 312                 rc = -EPERM;
 313
 314                 if (cap == CAP_LINUX_IMMUTABLE)
 315                         seclvl_printk(1, KERN_WARNING, "Attempt to modify "
 316                                       "the IMMUTABLE and/or APPEND extended "
 317                                       "attribute on a file with the IMMUTABLE "
 318                                       "and/or APPEND extended attribute set "
 319                                       "denied in seclvl [%d]\n", seclvl);
 320                 else if (cap == CAP_SYS_RAWIO)
 321                         seclvl_printk(1, KERN_WARNING, "Attempt to perform "
 322                                       "raw I/O while in secure level [%d] "
 323                                       "denied\n", seclvl);
 324                 else if (cap == CAP_NET_ADMIN)
 325                         seclvl_printk(1, KERN_WARNING, "Attempt to perform "
 326                                       "network administrative task while "
 327                                       "in secure level [%d] denied\n", seclvl);
 328                 else if (cap == CAP_SETUID)
 329                         seclvl_printk(1, KERN_WARNING, "Attempt to setuid "
 330                                       "while in secure level [%d] denied\n",
 331                                       seclvl);
 332                 else if (cap == CAP_SETGID)
 333                         seclvl_printk(1, KERN_WARNING, "Attempt to setgid "
 334                                       "while in secure level [%d] denied\n",
 335                                       seclvl);
 336                 else if (cap == CAP_SYS_MODULE)
 337                         seclvl_printk(1, KERN_WARNING, "Attempt to perform "
 338                                       "a module operation while in secure "
 339                                       "level [%d] denied\n", seclvl);
 340                 else
 341                         rc = 0;
 342         }
 343
 344         if (!rc) {
 345                 if (!(cap_is_fs_cap(cap) ? tsk->fsuid == 0 : tsk->euid == 0))
 346                         rc = -EPERM;
 347         }
 348
 349         if (rc)
 350                 seclvl_printk(1, KERN_WARNING, "Capability denied\n");
 351
 352         return rc;
 353 }
 354
 355 /**
 356  * Disallow reversing the clock in seclvl > 1
 357  */
 358 static int seclvl_settime(struct timespec *tv, struct timezone *tz)
 359 {
 360         if (tv && seclvl > 1) {
 361                 struct timespec now;
 362                 now = current_kernel_time();
 363                 if (tv->tv_sec < now.tv_sec ||
 364                     (tv->tv_sec == now.tv_sec && tv->tv_nsec < now.tv_nsec)) {
 365                         seclvl_printk(1, KERN_WARNING, "Attempt to decrement "
 366                                       "time in secure level %d denied: "
 367                                       "current->pid = [%d], "
 368                                       "current->group_leader->pid = [%d]\n",
 369                                       seclvl, current->pid,
 370                                       current->group_leader->pid);
 371                         return -EPERM;
 372                 }               /* if attempt to decrement time */
 373                 if (tv->tv_sec > 1924988400)    /* disallow dates after 2030) */
 374                         return -EPERM;          /* CVE-2005-4352 */
 375         }                       /* if seclvl > 1 */
 376         return 0;
 377 }
 378
 379 /* claim the blockdev to exclude mounters, release on file close */
 380 static int seclvl_bd_claim(struct inode *inode)
 381 {
 382         int holder;
 383         struct block_device *bdev = NULL;
 384         dev_t dev = inode->i_rdev;
 385         bdev = open_by_devnum(dev, FMODE_WRITE);
 386         if (bdev) {
 387                 if (bd_claim(bdev, &holder)) {
 388                         blkdev_put(bdev);
 389                         return -EPERM;
 390                 }
 391                 /* claimed, mark it to release on close */
 392                 inode->i_security = current;
 393         }
 394         return 0;
 395 }
 396
 397 /* release the blockdev if you claimed it */
 398 static void seclvl_bd_release(struct inode *inode)
 399 {
 400         if (inode && S_ISBLK(inode->i_mode) && inode->i_security == current) {
 401                 struct block_device *bdev = inode->i_bdev;
 402                 if (bdev) {
 403                         bd_release(bdev);
 404                         blkdev_put(bdev);
 405                         inode->i_security = NULL;
 406                 }
 407         }
 408 }
 409
 410 /**
 411  * Security for writes to block devices is regulated by this seclvl
 412  * function.  Deny all writes to block devices in seclvl 2.  In
 413  * seclvl 1, we only deny writes to *mounted* block devices.
 414  */
 415 static int
 416 seclvl_inode_permission(struct inode *inode, int mask, struct nameidata *nd)
 417 {
 418         if (current->pid != 1 && S_ISBLK(inode->i_mode) && (mask & MAY_WRITE)) {
 419                 switch (seclvl) {
 420                 case 2:
 421                         seclvl_printk(1, KERN_WARNING, "Write to block device "
 422                                       "denied in secure level [%d]\n", seclvl);
 423                         return -EPERM;
 424                 case 1:
 425                         if (seclvl_bd_claim(inode)) {
 426                                 seclvl_printk(1, KERN_WARNING,
 427                                               "Write to mounted block device "
 428                                               "denied in secure level [%d]\n",
 429                                               seclvl);
 430                                 return -EPERM;
 431                         }
 432                 }
 433         }
 434         return 0;
 435 }
 436
 437 /**
 438  * The SUID and SGID bits cannot be set in seclvl >= 1
 439  */
 440 static int seclvl_inode_setattr(struct dentry *dentry, struct iattr *iattr)
 441 {
 442         if (seclvl > 0) {
 443                 if (iattr->ia_valid & ATTR_MODE)
 444                         if (iattr->ia_mode & S_ISUID ||
 445                             iattr->ia_mode & S_ISGID) {
 446                                 seclvl_printk(1, KERN_WARNING, "Attempt to "
 447                                               "modify SUID or SGID bit "
 448                                               "denied in seclvl [%d]\n",
 449                                               seclvl);
 450                                 return -EPERM;
 451                         }
 452         }
 453         return 0;
 454 }
 455
 456 /* release busied block devices */
 457 static void seclvl_file_free_security(struct file *filp)
 458 {
 459         struct dentry *dentry = filp->f_dentry;
 460
 461         if (dentry)
 462                 seclvl_bd_release(dentry->d_inode);
 463 }
 464
 465 /**
 466  * Cannot unmount in secure level 2
 467  */
 468 static int seclvl_umount(struct vfsmount *mnt, int flags)
 469 {
 470         if (current->pid != 1 && seclvl == 2) {
 471                 seclvl_printk(1, KERN_WARNING, "Attempt to unmount in secure "
 472                               "level %d\n", seclvl);
 473                 return -EPERM;
 474         }
 475         return 0;
 476 }
 477
 478 static struct security_operations seclvl_ops = {
 479         .ptrace = seclvl_ptrace,
 480         .capable = seclvl_capable,
 481         .inode_permission = seclvl_inode_permission,
 482         .inode_setattr = seclvl_inode_setattr,
 483         .file_free_security = seclvl_file_free_security,
 484         .settime = seclvl_settime,
 485         .sb_umount = seclvl_umount,
 486 };
 487
 488 /**
 489  * Process the password-related module parameters
 490  */
 491 static int processPassword(void)
 492 {
 493         int rc = 0;
 494         if (*passwd) {
 495                 char *p;
 496
 497                 if (*sha1_passwd) {
 498                         seclvl_printk(0, KERN_ERR, "Error: Both "
 499                                       "passwd and sha1_passwd "
 500                                       "were set, but they are mutually "
 501                                       "exclusive.\n");
 502                         return -EINVAL;
 503                 }
 504
 505                 p = kstrdup(passwd, GFP_KERNEL);
 506                 if (p == NULL)
 507                         return -ENOMEM;
 508
 509                 if ((rc = plaintext_to_sha1(hashedPassword, p, strlen(p))))
 510                         seclvl_printk(0, KERN_ERR, "Error: SHA1 support not "
 511                                       "in kernel\n");
 512
 513                 kfree (p);
 514                 /* All static data goes to the BSS, which zero's the
 515                  * plaintext password out for us. */
 516         } else if (*sha1_passwd) {      // Base 16
 517                 int i;
 518                 i = strlen(sha1_passwd);
 519                 if (i != (SHA1_DIGEST_SIZE * 2)) {
 520                         seclvl_printk(0, KERN_ERR, "Received [%d] bytes; "
 521                                       "expected [%d] for the hexadecimal "
 522                                       "representation of the SHA1 hash of "
 523                                       "the password.\n",
 524                                       i, (SHA1_DIGEST_SIZE * 2));
 525                         return -EINVAL;
 526                 }
 527                 while ((i -= 2) + 2) {
 528                         unsigned char tmp;
 529                         tmp = sha1_passwd[i + 2];
 530                         sha1_passwd[i + 2] = '\0';
 531                         hashedPassword[i / 2] = (unsigned char)
 532                             simple_strtol(&sha1_passwd[i], NULL, 16);
 533                         sha1_passwd[i + 2] = tmp;
 534                 }
 535         }
 536         return rc;
 537 }
 538
 539 /**
 540  * securityfs registrations
 541  */
 542 struct dentry *dir_ino, *seclvl_ino, *passwd_ino;
 543
 544 static int seclvlfs_register(void)
 545 {
 546         int rc = 0;
 547
 548         dir_ino = securityfs_create_dir("seclvl", NULL);
 549
 550         if (IS_ERR(dir_ino))
 551                 return PTR_ERR(dir_ino);
 552
 553         seclvl_ino = securityfs_create_file("seclvl", S_IRUGO | S_IWUSR,
 554                                 dir_ino, &seclvl, &seclvl_file_ops);
 555         if (IS_ERR(seclvl_ino)) {
 556                 rc = PTR_ERR(seclvl_ino);
 557                 goto out_deldir;
 558         }
 559         if (*passwd || *sha1_passwd) {
 560                 passwd_ino = securityfs_create_file("passwd", S_IRUGO | S_IWUSR,
 561                                 dir_ino, NULL, &passwd_file_ops);
 562                 if (IS_ERR(passwd_ino)) {
 563                         rc = PTR_ERR(passwd_ino);
 564                         goto out_delf;
 565                 }
 566         }
 567         return rc;
 568
 569 out_delf:
 570         securityfs_remove(seclvl_ino);
 571
 572 out_deldir:
 573         securityfs_remove(dir_ino);
 574
 575         return rc;
 576 }
 577
 578 static void seclvlfs_unregister(void)
 579 {
 580         securityfs_remove(seclvl_ino);
 581
 582         if (*passwd || *sha1_passwd)
 583                 securityfs_remove(passwd_ino);
 584
 585         securityfs_remove(dir_ino);
 586 }
 587
 588 /**
 589  * Initialize the seclvl module.
 590  */
 591 static int __init seclvl_init(void)
 592 {
 593         int rc = 0;
 594         static char once;
 595
 596         if (verbosity < 0 || verbosity > 1) {
 597                 printk(KERN_ERR "Error: bad verbosity [%d]; only 0 or 1 "
 598                        "are valid values\n", verbosity);
 599                 rc = -EINVAL;
 600                 goto exit;
 601         }
 602         if (initlvl < -1 || initlvl > 2) {
 603                 seclvl_printk(0, KERN_ERR, "Error: bad initial securelevel "
 604                               "[%d].\n", initlvl);
 605                 rc = -EINVAL;
 606                 goto exit;
 607         }
 608         seclvl = initlvl;
 609         if ((rc = processPassword())) {
 610                 seclvl_printk(0, KERN_ERR, "Error processing the password "
 611                               "module parameter(s): rc = [%d]\n", rc);
 612                 goto exit;
 613         }
 614
 615         if ((rc = seclvlfs_register())) {
 616                 seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
 617                 goto exit;
 618         }
 619         /* register ourselves with the security framework */
 620         if (register_security(&seclvl_ops)) {
 621                 seclvl_printk(0, KERN_ERR,
 622                               "seclvl: Failure registering with the "
 623                               "kernel.\n");
 624                 /* try registering with primary module */
 625                 rc = mod_reg_security(MY_NAME, &seclvl_ops);
 626                 if (rc) {
 627                         seclvl_printk(0, KERN_ERR, "seclvl: Failure "
 628                                       "registering with primary security "
 629                                       "module.\n");
 630                         seclvlfs_unregister();
 631                         goto exit;
 632                 }               /* if primary module registered */
 633                 secondary = 1;
 634         }                       /* if we registered ourselves with the security framework */
 635
 636         seclvl_printk(0, KERN_INFO, "seclvl: Successfully initialized.\n");
 637
 638         if (once) {
 639                 once = 1;
 640                 seclvl_printk(0, KERN_INFO, "seclvl is going away. It has been "
 641                                 "buggy for ages. Also, be warned that "
 642                                 "Securelevels are useless.");
 643         }
 644  exit:
 645         if (rc)
 646                 printk(KERN_ERR "seclvl: Error during initialization: rc = "
 647                        "[%d]\n", rc);
 648         return rc;
 649 }
 650
 651 /**
 652  * Remove the seclvl module.
 653  */
 654 static void __exit seclvl_exit(void)
 655 {
 656         seclvlfs_unregister();
 657
 658         if (secondary)
 659                 mod_unreg_security(MY_NAME, &seclvl_ops);
 660         else if (unregister_security(&seclvl_ops))
 661                 seclvl_printk(0, KERN_INFO,
 662                               "seclvl: Failure unregistering with the "
 663                               "kernel\n");
 664 }
 665
 666 module_init(seclvl_init);
 667 module_exit(seclvl_exit);
 668
 669 MODULE_AUTHOR("Michael A. Halcrow <mike@halcrow.us>");
 670 MODULE_DESCRIPTION("LSM implementation of the BSD Secure Levels");
 671 MODULE_LICENSE("GPL");