security/tomoyo/domain.c

   1 /*
   2  * security/tomoyo/domain.c
   3  *
   4  * Implementation of the Domain-Based Mandatory Access Control.
   5  *
   6  * Copyright (C) 2005-2009  NTT DATA CORPORATION
   7  *
   8  * Version: 2.2.0   2009/04/01
   9  *
  10  */
  11
  12 #include "common.h"
  13 #include <linux/binfmts.h>
  14 #include <linux/slab.h>
  15
  16 /* Variables definitions.*/
  17
  18 /* The initial domain. */
  19 struct tomoyo_domain_info tomoyo_kernel_domain;
  20
  21 /*
  22  * tomoyo_domain_list is used for holding list of domains.
  23  * The ->acl_info_list of "struct tomoyo_domain_info" is used for holding
  24  * permissions (e.g. "allow_read /lib/libc-2.5.so") given to each domain.
  25  *
  26  * An entry is added by
  27  *
  28  * # ( echo "<kernel>"; echo "allow_execute /sbin/init" ) > \
  29  *                                  /sys/kernel/security/tomoyo/domain_policy
  30  *
  31  * and is deleted by
  32  *
  33  * # ( echo "<kernel>"; echo "delete allow_execute /sbin/init" ) > \
  34  *                                  /sys/kernel/security/tomoyo/domain_policy
  35  *
  36  * and all entries are retrieved by
  37  *
  38  * # cat /sys/kernel/security/tomoyo/domain_policy
  39  *
  40  * A domain is added by
  41  *
  42  * # echo "<kernel>" > /sys/kernel/security/tomoyo/domain_policy
  43  *
  44  * and is deleted by
  45  *
  46  * # echo "delete <kernel>" > /sys/kernel/security/tomoyo/domain_policy
  47  *
  48  * and all domains are retrieved by
  49  *
  50  * # grep '^<kernel>' /sys/kernel/security/tomoyo/domain_policy
  51  *
  52  * Normally, a domainname is monotonically getting longer because a domainname
  53  * which the process will belong to if an execve() operation succeeds is
  54  * defined as a concatenation of "current domainname" + "pathname passed to
  55  * execve()".
  56  * See tomoyo_domain_initializer_list and tomoyo_domain_keeper_list for
  57  * exceptions.
  58  */
  59 LIST_HEAD(tomoyo_domain_list);
  60
  61 /**
  62  * tomoyo_get_last_name - Get last component of a domainname.
  63  *
  64  * @domain: Pointer to "struct tomoyo_domain_info".
  65  *
  66  * Returns the last component of the domainname.
  67  */
  68 const char *tomoyo_get_last_name(const struct tomoyo_domain_info *domain)
  69 {
  70         const char *cp0 = domain->domainname->name;
  71         const char *cp1 = strrchr(cp0, ' ');
  72
  73         if (cp1)
  74                 return cp1 + 1;
  75         return cp0;
  76 }
  77
  78 /*
  79  * tomoyo_domain_initializer_list is used for holding list of programs which
  80  * triggers reinitialization of domainname. Normally, a domainname is
  81  * monotonically getting longer. But sometimes, we restart daemon programs.
  82  * It would be convenient for us that "a daemon started upon system boot" and
  83  * "the daemon restarted from console" belong to the same domain. Thus, TOMOYO
  84  * provides a way to shorten domainnames.
  85  *
  86  * An entry is added by
  87  *
  88  * # echo 'initialize_domain /usr/sbin/httpd' > \
  89  *                               /sys/kernel/security/tomoyo/exception_policy
  90  *
  91  * and is deleted by
  92  *
  93  * # echo 'delete initialize_domain /usr/sbin/httpd' > \
  94  *                               /sys/kernel/security/tomoyo/exception_policy
  95  *
  96  * and all entries are retrieved by
  97  *
  98  * # grep ^initialize_domain /sys/kernel/security/tomoyo/exception_policy
  99  *
 100  * In the example above, /usr/sbin/httpd will belong to
 101  * "<kernel> /usr/sbin/httpd" domain.
 102  *
 103  * You may specify a domainname using "from" keyword.
 104  * "initialize_domain /usr/sbin/httpd from <kernel> /etc/rc.d/init.d/httpd"
 105  * will cause "/usr/sbin/httpd" executed from "<kernel> /etc/rc.d/init.d/httpd"
 106  * domain to belong to "<kernel> /usr/sbin/httpd" domain.
 107  *
 108  * You may add "no_" prefix to "initialize_domain".
 109  * "initialize_domain /usr/sbin/httpd" and
 110  * "no_initialize_domain /usr/sbin/httpd from <kernel> /etc/rc.d/init.d/httpd"
 111  * will cause "/usr/sbin/httpd" to belong to "<kernel> /usr/sbin/httpd" domain
 112  * unless executed from "<kernel> /etc/rc.d/init.d/httpd" domain.
 113  */
 114 LIST_HEAD(tomoyo_domain_initializer_list);
 115
 116 /**
 117  * tomoyo_update_domain_initializer_entry - Update "struct tomoyo_domain_initializer_entry" list.
 118  *
 119  * @domainname: The name of domain. May be NULL.
 120  * @program:    The name of program.
 121  * @is_not:     True if it is "no_initialize_domain" entry.
 122  * @is_delete:  True if it is a delete request.
 123  *
 124  * Returns 0 on success, negative value otherwise.
 125  *
 126  * Caller holds tomoyo_read_lock().
 127  */
 128 static int tomoyo_update_domain_initializer_entry(const char *domainname,
 129                                                   const char *program,
 130                                                   const bool is_not,
 131                                                   const bool is_delete)
 132 {
 133         struct tomoyo_domain_initializer_entry *ptr;
 134         struct tomoyo_domain_initializer_entry e = { .is_not = is_not };
 135         int error = is_delete ? -ENOENT : -ENOMEM;
 136
 137         if (!tomoyo_is_correct_path(program, 1, -1, -1))
 138                 return -EINVAL; /* No patterns allowed. */
 139         if (domainname) {
 140                 if (!tomoyo_is_domain_def(domainname) &&
 141                     tomoyo_is_correct_path(domainname, 1, -1, -1))
 142                         e.is_last_name = true;
 143                 else if (!tomoyo_is_correct_domain(domainname))
 144                         return -EINVAL;
 145                 e.domainname = tomoyo_get_name(domainname);
 146                 if (!e.domainname)
 147                         goto out;
 148         }
 149         e.program = tomoyo_get_name(program);
 150         if (!e.program)
 151                 goto out;
 152         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 153                 goto out;
 154         list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
 155                 if (!tomoyo_is_same_domain_initializer_entry(ptr, &e))
 156                         continue;
 157                 ptr->is_deleted = is_delete;
 158                 error = 0;
 159                 break;
 160         }
 161         if (!is_delete && error) {
 162                 struct tomoyo_domain_initializer_entry *entry =
 163                         tomoyo_commit_ok(&e, sizeof(e));
 164                 if (entry) {
 165                         list_add_tail_rcu(&entry->list,
 166                                           &tomoyo_domain_initializer_list);
 167                         error = 0;
 168                 }
 169         }
 170         mutex_unlock(&tomoyo_policy_lock);
 171  out:
 172         tomoyo_put_name(e.domainname);
 173         tomoyo_put_name(e.program);
 174         return error;
 175 }
 176
 177 /**
 178  * tomoyo_read_domain_initializer_policy - Read "struct tomoyo_domain_initializer_entry" list.
 179  *
 180  * @head: Pointer to "struct tomoyo_io_buffer".
 181  *
 182  * Returns true on success, false otherwise.
 183  *
 184  * Caller holds tomoyo_read_lock().
 185  */
 186 bool tomoyo_read_domain_initializer_policy(struct tomoyo_io_buffer *head)
 187 {
 188         struct list_head *pos;
 189         bool done = true;
 190
 191         list_for_each_cookie(pos, head->read_var2,
 192                              &tomoyo_domain_initializer_list) {
 193                 const char *no;
 194                 const char *from = "";
 195                 const char *domain = "";
 196                 struct tomoyo_domain_initializer_entry *ptr;
 197                 ptr = list_entry(pos, struct tomoyo_domain_initializer_entry,
 198                                   list);
 199                 if (ptr->is_deleted)
 200                         continue;
 201                 no = ptr->is_not ? "no_" : "";
 202                 if (ptr->domainname) {
 203                         from = " from ";
 204                         domain = ptr->domainname->name;
 205                 }
 206                 done = tomoyo_io_printf(head,
 207                                         "%s" TOMOYO_KEYWORD_INITIALIZE_DOMAIN
 208                                         "%s%s%s\n", no, ptr->program->name,
 209                                         from, domain);
 210                 if (!done)
 211                         break;
 212         }
 213         return done;
 214 }
 215
 216 /**
 217  * tomoyo_write_domain_initializer_policy - Write "struct tomoyo_domain_initializer_entry" list.
 218  *
 219  * @data:      String to parse.
 220  * @is_not:    True if it is "no_initialize_domain" entry.
 221  * @is_delete: True if it is a delete request.
 222  *
 223  * Returns 0 on success, negative value otherwise.
 224  *
 225  * Caller holds tomoyo_read_lock().
 226  */
 227 int tomoyo_write_domain_initializer_policy(char *data, const bool is_not,
 228                                            const bool is_delete)
 229 {
 230         char *cp = strstr(data, " from ");
 231
 232         if (cp) {
 233                 *cp = '\0';
 234                 return tomoyo_update_domain_initializer_entry(cp + 6, data,
 235                                                               is_not,
 236                                                               is_delete);
 237         }
 238         return tomoyo_update_domain_initializer_entry(NULL, data, is_not,
 239                                                       is_delete);
 240 }
 241
 242 /**
 243  * tomoyo_is_domain_initializer - Check whether the given program causes domainname reinitialization.
 244  *
 245  * @domainname: The name of domain.
 246  * @program:    The name of program.
 247  * @last_name:  The last component of @domainname.
 248  *
 249  * Returns true if executing @program reinitializes domain transition,
 250  * false otherwise.
 251  *
 252  * Caller holds tomoyo_read_lock().
 253  */
 254 static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
 255                                          domainname,
 256                                          const struct tomoyo_path_info *program,
 257                                          const struct tomoyo_path_info *
 258                                          last_name)
 259 {
 260         struct tomoyo_domain_initializer_entry *ptr;
 261         bool flag = false;
 262
 263         list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
 264                 if (ptr->is_deleted)
 265                         continue;
 266                 if (ptr->domainname) {
 267                         if (!ptr->is_last_name) {
 268                                 if (ptr->domainname != domainname)
 269                                         continue;
 270                         } else {
 271                                 if (tomoyo_pathcmp(ptr->domainname, last_name))
 272                                         continue;
 273                         }
 274                 }
 275                 if (tomoyo_pathcmp(ptr->program, program))
 276                         continue;
 277                 if (ptr->is_not) {
 278                         flag = false;
 279                         break;
 280                 }
 281                 flag = true;
 282         }
 283         return flag;
 284 }
 285
 286 /*
 287  * tomoyo_domain_keeper_list is used for holding list of domainnames which
 288  * suppresses domain transition. Normally, a domainname is monotonically
 289  * getting longer. But sometimes, we want to suppress domain transition.
 290  * It would be convenient for us that programs executed from a login session
 291  * belong to the same domain. Thus, TOMOYO provides a way to suppress domain
 292  * transition.
 293  *
 294  * An entry is added by
 295  *
 296  * # echo 'keep_domain <kernel> /usr/sbin/sshd /bin/bash' > \
 297  *                              /sys/kernel/security/tomoyo/exception_policy
 298  *
 299  * and is deleted by
 300  *
 301  * # echo 'delete keep_domain <kernel> /usr/sbin/sshd /bin/bash' > \
 302  *                              /sys/kernel/security/tomoyo/exception_policy
 303  *
 304  * and all entries are retrieved by
 305  *
 306  * # grep ^keep_domain /sys/kernel/security/tomoyo/exception_policy
 307  *
 308  * In the example above, any process which belongs to
 309  * "<kernel> /usr/sbin/sshd /bin/bash" domain will remain in that domain,
 310  * unless explicitly specified by "initialize_domain" or "no_keep_domain".
 311  *
 312  * You may specify a program using "from" keyword.
 313  * "keep_domain /bin/pwd from <kernel> /usr/sbin/sshd /bin/bash"
 314  * will cause "/bin/pwd" executed from "<kernel> /usr/sbin/sshd /bin/bash"
 315  * domain to remain in "<kernel> /usr/sbin/sshd /bin/bash" domain.
 316  *
 317  * You may add "no_" prefix to "keep_domain".
 318  * "keep_domain <kernel> /usr/sbin/sshd /bin/bash" and
 319  * "no_keep_domain /usr/bin/passwd from <kernel> /usr/sbin/sshd /bin/bash" will
 320  * cause "/usr/bin/passwd" to belong to
 321  * "<kernel> /usr/sbin/sshd /bin/bash /usr/bin/passwd" domain, unless
 322  * explicitly specified by "initialize_domain".
 323  */
 324 LIST_HEAD(tomoyo_domain_keeper_list);
 325
 326 /**
 327  * tomoyo_update_domain_keeper_entry - Update "struct tomoyo_domain_keeper_entry" list.
 328  *
 329  * @domainname: The name of domain.
 330  * @program:    The name of program. May be NULL.
 331  * @is_not:     True if it is "no_keep_domain" entry.
 332  * @is_delete:  True if it is a delete request.
 333  *
 334  * Returns 0 on success, negative value otherwise.
 335  *
 336  * Caller holds tomoyo_read_lock().
 337  */
 338 static int tomoyo_update_domain_keeper_entry(const char *domainname,
 339                                              const char *program,
 340                                              const bool is_not,
 341                                              const bool is_delete)
 342 {
 343         struct tomoyo_domain_keeper_entry *ptr;
 344         struct tomoyo_domain_keeper_entry e = { .is_not = is_not };
 345         int error = is_delete ? -ENOENT : -ENOMEM;
 346
 347         if (!tomoyo_is_domain_def(domainname) &&
 348             tomoyo_is_correct_path(domainname, 1, -1, -1))
 349                 e.is_last_name = true;
 350         else if (!tomoyo_is_correct_domain(domainname))
 351                 return -EINVAL;
 352         if (program) {
 353                 if (!tomoyo_is_correct_path(program, 1, -1, -1))
 354                         return -EINVAL;
 355                 e.program = tomoyo_get_name(program);
 356                 if (!e.program)
 357                         goto out;
 358         }
 359         e.domainname = tomoyo_get_name(domainname);
 360         if (!e.domainname)
 361                 goto out;
 362         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 363                 goto out;
 364         list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
 365                 if (!tomoyo_is_same_domain_keeper_entry(ptr, &e))
 366                         continue;
 367                 ptr->is_deleted = is_delete;
 368                 error = 0;
 369                 break;
 370         }
 371         if (!is_delete && error) {
 372                 struct tomoyo_domain_keeper_entry *entry =
 373                         tomoyo_commit_ok(&e, sizeof(e));
 374                 if (entry) {
 375                         list_add_tail_rcu(&entry->list,
 376                                           &tomoyo_domain_keeper_list);
 377                         error = 0;
 378                 }
 379         }
 380         mutex_unlock(&tomoyo_policy_lock);
 381  out:
 382         tomoyo_put_name(e.domainname);
 383         tomoyo_put_name(e.program);
 384         return error;
 385 }
 386
 387 /**
 388  * tomoyo_write_domain_keeper_policy - Write "struct tomoyo_domain_keeper_entry" list.
 389  *
 390  * @data:      String to parse.
 391  * @is_not:    True if it is "no_keep_domain" entry.
 392  * @is_delete: True if it is a delete request.
 393  *
 394  * Caller holds tomoyo_read_lock().
 395  */
 396 int tomoyo_write_domain_keeper_policy(char *data, const bool is_not,
 397                                       const bool is_delete)
 398 {
 399         char *cp = strstr(data, " from ");
 400
 401         if (cp) {
 402                 *cp = '\0';
 403                 return tomoyo_update_domain_keeper_entry(cp + 6, data, is_not,
 404                                                          is_delete);
 405         }
 406         return tomoyo_update_domain_keeper_entry(data, NULL, is_not, is_delete);
 407 }
 408
 409 /**
 410  * tomoyo_read_domain_keeper_policy - Read "struct tomoyo_domain_keeper_entry" list.
 411  *
 412  * @head: Pointer to "struct tomoyo_io_buffer".
 413  *
 414  * Returns true on success, false otherwise.
 415  *
 416  * Caller holds tomoyo_read_lock().
 417  */
 418 bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
 419 {
 420         struct list_head *pos;
 421         bool done = true;
 422
 423         list_for_each_cookie(pos, head->read_var2,
 424                              &tomoyo_domain_keeper_list) {
 425                 struct tomoyo_domain_keeper_entry *ptr;
 426                 const char *no;
 427                 const char *from = "";
 428                 const char *program = "";
 429
 430                 ptr = list_entry(pos, struct tomoyo_domain_keeper_entry, list);
 431                 if (ptr->is_deleted)
 432                         continue;
 433                 no = ptr->is_not ? "no_" : "";
 434                 if (ptr->program) {
 435                         from = " from ";
 436                         program = ptr->program->name;
 437                 }
 438                 done = tomoyo_io_printf(head,
 439                                         "%s" TOMOYO_KEYWORD_KEEP_DOMAIN
 440                                         "%s%s%s\n", no, program, from,
 441                                         ptr->domainname->name);
 442                 if (!done)
 443                         break;
 444         }
 445         return done;
 446 }
 447
 448 /**
 449  * tomoyo_is_domain_keeper - Check whether the given program causes domain transition suppression.
 450  *
 451  * @domainname: The name of domain.
 452  * @program:    The name of program.
 453  * @last_name:  The last component of @domainname.
 454  *
 455  * Returns true if executing @program supresses domain transition,
 456  * false otherwise.
 457  *
 458  * Caller holds tomoyo_read_lock().
 459  */
 460 static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
 461                                     const struct tomoyo_path_info *program,
 462                                     const struct tomoyo_path_info *last_name)
 463 {
 464         struct tomoyo_domain_keeper_entry *ptr;
 465         bool flag = false;
 466
 467         list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
 468                 if (ptr->is_deleted)
 469                         continue;
 470                 if (!ptr->is_last_name) {
 471                         if (ptr->domainname != domainname)
 472                                 continue;
 473                 } else {
 474                         if (tomoyo_pathcmp(ptr->domainname, last_name))
 475                                 continue;
 476                 }
 477                 if (ptr->program && tomoyo_pathcmp(ptr->program, program))
 478                         continue;
 479                 if (ptr->is_not) {
 480                         flag = false;
 481                         break;
 482                 }
 483                 flag = true;
 484         }
 485         return flag;
 486 }
 487
 488 /*
 489  * tomoyo_alias_list is used for holding list of symlink's pathnames which are
 490  * allowed to be passed to an execve() request. Normally, the domainname which
 491  * the current process will belong to after execve() succeeds is calculated
 492  * using dereferenced pathnames. But some programs behave differently depending
 493  * on the name passed to argv[0]. For busybox, calculating domainname using
 494  * dereferenced pathnames will cause all programs in the busybox to belong to
 495  * the same domain. Thus, TOMOYO provides a way to allow use of symlink's
 496  * pathname for checking execve()'s permission and calculating domainname which
 497  * the current process will belong to after execve() succeeds.
 498  *
 499  * An entry is added by
 500  *
 501  * # echo 'alias /bin/busybox /bin/cat' > \
 502  *                            /sys/kernel/security/tomoyo/exception_policy
 503  *
 504  * and is deleted by
 505  *
 506  * # echo 'delete alias /bin/busybox /bin/cat' > \
 507  *                            /sys/kernel/security/tomoyo/exception_policy
 508  *
 509  * and all entries are retrieved by
 510  *
 511  * # grep ^alias /sys/kernel/security/tomoyo/exception_policy
 512  *
 513  * In the example above, if /bin/cat is a symlink to /bin/busybox and execution
 514  * of /bin/cat is requested, permission is checked for /bin/cat rather than
 515  * /bin/busybox and domainname which the current process will belong to after
 516  * execve() succeeds is calculated using /bin/cat rather than /bin/busybox .
 517  */
 518 LIST_HEAD(tomoyo_alias_list);
 519
 520 /**
 521  * tomoyo_update_alias_entry - Update "struct tomoyo_alias_entry" list.
 522  *
 523  * @original_name: The original program's real name.
 524  * @aliased_name:  The symbolic program's symbolic link's name.
 525  * @is_delete:     True if it is a delete request.
 526  *
 527  * Returns 0 on success, negative value otherwise.
 528  *
 529  * Caller holds tomoyo_read_lock().
 530  */
 531 static int tomoyo_update_alias_entry(const char *original_name,
 532                                      const char *aliased_name,
 533                                      const bool is_delete)
 534 {
 535         struct tomoyo_alias_entry *ptr;
 536         struct tomoyo_alias_entry e = { };
 537         int error = is_delete ? -ENOENT : -ENOMEM;
 538
 539         if (!tomoyo_is_correct_path(original_name, 1, -1, -1) ||
 540             !tomoyo_is_correct_path(aliased_name, 1, -1, -1))
 541                 return -EINVAL; /* No patterns allowed. */
 542         e.original_name = tomoyo_get_name(original_name);
 543         e.aliased_name = tomoyo_get_name(aliased_name);
 544         if (!e.original_name || !e.aliased_name)
 545                 goto out;
 546         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 547                 goto out;
 548         list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 549                 if (!tomoyo_is_same_alias_entry(ptr, &e))
 550                         continue;
 551                 ptr->is_deleted = is_delete;
 552                 error = 0;
 553                 break;
 554         }
 555         if (!is_delete && error) {
 556                 struct tomoyo_alias_entry *entry =
 557                         tomoyo_commit_ok(&e, sizeof(e));
 558                 if (entry) {
 559                         list_add_tail_rcu(&entry->list, &tomoyo_alias_list);
 560                         error = 0;
 561                 }
 562         }
 563         mutex_unlock(&tomoyo_policy_lock);
 564  out:
 565         tomoyo_put_name(e.original_name);
 566         tomoyo_put_name(e.aliased_name);
 567         return error;
 568 }
 569
 570 /**
 571  * tomoyo_read_alias_policy - Read "struct tomoyo_alias_entry" list.
 572  *
 573  * @head: Pointer to "struct tomoyo_io_buffer".
 574  *
 575  * Returns true on success, false otherwise.
 576  *
 577  * Caller holds tomoyo_read_lock().
 578  */
 579 bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
 580 {
 581         struct list_head *pos;
 582         bool done = true;
 583
 584         list_for_each_cookie(pos, head->read_var2, &tomoyo_alias_list) {
 585                 struct tomoyo_alias_entry *ptr;
 586
 587                 ptr = list_entry(pos, struct tomoyo_alias_entry, list);
 588                 if (ptr->is_deleted)
 589                         continue;
 590                 done = tomoyo_io_printf(head, TOMOYO_KEYWORD_ALIAS "%s %s\n",
 591                                         ptr->original_name->name,
 592                                         ptr->aliased_name->name);
 593                 if (!done)
 594                         break;
 595         }
 596         return done;
 597 }
 598
 599 /**
 600  * tomoyo_write_alias_policy - Write "struct tomoyo_alias_entry" list.
 601  *
 602  * @data:      String to parse.
 603  * @is_delete: True if it is a delete request.
 604  *
 605  * Returns 0 on success, negative value otherwise.
 606  *
 607  * Caller holds tomoyo_read_lock().
 608  */
 609 int tomoyo_write_alias_policy(char *data, const bool is_delete)
 610 {
 611         char *cp = strchr(data, ' ');
 612
 613         if (!cp)
 614                 return -EINVAL;
 615         *cp++ = '\0';
 616         return tomoyo_update_alias_entry(data, cp, is_delete);
 617 }
 618
 619 /**
 620  * tomoyo_find_or_assign_new_domain - Create a domain.
 621  *
 622  * @domainname: The name of domain.
 623  * @profile:    Profile number to assign if the domain was newly created.
 624  *
 625  * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
 626  *
 627  * Caller holds tomoyo_read_lock().
 628  */
 629 struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 630                                                             domainname,
 631                                                             const u8 profile)
 632 {
 633         struct tomoyo_domain_info *entry;
 634         struct tomoyo_domain_info *domain = NULL;
 635         const struct tomoyo_path_info *saved_domainname;
 636         bool found = false;
 637
 638         if (!tomoyo_is_correct_domain(domainname))
 639                 return NULL;
 640         saved_domainname = tomoyo_get_name(domainname);
 641         if (!saved_domainname)
 642                 return NULL;
 643         entry = kzalloc(sizeof(*entry), GFP_NOFS);
 644         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 645                 goto out;
 646         list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
 647                 if (domain->is_deleted ||
 648                     tomoyo_pathcmp(saved_domainname, domain->domainname))
 649                         continue;
 650                 found = true;
 651                 break;
 652         }
 653         if (!found && tomoyo_memory_ok(entry)) {
 654                 INIT_LIST_HEAD(&entry->acl_info_list);
 655                 entry->domainname = saved_domainname;
 656                 saved_domainname = NULL;
 657                 entry->profile = profile;
 658                 list_add_tail_rcu(&entry->list, &tomoyo_domain_list);
 659                 domain = entry;
 660                 entry = NULL;
 661                 found = true;
 662         }
 663         mutex_unlock(&tomoyo_policy_lock);
 664  out:
 665         tomoyo_put_name(saved_domainname);
 666         kfree(entry);
 667         return found ? domain : NULL;
 668 }
 669
 670 /**
 671  * tomoyo_find_next_domain - Find a domain.
 672  *
 673  * @bprm: Pointer to "struct linux_binprm".
 674  *
 675  * Returns 0 on success, negative value otherwise.
 676  *
 677  * Caller holds tomoyo_read_lock().
 678  */
 679 int tomoyo_find_next_domain(struct linux_binprm *bprm)
 680 {
 681         /*
 682          * This function assumes that the size of buffer returned by
 683          * tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
 684          */
 685         struct tomoyo_page_buffer *tmp = kzalloc(sizeof(*tmp), GFP_NOFS);
 686         struct tomoyo_domain_info *old_domain = tomoyo_domain();
 687         struct tomoyo_domain_info *domain = NULL;
 688         const char *old_domain_name = old_domain->domainname->name;
 689         const char *original_name = bprm->filename;
 690         char *new_domain_name = NULL;
 691         char *real_program_name = NULL;
 692         char *symlink_program_name = NULL;
 693         const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
 694         const bool is_enforce = (mode == 3);
 695         int retval = -ENOMEM;
 696         struct tomoyo_path_info r; /* real name */
 697         struct tomoyo_path_info s; /* symlink name */
 698         struct tomoyo_path_info l; /* last name */
 699         static bool initialized;
 700
 701         if (!tmp)
 702                 goto out;
 703
 704         if (!initialized) {
 705                 /*
 706                  * Built-in initializers. This is needed because policies are
 707                  * not loaded until starting /sbin/init.
 708                  */
 709                 tomoyo_update_domain_initializer_entry(NULL, "/sbin/hotplug",
 710                                                        false, false);
 711                 tomoyo_update_domain_initializer_entry(NULL, "/sbin/modprobe",
 712                                                        false, false);
 713                 initialized = true;
 714         }
 715
 716         /* Get tomoyo_realpath of program. */
 717         retval = -ENOENT;
 718         /* I hope tomoyo_realpath() won't fail with -ENOMEM. */
 719         real_program_name = tomoyo_realpath(original_name);
 720         if (!real_program_name)
 721                 goto out;
 722         /* Get tomoyo_realpath of symbolic link. */
 723         symlink_program_name = tomoyo_realpath_nofollow(original_name);
 724         if (!symlink_program_name)
 725                 goto out;
 726
 727         r.name = real_program_name;
 728         tomoyo_fill_path_info(&r);
 729         s.name = symlink_program_name;
 730         tomoyo_fill_path_info(&s);
 731         l.name = tomoyo_get_last_name(old_domain);
 732         tomoyo_fill_path_info(&l);
 733
 734         /* Check 'alias' directive. */
 735         if (tomoyo_pathcmp(&r, &s)) {
 736                 struct tomoyo_alias_entry *ptr;
 737                 /* Is this program allowed to be called via symbolic links? */
 738                 list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 739                         if (ptr->is_deleted ||
 740                             tomoyo_pathcmp(&r, ptr->original_name) ||
 741                             tomoyo_pathcmp(&s, ptr->aliased_name))
 742                                 continue;
 743                         memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
 744                         strncpy(real_program_name, ptr->aliased_name->name,
 745                                 TOMOYO_MAX_PATHNAME_LEN - 1);
 746                         tomoyo_fill_path_info(&r);
 747                         break;
 748                 }
 749         }
 750
 751         /* Check execute permission. */
 752         retval = tomoyo_check_exec_perm(old_domain, &r);
 753         if (retval < 0)
 754                 goto out;
 755
 756         new_domain_name = tmp->buffer;
 757         if (tomoyo_is_domain_initializer(old_domain->domainname, &r, &l)) {
 758                 /* Transit to the child of tomoyo_kernel_domain domain. */
 759                 snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
 760                          TOMOYO_ROOT_NAME " " "%s", real_program_name);
 761         } else if (old_domain == &tomoyo_kernel_domain &&
 762                    !tomoyo_policy_loaded) {
 763                 /*
 764                  * Needn't to transit from kernel domain before starting
 765                  * /sbin/init. But transit from kernel domain if executing
 766                  * initializers because they might start before /sbin/init.
 767                  */
 768                 domain = old_domain;
 769         } else if (tomoyo_is_domain_keeper(old_domain->domainname, &r, &l)) {
 770                 /* Keep current domain. */
 771                 domain = old_domain;
 772         } else {
 773                 /* Normal domain transition. */
 774                 snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
 775                          "%s %s", old_domain_name, real_program_name);
 776         }
 777         if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
 778                 goto done;
 779         domain = tomoyo_find_domain(new_domain_name);
 780         if (domain)
 781                 goto done;
 782         if (is_enforce)
 783                 goto done;
 784         domain = tomoyo_find_or_assign_new_domain(new_domain_name,
 785                                                   old_domain->profile);
 786  done:
 787         if (domain)
 788                 goto out;
 789         printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
 790                new_domain_name);
 791         if (is_enforce)
 792                 retval = -EPERM;
 793         else
 794                 old_domain->transition_failed = true;
 795  out:
 796         if (!domain)
 797                 domain = old_domain;
 798         /* Update reference count on "struct tomoyo_domain_info". */
 799         atomic_inc(&domain->users);
 800         bprm->cred->security = domain;
 801         kfree(real_program_name);
 802         kfree(symlink_program_name);
 803         kfree(tmp);
 804         return retval;
 805 }