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 "tomoyo.h"
  14 #include "realpath.h"
  15 #include <linux/binfmts.h>
  16
  17 /* Variables definitions.*/
  18
  19 /* The initial domain. */
  20 struct tomoyo_domain_info tomoyo_kernel_domain;
  21
  22 /*
  23  * tomoyo_domain_list is used for holding list of domains.
  24  * The ->acl_info_list of "struct tomoyo_domain_info" is used for holding
  25  * permissions (e.g. "allow_read /lib/libc-2.5.so") given to each domain.
  26  *
  27  * An entry is added by
  28  *
  29  * # ( echo "<kernel>"; echo "allow_execute /sbin/init" ) > \
  30  *                                  /sys/kernel/security/tomoyo/domain_policy
  31  *
  32  * and is deleted by
  33  *
  34  * # ( echo "<kernel>"; echo "delete allow_execute /sbin/init" ) > \
  35  *                                  /sys/kernel/security/tomoyo/domain_policy
  36  *
  37  * and all entries are retrieved by
  38  *
  39  * # cat /sys/kernel/security/tomoyo/domain_policy
  40  *
  41  * A domain is added by
  42  *
  43  * # echo "<kernel>" > /sys/kernel/security/tomoyo/domain_policy
  44  *
  45  * and is deleted by
  46  *
  47  * # echo "delete <kernel>" > /sys/kernel/security/tomoyo/domain_policy
  48  *
  49  * and all domains are retrieved by
  50  *
  51  * # grep '^<kernel>' /sys/kernel/security/tomoyo/domain_policy
  52  *
  53  * Normally, a domainname is monotonically getting longer because a domainname
  54  * which the process will belong to if an execve() operation succeeds is
  55  * defined as a concatenation of "current domainname" + "pathname passed to
  56  * execve()".
  57  * See tomoyo_domain_initializer_list and tomoyo_domain_keeper_list for
  58  * exceptions.
  59  */
  60 LIST_HEAD(tomoyo_domain_list);
  61 DECLARE_RWSEM(tomoyo_domain_list_lock);
  62
  63 /*
  64  * tomoyo_domain_initializer_entry is a structure which is used for holding
  65  * "initialize_domain" and "no_initialize_domain" entries.
  66  * It has following fields.
  67  *
  68  *  (1) "list" which is linked to tomoyo_domain_initializer_list .
  69  *  (2) "domainname" which is "a domainname" or "the last component of a
  70  *      domainname". This field is NULL if "from" clause is not specified.
  71  *  (3) "program" which is a program's pathname.
  72  *  (4) "is_deleted" is a bool which is true if marked as deleted, false
  73  *      otherwise.
  74  *  (5) "is_not" is a bool which is true if "no_initialize_domain", false
  75  *      otherwise.
  76  *  (6) "is_last_name" is a bool which is true if "domainname" is "the last
  77  *      component of a domainname", false otherwise.
  78  */
  79 struct tomoyo_domain_initializer_entry {
  80         struct list_head list;
  81         const struct tomoyo_path_info *domainname;    /* This may be NULL */
  82         const struct tomoyo_path_info *program;
  83         bool is_deleted;
  84         bool is_not;       /* True if this entry is "no_initialize_domain".  */
  85         /* True if the domainname is tomoyo_get_last_name(). */
  86         bool is_last_name;
  87 };
  88
  89 /*
  90  * tomoyo_domain_keeper_entry is a structure which is used for holding
  91  * "keep_domain" and "no_keep_domain" entries.
  92  * It has following fields.
  93  *
  94  *  (1) "list" which is linked to tomoyo_domain_keeper_list .
  95  *  (2) "domainname" which is "a domainname" or "the last component of a
  96  *      domainname".
  97  *  (3) "program" which is a program's pathname.
  98  *      This field is NULL if "from" clause is not specified.
  99  *  (4) "is_deleted" is a bool which is true if marked as deleted, false
 100  *      otherwise.
 101  *  (5) "is_not" is a bool which is true if "no_initialize_domain", false
 102  *      otherwise.
 103  *  (6) "is_last_name" is a bool which is true if "domainname" is "the last
 104  *      component of a domainname", false otherwise.
 105  */
 106 struct tomoyo_domain_keeper_entry {
 107         struct list_head list;
 108         const struct tomoyo_path_info *domainname;
 109         const struct tomoyo_path_info *program;       /* This may be NULL */
 110         bool is_deleted;
 111         bool is_not;       /* True if this entry is "no_keep_domain".        */
 112         /* True if the domainname is tomoyo_get_last_name(). */
 113         bool is_last_name;
 114 };
 115
 116 /*
 117  * tomoyo_alias_entry is a structure which is used for holding "alias" entries.
 118  * It has following fields.
 119  *
 120  *  (1) "list" which is linked to tomoyo_alias_list .
 121  *  (2) "original_name" which is a dereferenced pathname.
 122  *  (3) "aliased_name" which is a symlink's pathname.
 123  *  (4) "is_deleted" is a bool which is true if marked as deleted, false
 124  *      otherwise.
 125  */
 126 struct tomoyo_alias_entry {
 127         struct list_head list;
 128         const struct tomoyo_path_info *original_name;
 129         const struct tomoyo_path_info *aliased_name;
 130         bool is_deleted;
 131 };
 132
 133 /**
 134  * tomoyo_set_domain_flag - Set or clear domain's attribute flags.
 135  *
 136  * @domain:    Pointer to "struct tomoyo_domain_info".
 137  * @is_delete: True if it is a delete request.
 138  * @flags:     Flags to set or clear.
 139  *
 140  * Returns nothing.
 141  */
 142 void tomoyo_set_domain_flag(struct tomoyo_domain_info *domain,
 143                             const bool is_delete, const u8 flags)
 144 {
 145         /* We need to serialize because this is bitfield operation. */
 146         static DEFINE_SPINLOCK(lock);
 147         spin_lock(&lock);
 148         if (!is_delete)
 149                 domain->flags |= flags;
 150         else
 151                 domain->flags &= ~flags;
 152         spin_unlock(&lock);
 153 }
 154
 155 /**
 156  * tomoyo_get_last_name - Get last component of a domainname.
 157  *
 158  * @domain: Pointer to "struct tomoyo_domain_info".
 159  *
 160  * Returns the last component of the domainname.
 161  */
 162 const char *tomoyo_get_last_name(const struct tomoyo_domain_info *domain)
 163 {
 164         const char *cp0 = domain->domainname->name;
 165         const char *cp1 = strrchr(cp0, ' ');
 166
 167         if (cp1)
 168                 return cp1 + 1;
 169         return cp0;
 170 }
 171
 172 /*
 173  * tomoyo_domain_initializer_list is used for holding list of programs which
 174  * triggers reinitialization of domainname. Normally, a domainname is
 175  * monotonically getting longer. But sometimes, we restart daemon programs.
 176  * It would be convenient for us that "a daemon started upon system boot" and
 177  * "the daemon restarted from console" belong to the same domain. Thus, TOMOYO
 178  * provides a way to shorten domainnames.
 179  *
 180  * An entry is added by
 181  *
 182  * # echo 'initialize_domain /usr/sbin/httpd' > \
 183  *                               /sys/kernel/security/tomoyo/exception_policy
 184  *
 185  * and is deleted by
 186  *
 187  * # echo 'delete initialize_domain /usr/sbin/httpd' > \
 188  *                               /sys/kernel/security/tomoyo/exception_policy
 189  *
 190  * and all entries are retrieved by
 191  *
 192  * # grep ^initialize_domain /sys/kernel/security/tomoyo/exception_policy
 193  *
 194  * In the example above, /usr/sbin/httpd will belong to
 195  * "<kernel> /usr/sbin/httpd" domain.
 196  *
 197  * You may specify a domainname using "from" keyword.
 198  * "initialize_domain /usr/sbin/httpd from <kernel> /etc/rc.d/init.d/httpd"
 199  * will cause "/usr/sbin/httpd" executed from "<kernel> /etc/rc.d/init.d/httpd"
 200  * domain to belong to "<kernel> /usr/sbin/httpd" domain.
 201  *
 202  * You may add "no_" prefix to "initialize_domain".
 203  * "initialize_domain /usr/sbin/httpd" and
 204  * "no_initialize_domain /usr/sbin/httpd from <kernel> /etc/rc.d/init.d/httpd"
 205  * will cause "/usr/sbin/httpd" to belong to "<kernel> /usr/sbin/httpd" domain
 206  * unless executed from "<kernel> /etc/rc.d/init.d/httpd" domain.
 207  */
 208 static LIST_HEAD(tomoyo_domain_initializer_list);
 209 static DECLARE_RWSEM(tomoyo_domain_initializer_list_lock);
 210
 211 /**
 212  * tomoyo_update_domain_initializer_entry - Update "struct tomoyo_domain_initializer_entry" list.
 213  *
 214  * @domainname: The name of domain. May be NULL.
 215  * @program:    The name of program.
 216  * @is_not:     True if it is "no_initialize_domain" entry.
 217  * @is_delete:  True if it is a delete request.
 218  *
 219  * Returns 0 on success, negative value otherwise.
 220  *
 221  * Caller holds tomoyo_read_lock().
 222  */
 223 static int tomoyo_update_domain_initializer_entry(const char *domainname,
 224                                                   const char *program,
 225                                                   const bool is_not,
 226                                                   const bool is_delete)
 227 {
 228         struct tomoyo_domain_initializer_entry *new_entry;
 229         struct tomoyo_domain_initializer_entry *ptr;
 230         const struct tomoyo_path_info *saved_program;
 231         const struct tomoyo_path_info *saved_domainname = NULL;
 232         int error = -ENOMEM;
 233         bool is_last_name = false;
 234
 235         if (!tomoyo_is_correct_path(program, 1, -1, -1, __func__))
 236                 return -EINVAL; /* No patterns allowed. */
 237         if (domainname) {
 238                 if (!tomoyo_is_domain_def(domainname) &&
 239                     tomoyo_is_correct_path(domainname, 1, -1, -1, __func__))
 240                         is_last_name = true;
 241                 else if (!tomoyo_is_correct_domain(domainname, __func__))
 242                         return -EINVAL;
 243                 saved_domainname = tomoyo_save_name(domainname);
 244                 if (!saved_domainname)
 245                         return -ENOMEM;
 246         }
 247         saved_program = tomoyo_save_name(program);
 248         if (!saved_program)
 249                 return -ENOMEM;
 250         down_write(&tomoyo_domain_initializer_list_lock);
 251         list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
 252                 if (ptr->is_not != is_not ||
 253                     ptr->domainname != saved_domainname ||
 254                     ptr->program != saved_program)
 255                         continue;
 256                 ptr->is_deleted = is_delete;
 257                 error = 0;
 258                 goto out;
 259         }
 260         if (is_delete) {
 261                 error = -ENOENT;
 262                 goto out;
 263         }
 264         new_entry = tomoyo_alloc_element(sizeof(*new_entry));
 265         if (!new_entry)
 266                 goto out;
 267         new_entry->domainname = saved_domainname;
 268         new_entry->program = saved_program;
 269         new_entry->is_not = is_not;
 270         new_entry->is_last_name = is_last_name;
 271         list_add_tail_rcu(&new_entry->list, &tomoyo_domain_initializer_list);
 272         error = 0;
 273  out:
 274         up_write(&tomoyo_domain_initializer_list_lock);
 275         return error;
 276 }
 277
 278 /**
 279  * tomoyo_read_domain_initializer_policy - Read "struct tomoyo_domain_initializer_entry" list.
 280  *
 281  * @head: Pointer to "struct tomoyo_io_buffer".
 282  *
 283  * Returns true on success, false otherwise.
 284  *
 285  * Caller holds tomoyo_read_lock().
 286  */
 287 bool tomoyo_read_domain_initializer_policy(struct tomoyo_io_buffer *head)
 288 {
 289         struct list_head *pos;
 290         bool done = true;
 291
 292         list_for_each_cookie(pos, head->read_var2,
 293                              &tomoyo_domain_initializer_list) {
 294                 const char *no;
 295                 const char *from = "";
 296                 const char *domain = "";
 297                 struct tomoyo_domain_initializer_entry *ptr;
 298                 ptr = list_entry(pos, struct tomoyo_domain_initializer_entry,
 299                                   list);
 300                 if (ptr->is_deleted)
 301                         continue;
 302                 no = ptr->is_not ? "no_" : "";
 303                 if (ptr->domainname) {
 304                         from = " from ";
 305                         domain = ptr->domainname->name;
 306                 }
 307                 done = tomoyo_io_printf(head,
 308                                         "%s" TOMOYO_KEYWORD_INITIALIZE_DOMAIN
 309                                         "%s%s%s\n", no, ptr->program->name,
 310                                         from, domain);
 311                 if (!done)
 312                         break;
 313         }
 314         return done;
 315 }
 316
 317 /**
 318  * tomoyo_write_domain_initializer_policy - Write "struct tomoyo_domain_initializer_entry" list.
 319  *
 320  * @data:      String to parse.
 321  * @is_not:    True if it is "no_initialize_domain" entry.
 322  * @is_delete: True if it is a delete request.
 323  *
 324  * Returns 0 on success, negative value otherwise.
 325  *
 326  * Caller holds tomoyo_read_lock().
 327  */
 328 int tomoyo_write_domain_initializer_policy(char *data, const bool is_not,
 329                                            const bool is_delete)
 330 {
 331         char *cp = strstr(data, " from ");
 332
 333         if (cp) {
 334                 *cp = '\0';
 335                 return tomoyo_update_domain_initializer_entry(cp + 6, data,
 336                                                               is_not,
 337                                                               is_delete);
 338         }
 339         return tomoyo_update_domain_initializer_entry(NULL, data, is_not,
 340                                                       is_delete);
 341 }
 342
 343 /**
 344  * tomoyo_is_domain_initializer - Check whether the given program causes domainname reinitialization.
 345  *
 346  * @domainname: The name of domain.
 347  * @program:    The name of program.
 348  * @last_name:  The last component of @domainname.
 349  *
 350  * Returns true if executing @program reinitializes domain transition,
 351  * false otherwise.
 352  *
 353  * Caller holds tomoyo_read_lock().
 354  */
 355 static bool tomoyo_is_domain_initializer(const struct tomoyo_path_info *
 356                                          domainname,
 357                                          const struct tomoyo_path_info *program,
 358                                          const struct tomoyo_path_info *
 359                                          last_name)
 360 {
 361         struct tomoyo_domain_initializer_entry *ptr;
 362         bool flag = false;
 363
 364         list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
 365                 if (ptr->is_deleted)
 366                         continue;
 367                 if (ptr->domainname) {
 368                         if (!ptr->is_last_name) {
 369                                 if (ptr->domainname != domainname)
 370                                         continue;
 371                         } else {
 372                                 if (tomoyo_pathcmp(ptr->domainname, last_name))
 373                                         continue;
 374                         }
 375                 }
 376                 if (tomoyo_pathcmp(ptr->program, program))
 377                         continue;
 378                 if (ptr->is_not) {
 379                         flag = false;
 380                         break;
 381                 }
 382                 flag = true;
 383         }
 384         return flag;
 385 }
 386
 387 /*
 388  * tomoyo_domain_keeper_list is used for holding list of domainnames which
 389  * suppresses domain transition. Normally, a domainname is monotonically
 390  * getting longer. But sometimes, we want to suppress domain transition.
 391  * It would be convenient for us that programs executed from a login session
 392  * belong to the same domain. Thus, TOMOYO provides a way to suppress domain
 393  * transition.
 394  *
 395  * An entry is added by
 396  *
 397  * # echo 'keep_domain <kernel> /usr/sbin/sshd /bin/bash' > \
 398  *                              /sys/kernel/security/tomoyo/exception_policy
 399  *
 400  * and is deleted by
 401  *
 402  * # echo 'delete keep_domain <kernel> /usr/sbin/sshd /bin/bash' > \
 403  *                              /sys/kernel/security/tomoyo/exception_policy
 404  *
 405  * and all entries are retrieved by
 406  *
 407  * # grep ^keep_domain /sys/kernel/security/tomoyo/exception_policy
 408  *
 409  * In the example above, any process which belongs to
 410  * "<kernel> /usr/sbin/sshd /bin/bash" domain will remain in that domain,
 411  * unless explicitly specified by "initialize_domain" or "no_keep_domain".
 412  *
 413  * You may specify a program using "from" keyword.
 414  * "keep_domain /bin/pwd from <kernel> /usr/sbin/sshd /bin/bash"
 415  * will cause "/bin/pwd" executed from "<kernel> /usr/sbin/sshd /bin/bash"
 416  * domain to remain in "<kernel> /usr/sbin/sshd /bin/bash" domain.
 417  *
 418  * You may add "no_" prefix to "keep_domain".
 419  * "keep_domain <kernel> /usr/sbin/sshd /bin/bash" and
 420  * "no_keep_domain /usr/bin/passwd from <kernel> /usr/sbin/sshd /bin/bash" will
 421  * cause "/usr/bin/passwd" to belong to
 422  * "<kernel> /usr/sbin/sshd /bin/bash /usr/bin/passwd" domain, unless
 423  * explicitly specified by "initialize_domain".
 424  */
 425 static LIST_HEAD(tomoyo_domain_keeper_list);
 426 static DECLARE_RWSEM(tomoyo_domain_keeper_list_lock);
 427
 428 /**
 429  * tomoyo_update_domain_keeper_entry - Update "struct tomoyo_domain_keeper_entry" list.
 430  *
 431  * @domainname: The name of domain.
 432  * @program:    The name of program. May be NULL.
 433  * @is_not:     True if it is "no_keep_domain" entry.
 434  * @is_delete:  True if it is a delete request.
 435  *
 436  * Returns 0 on success, negative value otherwise.
 437  *
 438  * Caller holds tomoyo_read_lock().
 439  */
 440 static int tomoyo_update_domain_keeper_entry(const char *domainname,
 441                                              const char *program,
 442                                              const bool is_not,
 443                                              const bool is_delete)
 444 {
 445         struct tomoyo_domain_keeper_entry *new_entry;
 446         struct tomoyo_domain_keeper_entry *ptr;
 447         const struct tomoyo_path_info *saved_domainname;
 448         const struct tomoyo_path_info *saved_program = NULL;
 449         int error = -ENOMEM;
 450         bool is_last_name = false;
 451
 452         if (!tomoyo_is_domain_def(domainname) &&
 453             tomoyo_is_correct_path(domainname, 1, -1, -1, __func__))
 454                 is_last_name = true;
 455         else if (!tomoyo_is_correct_domain(domainname, __func__))
 456                 return -EINVAL;
 457         if (program) {
 458                 if (!tomoyo_is_correct_path(program, 1, -1, -1, __func__))
 459                         return -EINVAL;
 460                 saved_program = tomoyo_save_name(program);
 461                 if (!saved_program)
 462                         return -ENOMEM;
 463         }
 464         saved_domainname = tomoyo_save_name(domainname);
 465         if (!saved_domainname)
 466                 return -ENOMEM;
 467         down_write(&tomoyo_domain_keeper_list_lock);
 468         list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
 469                 if (ptr->is_not != is_not ||
 470                     ptr->domainname != saved_domainname ||
 471                     ptr->program != saved_program)
 472                         continue;
 473                 ptr->is_deleted = is_delete;
 474                 error = 0;
 475                 goto out;
 476         }
 477         if (is_delete) {
 478                 error = -ENOENT;
 479                 goto out;
 480         }
 481         new_entry = tomoyo_alloc_element(sizeof(*new_entry));
 482         if (!new_entry)
 483                 goto out;
 484         new_entry->domainname = saved_domainname;
 485         new_entry->program = saved_program;
 486         new_entry->is_not = is_not;
 487         new_entry->is_last_name = is_last_name;
 488         list_add_tail_rcu(&new_entry->list, &tomoyo_domain_keeper_list);
 489         error = 0;
 490  out:
 491         up_write(&tomoyo_domain_keeper_list_lock);
 492         return error;
 493 }
 494
 495 /**
 496  * tomoyo_write_domain_keeper_policy - Write "struct tomoyo_domain_keeper_entry" list.
 497  *
 498  * @data:      String to parse.
 499  * @is_not:    True if it is "no_keep_domain" entry.
 500  * @is_delete: True if it is a delete request.
 501  *
 502  * Caller holds tomoyo_read_lock().
 503  */
 504 int tomoyo_write_domain_keeper_policy(char *data, const bool is_not,
 505                                       const bool is_delete)
 506 {
 507         char *cp = strstr(data, " from ");
 508
 509         if (cp) {
 510                 *cp = '\0';
 511                 return tomoyo_update_domain_keeper_entry(cp + 6, data, is_not,
 512                                                          is_delete);
 513         }
 514         return tomoyo_update_domain_keeper_entry(data, NULL, is_not, is_delete);
 515 }
 516
 517 /**
 518  * tomoyo_read_domain_keeper_policy - Read "struct tomoyo_domain_keeper_entry" list.
 519  *
 520  * @head: Pointer to "struct tomoyo_io_buffer".
 521  *
 522  * Returns true on success, false otherwise.
 523  *
 524  * Caller holds tomoyo_read_lock().
 525  */
 526 bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
 527 {
 528         struct list_head *pos;
 529         bool done = true;
 530
 531         list_for_each_cookie(pos, head->read_var2,
 532                              &tomoyo_domain_keeper_list) {
 533                 struct tomoyo_domain_keeper_entry *ptr;
 534                 const char *no;
 535                 const char *from = "";
 536                 const char *program = "";
 537
 538                 ptr = list_entry(pos, struct tomoyo_domain_keeper_entry, list);
 539                 if (ptr->is_deleted)
 540                         continue;
 541                 no = ptr->is_not ? "no_" : "";
 542                 if (ptr->program) {
 543                         from = " from ";
 544                         program = ptr->program->name;
 545                 }
 546                 done = tomoyo_io_printf(head,
 547                                         "%s" TOMOYO_KEYWORD_KEEP_DOMAIN
 548                                         "%s%s%s\n", no, program, from,
 549                                         ptr->domainname->name);
 550                 if (!done)
 551                         break;
 552         }
 553         return done;
 554 }
 555
 556 /**
 557  * tomoyo_is_domain_keeper - Check whether the given program causes domain transition suppression.
 558  *
 559  * @domainname: The name of domain.
 560  * @program:    The name of program.
 561  * @last_name:  The last component of @domainname.
 562  *
 563  * Returns true if executing @program supresses domain transition,
 564  * false otherwise.
 565  *
 566  * Caller holds tomoyo_read_lock().
 567  */
 568 static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
 569                                     const struct tomoyo_path_info *program,
 570                                     const struct tomoyo_path_info *last_name)
 571 {
 572         struct tomoyo_domain_keeper_entry *ptr;
 573         bool flag = false;
 574
 575         list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
 576                 if (ptr->is_deleted)
 577                         continue;
 578                 if (!ptr->is_last_name) {
 579                         if (ptr->domainname != domainname)
 580                                 continue;
 581                 } else {
 582                         if (tomoyo_pathcmp(ptr->domainname, last_name))
 583                                 continue;
 584                 }
 585                 if (ptr->program && tomoyo_pathcmp(ptr->program, program))
 586                         continue;
 587                 if (ptr->is_not) {
 588                         flag = false;
 589                         break;
 590                 }
 591                 flag = true;
 592         }
 593         return flag;
 594 }
 595
 596 /*
 597  * tomoyo_alias_list is used for holding list of symlink's pathnames which are
 598  * allowed to be passed to an execve() request. Normally, the domainname which
 599  * the current process will belong to after execve() succeeds is calculated
 600  * using dereferenced pathnames. But some programs behave differently depending
 601  * on the name passed to argv[0]. For busybox, calculating domainname using
 602  * dereferenced pathnames will cause all programs in the busybox to belong to
 603  * the same domain. Thus, TOMOYO provides a way to allow use of symlink's
 604  * pathname for checking execve()'s permission and calculating domainname which
 605  * the current process will belong to after execve() succeeds.
 606  *
 607  * An entry is added by
 608  *
 609  * # echo 'alias /bin/busybox /bin/cat' > \
 610  *                            /sys/kernel/security/tomoyo/exception_policy
 611  *
 612  * and is deleted by
 613  *
 614  * # echo 'delete alias /bin/busybox /bin/cat' > \
 615  *                            /sys/kernel/security/tomoyo/exception_policy
 616  *
 617  * and all entries are retrieved by
 618  *
 619  * # grep ^alias /sys/kernel/security/tomoyo/exception_policy
 620  *
 621  * In the example above, if /bin/cat is a symlink to /bin/busybox and execution
 622  * of /bin/cat is requested, permission is checked for /bin/cat rather than
 623  * /bin/busybox and domainname which the current process will belong to after
 624  * execve() succeeds is calculated using /bin/cat rather than /bin/busybox .
 625  */
 626 static LIST_HEAD(tomoyo_alias_list);
 627 static DECLARE_RWSEM(tomoyo_alias_list_lock);
 628
 629 /**
 630  * tomoyo_update_alias_entry - Update "struct tomoyo_alias_entry" list.
 631  *
 632  * @original_name: The original program's real name.
 633  * @aliased_name:  The symbolic program's symbolic link's name.
 634  * @is_delete:     True if it is a delete request.
 635  *
 636  * Returns 0 on success, negative value otherwise.
 637  *
 638  * Caller holds tomoyo_read_lock().
 639  */
 640 static int tomoyo_update_alias_entry(const char *original_name,
 641                                      const char *aliased_name,
 642                                      const bool is_delete)
 643 {
 644         struct tomoyo_alias_entry *new_entry;
 645         struct tomoyo_alias_entry *ptr;
 646         const struct tomoyo_path_info *saved_original_name;
 647         const struct tomoyo_path_info *saved_aliased_name;
 648         int error = -ENOMEM;
 649
 650         if (!tomoyo_is_correct_path(original_name, 1, -1, -1, __func__) ||
 651             !tomoyo_is_correct_path(aliased_name, 1, -1, -1, __func__))
 652                 return -EINVAL; /* No patterns allowed. */
 653         saved_original_name = tomoyo_save_name(original_name);
 654         saved_aliased_name = tomoyo_save_name(aliased_name);
 655         if (!saved_original_name || !saved_aliased_name)
 656                 return -ENOMEM;
 657         down_write(&tomoyo_alias_list_lock);
 658         list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 659                 if (ptr->original_name != saved_original_name ||
 660                     ptr->aliased_name != saved_aliased_name)
 661                         continue;
 662                 ptr->is_deleted = is_delete;
 663                 error = 0;
 664                 goto out;
 665         }
 666         if (is_delete) {
 667                 error = -ENOENT;
 668                 goto out;
 669         }
 670         new_entry = tomoyo_alloc_element(sizeof(*new_entry));
 671         if (!new_entry)
 672                 goto out;
 673         new_entry->original_name = saved_original_name;
 674         new_entry->aliased_name = saved_aliased_name;
 675         list_add_tail_rcu(&new_entry->list, &tomoyo_alias_list);
 676         error = 0;
 677  out:
 678         up_write(&tomoyo_alias_list_lock);
 679         return error;
 680 }
 681
 682 /**
 683  * tomoyo_read_alias_policy - Read "struct tomoyo_alias_entry" list.
 684  *
 685  * @head: Pointer to "struct tomoyo_io_buffer".
 686  *
 687  * Returns true on success, false otherwise.
 688  *
 689  * Caller holds tomoyo_read_lock().
 690  */
 691 bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
 692 {
 693         struct list_head *pos;
 694         bool done = true;
 695
 696         list_for_each_cookie(pos, head->read_var2, &tomoyo_alias_list) {
 697                 struct tomoyo_alias_entry *ptr;
 698
 699                 ptr = list_entry(pos, struct tomoyo_alias_entry, list);
 700                 if (ptr->is_deleted)
 701                         continue;
 702                 done = tomoyo_io_printf(head, TOMOYO_KEYWORD_ALIAS "%s %s\n",
 703                                         ptr->original_name->name,
 704                                         ptr->aliased_name->name);
 705                 if (!done)
 706                         break;
 707         }
 708         return done;
 709 }
 710
 711 /**
 712  * tomoyo_write_alias_policy - Write "struct tomoyo_alias_entry" list.
 713  *
 714  * @data:      String to parse.
 715  * @is_delete: True if it is a delete request.
 716  *
 717  * Returns 0 on success, negative value otherwise.
 718  *
 719  * Caller holds tomoyo_read_lock().
 720  */
 721 int tomoyo_write_alias_policy(char *data, const bool is_delete)
 722 {
 723         char *cp = strchr(data, ' ');
 724
 725         if (!cp)
 726                 return -EINVAL;
 727         *cp++ = '\0';
 728         return tomoyo_update_alias_entry(data, cp, is_delete);
 729 }
 730
 731 /**
 732  * tomoyo_find_or_assign_new_domain - Create a domain.
 733  *
 734  * @domainname: The name of domain.
 735  * @profile:    Profile number to assign if the domain was newly created.
 736  *
 737  * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
 738  *
 739  * Caller holds tomoyo_read_lock().
 740  */
 741 struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 742                                                             domainname,
 743                                                             const u8 profile)
 744 {
 745         struct tomoyo_domain_info *domain = NULL;
 746         const struct tomoyo_path_info *saved_domainname;
 747
 748         down_write(&tomoyo_domain_list_lock);
 749         domain = tomoyo_find_domain(domainname);
 750         if (domain)
 751                 goto out;
 752         if (!tomoyo_is_correct_domain(domainname, __func__))
 753                 goto out;
 754         saved_domainname = tomoyo_save_name(domainname);
 755         if (!saved_domainname)
 756                 goto out;
 757         /* Can I reuse memory of deleted domain? */
 758         list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
 759                 struct task_struct *p;
 760                 struct tomoyo_acl_info *ptr;
 761                 bool flag;
 762                 if (!domain->is_deleted ||
 763                     domain->domainname != saved_domainname)
 764                         continue;
 765                 flag = false;
 766                 read_lock(&tasklist_lock);
 767                 for_each_process(p) {
 768                         if (tomoyo_real_domain(p) != domain)
 769                                 continue;
 770                         flag = true;
 771                         break;
 772                 }
 773                 read_unlock(&tasklist_lock);
 774                 if (flag)
 775                         continue;
 776                 list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
 777                         ptr->type |= TOMOYO_ACL_DELETED;
 778                 }
 779                 tomoyo_set_domain_flag(domain, true, domain->flags);
 780                 domain->profile = profile;
 781                 domain->quota_warned = false;
 782                 mb(); /* Avoid out-of-order execution. */
 783                 domain->is_deleted = false;
 784                 goto out;
 785         }
 786         /* No memory reusable. Create using new memory. */
 787         domain = tomoyo_alloc_element(sizeof(*domain));
 788         if (domain) {
 789                 INIT_LIST_HEAD(&domain->acl_info_list);
 790                 domain->domainname = saved_domainname;
 791                 domain->profile = profile;
 792                 list_add_tail_rcu(&domain->list, &tomoyo_domain_list);
 793         }
 794  out:
 795         up_write(&tomoyo_domain_list_lock);
 796         return domain;
 797 }
 798
 799 /**
 800  * tomoyo_find_next_domain - Find a domain.
 801  *
 802  * @bprm: Pointer to "struct linux_binprm".
 803  *
 804  * Returns 0 on success, negative value otherwise.
 805  *
 806  * Caller holds tomoyo_read_lock().
 807  */
 808 int tomoyo_find_next_domain(struct linux_binprm *bprm)
 809 {
 810         /*
 811          * This function assumes that the size of buffer returned by
 812          * tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
 813          */
 814         struct tomoyo_page_buffer *tmp = tomoyo_alloc(sizeof(*tmp));
 815         struct tomoyo_domain_info *old_domain = tomoyo_domain();
 816         struct tomoyo_domain_info *domain = NULL;
 817         const char *old_domain_name = old_domain->domainname->name;
 818         const char *original_name = bprm->filename;
 819         char *new_domain_name = NULL;
 820         char *real_program_name = NULL;
 821         char *symlink_program_name = NULL;
 822         const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
 823         const bool is_enforce = (mode == 3);
 824         int retval = -ENOMEM;
 825         struct tomoyo_path_info r; /* real name */
 826         struct tomoyo_path_info s; /* symlink name */
 827         struct tomoyo_path_info l; /* last name */
 828         static bool initialized;
 829
 830         if (!tmp)
 831                 goto out;
 832
 833         if (!initialized) {
 834                 /*
 835                  * Built-in initializers. This is needed because policies are
 836                  * not loaded until starting /sbin/init.
 837                  */
 838                 tomoyo_update_domain_initializer_entry(NULL, "/sbin/hotplug",
 839                                                        false, false);
 840                 tomoyo_update_domain_initializer_entry(NULL, "/sbin/modprobe",
 841                                                        false, false);
 842                 initialized = true;
 843         }
 844
 845         /* Get tomoyo_realpath of program. */
 846         retval = -ENOENT;
 847         /* I hope tomoyo_realpath() won't fail with -ENOMEM. */
 848         real_program_name = tomoyo_realpath(original_name);
 849         if (!real_program_name)
 850                 goto out;
 851         /* Get tomoyo_realpath of symbolic link. */
 852         symlink_program_name = tomoyo_realpath_nofollow(original_name);
 853         if (!symlink_program_name)
 854                 goto out;
 855
 856         r.name = real_program_name;
 857         tomoyo_fill_path_info(&r);
 858         s.name = symlink_program_name;
 859         tomoyo_fill_path_info(&s);
 860         l.name = tomoyo_get_last_name(old_domain);
 861         tomoyo_fill_path_info(&l);
 862
 863         /* Check 'alias' directive. */
 864         if (tomoyo_pathcmp(&r, &s)) {
 865                 struct tomoyo_alias_entry *ptr;
 866                 /* Is this program allowed to be called via symbolic links? */
 867                 list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 868                         if (ptr->is_deleted ||
 869                             tomoyo_pathcmp(&r, ptr->original_name) ||
 870                             tomoyo_pathcmp(&s, ptr->aliased_name))
 871                                 continue;
 872                         memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
 873                         strncpy(real_program_name, ptr->aliased_name->name,
 874                                 TOMOYO_MAX_PATHNAME_LEN - 1);
 875                         tomoyo_fill_path_info(&r);
 876                         break;
 877                 }
 878         }
 879
 880         /* Check execute permission. */
 881         retval = tomoyo_check_exec_perm(old_domain, &r);
 882         if (retval < 0)
 883                 goto out;
 884
 885         new_domain_name = tmp->buffer;
 886         if (tomoyo_is_domain_initializer(old_domain->domainname, &r, &l)) {
 887                 /* Transit to the child of tomoyo_kernel_domain domain. */
 888                 snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
 889                          TOMOYO_ROOT_NAME " " "%s", real_program_name);
 890         } else if (old_domain == &tomoyo_kernel_domain &&
 891                    !tomoyo_policy_loaded) {
 892                 /*
 893                  * Needn't to transit from kernel domain before starting
 894                  * /sbin/init. But transit from kernel domain if executing
 895                  * initializers because they might start before /sbin/init.
 896                  */
 897                 domain = old_domain;
 898         } else if (tomoyo_is_domain_keeper(old_domain->domainname, &r, &l)) {
 899                 /* Keep current domain. */
 900                 domain = old_domain;
 901         } else {
 902                 /* Normal domain transition. */
 903                 snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
 904                          "%s %s", old_domain_name, real_program_name);
 905         }
 906         if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
 907                 goto done;
 908         domain = tomoyo_find_domain(new_domain_name);
 909         if (domain)
 910                 goto done;
 911         if (is_enforce)
 912                 goto done;
 913         domain = tomoyo_find_or_assign_new_domain(new_domain_name,
 914                                                   old_domain->profile);
 915  done:
 916         if (domain)
 917                 goto out;
 918         printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
 919                new_domain_name);
 920         if (is_enforce)
 921                 retval = -EPERM;
 922         else
 923                 tomoyo_set_domain_flag(old_domain, false,
 924                                        TOMOYO_DOMAIN_FLAGS_TRANSITION_FAILED);
 925  out:
 926         if (!domain)
 927                 domain = old_domain;
 928         bprm->cred->security = domain;
 929         tomoyo_free(real_program_name);
 930         tomoyo_free(symlink_program_name);
 931         tomoyo_free(tmp);
 932         return retval;
 933 }