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
  62 /*
  63  * tomoyo_domain_initializer_entry is a structure which is used for holding
  64  * "initialize_domain" and "no_initialize_domain" entries.
  65  * It has following fields.
  66  *
  67  *  (1) "list" which is linked to tomoyo_domain_initializer_list .
  68  *  (2) "domainname" which is "a domainname" or "the last component of a
  69  *      domainname". This field is NULL if "from" clause is not specified.
  70  *  (3) "program" which is a program's pathname.
  71  *  (4) "is_deleted" is a bool which is true if marked as deleted, false
  72  *      otherwise.
  73  *  (5) "is_not" is a bool which is true if "no_initialize_domain", false
  74  *      otherwise.
  75  *  (6) "is_last_name" is a bool which is true if "domainname" is "the last
  76  *      component of a domainname", false otherwise.
  77  */
  78 struct tomoyo_domain_initializer_entry {
  79         struct list_head list;
  80         const struct tomoyo_path_info *domainname;    /* This may be NULL */
  81         const struct tomoyo_path_info *program;
  82         bool is_deleted;
  83         bool is_not;       /* True if this entry is "no_initialize_domain".  */
  84         /* True if the domainname is tomoyo_get_last_name(). */
  85         bool is_last_name;
  86 };
  87
  88 /*
  89  * tomoyo_domain_keeper_entry is a structure which is used for holding
  90  * "keep_domain" and "no_keep_domain" entries.
  91  * It has following fields.
  92  *
  93  *  (1) "list" which is linked to tomoyo_domain_keeper_list .
  94  *  (2) "domainname" which is "a domainname" or "the last component of a
  95  *      domainname".
  96  *  (3) "program" which is a program's pathname.
  97  *      This field is NULL if "from" clause is not specified.
  98  *  (4) "is_deleted" is a bool which is true if marked as deleted, false
  99  *      otherwise.
 100  *  (5) "is_not" is a bool which is true if "no_initialize_domain", false
 101  *      otherwise.
 102  *  (6) "is_last_name" is a bool which is true if "domainname" is "the last
 103  *      component of a domainname", false otherwise.
 104  */
 105 struct tomoyo_domain_keeper_entry {
 106         struct list_head list;
 107         const struct tomoyo_path_info *domainname;
 108         const struct tomoyo_path_info *program;       /* This may be NULL */
 109         bool is_deleted;
 110         bool is_not;       /* True if this entry is "no_keep_domain".        */
 111         /* True if the domainname is tomoyo_get_last_name(). */
 112         bool is_last_name;
 113 };
 114
 115 /*
 116  * tomoyo_alias_entry is a structure which is used for holding "alias" entries.
 117  * It has following fields.
 118  *
 119  *  (1) "list" which is linked to tomoyo_alias_list .
 120  *  (2) "original_name" which is a dereferenced pathname.
 121  *  (3) "aliased_name" which is a symlink's pathname.
 122  *  (4) "is_deleted" is a bool which is true if marked as deleted, false
 123  *      otherwise.
 124  */
 125 struct tomoyo_alias_entry {
 126         struct list_head list;
 127         const struct tomoyo_path_info *original_name;
 128         const struct tomoyo_path_info *aliased_name;
 129         bool is_deleted;
 130 };
 131
 132 /**
 133  * tomoyo_set_domain_flag - Set or clear domain's attribute flags.
 134  *
 135  * @domain:    Pointer to "struct tomoyo_domain_info".
 136  * @is_delete: True if it is a delete request.
 137  * @flags:     Flags to set or clear.
 138  *
 139  * Returns nothing.
 140  */
 141 void tomoyo_set_domain_flag(struct tomoyo_domain_info *domain,
 142                             const bool is_delete, const u8 flags)
 143 {
 144         /* We need to serialize because this is bitfield operation. */
 145         static DEFINE_SPINLOCK(lock);
 146         spin_lock(&lock);
 147         if (!is_delete)
 148                 domain->flags |= flags;
 149         else
 150                 domain->flags &= ~flags;
 151         spin_unlock(&lock);
 152 }
 153
 154 /**
 155  * tomoyo_get_last_name - Get last component of a domainname.
 156  *
 157  * @domain: Pointer to "struct tomoyo_domain_info".
 158  *
 159  * Returns the last component of the domainname.
 160  */
 161 const char *tomoyo_get_last_name(const struct tomoyo_domain_info *domain)
 162 {
 163         const char *cp0 = domain->domainname->name;
 164         const char *cp1 = strrchr(cp0, ' ');
 165
 166         if (cp1)
 167                 return cp1 + 1;
 168         return cp0;
 169 }
 170
 171 /*
 172  * tomoyo_domain_initializer_list is used for holding list of programs which
 173  * triggers reinitialization of domainname. Normally, a domainname is
 174  * monotonically getting longer. But sometimes, we restart daemon programs.
 175  * It would be convenient for us that "a daemon started upon system boot" and
 176  * "the daemon restarted from console" belong to the same domain. Thus, TOMOYO
 177  * provides a way to shorten domainnames.
 178  *
 179  * An entry is added by
 180  *
 181  * # echo 'initialize_domain /usr/sbin/httpd' > \
 182  *                               /sys/kernel/security/tomoyo/exception_policy
 183  *
 184  * and is deleted by
 185  *
 186  * # echo 'delete initialize_domain /usr/sbin/httpd' > \
 187  *                               /sys/kernel/security/tomoyo/exception_policy
 188  *
 189  * and all entries are retrieved by
 190  *
 191  * # grep ^initialize_domain /sys/kernel/security/tomoyo/exception_policy
 192  *
 193  * In the example above, /usr/sbin/httpd will belong to
 194  * "<kernel> /usr/sbin/httpd" domain.
 195  *
 196  * You may specify a domainname using "from" keyword.
 197  * "initialize_domain /usr/sbin/httpd from <kernel> /etc/rc.d/init.d/httpd"
 198  * will cause "/usr/sbin/httpd" executed from "<kernel> /etc/rc.d/init.d/httpd"
 199  * domain to belong to "<kernel> /usr/sbin/httpd" domain.
 200  *
 201  * You may add "no_" prefix to "initialize_domain".
 202  * "initialize_domain /usr/sbin/httpd" and
 203  * "no_initialize_domain /usr/sbin/httpd from <kernel> /etc/rc.d/init.d/httpd"
 204  * will cause "/usr/sbin/httpd" to belong to "<kernel> /usr/sbin/httpd" domain
 205  * unless executed from "<kernel> /etc/rc.d/init.d/httpd" domain.
 206  */
 207 static LIST_HEAD(tomoyo_domain_initializer_list);
 208
 209 /**
 210  * tomoyo_update_domain_initializer_entry - Update "struct tomoyo_domain_initializer_entry" list.
 211  *
 212  * @domainname: The name of domain. May be NULL.
 213  * @program:    The name of program.
 214  * @is_not:     True if it is "no_initialize_domain" entry.
 215  * @is_delete:  True if it is a delete request.
 216  *
 217  * Returns 0 on success, negative value otherwise.
 218  *
 219  * Caller holds tomoyo_read_lock().
 220  */
 221 static int tomoyo_update_domain_initializer_entry(const char *domainname,
 222                                                   const char *program,
 223                                                   const bool is_not,
 224                                                   const bool is_delete)
 225 {
 226         struct tomoyo_domain_initializer_entry *new_entry;
 227         struct tomoyo_domain_initializer_entry *ptr;
 228         const struct tomoyo_path_info *saved_program;
 229         const struct tomoyo_path_info *saved_domainname = NULL;
 230         int error = -ENOMEM;
 231         bool is_last_name = false;
 232
 233         if (!tomoyo_is_correct_path(program, 1, -1, -1, __func__))
 234                 return -EINVAL; /* No patterns allowed. */
 235         if (domainname) {
 236                 if (!tomoyo_is_domain_def(domainname) &&
 237                     tomoyo_is_correct_path(domainname, 1, -1, -1, __func__))
 238                         is_last_name = true;
 239                 else if (!tomoyo_is_correct_domain(domainname, __func__))
 240                         return -EINVAL;
 241                 saved_domainname = tomoyo_save_name(domainname);
 242                 if (!saved_domainname)
 243                         return -ENOMEM;
 244         }
 245         saved_program = tomoyo_save_name(program);
 246         if (!saved_program)
 247                 return -ENOMEM;
 248         new_entry = kmalloc(sizeof(*new_entry), GFP_KERNEL);
 249         mutex_lock(&tomoyo_policy_lock);
 250         list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, list) {
 251                 if (ptr->is_not != is_not ||
 252                     ptr->domainname != saved_domainname ||
 253                     ptr->program != saved_program)
 254                         continue;
 255                 ptr->is_deleted = is_delete;
 256                 error = 0;
 257                 goto out;
 258         }
 259         if (is_delete) {
 260                 error = -ENOENT;
 261                 goto out;
 262         }
 263         if (!tomoyo_memory_ok(new_entry))
 264                 goto out;
 265         new_entry->domainname = saved_domainname;
 266         new_entry->program = saved_program;
 267         new_entry->is_not = is_not;
 268         new_entry->is_last_name = is_last_name;
 269         list_add_tail_rcu(&new_entry->list, &tomoyo_domain_initializer_list);
 270         new_entry = NULL;
 271         error = 0;
 272  out:
 273         mutex_unlock(&tomoyo_policy_lock);
 274         kfree(new_entry);
 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
 427 /**
 428  * tomoyo_update_domain_keeper_entry - Update "struct tomoyo_domain_keeper_entry" list.
 429  *
 430  * @domainname: The name of domain.
 431  * @program:    The name of program. May be NULL.
 432  * @is_not:     True if it is "no_keep_domain" entry.
 433  * @is_delete:  True if it is a delete request.
 434  *
 435  * Returns 0 on success, negative value otherwise.
 436  *
 437  * Caller holds tomoyo_read_lock().
 438  */
 439 static int tomoyo_update_domain_keeper_entry(const char *domainname,
 440                                              const char *program,
 441                                              const bool is_not,
 442                                              const bool is_delete)
 443 {
 444         struct tomoyo_domain_keeper_entry *new_entry;
 445         struct tomoyo_domain_keeper_entry *ptr;
 446         const struct tomoyo_path_info *saved_domainname;
 447         const struct tomoyo_path_info *saved_program = NULL;
 448         int error = -ENOMEM;
 449         bool is_last_name = false;
 450
 451         if (!tomoyo_is_domain_def(domainname) &&
 452             tomoyo_is_correct_path(domainname, 1, -1, -1, __func__))
 453                 is_last_name = true;
 454         else if (!tomoyo_is_correct_domain(domainname, __func__))
 455                 return -EINVAL;
 456         if (program) {
 457                 if (!tomoyo_is_correct_path(program, 1, -1, -1, __func__))
 458                         return -EINVAL;
 459                 saved_program = tomoyo_save_name(program);
 460                 if (!saved_program)
 461                         return -ENOMEM;
 462         }
 463         saved_domainname = tomoyo_save_name(domainname);
 464         if (!saved_domainname)
 465                 return -ENOMEM;
 466         new_entry = kmalloc(sizeof(*new_entry), GFP_KERNEL);
 467         mutex_lock(&tomoyo_policy_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         if (!tomoyo_memory_ok(new_entry))
 482                 goto out;
 483         new_entry->domainname = saved_domainname;
 484         new_entry->program = saved_program;
 485         new_entry->is_not = is_not;
 486         new_entry->is_last_name = is_last_name;
 487         list_add_tail_rcu(&new_entry->list, &tomoyo_domain_keeper_list);
 488         new_entry = NULL;
 489         error = 0;
 490  out:
 491         mutex_unlock(&tomoyo_policy_lock);
 492         kfree(new_entry);
 493         return error;
 494 }
 495
 496 /**
 497  * tomoyo_write_domain_keeper_policy - Write "struct tomoyo_domain_keeper_entry" list.
 498  *
 499  * @data:      String to parse.
 500  * @is_not:    True if it is "no_keep_domain" entry.
 501  * @is_delete: True if it is a delete request.
 502  *
 503  * Caller holds tomoyo_read_lock().
 504  */
 505 int tomoyo_write_domain_keeper_policy(char *data, const bool is_not,
 506                                       const bool is_delete)
 507 {
 508         char *cp = strstr(data, " from ");
 509
 510         if (cp) {
 511                 *cp = '\0';
 512                 return tomoyo_update_domain_keeper_entry(cp + 6, data, is_not,
 513                                                          is_delete);
 514         }
 515         return tomoyo_update_domain_keeper_entry(data, NULL, is_not, is_delete);
 516 }
 517
 518 /**
 519  * tomoyo_read_domain_keeper_policy - Read "struct tomoyo_domain_keeper_entry" list.
 520  *
 521  * @head: Pointer to "struct tomoyo_io_buffer".
 522  *
 523  * Returns true on success, false otherwise.
 524  *
 525  * Caller holds tomoyo_read_lock().
 526  */
 527 bool tomoyo_read_domain_keeper_policy(struct tomoyo_io_buffer *head)
 528 {
 529         struct list_head *pos;
 530         bool done = true;
 531
 532         list_for_each_cookie(pos, head->read_var2,
 533                              &tomoyo_domain_keeper_list) {
 534                 struct tomoyo_domain_keeper_entry *ptr;
 535                 const char *no;
 536                 const char *from = "";
 537                 const char *program = "";
 538
 539                 ptr = list_entry(pos, struct tomoyo_domain_keeper_entry, list);
 540                 if (ptr->is_deleted)
 541                         continue;
 542                 no = ptr->is_not ? "no_" : "";
 543                 if (ptr->program) {
 544                         from = " from ";
 545                         program = ptr->program->name;
 546                 }
 547                 done = tomoyo_io_printf(head,
 548                                         "%s" TOMOYO_KEYWORD_KEEP_DOMAIN
 549                                         "%s%s%s\n", no, program, from,
 550                                         ptr->domainname->name);
 551                 if (!done)
 552                         break;
 553         }
 554         return done;
 555 }
 556
 557 /**
 558  * tomoyo_is_domain_keeper - Check whether the given program causes domain transition suppression.
 559  *
 560  * @domainname: The name of domain.
 561  * @program:    The name of program.
 562  * @last_name:  The last component of @domainname.
 563  *
 564  * Returns true if executing @program supresses domain transition,
 565  * false otherwise.
 566  *
 567  * Caller holds tomoyo_read_lock().
 568  */
 569 static bool tomoyo_is_domain_keeper(const struct tomoyo_path_info *domainname,
 570                                     const struct tomoyo_path_info *program,
 571                                     const struct tomoyo_path_info *last_name)
 572 {
 573         struct tomoyo_domain_keeper_entry *ptr;
 574         bool flag = false;
 575
 576         list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
 577                 if (ptr->is_deleted)
 578                         continue;
 579                 if (!ptr->is_last_name) {
 580                         if (ptr->domainname != domainname)
 581                                 continue;
 582                 } else {
 583                         if (tomoyo_pathcmp(ptr->domainname, last_name))
 584                                 continue;
 585                 }
 586                 if (ptr->program && tomoyo_pathcmp(ptr->program, program))
 587                         continue;
 588                 if (ptr->is_not) {
 589                         flag = false;
 590                         break;
 591                 }
 592                 flag = true;
 593         }
 594         return flag;
 595 }
 596
 597 /*
 598  * tomoyo_alias_list is used for holding list of symlink's pathnames which are
 599  * allowed to be passed to an execve() request. Normally, the domainname which
 600  * the current process will belong to after execve() succeeds is calculated
 601  * using dereferenced pathnames. But some programs behave differently depending
 602  * on the name passed to argv[0]. For busybox, calculating domainname using
 603  * dereferenced pathnames will cause all programs in the busybox to belong to
 604  * the same domain. Thus, TOMOYO provides a way to allow use of symlink's
 605  * pathname for checking execve()'s permission and calculating domainname which
 606  * the current process will belong to after execve() succeeds.
 607  *
 608  * An entry is added by
 609  *
 610  * # echo 'alias /bin/busybox /bin/cat' > \
 611  *                            /sys/kernel/security/tomoyo/exception_policy
 612  *
 613  * and is deleted by
 614  *
 615  * # echo 'delete alias /bin/busybox /bin/cat' > \
 616  *                            /sys/kernel/security/tomoyo/exception_policy
 617  *
 618  * and all entries are retrieved by
 619  *
 620  * # grep ^alias /sys/kernel/security/tomoyo/exception_policy
 621  *
 622  * In the example above, if /bin/cat is a symlink to /bin/busybox and execution
 623  * of /bin/cat is requested, permission is checked for /bin/cat rather than
 624  * /bin/busybox and domainname which the current process will belong to after
 625  * execve() succeeds is calculated using /bin/cat rather than /bin/busybox .
 626  */
 627 static LIST_HEAD(tomoyo_alias_list);
 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         new_entry = kmalloc(sizeof(*new_entry), GFP_KERNEL);
 658         mutex_lock(&tomoyo_policy_lock);
 659         list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 660                 if (ptr->original_name != saved_original_name ||
 661                     ptr->aliased_name != saved_aliased_name)
 662                         continue;
 663                 ptr->is_deleted = is_delete;
 664                 error = 0;
 665                 goto out;
 666         }
 667         if (is_delete) {
 668                 error = -ENOENT;
 669                 goto out;
 670         }
 671         if (!tomoyo_memory_ok(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         new_entry = NULL;
 677         error = 0;
 678  out:
 679         mutex_unlock(&tomoyo_policy_lock);
 680         kfree(new_entry);
 681         return error;
 682 }
 683
 684 /**
 685  * tomoyo_read_alias_policy - Read "struct tomoyo_alias_entry" list.
 686  *
 687  * @head: Pointer to "struct tomoyo_io_buffer".
 688  *
 689  * Returns true on success, false otherwise.
 690  *
 691  * Caller holds tomoyo_read_lock().
 692  */
 693 bool tomoyo_read_alias_policy(struct tomoyo_io_buffer *head)
 694 {
 695         struct list_head *pos;
 696         bool done = true;
 697
 698         list_for_each_cookie(pos, head->read_var2, &tomoyo_alias_list) {
 699                 struct tomoyo_alias_entry *ptr;
 700
 701                 ptr = list_entry(pos, struct tomoyo_alias_entry, list);
 702                 if (ptr->is_deleted)
 703                         continue;
 704                 done = tomoyo_io_printf(head, TOMOYO_KEYWORD_ALIAS "%s %s\n",
 705                                         ptr->original_name->name,
 706                                         ptr->aliased_name->name);
 707                 if (!done)
 708                         break;
 709         }
 710         return done;
 711 }
 712
 713 /**
 714  * tomoyo_write_alias_policy - Write "struct tomoyo_alias_entry" list.
 715  *
 716  * @data:      String to parse.
 717  * @is_delete: True if it is a delete request.
 718  *
 719  * Returns 0 on success, negative value otherwise.
 720  *
 721  * Caller holds tomoyo_read_lock().
 722  */
 723 int tomoyo_write_alias_policy(char *data, const bool is_delete)
 724 {
 725         char *cp = strchr(data, ' ');
 726
 727         if (!cp)
 728                 return -EINVAL;
 729         *cp++ = '\0';
 730         return tomoyo_update_alias_entry(data, cp, is_delete);
 731 }
 732
 733 /**
 734  * tomoyo_find_or_assign_new_domain - Create a domain.
 735  *
 736  * @domainname: The name of domain.
 737  * @profile:    Profile number to assign if the domain was newly created.
 738  *
 739  * Returns pointer to "struct tomoyo_domain_info" on success, NULL otherwise.
 740  *
 741  * Caller holds tomoyo_read_lock().
 742  */
 743 struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 744                                                             domainname,
 745                                                             const u8 profile)
 746 {
 747         struct tomoyo_domain_info *domain;
 748         const struct tomoyo_path_info *saved_domainname;
 749
 750         mutex_lock(&tomoyo_policy_lock);
 751         domain = tomoyo_find_domain(domainname);
 752         if (domain)
 753                 goto out;
 754         if (!tomoyo_is_correct_domain(domainname, __func__))
 755                 goto out;
 756         saved_domainname = tomoyo_save_name(domainname);
 757         if (!saved_domainname)
 758                 goto out;
 759         domain = kmalloc(sizeof(*domain), GFP_KERNEL);
 760         if (tomoyo_memory_ok(domain)) {
 761                 INIT_LIST_HEAD(&domain->acl_info_list);
 762                 domain->domainname = saved_domainname;
 763                 domain->profile = profile;
 764                 list_add_tail_rcu(&domain->list, &tomoyo_domain_list);
 765         } else {
 766                 kfree(domain);
 767                 domain = NULL;
 768         }
 769
 770  out:
 771         mutex_unlock(&tomoyo_policy_lock);
 772         return domain;
 773 }
 774
 775 /**
 776  * tomoyo_find_next_domain - Find a domain.
 777  *
 778  * @bprm: Pointer to "struct linux_binprm".
 779  *
 780  * Returns 0 on success, negative value otherwise.
 781  *
 782  * Caller holds tomoyo_read_lock().
 783  */
 784 int tomoyo_find_next_domain(struct linux_binprm *bprm)
 785 {
 786         /*
 787          * This function assumes that the size of buffer returned by
 788          * tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
 789          */
 790         struct tomoyo_page_buffer *tmp = tomoyo_alloc(sizeof(*tmp));
 791         struct tomoyo_domain_info *old_domain = tomoyo_domain();
 792         struct tomoyo_domain_info *domain = NULL;
 793         const char *old_domain_name = old_domain->domainname->name;
 794         const char *original_name = bprm->filename;
 795         char *new_domain_name = NULL;
 796         char *real_program_name = NULL;
 797         char *symlink_program_name = NULL;
 798         const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
 799         const bool is_enforce = (mode == 3);
 800         int retval = -ENOMEM;
 801         struct tomoyo_path_info r; /* real name */
 802         struct tomoyo_path_info s; /* symlink name */
 803         struct tomoyo_path_info l; /* last name */
 804         static bool initialized;
 805
 806         if (!tmp)
 807                 goto out;
 808
 809         if (!initialized) {
 810                 /*
 811                  * Built-in initializers. This is needed because policies are
 812                  * not loaded until starting /sbin/init.
 813                  */
 814                 tomoyo_update_domain_initializer_entry(NULL, "/sbin/hotplug",
 815                                                        false, false);
 816                 tomoyo_update_domain_initializer_entry(NULL, "/sbin/modprobe",
 817                                                        false, false);
 818                 initialized = true;
 819         }
 820
 821         /* Get tomoyo_realpath of program. */
 822         retval = -ENOENT;
 823         /* I hope tomoyo_realpath() won't fail with -ENOMEM. */
 824         real_program_name = tomoyo_realpath(original_name);
 825         if (!real_program_name)
 826                 goto out;
 827         /* Get tomoyo_realpath of symbolic link. */
 828         symlink_program_name = tomoyo_realpath_nofollow(original_name);
 829         if (!symlink_program_name)
 830                 goto out;
 831
 832         r.name = real_program_name;
 833         tomoyo_fill_path_info(&r);
 834         s.name = symlink_program_name;
 835         tomoyo_fill_path_info(&s);
 836         l.name = tomoyo_get_last_name(old_domain);
 837         tomoyo_fill_path_info(&l);
 838
 839         /* Check 'alias' directive. */
 840         if (tomoyo_pathcmp(&r, &s)) {
 841                 struct tomoyo_alias_entry *ptr;
 842                 /* Is this program allowed to be called via symbolic links? */
 843                 list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 844                         if (ptr->is_deleted ||
 845                             tomoyo_pathcmp(&r, ptr->original_name) ||
 846                             tomoyo_pathcmp(&s, ptr->aliased_name))
 847                                 continue;
 848                         memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
 849                         strncpy(real_program_name, ptr->aliased_name->name,
 850                                 TOMOYO_MAX_PATHNAME_LEN - 1);
 851                         tomoyo_fill_path_info(&r);
 852                         break;
 853                 }
 854         }
 855
 856         /* Check execute permission. */
 857         retval = tomoyo_check_exec_perm(old_domain, &r);
 858         if (retval < 0)
 859                 goto out;
 860
 861         new_domain_name = tmp->buffer;
 862         if (tomoyo_is_domain_initializer(old_domain->domainname, &r, &l)) {
 863                 /* Transit to the child of tomoyo_kernel_domain domain. */
 864                 snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
 865                          TOMOYO_ROOT_NAME " " "%s", real_program_name);
 866         } else if (old_domain == &tomoyo_kernel_domain &&
 867                    !tomoyo_policy_loaded) {
 868                 /*
 869                  * Needn't to transit from kernel domain before starting
 870                  * /sbin/init. But transit from kernel domain if executing
 871                  * initializers because they might start before /sbin/init.
 872                  */
 873                 domain = old_domain;
 874         } else if (tomoyo_is_domain_keeper(old_domain->domainname, &r, &l)) {
 875                 /* Keep current domain. */
 876                 domain = old_domain;
 877         } else {
 878                 /* Normal domain transition. */
 879                 snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
 880                          "%s %s", old_domain_name, real_program_name);
 881         }
 882         if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
 883                 goto done;
 884         domain = tomoyo_find_domain(new_domain_name);
 885         if (domain)
 886                 goto done;
 887         if (is_enforce)
 888                 goto done;
 889         domain = tomoyo_find_or_assign_new_domain(new_domain_name,
 890                                                   old_domain->profile);
 891  done:
 892         if (domain)
 893                 goto out;
 894         printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
 895                new_domain_name);
 896         if (is_enforce)
 897                 retval = -EPERM;
 898         else
 899                 tomoyo_set_domain_flag(old_domain, false,
 900                                        TOMOYO_DOMAIN_FLAGS_TRANSITION_FAILED);
 901  out:
 902         if (!domain)
 903                 domain = old_domain;
 904         bprm->cred->security = domain;
 905         tomoyo_free(real_program_name);
 906         tomoyo_free(symlink_program_name);
 907         tomoyo_free(tmp);
 908         return retval;
 909 }