security/tomoyo/tomoyo.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * security/tomoyo/tomoyo.c
   4  *
   5  * Copyright (C) 2005-2011  NTT DATA CORPORATION
   6  */
   7
   8 #include <linux/lsm_hooks.h>
   9 #include <uapi/linux/lsm.h>
  10 #include "common.h"
  11
  12 /**
  13  * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
  14  *
  15  * Returns pointer to "struct tomoyo_domain_info" for current thread.
  16  */
  17 struct tomoyo_domain_info *tomoyo_domain(void)
  18 {
  19         struct tomoyo_task *s = tomoyo_task(current);
  20
  21         if (s->old_domain_info && !current->in_execve) {
  22                 atomic_dec(&s->old_domain_info->users);
  23                 s->old_domain_info = NULL;
  24         }
  25         return s->domain_info;
  26 }
  27
  28 /**
  29  * tomoyo_cred_prepare - Target for security_prepare_creds().
  30  *
  31  * @new: Pointer to "struct cred".
  32  * @old: Pointer to "struct cred".
  33  * @gfp: Memory allocation flags.
  34  *
  35  * Returns 0.
  36  */
  37 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
  38                                gfp_t gfp)
  39 {
  40         /* Restore old_domain_info saved by previous execve() request. */
  41         struct tomoyo_task *s = tomoyo_task(current);
  42
  43         if (s->old_domain_info && !current->in_execve) {
  44                 atomic_dec(&s->domain_info->users);
  45                 s->domain_info = s->old_domain_info;
  46                 s->old_domain_info = NULL;
  47         }
  48         return 0;
  49 }
  50
  51 /**
  52  * tomoyo_bprm_committed_creds - Target for security_bprm_committed_creds().
  53  *
  54  * @bprm: Pointer to "struct linux_binprm".
  55  */
  56 static void tomoyo_bprm_committed_creds(const struct linux_binprm *bprm)
  57 {
  58         /* Clear old_domain_info saved by execve() request. */
  59         struct tomoyo_task *s = tomoyo_task(current);
  60
  61         atomic_dec(&s->old_domain_info->users);
  62         s->old_domain_info = NULL;
  63 }
  64
  65 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
  66 /**
  67  * tomoyo_bprm_creds_for_exec - Target for security_bprm_creds_for_exec().
  68  *
  69  * @bprm: Pointer to "struct linux_binprm".
  70  *
  71  * Returns 0.
  72  */
  73 static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
  74 {
  75         /*
  76          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
  77          * for the first time.
  78          */
  79         if (!tomoyo_policy_loaded)
  80                 tomoyo_load_policy(bprm->filename);
  81         return 0;
  82 }
  83 #endif
  84
  85 /**
  86  * tomoyo_bprm_check_security - Target for security_bprm_check().
  87  *
  88  * @bprm: Pointer to "struct linux_binprm".
  89  *
  90  * Returns 0 on success, negative value otherwise.
  91  */
  92 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
  93 {
  94         struct tomoyo_task *s = tomoyo_task(current);
  95
  96         /*
  97          * Execute permission is checked against pathname passed to execve()
  98          * using current domain.
  99          */
 100         if (!s->old_domain_info) {
 101                 const int idx = tomoyo_read_lock();
 102                 const int err = tomoyo_find_next_domain(bprm);
 103
 104                 tomoyo_read_unlock(idx);
 105                 return err;
 106         }
 107         /*
 108          * Read permission is checked against interpreters using next domain.
 109          */
 110         return tomoyo_check_open_permission(s->domain_info,
 111                                             &bprm->file->f_path, O_RDONLY);
 112 }
 113
 114 /**
 115  * tomoyo_inode_getattr - Target for security_inode_getattr().
 116  *
 117  * @path: Pointer to "struct path".
 118  *
 119  * Returns 0 on success, negative value otherwise.
 120  */
 121 static int tomoyo_inode_getattr(const struct path *path)
 122 {
 123         return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, path, NULL);
 124 }
 125
 126 /**
 127  * tomoyo_path_truncate - Target for security_path_truncate().
 128  *
 129  * @path: Pointer to "struct path".
 130  *
 131  * Returns 0 on success, negative value otherwise.
 132  */
 133 static int tomoyo_path_truncate(const struct path *path)
 134 {
 135         return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
 136 }
 137
 138 /**
 139  * tomoyo_file_truncate - Target for security_file_truncate().
 140  *
 141  * @file: Pointer to "struct file".
 142  *
 143  * Returns 0 on success, negative value otherwise.
 144  */
 145 static int tomoyo_file_truncate(struct file *file)
 146 {
 147         return tomoyo_path_truncate(&file->f_path);
 148 }
 149
 150 /**
 151  * tomoyo_path_unlink - Target for security_path_unlink().
 152  *
 153  * @parent: Pointer to "struct path".
 154  * @dentry: Pointer to "struct dentry".
 155  *
 156  * Returns 0 on success, negative value otherwise.
 157  */
 158 static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
 159 {
 160         struct path path = { .mnt = parent->mnt, .dentry = dentry };
 161
 162         return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
 163 }
 164
 165 /**
 166  * tomoyo_path_mkdir - Target for security_path_mkdir().
 167  *
 168  * @parent: Pointer to "struct path".
 169  * @dentry: Pointer to "struct dentry".
 170  * @mode:   DAC permission mode.
 171  *
 172  * Returns 0 on success, negative value otherwise.
 173  */
 174 static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
 175                              umode_t mode)
 176 {
 177         struct path path = { .mnt = parent->mnt, .dentry = dentry };
 178
 179         return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
 180                                        mode & S_IALLUGO);
 181 }
 182
 183 /**
 184  * tomoyo_path_rmdir - Target for security_path_rmdir().
 185  *
 186  * @parent: Pointer to "struct path".
 187  * @dentry: Pointer to "struct dentry".
 188  *
 189  * Returns 0 on success, negative value otherwise.
 190  */
 191 static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
 192 {
 193         struct path path = { .mnt = parent->mnt, .dentry = dentry };
 194
 195         return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
 196 }
 197
 198 /**
 199  * tomoyo_path_symlink - Target for security_path_symlink().
 200  *
 201  * @parent:   Pointer to "struct path".
 202  * @dentry:   Pointer to "struct dentry".
 203  * @old_name: Symlink's content.
 204  *
 205  * Returns 0 on success, negative value otherwise.
 206  */
 207 static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
 208                                const char *old_name)
 209 {
 210         struct path path = { .mnt = parent->mnt, .dentry = dentry };
 211
 212         return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
 213 }
 214
 215 /**
 216  * tomoyo_path_mknod - Target for security_path_mknod().
 217  *
 218  * @parent: Pointer to "struct path".
 219  * @dentry: Pointer to "struct dentry".
 220  * @mode:   DAC permission mode.
 221  * @dev:    Device attributes.
 222  *
 223  * Returns 0 on success, negative value otherwise.
 224  */
 225 static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
 226                              umode_t mode, unsigned int dev)
 227 {
 228         struct path path = { .mnt = parent->mnt, .dentry = dentry };
 229         int type = TOMOYO_TYPE_CREATE;
 230         const unsigned int perm = mode & S_IALLUGO;
 231
 232         switch (mode & S_IFMT) {
 233         case S_IFCHR:
 234                 type = TOMOYO_TYPE_MKCHAR;
 235                 break;
 236         case S_IFBLK:
 237                 type = TOMOYO_TYPE_MKBLOCK;
 238                 break;
 239         default:
 240                 goto no_dev;
 241         }
 242         return tomoyo_mkdev_perm(type, &path, perm, dev);
 243  no_dev:
 244         switch (mode & S_IFMT) {
 245         case S_IFIFO:
 246                 type = TOMOYO_TYPE_MKFIFO;
 247                 break;
 248         case S_IFSOCK:
 249                 type = TOMOYO_TYPE_MKSOCK;
 250                 break;
 251         }
 252         return tomoyo_path_number_perm(type, &path, perm);
 253 }
 254
 255 /**
 256  * tomoyo_path_link - Target for security_path_link().
 257  *
 258  * @old_dentry: Pointer to "struct dentry".
 259  * @new_dir:    Pointer to "struct path".
 260  * @new_dentry: Pointer to "struct dentry".
 261  *
 262  * Returns 0 on success, negative value otherwise.
 263  */
 264 static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
 265                             struct dentry *new_dentry)
 266 {
 267         struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
 268         struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
 269
 270         return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
 271 }
 272
 273 /**
 274  * tomoyo_path_rename - Target for security_path_rename().
 275  *
 276  * @old_parent: Pointer to "struct path".
 277  * @old_dentry: Pointer to "struct dentry".
 278  * @new_parent: Pointer to "struct path".
 279  * @new_dentry: Pointer to "struct dentry".
 280  * @flags: Rename options.
 281  *
 282  * Returns 0 on success, negative value otherwise.
 283  */
 284 static int tomoyo_path_rename(const struct path *old_parent,
 285                               struct dentry *old_dentry,
 286                               const struct path *new_parent,
 287                               struct dentry *new_dentry,
 288                               const unsigned int flags)
 289 {
 290         struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
 291         struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
 292
 293         if (flags & RENAME_EXCHANGE) {
 294                 const int err = tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path2,
 295                                 &path1);
 296
 297                 if (err)
 298                         return err;
 299         }
 300         return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
 301 }
 302
 303 /**
 304  * tomoyo_file_fcntl - Target for security_file_fcntl().
 305  *
 306  * @file: Pointer to "struct file".
 307  * @cmd:  Command for fcntl().
 308  * @arg:  Argument for @cmd.
 309  *
 310  * Returns 0 on success, negative value otherwise.
 311  */
 312 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 313                              unsigned long arg)
 314 {
 315         if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
 316                 return 0;
 317         return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
 318                                             O_WRONLY | (arg & O_APPEND));
 319 }
 320
 321 /**
 322  * tomoyo_file_open - Target for security_file_open().
 323  *
 324  * @f: Pointer to "struct file".
 325  *
 326  * Returns 0 on success, negative value otherwise.
 327  */
 328 static int tomoyo_file_open(struct file *f)
 329 {
 330         /* Don't check read permission here if called from execve(). */
 331         /* Illogically, FMODE_EXEC is in f_flags, not f_mode. */
 332         if (f->f_flags & __FMODE_EXEC)
 333                 return 0;
 334         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
 335                                             f->f_flags);
 336 }
 337
 338 /**
 339  * tomoyo_file_ioctl - Target for security_file_ioctl().
 340  *
 341  * @file: Pointer to "struct file".
 342  * @cmd:  Command for ioctl().
 343  * @arg:  Argument for @cmd.
 344  *
 345  * Returns 0 on success, negative value otherwise.
 346  */
 347 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
 348                              unsigned long arg)
 349 {
 350         return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
 351 }
 352
 353 /**
 354  * tomoyo_path_chmod - Target for security_path_chmod().
 355  *
 356  * @path: Pointer to "struct path".
 357  * @mode: DAC permission mode.
 358  *
 359  * Returns 0 on success, negative value otherwise.
 360  */
 361 static int tomoyo_path_chmod(const struct path *path, umode_t mode)
 362 {
 363         return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
 364                                        mode & S_IALLUGO);
 365 }
 366
 367 /**
 368  * tomoyo_path_chown - Target for security_path_chown().
 369  *
 370  * @path: Pointer to "struct path".
 371  * @uid:  Owner ID.
 372  * @gid:  Group ID.
 373  *
 374  * Returns 0 on success, negative value otherwise.
 375  */
 376 static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
 377 {
 378         int error = 0;
 379
 380         if (uid_valid(uid))
 381                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
 382                                                 from_kuid(&init_user_ns, uid));
 383         if (!error && gid_valid(gid))
 384                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
 385                                                 from_kgid(&init_user_ns, gid));
 386         return error;
 387 }
 388
 389 /**
 390  * tomoyo_path_chroot - Target for security_path_chroot().
 391  *
 392  * @path: Pointer to "struct path".
 393  *
 394  * Returns 0 on success, negative value otherwise.
 395  */
 396 static int tomoyo_path_chroot(const struct path *path)
 397 {
 398         return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
 399 }
 400
 401 /**
 402  * tomoyo_sb_mount - Target for security_sb_mount().
 403  *
 404  * @dev_name: Name of device file. Maybe NULL.
 405  * @path:     Pointer to "struct path".
 406  * @type:     Name of filesystem type. Maybe NULL.
 407  * @flags:    Mount options.
 408  * @data:     Optional data. Maybe NULL.
 409  *
 410  * Returns 0 on success, negative value otherwise.
 411  */
 412 static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
 413                            const char *type, unsigned long flags, void *data)
 414 {
 415         return tomoyo_mount_permission(dev_name, path, type, flags, data);
 416 }
 417
 418 /**
 419  * tomoyo_sb_umount - Target for security_sb_umount().
 420  *
 421  * @mnt:   Pointer to "struct vfsmount".
 422  * @flags: Unmount options.
 423  *
 424  * Returns 0 on success, negative value otherwise.
 425  */
 426 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
 427 {
 428         struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
 429
 430         return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
 431 }
 432
 433 /**
 434  * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
 435  *
 436  * @old_path: Pointer to "struct path".
 437  * @new_path: Pointer to "struct path".
 438  *
 439  * Returns 0 on success, negative value otherwise.
 440  */
 441 static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
 442 {
 443         return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
 444 }
 445
 446 /**
 447  * tomoyo_socket_listen - Check permission for listen().
 448  *
 449  * @sock:    Pointer to "struct socket".
 450  * @backlog: Backlog parameter.
 451  *
 452  * Returns 0 on success, negative value otherwise.
 453  */
 454 static int tomoyo_socket_listen(struct socket *sock, int backlog)
 455 {
 456         return tomoyo_socket_listen_permission(sock);
 457 }
 458
 459 /**
 460  * tomoyo_socket_connect - Check permission for connect().
 461  *
 462  * @sock:     Pointer to "struct socket".
 463  * @addr:     Pointer to "struct sockaddr".
 464  * @addr_len: Size of @addr.
 465  *
 466  * Returns 0 on success, negative value otherwise.
 467  */
 468 static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
 469                                  int addr_len)
 470 {
 471         return tomoyo_socket_connect_permission(sock, addr, addr_len);
 472 }
 473
 474 /**
 475  * tomoyo_socket_bind - Check permission for bind().
 476  *
 477  * @sock:     Pointer to "struct socket".
 478  * @addr:     Pointer to "struct sockaddr".
 479  * @addr_len: Size of @addr.
 480  *
 481  * Returns 0 on success, negative value otherwise.
 482  */
 483 static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
 484                               int addr_len)
 485 {
 486         return tomoyo_socket_bind_permission(sock, addr, addr_len);
 487 }
 488
 489 /**
 490  * tomoyo_socket_sendmsg - Check permission for sendmsg().
 491  *
 492  * @sock: Pointer to "struct socket".
 493  * @msg:  Pointer to "struct msghdr".
 494  * @size: Size of message.
 495  *
 496  * Returns 0 on success, negative value otherwise.
 497  */
 498 static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
 499                                  int size)
 500 {
 501         return tomoyo_socket_sendmsg_permission(sock, msg, size);
 502 }
 503
 504 struct lsm_blob_sizes tomoyo_blob_sizes __ro_after_init = {
 505         .lbs_task = sizeof(struct tomoyo_task),
 506 };
 507
 508 /**
 509  * tomoyo_task_alloc - Target for security_task_alloc().
 510  *
 511  * @task:        Pointer to "struct task_struct".
 512  * @clone_flags: clone() flags.
 513  *
 514  * Returns 0.
 515  */
 516 static int tomoyo_task_alloc(struct task_struct *task,
 517                              unsigned long clone_flags)
 518 {
 519         struct tomoyo_task *old = tomoyo_task(current);
 520         struct tomoyo_task *new = tomoyo_task(task);
 521
 522         new->domain_info = old->domain_info;
 523         atomic_inc(&new->domain_info->users);
 524         new->old_domain_info = NULL;
 525         return 0;
 526 }
 527
 528 /**
 529  * tomoyo_task_free - Target for security_task_free().
 530  *
 531  * @task: Pointer to "struct task_struct".
 532  */
 533 static void tomoyo_task_free(struct task_struct *task)
 534 {
 535         struct tomoyo_task *s = tomoyo_task(task);
 536
 537         if (s->domain_info) {
 538                 atomic_dec(&s->domain_info->users);
 539                 s->domain_info = NULL;
 540         }
 541         if (s->old_domain_info) {
 542                 atomic_dec(&s->old_domain_info->users);
 543                 s->old_domain_info = NULL;
 544         }
 545 }
 546
 547 static const struct lsm_id tomoyo_lsmid = {
 548         .name = "tomoyo",
 549         .id = LSM_ID_TOMOYO,
 550 };
 551
 552 /*
 553  * tomoyo_security_ops is a "struct security_operations" which is used for
 554  * registering TOMOYO.
 555  */
 556 static struct security_hook_list tomoyo_hooks[] __ro_after_init = {
 557         LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
 558         LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
 559         LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
 560         LSM_HOOK_INIT(task_free, tomoyo_task_free),
 561 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
 562         LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
 563 #endif
 564         LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
 565         LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
 566         LSM_HOOK_INIT(file_open, tomoyo_file_open),
 567         LSM_HOOK_INIT(file_truncate, tomoyo_file_truncate),
 568         LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
 569         LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
 570         LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
 571         LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
 572         LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
 573         LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
 574         LSM_HOOK_INIT(path_link, tomoyo_path_link),
 575         LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
 576         LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
 577         LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
 578         LSM_HOOK_INIT(file_ioctl_compat, tomoyo_file_ioctl),
 579         LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
 580         LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
 581         LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
 582         LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
 583         LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
 584         LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
 585         LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
 586         LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
 587         LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
 588         LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
 589 };
 590
 591 /* Lock for GC. */
 592 DEFINE_SRCU(tomoyo_ss);
 593
 594 int tomoyo_enabled __ro_after_init = 1;
 595
 596 /**
 597  * tomoyo_init - Register TOMOYO Linux as a LSM module.
 598  *
 599  * Returns 0.
 600  */
 601 static int __init tomoyo_init(void)
 602 {
 603         struct tomoyo_task *s = tomoyo_task(current);
 604
 605         /* register ourselves with the security framework */
 606         security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks),
 607                            &tomoyo_lsmid);
 608         pr_info("TOMOYO Linux initialized\n");
 609         s->domain_info = &tomoyo_kernel_domain;
 610         atomic_inc(&tomoyo_kernel_domain.users);
 611         s->old_domain_info = NULL;
 612         tomoyo_mm_init();
 613
 614         return 0;
 615 }
 616
 617 DEFINE_LSM(tomoyo) = {
 618         .name = "tomoyo",
 619         .enabled = &tomoyo_enabled,
 620         .flags = LSM_FLAG_LEGACY_MAJOR,
 621         .blobs = &tomoyo_blob_sizes,
 622         .init = tomoyo_init,
 623 };