xref: /openbmc/linux/security/tomoyo/tomoyo.c (revision 31e67366) 
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 "common.h"
10 
11 /**
12  * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
13  *
14  * Returns pointer to "struct tomoyo_domain_info" for current thread.
15  */
16 struct tomoyo_domain_info *tomoyo_domain(void)
17 {
18 	struct tomoyo_task *s = tomoyo_task(current);
19 
20 	if (s->old_domain_info && !current->in_execve) {
21 		atomic_dec(&s->old_domain_info->users);
22 		s->old_domain_info = NULL;
23 	}
24 	return s->domain_info;
25 }
26 
27 /**
28  * tomoyo_cred_prepare - Target for security_prepare_creds().
29  *
30  * @new: Pointer to "struct cred".
31  * @old: Pointer to "struct cred".
32  * @gfp: Memory allocation flags.
33  *
34  * Returns 0.
35  */
36 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
37 			       gfp_t gfp)
38 {
39 	/* Restore old_domain_info saved by previous execve() request. */
40 	struct tomoyo_task *s = tomoyo_task(current);
41 
42 	if (s->old_domain_info && !current->in_execve) {
43 		atomic_dec(&s->domain_info->users);
44 		s->domain_info = s->old_domain_info;
45 		s->old_domain_info = NULL;
46 	}
47 	return 0;
48 }
49 
50 /**
51  * tomoyo_bprm_committed_creds - Target for security_bprm_committed_creds().
52  *
53  * @bprm: Pointer to "struct linux_binprm".
54  */
55 static void tomoyo_bprm_committed_creds(struct linux_binprm *bprm)
56 {
57 	/* Clear old_domain_info saved by execve() request. */
58 	struct tomoyo_task *s = tomoyo_task(current);
59 
60 	atomic_dec(&s->old_domain_info->users);
61 	s->old_domain_info = NULL;
62 }
63 
64 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
65 /**
66  * tomoyo_bprm_for_exec - Target for security_bprm_creds_for_exec().
67  *
68  * @bprm: Pointer to "struct linux_binprm".
69  *
70  * Returns 0.
71  */
72 static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
73 {
74 	/*
75 	 * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
76 	 * for the first time.
77 	 */
78 	if (!tomoyo_policy_loaded)
79 		tomoyo_load_policy(bprm->filename);
80 	return 0;
81 }
82 #endif
83 
84 /**
85  * tomoyo_bprm_check_security - Target for security_bprm_check().
86  *
87  * @bprm: Pointer to "struct linux_binprm".
88  *
89  * Returns 0 on success, negative value otherwise.
90  */
91 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
92 {
93 	struct tomoyo_task *s = tomoyo_task(current);
94 
95 	/*
96 	 * Execute permission is checked against pathname passed to execve()
97 	 * using current domain.
98 	 */
99 	if (!s->old_domain_info) {
100 		const int idx = tomoyo_read_lock();
101 		const int err = tomoyo_find_next_domain(bprm);
102 
103 		tomoyo_read_unlock(idx);
104 		return err;
105 	}
106 	/*
107 	 * Read permission is checked against interpreters using next domain.
108 	 */
109 	return tomoyo_check_open_permission(s->domain_info,
110 					    &bprm->file->f_path, O_RDONLY);
111 }
112 
113 /**
114  * tomoyo_inode_getattr - Target for security_inode_getattr().
115  *
116  * @mnt:    Pointer to "struct vfsmount".
117  * @dentry: Pointer to "struct dentry".
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_path_unlink - Target for security_path_unlink().
140  *
141  * @parent: Pointer to "struct path".
142  * @dentry: Pointer to "struct dentry".
143  *
144  * Returns 0 on success, negative value otherwise.
145  */
146 static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
147 {
148 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
149 
150 	return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
151 }
152 
153 /**
154  * tomoyo_path_mkdir - Target for security_path_mkdir().
155  *
156  * @parent: Pointer to "struct path".
157  * @dentry: Pointer to "struct dentry".
158  * @mode:   DAC permission mode.
159  *
160  * Returns 0 on success, negative value otherwise.
161  */
162 static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
163 			     umode_t mode)
164 {
165 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
166 
167 	return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
168 				       mode & S_IALLUGO);
169 }
170 
171 /**
172  * tomoyo_path_rmdir - Target for security_path_rmdir().
173  *
174  * @parent: Pointer to "struct path".
175  * @dentry: Pointer to "struct dentry".
176  *
177  * Returns 0 on success, negative value otherwise.
178  */
179 static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
180 {
181 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
182 
183 	return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
184 }
185 
186 /**
187  * tomoyo_path_symlink - Target for security_path_symlink().
188  *
189  * @parent:   Pointer to "struct path".
190  * @dentry:   Pointer to "struct dentry".
191  * @old_name: Symlink's content.
192  *
193  * Returns 0 on success, negative value otherwise.
194  */
195 static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
196 			       const char *old_name)
197 {
198 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
199 
200 	return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
201 }
202 
203 /**
204  * tomoyo_path_mknod - Target for security_path_mknod().
205  *
206  * @parent: Pointer to "struct path".
207  * @dentry: Pointer to "struct dentry".
208  * @mode:   DAC permission mode.
209  * @dev:    Device attributes.
210  *
211  * Returns 0 on success, negative value otherwise.
212  */
213 static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
214 			     umode_t mode, unsigned int dev)
215 {
216 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
217 	int type = TOMOYO_TYPE_CREATE;
218 	const unsigned int perm = mode & S_IALLUGO;
219 
220 	switch (mode & S_IFMT) {
221 	case S_IFCHR:
222 		type = TOMOYO_TYPE_MKCHAR;
223 		break;
224 	case S_IFBLK:
225 		type = TOMOYO_TYPE_MKBLOCK;
226 		break;
227 	default:
228 		goto no_dev;
229 	}
230 	return tomoyo_mkdev_perm(type, &path, perm, dev);
231  no_dev:
232 	switch (mode & S_IFMT) {
233 	case S_IFIFO:
234 		type = TOMOYO_TYPE_MKFIFO;
235 		break;
236 	case S_IFSOCK:
237 		type = TOMOYO_TYPE_MKSOCK;
238 		break;
239 	}
240 	return tomoyo_path_number_perm(type, &path, perm);
241 }
242 
243 /**
244  * tomoyo_path_link - Target for security_path_link().
245  *
246  * @old_dentry: Pointer to "struct dentry".
247  * @new_dir:    Pointer to "struct path".
248  * @new_dentry: Pointer to "struct dentry".
249  *
250  * Returns 0 on success, negative value otherwise.
251  */
252 static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
253 			    struct dentry *new_dentry)
254 {
255 	struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
256 	struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
257 
258 	return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
259 }
260 
261 /**
262  * tomoyo_path_rename - Target for security_path_rename().
263  *
264  * @old_parent: Pointer to "struct path".
265  * @old_dentry: Pointer to "struct dentry".
266  * @new_parent: Pointer to "struct path".
267  * @new_dentry: Pointer to "struct dentry".
268  *
269  * Returns 0 on success, negative value otherwise.
270  */
271 static int tomoyo_path_rename(const struct path *old_parent,
272 			      struct dentry *old_dentry,
273 			      const struct path *new_parent,
274 			      struct dentry *new_dentry)
275 {
276 	struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
277 	struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
278 
279 	return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
280 }
281 
282 /**
283  * tomoyo_file_fcntl - Target for security_file_fcntl().
284  *
285  * @file: Pointer to "struct file".
286  * @cmd:  Command for fcntl().
287  * @arg:  Argument for @cmd.
288  *
289  * Returns 0 on success, negative value otherwise.
290  */
291 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
292 			     unsigned long arg)
293 {
294 	if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
295 		return 0;
296 	return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
297 					    O_WRONLY | (arg & O_APPEND));
298 }
299 
300 /**
301  * tomoyo_file_open - Target for security_file_open().
302  *
303  * @f:    Pointer to "struct file".
304  * @cred: Pointer to "struct cred".
305  *
306  * Returns 0 on success, negative value otherwise.
307  */
308 static int tomoyo_file_open(struct file *f)
309 {
310 	/* Don't check read permission here if called from execve(). */
311 	if (current->in_execve)
312 		return 0;
313 	return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
314 					    f->f_flags);
315 }
316 
317 /**
318  * tomoyo_file_ioctl - Target for security_file_ioctl().
319  *
320  * @file: Pointer to "struct file".
321  * @cmd:  Command for ioctl().
322  * @arg:  Argument for @cmd.
323  *
324  * Returns 0 on success, negative value otherwise.
325  */
326 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
327 			     unsigned long arg)
328 {
329 	return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
330 }
331 
332 /**
333  * tomoyo_path_chmod - Target for security_path_chmod().
334  *
335  * @path: Pointer to "struct path".
336  * @mode: DAC permission mode.
337  *
338  * Returns 0 on success, negative value otherwise.
339  */
340 static int tomoyo_path_chmod(const struct path *path, umode_t mode)
341 {
342 	return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
343 				       mode & S_IALLUGO);
344 }
345 
346 /**
347  * tomoyo_path_chown - Target for security_path_chown().
348  *
349  * @path: Pointer to "struct path".
350  * @uid:  Owner ID.
351  * @gid:  Group ID.
352  *
353  * Returns 0 on success, negative value otherwise.
354  */
355 static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
356 {
357 	int error = 0;
358 
359 	if (uid_valid(uid))
360 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
361 						from_kuid(&init_user_ns, uid));
362 	if (!error && gid_valid(gid))
363 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
364 						from_kgid(&init_user_ns, gid));
365 	return error;
366 }
367 
368 /**
369  * tomoyo_path_chroot - Target for security_path_chroot().
370  *
371  * @path: Pointer to "struct path".
372  *
373  * Returns 0 on success, negative value otherwise.
374  */
375 static int tomoyo_path_chroot(const struct path *path)
376 {
377 	return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
378 }
379 
380 /**
381  * tomoyo_sb_mount - Target for security_sb_mount().
382  *
383  * @dev_name: Name of device file. Maybe NULL.
384  * @path:     Pointer to "struct path".
385  * @type:     Name of filesystem type. Maybe NULL.
386  * @flags:    Mount options.
387  * @data:     Optional data. Maybe NULL.
388  *
389  * Returns 0 on success, negative value otherwise.
390  */
391 static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
392 			   const char *type, unsigned long flags, void *data)
393 {
394 	return tomoyo_mount_permission(dev_name, path, type, flags, data);
395 }
396 
397 /**
398  * tomoyo_sb_umount - Target for security_sb_umount().
399  *
400  * @mnt:   Pointer to "struct vfsmount".
401  * @flags: Unmount options.
402  *
403  * Returns 0 on success, negative value otherwise.
404  */
405 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
406 {
407 	struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
408 
409 	return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
410 }
411 
412 /**
413  * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
414  *
415  * @old_path: Pointer to "struct path".
416  * @new_path: Pointer to "struct path".
417  *
418  * Returns 0 on success, negative value otherwise.
419  */
420 static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
421 {
422 	return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
423 }
424 
425 /**
426  * tomoyo_socket_listen - Check permission for listen().
427  *
428  * @sock:    Pointer to "struct socket".
429  * @backlog: Backlog parameter.
430  *
431  * Returns 0 on success, negative value otherwise.
432  */
433 static int tomoyo_socket_listen(struct socket *sock, int backlog)
434 {
435 	return tomoyo_socket_listen_permission(sock);
436 }
437 
438 /**
439  * tomoyo_socket_connect - Check permission for connect().
440  *
441  * @sock:     Pointer to "struct socket".
442  * @addr:     Pointer to "struct sockaddr".
443  * @addr_len: Size of @addr.
444  *
445  * Returns 0 on success, negative value otherwise.
446  */
447 static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
448 				 int addr_len)
449 {
450 	return tomoyo_socket_connect_permission(sock, addr, addr_len);
451 }
452 
453 /**
454  * tomoyo_socket_bind - Check permission for bind().
455  *
456  * @sock:     Pointer to "struct socket".
457  * @addr:     Pointer to "struct sockaddr".
458  * @addr_len: Size of @addr.
459  *
460  * Returns 0 on success, negative value otherwise.
461  */
462 static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
463 			      int addr_len)
464 {
465 	return tomoyo_socket_bind_permission(sock, addr, addr_len);
466 }
467 
468 /**
469  * tomoyo_socket_sendmsg - Check permission for sendmsg().
470  *
471  * @sock: Pointer to "struct socket".
472  * @msg:  Pointer to "struct msghdr".
473  * @size: Size of message.
474  *
475  * Returns 0 on success, negative value otherwise.
476  */
477 static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
478 				 int size)
479 {
480 	return tomoyo_socket_sendmsg_permission(sock, msg, size);
481 }
482 
483 struct lsm_blob_sizes tomoyo_blob_sizes __lsm_ro_after_init = {
484 	.lbs_task = sizeof(struct tomoyo_task),
485 };
486 
487 /**
488  * tomoyo_task_alloc - Target for security_task_alloc().
489  *
490  * @task:  Pointer to "struct task_struct".
491  * @flags: clone() flags.
492  *
493  * Returns 0.
494  */
495 static int tomoyo_task_alloc(struct task_struct *task,
496 			     unsigned long clone_flags)
497 {
498 	struct tomoyo_task *old = tomoyo_task(current);
499 	struct tomoyo_task *new = tomoyo_task(task);
500 
501 	new->domain_info = old->domain_info;
502 	atomic_inc(&new->domain_info->users);
503 	new->old_domain_info = NULL;
504 	return 0;
505 }
506 
507 /**
508  * tomoyo_task_free - Target for security_task_free().
509  *
510  * @task: Pointer to "struct task_struct".
511  */
512 static void tomoyo_task_free(struct task_struct *task)
513 {
514 	struct tomoyo_task *s = tomoyo_task(task);
515 
516 	if (s->domain_info) {
517 		atomic_dec(&s->domain_info->users);
518 		s->domain_info = NULL;
519 	}
520 	if (s->old_domain_info) {
521 		atomic_dec(&s->old_domain_info->users);
522 		s->old_domain_info = NULL;
523 	}
524 }
525 
526 /*
527  * tomoyo_security_ops is a "struct security_operations" which is used for
528  * registering TOMOYO.
529  */
530 static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
531 	LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
532 	LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
533 	LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
534 	LSM_HOOK_INIT(task_free, tomoyo_task_free),
535 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
536 	LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
537 #endif
538 	LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
539 	LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
540 	LSM_HOOK_INIT(file_open, tomoyo_file_open),
541 	LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
542 	LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
543 	LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
544 	LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
545 	LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
546 	LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
547 	LSM_HOOK_INIT(path_link, tomoyo_path_link),
548 	LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
549 	LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
550 	LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
551 	LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
552 	LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
553 	LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
554 	LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
555 	LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
556 	LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
557 	LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
558 	LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
559 	LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
560 	LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
561 };
562 
563 /* Lock for GC. */
564 DEFINE_SRCU(tomoyo_ss);
565 
566 int tomoyo_enabled __lsm_ro_after_init = 1;
567 
568 /**
569  * tomoyo_init - Register TOMOYO Linux as a LSM module.
570  *
571  * Returns 0.
572  */
573 static int __init tomoyo_init(void)
574 {
575 	struct tomoyo_task *s = tomoyo_task(current);
576 
577 	/* register ourselves with the security framework */
578 	security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
579 	pr_info("TOMOYO Linux initialized\n");
580 	s->domain_info = &tomoyo_kernel_domain;
581 	atomic_inc(&tomoyo_kernel_domain.users);
582 	s->old_domain_info = NULL;
583 	tomoyo_mm_init();
584 
585 	return 0;
586 }
587 
588 DEFINE_LSM(tomoyo) = {
589 	.name = "tomoyo",
590 	.enabled = &tomoyo_enabled,
591 	.flags = LSM_FLAG_LEGACY_MAJOR,
592 	.blobs = &tomoyo_blob_sizes,
593 	.init = tomoyo_init,
594 };
595