xref: /openbmc/linux/security/tomoyo/tomoyo.c (revision fa0dadde) 
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_creds_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  * @path: Pointer to "struct path".
117  *
118  * Returns 0 on success, negative value otherwise.
119  */
120 static int tomoyo_inode_getattr(const struct path *path)
121 {
122 	return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, path, NULL);
123 }
124 
125 /**
126  * tomoyo_path_truncate - Target for security_path_truncate().
127  *
128  * @path: Pointer to "struct path".
129  *
130  * Returns 0 on success, negative value otherwise.
131  */
132 static int tomoyo_path_truncate(const struct path *path)
133 {
134 	return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
135 }
136 
137 /**
138  * tomoyo_file_truncate - Target for security_file_truncate().
139  *
140  * @file: Pointer to "struct file".
141  *
142  * Returns 0 on success, negative value otherwise.
143  */
144 static int tomoyo_file_truncate(struct file *file)
145 {
146 	return tomoyo_path_truncate(&file->f_path);
147 }
148 
149 /**
150  * tomoyo_path_unlink - Target for security_path_unlink().
151  *
152  * @parent: Pointer to "struct path".
153  * @dentry: Pointer to "struct dentry".
154  *
155  * Returns 0 on success, negative value otherwise.
156  */
157 static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
158 {
159 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
160 
161 	return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
162 }
163 
164 /**
165  * tomoyo_path_mkdir - Target for security_path_mkdir().
166  *
167  * @parent: Pointer to "struct path".
168  * @dentry: Pointer to "struct dentry".
169  * @mode:   DAC permission mode.
170  *
171  * Returns 0 on success, negative value otherwise.
172  */
173 static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
174 			     umode_t mode)
175 {
176 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
177 
178 	return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
179 				       mode & S_IALLUGO);
180 }
181 
182 /**
183  * tomoyo_path_rmdir - Target for security_path_rmdir().
184  *
185  * @parent: Pointer to "struct path".
186  * @dentry: Pointer to "struct dentry".
187  *
188  * Returns 0 on success, negative value otherwise.
189  */
190 static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
191 {
192 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
193 
194 	return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
195 }
196 
197 /**
198  * tomoyo_path_symlink - Target for security_path_symlink().
199  *
200  * @parent:   Pointer to "struct path".
201  * @dentry:   Pointer to "struct dentry".
202  * @old_name: Symlink's content.
203  *
204  * Returns 0 on success, negative value otherwise.
205  */
206 static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
207 			       const char *old_name)
208 {
209 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
210 
211 	return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
212 }
213 
214 /**
215  * tomoyo_path_mknod - Target for security_path_mknod().
216  *
217  * @parent: Pointer to "struct path".
218  * @dentry: Pointer to "struct dentry".
219  * @mode:   DAC permission mode.
220  * @dev:    Device attributes.
221  *
222  * Returns 0 on success, negative value otherwise.
223  */
224 static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
225 			     umode_t mode, unsigned int dev)
226 {
227 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
228 	int type = TOMOYO_TYPE_CREATE;
229 	const unsigned int perm = mode & S_IALLUGO;
230 
231 	switch (mode & S_IFMT) {
232 	case S_IFCHR:
233 		type = TOMOYO_TYPE_MKCHAR;
234 		break;
235 	case S_IFBLK:
236 		type = TOMOYO_TYPE_MKBLOCK;
237 		break;
238 	default:
239 		goto no_dev;
240 	}
241 	return tomoyo_mkdev_perm(type, &path, perm, dev);
242  no_dev:
243 	switch (mode & S_IFMT) {
244 	case S_IFIFO:
245 		type = TOMOYO_TYPE_MKFIFO;
246 		break;
247 	case S_IFSOCK:
248 		type = TOMOYO_TYPE_MKSOCK;
249 		break;
250 	}
251 	return tomoyo_path_number_perm(type, &path, perm);
252 }
253 
254 /**
255  * tomoyo_path_link - Target for security_path_link().
256  *
257  * @old_dentry: Pointer to "struct dentry".
258  * @new_dir:    Pointer to "struct path".
259  * @new_dentry: Pointer to "struct dentry".
260  *
261  * Returns 0 on success, negative value otherwise.
262  */
263 static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
264 			    struct dentry *new_dentry)
265 {
266 	struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
267 	struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
268 
269 	return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
270 }
271 
272 /**
273  * tomoyo_path_rename - Target for security_path_rename().
274  *
275  * @old_parent: Pointer to "struct path".
276  * @old_dentry: Pointer to "struct dentry".
277  * @new_parent: Pointer to "struct path".
278  * @new_dentry: Pointer to "struct dentry".
279  * @flags: Rename options.
280  *
281  * Returns 0 on success, negative value otherwise.
282  */
283 static int tomoyo_path_rename(const struct path *old_parent,
284 			      struct dentry *old_dentry,
285 			      const struct path *new_parent,
286 			      struct dentry *new_dentry,
287 			      const unsigned int flags)
288 {
289 	struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
290 	struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
291 
292 	if (flags & RENAME_EXCHANGE) {
293 		const int err = tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path2,
294 				&path1);
295 
296 		if (err)
297 			return err;
298 	}
299 	return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
300 }
301 
302 /**
303  * tomoyo_file_fcntl - Target for security_file_fcntl().
304  *
305  * @file: Pointer to "struct file".
306  * @cmd:  Command for fcntl().
307  * @arg:  Argument for @cmd.
308  *
309  * Returns 0 on success, negative value otherwise.
310  */
311 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
312 			     unsigned long arg)
313 {
314 	if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
315 		return 0;
316 	return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
317 					    O_WRONLY | (arg & O_APPEND));
318 }
319 
320 /**
321  * tomoyo_file_open - Target for security_file_open().
322  *
323  * @f: Pointer to "struct file".
324  *
325  * Returns 0 on success, negative value otherwise.
326  */
327 static int tomoyo_file_open(struct file *f)
328 {
329 	/* Don't check read permission here if called from execve(). */
330 	if (current->in_execve)
331 		return 0;
332 	return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
333 					    f->f_flags);
334 }
335 
336 /**
337  * tomoyo_file_ioctl - Target for security_file_ioctl().
338  *
339  * @file: Pointer to "struct file".
340  * @cmd:  Command for ioctl().
341  * @arg:  Argument for @cmd.
342  *
343  * Returns 0 on success, negative value otherwise.
344  */
345 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
346 			     unsigned long arg)
347 {
348 	return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
349 }
350 
351 /**
352  * tomoyo_path_chmod - Target for security_path_chmod().
353  *
354  * @path: Pointer to "struct path".
355  * @mode: DAC permission mode.
356  *
357  * Returns 0 on success, negative value otherwise.
358  */
359 static int tomoyo_path_chmod(const struct path *path, umode_t mode)
360 {
361 	return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
362 				       mode & S_IALLUGO);
363 }
364 
365 /**
366  * tomoyo_path_chown - Target for security_path_chown().
367  *
368  * @path: Pointer to "struct path".
369  * @uid:  Owner ID.
370  * @gid:  Group ID.
371  *
372  * Returns 0 on success, negative value otherwise.
373  */
374 static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
375 {
376 	int error = 0;
377 
378 	if (uid_valid(uid))
379 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
380 						from_kuid(&init_user_ns, uid));
381 	if (!error && gid_valid(gid))
382 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
383 						from_kgid(&init_user_ns, gid));
384 	return error;
385 }
386 
387 /**
388  * tomoyo_path_chroot - Target for security_path_chroot().
389  *
390  * @path: Pointer to "struct path".
391  *
392  * Returns 0 on success, negative value otherwise.
393  */
394 static int tomoyo_path_chroot(const struct path *path)
395 {
396 	return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
397 }
398 
399 /**
400  * tomoyo_sb_mount - Target for security_sb_mount().
401  *
402  * @dev_name: Name of device file. Maybe NULL.
403  * @path:     Pointer to "struct path".
404  * @type:     Name of filesystem type. Maybe NULL.
405  * @flags:    Mount options.
406  * @data:     Optional data. Maybe NULL.
407  *
408  * Returns 0 on success, negative value otherwise.
409  */
410 static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
411 			   const char *type, unsigned long flags, void *data)
412 {
413 	return tomoyo_mount_permission(dev_name, path, type, flags, data);
414 }
415 
416 /**
417  * tomoyo_sb_umount - Target for security_sb_umount().
418  *
419  * @mnt:   Pointer to "struct vfsmount".
420  * @flags: Unmount options.
421  *
422  * Returns 0 on success, negative value otherwise.
423  */
424 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
425 {
426 	struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
427 
428 	return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
429 }
430 
431 /**
432  * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
433  *
434  * @old_path: Pointer to "struct path".
435  * @new_path: Pointer to "struct path".
436  *
437  * Returns 0 on success, negative value otherwise.
438  */
439 static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
440 {
441 	return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
442 }
443 
444 /**
445  * tomoyo_socket_listen - Check permission for listen().
446  *
447  * @sock:    Pointer to "struct socket".
448  * @backlog: Backlog parameter.
449  *
450  * Returns 0 on success, negative value otherwise.
451  */
452 static int tomoyo_socket_listen(struct socket *sock, int backlog)
453 {
454 	return tomoyo_socket_listen_permission(sock);
455 }
456 
457 /**
458  * tomoyo_socket_connect - Check permission for connect().
459  *
460  * @sock:     Pointer to "struct socket".
461  * @addr:     Pointer to "struct sockaddr".
462  * @addr_len: Size of @addr.
463  *
464  * Returns 0 on success, negative value otherwise.
465  */
466 static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
467 				 int addr_len)
468 {
469 	return tomoyo_socket_connect_permission(sock, addr, addr_len);
470 }
471 
472 /**
473  * tomoyo_socket_bind - Check permission for bind().
474  *
475  * @sock:     Pointer to "struct socket".
476  * @addr:     Pointer to "struct sockaddr".
477  * @addr_len: Size of @addr.
478  *
479  * Returns 0 on success, negative value otherwise.
480  */
481 static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
482 			      int addr_len)
483 {
484 	return tomoyo_socket_bind_permission(sock, addr, addr_len);
485 }
486 
487 /**
488  * tomoyo_socket_sendmsg - Check permission for sendmsg().
489  *
490  * @sock: Pointer to "struct socket".
491  * @msg:  Pointer to "struct msghdr".
492  * @size: Size of message.
493  *
494  * Returns 0 on success, negative value otherwise.
495  */
496 static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
497 				 int size)
498 {
499 	return tomoyo_socket_sendmsg_permission(sock, msg, size);
500 }
501 
502 struct lsm_blob_sizes tomoyo_blob_sizes __ro_after_init = {
503 	.lbs_task = sizeof(struct tomoyo_task),
504 };
505 
506 /**
507  * tomoyo_task_alloc - Target for security_task_alloc().
508  *
509  * @task:        Pointer to "struct task_struct".
510  * @clone_flags: clone() flags.
511  *
512  * Returns 0.
513  */
514 static int tomoyo_task_alloc(struct task_struct *task,
515 			     unsigned long clone_flags)
516 {
517 	struct tomoyo_task *old = tomoyo_task(current);
518 	struct tomoyo_task *new = tomoyo_task(task);
519 
520 	new->domain_info = old->domain_info;
521 	atomic_inc(&new->domain_info->users);
522 	new->old_domain_info = NULL;
523 	return 0;
524 }
525 
526 /**
527  * tomoyo_task_free - Target for security_task_free().
528  *
529  * @task: Pointer to "struct task_struct".
530  */
531 static void tomoyo_task_free(struct task_struct *task)
532 {
533 	struct tomoyo_task *s = tomoyo_task(task);
534 
535 	if (s->domain_info) {
536 		atomic_dec(&s->domain_info->users);
537 		s->domain_info = NULL;
538 	}
539 	if (s->old_domain_info) {
540 		atomic_dec(&s->old_domain_info->users);
541 		s->old_domain_info = NULL;
542 	}
543 }
544 
545 /*
546  * tomoyo_security_ops is a "struct security_operations" which is used for
547  * registering TOMOYO.
548  */
549 static struct security_hook_list tomoyo_hooks[] __ro_after_init = {
550 	LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
551 	LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
552 	LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
553 	LSM_HOOK_INIT(task_free, tomoyo_task_free),
554 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
555 	LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
556 #endif
557 	LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
558 	LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
559 	LSM_HOOK_INIT(file_open, tomoyo_file_open),
560 	LSM_HOOK_INIT(file_truncate, tomoyo_file_truncate),
561 	LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
562 	LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
563 	LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
564 	LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
565 	LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
566 	LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
567 	LSM_HOOK_INIT(path_link, tomoyo_path_link),
568 	LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
569 	LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
570 	LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
571 	LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
572 	LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
573 	LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
574 	LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
575 	LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
576 	LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
577 	LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
578 	LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
579 	LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
580 	LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
581 };
582 
583 /* Lock for GC. */
584 DEFINE_SRCU(tomoyo_ss);
585 
586 int tomoyo_enabled __ro_after_init = 1;
587 
588 /**
589  * tomoyo_init - Register TOMOYO Linux as a LSM module.
590  *
591  * Returns 0.
592  */
593 static int __init tomoyo_init(void)
594 {
595 	struct tomoyo_task *s = tomoyo_task(current);
596 
597 	/* register ourselves with the security framework */
598 	security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
599 	pr_info("TOMOYO Linux initialized\n");
600 	s->domain_info = &tomoyo_kernel_domain;
601 	atomic_inc(&tomoyo_kernel_domain.users);
602 	s->old_domain_info = NULL;
603 	tomoyo_mm_init();
604 
605 	return 0;
606 }
607 
608 DEFINE_LSM(tomoyo) = {
609 	.name = "tomoyo",
610 	.enabled = &tomoyo_enabled,
611 	.flags = LSM_FLAG_LEGACY_MAJOR,
612 	.blobs = &tomoyo_blob_sizes,
613 	.init = tomoyo_init,
614 };
615