xref: /openbmc/linux/security/tomoyo/tomoyo.c (revision ccc319dc) 
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_path_unlink - Target for security_path_unlink().
139  *
140  * @parent: Pointer to "struct path".
141  * @dentry: Pointer to "struct dentry".
142  *
143  * Returns 0 on success, negative value otherwise.
144  */
145 static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
146 {
147 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
148 
149 	return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
150 }
151 
152 /**
153  * tomoyo_path_mkdir - Target for security_path_mkdir().
154  *
155  * @parent: Pointer to "struct path".
156  * @dentry: Pointer to "struct dentry".
157  * @mode:   DAC permission mode.
158  *
159  * Returns 0 on success, negative value otherwise.
160  */
161 static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
162 			     umode_t mode)
163 {
164 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
165 
166 	return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
167 				       mode & S_IALLUGO);
168 }
169 
170 /**
171  * tomoyo_path_rmdir - Target for security_path_rmdir().
172  *
173  * @parent: Pointer to "struct path".
174  * @dentry: Pointer to "struct dentry".
175  *
176  * Returns 0 on success, negative value otherwise.
177  */
178 static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
179 {
180 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
181 
182 	return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
183 }
184 
185 /**
186  * tomoyo_path_symlink - Target for security_path_symlink().
187  *
188  * @parent:   Pointer to "struct path".
189  * @dentry:   Pointer to "struct dentry".
190  * @old_name: Symlink's content.
191  *
192  * Returns 0 on success, negative value otherwise.
193  */
194 static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
195 			       const char *old_name)
196 {
197 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
198 
199 	return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
200 }
201 
202 /**
203  * tomoyo_path_mknod - Target for security_path_mknod().
204  *
205  * @parent: Pointer to "struct path".
206  * @dentry: Pointer to "struct dentry".
207  * @mode:   DAC permission mode.
208  * @dev:    Device attributes.
209  *
210  * Returns 0 on success, negative value otherwise.
211  */
212 static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
213 			     umode_t mode, unsigned int dev)
214 {
215 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
216 	int type = TOMOYO_TYPE_CREATE;
217 	const unsigned int perm = mode & S_IALLUGO;
218 
219 	switch (mode & S_IFMT) {
220 	case S_IFCHR:
221 		type = TOMOYO_TYPE_MKCHAR;
222 		break;
223 	case S_IFBLK:
224 		type = TOMOYO_TYPE_MKBLOCK;
225 		break;
226 	default:
227 		goto no_dev;
228 	}
229 	return tomoyo_mkdev_perm(type, &path, perm, dev);
230  no_dev:
231 	switch (mode & S_IFMT) {
232 	case S_IFIFO:
233 		type = TOMOYO_TYPE_MKFIFO;
234 		break;
235 	case S_IFSOCK:
236 		type = TOMOYO_TYPE_MKSOCK;
237 		break;
238 	}
239 	return tomoyo_path_number_perm(type, &path, perm);
240 }
241 
242 /**
243  * tomoyo_path_link - Target for security_path_link().
244  *
245  * @old_dentry: Pointer to "struct dentry".
246  * @new_dir:    Pointer to "struct path".
247  * @new_dentry: Pointer to "struct dentry".
248  *
249  * Returns 0 on success, negative value otherwise.
250  */
251 static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
252 			    struct dentry *new_dentry)
253 {
254 	struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
255 	struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
256 
257 	return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
258 }
259 
260 /**
261  * tomoyo_path_rename - Target for security_path_rename().
262  *
263  * @old_parent: Pointer to "struct path".
264  * @old_dentry: Pointer to "struct dentry".
265  * @new_parent: Pointer to "struct path".
266  * @new_dentry: Pointer to "struct dentry".
267  * @flags: Rename options.
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 			      const unsigned int flags)
276 {
277 	struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
278 	struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
279 
280 	if (flags & RENAME_EXCHANGE) {
281 		const int err = tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path2,
282 				&path1);
283 
284 		if (err)
285 			return err;
286 	}
287 	return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
288 }
289 
290 /**
291  * tomoyo_file_fcntl - Target for security_file_fcntl().
292  *
293  * @file: Pointer to "struct file".
294  * @cmd:  Command for fcntl().
295  * @arg:  Argument for @cmd.
296  *
297  * Returns 0 on success, negative value otherwise.
298  */
299 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
300 			     unsigned long arg)
301 {
302 	if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
303 		return 0;
304 	return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
305 					    O_WRONLY | (arg & O_APPEND));
306 }
307 
308 /**
309  * tomoyo_file_open - Target for security_file_open().
310  *
311  * @f: Pointer to "struct file".
312  *
313  * Returns 0 on success, negative value otherwise.
314  */
315 static int tomoyo_file_open(struct file *f)
316 {
317 	/* Don't check read permission here if called from execve(). */
318 	if (current->in_execve)
319 		return 0;
320 	return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
321 					    f->f_flags);
322 }
323 
324 /**
325  * tomoyo_file_ioctl - Target for security_file_ioctl().
326  *
327  * @file: Pointer to "struct file".
328  * @cmd:  Command for ioctl().
329  * @arg:  Argument for @cmd.
330  *
331  * Returns 0 on success, negative value otherwise.
332  */
333 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
334 			     unsigned long arg)
335 {
336 	return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
337 }
338 
339 /**
340  * tomoyo_path_chmod - Target for security_path_chmod().
341  *
342  * @path: Pointer to "struct path".
343  * @mode: DAC permission mode.
344  *
345  * Returns 0 on success, negative value otherwise.
346  */
347 static int tomoyo_path_chmod(const struct path *path, umode_t mode)
348 {
349 	return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
350 				       mode & S_IALLUGO);
351 }
352 
353 /**
354  * tomoyo_path_chown - Target for security_path_chown().
355  *
356  * @path: Pointer to "struct path".
357  * @uid:  Owner ID.
358  * @gid:  Group ID.
359  *
360  * Returns 0 on success, negative value otherwise.
361  */
362 static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
363 {
364 	int error = 0;
365 
366 	if (uid_valid(uid))
367 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
368 						from_kuid(&init_user_ns, uid));
369 	if (!error && gid_valid(gid))
370 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
371 						from_kgid(&init_user_ns, gid));
372 	return error;
373 }
374 
375 /**
376  * tomoyo_path_chroot - Target for security_path_chroot().
377  *
378  * @path: Pointer to "struct path".
379  *
380  * Returns 0 on success, negative value otherwise.
381  */
382 static int tomoyo_path_chroot(const struct path *path)
383 {
384 	return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
385 }
386 
387 /**
388  * tomoyo_sb_mount - Target for security_sb_mount().
389  *
390  * @dev_name: Name of device file. Maybe NULL.
391  * @path:     Pointer to "struct path".
392  * @type:     Name of filesystem type. Maybe NULL.
393  * @flags:    Mount options.
394  * @data:     Optional data. Maybe NULL.
395  *
396  * Returns 0 on success, negative value otherwise.
397  */
398 static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
399 			   const char *type, unsigned long flags, void *data)
400 {
401 	return tomoyo_mount_permission(dev_name, path, type, flags, data);
402 }
403 
404 /**
405  * tomoyo_sb_umount - Target for security_sb_umount().
406  *
407  * @mnt:   Pointer to "struct vfsmount".
408  * @flags: Unmount options.
409  *
410  * Returns 0 on success, negative value otherwise.
411  */
412 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
413 {
414 	struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
415 
416 	return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
417 }
418 
419 /**
420  * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
421  *
422  * @old_path: Pointer to "struct path".
423  * @new_path: Pointer to "struct path".
424  *
425  * Returns 0 on success, negative value otherwise.
426  */
427 static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
428 {
429 	return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
430 }
431 
432 /**
433  * tomoyo_socket_listen - Check permission for listen().
434  *
435  * @sock:    Pointer to "struct socket".
436  * @backlog: Backlog parameter.
437  *
438  * Returns 0 on success, negative value otherwise.
439  */
440 static int tomoyo_socket_listen(struct socket *sock, int backlog)
441 {
442 	return tomoyo_socket_listen_permission(sock);
443 }
444 
445 /**
446  * tomoyo_socket_connect - Check permission for connect().
447  *
448  * @sock:     Pointer to "struct socket".
449  * @addr:     Pointer to "struct sockaddr".
450  * @addr_len: Size of @addr.
451  *
452  * Returns 0 on success, negative value otherwise.
453  */
454 static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
455 				 int addr_len)
456 {
457 	return tomoyo_socket_connect_permission(sock, addr, addr_len);
458 }
459 
460 /**
461  * tomoyo_socket_bind - Check permission for bind().
462  *
463  * @sock:     Pointer to "struct socket".
464  * @addr:     Pointer to "struct sockaddr".
465  * @addr_len: Size of @addr.
466  *
467  * Returns 0 on success, negative value otherwise.
468  */
469 static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
470 			      int addr_len)
471 {
472 	return tomoyo_socket_bind_permission(sock, addr, addr_len);
473 }
474 
475 /**
476  * tomoyo_socket_sendmsg - Check permission for sendmsg().
477  *
478  * @sock: Pointer to "struct socket".
479  * @msg:  Pointer to "struct msghdr".
480  * @size: Size of message.
481  *
482  * Returns 0 on success, negative value otherwise.
483  */
484 static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
485 				 int size)
486 {
487 	return tomoyo_socket_sendmsg_permission(sock, msg, size);
488 }
489 
490 struct lsm_blob_sizes tomoyo_blob_sizes __lsm_ro_after_init = {
491 	.lbs_task = sizeof(struct tomoyo_task),
492 };
493 
494 /**
495  * tomoyo_task_alloc - Target for security_task_alloc().
496  *
497  * @task:        Pointer to "struct task_struct".
498  * @clone_flags: clone() flags.
499  *
500  * Returns 0.
501  */
502 static int tomoyo_task_alloc(struct task_struct *task,
503 			     unsigned long clone_flags)
504 {
505 	struct tomoyo_task *old = tomoyo_task(current);
506 	struct tomoyo_task *new = tomoyo_task(task);
507 
508 	new->domain_info = old->domain_info;
509 	atomic_inc(&new->domain_info->users);
510 	new->old_domain_info = NULL;
511 	return 0;
512 }
513 
514 /**
515  * tomoyo_task_free - Target for security_task_free().
516  *
517  * @task: Pointer to "struct task_struct".
518  */
519 static void tomoyo_task_free(struct task_struct *task)
520 {
521 	struct tomoyo_task *s = tomoyo_task(task);
522 
523 	if (s->domain_info) {
524 		atomic_dec(&s->domain_info->users);
525 		s->domain_info = NULL;
526 	}
527 	if (s->old_domain_info) {
528 		atomic_dec(&s->old_domain_info->users);
529 		s->old_domain_info = NULL;
530 	}
531 }
532 
533 /*
534  * tomoyo_security_ops is a "struct security_operations" which is used for
535  * registering TOMOYO.
536  */
537 static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
538 	LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
539 	LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
540 	LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
541 	LSM_HOOK_INIT(task_free, tomoyo_task_free),
542 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
543 	LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
544 #endif
545 	LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
546 	LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
547 	LSM_HOOK_INIT(file_open, tomoyo_file_open),
548 	LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
549 	LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
550 	LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
551 	LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
552 	LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
553 	LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
554 	LSM_HOOK_INIT(path_link, tomoyo_path_link),
555 	LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
556 	LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
557 	LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
558 	LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
559 	LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
560 	LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
561 	LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
562 	LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
563 	LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
564 	LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
565 	LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
566 	LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
567 	LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
568 };
569 
570 /* Lock for GC. */
571 DEFINE_SRCU(tomoyo_ss);
572 
573 int tomoyo_enabled __lsm_ro_after_init = 1;
574 
575 /**
576  * tomoyo_init - Register TOMOYO Linux as a LSM module.
577  *
578  * Returns 0.
579  */
580 static int __init tomoyo_init(void)
581 {
582 	struct tomoyo_task *s = tomoyo_task(current);
583 
584 	/* register ourselves with the security framework */
585 	security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
586 	pr_info("TOMOYO Linux initialized\n");
587 	s->domain_info = &tomoyo_kernel_domain;
588 	atomic_inc(&tomoyo_kernel_domain.users);
589 	s->old_domain_info = NULL;
590 	tomoyo_mm_init();
591 
592 	return 0;
593 }
594 
595 DEFINE_LSM(tomoyo) = {
596 	.name = "tomoyo",
597 	.enabled = &tomoyo_enabled,
598 	.flags = LSM_FLAG_LEGACY_MAJOR,
599 	.blobs = &tomoyo_blob_sizes,
600 	.init = tomoyo_init,
601 };
602