xref: /openbmc/linux/security/tomoyo/tomoyo.c (revision a36954f5)
1 /*
2  * security/tomoyo/tomoyo.c
3  *
4  * Copyright (C) 2005-2011  NTT DATA CORPORATION
5  */
6 
7 #include <linux/lsm_hooks.h>
8 #include "common.h"
9 
10 /**
11  * tomoyo_cred_alloc_blank - Target for security_cred_alloc_blank().
12  *
13  * @new: Pointer to "struct cred".
14  * @gfp: Memory allocation flags.
15  *
16  * Returns 0.
17  */
18 static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
19 {
20 	new->security = NULL;
21 	return 0;
22 }
23 
24 /**
25  * tomoyo_cred_prepare - Target for security_prepare_creds().
26  *
27  * @new: Pointer to "struct cred".
28  * @old: Pointer to "struct cred".
29  * @gfp: Memory allocation flags.
30  *
31  * Returns 0.
32  */
33 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
34 			       gfp_t gfp)
35 {
36 	struct tomoyo_domain_info *domain = old->security;
37 	new->security = domain;
38 	if (domain)
39 		atomic_inc(&domain->users);
40 	return 0;
41 }
42 
43 /**
44  * tomoyo_cred_transfer - Target for security_transfer_creds().
45  *
46  * @new: Pointer to "struct cred".
47  * @old: Pointer to "struct cred".
48  */
49 static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
50 {
51 	tomoyo_cred_prepare(new, old, 0);
52 }
53 
54 /**
55  * tomoyo_cred_free - Target for security_cred_free().
56  *
57  * @cred: Pointer to "struct cred".
58  */
59 static void tomoyo_cred_free(struct cred *cred)
60 {
61 	struct tomoyo_domain_info *domain = cred->security;
62 	if (domain)
63 		atomic_dec(&domain->users);
64 }
65 
66 /**
67  * tomoyo_bprm_set_creds - Target for security_bprm_set_creds().
68  *
69  * @bprm: Pointer to "struct linux_binprm".
70  *
71  * Returns 0 on success, negative value otherwise.
72  */
73 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
74 {
75 	/*
76 	 * Do only if this function is called for the first time of an execve
77 	 * operation.
78 	 */
79 	if (bprm->cred_prepared)
80 		return 0;
81 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
82 	/*
83 	 * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
84 	 * for the first time.
85 	 */
86 	if (!tomoyo_policy_loaded)
87 		tomoyo_load_policy(bprm->filename);
88 #endif
89 	/*
90 	 * Release reference to "struct tomoyo_domain_info" stored inside
91 	 * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
92 	 * stored inside "bprm->cred->security" will be acquired later inside
93 	 * tomoyo_find_next_domain().
94 	 */
95 	atomic_dec(&((struct tomoyo_domain_info *)
96 		     bprm->cred->security)->users);
97 	/*
98 	 * Tell tomoyo_bprm_check_security() is called for the first time of an
99 	 * execve operation.
100 	 */
101 	bprm->cred->security = NULL;
102 	return 0;
103 }
104 
105 /**
106  * tomoyo_bprm_check_security - Target for security_bprm_check().
107  *
108  * @bprm: Pointer to "struct linux_binprm".
109  *
110  * Returns 0 on success, negative value otherwise.
111  */
112 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
113 {
114 	struct tomoyo_domain_info *domain = bprm->cred->security;
115 
116 	/*
117 	 * Execute permission is checked against pathname passed to do_execve()
118 	 * using current domain.
119 	 */
120 	if (!domain) {
121 		const int idx = tomoyo_read_lock();
122 		const int err = tomoyo_find_next_domain(bprm);
123 		tomoyo_read_unlock(idx);
124 		return err;
125 	}
126 	/*
127 	 * Read permission is checked against interpreters using next domain.
128 	 */
129 	return tomoyo_check_open_permission(domain, &bprm->file->f_path,
130 					    O_RDONLY);
131 }
132 
133 /**
134  * tomoyo_inode_getattr - Target for security_inode_getattr().
135  *
136  * @mnt:    Pointer to "struct vfsmount".
137  * @dentry: Pointer to "struct dentry".
138  *
139  * Returns 0 on success, negative value otherwise.
140  */
141 static int tomoyo_inode_getattr(const struct path *path)
142 {
143 	return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, path, NULL);
144 }
145 
146 /**
147  * tomoyo_path_truncate - Target for security_path_truncate().
148  *
149  * @path: Pointer to "struct path".
150  *
151  * Returns 0 on success, negative value otherwise.
152  */
153 static int tomoyo_path_truncate(const struct path *path)
154 {
155 	return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
156 }
157 
158 /**
159  * tomoyo_path_unlink - Target for security_path_unlink().
160  *
161  * @parent: Pointer to "struct path".
162  * @dentry: Pointer to "struct dentry".
163  *
164  * Returns 0 on success, negative value otherwise.
165  */
166 static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
167 {
168 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
169 	return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
170 }
171 
172 /**
173  * tomoyo_path_mkdir - Target for security_path_mkdir().
174  *
175  * @parent: Pointer to "struct path".
176  * @dentry: Pointer to "struct dentry".
177  * @mode:   DAC permission mode.
178  *
179  * Returns 0 on success, negative value otherwise.
180  */
181 static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
182 			     umode_t mode)
183 {
184 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
185 	return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
186 				       mode & S_IALLUGO);
187 }
188 
189 /**
190  * tomoyo_path_rmdir - Target for security_path_rmdir().
191  *
192  * @parent: Pointer to "struct path".
193  * @dentry: Pointer to "struct dentry".
194  *
195  * Returns 0 on success, negative value otherwise.
196  */
197 static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
198 {
199 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
200 	return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
201 }
202 
203 /**
204  * tomoyo_path_symlink - Target for security_path_symlink().
205  *
206  * @parent:   Pointer to "struct path".
207  * @dentry:   Pointer to "struct dentry".
208  * @old_name: Symlink's content.
209  *
210  * Returns 0 on success, negative value otherwise.
211  */
212 static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
213 			       const char *old_name)
214 {
215 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
216 	return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
217 }
218 
219 /**
220  * tomoyo_path_mknod - Target for security_path_mknod().
221  *
222  * @parent: Pointer to "struct path".
223  * @dentry: Pointer to "struct dentry".
224  * @mode:   DAC permission mode.
225  * @dev:    Device attributes.
226  *
227  * Returns 0 on success, negative value otherwise.
228  */
229 static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
230 			     umode_t mode, unsigned int dev)
231 {
232 	struct path path = { .mnt = parent->mnt, .dentry = dentry };
233 	int type = TOMOYO_TYPE_CREATE;
234 	const unsigned int perm = mode & S_IALLUGO;
235 
236 	switch (mode & S_IFMT) {
237 	case S_IFCHR:
238 		type = TOMOYO_TYPE_MKCHAR;
239 		break;
240 	case S_IFBLK:
241 		type = TOMOYO_TYPE_MKBLOCK;
242 		break;
243 	default:
244 		goto no_dev;
245 	}
246 	return tomoyo_mkdev_perm(type, &path, perm, dev);
247  no_dev:
248 	switch (mode & S_IFMT) {
249 	case S_IFIFO:
250 		type = TOMOYO_TYPE_MKFIFO;
251 		break;
252 	case S_IFSOCK:
253 		type = TOMOYO_TYPE_MKSOCK;
254 		break;
255 	}
256 	return tomoyo_path_number_perm(type, &path, perm);
257 }
258 
259 /**
260  * tomoyo_path_link - Target for security_path_link().
261  *
262  * @old_dentry: Pointer to "struct dentry".
263  * @new_dir:    Pointer to "struct path".
264  * @new_dentry: Pointer to "struct dentry".
265  *
266  * Returns 0 on success, negative value otherwise.
267  */
268 static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
269 			    struct dentry *new_dentry)
270 {
271 	struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
272 	struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
273 	return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
274 }
275 
276 /**
277  * tomoyo_path_rename - Target for security_path_rename().
278  *
279  * @old_parent: Pointer to "struct path".
280  * @old_dentry: Pointer to "struct dentry".
281  * @new_parent: Pointer to "struct path".
282  * @new_dentry: Pointer to "struct dentry".
283  *
284  * Returns 0 on success, negative value otherwise.
285  */
286 static int tomoyo_path_rename(const struct path *old_parent,
287 			      struct dentry *old_dentry,
288 			      const struct path *new_parent,
289 			      struct dentry *new_dentry)
290 {
291 	struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
292 	struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
293 	return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
294 }
295 
296 /**
297  * tomoyo_file_fcntl - Target for security_file_fcntl().
298  *
299  * @file: Pointer to "struct file".
300  * @cmd:  Command for fcntl().
301  * @arg:  Argument for @cmd.
302  *
303  * Returns 0 on success, negative value otherwise.
304  */
305 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
306 			     unsigned long arg)
307 {
308 	if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
309 		return 0;
310 	return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
311 					    O_WRONLY | (arg & O_APPEND));
312 }
313 
314 /**
315  * tomoyo_file_open - Target for security_file_open().
316  *
317  * @f:    Pointer to "struct file".
318  * @cred: Pointer to "struct cred".
319  *
320  * Returns 0 on success, negative value otherwise.
321  */
322 static int tomoyo_file_open(struct file *f, const struct cred *cred)
323 {
324 	int flags = f->f_flags;
325 	/* Don't check read permission here if called from do_execve(). */
326 	if (current->in_execve)
327 		return 0;
328 	return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
329 }
330 
331 /**
332  * tomoyo_file_ioctl - Target for security_file_ioctl().
333  *
334  * @file: Pointer to "struct file".
335  * @cmd:  Command for ioctl().
336  * @arg:  Argument for @cmd.
337  *
338  * Returns 0 on success, negative value otherwise.
339  */
340 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
341 			     unsigned long arg)
342 {
343 	return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
344 }
345 
346 /**
347  * tomoyo_path_chmod - Target for security_path_chmod().
348  *
349  * @path: Pointer to "struct path".
350  * @mode: DAC permission mode.
351  *
352  * Returns 0 on success, negative value otherwise.
353  */
354 static int tomoyo_path_chmod(const struct path *path, umode_t mode)
355 {
356 	return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
357 				       mode & S_IALLUGO);
358 }
359 
360 /**
361  * tomoyo_path_chown - Target for security_path_chown().
362  *
363  * @path: Pointer to "struct path".
364  * @uid:  Owner ID.
365  * @gid:  Group ID.
366  *
367  * Returns 0 on success, negative value otherwise.
368  */
369 static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
370 {
371 	int error = 0;
372 	if (uid_valid(uid))
373 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
374 						from_kuid(&init_user_ns, uid));
375 	if (!error && gid_valid(gid))
376 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
377 						from_kgid(&init_user_ns, gid));
378 	return error;
379 }
380 
381 /**
382  * tomoyo_path_chroot - Target for security_path_chroot().
383  *
384  * @path: Pointer to "struct path".
385  *
386  * Returns 0 on success, negative value otherwise.
387  */
388 static int tomoyo_path_chroot(const struct path *path)
389 {
390 	return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
391 }
392 
393 /**
394  * tomoyo_sb_mount - Target for security_sb_mount().
395  *
396  * @dev_name: Name of device file. Maybe NULL.
397  * @path:     Pointer to "struct path".
398  * @type:     Name of filesystem type. Maybe NULL.
399  * @flags:    Mount options.
400  * @data:     Optional data. Maybe NULL.
401  *
402  * Returns 0 on success, negative value otherwise.
403  */
404 static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
405 			   const char *type, unsigned long flags, void *data)
406 {
407 	return tomoyo_mount_permission(dev_name, path, type, flags, data);
408 }
409 
410 /**
411  * tomoyo_sb_umount - Target for security_sb_umount().
412  *
413  * @mnt:   Pointer to "struct vfsmount".
414  * @flags: Unmount options.
415  *
416  * Returns 0 on success, negative value otherwise.
417  */
418 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
419 {
420 	struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
421 	return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
422 }
423 
424 /**
425  * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
426  *
427  * @old_path: Pointer to "struct path".
428  * @new_path: Pointer to "struct path".
429  *
430  * Returns 0 on success, negative value otherwise.
431  */
432 static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
433 {
434 	return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
435 }
436 
437 /**
438  * tomoyo_socket_listen - Check permission for listen().
439  *
440  * @sock:    Pointer to "struct socket".
441  * @backlog: Backlog parameter.
442  *
443  * Returns 0 on success, negative value otherwise.
444  */
445 static int tomoyo_socket_listen(struct socket *sock, int backlog)
446 {
447 	return tomoyo_socket_listen_permission(sock);
448 }
449 
450 /**
451  * tomoyo_socket_connect - Check permission for connect().
452  *
453  * @sock:     Pointer to "struct socket".
454  * @addr:     Pointer to "struct sockaddr".
455  * @addr_len: Size of @addr.
456  *
457  * Returns 0 on success, negative value otherwise.
458  */
459 static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
460 				 int addr_len)
461 {
462 	return tomoyo_socket_connect_permission(sock, addr, addr_len);
463 }
464 
465 /**
466  * tomoyo_socket_bind - Check permission for bind().
467  *
468  * @sock:     Pointer to "struct socket".
469  * @addr:     Pointer to "struct sockaddr".
470  * @addr_len: Size of @addr.
471  *
472  * Returns 0 on success, negative value otherwise.
473  */
474 static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
475 			      int addr_len)
476 {
477 	return tomoyo_socket_bind_permission(sock, addr, addr_len);
478 }
479 
480 /**
481  * tomoyo_socket_sendmsg - Check permission for sendmsg().
482  *
483  * @sock: Pointer to "struct socket".
484  * @msg:  Pointer to "struct msghdr".
485  * @size: Size of message.
486  *
487  * Returns 0 on success, negative value otherwise.
488  */
489 static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
490 				 int size)
491 {
492 	return tomoyo_socket_sendmsg_permission(sock, msg, size);
493 }
494 
495 /*
496  * tomoyo_security_ops is a "struct security_operations" which is used for
497  * registering TOMOYO.
498  */
499 static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
500 	LSM_HOOK_INIT(cred_alloc_blank, tomoyo_cred_alloc_blank),
501 	LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
502 	LSM_HOOK_INIT(cred_transfer, tomoyo_cred_transfer),
503 	LSM_HOOK_INIT(cred_free, tomoyo_cred_free),
504 	LSM_HOOK_INIT(bprm_set_creds, tomoyo_bprm_set_creds),
505 	LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
506 	LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
507 	LSM_HOOK_INIT(file_open, tomoyo_file_open),
508 	LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
509 	LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
510 	LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
511 	LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
512 	LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
513 	LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
514 	LSM_HOOK_INIT(path_link, tomoyo_path_link),
515 	LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
516 	LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
517 	LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
518 	LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
519 	LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
520 	LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
521 	LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
522 	LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
523 	LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
524 	LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
525 	LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
526 	LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
527 	LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
528 };
529 
530 /* Lock for GC. */
531 DEFINE_SRCU(tomoyo_ss);
532 
533 /**
534  * tomoyo_init - Register TOMOYO Linux as a LSM module.
535  *
536  * Returns 0.
537  */
538 static int __init tomoyo_init(void)
539 {
540 	struct cred *cred = (struct cred *) current_cred();
541 
542 	if (!security_module_enable("tomoyo"))
543 		return 0;
544 	/* register ourselves with the security framework */
545 	security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
546 	printk(KERN_INFO "TOMOYO Linux initialized\n");
547 	cred->security = &tomoyo_kernel_domain;
548 	tomoyo_mm_init();
549 	return 0;
550 }
551 
552 security_initcall(tomoyo_init);
553