xref: /openbmc/linux/security/tomoyo/tomoyo.c (revision cff4fa84) 
1 /*
2  * security/tomoyo/tomoyo.c
3  *
4  * Copyright (C) 2005-2011  NTT DATA CORPORATION
5  */
6 
7 #include <linux/security.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 	int rc;
76 
77 	rc = cap_bprm_set_creds(bprm);
78 	if (rc)
79 		return rc;
80 
81 	/*
82 	 * Do only if this function is called for the first time of an execve
83 	 * operation.
84 	 */
85 	if (bprm->cred_prepared)
86 		return 0;
87 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
88 	/*
89 	 * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
90 	 * for the first time.
91 	 */
92 	if (!tomoyo_policy_loaded)
93 		tomoyo_load_policy(bprm->filename);
94 #endif
95 	/*
96 	 * Release reference to "struct tomoyo_domain_info" stored inside
97 	 * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
98 	 * stored inside "bprm->cred->security" will be acquired later inside
99 	 * tomoyo_find_next_domain().
100 	 */
101 	atomic_dec(&((struct tomoyo_domain_info *)
102 		     bprm->cred->security)->users);
103 	/*
104 	 * Tell tomoyo_bprm_check_security() is called for the first time of an
105 	 * execve operation.
106 	 */
107 	bprm->cred->security = NULL;
108 	return 0;
109 }
110 
111 /**
112  * tomoyo_bprm_check_security - Target for security_bprm_check().
113  *
114  * @bprm: Pointer to "struct linux_binprm".
115  *
116  * Returns 0 on success, negative value otherwise.
117  */
118 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
119 {
120 	struct tomoyo_domain_info *domain = bprm->cred->security;
121 
122 	/*
123 	 * Execute permission is checked against pathname passed to do_execve()
124 	 * using current domain.
125 	 */
126 	if (!domain) {
127 		const int idx = tomoyo_read_lock();
128 		const int err = tomoyo_find_next_domain(bprm);
129 		tomoyo_read_unlock(idx);
130 		return err;
131 	}
132 	/*
133 	 * Read permission is checked against interpreters using next domain.
134 	 */
135 	return tomoyo_check_open_permission(domain, &bprm->file->f_path,
136 					    O_RDONLY);
137 }
138 
139 /**
140  * tomoyo_inode_getattr - Target for security_inode_getattr().
141  *
142  * @mnt:    Pointer to "struct vfsmount".
143  * @dentry: Pointer to "struct dentry".
144  *
145  * Returns 0 on success, negative value otherwise.
146  */
147 static int tomoyo_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
148 {
149 	struct path path = { mnt, dentry };
150 	return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, &path, NULL);
151 }
152 
153 /**
154  * tomoyo_path_truncate - Target for security_path_truncate().
155  *
156  * @path: Pointer to "struct path".
157  *
158  * Returns 0 on success, negative value otherwise.
159  */
160 static int tomoyo_path_truncate(struct path *path)
161 {
162 	return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
163 }
164 
165 /**
166  * tomoyo_path_unlink - Target for security_path_unlink().
167  *
168  * @parent: Pointer to "struct path".
169  * @dentry: Pointer to "struct dentry".
170  *
171  * Returns 0 on success, negative value otherwise.
172  */
173 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
174 {
175 	struct path path = { parent->mnt, dentry };
176 	return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
177 }
178 
179 /**
180  * tomoyo_path_mkdir - Target for security_path_mkdir().
181  *
182  * @parent: Pointer to "struct path".
183  * @dentry: Pointer to "struct dentry".
184  * @mode:   DAC permission mode.
185  *
186  * Returns 0 on success, negative value otherwise.
187  */
188 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
189 			     int mode)
190 {
191 	struct path path = { parent->mnt, dentry };
192 	return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
193 				       mode & S_IALLUGO);
194 }
195 
196 /**
197  * tomoyo_path_rmdir - Target for security_path_rmdir().
198  *
199  * @parent: Pointer to "struct path".
200  * @dentry: Pointer to "struct dentry".
201  *
202  * Returns 0 on success, negative value otherwise.
203  */
204 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
205 {
206 	struct path path = { parent->mnt, dentry };
207 	return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
208 }
209 
210 /**
211  * tomoyo_path_symlink - Target for security_path_symlink().
212  *
213  * @parent:   Pointer to "struct path".
214  * @dentry:   Pointer to "struct dentry".
215  * @old_name: Symlink's content.
216  *
217  * Returns 0 on success, negative value otherwise.
218  */
219 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
220 			       const char *old_name)
221 {
222 	struct path path = { parent->mnt, dentry };
223 	return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
224 }
225 
226 /**
227  * tomoyo_path_mknod - Target for security_path_mknod().
228  *
229  * @parent: Pointer to "struct path".
230  * @dentry: Pointer to "struct dentry".
231  * @mode:   DAC permission mode.
232  * @dev:    Device attributes.
233  *
234  * Returns 0 on success, negative value otherwise.
235  */
236 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
237 			     int mode, unsigned int dev)
238 {
239 	struct path path = { parent->mnt, dentry };
240 	int type = TOMOYO_TYPE_CREATE;
241 	const unsigned int perm = mode & S_IALLUGO;
242 
243 	switch (mode & S_IFMT) {
244 	case S_IFCHR:
245 		type = TOMOYO_TYPE_MKCHAR;
246 		break;
247 	case S_IFBLK:
248 		type = TOMOYO_TYPE_MKBLOCK;
249 		break;
250 	default:
251 		goto no_dev;
252 	}
253 	return tomoyo_mkdev_perm(type, &path, perm, dev);
254  no_dev:
255 	switch (mode & S_IFMT) {
256 	case S_IFIFO:
257 		type = TOMOYO_TYPE_MKFIFO;
258 		break;
259 	case S_IFSOCK:
260 		type = TOMOYO_TYPE_MKSOCK;
261 		break;
262 	}
263 	return tomoyo_path_number_perm(type, &path, perm);
264 }
265 
266 /**
267  * tomoyo_path_link - Target for security_path_link().
268  *
269  * @old_dentry: Pointer to "struct dentry".
270  * @new_dir:    Pointer to "struct path".
271  * @new_dentry: Pointer to "struct dentry".
272  *
273  * Returns 0 on success, negative value otherwise.
274  */
275 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
276 			    struct dentry *new_dentry)
277 {
278 	struct path path1 = { new_dir->mnt, old_dentry };
279 	struct path path2 = { new_dir->mnt, new_dentry };
280 	return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
281 }
282 
283 /**
284  * tomoyo_path_rename - Target for security_path_rename().
285  *
286  * @old_parent: Pointer to "struct path".
287  * @old_dentry: Pointer to "struct dentry".
288  * @new_parent: Pointer to "struct path".
289  * @new_dentry: Pointer to "struct dentry".
290  *
291  * Returns 0 on success, negative value otherwise.
292  */
293 static int tomoyo_path_rename(struct path *old_parent,
294 			      struct dentry *old_dentry,
295 			      struct path *new_parent,
296 			      struct dentry *new_dentry)
297 {
298 	struct path path1 = { old_parent->mnt, old_dentry };
299 	struct path path2 = { new_parent->mnt, new_dentry };
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_dentry_open - Target for security_dentry_open().
323  *
324  * @f:    Pointer to "struct file".
325  * @cred: Pointer to "struct cred".
326  *
327  * Returns 0 on success, negative value otherwise.
328  */
329 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
330 {
331 	int flags = f->f_flags;
332 	/* Don't check read permission here if called from do_execve(). */
333 	if (current->in_execve)
334 		return 0;
335 	return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, 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  * @dentry: Pointer to "struct dentry".
357  * @mnt:    Pointer to "struct vfsmount".
358  * @mode:   DAC permission mode.
359  *
360  * Returns 0 on success, negative value otherwise.
361  */
362 static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
363 			     mode_t mode)
364 {
365 	struct path path = { mnt, dentry };
366 	return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, &path,
367 				       mode & S_IALLUGO);
368 }
369 
370 /**
371  * tomoyo_path_chown - Target for security_path_chown().
372  *
373  * @path: Pointer to "struct path".
374  * @uid:  Owner ID.
375  * @gid:  Group ID.
376  *
377  * Returns 0 on success, negative value otherwise.
378  */
379 static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
380 {
381 	int error = 0;
382 	if (uid != (uid_t) -1)
383 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
384 	if (!error && gid != (gid_t) -1)
385 		error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, 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(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(char *dev_name, struct path *path,
413 			   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->mnt_root };
429 	return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
430 }
431 
432 /**
433  * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
434  *
435  * @old_path: Pointer to "struct path".
436  * @new_path: Pointer to "struct path".
437  *
438  * Returns 0 on success, negative value otherwise.
439  */
440 static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
441 {
442 	return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
443 }
444 
445 /*
446  * tomoyo_security_ops is a "struct security_operations" which is used for
447  * registering TOMOYO.
448  */
449 static struct security_operations tomoyo_security_ops = {
450 	.name                = "tomoyo",
451 	.cred_alloc_blank    = tomoyo_cred_alloc_blank,
452 	.cred_prepare        = tomoyo_cred_prepare,
453 	.cred_transfer	     = tomoyo_cred_transfer,
454 	.cred_free           = tomoyo_cred_free,
455 	.bprm_set_creds      = tomoyo_bprm_set_creds,
456 	.bprm_check_security = tomoyo_bprm_check_security,
457 	.file_fcntl          = tomoyo_file_fcntl,
458 	.dentry_open         = tomoyo_dentry_open,
459 	.path_truncate       = tomoyo_path_truncate,
460 	.path_unlink         = tomoyo_path_unlink,
461 	.path_mkdir          = tomoyo_path_mkdir,
462 	.path_rmdir          = tomoyo_path_rmdir,
463 	.path_symlink        = tomoyo_path_symlink,
464 	.path_mknod          = tomoyo_path_mknod,
465 	.path_link           = tomoyo_path_link,
466 	.path_rename         = tomoyo_path_rename,
467 	.inode_getattr       = tomoyo_inode_getattr,
468 	.file_ioctl          = tomoyo_file_ioctl,
469 	.path_chmod          = tomoyo_path_chmod,
470 	.path_chown          = tomoyo_path_chown,
471 	.path_chroot         = tomoyo_path_chroot,
472 	.sb_mount            = tomoyo_sb_mount,
473 	.sb_umount           = tomoyo_sb_umount,
474 	.sb_pivotroot        = tomoyo_sb_pivotroot,
475 };
476 
477 /* Lock for GC. */
478 struct srcu_struct tomoyo_ss;
479 
480 /**
481  * tomoyo_init - Register TOMOYO Linux as a LSM module.
482  *
483  * Returns 0.
484  */
485 static int __init tomoyo_init(void)
486 {
487 	struct cred *cred = (struct cred *) current_cred();
488 
489 	if (!security_module_enable(&tomoyo_security_ops))
490 		return 0;
491 	/* register ourselves with the security framework */
492 	if (register_security(&tomoyo_security_ops) ||
493 	    init_srcu_struct(&tomoyo_ss))
494 		panic("Failure registering TOMOYO Linux");
495 	printk(KERN_INFO "TOMOYO Linux initialized\n");
496 	cred->security = &tomoyo_kernel_domain;
497 	tomoyo_mm_init();
498 	return 0;
499 }
500 
501 security_initcall(tomoyo_init);
502