1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Implementation of the multi-level security (MLS) policy. |
4 | * |
5 | * Author : Stephen Smalley, <stephen.smalley.work@gmail.com> |
6 | */ |
7 | /* |
8 | * Updated: Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com> |
9 | * |
10 | * Support for enhanced MLS infrastructure. |
11 | * |
12 | * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc. |
13 | */ |
14 | /* |
15 | * Updated: Hewlett-Packard <paul@paul-moore.com> |
16 | * |
17 | * Added support to import/export the MLS label from NetLabel |
18 | * |
19 | * (c) Copyright Hewlett-Packard Development Company, L.P., 2006 |
20 | */ |
21 | |
22 | #include <linux/kernel.h> |
23 | #include <linux/slab.h> |
24 | #include <linux/string.h> |
25 | #include <linux/errno.h> |
26 | #include <net/netlabel.h> |
27 | #include "sidtab.h" |
28 | #include "mls.h" |
29 | #include "policydb.h" |
30 | #include "services.h" |
31 | |
32 | /* |
33 | * Return the length in bytes for the MLS fields of the |
34 | * security context string representation of `context'. |
35 | */ |
36 | int mls_compute_context_len(struct policydb *p, struct context *context) |
37 | { |
38 | int i, l, len, head, prev; |
39 | char *nm; |
40 | struct ebitmap *e; |
41 | struct ebitmap_node *node; |
42 | |
43 | if (!p->mls_enabled) |
44 | return 0; |
45 | |
46 | len = 1; /* for the beginning ":" */ |
47 | for (l = 0; l < 2; l++) { |
48 | u32 index_sens = context->range.level[l].sens; |
49 | len += strlen(sym_name(p, SYM_LEVELS, index_sens - 1)); |
50 | |
51 | /* categories */ |
52 | head = -2; |
53 | prev = -2; |
54 | e = &context->range.level[l].cat; |
55 | ebitmap_for_each_positive_bit(e, node, i) { |
56 | if (i - prev > 1) { |
57 | /* one or more negative bits are skipped */ |
58 | if (head != prev) { |
59 | nm = sym_name(p, SYM_CATS, element_nr: prev); |
60 | len += strlen(nm) + 1; |
61 | } |
62 | nm = sym_name(p, SYM_CATS, element_nr: i); |
63 | len += strlen(nm) + 1; |
64 | head = i; |
65 | } |
66 | prev = i; |
67 | } |
68 | if (prev != head) { |
69 | nm = sym_name(p, SYM_CATS, element_nr: prev); |
70 | len += strlen(nm) + 1; |
71 | } |
72 | if (l == 0) { |
73 | if (mls_level_eq(l1: &context->range.level[0], |
74 | l2: &context->range.level[1])) |
75 | break; |
76 | else |
77 | len++; |
78 | } |
79 | } |
80 | |
81 | return len; |
82 | } |
83 | |
84 | /* |
85 | * Write the security context string representation of |
86 | * the MLS fields of `context' into the string `*scontext'. |
87 | * Update `*scontext' to point to the end of the MLS fields. |
88 | */ |
89 | void mls_sid_to_context(struct policydb *p, |
90 | struct context *context, |
91 | char **scontext) |
92 | { |
93 | char *scontextp, *nm; |
94 | int i, l, head, prev; |
95 | struct ebitmap *e; |
96 | struct ebitmap_node *node; |
97 | |
98 | if (!p->mls_enabled) |
99 | return; |
100 | |
101 | scontextp = *scontext; |
102 | |
103 | *scontextp = ':'; |
104 | scontextp++; |
105 | |
106 | for (l = 0; l < 2; l++) { |
107 | strcpy(p: scontextp, q: sym_name(p, SYM_LEVELS, |
108 | element_nr: context->range.level[l].sens - 1)); |
109 | scontextp += strlen(scontextp); |
110 | |
111 | /* categories */ |
112 | head = -2; |
113 | prev = -2; |
114 | e = &context->range.level[l].cat; |
115 | ebitmap_for_each_positive_bit(e, node, i) { |
116 | if (i - prev > 1) { |
117 | /* one or more negative bits are skipped */ |
118 | if (prev != head) { |
119 | if (prev - head > 1) |
120 | *scontextp++ = '.'; |
121 | else |
122 | *scontextp++ = ','; |
123 | nm = sym_name(p, SYM_CATS, element_nr: prev); |
124 | strcpy(p: scontextp, q: nm); |
125 | scontextp += strlen(nm); |
126 | } |
127 | if (prev < 0) |
128 | *scontextp++ = ':'; |
129 | else |
130 | *scontextp++ = ','; |
131 | nm = sym_name(p, SYM_CATS, element_nr: i); |
132 | strcpy(p: scontextp, q: nm); |
133 | scontextp += strlen(nm); |
134 | head = i; |
135 | } |
136 | prev = i; |
137 | } |
138 | |
139 | if (prev != head) { |
140 | if (prev - head > 1) |
141 | *scontextp++ = '.'; |
142 | else |
143 | *scontextp++ = ','; |
144 | nm = sym_name(p, SYM_CATS, element_nr: prev); |
145 | strcpy(p: scontextp, q: nm); |
146 | scontextp += strlen(nm); |
147 | } |
148 | |
149 | if (l == 0) { |
150 | if (mls_level_eq(l1: &context->range.level[0], |
151 | l2: &context->range.level[1])) |
152 | break; |
153 | else |
154 | *scontextp++ = '-'; |
155 | } |
156 | } |
157 | |
158 | *scontext = scontextp; |
159 | } |
160 | |
161 | int mls_level_isvalid(struct policydb *p, struct mls_level *l) |
162 | { |
163 | struct level_datum *levdatum; |
164 | |
165 | if (!l->sens || l->sens > p->p_levels.nprim) |
166 | return 0; |
167 | levdatum = symtab_search(s: &p->p_levels, |
168 | name: sym_name(p, SYM_LEVELS, element_nr: l->sens - 1)); |
169 | if (!levdatum) |
170 | return 0; |
171 | |
172 | /* |
173 | * Return 1 iff all the bits set in l->cat are also be set in |
174 | * levdatum->level->cat and no bit in l->cat is larger than |
175 | * p->p_cats.nprim. |
176 | */ |
177 | return ebitmap_contains(e1: &levdatum->level->cat, e2: &l->cat, |
178 | last_e2bit: p->p_cats.nprim); |
179 | } |
180 | |
181 | int mls_range_isvalid(struct policydb *p, struct mls_range *r) |
182 | { |
183 | return (mls_level_isvalid(p, l: &r->level[0]) && |
184 | mls_level_isvalid(p, l: &r->level[1]) && |
185 | mls_level_dom(l1: &r->level[1], l2: &r->level[0])); |
186 | } |
187 | |
188 | /* |
189 | * Return 1 if the MLS fields in the security context |
190 | * structure `c' are valid. Return 0 otherwise. |
191 | */ |
192 | int mls_context_isvalid(struct policydb *p, struct context *c) |
193 | { |
194 | struct user_datum *usrdatum; |
195 | |
196 | if (!p->mls_enabled) |
197 | return 1; |
198 | |
199 | if (!mls_range_isvalid(p, r: &c->range)) |
200 | return 0; |
201 | |
202 | if (c->role == OBJECT_R_VAL) |
203 | return 1; |
204 | |
205 | /* |
206 | * User must be authorized for the MLS range. |
207 | */ |
208 | if (!c->user || c->user > p->p_users.nprim) |
209 | return 0; |
210 | usrdatum = p->user_val_to_struct[c->user - 1]; |
211 | if (!mls_range_contains(usrdatum->range, c->range)) |
212 | return 0; /* user may not be associated with range */ |
213 | |
214 | return 1; |
215 | } |
216 | |
217 | /* |
218 | * Set the MLS fields in the security context structure |
219 | * `context' based on the string representation in |
220 | * the string `scontext'. |
221 | * |
222 | * This function modifies the string in place, inserting |
223 | * NULL characters to terminate the MLS fields. |
224 | * |
225 | * If a def_sid is provided and no MLS field is present, |
226 | * copy the MLS field of the associated default context. |
227 | * Used for upgraded to MLS systems where objects may lack |
228 | * MLS fields. |
229 | * |
230 | * Policy read-lock must be held for sidtab lookup. |
231 | * |
232 | */ |
233 | int mls_context_to_sid(struct policydb *pol, |
234 | char oldc, |
235 | char *scontext, |
236 | struct context *context, |
237 | struct sidtab *s, |
238 | u32 def_sid) |
239 | { |
240 | char *sensitivity, *cur_cat, *next_cat, *rngptr; |
241 | struct level_datum *levdatum; |
242 | struct cat_datum *catdatum, *rngdatum; |
243 | u32 i; |
244 | int l, rc; |
245 | char *rangep[2]; |
246 | |
247 | if (!pol->mls_enabled) { |
248 | /* |
249 | * With no MLS, only return -EINVAL if there is a MLS field |
250 | * and it did not come from an xattr. |
251 | */ |
252 | if (oldc && def_sid == SECSID_NULL) |
253 | return -EINVAL; |
254 | return 0; |
255 | } |
256 | |
257 | /* |
258 | * No MLS component to the security context, try and map to |
259 | * default if provided. |
260 | */ |
261 | if (!oldc) { |
262 | struct context *defcon; |
263 | |
264 | if (def_sid == SECSID_NULL) |
265 | return -EINVAL; |
266 | |
267 | defcon = sidtab_search(s, sid: def_sid); |
268 | if (!defcon) |
269 | return -EINVAL; |
270 | |
271 | return mls_context_cpy(dst: context, src: defcon); |
272 | } |
273 | |
274 | /* |
275 | * If we're dealing with a range, figure out where the two parts |
276 | * of the range begin. |
277 | */ |
278 | rangep[0] = scontext; |
279 | rangep[1] = strchr(scontext, '-'); |
280 | if (rangep[1]) { |
281 | rangep[1][0] = '\0'; |
282 | rangep[1]++; |
283 | } |
284 | |
285 | /* For each part of the range: */ |
286 | for (l = 0; l < 2; l++) { |
287 | /* Split sensitivity and category set. */ |
288 | sensitivity = rangep[l]; |
289 | if (sensitivity == NULL) |
290 | break; |
291 | next_cat = strchr(sensitivity, ':'); |
292 | if (next_cat) |
293 | *(next_cat++) = '\0'; |
294 | |
295 | /* Parse sensitivity. */ |
296 | levdatum = symtab_search(s: &pol->p_levels, name: sensitivity); |
297 | if (!levdatum) |
298 | return -EINVAL; |
299 | context->range.level[l].sens = levdatum->level->sens; |
300 | |
301 | /* Extract category set. */ |
302 | while (next_cat != NULL) { |
303 | cur_cat = next_cat; |
304 | next_cat = strchr(next_cat, ','); |
305 | if (next_cat != NULL) |
306 | *(next_cat++) = '\0'; |
307 | |
308 | /* Separate into range if exists */ |
309 | rngptr = strchr(cur_cat, '.'); |
310 | if (rngptr != NULL) { |
311 | /* Remove '.' */ |
312 | *rngptr++ = '\0'; |
313 | } |
314 | |
315 | catdatum = symtab_search(s: &pol->p_cats, name: cur_cat); |
316 | if (!catdatum) |
317 | return -EINVAL; |
318 | |
319 | rc = ebitmap_set_bit(e: &context->range.level[l].cat, |
320 | bit: catdatum->value - 1, value: 1); |
321 | if (rc) |
322 | return rc; |
323 | |
324 | /* If range, set all categories in range */ |
325 | if (rngptr == NULL) |
326 | continue; |
327 | |
328 | rngdatum = symtab_search(s: &pol->p_cats, name: rngptr); |
329 | if (!rngdatum) |
330 | return -EINVAL; |
331 | |
332 | if (catdatum->value >= rngdatum->value) |
333 | return -EINVAL; |
334 | |
335 | for (i = catdatum->value; i < rngdatum->value; i++) { |
336 | rc = ebitmap_set_bit(e: &context->range.level[l].cat, bit: i, value: 1); |
337 | if (rc) |
338 | return rc; |
339 | } |
340 | } |
341 | } |
342 | |
343 | /* If we didn't see a '-', the range start is also the range end. */ |
344 | if (rangep[1] == NULL) { |
345 | context->range.level[1].sens = context->range.level[0].sens; |
346 | rc = ebitmap_cpy(dst: &context->range.level[1].cat, |
347 | src: &context->range.level[0].cat); |
348 | if (rc) |
349 | return rc; |
350 | } |
351 | |
352 | return 0; |
353 | } |
354 | |
355 | /* |
356 | * Set the MLS fields in the security context structure |
357 | * `context' based on the string representation in |
358 | * the string `str'. This function will allocate temporary memory with the |
359 | * given constraints of gfp_mask. |
360 | */ |
361 | int mls_from_string(struct policydb *p, char *str, struct context *context, |
362 | gfp_t gfp_mask) |
363 | { |
364 | char *tmpstr; |
365 | int rc; |
366 | |
367 | if (!p->mls_enabled) |
368 | return -EINVAL; |
369 | |
370 | tmpstr = kstrdup(s: str, gfp: gfp_mask); |
371 | if (!tmpstr) { |
372 | rc = -ENOMEM; |
373 | } else { |
374 | rc = mls_context_to_sid(pol: p, oldc: ':', scontext: tmpstr, context, |
375 | NULL, def_sid: SECSID_NULL); |
376 | kfree(objp: tmpstr); |
377 | } |
378 | |
379 | return rc; |
380 | } |
381 | |
382 | /* |
383 | * Copies the MLS range `range' into `context'. |
384 | */ |
385 | int mls_range_set(struct context *context, |
386 | struct mls_range *range) |
387 | { |
388 | int l, rc = 0; |
389 | |
390 | /* Copy the MLS range into the context */ |
391 | for (l = 0; l < 2; l++) { |
392 | context->range.level[l].sens = range->level[l].sens; |
393 | rc = ebitmap_cpy(dst: &context->range.level[l].cat, |
394 | src: &range->level[l].cat); |
395 | if (rc) |
396 | break; |
397 | } |
398 | |
399 | return rc; |
400 | } |
401 | |
402 | int mls_setup_user_range(struct policydb *p, |
403 | struct context *fromcon, struct user_datum *user, |
404 | struct context *usercon) |
405 | { |
406 | if (p->mls_enabled) { |
407 | struct mls_level *fromcon_sen = &(fromcon->range.level[0]); |
408 | struct mls_level *fromcon_clr = &(fromcon->range.level[1]); |
409 | struct mls_level *user_low = &(user->range.level[0]); |
410 | struct mls_level *user_clr = &(user->range.level[1]); |
411 | struct mls_level *user_def = &(user->dfltlevel); |
412 | struct mls_level *usercon_sen = &(usercon->range.level[0]); |
413 | struct mls_level *usercon_clr = &(usercon->range.level[1]); |
414 | |
415 | /* Honor the user's default level if we can */ |
416 | if (mls_level_between(user_def, fromcon_sen, fromcon_clr)) |
417 | *usercon_sen = *user_def; |
418 | else if (mls_level_between(fromcon_sen, user_def, user_clr)) |
419 | *usercon_sen = *fromcon_sen; |
420 | else if (mls_level_between(fromcon_clr, user_low, user_def)) |
421 | *usercon_sen = *user_low; |
422 | else |
423 | return -EINVAL; |
424 | |
425 | /* Lower the clearance of available contexts |
426 | if the clearance of "fromcon" is lower than |
427 | that of the user's default clearance (but |
428 | only if the "fromcon" clearance dominates |
429 | the user's computed sensitivity level) */ |
430 | if (mls_level_dom(l1: user_clr, l2: fromcon_clr)) |
431 | *usercon_clr = *fromcon_clr; |
432 | else if (mls_level_dom(l1: fromcon_clr, l2: user_clr)) |
433 | *usercon_clr = *user_clr; |
434 | else |
435 | return -EINVAL; |
436 | } |
437 | |
438 | return 0; |
439 | } |
440 | |
441 | /* |
442 | * Convert the MLS fields in the security context |
443 | * structure `oldc' from the values specified in the |
444 | * policy `oldp' to the values specified in the policy `newp', |
445 | * storing the resulting context in `newc'. |
446 | */ |
447 | int mls_convert_context(struct policydb *oldp, |
448 | struct policydb *newp, |
449 | struct context *oldc, |
450 | struct context *newc) |
451 | { |
452 | struct level_datum *levdatum; |
453 | struct cat_datum *catdatum; |
454 | struct ebitmap_node *node; |
455 | u32 i; |
456 | int l; |
457 | |
458 | if (!oldp->mls_enabled || !newp->mls_enabled) |
459 | return 0; |
460 | |
461 | for (l = 0; l < 2; l++) { |
462 | char *name = sym_name(p: oldp, SYM_LEVELS, |
463 | element_nr: oldc->range.level[l].sens - 1); |
464 | |
465 | levdatum = symtab_search(s: &newp->p_levels, name); |
466 | |
467 | if (!levdatum) |
468 | return -EINVAL; |
469 | newc->range.level[l].sens = levdatum->level->sens; |
470 | |
471 | ebitmap_for_each_positive_bit(&oldc->range.level[l].cat, |
472 | node, i) { |
473 | int rc; |
474 | |
475 | catdatum = symtab_search(s: &newp->p_cats, |
476 | name: sym_name(p: oldp, SYM_CATS, element_nr: i)); |
477 | if (!catdatum) |
478 | return -EINVAL; |
479 | rc = ebitmap_set_bit(e: &newc->range.level[l].cat, |
480 | bit: catdatum->value - 1, value: 1); |
481 | if (rc) |
482 | return rc; |
483 | } |
484 | } |
485 | |
486 | return 0; |
487 | } |
488 | |
489 | int mls_compute_sid(struct policydb *p, |
490 | struct context *scontext, |
491 | struct context *tcontext, |
492 | u16 tclass, |
493 | u32 specified, |
494 | struct context *newcontext, |
495 | bool sock) |
496 | { |
497 | struct range_trans rtr; |
498 | struct mls_range *r; |
499 | struct class_datum *cladatum; |
500 | char default_range = 0; |
501 | |
502 | if (!p->mls_enabled) |
503 | return 0; |
504 | |
505 | switch (specified) { |
506 | case AVTAB_TRANSITION: |
507 | /* Look for a range transition rule. */ |
508 | rtr.source_type = scontext->type; |
509 | rtr.target_type = tcontext->type; |
510 | rtr.target_class = tclass; |
511 | r = policydb_rangetr_search(p, key: &rtr); |
512 | if (r) |
513 | return mls_range_set(context: newcontext, range: r); |
514 | |
515 | if (tclass && tclass <= p->p_classes.nprim) { |
516 | cladatum = p->class_val_to_struct[tclass - 1]; |
517 | if (cladatum) |
518 | default_range = cladatum->default_range; |
519 | } |
520 | |
521 | switch (default_range) { |
522 | case DEFAULT_SOURCE_LOW: |
523 | return mls_context_cpy_low(dst: newcontext, src: scontext); |
524 | case DEFAULT_SOURCE_HIGH: |
525 | return mls_context_cpy_high(dst: newcontext, src: scontext); |
526 | case DEFAULT_SOURCE_LOW_HIGH: |
527 | return mls_context_cpy(dst: newcontext, src: scontext); |
528 | case DEFAULT_TARGET_LOW: |
529 | return mls_context_cpy_low(dst: newcontext, src: tcontext); |
530 | case DEFAULT_TARGET_HIGH: |
531 | return mls_context_cpy_high(dst: newcontext, src: tcontext); |
532 | case DEFAULT_TARGET_LOW_HIGH: |
533 | return mls_context_cpy(dst: newcontext, src: tcontext); |
534 | case DEFAULT_GLBLUB: |
535 | return mls_context_glblub(dst: newcontext, |
536 | c1: scontext, c2: tcontext); |
537 | } |
538 | |
539 | fallthrough; |
540 | case AVTAB_CHANGE: |
541 | if ((tclass == p->process_class) || sock) |
542 | /* Use the process MLS attributes. */ |
543 | return mls_context_cpy(dst: newcontext, src: scontext); |
544 | else |
545 | /* Use the process effective MLS attributes. */ |
546 | return mls_context_cpy_low(dst: newcontext, src: scontext); |
547 | case AVTAB_MEMBER: |
548 | /* Use the process effective MLS attributes. */ |
549 | return mls_context_cpy_low(dst: newcontext, src: scontext); |
550 | } |
551 | return -EINVAL; |
552 | } |
553 | |
554 | #ifdef CONFIG_NETLABEL |
555 | /** |
556 | * mls_export_netlbl_lvl - Export the MLS sensitivity levels to NetLabel |
557 | * @p: the policy |
558 | * @context: the security context |
559 | * @secattr: the NetLabel security attributes |
560 | * |
561 | * Description: |
562 | * Given the security context copy the low MLS sensitivity level into the |
563 | * NetLabel MLS sensitivity level field. |
564 | * |
565 | */ |
566 | void mls_export_netlbl_lvl(struct policydb *p, |
567 | struct context *context, |
568 | struct netlbl_lsm_secattr *secattr) |
569 | { |
570 | if (!p->mls_enabled) |
571 | return; |
572 | |
573 | secattr->attr.mls.lvl = context->range.level[0].sens - 1; |
574 | secattr->flags |= NETLBL_SECATTR_MLS_LVL; |
575 | } |
576 | |
577 | /** |
578 | * mls_import_netlbl_lvl - Import the NetLabel MLS sensitivity levels |
579 | * @p: the policy |
580 | * @context: the security context |
581 | * @secattr: the NetLabel security attributes |
582 | * |
583 | * Description: |
584 | * Given the security context and the NetLabel security attributes, copy the |
585 | * NetLabel MLS sensitivity level into the context. |
586 | * |
587 | */ |
588 | void mls_import_netlbl_lvl(struct policydb *p, |
589 | struct context *context, |
590 | struct netlbl_lsm_secattr *secattr) |
591 | { |
592 | if (!p->mls_enabled) |
593 | return; |
594 | |
595 | context->range.level[0].sens = secattr->attr.mls.lvl + 1; |
596 | context->range.level[1].sens = context->range.level[0].sens; |
597 | } |
598 | |
599 | /** |
600 | * mls_export_netlbl_cat - Export the MLS categories to NetLabel |
601 | * @p: the policy |
602 | * @context: the security context |
603 | * @secattr: the NetLabel security attributes |
604 | * |
605 | * Description: |
606 | * Given the security context copy the low MLS categories into the NetLabel |
607 | * MLS category field. Returns zero on success, negative values on failure. |
608 | * |
609 | */ |
610 | int mls_export_netlbl_cat(struct policydb *p, |
611 | struct context *context, |
612 | struct netlbl_lsm_secattr *secattr) |
613 | { |
614 | int rc; |
615 | |
616 | if (!p->mls_enabled) |
617 | return 0; |
618 | |
619 | rc = ebitmap_netlbl_export(ebmap: &context->range.level[0].cat, |
620 | catmap: &secattr->attr.mls.cat); |
621 | if (rc == 0 && secattr->attr.mls.cat != NULL) |
622 | secattr->flags |= NETLBL_SECATTR_MLS_CAT; |
623 | |
624 | return rc; |
625 | } |
626 | |
627 | /** |
628 | * mls_import_netlbl_cat - Import the MLS categories from NetLabel |
629 | * @p: the policy |
630 | * @context: the security context |
631 | * @secattr: the NetLabel security attributes |
632 | * |
633 | * Description: |
634 | * Copy the NetLabel security attributes into the SELinux context; since the |
635 | * NetLabel security attribute only contains a single MLS category use it for |
636 | * both the low and high categories of the context. Returns zero on success, |
637 | * negative values on failure. |
638 | * |
639 | */ |
640 | int mls_import_netlbl_cat(struct policydb *p, |
641 | struct context *context, |
642 | struct netlbl_lsm_secattr *secattr) |
643 | { |
644 | int rc; |
645 | |
646 | if (!p->mls_enabled) |
647 | return 0; |
648 | |
649 | rc = ebitmap_netlbl_import(ebmap: &context->range.level[0].cat, |
650 | catmap: secattr->attr.mls.cat); |
651 | if (rc) |
652 | goto import_netlbl_cat_failure; |
653 | memcpy(&context->range.level[1].cat, &context->range.level[0].cat, |
654 | sizeof(context->range.level[0].cat)); |
655 | |
656 | return 0; |
657 | |
658 | import_netlbl_cat_failure: |
659 | ebitmap_destroy(e: &context->range.level[0].cat); |
660 | return rc; |
661 | } |
662 | #endif /* CONFIG_NETLABEL */ |
663 | |