1 /*
2 * Implementation of the multi-level security (MLS) policy.
3 *
4 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
5 */
6 /*
7 * Updated: Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com>
8 *
9 * Support for enhanced MLS infrastructure.
10 *
11 * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc.
12 */
13 /*
14 * Updated: Hewlett-Packard <paul@paul-moore.com>
15 *
16 * Added support to import/export the MLS label from NetLabel
17 *
18 * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
19 */
20
21 #include <linux/kernel.h>
22 #include <linux/slab.h>
23 #include <linux/string.h>
24 #include <linux/errno.h>
25 #include <net/netlabel.h>
26 #include "sidtab.h"
27 #include "mls.h"
28 #include "policydb.h"
29 #include "services.h"
30
31 /*
32 * Return the length in bytes for the MLS fields of the
33 * security context string representation of `context'.
34 */
mls_compute_context_len(struct context * context)35 int mls_compute_context_len(struct context *context)
36 {
37 int i, l, len, head, prev;
38 char *nm;
39 struct ebitmap *e;
40 struct ebitmap_node *node;
41
42 if (!policydb.mls_enabled)
43 return 0;
44
45 len = 1; /* for the beginning ":" */
46 for (l = 0; l < 2; l++) {
47 int index_sens = context->range.level[l].sens;
48 len += strlen(sym_name(&policydb, SYM_LEVELS, index_sens - 1));
49
50 /* categories */
51 head = -2;
52 prev = -2;
53 e = &context->range.level[l].cat;
54 ebitmap_for_each_positive_bit(e, node, i) {
55 if (i - prev > 1) {
56 /* one or more negative bits are skipped */
57 if (head != prev) {
58 nm = sym_name(&policydb, SYM_CATS, prev);
59 len += strlen(nm) + 1;
60 }
61 nm = sym_name(&policydb, SYM_CATS, i);
62 len += strlen(nm) + 1;
63 head = i;
64 }
65 prev = i;
66 }
67 if (prev != head) {
68 nm = sym_name(&policydb, SYM_CATS, prev);
69 len += strlen(nm) + 1;
70 }
71 if (l == 0) {
72 if (mls_level_eq(&context->range.level[0],
73 &context->range.level[1]))
74 break;
75 else
76 len++;
77 }
78 }
79
80 return len;
81 }
82
83 /*
84 * Write the security context string representation of
85 * the MLS fields of `context' into the string `*scontext'.
86 * Update `*scontext' to point to the end of the MLS fields.
87 */
mls_sid_to_context(struct context * context,char ** scontext)88 void mls_sid_to_context(struct context *context,
89 char **scontext)
90 {
91 char *scontextp, *nm;
92 int i, l, head, prev;
93 struct ebitmap *e;
94 struct ebitmap_node *node;
95
96 if (!policydb.mls_enabled)
97 return;
98
99 scontextp = *scontext;
100
101 *scontextp = ':';
102 scontextp++;
103
104 for (l = 0; l < 2; l++) {
105 strcpy(scontextp, sym_name(&policydb, SYM_LEVELS,
106 context->range.level[l].sens - 1));
107 scontextp += strlen(scontextp);
108
109 /* categories */
110 head = -2;
111 prev = -2;
112 e = &context->range.level[l].cat;
113 ebitmap_for_each_positive_bit(e, node, i) {
114 if (i - prev > 1) {
115 /* one or more negative bits are skipped */
116 if (prev != head) {
117 if (prev - head > 1)
118 *scontextp++ = '.';
119 else
120 *scontextp++ = ',';
121 nm = sym_name(&policydb, SYM_CATS, prev);
122 strcpy(scontextp, nm);
123 scontextp += strlen(nm);
124 }
125 if (prev < 0)
126 *scontextp++ = ':';
127 else
128 *scontextp++ = ',';
129 nm = sym_name(&policydb, SYM_CATS, i);
130 strcpy(scontextp, nm);
131 scontextp += strlen(nm);
132 head = i;
133 }
134 prev = i;
135 }
136
137 if (prev != head) {
138 if (prev - head > 1)
139 *scontextp++ = '.';
140 else
141 *scontextp++ = ',';
142 nm = sym_name(&policydb, SYM_CATS, prev);
143 strcpy(scontextp, nm);
144 scontextp += strlen(nm);
145 }
146
147 if (l == 0) {
148 if (mls_level_eq(&context->range.level[0],
149 &context->range.level[1]))
150 break;
151 else
152 *scontextp++ = '-';
153 }
154 }
155
156 *scontext = scontextp;
157 return;
158 }
159
mls_level_isvalid(struct policydb * p,struct mls_level * l)160 int mls_level_isvalid(struct policydb *p, struct mls_level *l)
161 {
162 struct level_datum *levdatum;
163 struct ebitmap_node *node;
164 int i;
165
166 if (!l->sens || l->sens > p->p_levels.nprim)
167 return 0;
168 levdatum = hashtab_search(p->p_levels.table,
169 sym_name(p, SYM_LEVELS, l->sens - 1));
170 if (!levdatum)
171 return 0;
172
173 ebitmap_for_each_positive_bit(&l->cat, node, i) {
174 if (i > p->p_cats.nprim)
175 return 0;
176 if (!ebitmap_get_bit(&levdatum->level->cat, i)) {
177 /*
178 * Category may not be associated with
179 * sensitivity.
180 */
181 return 0;
182 }
183 }
184
185 return 1;
186 }
187
mls_range_isvalid(struct policydb * p,struct mls_range * r)188 int mls_range_isvalid(struct policydb *p, struct mls_range *r)
189 {
190 return (mls_level_isvalid(p, &r->level[0]) &&
191 mls_level_isvalid(p, &r->level[1]) &&
192 mls_level_dom(&r->level[1], &r->level[0]));
193 }
194
195 /*
196 * Return 1 if the MLS fields in the security context
197 * structure `c' are valid. Return 0 otherwise.
198 */
mls_context_isvalid(struct policydb * p,struct context * c)199 int mls_context_isvalid(struct policydb *p, struct context *c)
200 {
201 struct user_datum *usrdatum;
202
203 if (!p->mls_enabled)
204 return 1;
205
206 if (!mls_range_isvalid(p, &c->range))
207 return 0;
208
209 if (c->role == OBJECT_R_VAL)
210 return 1;
211
212 /*
213 * User must be authorized for the MLS range.
214 */
215 if (!c->user || c->user > p->p_users.nprim)
216 return 0;
217 usrdatum = p->user_val_to_struct[c->user - 1];
218 if (!mls_range_contains(usrdatum->range, c->range))
219 return 0; /* user may not be associated with range */
220
221 return 1;
222 }
223
224 /*
225 * Set the MLS fields in the security context structure
226 * `context' based on the string representation in
227 * the string `*scontext'. Update `*scontext' to
228 * point to the end of the string representation of
229 * the MLS fields.
230 *
231 * This function modifies the string in place, inserting
232 * NULL characters to terminate the MLS fields.
233 *
234 * If a def_sid is provided and no MLS field is present,
235 * copy the MLS field of the associated default context.
236 * Used for upgraded to MLS systems where objects may lack
237 * MLS fields.
238 *
239 * Policy read-lock must be held for sidtab lookup.
240 *
241 */
mls_context_to_sid(struct policydb * pol,char oldc,char ** scontext,struct context * context,struct sidtab * s,u32 def_sid)242 int mls_context_to_sid(struct policydb *pol,
243 char oldc,
244 char **scontext,
245 struct context *context,
246 struct sidtab *s,
247 u32 def_sid)
248 {
249
250 char delim;
251 char *scontextp, *p, *rngptr;
252 struct level_datum *levdatum;
253 struct cat_datum *catdatum, *rngdatum;
254 int l, rc = -EINVAL;
255
256 if (!pol->mls_enabled) {
257 if (def_sid != SECSID_NULL && oldc)
258 *scontext += strlen(*scontext) + 1;
259 return 0;
260 }
261
262 /*
263 * No MLS component to the security context, try and map to
264 * default if provided.
265 */
266 if (!oldc) {
267 struct context *defcon;
268
269 if (def_sid == SECSID_NULL)
270 goto out;
271
272 defcon = sidtab_search(s, def_sid);
273 if (!defcon)
274 goto out;
275
276 rc = mls_context_cpy(context, defcon);
277 goto out;
278 }
279
280 /* Extract low sensitivity. */
281 scontextp = p = *scontext;
282 while (*p && *p != ':' && *p != '-')
283 p++;
284
285 delim = *p;
286 if (delim != '\0')
287 *p++ = '\0';
288
289 for (l = 0; l < 2; l++) {
290 levdatum = hashtab_search(pol->p_levels.table, scontextp);
291 if (!levdatum) {
292 rc = -EINVAL;
293 goto out;
294 }
295
296 context->range.level[l].sens = levdatum->level->sens;
297
298 if (delim == ':') {
299 /* Extract category set. */
300 while (1) {
301 scontextp = p;
302 while (*p && *p != ',' && *p != '-')
303 p++;
304 delim = *p;
305 if (delim != '\0')
306 *p++ = '\0';
307
308 /* Separate into range if exists */
309 rngptr = strchr(scontextp, '.');
310 if (rngptr != NULL) {
311 /* Remove '.' */
312 *rngptr++ = '\0';
313 }
314
315 catdatum = hashtab_search(pol->p_cats.table,
316 scontextp);
317 if (!catdatum) {
318 rc = -EINVAL;
319 goto out;
320 }
321
322 rc = ebitmap_set_bit(&context->range.level[l].cat,
323 catdatum->value - 1, 1);
324 if (rc)
325 goto out;
326
327 /* If range, set all categories in range */
328 if (rngptr) {
329 int i;
330
331 rngdatum = hashtab_search(pol->p_cats.table, rngptr);
332 if (!rngdatum) {
333 rc = -EINVAL;
334 goto out;
335 }
336
337 if (catdatum->value >= rngdatum->value) {
338 rc = -EINVAL;
339 goto out;
340 }
341
342 for (i = catdatum->value; i < rngdatum->value; i++) {
343 rc = ebitmap_set_bit(&context->range.level[l].cat, i, 1);
344 if (rc)
345 goto out;
346 }
347 }
348
349 if (delim != ',')
350 break;
351 }
352 }
353 if (delim == '-') {
354 /* Extract high sensitivity. */
355 scontextp = p;
356 while (*p && *p != ':')
357 p++;
358
359 delim = *p;
360 if (delim != '\0')
361 *p++ = '\0';
362 } else
363 break;
364 }
365
366 if (l == 0) {
367 context->range.level[1].sens = context->range.level[0].sens;
368 rc = ebitmap_cpy(&context->range.level[1].cat,
369 &context->range.level[0].cat);
370 if (rc)
371 goto out;
372 }
373 *scontext = ++p;
374 rc = 0;
375 out:
376 return rc;
377 }
378
379 /*
380 * Set the MLS fields in the security context structure
381 * `context' based on the string representation in
382 * the string `str'. This function will allocate temporary memory with the
383 * given constraints of gfp_mask.
384 */
mls_from_string(char * str,struct context * context,gfp_t gfp_mask)385 int mls_from_string(char *str, struct context *context, gfp_t gfp_mask)
386 {
387 char *tmpstr, *freestr;
388 int rc;
389
390 if (!policydb.mls_enabled)
391 return -EINVAL;
392
393 /* we need freestr because mls_context_to_sid will change
394 the value of tmpstr */
395 tmpstr = freestr = kstrdup(str, gfp_mask);
396 if (!tmpstr) {
397 rc = -ENOMEM;
398 } else {
399 rc = mls_context_to_sid(&policydb, ':', &tmpstr, context,
400 NULL, SECSID_NULL);
401 kfree(freestr);
402 }
403
404 return rc;
405 }
406
407 /*
408 * Copies the MLS range `range' into `context'.
409 */
mls_range_set(struct context * context,struct mls_range * range)410 int mls_range_set(struct context *context,
411 struct mls_range *range)
412 {
413 int l, rc = 0;
414
415 /* Copy the MLS range into the context */
416 for (l = 0; l < 2; l++) {
417 context->range.level[l].sens = range->level[l].sens;
418 rc = ebitmap_cpy(&context->range.level[l].cat,
419 &range->level[l].cat);
420 if (rc)
421 break;
422 }
423
424 return rc;
425 }
426
mls_setup_user_range(struct context * fromcon,struct user_datum * user,struct context * usercon)427 int mls_setup_user_range(struct context *fromcon, struct user_datum *user,
428 struct context *usercon)
429 {
430 if (policydb.mls_enabled) {
431 struct mls_level *fromcon_sen = &(fromcon->range.level[0]);
432 struct mls_level *fromcon_clr = &(fromcon->range.level[1]);
433 struct mls_level *user_low = &(user->range.level[0]);
434 struct mls_level *user_clr = &(user->range.level[1]);
435 struct mls_level *user_def = &(user->dfltlevel);
436 struct mls_level *usercon_sen = &(usercon->range.level[0]);
437 struct mls_level *usercon_clr = &(usercon->range.level[1]);
438
439 /* Honor the user's default level if we can */
440 if (mls_level_between(user_def, fromcon_sen, fromcon_clr))
441 *usercon_sen = *user_def;
442 else if (mls_level_between(fromcon_sen, user_def, user_clr))
443 *usercon_sen = *fromcon_sen;
444 else if (mls_level_between(fromcon_clr, user_low, user_def))
445 *usercon_sen = *user_low;
446 else
447 return -EINVAL;
448
449 /* Lower the clearance of available contexts
450 if the clearance of "fromcon" is lower than
451 that of the user's default clearance (but
452 only if the "fromcon" clearance dominates
453 the user's computed sensitivity level) */
454 if (mls_level_dom(user_clr, fromcon_clr))
455 *usercon_clr = *fromcon_clr;
456 else if (mls_level_dom(fromcon_clr, user_clr))
457 *usercon_clr = *user_clr;
458 else
459 return -EINVAL;
460 }
461
462 return 0;
463 }
464
465 /*
466 * Convert the MLS fields in the security context
467 * structure `c' from the values specified in the
468 * policy `oldp' to the values specified in the policy `newp'.
469 */
mls_convert_context(struct policydb * oldp,struct policydb * newp,struct context * c)470 int mls_convert_context(struct policydb *oldp,
471 struct policydb *newp,
472 struct context *c)
473 {
474 struct level_datum *levdatum;
475 struct cat_datum *catdatum;
476 struct ebitmap bitmap;
477 struct ebitmap_node *node;
478 int l, i;
479
480 if (!policydb.mls_enabled)
481 return 0;
482
483 for (l = 0; l < 2; l++) {
484 levdatum = hashtab_search(newp->p_levels.table,
485 sym_name(oldp, SYM_LEVELS,
486 c->range.level[l].sens - 1));
487
488 if (!levdatum)
489 return -EINVAL;
490 c->range.level[l].sens = levdatum->level->sens;
491
492 ebitmap_init(&bitmap);
493 ebitmap_for_each_positive_bit(&c->range.level[l].cat, node, i) {
494 int rc;
495
496 catdatum = hashtab_search(newp->p_cats.table,
497 sym_name(oldp, SYM_CATS, i));
498 if (!catdatum)
499 return -EINVAL;
500 rc = ebitmap_set_bit(&bitmap, catdatum->value - 1, 1);
501 if (rc)
502 return rc;
503 }
504 ebitmap_destroy(&c->range.level[l].cat);
505 c->range.level[l].cat = bitmap;
506 }
507
508 return 0;
509 }
510
mls_compute_sid(struct context * scontext,struct context * tcontext,u16 tclass,u32 specified,struct context * newcontext,bool sock)511 int mls_compute_sid(struct context *scontext,
512 struct context *tcontext,
513 u16 tclass,
514 u32 specified,
515 struct context *newcontext,
516 bool sock)
517 {
518 struct range_trans rtr;
519 struct mls_range *r;
520 struct class_datum *cladatum;
521 int default_range = 0;
522
523 if (!policydb.mls_enabled)
524 return 0;
525
526 switch (specified) {
527 case AVTAB_TRANSITION:
528 /* Look for a range transition rule. */
529 rtr.source_type = scontext->type;
530 rtr.target_type = tcontext->type;
531 rtr.target_class = tclass;
532 r = hashtab_search(policydb.range_tr, &rtr);
533 if (r)
534 return mls_range_set(newcontext, r);
535
536 if (tclass && tclass <= policydb.p_classes.nprim) {
537 cladatum = policydb.class_val_to_struct[tclass - 1];
538 if (cladatum)
539 default_range = cladatum->default_range;
540 }
541
542 switch (default_range) {
543 case DEFAULT_SOURCE_LOW:
544 return mls_context_cpy_low(newcontext, scontext);
545 case DEFAULT_SOURCE_HIGH:
546 return mls_context_cpy_high(newcontext, scontext);
547 case DEFAULT_SOURCE_LOW_HIGH:
548 return mls_context_cpy(newcontext, scontext);
549 case DEFAULT_TARGET_LOW:
550 return mls_context_cpy_low(newcontext, tcontext);
551 case DEFAULT_TARGET_HIGH:
552 return mls_context_cpy_high(newcontext, tcontext);
553 case DEFAULT_TARGET_LOW_HIGH:
554 return mls_context_cpy(newcontext, tcontext);
555 }
556
557 /* Fallthrough */
558 case AVTAB_CHANGE:
559 if ((tclass == policydb.process_class) || (sock == true))
560 /* Use the process MLS attributes. */
561 return mls_context_cpy(newcontext, scontext);
562 else
563 /* Use the process effective MLS attributes. */
564 return mls_context_cpy_low(newcontext, scontext);
565 case AVTAB_MEMBER:
566 /* Use the process effective MLS attributes. */
567 return mls_context_cpy_low(newcontext, scontext);
568
569 /* fall through */
570 }
571 return -EINVAL;
572 }
573
574 #ifdef CONFIG_NETLABEL
575 /**
576 * mls_export_netlbl_lvl - Export the MLS sensitivity levels to NetLabel
577 * @context: the security context
578 * @secattr: the NetLabel security attributes
579 *
580 * Description:
581 * Given the security context copy the low MLS sensitivity level into the
582 * NetLabel MLS sensitivity level field.
583 *
584 */
mls_export_netlbl_lvl(struct context * context,struct netlbl_lsm_secattr * secattr)585 void mls_export_netlbl_lvl(struct context *context,
586 struct netlbl_lsm_secattr *secattr)
587 {
588 if (!policydb.mls_enabled)
589 return;
590
591 secattr->attr.mls.lvl = context->range.level[0].sens - 1;
592 secattr->flags |= NETLBL_SECATTR_MLS_LVL;
593 }
594
595 /**
596 * mls_import_netlbl_lvl - Import the NetLabel MLS sensitivity levels
597 * @context: the security context
598 * @secattr: the NetLabel security attributes
599 *
600 * Description:
601 * Given the security context and the NetLabel security attributes, copy the
602 * NetLabel MLS sensitivity level into the context.
603 *
604 */
mls_import_netlbl_lvl(struct context * context,struct netlbl_lsm_secattr * secattr)605 void mls_import_netlbl_lvl(struct context *context,
606 struct netlbl_lsm_secattr *secattr)
607 {
608 if (!policydb.mls_enabled)
609 return;
610
611 context->range.level[0].sens = secattr->attr.mls.lvl + 1;
612 context->range.level[1].sens = context->range.level[0].sens;
613 }
614
615 /**
616 * mls_export_netlbl_cat - Export the MLS categories to NetLabel
617 * @context: the security context
618 * @secattr: the NetLabel security attributes
619 *
620 * Description:
621 * Given the security context copy the low MLS categories into the NetLabel
622 * MLS category field. Returns zero on success, negative values on failure.
623 *
624 */
mls_export_netlbl_cat(struct context * context,struct netlbl_lsm_secattr * secattr)625 int mls_export_netlbl_cat(struct context *context,
626 struct netlbl_lsm_secattr *secattr)
627 {
628 int rc;
629
630 if (!policydb.mls_enabled)
631 return 0;
632
633 rc = ebitmap_netlbl_export(&context->range.level[0].cat,
634 &secattr->attr.mls.cat);
635 if (rc == 0 && secattr->attr.mls.cat != NULL)
636 secattr->flags |= NETLBL_SECATTR_MLS_CAT;
637
638 return rc;
639 }
640
641 /**
642 * mls_import_netlbl_cat - Import the MLS categories from NetLabel
643 * @context: the security context
644 * @secattr: the NetLabel security attributes
645 *
646 * Description:
647 * Copy the NetLabel security attributes into the SELinux context; since the
648 * NetLabel security attribute only contains a single MLS category use it for
649 * both the low and high categories of the context. Returns zero on success,
650 * negative values on failure.
651 *
652 */
mls_import_netlbl_cat(struct context * context,struct netlbl_lsm_secattr * secattr)653 int mls_import_netlbl_cat(struct context *context,
654 struct netlbl_lsm_secattr *secattr)
655 {
656 int rc;
657
658 if (!policydb.mls_enabled)
659 return 0;
660
661 rc = ebitmap_netlbl_import(&context->range.level[0].cat,
662 secattr->attr.mls.cat);
663 if (rc != 0)
664 goto import_netlbl_cat_failure;
665
666 rc = ebitmap_cpy(&context->range.level[1].cat,
667 &context->range.level[0].cat);
668 if (rc != 0)
669 goto import_netlbl_cat_failure;
670
671 return 0;
672
673 import_netlbl_cat_failure:
674 ebitmap_destroy(&context->range.level[0].cat);
675 ebitmap_destroy(&context->range.level[1].cat);
676 return rc;
677 }
678 #endif /* CONFIG_NETLABEL */
679