summaryrefslogtreecommitdiffstats
path: root/security/apparmor/domain.c
blob: 6a54d2ffa84012fc7fd27aef18c7fa0410e050e3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
/*
 * AppArmor security module
 *
 * This file contains AppArmor policy attachment and domain transitions
 *
 * Copyright (C) 2002-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 */

#include <linux/errno.h>
#include <linux/fdtable.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/syscalls.h>
#include <linux/tracehook.h>
#include <linux/personality.h>

#include "include/audit.h"
#include "include/apparmorfs.h"
#include "include/context.h"
#include "include/domain.h"
#include "include/file.h"
#include "include/ipc.h"
#include "include/match.h"
#include "include/path.h"
#include "include/policy.h"
#include "include/policy_ns.h"

/**
 * aa_free_domain_entries - free entries in a domain table
 * @domain: the domain table to free  (MAYBE NULL)
 */
void aa_free_domain_entries(struct aa_domain *domain)
{
	int i;
	if (domain) {
		if (!domain->table)
			return;

		for (i = 0; i < domain->size; i++)
			kzfree(domain->table[i]);
		kzfree(domain->table);
		domain->table = NULL;
	}
}

/**
 * may_change_ptraced_domain - check if can change profile on ptraced task
 * @to_label: profile to change to  (NOT NULL)
 * @info: message if there is an error
 *
 * Check if current is ptraced and if so if the tracing task is allowed
 * to trace the new domain
 *
 * Returns: %0 or error if change not allowed
 */
static int may_change_ptraced_domain(struct aa_label *to_label,
				     const char **info)
{
	struct task_struct *tracer;
	struct aa_label *tracerl = NULL;
	int error = 0;

	rcu_read_lock();
	tracer = ptrace_parent(current);
	if (tracer)
		/* released below */
		tracerl = aa_get_task_label(tracer);

	/* not ptraced */
	if (!tracer || unconfined(tracerl))
		goto out;

	error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);

out:
	rcu_read_unlock();
	aa_put_label(tracerl);

	if (error)
		*info = "ptrace prevents transition";
	return error;
}

/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
 * specifically this is an exact copy of aa_label_match except
 * aa_compute_perms is replaced with aa_compute_fperms
 * and policy.dfa with file.dfa
 ****/
/* match a profile and its associated ns component if needed
 * Assumes visibility test has already been done.
 * If a subns profile is not to be matched should be prescreened with
 * visibility test.
 */
static inline unsigned int match_component(struct aa_profile *profile,
					   struct aa_profile *tp,
					   bool stack, unsigned int state)
{
	const char *ns_name;

	if (stack)
		state = aa_dfa_match(profile->file.dfa, state, "&");
	if (profile->ns == tp->ns)
		return aa_dfa_match(profile->file.dfa, state, tp->base.hname);

	/* try matching with namespace name and then profile */
	ns_name = aa_ns_name(profile->ns, tp->ns, true);
	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
	state = aa_dfa_match(profile->file.dfa, state, ns_name);
	state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
	return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
}

/**
 * label_compound_match - find perms for full compound label
 * @profile: profile to find perms for
 * @label: label to check access permissions for
 * @stack: whether this is a stacking request
 * @start: state to start match in
 * @subns: whether to do permission checks on components in a subns
 * @request: permissions to request
 * @perms: perms struct to set
 *
 * Returns: 0 on success else ERROR
 *
 * For the label A//&B//&C this does the perm match for A//&B//&C
 * @perms should be preinitialized with allperms OR a previous permission
 *        check to be stacked.
 */
static int label_compound_match(struct aa_profile *profile,
				struct aa_label *label, bool stack,
				unsigned int state, bool subns, u32 request,
				struct aa_perms *perms)
{
	struct aa_profile *tp;
	struct label_it i;
	struct path_cond cond = { };

	/* find first subcomponent that is visible */
	label_for_each(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = match_component(profile, tp, stack, state);
		if (!state)
			goto fail;
		goto next;
	}

	/* no component visible */
	*perms = allperms;
	return 0;

next:
	label_for_each_cont(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = aa_dfa_match(profile->file.dfa, state, "//&");
		state = match_component(profile, tp, false, state);
		if (!state)
			goto fail;
	}
	*perms = aa_compute_fperms(profile->file.dfa, state, &cond);
	aa_apply_modes_to_perms(profile, perms);
	if ((perms->allow & request) != request)
		return -EACCES;

	return 0;

fail:
	*perms = nullperms;
	return -EACCES;
}

/**
 * label_components_match - find perms for all subcomponents of a label
 * @profile: profile to find perms for
 * @label: label to check access permissions for
 * @stack: whether this is a stacking request
 * @start: state to start match in
 * @subns: whether to do permission checks on components in a subns
 * @request: permissions to request
 * @perms: an initialized perms struct to add accumulation to
 *
 * Returns: 0 on success else ERROR
 *
 * For the label A//&B//&C this does the perm match for each of A and B and C
 * @perms should be preinitialized with allperms OR a previous permission
 *        check to be stacked.
 */
static int label_components_match(struct aa_profile *profile,
				  struct aa_label *label, bool stack,
				  unsigned int start, bool subns, u32 request,
				  struct aa_perms *perms)
{
	struct aa_profile *tp;
	struct label_it i;
	struct aa_perms tmp;
	struct path_cond cond = { };
	unsigned int state = 0;

	/* find first subcomponent to test */
	label_for_each(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = match_component(profile, tp, stack, start);
		if (!state)
			goto fail;
		goto next;
	}

	/* no subcomponents visible - no change in perms */
	return 0;

next:
	tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
	aa_apply_modes_to_perms(profile, &tmp);
	aa_perms_accum(perms, &tmp);
	label_for_each_cont(i, label, tp) {
		if (!aa_ns_visible(profile->ns, tp->ns, subns))
			continue;
		state = match_component(profile, tp, stack, start);
		if (!state)
			goto fail;
		tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
		aa_apply_modes_to_perms(profile, &tmp);
		aa_perms_accum(perms, &tmp);
	}

	if ((perms->allow & request) != request)
		return -EACCES;

	return 0;

fail:
	*perms = nullperms;
	return -EACCES;
}

/**
 * label_match - do a multi-component label match
 * @profile: profile to match against (NOT NULL)
 * @label: label to match (NOT NULL)
 * @stack: whether this is a stacking request
 * @state: state to start in
 * @subns: whether to match subns components
 * @request: permission request
 * @perms: Returns computed perms (NOT NULL)
 *
 * Returns: the state the match finished in, may be the none matching state
 */
static int label_match(struct aa_profile *profile, struct aa_label *label,
		       bool stack, unsigned int state, bool subns, u32 request,
		       struct aa_perms *perms)
{
	int error;

	*perms = nullperms;
	error = label_compound_match(profile, label, stack, state, subns,
				     request, perms);
	if (!error)
		return error;

	*perms = allperms;
	return label_components_match(profile, label, stack, state, subns,
				      request, perms);
}

/******* end TODO: dedup *****/

/**
 * change_profile_perms - find permissions for change_profile
 * @profile: the current profile  (NOT NULL)
 * @target: label to transition to (NOT NULL)
 * @stack: whether this is a stacking request
 * @request: requested perms
 * @start: state to start matching in
 *
 *
 * Returns: permission set
 *
 * currently only matches full label A//&B//&C or individual components A, B, C
 * not arbitrary combinations. Eg. A//&B, C
 */
static int change_profile_perms(struct aa_profile *profile,
				struct aa_label *target, bool stack,
				u32 request, unsigned int start,
				struct aa_perms *perms)
{
	if (profile_unconfined(profile)) {
		perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
		perms->audit = perms->quiet = perms->kill = 0;
		return 0;
	}

	/* TODO: add profile in ns screening */
	return label_match(profile, target, stack, start, true, request, perms);
}

/**
 * __attach_match_ - find an attachment match
 * @name - to match against  (NOT NULL)
 * @head - profile list to walk  (NOT NULL)
 * @info - info message if there was an error (NOT NULL)
 *
 * Do a linear search on the profiles in the list.  There is a matching
 * preference where an exact match is preferred over a name which uses
 * expressions to match, and matching expressions with the greatest
 * xmatch_len are preferred.
 *
 * Requires: @head not be shared or have appropriate locks held
 *
 * Returns: profile or NULL if no match found
 */
static struct aa_profile *__attach_match(const char *name,
					 struct list_head *head,
					 const char **info)
{
	int len = 0;
	bool conflict = false;
	struct aa_profile *profile, *candidate = NULL;

	list_for_each_entry_rcu(profile, head, base.list) {
		if (profile->label.flags & FLAG_NULL &&
		    &profile->label == ns_unconfined(profile->ns))
			continue;

		if (profile->xmatch) {
			if (profile->xmatch_len >= len) {
				unsigned int state;
				u32 perm;

				state = aa_dfa_match(profile->xmatch,
						     DFA_START, name);
				perm = dfa_user_allow(profile->xmatch, state);
				/* any accepting state means a valid match. */
				if (perm & MAY_EXEC) {
					if (profile->xmatch_len == len) {
						conflict = true;
						continue;
					}
					candidate = profile;
					len = profile->xmatch_len;
					conflict = false;
				}
			}
		} else if (!strcmp(profile->base.name, name))
			/* exact non-re match, no more searching required */
			return profile;
	}

	if (conflict) {
		*info = "conflicting profile attachments";
		return NULL;
	}

	return candidate;
}

/**
 * find_attach - do attachment search for unconfined processes
 * @ns: the current namespace  (NOT NULL)
 * @list: list to search  (NOT NULL)
 * @name: the executable name to match against  (NOT NULL)
 * @info: info message if there was an error
 *
 * Returns: label or NULL if no match found
 */
static struct aa_label *find_attach(struct aa_ns *ns, struct list_head *list,
				    const char *name, const char **info)
{
	struct aa_profile *profile;

	rcu_read_lock();
	profile = aa_get_profile(__attach_match(name, list, info));
	rcu_read_unlock();

	return profile ? &profile->label : NULL;
}

static const char *next_name(int xtype, const char *name)
{
	return NULL;
}

/**
 * x_table_lookup - lookup an x transition name via transition table
 * @profile: current profile (NOT NULL)
 * @xindex: index into x transition table
 * @name: returns: name tested to find label (NOT NULL)
 *
 * Returns: refcounted label, or NULL on failure (MAYBE NULL)
 */
struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
				const char **name)
{
	struct aa_label *label = NULL;
	u32 xtype = xindex & AA_X_TYPE_MASK;
	int index = xindex & AA_X_INDEX_MASK;

	AA_BUG(!name);

	/* index is guaranteed to be in range, validated at load time */
	/* TODO: move lookup parsing to unpack time so this is a straight
	 *       index into the resultant label
	 */
	for (*name = profile->file.trans.table[index]; !label && *name;
	     *name = next_name(xtype, *name)) {
		if (xindex & AA_X_CHILD) {
			struct aa_profile *new_profile;
			/* release by caller */
			new_profile = aa_find_child(profile, *name);
			if (new_profile)
				label = &new_profile->label;
			continue;
		}
		label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
				       true, false);
		if (IS_ERR(label))
			label = NULL;
	}

	/* released by caller */

	return label;
}

/**
 * x_to_label - get target label for a given xindex
 * @profile: current profile  (NOT NULL)
 * @name: name to lookup (NOT NULL)
 * @xindex: index into x transition table
 * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
 *
 * find label for a transition index
 *
 * Returns: refcounted label or NULL if not found available
 */
static struct aa_label *x_to_label(struct aa_profile *profile,
				   const char *name, u32 xindex,
				   const char **lookupname,
				   const char **info)
{
	struct aa_label *new = NULL;
	struct aa_ns *ns = profile->ns;
	u32 xtype = xindex & AA_X_TYPE_MASK;
	const char *stack = NULL;

	switch (xtype) {
	case AA_X_NONE:
		/* fail exec unless ix || ux fallback - handled by caller */
		*lookupname = NULL;
		break;
	case AA_X_TABLE:
		/* TODO: fix when perm mapping done at unload */
		stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
		if (*stack != '&') {
			/* released by caller */
			new = x_table_lookup(profile, xindex, lookupname);
			stack = NULL;
			break;
		}
		/* fall through to X_NAME */
	case AA_X_NAME:
		if (xindex & AA_X_CHILD)
			/* released by caller */
			new = find_attach(ns, &profile->base.profiles,
					  name, info);
		else
			/* released by caller */
			new = find_attach(ns, &ns->base.profiles,
					  name, info);
		*lookupname = name;
		break;
	}

	if (!new) {
		if (xindex & AA_X_INHERIT) {
			/* (p|c|n)ix - don't change profile but do
			 * use the newest version
			 */
			*info = "ix fallback";
			/* no profile && no error */
			new = aa_get_newest_label(&profile->label);
		} else if (xindex & AA_X_UNCONFINED) {
			new = aa_get_newest_label(ns_unconfined(profile->ns));
			*info = "ux fallback";
		}
	}

	if (new && stack) {
		/* base the stack on post domain transition */
		struct aa_label *base = new;

		new = aa_label_parse(base, stack, GFP_ATOMIC, true, false);
		if (IS_ERR(new))
			new = NULL;
		aa_put_label(base);
	}

	/* released by caller */
	return new;
}

static struct aa_label *profile_transition(struct aa_profile *profile,
					   const struct linux_binprm *bprm,
					   char *buffer, struct path_cond *cond,
					   bool *secure_exec)
{
	struct aa_label *new = NULL;
	const char *info = NULL, *name = NULL, *target = NULL;
	unsigned int state = profile->file.start;
	struct aa_perms perms = {};
	bool nonewprivs = false;
	int error = 0;

	AA_BUG(!profile);
	AA_BUG(!bprm);
	AA_BUG(!buffer);

	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
			     &name, &info, profile->disconnected);
	if (error) {
		if (profile_unconfined(profile) ||
		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
			AA_DEBUG("name lookup ix on error");
			error = 0;
			new = aa_get_newest_label(&profile->label);
		}
		name = bprm->filename;
		goto audit;
	}

	if (profile_unconfined(profile)) {
		new = find_attach(profile->ns, &profile->ns->base.profiles,
				  name, &info);
		if (new) {
			AA_DEBUG("unconfined attached to new label");
			return new;
		}
		AA_DEBUG("unconfined exec no attachment");
		return aa_get_newest_label(&profile->label);
	}

	/* find exec permissions for name */
	state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
	if (perms.allow & MAY_EXEC) {
		/* exec permission determine how to transition */
		new = x_to_label(profile, name, perms.xindex, &target, &info);
		if (new && new->proxy == profile->label.proxy && info) {
			/* hack ix fallback - improve how this is detected */
			goto audit;
		} else if (!new) {
			error = -EACCES;
			info = "profile transition not found";
			/* remove MAY_EXEC to audit as failure */
			perms.allow &= ~MAY_EXEC;
		}
	} else if (COMPLAIN_MODE(profile)) {
		/* no exec permission - learning mode */
		struct aa_profile *new_profile = NULL;
		char *n = kstrdup(name, GFP_ATOMIC);

		if (n) {
			/* name is ptr into buffer */
			long pos = name - buffer;
			/* break per cpu buffer hold */
			put_buffers(buffer);
			new_profile = aa_new_null_profile(profile, false, n,
							  GFP_KERNEL);
			get_buffers(buffer);
			name = buffer + pos;
			strcpy((char *)name, n);
			kfree(n);
		}
		if (!new_profile) {
			error = -ENOMEM;
			info = "could not create null profile";
		} else {
			error = -EACCES;
			new = &new_profile->label;
		}
		perms.xindex |= AA_X_UNSAFE;
	} else
		/* fail exec */
		error = -EACCES;

	if (!new)
		goto audit;

	/* Policy has specified a domain transitions. if no_new_privs and
	 * confined and not transitioning to the current domain fail.
	 *
	 * NOTE: Domain transitions from unconfined and to stritly stacked
	 * subsets are allowed even when no_new_privs is set because this
	 * aways results in a further reduction of permissions.
	 */
	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
	    !profile_unconfined(profile) &&
	    !aa_label_is_subset(new, &profile->label)) {
		error = -EPERM;
		info = "no new privs";
		nonewprivs = true;
		perms.allow &= ~MAY_EXEC;
		goto audit;
	}

	if (!(perms.xindex & AA_X_UNSAFE)) {
		if (DEBUG_ON) {
			dbg_printk("apparmor: scrubbing environment variables"
				   " for %s profile=", name);
			aa_label_printk(new, GFP_ATOMIC);
			dbg_printk("\n");
		}
		*secure_exec = true;
	}

audit:
	aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
		      cond->uid, info, error);
	if (!new || nonewprivs) {
		aa_put_label(new);
		return ERR_PTR(error);
	}

	return new;
}

static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
			  bool stack, const struct linux_binprm *bprm,
			  char *buffer, struct path_cond *cond,
			  bool *secure_exec)
{
	unsigned int state = profile->file.start;
	struct aa_perms perms = {};
	const char *xname = NULL, *info = "change_profile onexec";
	int error = -EACCES;

	AA_BUG(!profile);
	AA_BUG(!onexec);
	AA_BUG(!bprm);
	AA_BUG(!buffer);

	if (profile_unconfined(profile)) {
		/* change_profile on exec already granted */
		/*
		 * NOTE: Domain transitions from unconfined are allowed
		 * even when no_new_privs is set because this aways results
		 * in a further reduction of permissions.
		 */
		return 0;
	}

	error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
			     &xname, &info, profile->disconnected);
	if (error) {
		if (profile_unconfined(profile) ||
		    (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
			AA_DEBUG("name lookup ix on error");
			error = 0;
		}
		xname = bprm->filename;
		goto audit;
	}

	/* find exec permissions for name */
	state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
	if (!(perms.allow & AA_MAY_ONEXEC)) {
		info = "no change_onexec valid for executable";
		goto audit;
	}
	/* test if this exec can be paired with change_profile onexec.
	 * onexec permission is linked to exec with a standard pairing
	 * exec\0change_profile
	 */
	state = aa_dfa_null_transition(profile->file.dfa, state);
	error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
				     state, &perms);
	if (error) {
		perms.allow &= ~AA_MAY_ONEXEC;
		goto audit;
	}
	/* Policy has specified a domain transitions. if no_new_privs and
	 * confined and not transitioning to the current domain fail.
	 *
	 * NOTE: Domain transitions from unconfined and to stritly stacked
	 * subsets are allowed even when no_new_privs is set because this
	 * aways results in a further reduction of permissions.
	 */
	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
	    !profile_unconfined(profile) &&
	    !aa_label_is_subset(onexec, &profile->label)) {
		error = -EPERM;
		info = "no new privs";
		perms.allow &= ~AA_MAY_ONEXEC;
		goto audit;
	}

	if (!(perms.xindex & AA_X_UNSAFE)) {
		if (DEBUG_ON) {
			dbg_printk("apparmor: scrubbing environment "
				   "variables for %s label=", xname);
			aa_label_printk(onexec, GFP_ATOMIC);
			dbg_printk("\n");
		}
		*secure_exec = true;
	}

audit:
	return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
			     NULL, onexec, cond->uid, info, error);
}

/* ensure none ns domain transitions are correctly applied with onexec */

static struct aa_label *handle_onexec(struct aa_label *label,
				      struct aa_label *onexec, bool stack,
				      const struct linux_binprm *bprm,
				      char *buffer, struct path_cond *cond,
				      bool *unsafe)
{
	struct aa_profile *profile;
	struct aa_label *new;
	int error;

	AA_BUG(!label);
	AA_BUG(!onexec);
	AA_BUG(!bprm);
	AA_BUG(!buffer);

	if (!stack) {
		error = fn_for_each_in_ns(label, profile,
				profile_onexec(profile, onexec, stack,
					       bprm, buffer, cond, unsafe));
		if (error)
			return ERR_PTR(error);
		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
				aa_get_newest_label(onexec),
				profile_transition(profile, bprm, buffer,
						   cond, unsafe));

	} else {
		/* TODO: determine how much we want to losen this */
		error = fn_for_each_in_ns(label, profile,
				profile_onexec(profile, onexec, stack, bprm,
					       buffer, cond, unsafe));
		if (error)
			return ERR_PTR(error);
		new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
				aa_label_merge(&profile->label, onexec,
					       GFP_ATOMIC),
				profile_transition(profile, bprm, buffer,
						   cond, unsafe));
	}

	if (new)
		return new;

	/* TODO: get rid of GLOBAL_ROOT_UID */
	error = fn_for_each_in_ns(label, profile,
			aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
				      AA_MAY_ONEXEC, bprm->filename, NULL,
				      onexec, GLOBAL_ROOT_UID,
				      "failed to build target label", -ENOMEM));
	return ERR_PTR(error);
}

/**
 * apparmor_bprm_set_creds - set the new creds on the bprm struct
 * @bprm: binprm for the exec  (NOT NULL)
 *
 * Returns: %0 or error on failure
 *
 * TODO: once the other paths are done see if we can't refactor into a fn
 */
int apparmor_bprm_set_creds(struct linux_binprm *bprm)
{
	struct aa_task_ctx *ctx;
	struct aa_label *label, *new = NULL;
	struct aa_profile *profile;
	char *buffer = NULL;
	const char *info = NULL;
	int error = 0;
	bool unsafe = false;
	struct path_cond cond = {
		file_inode(bprm->file)->i_uid,
		file_inode(bprm->file)->i_mode
	};

	if (bprm->called_set_creds)
		return 0;

	ctx = cred_ctx(bprm->cred);
	AA_BUG(!ctx);

	label = aa_get_newest_label(ctx->label);

	/* buffer freed below, name is pointer into buffer */
	get_buffers(buffer);
	/* Test for onexec first as onexec override other x transitions. */
	if (ctx->onexec)
		new = handle_onexec(label, ctx->onexec, ctx->token,
				    bprm, buffer, &cond, &unsafe);
	else
		new = fn_label_build(label, profile, GFP_ATOMIC,
				profile_transition(profile, bprm, buffer,
						   &cond, &unsafe));

	AA_BUG(!new);
	if (IS_ERR(new)) {
		error = PTR_ERR(new);
		goto done;
	} else if (!new) {
		error = -ENOMEM;
		goto done;
	}

	/* TODO: Add ns level no_new_privs subset test */

	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
		/* FIXME: currently don't mediate shared state */
		;
	}

	if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
		/* TODO: test needs to be profile of label to new */
		error = may_change_ptraced_domain(new, &info);
		if (error)
			goto audit;
	}

	if (unsafe) {
		if (DEBUG_ON) {
			dbg_printk("scrubbing environment variables for %s "
				   "label=", bprm->filename);
			aa_label_printk(new, GFP_ATOMIC);
			dbg_printk("\n");
		}
		bprm->secureexec = 1;
	}

	if (label->proxy != new->proxy) {
		/* when transitioning clear unsafe personality bits */
		if (DEBUG_ON) {
			dbg_printk("apparmor: clearing unsafe personality "
				   "bits. %s label=", bprm->filename);
			aa_label_printk(new, GFP_ATOMIC);
			dbg_printk("\n");
		}
		bprm->per_clear |= PER_CLEAR_ON_SETID;
	}
	aa_put_label(ctx->label);
	/* transfer reference, released when ctx is freed */
	ctx->label = new;

done:
	/* clear out temporary/transitional state from the context */
	aa_clear_task_ctx_trans(ctx);

	aa_put_label(label);
	put_buffers(buffer);

	return error;

audit:
	error = fn_for_each(label, profile,
			aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
				      bprm->filename, NULL, new,
				      file_inode(bprm->file)->i_uid, info,
				      error));
	aa_put_label(new);
	goto done;
}

/*
 * Functions for self directed profile change
 */


/* helper fn for change_hat
 *
 * Returns: label for hat transition OR ERR_PTR.  Does NOT return NULL
 */
static struct aa_label *build_change_hat(struct aa_profile *profile,
					 const char *name, bool sibling)
{
	struct aa_profile *root, *hat = NULL;
	const char *info = NULL;
	int error = 0;

	if (sibling && PROFILE_IS_HAT(profile)) {
		root = aa_get_profile_rcu(&profile->parent);
	} else if (!sibling && !PROFILE_IS_HAT(profile)) {
		root = aa_get_profile(profile);
	} else {
		info = "conflicting target types";
		error = -EPERM;
		goto audit;
	}

	hat = aa_find_child(root, name);
	if (!hat) {
		error = -ENOENT;
		if (COMPLAIN_MODE(profile)) {
			hat = aa_new_null_profile(profile, true, name,
						  GFP_KERNEL);
			if (!hat) {
				info = "failed null profile create";
				error = -ENOMEM;
			}
		}
	}
	aa_put_profile(root);

audit:
	aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
		      name, hat ? hat->base.hname : NULL,
		      hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL,
		      error);
	if (!hat || (error && error != -ENOENT))
		return ERR_PTR(error);
	/* if hat && error - complain mode, already audited and we adjust for
	 * complain mode allow by returning hat->label
	 */
	return &hat->label;
}

/* helper fn for changing into a hat
 *
 * Returns: label for hat transition or ERR_PTR. Does not return NULL
 */
static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
				   int count, int flags)
{
	struct aa_profile *profile, *root, *hat = NULL;
	struct aa_label *new;
	struct label_it it;
	bool sibling = false;
	const char *name, *info = NULL;
	int i, error;

	AA_BUG(!label);
	AA_BUG(!hats);
	AA_BUG(count < 1);

	if (PROFILE_IS_HAT(labels_profile(label)))
		sibling = true;

	/*find first matching hat */
	for (i = 0; i < count && !hat; i++) {
		name = hats[i];
		label_for_each_in_ns(it, labels_ns(label), label, profile) {
			if (sibling && PROFILE_IS_HAT(profile)) {
				root = aa_get_profile_rcu(&profile->parent);
			} else if (!sibling && !PROFILE_IS_HAT(profile)) {
				root = aa_get_profile(profile);
			} else {	/* conflicting change type */
				info = "conflicting targets types";
				error = -EPERM;
				goto fail;
			}
			hat = aa_find_child(root, name);
			aa_put_profile(root);
			if (!hat) {
				if (!COMPLAIN_MODE(profile))
					goto outer_continue;
				/* complain mode succeed as if hat */
			} else if (!PROFILE_IS_HAT(hat)) {
				info = "target not hat";
				error = -EPERM;
				aa_put_profile(hat);
				goto fail;
			}
			aa_put_profile(hat);
		}
		/* found a hat for all profiles in ns */
		goto build;
outer_continue:
	;
	}
	/* no hats that match, find appropriate error
	 *
	 * In complain mode audit of the failure is based off of the first
	 * hat supplied.  This is done due how userspace interacts with
	 * change_hat.
	 */
	name = NULL;
	label_for_each_in_ns(it, labels_ns(label), label, profile) {
		if (!list_empty(&profile->base.profiles)) {
			info = "hat not found";
			error = -ENOENT;
			goto fail;
		}
	}
	info = "no hats defined";
	error = -ECHILD;

fail:
	label_for_each_in_ns(it, labels_ns(label), label, profile) {
		/*
		 * no target as it has failed to be found or built
		 *
		 * change_hat uses probing and should not log failures
		 * related to missing hats
		 */
		/* TODO: get rid of GLOBAL_ROOT_UID */
		if (count > 1 || COMPLAIN_MODE(profile)) {
			aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
				      AA_MAY_CHANGEHAT, name, NULL, NULL,
				      GLOBAL_ROOT_UID, info, error);
		}
	}
	return ERR_PTR(error);

build:
	new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
				   build_change_hat(profile, name, sibling),
				   aa_get_label(&profile->label));
	if (!new) {
		info = "label build failed";
		error = -ENOMEM;
		goto fail;
	} /* else if (IS_ERR) build_change_hat has logged error so return new */

	return new;
}

/**
 * aa_change_hat - change hat to/from subprofile
 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
 * @count: number of hat names in @hats
 * @token: magic value to validate the hat change
 * @flags: flags affecting behavior of the change
 *
 * Returns %0 on success, error otherwise.
 *
 * Change to the first profile specified in @hats that exists, and store
 * the @hat_magic in the current task context.  If the count == 0 and the
 * @token matches that stored in the current task context, return to the
 * top level profile.
 *
 * change_hat only applies to profiles in the current ns, and each profile
 * in the ns must make the same transition otherwise change_hat will fail.
 */
int aa_change_hat(const char *hats[], int count, u64 token, int flags)
{
	const struct cred *cred;
	struct aa_task_ctx *ctx;
	struct aa_label *label, *previous, *new = NULL, *target = NULL;
	struct aa_profile *profile;
	struct aa_perms perms = {};
	const char *info = NULL;
	int error = 0;

	/*
	 * Fail explicitly requested domain transitions if no_new_privs.
	 * There is no exception for unconfined as change_hat is not
	 * available.
	 */
	if (task_no_new_privs(current)) {
		/* not an apparmor denial per se, so don't log it */
		AA_DEBUG("no_new_privs - change_hat denied");
		return -EPERM;
	}

	/* released below */
	cred = get_current_cred();
	ctx = cred_ctx(cred);
	label = aa_get_newest_cred_label(cred);
	previous = aa_get_newest_label(ctx->previous);

	if (unconfined(label)) {
		info = "unconfined can not change_hat";
		error = -EPERM;
		goto fail;
	}

	if (count) {
		new = change_hat(label, hats, count, flags);
		AA_BUG(!new);
		if (IS_ERR(new)) {
			error = PTR_ERR(new);
			new = NULL;
			/* already audited */
			goto out;
		}

		error = may_change_ptraced_domain(new, &info);
		if (error)
			goto fail;

		if (flags & AA_CHANGE_TEST)
			goto out;

		target = new;
		error = aa_set_current_hat(new, token);
		if (error == -EACCES)
			/* kill task in case of brute force attacks */
			goto kill;
	} else if (previous && !(flags & AA_CHANGE_TEST)) {
		/* Return to saved label.  Kill task if restore fails
		 * to avoid brute force attacks
		 */
		target = previous;
		error = aa_restore_previous_label(token);
		if (error) {
			if (error == -EACCES)
				goto kill;
			goto fail;
		}
	} /* else ignore @flags && restores when there is no saved profile */

out:
	aa_put_label(new);
	aa_put_label(previous);
	aa_put_label(label);
	put_cred(cred);

	return error;

kill:
	info = "failed token match";
	perms.kill = AA_MAY_CHANGEHAT;

fail:
	fn_for_each_in_ns(label, profile,
		aa_audit_file(profile, &perms, OP_CHANGE_HAT,
			      AA_MAY_CHANGEHAT, NULL, NULL, target,
			      GLOBAL_ROOT_UID, info, error));

	goto out;
}


static int change_profile_perms_wrapper(const char *op, const char *name,
					struct aa_profile *profile,
					struct aa_label *target, bool stack,
					u32 request, struct aa_perms *perms)
{
	const char *info = NULL;
	int error = 0;

	/*
	 * Fail explicitly requested domain transitions when no_new_privs
	 * and not unconfined OR the transition results in a stack on
	 * the current label.
	 * Stacking domain transitions and transitions from unconfined are
	 * allowed even when no_new_privs is set because this aways results
	 * in a reduction of permissions.
	 */
	if (task_no_new_privs(current) && !stack &&
	    !profile_unconfined(profile) &&
	    !aa_label_is_subset(target, &profile->label)) {
		info = "no new privs";
		error = -EPERM;
	}

	if (!error)
		error = change_profile_perms(profile, target, stack, request,
					     profile->file.start, perms);
	if (error)
		error = aa_audit_file(profile, perms, op, request, name,
				      NULL, target, GLOBAL_ROOT_UID, info,
				      error);

	return error;
}

/**
 * aa_change_profile - perform a one-way profile transition
 * @fqname: name of profile may include namespace (NOT NULL)
 * @onexec: whether this transition is to take place immediately or at exec
 * @flags: flags affecting change behavior
 *
 * Change to new profile @name.  Unlike with hats, there is no way
 * to change back.  If @name isn't specified the current profile name is
 * used.
 * If @onexec then the transition is delayed until
 * the next exec.
 *
 * Returns %0 on success, error otherwise.
 */
int aa_change_profile(const char *fqname, int flags)
{
	struct aa_label *label, *new = NULL, *target = NULL;
	struct aa_profile *profile;
	struct aa_perms perms = {};
	const char *info = NULL;
	const char *auditname = fqname;		/* retain leading & if stack */
	bool stack = flags & AA_CHANGE_STACK;
	int error = 0;
	char *op;
	u32 request;

	if (!fqname || !*fqname) {
		AA_DEBUG("no profile name");
		return -EINVAL;
	}

	if (flags & AA_CHANGE_ONEXEC) {
		request = AA_MAY_ONEXEC;
		if (stack)
			op = OP_STACK_ONEXEC;
		else
			op = OP_CHANGE_ONEXEC;
	} else {
		request = AA_MAY_CHANGE_PROFILE;
		if (stack)
			op = OP_STACK;
		else
			op = OP_CHANGE_PROFILE;
	}

	label = aa_get_current_label();

	if (*fqname == '&') {
		stack = true;
		/* don't have label_parse() do stacking */
		fqname++;
	}
	target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
	if (IS_ERR(target)) {
		struct aa_profile *tprofile;

		info = "label not found";
		error = PTR_ERR(target);
		target = NULL;
		/*
		 * TODO: fixme using labels_profile is not right - do profile
		 * per complain profile
		 */
		if ((flags & AA_CHANGE_TEST) ||
		    !COMPLAIN_MODE(labels_profile(label)))
			goto audit;
		/* released below */
		tprofile = aa_new_null_profile(labels_profile(label), false,
					       fqname, GFP_KERNEL);
		if (!tprofile) {
			info = "failed null profile create";
			error = -ENOMEM;
			goto audit;
		}
		target = &tprofile->label;
		goto check;
	}

	/*
	 * self directed transitions only apply to current policy ns
	 * TODO: currently requiring perms for stacking and straight change
	 *       stacking doesn't strictly need this. Determine how much
	 *       we want to loosen this restriction for stacking
	 *
	 * if (!stack) {
	 */
	error = fn_for_each_in_ns(label, profile,
			change_profile_perms_wrapper(op, auditname,
						     profile, target, stack,
						     request, &perms));
	if (error)
		/* auditing done in change_profile_perms_wrapper */
		goto out;

	/* } */

check:
	/* check if tracing task is allowed to trace target domain */
	error = may_change_ptraced_domain(target, &info);
	if (error && !fn_for_each_in_ns(label, profile,
					COMPLAIN_MODE(profile)))
		goto audit;

	/* TODO: add permission check to allow this
	 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
	 *      info = "not a single threaded task";
	 *      error = -EACCES;
	 *      goto audit;
	 * }
	 */
	if (flags & AA_CHANGE_TEST)
		goto out;

	if (!(flags & AA_CHANGE_ONEXEC)) {
		/* only transition profiles in the current ns */
		if (stack)
			new = aa_label_merge(label, target, GFP_KERNEL);
		else
			new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
					aa_get_label(target),
					aa_get_label(&profile->label));
		if (IS_ERR_OR_NULL(new)) {
			info = "failed to build target label";
			error = PTR_ERR(new);
			new = NULL;
			perms.allow = 0;
			goto audit;
		}
		error = aa_replace_current_label(new);
	} else
		/* full transition will be built in exec path */
		error = aa_set_current_onexec(target, stack);

audit:
	error = fn_for_each_in_ns(label, profile,
			aa_audit_file(profile, &perms, op, request, auditname,
				      NULL, new ? new : target,
				      GLOBAL_ROOT_UID, info, error));

out:
	aa_put_label(new);
	aa_put_label(target);
	aa_put_label(label);

	return error;
}
OpenPOWER on IntegriCloud