summaryrefslogtreecommitdiff
path: root/Xext/xselinux_hooks.c
blob: 13e5243c29fa8f8bc2922caeac24ad01ee579bfe (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
/************************************************************

Author: Eamon Walsh <ewalsh@tycho.nsa.gov>

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
this permission notice appear in supporting documentation.  This permission
notice shall be included in all copies or substantial portions of the
Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

********************************************************/

/*
 * Portions of this code copyright (c) 2005 by Trusted Computer Solutions, Inc.
 * All rights reserved.
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <sys/socket.h>
#include <stdio.h>
#include <stdarg.h>

#include <libaudit.h>

#include <X11/Xatom.h>
#include "selection.h"
#include "inputstr.h"
#include "scrnintstr.h"
#include "windowstr.h"
#include "propertyst.h"
#include "extnsionst.h"
#include "xacestr.h"
#include "../os/osdep.h"
#define _XSELINUX_NEED_FLASK_MAP
#include "xselinuxint.h"


/* structure passed to auditing callback */
typedef struct {
    ClientPtr client;	/* client */
    DeviceIntPtr dev;	/* device */
    char *command;	/* client's executable path */
    unsigned id;	/* resource id, if any */
    int restype;	/* resource type, if any */
    int event;		/* event type, if any */
    Atom property;	/* property name, if any */
    Atom selection;	/* selection name, if any */
    char *extension;	/* extension name, if any */
} SELinuxAuditRec;

/* private state keys */
static int subjectKeyIndex;
DevPrivateKey subjectKey = &subjectKeyIndex;
static int objectKeyIndex;
DevPrivateKey objectKey = &objectKeyIndex;
static int dataKeyIndex;
DevPrivateKey dataKey = &dataKeyIndex;

/* audit file descriptor */
static int audit_fd;

/* atoms for window label properties */
static Atom atom_ctx;
static Atom atom_client_ctx;

/* The unlabeled SID */
static security_id_t unlabeled_sid;

/* forward declarations */
static void SELinuxScreen(CallbackListPtr *, pointer, pointer);

/* "true" pointer value for use as callback data */
static pointer truep = (pointer)1;


/*
 * Performs an SELinux permission check.
 */
static int
SELinuxDoCheck(SELinuxSubjectRec *subj, SELinuxObjectRec *obj,
	       security_class_t class, Mask mode, SELinuxAuditRec *auditdata)
{
    /* serverClient requests OK */
    if (subj->privileged)
	return Success;

    auditdata->command = subj->command;
    errno = 0;

    if (avc_has_perm(subj->sid, obj->sid, class, mode, &subj->aeref,
		     auditdata) < 0) {
	if (mode == DixUnknownAccess)
	    return Success; /* DixUnknownAccess requests OK ... for now */
	if (errno == EACCES)
	    return BadAccess;
	ErrorF("SELinux: avc_has_perm: unexpected error %d\n", errno);
	return BadValue;
    }

    return Success;
}

/*
 * Labels a newly connected client.
 */
static void
SELinuxLabelClient(ClientPtr client)
{
    int fd = XaceGetConnectionNumber(client);
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    security_context_t ctx;

    subj = dixLookupPrivate(&client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&client->devPrivates, objectKey);

    /* Try to get a context from the socket */
    if (fd < 0 || getpeercon_raw(fd, &ctx) < 0) {
	/* Otherwise, fall back to a default context */
	ctx = SELinuxDefaultClientLabel();
    }

    /* For local clients, try and determine the executable name */
    if (XaceIsLocal(client)) {
	struct ucred creds;
	socklen_t len = sizeof(creds);
	char path[PATH_MAX + 1];
	size_t bytes;

	memset(&creds, 0, sizeof(creds));
	if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &creds, &len) < 0)
	    goto finish;

	snprintf(path, PATH_MAX + 1, "/proc/%d/cmdline", creds.pid);
	fd = open(path, O_RDONLY);
	if (fd < 0)
	    goto finish;

	bytes = read(fd, path, PATH_MAX + 1);
	close(fd);
	if (bytes <= 0)
	    goto finish;

	strncpy(subj->command, path, COMMAND_LEN - 1);
    }

finish:
    /* Get a SID from the context */
    if (avc_context_to_sid_raw(ctx, &subj->sid) < 0)
	FatalError("SELinux: client %d: context_to_sid_raw(%s) failed\n",
		   client->index, ctx);

    obj->sid = subj->sid;
    freecon(ctx);
}

/*
 * Labels initial server objects.
 */
static void
SELinuxLabelInitial(void)
{
    int i;
    XaceScreenAccessRec srec;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    security_context_t ctx;
    pointer unused;

    /* Do the serverClient */
    subj = dixLookupPrivate(&serverClient->devPrivates, subjectKey);
    obj = dixLookupPrivate(&serverClient->devPrivates, objectKey);
    subj->privileged = 1;

    /* Use the context of the X server process for the serverClient */
    if (getcon_raw(&ctx) < 0)
	FatalError("SELinux: couldn't get context of X server process\n");

    /* Get a SID from the context */
    if (avc_context_to_sid_raw(ctx, &subj->sid) < 0)
	FatalError("SELinux: serverClient: context_to_sid(%s) failed\n", ctx);

    obj->sid = subj->sid;
    freecon(ctx);

    srec.client = serverClient;
    srec.access_mode = DixCreateAccess;
    srec.status = Success;

    for (i = 0; i < screenInfo.numScreens; i++) {
	/* Do the screen object */
	srec.screen = screenInfo.screens[i];
	SELinuxScreen(NULL, NULL, &srec);

	/* Do the default colormap */
	dixLookupResourceByType(&unused, screenInfo.screens[i]->defColormap,
			  RT_COLORMAP, serverClient, DixCreateAccess);
    }
}

/*
 * Labels new resource objects.
 */
static int
SELinuxLabelResource(XaceResourceAccessRec *rec, SELinuxSubjectRec *subj,
		     SELinuxObjectRec *obj, security_class_t class)
{
    int offset;
    security_id_t tsid;

    /* Check for a create context */
    if (rec->rtype & RC_DRAWABLE && subj->win_create_sid) {
	obj->sid = subj->win_create_sid;
	return Success;
    }

    if (rec->parent)
	offset = dixLookupPrivateOffset(rec->ptype);

    if (rec->parent && offset >= 0) {
	/* Use the SID of the parent object in the labeling operation */
	PrivateRec **privatePtr = DEVPRIV_AT(rec->parent, offset);
	SELinuxObjectRec *pobj = dixLookupPrivate(privatePtr, objectKey);
	tsid = pobj->sid;
    } else {
	/* Use the SID of the subject */
	tsid = subj->sid;
    }

    /* Perform a transition to obtain the final SID */
    if (avc_compute_create(subj->sid, tsid, class, &obj->sid) < 0) {
	ErrorF("SELinux: a compute_create call failed!\n");
	return BadValue;
    }

    return Success;
}


/*
 * Libselinux Callbacks
 */

static int
SELinuxAudit(void *auditdata,
	     security_class_t class,
	     char *msgbuf,
	     size_t msgbufsize)
{
    SELinuxAuditRec *audit = auditdata;
    ClientPtr client = audit->client;
    char idNum[16];
    const char *propertyName, *selectionName;
    int major = -1, minor = -1;

    if (client) {
	REQUEST(xReq);
	if (stuff) {
	    major = stuff->reqType;
	    minor = MinorOpcodeOfRequest(client);
	}
    }
    if (audit->id)
	snprintf(idNum, 16, "%x", audit->id);

    propertyName = audit->property ? NameForAtom(audit->property) : NULL;
    selectionName = audit->selection ? NameForAtom(audit->selection) : NULL;

    return snprintf(msgbuf, msgbufsize,
		    "%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
		    (major >= 0) ? "request=" : "",
		    (major >= 0) ? LookupRequestName(major, minor) : "",
		    audit->command ? " comm=" : "",
		    audit->command ? audit->command : "",
		    audit->dev ? " xdevice=\"" : "",
		    audit->dev ? audit->dev->name : "",
		    audit->dev ? "\"" : "",
		    audit->id ? " resid=" : "",
		    audit->id ? idNum : "",
		    audit->restype ? " restype=" : "",
		    audit->restype ? LookupResourceName(audit->restype) : "",
		    audit->event ? " event=" : "",
		    audit->event ? LookupEventName(audit->event & 127) : "",
		    audit->property ? " property=" : "",
		    audit->property ? propertyName : "",
		    audit->selection ? " selection=" : "",
		    audit->selection ? selectionName : "",
		    audit->extension ? " extension=" : "",
		    audit->extension ? audit->extension : "");
}

static int
SELinuxLog(int type, const char *fmt, ...)
{
    va_list ap;
    char buf[MAX_AUDIT_MESSAGE_LENGTH];
    int rc, aut;

    switch (type) {
    case SELINUX_INFO:
	aut = AUDIT_USER_MAC_POLICY_LOAD;
	break;
    case SELINUX_AVC:
	aut = AUDIT_USER_AVC;
	break;
    default:
	aut = AUDIT_USER_SELINUX_ERR;
	break;
    }

    va_start(ap, fmt);
    vsnprintf(buf, MAX_AUDIT_MESSAGE_LENGTH, fmt, ap);
    rc = audit_log_user_avc_message(audit_fd, aut, buf, NULL, NULL, NULL, 0);
    va_end(ap);
    LogMessageVerb(X_WARNING, 0, "%s", buf);
    return 0;
}

/*
 * XACE Callbacks
 */

static void
SELinuxDevice(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceDeviceAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    SELinuxAuditRec auditdata = { .client = rec->client, .dev = rec->dev };
    security_class_t cls;
    int rc;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&rec->dev->devPrivates, objectKey);

    /* If this is a new object that needs labeling, do it now */
    if (rec->access_mode & DixCreateAccess) {
	SELinuxSubjectRec *dsubj;
	dsubj = dixLookupPrivate(&rec->dev->devPrivates, subjectKey);

	if (subj->dev_create_sid) {
	    /* Label the device with the create context */
	    obj->sid = subj->dev_create_sid;
	    dsubj->sid = subj->dev_create_sid;
	} else {
	    /* Label the device directly with the process SID */
	    obj->sid = subj->sid;
	    dsubj->sid = subj->sid;
	}
    }

    cls = IsPointerDevice(rec->dev) ? SECCLASS_X_POINTER : SECCLASS_X_KEYBOARD;
    rc = SELinuxDoCheck(subj, obj, cls, rec->access_mode, &auditdata);
    if (rc != Success)
	rec->status = rc;
}

static void
SELinuxSend(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceSendAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj, ev_sid;
    SELinuxAuditRec auditdata = { .client = rec->client, .dev = rec->dev };
    security_class_t class;
    int rc, i, type;

    if (rec->dev)
	subj = dixLookupPrivate(&rec->dev->devPrivates, subjectKey);
    else
	subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);

    obj = dixLookupPrivate(&rec->pWin->devPrivates, objectKey);

    /* Check send permission on window */
    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_DRAWABLE, DixSendAccess,
			&auditdata);
    if (rc != Success)
	goto err;

    /* Check send permission on specific event types */
    for (i = 0; i < rec->count; i++) {
	type = rec->events[i].u.u.type;
	class = (type & 128) ? SECCLASS_X_FAKEEVENT : SECCLASS_X_EVENT;

	rc = SELinuxEventToSID(type, obj->sid, &ev_sid);
	if (rc != Success)
	    goto err;

	auditdata.event = type;
	rc = SELinuxDoCheck(subj, &ev_sid, class, DixSendAccess, &auditdata);
	if (rc != Success)
	    goto err;
    }
    return;
err:
    rec->status = rc;
}

static void
SELinuxReceive(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceReceiveAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj, ev_sid;
    SELinuxAuditRec auditdata = { .client = NULL };
    security_class_t class;
    int rc, i, type;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&rec->pWin->devPrivates, objectKey);

    /* Check receive permission on window */
    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_DRAWABLE, DixReceiveAccess,
			&auditdata);
    if (rc != Success)
	goto err;

    /* Check receive permission on specific event types */
    for (i = 0; i < rec->count; i++) {
	type = rec->events[i].u.u.type;
	class = (type & 128) ? SECCLASS_X_FAKEEVENT : SECCLASS_X_EVENT;

	rc = SELinuxEventToSID(type, obj->sid, &ev_sid);
	if (rc != Success)
	    goto err;

	auditdata.event = type;
	rc = SELinuxDoCheck(subj, &ev_sid, class, DixReceiveAccess, &auditdata);
	if (rc != Success)
	    goto err;
    }
    return;
err:
    rec->status = rc;
}

static void
SELinuxExtension(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceExtAccessRec *rec = calldata;
    SELinuxSubjectRec *subj, *serv;
    SELinuxObjectRec *obj;
    SELinuxAuditRec auditdata = { .client = rec->client };
    int rc;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&rec->ext->devPrivates, objectKey);

    /* If this is a new object that needs labeling, do it now */
    /* XXX there should be a separate callback for this */
    if (obj->sid == NULL) {
	security_id_t sid;

	serv = dixLookupPrivate(&serverClient->devPrivates, subjectKey);
	rc = SELinuxExtensionToSID(rec->ext->name, &sid);
	if (rc != Success) {
	    rec->status = rc;
	    return;
	}

	/* Perform a transition to obtain the final SID */
	if (avc_compute_create(serv->sid, sid, SECCLASS_X_EXTENSION,
			       &obj->sid) < 0) {
	    ErrorF("SELinux: a SID transition call failed!\n");
	    rec->status = BadValue;
	    return;
	}
    }

    /* Perform the security check */
    auditdata.extension = rec->ext->name;
    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_EXTENSION, rec->access_mode,
			&auditdata);
    if (rc != Success)
	rec->status = rc;
}

static void
SELinuxSelection(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceSelectionAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj, *data;
    Selection *pSel = *rec->ppSel;
    Atom name = pSel->selection;
    Mask access_mode = rec->access_mode;
    SELinuxAuditRec auditdata = { .client = rec->client, .selection = name };
    security_id_t tsid;
    int rc;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&pSel->devPrivates, objectKey);

    /* If this is a new object that needs labeling, do it now */
    if (access_mode & DixCreateAccess) {
	rc = SELinuxSelectionToSID(name, subj, &obj->sid, &obj->poly);
	if (rc != Success)
	    obj->sid = unlabeled_sid;
	access_mode = DixSetAttrAccess;
    }
    /* If this is a polyinstantiated object, find the right instance */
    else if (obj->poly) {
	rc = SELinuxSelectionToSID(name, subj, &tsid, NULL);
	if (rc != Success) {
	    rec->status = rc;
	    return;
	}
	while (pSel->selection != name || obj->sid != tsid) {
	    if ((pSel = pSel->next) == NULL)
		break;
	    obj = dixLookupPrivate(&pSel->devPrivates, objectKey);
	}

	if (pSel)
	    *rec->ppSel = pSel;
	else {
	    rec->status = BadMatch;
	    return;
	}
    }

    /* Perform the security check */
    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_SELECTION, access_mode,
			&auditdata);
    if (rc != Success)
	rec->status = rc;

    /* Label the content (advisory only) */
    if (access_mode & DixSetAttrAccess) {
	data = dixLookupPrivate(&pSel->devPrivates, dataKey);
	if (subj->sel_create_sid)
	    data->sid = subj->sel_create_sid;
	else
	    data->sid = obj->sid;
    }
}

static void
SELinuxProperty(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XacePropertyAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj, *data;
    PropertyPtr pProp = *rec->ppProp;
    Atom name = pProp->propertyName;
    SELinuxAuditRec auditdata = { .client = rec->client, .property = name };
    security_id_t tsid;
    int rc;

    /* Don't care about the new content check */
    if (rec->access_mode & DixPostAccess)
	return;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&pProp->devPrivates, objectKey);

    /* If this is a new object that needs labeling, do it now */
    if (rec->access_mode & DixCreateAccess) {
	rc = SELinuxPropertyToSID(name, subj, &obj->sid, &obj->poly);
	if (rc != Success) {
	    rec->status = rc;
	    return;
	}
    }
    /* If this is a polyinstantiated object, find the right instance */
    else if (obj->poly) {
	rc = SELinuxPropertyToSID(name, subj, &tsid, NULL);
	if (rc != Success) {
	    rec->status = rc;
	    return;
	}
	while (pProp->propertyName != name || obj->sid != tsid) {
	    if ((pProp = pProp->next) == NULL)
		break;
	    obj = dixLookupPrivate(&pProp->devPrivates, objectKey);
	}

	if (pProp)
	    *rec->ppProp = pProp;
	else {
	    rec->status = BadMatch;
	    return;
	}
    }

    /* Perform the security check */
    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_PROPERTY, rec->access_mode,
			&auditdata);
    if (rc != Success)
	rec->status = rc;

    /* Label the content (advisory only) */
    if (rec->access_mode & DixWriteAccess) {
	data = dixLookupPrivate(&pProp->devPrivates, dataKey);
	if (subj->prp_create_sid)
	    data->sid = subj->prp_create_sid;
	else
	    data->sid = obj->sid;
    }
}

static void
SELinuxResource(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceResourceAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    SELinuxAuditRec auditdata = { .client = rec->client };
    Mask access_mode = rec->access_mode;
    PrivateRec **privatePtr;
    security_class_t class;
    int rc, offset;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);

    /* Determine if the resource object has a devPrivates field */
    offset = dixLookupPrivateOffset(rec->rtype);
    if (offset < 0) {
	/* No: use the SID of the owning client */
	class = SECCLASS_X_RESOURCE;
	privatePtr = &clients[CLIENT_ID(rec->id)]->devPrivates;
	obj = dixLookupPrivate(privatePtr, objectKey);
    } else {
	/* Yes: use the SID from the resource object itself */
	class = SELinuxTypeToClass(rec->rtype);
	privatePtr = DEVPRIV_AT(rec->res, offset);
	obj = dixLookupPrivate(privatePtr, objectKey);
    }

    /* If this is a new object that needs labeling, do it now */
    if (access_mode & DixCreateAccess && offset >= 0) {
	rc = SELinuxLabelResource(rec, subj, obj, class);
	if (rc != Success) {
	    rec->status = rc;
	    return;
	}
    }

    /* Collapse generic resource permissions down to read/write */
    if (class == SECCLASS_X_RESOURCE) {
	access_mode = !!(rec->access_mode & SELinuxReadMask); /* rd */
	access_mode |= !!(rec->access_mode & ~SELinuxReadMask) << 1; /* wr */
    }

    /* Perform the security check */
    auditdata.restype = rec->rtype;
    auditdata.id = rec->id;
    rc = SELinuxDoCheck(subj, obj, class, access_mode, &auditdata);
    if (rc != Success)
	rec->status = rc;

    /* Perform the background none check on windows */
    if (access_mode & DixCreateAccess && rec->rtype == RT_WINDOW) {
	rc = SELinuxDoCheck(subj, obj, class, DixBlendAccess, &auditdata);
	if (rc != Success)
	    ((WindowPtr)rec->res)->forcedBG = TRUE;
    }
}

static void
SELinuxScreen(CallbackListPtr *pcbl, pointer is_saver, pointer calldata)
{
    XaceScreenAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    SELinuxAuditRec auditdata = { .client = rec->client };
    Mask access_mode = rec->access_mode;
    int rc;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&rec->screen->devPrivates, objectKey);

    /* If this is a new object that needs labeling, do it now */
    if (access_mode & DixCreateAccess) {
	/* Perform a transition to obtain the final SID */
	if (avc_compute_create(subj->sid, subj->sid, SECCLASS_X_SCREEN,
			       &obj->sid) < 0) {
	    ErrorF("SELinux: a compute_create call failed!\n");
	    rec->status = BadValue;
	    return;
	}
    }

    if (is_saver)
	access_mode <<= 2;

    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_SCREEN, access_mode, &auditdata);
    if (rc != Success)
	rec->status = rc;
}

static void
SELinuxClient(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceClientAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    SELinuxAuditRec auditdata = { .client = rec->client };
    int rc;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&rec->target->devPrivates, objectKey);

    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_CLIENT, rec->access_mode,
			&auditdata);
    if (rc != Success)
	rec->status = rc;
}

static void
SELinuxServer(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    XaceServerAccessRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    SELinuxAuditRec auditdata = { .client = rec->client };
    int rc;

    subj = dixLookupPrivate(&rec->client->devPrivates, subjectKey);
    obj = dixLookupPrivate(&serverClient->devPrivates, objectKey);

    rc = SELinuxDoCheck(subj, obj, SECCLASS_X_SERVER, rec->access_mode,
			&auditdata);
    if (rc != Success)
	rec->status = rc;
}


/*
 * DIX Callbacks
 */

static void
SELinuxClientState(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    NewClientInfoRec *pci = calldata;

    switch (pci->client->clientState) {
    case ClientStateInitial:
	SELinuxLabelClient(pci->client);
	break;

    default:
	break;
    }
}

static void
SELinuxResourceState(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
    ResourceStateInfoRec *rec = calldata;
    SELinuxSubjectRec *subj;
    SELinuxObjectRec *obj;
    WindowPtr pWin;

    if (rec->type != RT_WINDOW)
	return;
    if (rec->state != ResourceStateAdding)
	return;

    pWin = (WindowPtr)rec->value;
    subj = dixLookupPrivate(&wClient(pWin)->devPrivates, subjectKey);

    if (subj->sid) {
	security_context_t ctx;
	int rc = avc_sid_to_context_raw(subj->sid, &ctx);
	if (rc < 0)
	    FatalError("SELinux: Failed to get security context!\n");
	rc = dixChangeWindowProperty(serverClient,
				     pWin, atom_client_ctx, XA_STRING, 8,
				     PropModeReplace, strlen(ctx), ctx, FALSE);
	if (rc != Success)
	    FatalError("SELinux: Failed to set label property on window!\n");
	freecon(ctx);
    } else
	FatalError("SELinux: Unexpected unlabeled client found\n");

    obj = dixLookupPrivate(&pWin->devPrivates, objectKey);

    if (obj->sid) {
	security_context_t ctx;
	int rc = avc_sid_to_context_raw(obj->sid, &ctx);
	if (rc < 0)
	    FatalError("SELinux: Failed to get security context!\n");
	rc = dixChangeWindowProperty(serverClient,
				     pWin, atom_ctx, XA_STRING, 8,
				     PropModeReplace, strlen(ctx), ctx, FALSE);
	if (rc != Success)
	    FatalError("SELinux: Failed to set label property on window!\n");
	freecon(ctx);
    } else
	FatalError("SELinux: Unexpected unlabeled window found\n");
}


static int netlink_fd;

static void
SELinuxBlockHandler(void *data, struct timeval **tv, void *read_mask)
{
}

static void
SELinuxWakeupHandler(void *data, int err, void *read_mask)
{
    if (FD_ISSET(netlink_fd, (fd_set *)read_mask))
        avc_netlink_check_nb();
}

void
SELinuxFlaskReset(void)
{
    /* Unregister callbacks */
    DeleteCallback(&ClientStateCallback, SELinuxClientState, NULL);
    DeleteCallback(&ResourceStateCallback, SELinuxResourceState, NULL);

    XaceDeleteCallback(XACE_EXT_DISPATCH, SELinuxExtension, NULL);
    XaceDeleteCallback(XACE_RESOURCE_ACCESS, SELinuxResource, NULL);
    XaceDeleteCallback(XACE_DEVICE_ACCESS, SELinuxDevice, NULL);
    XaceDeleteCallback(XACE_PROPERTY_ACCESS, SELinuxProperty, NULL);
    XaceDeleteCallback(XACE_SEND_ACCESS, SELinuxSend, NULL);
    XaceDeleteCallback(XACE_RECEIVE_ACCESS, SELinuxReceive, NULL);
    XaceDeleteCallback(XACE_CLIENT_ACCESS, SELinuxClient, NULL);
    XaceDeleteCallback(XACE_EXT_ACCESS, SELinuxExtension, NULL);
    XaceDeleteCallback(XACE_SERVER_ACCESS, SELinuxServer, NULL);
    XaceDeleteCallback(XACE_SELECTION_ACCESS, SELinuxSelection, NULL);
    XaceDeleteCallback(XACE_SCREEN_ACCESS, SELinuxScreen, NULL);
    XaceDeleteCallback(XACE_SCREENSAVER_ACCESS, SELinuxScreen, truep);

    /* Tear down SELinux stuff */
    audit_close(audit_fd);
    avc_netlink_release_fd();
    RemoveBlockAndWakeupHandlers(SELinuxBlockHandler, SELinuxWakeupHandler,
                                 NULL);
    RemoveGeneralSocket(netlink_fd);

    avc_destroy();
}

void
SELinuxFlaskInit(void)
{
    struct selinux_opt avc_option = { AVC_OPT_SETENFORCE, (char *)0 };
    security_context_t ctx;
    int ret = TRUE;

    switch(selinuxEnforcingState) {
    case SELINUX_MODE_ENFORCING:
	LogMessage(X_INFO, "SELinux: Configured in enforcing mode\n");
	avc_option.value = (char *)1;
	break;
    case SELINUX_MODE_PERMISSIVE:
	LogMessage(X_INFO, "SELinux: Configured in permissive mode\n");
	avc_option.value = (char *)0;
	break;
    default:
	avc_option.type = AVC_OPT_UNUSED;
	break;
    }

    /* Set up SELinux stuff */
    selinux_set_callback(SELINUX_CB_LOG, (union selinux_callback)SELinuxLog);
    selinux_set_callback(SELINUX_CB_AUDIT, (union selinux_callback)SELinuxAudit);

    if (selinux_set_mapping(map) < 0) {
	if (errno == EINVAL) {
	    ErrorF("SELinux: Invalid object class mapping, disabling SELinux support.\n");
	    return;
	}
	FatalError("SELinux: Failed to set up security class mapping\n");
    }

    if (avc_open(&avc_option, 1) < 0)
	FatalError("SELinux: Couldn't initialize SELinux userspace AVC\n");

    if (security_get_initial_context_raw("unlabeled", &ctx) < 0)
	FatalError("SELinux: Failed to look up unlabeled context\n");
    if (avc_context_to_sid_raw(ctx, &unlabeled_sid) < 0)
	FatalError("SELinux: a context_to_SID call failed!\n");
    freecon(ctx);

    /* Prepare for auditing */
    audit_fd = audit_open();
    if (audit_fd < 0)
	FatalError("SELinux: Failed to open the system audit log\n");

    /* Allocate private storage */
    if (!dixRequestPrivate(subjectKey, sizeof(SELinuxSubjectRec)) ||
	!dixRequestPrivate(objectKey, sizeof(SELinuxObjectRec)) ||
	!dixRequestPrivate(dataKey, sizeof(SELinuxObjectRec)))
	FatalError("SELinux: Failed to allocate private storage.\n");

    /* Create atoms for doing window labeling */
    atom_ctx = MakeAtom("_SELINUX_CONTEXT", 16, TRUE);
    if (atom_ctx == BAD_RESOURCE)
	FatalError("SELinux: Failed to create atom\n");
    atom_client_ctx = MakeAtom("_SELINUX_CLIENT_CONTEXT", 23, TRUE);
    if (atom_client_ctx == BAD_RESOURCE)
	FatalError("SELinux: Failed to create atom\n");

    netlink_fd = avc_netlink_acquire_fd();
    AddGeneralSocket(netlink_fd);
    RegisterBlockAndWakeupHandlers(SELinuxBlockHandler, SELinuxWakeupHandler,
                                   NULL);

    /* Register callbacks */
    ret &= AddCallback(&ClientStateCallback, SELinuxClientState, NULL);
    ret &= AddCallback(&ResourceStateCallback, SELinuxResourceState, NULL);

    ret &= XaceRegisterCallback(XACE_EXT_DISPATCH, SELinuxExtension, NULL);
    ret &= XaceRegisterCallback(XACE_RESOURCE_ACCESS, SELinuxResource, NULL);
    ret &= XaceRegisterCallback(XACE_DEVICE_ACCESS, SELinuxDevice, NULL);
    ret &= XaceRegisterCallback(XACE_PROPERTY_ACCESS, SELinuxProperty, NULL);
    ret &= XaceRegisterCallback(XACE_SEND_ACCESS, SELinuxSend, NULL);
    ret &= XaceRegisterCallback(XACE_RECEIVE_ACCESS, SELinuxReceive, NULL);
    ret &= XaceRegisterCallback(XACE_CLIENT_ACCESS, SELinuxClient, NULL);
    ret &= XaceRegisterCallback(XACE_EXT_ACCESS, SELinuxExtension, NULL);
    ret &= XaceRegisterCallback(XACE_SERVER_ACCESS, SELinuxServer, NULL);
    ret &= XaceRegisterCallback(XACE_SELECTION_ACCESS, SELinuxSelection, NULL);
    ret &= XaceRegisterCallback(XACE_SCREEN_ACCESS, SELinuxScreen, NULL);
    ret &= XaceRegisterCallback(XACE_SCREENSAVER_ACCESS, SELinuxScreen, truep);
    if (!ret)
	FatalError("SELinux: Failed to register one or more callbacks\n");

    /* Label objects that were created before we could register ourself */
    SELinuxLabelInitial();
}