summaryrefslogtreecommitdiffstats
path: root/sys/kern/kern_exec.c
blob: 7f5c81938d990278db3d5b780ab371ce29dee15c (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
/*
 * Copyright (c) 1993, David Greenman
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#include "opt_ktrace.h"
#include "opt_mac.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/mac.h>
#include <sys/mount.h>
#include <sys/filedesc.h>
#include <sys/fcntl.h>
#include <sys/acct.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/wait.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/pioctl.h>
#include <sys/namei.h>
#include <sys/sysent.h>
#include <sys/shm.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <sys/vnode.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>

#include <machine/reg.h>

MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");

static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
static int kern_execve(struct thread *td, char *fname, char **argv,
	char **envv, struct mac *mac_p);

/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
    NULL, 0, sysctl_kern_ps_strings, "LU", "");

/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD,
    NULL, 0, sysctl_kern_usrstack, "LU", "");

SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
    NULL, 0, sysctl_kern_stackprot, "I", "");

u_long ps_arg_cache_limit = PAGE_SIZE / 16;
SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
    &ps_arg_cache_limit, 0, "");

int ps_argsopen = 1;
SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, "");

#ifdef __ia64__
/* XXX HACK */
static int regstkpages = 256;
SYSCTL_INT(_machdep, OID_AUTO, regstkpages, CTLFLAG_RW, &regstkpages, 0, "");
#endif

static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
{
	struct proc *p;

	p = curproc;
	return (SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
	   sizeof(p->p_sysent->sv_psstrings)));
}

static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
{
	struct proc *p;

	p = curproc;
	return (SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
	    sizeof(p->p_sysent->sv_usrstack)));
}

static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
{
	struct proc *p;

	p = curproc;
	return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
	    sizeof(p->p_sysent->sv_stackprot)));
}

/*
 * Each of the items is a pointer to a `const struct execsw', hence the
 * double pointer here.
 */
static const struct execsw **execsw;

/*
 * In-kernel implementation of execve().  All arguments are assumed to be
 * userspace pointers from the passed thread.
 *
 * MPSAFE
 */
static int
kern_execve(td, fname, argv, envv, mac_p)
	struct thread *td;
	char *fname;
	char **argv;
	char **envv;
	struct mac *mac_p;
{
	struct proc *p = td->td_proc;
	struct nameidata nd, *ndp;
	struct ucred *newcred = NULL, *oldcred;
	struct uidinfo *euip;
	register_t *stack_base;
	int error, len, i;
	struct image_params image_params, *imgp;
	struct vattr attr;
	int (*img_first)(struct image_params *);
	struct pargs *oldargs = NULL, *newargs = NULL;
	struct procsig *oldprocsig, *newprocsig;
#ifdef KTRACE
	struct vnode *tracevp = NULL;
	struct ucred *tracecred = NULL;
#endif
	struct vnode *textvp = NULL;
	int credential_changing;
	int textset;
#ifdef MAC
	struct label interplabel;	/* label of the interpreted vnode */
	struct label execlabel;		/* optional label argument */
	int will_transition, interplabelvalid = 0;
#endif

	imgp = &image_params;

	/*
	 * Lock the process and set the P_INEXEC flag to indicate that
	 * it should be left alone until we're done here.  This is
	 * necessary to avoid race conditions - e.g. in ptrace() -
	 * that might allow a local user to illicitly obtain elevated
	 * privileges.
	 */
	PROC_LOCK(p);
	KASSERT((p->p_flag & P_INEXEC) == 0,
	    ("%s(): process already has P_INEXEC flag", __func__));
	if (p->p_flag & P_THREADED || p->p_numthreads > 1) {
		if (thread_single(SINGLE_EXIT)) {
			PROC_UNLOCK(p);
			return (ERESTART);	/* Try again later. */
		}
		/*
		 * If we get here all other threads are dead,
		 * so unset the associated flags and lose KSE mode.
		 */
		p->p_flag &= ~P_THREADED;
		td->td_mailbox = NULL;
		thread_single_end();
	}
	p->p_flag |= P_INEXEC;
	PROC_UNLOCK(p);

	/*
	 * Initialize part of the common data
	 */
	imgp->proc = p;
	imgp->userspace_argv = argv;
	imgp->userspace_envv = envv;
	imgp->execlabel = NULL;
	imgp->attr = &attr;
	imgp->argc = imgp->envc = 0;
	imgp->argv0 = NULL;
	imgp->entry_addr = 0;
	imgp->vmspace_destroyed = 0;
	imgp->interpreted = 0;
	imgp->interpreter_name[0] = '\0';
	imgp->auxargs = NULL;
	imgp->vp = NULL;
	imgp->object = NULL;
	imgp->firstpage = NULL;
	imgp->ps_strings = 0;
	imgp->auxarg_size = 0;

#ifdef MAC
	error = mac_execve_enter(imgp, mac_p, &execlabel);
	if (error) {
		mtx_lock(&Giant);
		goto exec_fail;
	}
#endif

	/*
	 * Allocate temporary demand zeroed space for argument and
	 *	environment strings
	 */
	imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX +
	    PAGE_SIZE);
	if (imgp->stringbase == NULL) {
		error = ENOMEM;
		mtx_lock(&Giant);
		goto exec_fail;
	}
	imgp->stringp = imgp->stringbase;
	imgp->stringspace = ARG_MAX;
	imgp->image_header = imgp->stringbase + ARG_MAX;

	/*
	 * Translate the file name. namei() returns a vnode pointer
	 *	in ni_vp amoung other things.
	 */
	ndp = &nd;
	NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
	    UIO_USERSPACE, fname, td);

	mtx_lock(&Giant);
interpret:

	error = namei(ndp);
	if (error) {
		kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
		    ARG_MAX + PAGE_SIZE);
		goto exec_fail;
	}

	imgp->vp = ndp->ni_vp;
	imgp->fname = fname;

	/*
	 * Check file permissions (also 'opens' file)
	 */
	error = exec_check_permissions(imgp);
	if (error)
		goto exec_fail_dealloc;

	if (VOP_GETVOBJECT(imgp->vp, &imgp->object) == 0)
		vm_object_reference(imgp->object);

	/*
	 * Set VV_TEXT now so no one can write to the executable while we're
	 * activating it.
	 *
	 * Remember if this was set before and unset it in case this is not
	 * actually an executable image.
	 */
	textset = imgp->vp->v_vflag & VV_TEXT;
	imgp->vp->v_vflag |= VV_TEXT;

	error = exec_map_first_page(imgp);
	if (error)
		goto exec_fail_dealloc;

	/*
	 *	If the current process has a special image activator it
	 *	wants to try first, call it.   For example, emulating shell 
	 *	scripts differently.
	 */
	error = -1;
	if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
		error = img_first(imgp);

	/*
	 *	Loop through the list of image activators, calling each one.
	 *	An activator returns -1 if there is no match, 0 on success,
	 *	and an error otherwise.
	 */
	for (i = 0; error == -1 && execsw[i]; ++i) {
		if (execsw[i]->ex_imgact == NULL ||
		    execsw[i]->ex_imgact == img_first) {
			continue;
		}
		error = (*execsw[i]->ex_imgact)(imgp);
	}

	if (error) {
		if (error == -1) {
			if (textset == 0)
				imgp->vp->v_vflag &= ~VV_TEXT;
			error = ENOEXEC;
		}
		goto exec_fail_dealloc;
	}

	/*
	 * Special interpreter operation, cleanup and loop up to try to
	 * activate the interpreter.
	 */
	if (imgp->interpreted) {
		exec_unmap_first_page(imgp);
		/*
		 * VV_TEXT needs to be unset for scripts.  There is a short
		 * period before we determine that something is a script where
		 * VV_TEXT will be set. The vnode lock is held over this
		 * entire period so nothing should illegitimately be blocked.
		 */
		imgp->vp->v_vflag &= ~VV_TEXT;
		/* free name buffer and old vnode */
		NDFREE(ndp, NDF_ONLY_PNBUF);
#ifdef MAC
		mac_init_vnode_label(&interplabel);
		mac_copy_vnode_label(&ndp->ni_vp->v_label, &interplabel);
		interplabelvalid = 1;
#endif
		vput(ndp->ni_vp);
		vm_object_deallocate(imgp->object);
		imgp->object = NULL;
		/* set new name to that of the interpreter */
		NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
		    UIO_SYSSPACE, imgp->interpreter_name, td);
		goto interpret;
	}

	/*
	 * Copy out strings (args and env) and initialize stack base
	 */
	if (p->p_sysent->sv_copyout_strings)
		stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
	else
		stack_base = exec_copyout_strings(imgp);

	/*
	 * If custom stack fixup routine present for this process
	 * let it do the stack setup.
	 * Else stuff argument count as first item on stack
	 */
	if (p->p_sysent->sv_fixup)
		(*p->p_sysent->sv_fixup)(&stack_base, imgp);
	else
		suword(--stack_base, imgp->argc);

	/*
	 * For security and other reasons, the file descriptor table cannot
	 * be shared after an exec.
	 */
	FILEDESC_LOCK(p->p_fd);
	if (p->p_fd->fd_refcnt > 1) {
		struct filedesc *tmp;

		tmp = fdcopy(td->td_proc->p_fd);
		FILEDESC_UNLOCK(p->p_fd);
		fdfree(td);
		p->p_fd = tmp;
	} else
		FILEDESC_UNLOCK(p->p_fd);

	/*
	 * Malloc things before we need locks.
	 */
	newcred = crget();
	euip = uifind(attr.va_uid);
	i = imgp->endargs - imgp->stringbase;
	if (ps_arg_cache_limit >= i + sizeof(struct pargs))
		newargs = pargs_alloc(i);

	/* close files on exec */
	fdcloseexec(td);

	/* Get a reference to the vnode prior to locking the proc */
	VREF(ndp->ni_vp);

	/*
	 * For security and other reasons, signal handlers cannot
	 * be shared after an exec. The new process gets a copy of the old
	 * handlers. In execsigs(), the new process will have its signals
	 * reset.
	 */
	PROC_LOCK(p);
	mp_fixme("procsig needs a lock");
	if (p->p_procsig->ps_refcnt > 1) {
		oldprocsig = p->p_procsig;
		PROC_UNLOCK(p);
		MALLOC(newprocsig, struct procsig *, sizeof(struct procsig),
		    M_SUBPROC, M_WAITOK);
		bcopy(oldprocsig, newprocsig, sizeof(*newprocsig));
		newprocsig->ps_refcnt = 1;
		oldprocsig->ps_refcnt--;
		PROC_LOCK(p);
		p->p_procsig = newprocsig;
		if (p->p_sigacts == &p->p_uarea->u_sigacts)
			panic("shared procsig but private sigacts?");

		p->p_uarea->u_sigacts = *p->p_sigacts;
		p->p_sigacts = &p->p_uarea->u_sigacts;
	}
	/* Stop profiling */
	stopprofclock(p);

	/* reset caught signals */
	execsigs(p);

	/* name this process - nameiexec(p, ndp) */
	len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN);
	bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len);
	p->p_comm[len] = 0;

	/*
	 * mark as execed, wakeup the process that vforked (if any) and tell
	 * it that it now has its own resources back
	 */
	p->p_flag |= P_EXEC;
	if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
		p->p_flag &= ~P_PPWAIT;
		wakeup(p->p_pptr);
	}

	/*
	 * Implement image setuid/setgid.
	 *
	 * Don't honor setuid/setgid if the filesystem prohibits it or if
	 * the process is being traced.
	 *
	 * XXXMAC: For the time being, use NOSUID to also prohibit
	 * transitions on the file system.
	 */
	oldcred = p->p_ucred;
	credential_changing = 0;
	credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid !=
	    attr.va_uid;
	credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid !=
	    attr.va_gid;
#ifdef MAC
	will_transition = mac_execve_will_transition(oldcred, imgp->vp,
	    interplabelvalid ? &interplabel : NULL, imgp);
	credential_changing |= will_transition;
#endif

	if (credential_changing &&
	    (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
	    (p->p_flag & P_TRACED) == 0) {
		/*
		 * Turn off syscall tracing for set-id programs, except for
		 * root.  Record any set-id flags first to make sure that
		 * we do not regain any tracing during a possible block.
		 */
		setsugid(p);
#ifdef KTRACE
		if (p->p_tracevp != NULL && suser_cred(oldcred, PRISON_ROOT)) {
			mtx_lock(&ktrace_mtx);
			p->p_traceflag = 0;
			tracevp = p->p_tracevp;
			p->p_tracevp = NULL;
			tracecred = p->p_tracecred;
			p->p_tracecred = NULL;
			mtx_unlock(&ktrace_mtx);
		}
#endif
		/*
		 * Close any file descriptors 0..2 that reference procfs,
		 * then make sure file descriptors 0..2 are in use.
		 *
		 * setugidsafety() may call closef() and then pfind()
		 * which may grab the process lock.
		 * fdcheckstd() may call falloc() which may block to
		 * allocate memory, so temporarily drop the process lock.
		 */
		PROC_UNLOCK(p);
		setugidsafety(td);
		error = fdcheckstd(td);
		if (error != 0)
			goto done1;
		PROC_LOCK(p);
		/*
		 * Set the new credentials.
		 */
		crcopy(newcred, oldcred);
		if (attr.va_mode & VSUID)
			change_euid(newcred, euip);
		if (attr.va_mode & VSGID)
			change_egid(newcred, attr.va_gid);
#ifdef MAC
		if (will_transition) {
			mac_execve_transition(oldcred, newcred, imgp->vp,
			    interplabelvalid ? &interplabel : NULL, imgp);
		}
#endif
		/*
		 * Implement correct POSIX saved-id behavior.
		 *
		 * XXXMAC: Note that the current logic will save the
		 * uid and gid if a MAC domain transition occurs, even
		 * though maybe it shouldn't.
		 */
		change_svuid(newcred, newcred->cr_uid);
		change_svgid(newcred, newcred->cr_gid);
		p->p_ucred = newcred;
		newcred = NULL;
	} else {
		if (oldcred->cr_uid == oldcred->cr_ruid &&
		    oldcred->cr_gid == oldcred->cr_rgid)
			p->p_flag &= ~P_SUGID;
		/*
		 * Implement correct POSIX saved-id behavior.
		 *
		 * XXX: It's not clear that the existing behavior is
		 * POSIX-compliant.  A number of sources indicate that the
		 * saved uid/gid should only be updated if the new ruid is
		 * not equal to the old ruid, or the new euid is not equal
		 * to the old euid and the new euid is not equal to the old
		 * ruid.  The FreeBSD code always updates the saved uid/gid.
		 * Also, this code uses the new (replaced) euid and egid as
		 * the source, which may or may not be the right ones to use.
		 */
		if (oldcred->cr_svuid != oldcred->cr_uid ||
		    oldcred->cr_svgid != oldcred->cr_gid) {
			crcopy(newcred, oldcred);
			change_svuid(newcred, newcred->cr_uid);
			change_svgid(newcred, newcred->cr_gid);
			p->p_ucred = newcred;
			newcred = NULL;
		}
	}

	/*
	 * Store the vp for use in procfs.  This vnode was referenced prior
	 * to locking the proc lock.
	 */
	textvp = p->p_textvp;
	p->p_textvp = ndp->ni_vp;

	/*
	 * Notify others that we exec'd, and clear the P_INEXEC flag
	 * as we're now a bona fide freshly-execed process.
	 */
	KNOTE(&p->p_klist, NOTE_EXEC);
	p->p_flag &= ~P_INEXEC;

	/*
	 * If tracing the process, trap to debugger so breakpoints
	 * can be set before the program executes.
	 */
	if (p->p_flag & P_TRACED)
		psignal(p, SIGTRAP);

	/* clear "fork but no exec" flag, as we _are_ execing */
	p->p_acflag &= ~AFORK;

	/* Free any previous argument cache */
	oldargs = p->p_args;
	p->p_args = NULL;

	/* Cache arguments if they fit inside our allowance */
	if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
		bcopy(imgp->stringbase, newargs->ar_args, i);
		p->p_args = newargs;
		newargs = NULL;
	}
	PROC_UNLOCK(p);

	/* Set values passed into the program in registers. */
	if (p->p_sysent->sv_setregs)
		(*p->p_sysent->sv_setregs)(td, imgp->entry_addr,
		    (u_long)(uintptr_t)stack_base, imgp->ps_strings);
	else
		exec_setregs(td, imgp->entry_addr,
		    (u_long)(uintptr_t)stack_base, imgp->ps_strings);

done1:
	/*
	 * Free any resources malloc'd earlier that we didn't use.
	 */
	uifree(euip);
	if (newcred == NULL)
		crfree(oldcred);
	else
		crfree(newcred);
	/*
	 * Handle deferred decrement of ref counts.
	 */
	if (textvp != NULL)
		vrele(textvp);
	if (ndp->ni_vp && error != 0)
		vrele(ndp->ni_vp);
#ifdef KTRACE
	if (tracevp != NULL)
		vrele(tracevp);
	if (tracecred != NULL)
		crfree(tracecred);
#endif
	if (oldargs != NULL)
		pargs_drop(oldargs);
	if (newargs != NULL)
		pargs_drop(newargs);

exec_fail_dealloc:

	/*
	 * free various allocated resources
	 */
	if (imgp->firstpage)
		exec_unmap_first_page(imgp);

	if (imgp->vp) {
		NDFREE(ndp, NDF_ONLY_PNBUF);
		vput(imgp->vp);
	}

	if (imgp->stringbase != NULL)
		kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
		    ARG_MAX + PAGE_SIZE);

	if (imgp->object)
		vm_object_deallocate(imgp->object);

	if (error == 0) {
		/*
		 * Stop the process here if its stop event mask has
		 * the S_EXEC bit set.
		 */
		STOPEVENT(p, S_EXEC, 0);
		goto done2;
	}

exec_fail:
	/* we're done here, clear P_INEXEC */
	PROC_LOCK(p);
	p->p_flag &= ~P_INEXEC;
	PROC_UNLOCK(p);
	
	if (imgp->vmspace_destroyed) {
		/* sorry, no more process anymore. exit gracefully */
#ifdef MAC
		mac_execve_exit(imgp);
		if (interplabelvalid)
			mac_destroy_vnode_label(&interplabel);
#endif
		exit1(td, W_EXITCODE(0, SIGABRT));
		/* NOT REACHED */
		error = 0;
	}
done2:
#ifdef MAC
	mac_execve_exit(imgp);
	if (interplabelvalid)
		mac_destroy_vnode_label(&interplabel);
#endif
	mtx_unlock(&Giant);
	return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct execve_args {
        char    *fname; 
        char    **argv;
        char    **envv; 
};
#endif

/*
 * MPSAFE
 */
int
execve(td, uap)
	struct thread *td;
	struct execve_args /* {
		char *fname;
		char **argv;
		char **envv;
	} */ *uap;
{

	return (kern_execve(td, uap->fname, uap->argv, uap->envv, NULL));
}

#ifndef _SYS_SYSPROTO_H_
struct __mac_execve_args {
	char	*fname;
	char	**argv;
	char	**envv;
	struct mac	*mac_p;
};
#endif

/*
 * MPSAFE
 */
int
__mac_execve(td, uap)
	struct thread *td;
	struct __mac_execve_args /* {
		char *fname;
		char **argv;
		char **envv;
		struct mac *mac_p;
	} */ *uap;
{

#ifdef MAC
	return (kern_execve(td, uap->fname, uap->argv, uap->envv,
	    uap->mac_p));
#else
	return (ENOSYS);
#endif
}

int
exec_map_first_page(imgp)
	struct image_params *imgp;
{
	int rv, i;
	int initial_pagein;
	vm_page_t ma[VM_INITIAL_PAGEIN];
	vm_object_t object;

	GIANT_REQUIRED;

	if (imgp->firstpage) {
		exec_unmap_first_page(imgp);
	}

	VOP_GETVOBJECT(imgp->vp, &object);

	ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);

	if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
		initial_pagein = VM_INITIAL_PAGEIN;
		if (initial_pagein > object->size)
			initial_pagein = object->size;
		for (i = 1; i < initial_pagein; i++) {
			if ((ma[i] = vm_page_lookup(object, i)) != NULL) {
				if ((ma[i]->flags & PG_BUSY) || ma[i]->busy)
					break;
				if (ma[i]->valid)
					break;
				vm_page_lock_queues();
				vm_page_busy(ma[i]);
				vm_page_unlock_queues();
			} else {
				ma[i] = vm_page_alloc(object, i,
				    VM_ALLOC_NORMAL);
				if (ma[i] == NULL)
					break;
			}
		}
		initial_pagein = i;

		rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
		ma[0] = vm_page_lookup(object, 0);

		if ((rv != VM_PAGER_OK) || (ma[0] == NULL) ||
		    (ma[0]->valid == 0)) {
			if (ma[0]) {
				vm_page_lock_queues();
				pmap_remove_all(ma[0]);
				vm_page_free(ma[0]);
				vm_page_unlock_queues();
			}
			return (EIO);
		}
	}
	vm_page_lock_queues();
	vm_page_wire(ma[0]);
	vm_page_wakeup(ma[0]);
	vm_page_unlock_queues();

	pmap_qenter((vm_offset_t)imgp->image_header, ma, 1);
	imgp->firstpage = ma[0];

	return (0);
}

void
exec_unmap_first_page(imgp)
	struct image_params *imgp;
{
	GIANT_REQUIRED;

	if (imgp->firstpage) {
		pmap_qremove((vm_offset_t)imgp->image_header, 1);
		vm_page_lock_queues();
		vm_page_unwire(imgp->firstpage, 1);
		vm_page_unlock_queues();
		imgp->firstpage = NULL;
	}
}

/*
 * Destroy old address space, and allocate a new stack
 *	The new stack is only SGROWSIZ large because it is grown
 *	automatically in trap.c.
 */
int
exec_new_vmspace(imgp, sv)
	struct image_params *imgp;
	struct sysentvec *sv;
{
	int error;
	struct proc *p = imgp->proc;
	struct vmspace *vmspace = p->p_vmspace;
	vm_offset_t stack_addr;
	vm_map_t map;

	GIANT_REQUIRED;

	stack_addr = sv->sv_usrstack - maxssiz;

	imgp->vmspace_destroyed = 1;

	EVENTHANDLER_INVOKE(process_exec, p);

	/*
	 * Blow away entire process VM, if address space not shared,
	 * otherwise, create a new VM space so that other threads are
	 * not disrupted
	 */
	map = &vmspace->vm_map;
	if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser &&
	    vm_map_max(map) == sv->sv_maxuser) {
		shmexit(vmspace);
		vm_page_lock_queues();
		pmap_remove_pages(vmspace_pmap(vmspace), vm_map_min(map),
		    vm_map_max(map));
		vm_page_unlock_queues();
		vm_map_remove(map, vm_map_min(map), vm_map_max(map));
	} else {
		vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
		vmspace = p->p_vmspace;
		map = &vmspace->vm_map;
	}

	/* Allocate a new stack */
	error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz,
	    sv->sv_stackprot, VM_PROT_ALL, 0);
	if (error)
		return (error);

#ifdef __ia64__
	{
		/*
		 * Allocate backing store. We really need something
		 * similar to vm_map_stack which can allow the backing 
		 * store to grow upwards. This will do for now.
		 */
		vm_offset_t bsaddr;
		bsaddr = p->p_sysent->sv_usrstack - 2 * maxssiz;
		error = vm_map_find(map, 0, 0, &bsaddr,
		    regstkpages * PAGE_SIZE, 0, VM_PROT_ALL, VM_PROT_ALL, 0);
		FIRST_THREAD_IN_PROC(p)->td_md.md_bspstore = bsaddr;
	}
#endif

	/* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
	 * VM_STACK case, but they are still used to monitor the size of the
	 * process stack so we can check the stack rlimit.
	 */
	vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
	vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - maxssiz;

	return (0);
}

/*
 * Copy out argument and environment strings from the old process
 *	address space into the temporary string buffer.
 */
int
exec_extract_strings(imgp)
	struct image_params *imgp;
{
	char	**argv, **envv;
	char	*argp, *envp;
	int	error;
	size_t	length;

	/*
	 * extract arguments first
	 */

	argv = imgp->userspace_argv;

	if (argv) {
		argp = (caddr_t)(intptr_t)fuword(argv);
		if (argp == (caddr_t)-1)
			return (EFAULT);
		if (argp)
			argv++;
		if (imgp->argv0)
			argp = imgp->argv0;
		if (argp) {
			do {
				if (argp == (caddr_t)-1)
					return (EFAULT);
				if ((error = copyinstr(argp, imgp->stringp,
				    imgp->stringspace, &length))) {
					if (error == ENAMETOOLONG)
						return (E2BIG);
					return (error);
				}
				imgp->stringspace -= length;
				imgp->stringp += length;
				imgp->argc++;
			} while ((argp = (caddr_t)(intptr_t)fuword(argv++)));
		}
	}	

	imgp->endargs = imgp->stringp;

	/*
	 * extract environment strings
	 */

	envv = imgp->userspace_envv;

	if (envv) {
		while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
			if (envp == (caddr_t)-1)
				return (EFAULT);
			if ((error = copyinstr(envp, imgp->stringp,
			    imgp->stringspace, &length))) {
				if (error == ENAMETOOLONG)
					return (E2BIG);
				return (error);
			}
			imgp->stringspace -= length;
			imgp->stringp += length;
			imgp->envc++;
		}
	}

	return (0);
}

/*
 * Copy strings out to the new process address space, constructing
 *	new arg and env vector tables. Return a pointer to the base
 *	so that it can be used as the initial stack pointer.
 */
register_t *
exec_copyout_strings(imgp)
	struct image_params *imgp;
{
	int argc, envc;
	char **vectp;
	char *stringp, *destp;
	register_t *stack_base;
	struct ps_strings *arginfo;
	struct proc *p;
	int szsigcode;

	/*
	 * Calculate string base and vector table pointers.
	 * Also deal with signal trampoline code for this exec type.
	 */
	p = imgp->proc;
	szsigcode = 0;
	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
	if (p->p_sysent->sv_szsigcode != NULL)
		szsigcode = *(p->p_sysent->sv_szsigcode);
	destp =	(caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
	    roundup((ARG_MAX - imgp->stringspace), sizeof(char *));

	/*
	 * install sigcode
	 */
	if (szsigcode)
		copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo -
		    szsigcode), szsigcode);

	/*
	 * If we have a valid auxargs ptr, prepare some room
	 * on the stack.
	 */
	if (imgp->auxargs) {
		/*
		 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
		 * lower compatibility.
		 */
		imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
		    (AT_COUNT * 2);
		/*
		 * The '+ 2' is for the null pointers at the end of each of
		 * the arg and env vector sets,and imgp->auxarg_size is room
		 * for argument of Runtime loader.
		 */
		vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 +
		    imgp->auxarg_size) * sizeof(char *));

	} else 
		/*
		 * The '+ 2' is for the null pointers at the end of each of
		 * the arg and env vector sets
		 */
		vectp = (char **)(destp - (imgp->argc + imgp->envc + 2) *
		    sizeof(char *));

	/*
	 * vectp also becomes our initial stack base
	 */
	stack_base = (register_t *)vectp;

	stringp = imgp->stringbase;
	argc = imgp->argc;
	envc = imgp->envc;

	/*
	 * Copy out strings - arguments and environment.
	 */
	copyout(stringp, destp, ARG_MAX - imgp->stringspace);

	/*
	 * Fill in "ps_strings" struct for ps, w, etc.
	 */
	suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
	suword(&arginfo->ps_nargvstr, argc);

	/*
	 * Fill in argument portion of vector table.
	 */
	for (; argc > 0; --argc) {
		suword(vectp++, (long)(intptr_t)destp);
		while (*stringp++ != 0)
			destp++;
		destp++;
	}

	/* a null vector table pointer separates the argp's from the envp's */
	suword(vectp++, 0);

	suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
	suword(&arginfo->ps_nenvstr, envc);

	/*
	 * Fill in environment portion of vector table.
	 */
	for (; envc > 0; --envc) {
		suword(vectp++, (long)(intptr_t)destp);
		while (*stringp++ != 0)
			destp++;
		destp++;
	}

	/* end of vector table is a null pointer */
	suword(vectp, 0);

	return (stack_base);
}

/*
 * Check permissions of file to execute.
 *	Called with imgp->vp locked.
 *	Return 0 for success or error code on failure.
 */
int
exec_check_permissions(imgp)
	struct image_params *imgp;
{
	struct vnode *vp = imgp->vp;
	struct vattr *attr = imgp->attr;
	struct thread *td;
	int error;

	td = curthread;			/* XXXKSE */

	/* Get file attributes */
	error = VOP_GETATTR(vp, attr, td->td_ucred, td);
	if (error)
		return (error);

#ifdef MAC
	error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp);
	if (error)
		return (error);
#endif
	
	/*
	 * 1) Check if file execution is disabled for the filesystem that this
	 *	file resides on.
	 * 2) Insure that at least one execute bit is on - otherwise root
	 *	will always succeed, and we don't want to happen unless the
	 *	file really is executable.
	 * 3) Insure that the file is a regular file.
	 */
	if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
	    ((attr->va_mode & 0111) == 0) ||
	    (attr->va_type != VREG))
		return (EACCES);

	/*
	 * Zero length files can't be exec'd
	 */
	if (attr->va_size == 0)
		return (ENOEXEC);

	/*
	 *  Check for execute permission to file based on current credentials.
	 */
	error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
	if (error)
		return (error);

	/*
	 * Check number of open-for-writes on the file and deny execution
	 * if there are any.
	 */
	if (vp->v_writecount)
		return (ETXTBSY);

	/*
	 * Call filesystem specific open routine (which does nothing in the
	 * general case).
	 */
	error = VOP_OPEN(vp, FREAD, td->td_ucred, td);
	return (error);
}

/*
 * Exec handler registration
 */
int
exec_register(execsw_arg)
	const struct execsw *execsw_arg;
{
	const struct execsw **es, **xs, **newexecsw;
	int count = 2;	/* New slot and trailing NULL */

	if (execsw)
		for (es = execsw; *es; es++)
			count++;
	newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
	if (newexecsw == NULL)
		return (ENOMEM);
	xs = newexecsw;
	if (execsw)
		for (es = execsw; *es; es++)
			*xs++ = *es;
	*xs++ = execsw_arg;
	*xs = NULL;
	if (execsw)
		free(execsw, M_TEMP);
	execsw = newexecsw;
	return (0);
}

int
exec_unregister(execsw_arg)
	const struct execsw *execsw_arg;
{
	const struct execsw **es, **xs, **newexecsw;
	int count = 1;

	if (execsw == NULL)
		panic("unregister with no handlers left?\n");

	for (es = execsw; *es; es++) {
		if (*es == execsw_arg)
			break;
	}
	if (*es == NULL)
		return (ENOENT);
	for (es = execsw; *es; es++)
		if (*es != execsw_arg)
			count++;
	newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
	if (newexecsw == NULL)
		return (ENOMEM);
	xs = newexecsw;
	for (es = execsw; *es; es++)
		if (*es != execsw_arg)
			*xs++ = *es;
	*xs = NULL;
	if (execsw)
		free(execsw, M_TEMP);
	execsw = newexecsw;
	return (0);
}
OpenPOWER on IntegriCloud