-
Notifications
You must be signed in to change notification settings - Fork 38
/
cap-ng.c
1319 lines (1186 loc) · 29.9 KB
/
cap-ng.c
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
/* libcap-ng.c --
* Copyright 2009-10, 2013, 2017, 2020 Red Hat Inc.
* All Rights Reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Authors:
* Steve Grubb <sgrubb@redhat.com>
*/
#include "config.h"
#include "cap-ng.h"
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <pwd.h>
#include <grp.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <endian.h>
#include <byteswap.h>
#ifdef HAVE_PTHREAD_H
#include <pthread.h> // For pthread_atfork
#endif
#ifdef HAVE_SYSCALL_H
#include <sys/syscall.h>
#endif
#ifdef HAVE_LINUX_SECUREBITS_H
#include <linux/securebits.h>
#endif
# define hidden __attribute__ ((visibility ("hidden")))
unsigned int last_cap hidden = 0;
/*
* Some milestones of when things became available:
* 2.6.24 kernel XATTR_NAME_CAPS
* 2.6.25 kernel PR_CAPBSET_DROP, CAPABILITY_VERSION_2
* 2.6.26 kernel PR_SET_SECUREBITS, SECURE_*_LOCKED, VERSION_3
* 4.3 kernel PR_CAP_AMBIENT
* 4.14 kernel VFS_CAP_REVISION_3
*/
/* External syscall prototypes */
extern int capset(cap_user_header_t header, cap_user_data_t data);
extern int capget(cap_user_header_t header, const cap_user_data_t data);
// Local functions
static void update_bounding_set(capng_act_t action, unsigned int capability,
unsigned int idx);
static void update_ambient_set(capng_act_t action, unsigned int capability,
unsigned int idx);
// Local defines
#define MASK(x) (1U << (x))
#ifdef PR_CAPBSET_DROP
#define UPPER_MASK ~((~0U)<<(last_cap-31))
#else
// For v1 systems UPPER_MASK will never be used
#define UPPER_MASK (unsigned)(~0U)
#endif
// Re-define cap_valid so its uniform between V1 and V3
#undef cap_valid
#define cap_valid(x) ((x) <= last_cap)
// If we don't have the xattr library, then we can't
// compile-in file system capabilities
#if !defined(HAVE_ATTR_XATTR_H) && !defined (HAVE_SYS_XATTR_H)
#undef VFS_CAP_U32
#endif
#ifdef VFS_CAP_U32
#ifdef HAVE_SYS_XATTR_H
#include <sys/xattr.h>
#else
#ifdef HAVE_ATTR_XATTR_H
#include <attr/xattr.h>
#endif
#endif
#if __BYTE_ORDER == __BIG_ENDIAN
#define FIXUP(x) bswap_32(x)
#else
#define FIXUP(x) (x)
#endif
#endif
#ifndef _LINUX_CAPABILITY_VERSION_1
#define _LINUX_CAPABILITY_VERSION_1 0x19980330
#endif
#ifndef _LINUX_CAPABILITY_VERSION_2
#define _LINUX_CAPABILITY_VERSION_2 0x20071026
#endif
#ifndef _LINUX_CAPABILITY_VERSION_3
#define _LINUX_CAPABILITY_VERSION_3 0x20080522
#endif
// This public API went private in the 2.6.36 kernel - hope it never changes
#ifndef XATTR_CAPS_SUFFIX
#define XATTR_CAPS_SUFFIX "capability"
#endif
#ifndef XATTR_SECURITY_PREFIX
#define XATTR_SECURITY_PREFIX "security."
#endif
#ifndef XATTR_NAME_CAPS
#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
#endif
/* Child processes can't get caps back */
#ifndef SECURE_NOROOT
#define SECURE_NOROOT 0
#endif
#ifndef SECURE_NOROOT_LOCKED
#define SECURE_NOROOT_LOCKED 1 /* make bit-0 immutable */
#endif
/* Setuid apps run by uid 0 don't get caps back */
#ifndef SECURE_NO_SETUID_FIXUP
#define SECURE_NO_SETUID_FIXUP 2
#endif
#ifndef SECURE_NO_SETUID_FIXUP_LOCKED
#define SECURE_NO_SETUID_FIXUP_LOCKED 3 /* make bit-2 immutable */
#endif
#ifndef VFS_CAP_U32
#define VFS_CAP_U32 2
#endif
#if (VFS_CAP_U32 != 2)
#error VFS_CAP_U32 does not match the library, you need a new version
#endif
// States: new, allocated, initted, updated, applied
typedef enum { CAPNG_NEW, CAPNG_ERROR, CAPNG_ALLOCATED, CAPNG_INIT,
CAPNG_UPDATED, CAPNG_APPLIED } capng_states_t;
// Create an easy data struct out of the kernel definitions
typedef union {
struct __user_cap_data_struct v1;
struct __user_cap_data_struct v3[VFS_CAP_U32];
} cap_data_t;
// This struct keeps all state info
struct cap_ng
{
int cap_ver;
int vfs_cap_ver;
struct __user_cap_header_struct hdr;
cap_data_t data;
capng_states_t state;
__le32 rootid;
__u32 bounds[VFS_CAP_U32];
__u32 ambient[VFS_CAP_U32];
};
// Global variables with per thread uniqueness
static __thread struct cap_ng m = { 1, 1,
{0, 0},
{ {0, 0, 0} },
CAPNG_NEW, CAPNG_UNSET_ROOTID,
{0, 0},
{0, 0} };
/*
* Reset the state so that init gets called to erase everything
*/
static void deinit(void)
{
m.state = CAPNG_NEW;
}
static void init_lib(void) __attribute__ ((constructor));
static void init_lib(void)
{
#ifdef HAVE_PTHREAD_H
pthread_atfork(NULL, NULL, deinit);
#endif
// Detect last cap
if (last_cap == 0) {
int fd;
fd = open("/proc/sys/kernel/cap_last_cap", O_RDONLY);
if (fd >= 0) {
char buf[8];
int num = read(fd, buf, sizeof(buf) - 1);
if (num > 0) {
buf[num] = 0;
errno = 0;
unsigned int val = strtoul(buf, NULL, 10);
if (errno == 0)
last_cap = val;
}
close(fd);
}
if (last_cap == 0)
last_cap = CAP_LAST_CAP;
}
}
static void init(void)
{
if (m.state != CAPNG_NEW)
return;
memset(&m.hdr, 0, sizeof(m.hdr));
(void)capget(&m.hdr, NULL); // Returns -EINVAL
if (m.hdr.version == _LINUX_CAPABILITY_VERSION_3 ||
m.hdr.version == _LINUX_CAPABILITY_VERSION_2) {
m.cap_ver = 3;
} else if (m.hdr.version == _LINUX_CAPABILITY_VERSION_1) {
m.cap_ver = 1;
} else {
m.state = CAPNG_ERROR;
return;
}
#if VFS_CAP_REVISION == VFS_CAP_REVISION_1
m.vfs_cap_ver = 1;
#else
m.vfs_cap_ver = 2; // Intentionally set to 2 for both 2 & 3
#endif
memset(&m.data, 0, sizeof(cap_data_t));
#ifdef HAVE_SYSCALL_H
m.hdr.pid = (unsigned)syscall(__NR_gettid);
#else
m.hdr.pid = (unsigned)getpid();
#endif
m.rootid = CAPNG_UNSET_ROOTID;
m.state = CAPNG_ALLOCATED;
}
void capng_clear(capng_select_t set)
{
if (m.state == CAPNG_NEW)
init();
if (m.state == CAPNG_ERROR)
return;
if (set & CAPNG_SELECT_CAPS)
memset(&m.data, 0, sizeof(cap_data_t));
#ifdef PR_CAPBSET_DROP
if (set & CAPNG_SELECT_BOUNDS)
memset(m.bounds, 0, sizeof(m.bounds));
#endif
#ifdef PR_CAP_AMBIENT
if (set & CAPNG_SELECT_AMBIENT)
memset(m.ambient, 0, sizeof(m.ambient));
#endif
m.state = CAPNG_INIT;
}
void capng_fill(capng_select_t set)
{
if (m.state == CAPNG_NEW)
init();
if (m.state == CAPNG_ERROR)
return;
if (set & CAPNG_SELECT_CAPS) {
if (m.cap_ver == 1) {
m.data.v1.effective = 0x7FFFFFFFU;
m.data.v1.permitted = 0x7FFFFFFFU;
m.data.v1.inheritable = 0;
} else {
m.data.v3[0].effective = 0xFFFFFFFFU;
m.data.v3[0].permitted = 0xFFFFFFFFU;
m.data.v3[0].inheritable = 0;
m.data.v3[1].effective = 0xFFFFFFFFU;
m.data.v3[1].permitted = 0xFFFFFFFFU;
m.data.v3[1].inheritable = 0;
}
}
#ifdef PR_CAPBSET_DROP
if (set & CAPNG_SELECT_BOUNDS) {
unsigned i;
for (i=0; i<sizeof(m.bounds)/sizeof(__u32); i++)
m.bounds[i] = 0xFFFFFFFFU;
}
#endif
#ifdef PR_CAP_AMBIENT
if (set & CAPNG_SELECT_AMBIENT) {
unsigned i;
for (i=0; i<sizeof(m.ambient)/sizeof(__u32); i++)
m.ambient[i] = 0xFFFFFFFFU;
}
#endif
m.state = CAPNG_INIT;
}
void capng_setpid(int pid)
{
if (m.state == CAPNG_NEW)
init();
if (m.state == CAPNG_ERROR)
return;
m.hdr.pid = pid;
}
int capng_get_rootid(void)
{
#ifdef VFS_CAP_REVISION_3
return m.rootid;
#else
return CAPNG_UNSET_ROOTID;
#endif
}
int capng_set_rootid(int rootid)
{
#ifdef VFS_CAP_REVISION_3
if (m.state == CAPNG_NEW)
init();
if (m.state == CAPNG_ERROR)
return -1;
if (rootid < 0)
return -1;
m.rootid = rootid;
m.vfs_cap_ver = 3;
return 0;
#else
return -1;
#endif
}
#ifdef PR_CAPBSET_DROP
static int get_bounding_set(void)
{
char buf[64];
FILE *f;
int rc;
snprintf(buf, sizeof(buf), "/proc/%d/status", m.hdr.pid ? m.hdr.pid :
#ifdef HAVE_SYSCALL_H
(int)syscall(__NR_gettid));
#else
(int)getpid();
#endif
f = fopen(buf, "re");
if (f) {
__fsetlocking(f, FSETLOCKING_BYCALLER);
while (fgets(buf, sizeof(buf), f)) {
if (strncmp(buf, "CapB", 4))
continue;
sscanf(buf, "CapBnd: %08x%08x",
&m.bounds[1], &m.bounds[0]);
fclose(f);
return 0;
}
// Didn't find bounding set, fall through and try prctl way
fclose(f);
}
// Might be in a container with no procfs - do it the hard way
memset(m.bounds, 0, sizeof(m.bounds));
unsigned int i = 0;
do {
rc = prctl(PR_CAPBSET_READ, i, 0, 0, 0);
if (rc < 0)
return -1;
// Just add set bits
if (rc)
update_bounding_set(CAPNG_ADD, i%32, i>>5);
i++;
} while (cap_valid(i));
return 0;
}
#endif
#ifdef PR_CAP_AMBIENT
static int get_ambient_set(void)
{
char buf[64];
FILE *f;
int rc;
snprintf(buf, sizeof(buf), "/proc/%d/status", m.hdr.pid ? m.hdr.pid :
#ifdef HAVE_SYSCALL_H
(int)syscall(__NR_gettid));
#else
(int)getpid();
#endif
f = fopen(buf, "re");
if (f) {
__fsetlocking(f, FSETLOCKING_BYCALLER);
while (fgets(buf, sizeof(buf), f)) {
if (strncmp(buf, "CapA", 4))
continue;
sscanf(buf, "CapAmb: %08x%08x",
&m.ambient[1], &m.ambient[0]);
fclose(f);
return 0;
}
fclose(f);
// Didn't find ambient set, fall through and try prctl way
}
// Might be in a container with no procfs - do it the hard way
memset(m.ambient, 0, sizeof(m.ambient));
unsigned int i = 0;
do {
rc = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, i, 0, 0);
if (rc < 0)
return -1;
// Just add set bits
if (rc)
update_ambient_set(CAPNG_ADD, i%32, i>>5);
i++;
} while (cap_valid(i));
return 0;
}
#endif
int capng_get_caps_process(void)
{
int rc;
if (m.state == CAPNG_NEW)
init();
if (m.state == CAPNG_ERROR)
return -1;
rc = capget((cap_user_header_t)&m.hdr, (cap_user_data_t)&m.data);
if (rc == 0) {
m.state = CAPNG_INIT;
#ifdef PR_CAPBSET_DROP
rc = get_bounding_set();
if (rc < 0)
m.state = CAPNG_ERROR;
#endif
#ifdef PR_CAP_AMBIENT
rc = get_ambient_set();
if (rc < 0)
m.state = CAPNG_ERROR;
#endif
}
return rc;
}
#ifdef VFS_CAP_U32
#ifdef VFS_CAP_REVISION_3
static int load_data(const struct vfs_ns_cap_data *filedata, int size)
#else
static int load_data(const struct vfs_cap_data *filedata, int size)
#endif
{
unsigned int magic;
if (m.cap_ver == 1)
return -1; // Should never get here but just in case
magic = FIXUP(filedata->magic_etc);
switch (magic & VFS_CAP_REVISION_MASK)
{
case VFS_CAP_REVISION_1:
m.vfs_cap_ver = 1;
if (size != XATTR_CAPS_SZ_1)
return -1;
break;
case VFS_CAP_REVISION_2:
m.vfs_cap_ver = 2;
if (size != XATTR_CAPS_SZ_2)
return -1;
break;
#ifdef VFS_CAP_REVISION_3
case VFS_CAP_REVISION_3:
m.vfs_cap_ver = 3;
if (size != XATTR_CAPS_SZ_3)
return -1;
break;
#endif
default:
return -1;
}
// Now stuff the data structures
m.data.v3[0].permitted = FIXUP(filedata->data[0].permitted);
m.data.v3[1].permitted = FIXUP(filedata->data[1].permitted);
m.data.v3[0].inheritable = FIXUP(filedata->data[0].inheritable);
m.data.v3[1].inheritable = FIXUP(filedata->data[1].inheritable);
if (magic & VFS_CAP_FLAGS_EFFECTIVE) {
m.data.v3[0].effective =
m.data.v3[0].permitted | m.data.v3[0].inheritable;
m.data.v3[1].effective =
m.data.v3[1].permitted | m.data.v3[1].inheritable;
} else {
m.data.v3[0].effective = 0;
m.data.v3[1].effective = 0;
}
#ifdef VFS_CAP_REVISION_3
if (size == XATTR_CAPS_SZ_3) {
struct vfs_ns_cap_data *d = (struct vfs_ns_cap_data *)filedata;
m.rootid = FIXUP(d->rootid);
}
#endif
return 0;
}
#endif
int capng_get_caps_fd(int fd)
{
#ifndef VFS_CAP_U32
return -1;
#else
int rc;
#ifdef VFS_CAP_REVISION_3
struct vfs_ns_cap_data filedata;
#else
struct vfs_cap_data filedata;
#endif
if (m.state == CAPNG_NEW)
init();
if (m.state == CAPNG_ERROR)
return -1;
rc = fgetxattr(fd, XATTR_NAME_CAPS, &filedata, sizeof(filedata));
if (rc <= 0)
return -1;
rc = load_data(&filedata, rc);
if (rc == 0)
m.state = CAPNG_INIT;
return rc;
#endif
}
static void v1_update(capng_act_t action, unsigned int capability, __u32 *data)
{
if (action == CAPNG_ADD)
*data |= MASK(capability);
else
*data &= ~(MASK(capability));
}
static void update_effective(capng_act_t action, unsigned int capability,
unsigned int idx)
{
if (action == CAPNG_ADD)
m.data.v3[idx].effective |= MASK(capability);
else
m.data.v3[idx].effective &= ~(MASK(capability));
}
static void update_permitted(capng_act_t action, unsigned int capability,
unsigned int idx)
{
if (action == CAPNG_ADD)
m.data.v3[idx].permitted |= MASK(capability);
else
m.data.v3[idx].permitted &= ~(MASK(capability));
}
static void update_inheritable(capng_act_t action, unsigned int capability,
unsigned int idx)
{
if (action == CAPNG_ADD)
m.data.v3[idx].inheritable |= MASK(capability);
else
m.data.v3[idx].inheritable &= ~(MASK(capability));
}
static void update_bounding_set(capng_act_t action, unsigned int capability,
unsigned int idx)
{
#ifdef PR_CAPBSET_DROP
if (action == CAPNG_ADD)
m.bounds[idx] |= MASK(capability);
else
m.bounds[idx] &= ~(MASK(capability));
#endif
}
static void update_ambient_set(capng_act_t action, unsigned int capability,
unsigned int idx)
{
#ifdef PR_CAP_AMBIENT
if (action == CAPNG_ADD)
m.ambient[idx] |= MASK(capability);
else
m.ambient[idx] &= ~(MASK(capability));
#endif
}
int capng_update(capng_act_t action, capng_type_t type, unsigned int capability)
{
// Before updating, we expect that the data is initialized to something
if (m.state < CAPNG_INIT)
return -1;
if (!cap_valid(capability)) {
errno = EINVAL;
return -1;
}
if (m.cap_ver == 1) {
if (CAPNG_EFFECTIVE & type)
v1_update(action, capability, &m.data.v1.effective);
if (CAPNG_PERMITTED & type)
v1_update(action, capability, &m.data.v1.permitted);
if (CAPNG_INHERITABLE & type)
v1_update(action, capability, &m.data.v1.inheritable);
} else {
unsigned int idx;
if (capability > 31) {
idx = capability>>5;
capability %= 32;
} else
idx = 0;
if (CAPNG_EFFECTIVE & type)
update_effective(action, capability, idx);
if (CAPNG_PERMITTED & type)
update_permitted(action, capability, idx);
if (CAPNG_INHERITABLE & type)
update_inheritable(action, capability, idx);
if (CAPNG_BOUNDING_SET & type)
update_bounding_set(action, capability, idx);
if (CAPNG_AMBIENT & type)
update_ambient_set(action, capability, idx);
}
m.state = CAPNG_UPDATED;
return 0;
}
int capng_updatev(capng_act_t action, capng_type_t type,
unsigned int capability, ...)
{
int rc;
unsigned int cap;
va_list ap;
rc = capng_update(action, type, capability);
if (rc)
return rc;
va_start(ap, capability);
cap = va_arg(ap, unsigned int);
while (cap_valid(cap)) {
rc = capng_update(action, type, cap);
if (rc)
break;
cap = va_arg(ap, unsigned int);
}
va_end(ap);
// See if planned exit or invalid
if (cap == (unsigned)-1)
rc = 0;
else {
rc = -1;
errno = EINVAL;
}
return rc;
}
int capng_apply(capng_select_t set)
{
// Before updating, we expect that the data is initialized to something
if (m.state < CAPNG_INIT)
return -1;
if (set & CAPNG_SELECT_BOUNDS) {
#ifdef PR_CAPBSET_DROP
struct cap_ng state;
memcpy(&state, &m, sizeof(state)); /* save state */
capng_get_caps_process();
if (capng_have_capability(CAPNG_EFFECTIVE, CAP_SETPCAP)) {
unsigned int i;
memcpy(&m, &state, sizeof(m)); /* restore state */
for (i=0; i <= last_cap; i++) {
if (capng_have_capability(CAPNG_BOUNDING_SET,
i) == 0) {
if (prctl(PR_CAPBSET_DROP, i, 0, 0, 0) <0)
return -2;
}
}
m.state = CAPNG_APPLIED;
if (get_bounding_set() < 0)
return -3;
} else {
memcpy(&m, &state, sizeof(m)); /* restore state */
return -4;
}
#endif
}
if (set & CAPNG_SELECT_CAPS) {
if (capset((cap_user_header_t)&m.hdr,
(cap_user_data_t)&m.data) == 0)
m.state = CAPNG_APPLIED;
else
return -5;
}
// Put ambient last so that inheritable and permitted are set
if (set & CAPNG_SELECT_AMBIENT) {
#ifdef PR_CAP_AMBIENT
if (capng_have_capabilities(CAPNG_SELECT_AMBIENT) ==
CAPNG_NONE) {
if (prctl(PR_CAP_AMBIENT,
PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0) < 0)
return -6;
} else {
unsigned int i;
// Clear them all
if (prctl(PR_CAP_AMBIENT,
PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0) < 0)
return -7;
for (i=0; i <= last_cap; i++) {
if (capng_have_capability(CAPNG_AMBIENT, i))
if (prctl(PR_CAP_AMBIENT,
PR_CAP_AMBIENT_RAISE, i, 0, 0) < 0)
return -8;
}
}
m.state = CAPNG_APPLIED;
#endif
}
return 0;
}
#ifdef VFS_CAP_U32
#ifdef VFS_CAP_REVISION_3
static int save_data(struct vfs_ns_cap_data *filedata, int *size)
#else
static int save_data(struct vfs_cap_data *filedata, int *size)
#endif
{
// Now stuff the data structures
if (m.vfs_cap_ver == 1) {
filedata->data[0].permitted = FIXUP(m.data.v1.permitted);
filedata->data[0].inheritable = FIXUP(m.data.v1.inheritable);
filedata->magic_etc = FIXUP(VFS_CAP_REVISION_1);
*size = XATTR_CAPS_SZ_1;
} else if (m.vfs_cap_ver == 2 || m.vfs_cap_ver == 3) {
int eff;
if (m.data.v3[0].effective || m.data.v3[1].effective)
eff = VFS_CAP_FLAGS_EFFECTIVE;
else
eff = 0;
filedata->data[0].permitted = FIXUP(m.data.v3[0].permitted);
filedata->data[0].inheritable = FIXUP(m.data.v3[0].inheritable);
filedata->data[1].permitted = FIXUP(m.data.v3[1].permitted);
filedata->data[1].inheritable = FIXUP(m.data.v3[1].inheritable);
filedata->magic_etc = FIXUP(VFS_CAP_REVISION_2 | eff);
*size = XATTR_CAPS_SZ_2;
}
#ifdef VFS_CAP_REVISION_3
if (m.vfs_cap_ver == 3) {
// Kernel doesn't support namespaces with non-0 rootid
if (m.rootid!= 0)
return -1;
filedata->rootid = FIXUP(m.rootid);
*size = XATTR_CAPS_SZ_3;
}
#endif
return 0;
}
#endif
int capng_apply_caps_fd(int fd)
{
#ifndef VFS_CAP_U32
return -1;
#else
int rc, size = 0;
#ifdef VFS_CAP_REVISION_3
struct vfs_ns_cap_data filedata;
#else
struct vfs_cap_data filedata;
#endif
struct stat buf;
// Before updating, we expect that the data is initialized to something
if (m.state < CAPNG_INIT)
return -1;
if (fstat(fd, &buf) != 0)
return -1;
if (S_ISLNK(buf.st_mode) || !S_ISREG(buf.st_mode)) {
errno = EINVAL;
return -1;
}
if (capng_have_capabilities(CAPNG_SELECT_CAPS) == CAPNG_NONE)
rc = fremovexattr(fd, XATTR_NAME_CAPS);
else {
if (save_data(&filedata, &size)) {
m.state = CAPNG_ERROR;
errno = EINVAL;
return -2;
}
rc = fsetxattr(fd, XATTR_NAME_CAPS, &filedata, size, 0);
}
if (rc == 0)
m.state = CAPNG_APPLIED;
return rc;
#endif
}
// Change uids keeping/removing only certain capabilities
// flag to drop supp groups
int capng_change_id(int uid, int gid, capng_flags_t flag)
{
int rc, need_setgid, need_setuid;
// Before updating, we expect that the data is initialized to something
if (m.state < CAPNG_INIT)
return -1;
// Check the current capabilities
#ifdef PR_CAPBSET_DROP
// If newer kernel, we need setpcap to change the bounding set
if (capng_have_capability(CAPNG_EFFECTIVE, CAP_SETPCAP) == 0 &&
flag & CAPNG_CLEAR_BOUNDING)
capng_update(CAPNG_ADD,
CAPNG_EFFECTIVE|CAPNG_PERMITTED, CAP_SETPCAP);
#endif
if (gid == -1 || capng_have_capability(CAPNG_EFFECTIVE, CAP_SETGID))
need_setgid = 0;
else {
need_setgid = 1;
capng_update(CAPNG_ADD, CAPNG_EFFECTIVE|CAPNG_PERMITTED,
CAP_SETGID);
}
if (uid == -1 || capng_have_capability(CAPNG_EFFECTIVE, CAP_SETUID))
need_setuid = 0;
else {
need_setuid = 1;
capng_update(CAPNG_ADD, CAPNG_EFFECTIVE|CAPNG_PERMITTED,
CAP_SETUID);
}
// Tell system we want to keep caps across uid change
if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0))
return -2;
// Change to the temp capabilities
rc = capng_apply(CAPNG_SELECT_CAPS);
if (rc < 0)
return -3;
// If we are clearing ambient, only clear since its applied at the end
if (flag & CAPNG_CLEAR_AMBIENT)
capng_clear(CAPNG_SELECT_AMBIENT);
// Clear bounding set if needed while we have CAP_SETPCAP
if (flag & CAPNG_CLEAR_BOUNDING) {
capng_clear(CAPNG_SELECT_BOUNDS);
rc = capng_apply(CAPNG_SELECT_BOUNDS);
if (rc)
return -8;
}
// Change gid
if (gid != -1) {
rc = setresgid(gid, gid, gid);
if (rc)
return -4;
}
// See if we need to init supplemental groups
if ((flag & CAPNG_INIT_SUPP_GRP) && uid != -1) {
struct passwd *pw = getpwuid(uid);
if (pw == NULL)
return -10;
if (gid != -1) {
if (initgroups(pw->pw_name, gid))
return -5;
} else if (initgroups(pw->pw_name, pw->pw_gid))
return -5;
}
// See if we need to unload supplemental groups
if ((flag & CAPNG_DROP_SUPP_GRP) && gid != -1) {
if (setgroups(0, NULL))
return -5;
}
// Change uid
if (uid != -1) {
rc = setresuid(uid, uid, uid);
if (rc)
return -6;
}
// Tell it we are done keeping capabilities
rc = prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0);
if (rc)
return -7;
// Now throw away CAP_SETPCAP so no more changes
if (need_setgid)
capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED,
CAP_SETGID);
if (need_setuid)
capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED,
CAP_SETUID);
// Now drop setpcap & apply
capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED,
CAP_SETPCAP);
rc = capng_apply(CAPNG_SELECT_CAPS|CAPNG_SELECT_AMBIENT);
if (rc < 0)
return -9;
// Done
m.state = CAPNG_UPDATED;
return 0;
}
int capng_lock(void)
{
// If either fail, return -1 since something is not right
#ifdef PR_SET_SECUREBITS
int rc = prctl(PR_SET_SECUREBITS,
1 << SECURE_NOROOT |
1 << SECURE_NOROOT_LOCKED |
1 << SECURE_NO_SETUID_FIXUP |
1 << SECURE_NO_SETUID_FIXUP_LOCKED, 0, 0, 0);
#ifdef PR_SET_NO_NEW_PRIVS
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
return -1;
#endif
if (rc)
return -1;
#endif
return 0;
}
// -1 - error, 0 - no caps, 1 partial caps, 2 full caps
capng_results_t capng_have_capabilities(capng_select_t set)
{
int empty = 0, full = 0;
// First, try to init with current set
if (m.state < CAPNG_INIT)
capng_get_caps_process();
// If we still don't have anything, error out
if (m.state < CAPNG_INIT)
return CAPNG_FAIL;
if (set & CAPNG_SELECT_CAPS) {
if (m.cap_ver == 1) {
if (m.data.v1.effective == 0)
empty = 1;
// after fill, 30 bits starts from upper to lower
else if (m.data.v1.effective == 0x7FFFFFFFU)
full = 1;
// actual capabilities read from system
else if (m.data.v1.effective == 0xFFFFFEFFU)
full = 1;
else
return CAPNG_PARTIAL;
} else {
if (m.data.v3[0].effective == 0)
empty = 1;
else if (m.data.v3[0].effective == 0xFFFFFFFFU)
full = 1;
else
return CAPNG_PARTIAL;
if ((m.data.v3[1].effective & UPPER_MASK) == 0 && !full)
empty = 1;
else if ((m.data.v3[1].effective & UPPER_MASK) ==
UPPER_MASK && !empty)
full = 1;
else
return CAPNG_PARTIAL;
}
}
#ifdef PR_CAPBSET_DROP