This repository has been archived by the owner on Apr 19, 2024. It is now read-only.
/
ssh.c
12316 lines (11199 loc) · 384 KB
/
ssh.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
/*
* SSH backend.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <limits.h>
#include <signal.h>
#include "putty.h"
#include "pageant.h" /* for AGENT_MAX_MSGLEN */
#include "tree234.h"
#include "storage.h"
#include "ssh.h"
#ifndef NO_GSSAPI
#include "sshgssc.h"
#include "sshgss.h"
#endif
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
/*
* Packet type contexts, so that ssh2_pkt_type can correctly decode
* the ambiguous type numbers back into the correct type strings.
*/
typedef enum
{
SSH2_PKTCTX_NOKEX,
SSH2_PKTCTX_DHGROUP,
SSH2_PKTCTX_DHGEX,
SSH2_PKTCTX_ECDHKEX,
SSH2_PKTCTX_RSAKEX
} Pkt_KCtx;
typedef enum
{
SSH2_PKTCTX_NOAUTH,
SSH2_PKTCTX_PUBLICKEY,
SSH2_PKTCTX_PASSWORD,
SSH2_PKTCTX_GSSAPI,
SSH2_PKTCTX_KBDINTER
} Pkt_ACtx;
static const char *const ssh2_disconnect_reasons[] = {
NULL,
"host not allowed to connect",
"protocol error",
"key exchange failed",
"host authentication failed",
"MAC error",
"compression error",
"service not available",
"protocol version not supported",
"host key not verifiable",
"connection lost",
"by application",
"too many connections",
"auth cancelled by user",
"no more auth methods available",
"illegal user name",
};
/*
* Various remote-bug flags.
*/
#define BUG_CHOKES_ON_SSH1_IGNORE 1
#define BUG_SSH2_HMAC 2
#define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4
#define BUG_CHOKES_ON_RSA 8
#define BUG_SSH2_RSA_PADDING 16
#define BUG_SSH2_DERIVEKEY 32
#define BUG_SSH2_REKEY 64
#define BUG_SSH2_PK_SESSIONID 128
#define BUG_SSH2_MAXPKT 256
#define BUG_CHOKES_ON_SSH2_IGNORE 512
#define BUG_CHOKES_ON_WINADJ 1024
#define BUG_SENDS_LATE_REQUEST_REPLY 2048
#define BUG_SSH2_OLDGEX 4096
#define DH_MIN_SIZE 1024
#define DH_MAX_SIZE 8192
/*
* Codes for terminal modes.
* Most of these are the same in SSH-1 and SSH-2.
* This list is derived from RFC 4254 and
* SSH-1 RFC-1.2.31.
*/
static const struct ssh_ttymode {
const char *const mode;
int opcode;
enum
{
TTY_OP_CHAR,
TTY_OP_BOOL
} type;
} ssh_ttymodes[] = {
/* "V" prefix discarded for special characters relative to SSH specs */
{"INTR", 1, TTY_OP_CHAR},
{"QUIT", 2, TTY_OP_CHAR},
{"ERASE", 3, TTY_OP_CHAR},
{"KILL", 4, TTY_OP_CHAR},
{"EOF", 5, TTY_OP_CHAR},
{"EOL", 6, TTY_OP_CHAR},
{"EOL2", 7, TTY_OP_CHAR},
{"START", 8, TTY_OP_CHAR},
{"STOP", 9, TTY_OP_CHAR},
{"SUSP", 10, TTY_OP_CHAR},
{"DSUSP", 11, TTY_OP_CHAR},
{"REPRINT", 12, TTY_OP_CHAR},
{"WERASE", 13, TTY_OP_CHAR},
{"LNEXT", 14, TTY_OP_CHAR},
{"FLUSH", 15, TTY_OP_CHAR},
{"SWTCH", 16, TTY_OP_CHAR},
{"STATUS", 17, TTY_OP_CHAR},
{"DISCARD", 18, TTY_OP_CHAR},
{"IGNPAR", 30, TTY_OP_BOOL},
{"PARMRK", 31, TTY_OP_BOOL},
{"INPCK", 32, TTY_OP_BOOL},
{"ISTRIP", 33, TTY_OP_BOOL},
{"INLCR", 34, TTY_OP_BOOL},
{"IGNCR", 35, TTY_OP_BOOL},
{"ICRNL", 36, TTY_OP_BOOL},
{"IUCLC", 37, TTY_OP_BOOL},
{"IXON", 38, TTY_OP_BOOL},
{"IXANY", 39, TTY_OP_BOOL},
{"IXOFF", 40, TTY_OP_BOOL},
{"IMAXBEL", 41, TTY_OP_BOOL},
{"IUTF8", 42, TTY_OP_BOOL},
{"ISIG", 50, TTY_OP_BOOL},
{"ICANON", 51, TTY_OP_BOOL},
{"XCASE", 52, TTY_OP_BOOL},
{"ECHO", 53, TTY_OP_BOOL},
{"ECHOE", 54, TTY_OP_BOOL},
{"ECHOK", 55, TTY_OP_BOOL},
{"ECHONL", 56, TTY_OP_BOOL},
{"NOFLSH", 57, TTY_OP_BOOL},
{"TOSTOP", 58, TTY_OP_BOOL},
{"IEXTEN", 59, TTY_OP_BOOL},
{"ECHOCTL", 60, TTY_OP_BOOL},
{"ECHOKE", 61, TTY_OP_BOOL},
{"PENDIN", 62, TTY_OP_BOOL}, /* XXX is this a real mode? */
{"OPOST", 70, TTY_OP_BOOL},
{"OLCUC", 71, TTY_OP_BOOL},
{"ONLCR", 72, TTY_OP_BOOL},
{"OCRNL", 73, TTY_OP_BOOL},
{"ONOCR", 74, TTY_OP_BOOL},
{"ONLRET", 75, TTY_OP_BOOL},
{"CS7", 90, TTY_OP_BOOL},
{"CS8", 91, TTY_OP_BOOL},
{"PARENB", 92, TTY_OP_BOOL},
{"PARODD", 93, TTY_OP_BOOL}};
/* Miscellaneous other tty-related constants. */
#define SSH_TTY_OP_END 0
/* The opcodes for ISPEED/OSPEED differ between SSH-1 and SSH-2. */
#define SSH1_TTY_OP_ISPEED 192
#define SSH1_TTY_OP_OSPEED 193
#define SSH2_TTY_OP_ISPEED 128
#define SSH2_TTY_OP_OSPEED 129
/* Helper functions for parsing tty-related config. */
static unsigned int ssh_tty_parse_specchar(char *s)
{
unsigned int ret;
if (*s) {
char *next = NULL;
ret = ctrlparse(s, &next);
if (!next)
ret = s[0];
} else {
ret = 255; /* special value meaning "don't set" */
}
return ret;
}
static unsigned int ssh_tty_parse_boolean(char *s)
{
if (stricmp(s, "yes") == 0 || stricmp(s, "on") == 0 ||
stricmp(s, "true") == 0 || stricmp(s, "+") == 0)
return 1; /* true */
else if (stricmp(s, "no") == 0 || stricmp(s, "off") == 0 ||
stricmp(s, "false") == 0 || stricmp(s, "-") == 0)
return 0; /* false */
else
return (atoi(s) != 0);
}
#define translate(x) \
if (type == x) \
return #x
#define translatek(x, ctx) \
if (type == x && (pkt_kctx == ctx)) \
return #x
#define translatea(x, ctx) \
if (type == x && (pkt_actx == ctx)) \
return #x
static const char *ssh1_pkt_type(int type)
{
translate(SSH1_MSG_DISCONNECT);
translate(SSH1_SMSG_PUBLIC_KEY);
translate(SSH1_CMSG_SESSION_KEY);
translate(SSH1_CMSG_USER);
translate(SSH1_CMSG_AUTH_RSA);
translate(SSH1_SMSG_AUTH_RSA_CHALLENGE);
translate(SSH1_CMSG_AUTH_RSA_RESPONSE);
translate(SSH1_CMSG_AUTH_PASSWORD);
translate(SSH1_CMSG_REQUEST_PTY);
translate(SSH1_CMSG_WINDOW_SIZE);
translate(SSH1_CMSG_EXEC_SHELL);
translate(SSH1_CMSG_EXEC_CMD);
translate(SSH1_SMSG_SUCCESS);
translate(SSH1_SMSG_FAILURE);
translate(SSH1_CMSG_STDIN_DATA);
translate(SSH1_SMSG_STDOUT_DATA);
translate(SSH1_SMSG_STDERR_DATA);
translate(SSH1_CMSG_EOF);
translate(SSH1_SMSG_EXIT_STATUS);
translate(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION);
translate(SSH1_MSG_CHANNEL_OPEN_FAILURE);
translate(SSH1_MSG_CHANNEL_DATA);
translate(SSH1_MSG_CHANNEL_CLOSE);
translate(SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION);
translate(SSH1_SMSG_X11_OPEN);
translate(SSH1_CMSG_PORT_FORWARD_REQUEST);
translate(SSH1_MSG_PORT_OPEN);
translate(SSH1_CMSG_AGENT_REQUEST_FORWARDING);
translate(SSH1_SMSG_AGENT_OPEN);
translate(SSH1_MSG_IGNORE);
translate(SSH1_CMSG_EXIT_CONFIRMATION);
translate(SSH1_CMSG_X11_REQUEST_FORWARDING);
translate(SSH1_CMSG_AUTH_RHOSTS_RSA);
translate(SSH1_MSG_DEBUG);
translate(SSH1_CMSG_REQUEST_COMPRESSION);
translate(SSH1_CMSG_AUTH_TIS);
translate(SSH1_SMSG_AUTH_TIS_CHALLENGE);
translate(SSH1_CMSG_AUTH_TIS_RESPONSE);
translate(SSH1_CMSG_AUTH_CCARD);
translate(SSH1_SMSG_AUTH_CCARD_CHALLENGE);
translate(SSH1_CMSG_AUTH_CCARD_RESPONSE);
return "unknown";
}
static const char *ssh2_pkt_type(Pkt_KCtx pkt_kctx, Pkt_ACtx pkt_actx, int type)
{
translatea(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, SSH2_PKTCTX_GSSAPI);
translatea(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, SSH2_PKTCTX_GSSAPI);
translatea(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, SSH2_PKTCTX_GSSAPI);
translatea(SSH2_MSG_USERAUTH_GSSAPI_ERROR, SSH2_PKTCTX_GSSAPI);
translatea(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, SSH2_PKTCTX_GSSAPI);
translatea(SSH2_MSG_USERAUTH_GSSAPI_MIC, SSH2_PKTCTX_GSSAPI);
translate(SSH2_MSG_DISCONNECT);
translate(SSH2_MSG_IGNORE);
translate(SSH2_MSG_UNIMPLEMENTED);
translate(SSH2_MSG_DEBUG);
translate(SSH2_MSG_SERVICE_REQUEST);
translate(SSH2_MSG_SERVICE_ACCEPT);
translate(SSH2_MSG_KEXINIT);
translate(SSH2_MSG_NEWKEYS);
translatek(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP);
translatek(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP);
translatek(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD, SSH2_PKTCTX_DHGEX);
translatek(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
translatek(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
translatek(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
translatek(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
translatek(SSH2_MSG_KEXRSA_PUBKEY, SSH2_PKTCTX_RSAKEX);
translatek(SSH2_MSG_KEXRSA_SECRET, SSH2_PKTCTX_RSAKEX);
translatek(SSH2_MSG_KEXRSA_DONE, SSH2_PKTCTX_RSAKEX);
translatek(SSH2_MSG_KEX_ECDH_INIT, SSH2_PKTCTX_ECDHKEX);
translatek(SSH2_MSG_KEX_ECDH_REPLY, SSH2_PKTCTX_ECDHKEX);
translate(SSH2_MSG_USERAUTH_REQUEST);
translate(SSH2_MSG_USERAUTH_FAILURE);
translate(SSH2_MSG_USERAUTH_SUCCESS);
translate(SSH2_MSG_USERAUTH_BANNER);
translatea(SSH2_MSG_USERAUTH_PK_OK, SSH2_PKTCTX_PUBLICKEY);
translatea(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, SSH2_PKTCTX_PASSWORD);
translatea(SSH2_MSG_USERAUTH_INFO_REQUEST, SSH2_PKTCTX_KBDINTER);
translatea(SSH2_MSG_USERAUTH_INFO_RESPONSE, SSH2_PKTCTX_KBDINTER);
translate(SSH2_MSG_GLOBAL_REQUEST);
translate(SSH2_MSG_REQUEST_SUCCESS);
translate(SSH2_MSG_REQUEST_FAILURE);
translate(SSH2_MSG_CHANNEL_OPEN);
translate(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
translate(SSH2_MSG_CHANNEL_OPEN_FAILURE);
translate(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
translate(SSH2_MSG_CHANNEL_DATA);
translate(SSH2_MSG_CHANNEL_EXTENDED_DATA);
translate(SSH2_MSG_CHANNEL_EOF);
translate(SSH2_MSG_CHANNEL_CLOSE);
translate(SSH2_MSG_CHANNEL_REQUEST);
translate(SSH2_MSG_CHANNEL_SUCCESS);
translate(SSH2_MSG_CHANNEL_FAILURE);
return "unknown";
}
#undef translate
#undef translatec
/* Enumeration values for fields in SSH-1 packets */
enum
{
PKT_END,
PKT_INT,
PKT_CHAR,
PKT_DATA,
PKT_STR,
PKT_BIGNUM,
};
/*
* Coroutine mechanics for the sillier bits of the code. If these
* macros look impenetrable to you, you might find it helpful to
* read
*
* https://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
*
* which explains the theory behind these macros.
*
* In particular, if you are getting `case expression not constant'
* errors when building with MS Visual Studio, this is because MS's
* Edit and Continue debugging feature causes their compiler to
* violate ANSI C. To disable Edit and Continue debugging:
*
* - right-click ssh.c in the FileView
* - click Settings
* - select the C/C++ tab and the General category
* - under `Debug info:', select anything _other_ than `Program
* Database for Edit and Continue'.
*/
#define crBegin(v) \
{ \
int *crLine = &v; \
switch (v) { \
case 0:;
#define crBeginState crBegin(s->crLine)
#define crStateP(t, v) \
struct t *s; \
if (!(v)) { \
s = (v) = snew(struct t); \
s->crLine = 0; \
} \
s = (v);
#define crState(t) crStateP(t, ssh->t)
#define crFinish(z) \
} \
*crLine = 0; \
return (z); \
}
#define crFinishV \
} \
*crLine = 0; \
return; \
}
#define crFinishFree(z) \
} \
sfree(s); \
return (z); \
}
#define crFinishFreeV \
} \
sfree(s); \
return; \
}
#define crReturn(z) \
do { \
*crLine = __LINE__; \
return (z); \
case __LINE__:; \
} while (0)
#define crReturnV \
do { \
*crLine = __LINE__; \
return; \
case __LINE__:; \
} while (0)
#define crStop(z) \
do { \
*crLine = 0; \
return (z); \
} while (0)
#define crStopV \
do { \
*crLine = 0; \
return; \
} while (0)
#define crWaitUntil(c) \
do { \
crReturn(0); \
} while (!(c))
#define crWaitUntilV(c) \
do { \
crReturnV; \
} while (!(c))
struct Packet;
static struct Packet *ssh1_pkt_init(int pkt_type);
static struct Packet *ssh2_pkt_init(int pkt_type);
static void ssh_pkt_ensure(struct Packet *, int length);
static void ssh_pkt_adddata(struct Packet *, const void *data, int len);
static void ssh_pkt_addbyte(struct Packet *, unsigned char value);
static void ssh2_pkt_addbool(struct Packet *, unsigned char value);
static void ssh_pkt_adduint32(struct Packet *, unsigned long value);
static void ssh_pkt_addstring_start(struct Packet *);
static void ssh_pkt_addstring_str(struct Packet *, const char *data);
static void ssh_pkt_addstring_data(struct Packet *, const char *data, int len);
static void ssh_pkt_addstring(struct Packet *, const char *data);
static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
static void ssh1_pkt_addmp(struct Packet *, Bignum b);
static void ssh2_pkt_addmp(struct Packet *, Bignum b);
static int ssh2_pkt_construct(Ssh, struct Packet *);
static void ssh2_pkt_send(Ssh, struct Packet *);
static void ssh2_pkt_send_noqueue(Ssh, struct Packet *);
static int do_ssh1_login(Ssh ssh,
const unsigned char *in,
int inlen,
struct Packet *pktin);
static void do_ssh2_authconn(Ssh ssh,
const unsigned char *in,
int inlen,
struct Packet *pktin);
static void ssh_channel_init(struct ssh_channel *c);
static struct ssh_channel *ssh_channel_msg(Ssh ssh, struct Packet *pktin);
static void ssh_channel_got_eof(struct ssh_channel *c);
static void ssh2_channel_check_close(struct ssh_channel *c);
static void ssh_channel_close_local(struct ssh_channel *c, char const *reason);
static void ssh_channel_destroy(struct ssh_channel *c);
static void ssh_channel_unthrottle(struct ssh_channel *c, int bufsize);
static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin);
/*
* Buffer management constants. There are several of these for
* various different purposes:
*
* - SSH1_BUFFER_LIMIT is the amount of backlog that must build up
* on a local data stream before we throttle the whole SSH
* connection (in SSH-1 only). Throttling the whole connection is
* pretty drastic so we set this high in the hope it won't
* happen very often.
*
* - SSH_MAX_BACKLOG is the amount of backlog that must build up
* on the SSH connection itself before we defensively throttle
* _all_ local data streams. This is pretty drastic too (though
* thankfully unlikely in SSH-2 since the window mechanism should
* ensure that the server never has any need to throttle its end
* of the connection), so we set this high as well.
*
* - OUR_V2_WINSIZE is the default window size we present on SSH-2
* channels.
*
* - OUR_V2_BIGWIN is the window size we advertise for the only
* channel in a simple connection. It must be <= INT_MAX.
*
* - OUR_V2_MAXPKT is the official "maximum packet size" we send
* to the remote side. This actually has nothing to do with the
* size of the _packet_, but is instead a limit on the amount
* of data we're willing to receive in a single SSH2 channel
* data message.
*
* - OUR_V2_PACKETLIMIT is actually the maximum size of SSH
* _packet_ we're prepared to cope with. It must be a multiple
* of the cipher block size, and must be at least 35000.
*/
#define SSH1_BUFFER_LIMIT 32768
#define SSH_MAX_BACKLOG 32768
#define OUR_V2_WINSIZE 16384
#define OUR_V2_BIGWIN 0x7fffffff
#define OUR_V2_MAXPKT 0x4000UL
#define OUR_V2_PACKETLIMIT 0x9000UL
struct ssh_signkey_with_user_pref_id {
const struct ssh_signkey *alg;
int id;
};
const static struct ssh_signkey_with_user_pref_id hostkey_algs[] = {
{&ssh_ecdsa_ed25519, HK_ED25519},
{&ssh_ecdsa_nistp256, HK_ECDSA},
{&ssh_ecdsa_nistp384, HK_ECDSA},
{&ssh_ecdsa_nistp521, HK_ECDSA},
{&ssh_dss, HK_DSA},
{&ssh_rsa, HK_RSA},
};
const static struct ssh_mac *const macs[] = {
&ssh_hmac_sha256, &ssh_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5};
const static struct ssh_mac *const buggymacs[] = {
&ssh_hmac_sha1_buggy, &ssh_hmac_sha1_96_buggy, &ssh_hmac_md5};
static void *ssh_comp_none_init(void)
{
return NULL;
}
static void ssh_comp_none_cleanup(void *handle)
{
}
static int ssh_comp_none_block(void *handle,
unsigned char *block,
int len,
unsigned char **outblock,
int *outlen)
{
return 0;
}
static int ssh_comp_none_disable(void *handle)
{
return 0;
}
const static struct ssh_compress ssh_comp_none = {"none",
NULL,
ssh_comp_none_init,
ssh_comp_none_cleanup,
ssh_comp_none_block,
ssh_comp_none_init,
ssh_comp_none_cleanup,
ssh_comp_none_block,
ssh_comp_none_disable,
NULL};
extern const struct ssh_compress ssh_zlib;
const static struct ssh_compress *const compressions[] = {&ssh_zlib,
&ssh_comp_none};
enum
{ /* channel types */
CHAN_MAINSESSION,
CHAN_X11,
CHAN_AGENT,
CHAN_SOCKDATA,
/*
* CHAN_SHARING indicates a channel which is tracked here on
* behalf of a connection-sharing downstream. We do almost nothing
* with these channels ourselves: all messages relating to them
* get thrown straight to sshshare.c and passed on almost
* unmodified to downstream.
*/
CHAN_SHARING,
/*
* CHAN_ZOMBIE is used to indicate a channel for which we've
* already destroyed the local data source: for instance, if a
* forwarded port experiences a socket error on the local side, we
* immediately destroy its local socket and turn the SSH channel
* into CHAN_ZOMBIE.
*/
CHAN_ZOMBIE
};
typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
typedef void (*cchandler_fn_t)(struct ssh_channel *, struct Packet *, void *);
/*
* Each channel has a queue of outstanding CHANNEL_REQUESTS and their
* handlers.
*/
struct outstanding_channel_request {
cchandler_fn_t handler;
void *ctx;
struct outstanding_channel_request *next;
};
/*
* 2-3-4 tree storing channels.
*/
struct ssh_channel {
Ssh ssh; /* pointer back to main context */
unsigned remoteid, localid;
int type;
/* True if we opened this channel but server hasn't confirmed. */
int halfopen;
/*
* In SSH-1, this value contains four bits:
*
* 1 We have sent SSH1_MSG_CHANNEL_CLOSE.
* 2 We have sent SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
* 4 We have received SSH1_MSG_CHANNEL_CLOSE.
* 8 We have received SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
*
* A channel is completely finished with when all four bits are set.
*
* In SSH-2, the four bits mean:
*
* 1 We have sent SSH2_MSG_CHANNEL_EOF.
* 2 We have sent SSH2_MSG_CHANNEL_CLOSE.
* 4 We have received SSH2_MSG_CHANNEL_EOF.
* 8 We have received SSH2_MSG_CHANNEL_CLOSE.
*
* A channel is completely finished with when we have both sent
* and received CLOSE.
*
* The symbolic constants below use the SSH-2 terminology, which
* is a bit confusing in SSH-1, but we have to use _something_.
*/
#define CLOSES_SENT_EOF 1
#define CLOSES_SENT_CLOSE 2
#define CLOSES_RCVD_EOF 4
#define CLOSES_RCVD_CLOSE 8
int closes;
/*
* This flag indicates that an EOF is pending on the outgoing side
* of the channel: that is, wherever we're getting the data for
* this channel has sent us some data followed by EOF. We can't
* actually send the EOF until we've finished sending the data, so
* we set this flag instead to remind us to do so once our buffer
* is clear.
*/
int pending_eof;
/*
* True if this channel is causing the underlying connection to be
* throttled.
*/
int throttling_conn;
union {
struct ssh2_data_channel {
bufchain outbuffer;
unsigned remwindow, remmaxpkt;
/* locwindow is signed so we can cope with excess data. */
int locwindow, locmaxwin;
/*
* remlocwin is the amount of local window that we think
* the remote end had available to it after it sent the
* last data packet or window adjust ack.
*/
int remlocwin;
/*
* These store the list of channel requests that haven't
* been acked.
*/
struct outstanding_channel_request *chanreq_head, *chanreq_tail;
enum
{
THROTTLED,
UNTHROTTLING,
UNTHROTTLED
} throttle_state;
} v2;
} v;
union {
struct ssh_agent_channel {
bufchain inbuffer;
agent_pending_query *pending;
} a;
struct ssh_x11_channel {
struct X11Connection *xconn;
int initial;
} x11;
struct ssh_pfd_channel {
struct PortForwarding *pf;
} pfd;
struct ssh_sharing_channel {
void *ctx;
} sharing;
} u;
};
/*
* 2-3-4 tree storing remote->local port forwardings. SSH-1 and SSH-2
* use this structure in different ways, reflecting SSH-2's
* altogether saner approach to port forwarding.
*
* In SSH-1, you arrange a remote forwarding by sending the server
* the remote port number, and the local destination host:port.
* When a connection comes in, the server sends you back that
* host:port pair, and you connect to it. This is a ready-made
* security hole if you're not on the ball: a malicious server
* could send you back _any_ host:port pair, so if you trustingly
* connect to the address it gives you then you've just opened the
* entire inside of your corporate network just by connecting
* through it to a dodgy SSH server. Hence, we must store a list of
* host:port pairs we _are_ trying to forward to, and reject a
* connection request from the server if it's not in the list.
*
* In SSH-2, each side of the connection minds its own business and
* doesn't send unnecessary information to the other. You arrange a
* remote forwarding by sending the server just the remote port
* number. When a connection comes in, the server tells you which
* of its ports was connected to; and _you_ have to remember what
* local host:port pair went with that port number.
*
* Hence, in SSH-1 this structure is indexed by destination
* host:port pair, whereas in SSH-2 it is indexed by source port.
*/
struct ssh_portfwd; /* forward declaration */
struct ssh_rportfwd {
unsigned sport, dport;
char *shost, *dhost;
char *sportdesc;
void *share_ctx;
struct ssh_portfwd *pfrec;
};
static void free_rportfwd(struct ssh_rportfwd *pf)
{
if (pf) {
sfree(pf->sportdesc);
sfree(pf->shost);
sfree(pf->dhost);
sfree(pf);
}
}
/*
* Separately to the rportfwd tree (which is for looking up port
* open requests from the server), a tree of _these_ structures is
* used to keep track of all the currently open port forwardings,
* so that we can reconfigure in mid-session if the user requests
* it.
*/
struct ssh_portfwd {
enum
{
DESTROY,
KEEP,
CREATE
} status;
int type;
unsigned sport, dport;
char *saddr, *daddr;
char *sserv, *dserv;
struct ssh_rportfwd *remote;
int addressfamily;
struct PortListener *local;
};
#define free_portfwd(pf) \
(((pf) ? (sfree((pf)->saddr), \
sfree((pf)->daddr), \
sfree((pf)->sserv), \
sfree((pf)->dserv)) \
: (void)0), \
sfree(pf))
struct Packet {
long length; /* length of packet: see below */
long forcepad; /* SSH-2: force padding to at least this length */
int type; /* only used for incoming packets */
unsigned long sequence; /* SSH-2 incoming sequence number */
unsigned char *data; /* allocated storage */
unsigned char *body; /* offset of payload within `data' */
long savedpos; /* dual-purpose saved packet position: see below */
long maxlen; /* amount of storage allocated for `data' */
long encrypted_len; /* for SSH-2 total-size counting */
/*
* A note on the 'length' and 'savedpos' fields above.
*
* Incoming packets are set up so that pkt->length is measured
* relative to pkt->body, which itself points to a few bytes after
* pkt->data (skipping some uninteresting header fields including
* the packet type code). The ssh_pkt_get* functions all expect
* this setup, and they also use pkt->savedpos to indicate how far
* through the packet being decoded they've got - and that, too,
* is an offset from pkt->body rather than pkt->data.
*
* During construction of an outgoing packet, however, pkt->length
* is measured relative to the base pointer pkt->data, and
* pkt->body is not really used for anything until the packet is
* ready for sending. In this mode, pkt->savedpos is reused as a
* temporary variable by the addstring functions, which write out
* a string length field and then keep going back and updating it
* as more data is appended to the subsequent string data field;
* pkt->savedpos stores the offset (again relative to pkt->data)
* of the start of the string data field.
*/
/* Extra metadata used in SSH packet logging mode, allowing us to
* log in the packet header line that the packet came from a
* connection-sharing downstream and what if anything unusual was
* done to it. The additional_log_text field is expected to be a
* static string - it will not be freed. */
unsigned downstream_id;
const char *additional_log_text;
};
static void ssh1_protocol(Ssh ssh,
const void *vin,
int inlen,
struct Packet *pktin);
static void ssh2_protocol(Ssh ssh,
const void *vin,
int inlen,
struct Packet *pktin);
static void ssh2_bare_connection_protocol(Ssh ssh,
const void *vin,
int inlen,
struct Packet *pktin);
static void ssh1_protocol_setup(Ssh ssh);
static void ssh2_protocol_setup(Ssh ssh);
static void ssh2_bare_connection_protocol_setup(Ssh ssh);
static void ssh_size(void *handle, int width, int height);
static void ssh_special(void *handle, Telnet_Special);
static int ssh2_try_send(struct ssh_channel *c);
static int ssh_send_channel_data(struct ssh_channel *c,
const char *buf,
int len);
static void ssh_throttle_all(Ssh ssh, int enable, int bufsize);
static void ssh2_set_window(struct ssh_channel *c, int newwin);
static int ssh_sendbuffer(void *handle);
static int ssh_do_close(Ssh ssh, int notify_exit);
static unsigned long ssh_pkt_getuint32(struct Packet *pkt);
static int ssh2_pkt_getbool(struct Packet *pkt);
static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length);
static void ssh2_timer(void *ctx, unsigned long now);
static void do_ssh2_transport(Ssh ssh,
const void *vin,
int inlen,
struct Packet *pktin);
static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin);
struct rdpkt1_state_tag {
long len, pad, biglen, to_read;
unsigned long realcrc, gotcrc;
unsigned char *p;
int i;
int chunk;
struct Packet *pktin;
};
struct rdpkt2_state_tag {
long len, pad, payload, packetlen, maclen;
int i;
int cipherblk;
unsigned long incoming_sequence;
struct Packet *pktin;
};
struct rdpkt2_bare_state_tag {
char length[4];
long packetlen;
int i;
unsigned long incoming_sequence;
struct Packet *pktin;
};
struct queued_handler;
struct queued_handler {
int msg1, msg2;
chandler_fn_t handler;
void *ctx;
struct queued_handler *next;
};
struct ssh_tag {
const struct plug_function_table *fn;
/* the above field _must_ be first in the structure */
char *v_c, *v_s;
void *exhash;
Socket s;
void *ldisc;
void *logctx;
unsigned char session_key[32];
int v1_compressing;
int v1_remote_protoflags;
int v1_local_protoflags;
int agentfwd_enabled;
int X11_fwd_enabled;
int remote_bugs;
const struct ssh_cipher *cipher;
void *v1_cipher_ctx;
void *crcda_ctx;
const struct ssh2_cipher *cscipher, *sccipher;
void *cs_cipher_ctx, *sc_cipher_ctx;
const struct ssh_mac *csmac, *scmac;
int csmac_etm, scmac_etm;
void *cs_mac_ctx, *sc_mac_ctx;
const struct ssh_compress *cscomp, *sccomp;
void *cs_comp_ctx, *sc_comp_ctx;
const struct ssh_kex *kex;
const struct ssh_signkey *hostkey;
char *hostkey_str; /* string representation, for easy checking in rekeys */
unsigned char v2_session_id[SSH2_KEX_MAX_HASH_LEN];
int v2_session_id_len;
void *kex_ctx;
int bare_connection;
int attempting_connshare;
void *connshare;
char *savedhost;
int savedport;
int send_ok;
int echoing, editing;
int session_started;
void *frontend;
int ospeed, ispeed; /* temporaries */
int term_width, term_height;
tree234 *channels; /* indexed by local id */
struct ssh_channel *mainchan; /* primary session channel */
int ncmode; /* is primary channel direct-tcpip? */
int exitcode;
int close_expected;
int clean_exit;
tree234 *rportfwds, *portfwds;
enum
{
SSH_STATE_PREPACKET,
SSH_STATE_BEFORE_SIZE,
SSH_STATE_INTERMED,
SSH_STATE_SESSION,
SSH_STATE_CLOSED
} state;
int size_needed, eof_needed;
int sent_console_eof;
int got_pty; /* affects EOF behaviour on main channel */
struct Packet **queue;
int queuelen, queuesize;
int queueing;
unsigned char *deferred_send_data;
int deferred_len, deferred_size;
/*
* Gross hack: pscp will try to start SFTP but fall back to
* scp1 if that fails. This variable is the means by which
* scp.c can reach into the SSH code and find out which one it
* got.
*/
int fallback_cmd;
bufchain banner; /* accumulates banners during do_ssh2_authconn */
Pkt_KCtx pkt_kctx;
Pkt_ACtx pkt_actx;
struct X11Display *x11disp;
struct X11FakeAuth *x11auth;
tree234 *x11authtree;
int version;
int conn_throttle_count;
int overall_bufsize;
int throttled_all;
int v1_stdout_throttling;
unsigned long v2_outgoing_sequence;
int ssh1_rdpkt_crstate;
int ssh2_rdpkt_crstate;
int ssh2_bare_rdpkt_crstate;
int ssh_gotdata_crstate;
int do_ssh1_connection_crstate;
void *do_ssh_init_state;
void *do_ssh1_login_state;
void *do_ssh2_transport_state;
void *do_ssh2_authconn_state;
void *do_ssh_connection_init_state;
struct rdpkt1_state_tag rdpkt1_state;
struct rdpkt2_state_tag rdpkt2_state;
struct rdpkt2_bare_state_tag rdpkt2_bare_state;
/* SSH-1 and SSH-2 use this for different things, but both use it */
int protocol_initial_phase_done;
void (*protocol)(Ssh ssh, const void *vin, int inlen, struct Packet *pkt);
struct Packet *(*s_rdpkt)(Ssh ssh, const unsigned char **data, int *datalen);
int (*do_ssh_init)(Ssh ssh, unsigned char c);
/*
* We maintain our own copy of a Conf structure here. That way,
* when we're passed a new one for reconfiguration, we can check
* the differences and potentially reconfigure port forwardings
* etc in mid-session.
*/
Conf *conf;
/*
* Values cached out of conf so as to avoid the tree234 lookup
* cost every time they're used.
*/
int logomitdata;
/*
* Dynamically allocated username string created during SSH
* login. Stored in here rather than in the coroutine state so
* that it'll be reliably freed if we shut down the SSH session
* at some unexpected moment.
*/
char *username;
/*
* Used to transfer data back from async callbacks.
*/
void *agent_response;
int agent_response_len;