forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 17
/
feat.c
1564 lines (1390 loc) · 47 KB
/
feat.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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/dccp/feat.c
*
* Feature negotiation for the DCCP protocol (RFC 4340, section 6)
*
* Copyright (c) 2008 Gerrit Renker <[email protected]>
* Rewrote from scratch, some bits from earlier code by
* Copyright (c) 2005 Andrea Bittau <[email protected]>
*
* ASSUMPTIONS
* -----------
* o Feature negotiation is coordinated with connection setup (as in TCP), wild
* changes of parameters of an established connection are not supported.
* o Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN.
* o All currently known SP features have 1-byte quantities. If in the future
* extensions of RFCs 4340..42 define features with item lengths larger than
* one byte, a feature-specific extension of the code will be required.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include "ccid.h"
#include "feat.h"
/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
int sysctl_dccp_rx_ccid __read_mostly = 2,
sysctl_dccp_tx_ccid __read_mostly = 2;
/*
* Feature activation handlers.
*
* These all use an u64 argument, to provide enough room for NN/SP features. At
* this stage the negotiated values have been checked to be within their range.
*/
static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid *new_ccid = ccid_new(ccid, sk, rx);
if (new_ccid == NULL)
return -ENOMEM;
if (rx) {
ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
dp->dccps_hc_rx_ccid = new_ccid;
} else {
ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
dp->dccps_hc_tx_ccid = new_ccid;
}
return 0;
}
static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
if (rx) {
dp->dccps_r_seq_win = seq_win;
/* propagate changes to update SWL/SWH */
dccp_update_gsr(sk, dp->dccps_gsr);
} else {
dp->dccps_l_seq_win = seq_win;
/* propagate changes to update AWL */
dccp_update_gss(sk, dp->dccps_gss);
}
return 0;
}
static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
{
if (rx)
dccp_sk(sk)->dccps_r_ack_ratio = ratio;
else
dccp_sk(sk)->dccps_l_ack_ratio = ratio;
return 0;
}
static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
if (rx) {
if (enable && dp->dccps_hc_rx_ackvec == NULL) {
dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
if (dp->dccps_hc_rx_ackvec == NULL)
return -ENOMEM;
} else if (!enable) {
dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
dp->dccps_hc_rx_ackvec = NULL;
}
}
return 0;
}
static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
{
if (!rx)
dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
return 0;
}
/*
* Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
* `rx' holds when the sending peer informs about his partial coverage via a
* ChangeR() option. In the other case, we are the sender and the receiver
* announces its coverage via ChangeL() options. The policy here is to honour
* such communication by enabling the corresponding partial coverage - but only
* if it has not been set manually before; the warning here means that all
* packets will be dropped.
*/
static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
if (rx)
dp->dccps_pcrlen = cscov;
else {
if (dp->dccps_pcslen == 0)
dp->dccps_pcslen = cscov;
else if (cscov > dp->dccps_pcslen)
DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
dp->dccps_pcslen, (u8)cscov);
}
return 0;
}
static const struct {
u8 feat_num; /* DCCPF_xxx */
enum dccp_feat_type rxtx; /* RX or TX */
enum dccp_feat_type reconciliation; /* SP or NN */
u8 default_value; /* as in 6.4 */
int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
/*
* Lookup table for location and type of features (from RFC 4340/4342)
* +--------------------------+----+-----+----+----+---------+-----------+
* | Feature | Location | Reconc. | Initial | Section |
* | | RX | TX | SP | NN | Value | Reference |
* +--------------------------+----+-----+----+----+---------+-----------+
* | DCCPF_CCID | | X | X | | 2 | 10 |
* | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
* | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
* | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
* | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
* | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
* | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
* | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
* | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
* | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
* +--------------------------+----+-----+----+----+---------+-----------+
*/
} dccp_feat_table[] = {
{ DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
{ DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
{ DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
{ DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
{ DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
{ DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
{ DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
{ DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
{ DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
{ DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
};
#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
/**
* dccp_feat_index - Hash function to map feature number into array position
* Returns consecutive array index or -1 if the feature is not understood.
*/
static int dccp_feat_index(u8 feat_num)
{
/* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
return feat_num - 1;
/*
* Other features: add cases for new feature types here after adding
* them to the above table.
*/
switch (feat_num) {
case DCCPF_SEND_LEV_RATE:
return DCCP_FEAT_SUPPORTED_MAX - 1;
}
return -1;
}
static u8 dccp_feat_type(u8 feat_num)
{
int idx = dccp_feat_index(feat_num);
if (idx < 0)
return FEAT_UNKNOWN;
return dccp_feat_table[idx].reconciliation;
}
static int dccp_feat_default_value(u8 feat_num)
{
int idx = dccp_feat_index(feat_num);
/*
* There are no default values for unknown features, so encountering a
* negative index here indicates a serious problem somewhere else.
*/
DCCP_BUG_ON(idx < 0);
return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
}
/*
* Debugging and verbose-printing section
*/
static const char *dccp_feat_fname(const u8 feat)
{
static const char *const feature_names[] = {
[DCCPF_RESERVED] = "Reserved",
[DCCPF_CCID] = "CCID",
[DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
[DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
[DCCPF_ECN_INCAPABLE] = "ECN Incapable",
[DCCPF_ACK_RATIO] = "Ack Ratio",
[DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
[DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
[DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
[DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
};
if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
return feature_names[DCCPF_RESERVED];
if (feat == DCCPF_SEND_LEV_RATE)
return "Send Loss Event Rate";
if (feat >= DCCPF_MIN_CCID_SPECIFIC)
return "CCID-specific";
return feature_names[feat];
}
static const char *const dccp_feat_sname[] = {
"DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
};
#ifdef CONFIG_IP_DCCP_DEBUG
static const char *dccp_feat_oname(const u8 opt)
{
switch (opt) {
case DCCPO_CHANGE_L: return "Change_L";
case DCCPO_CONFIRM_L: return "Confirm_L";
case DCCPO_CHANGE_R: return "Change_R";
case DCCPO_CONFIRM_R: return "Confirm_R";
}
return NULL;
}
static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val)
{
u8 i, type = dccp_feat_type(feat_num);
if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL))
dccp_pr_debug_cat("(NULL)");
else if (type == FEAT_SP)
for (i = 0; i < val->sp.len; i++)
dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]);
else if (type == FEAT_NN)
dccp_pr_debug_cat("%llu", (unsigned long long)val->nn);
else
dccp_pr_debug_cat("unknown type %u", type);
}
static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len)
{
u8 type = dccp_feat_type(feat_num);
dccp_feat_val fval = { .sp.vec = list, .sp.len = len };
if (type == FEAT_NN)
fval.nn = dccp_decode_value_var(list, len);
dccp_feat_printval(feat_num, &fval);
}
static void dccp_feat_print_entry(struct dccp_feat_entry const *entry)
{
dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote",
dccp_feat_fname(entry->feat_num));
dccp_feat_printval(entry->feat_num, &entry->val);
dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state],
entry->needs_confirm ? "(Confirm pending)" : "");
}
#define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \
dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\
dccp_feat_printvals(feat, val, len); \
dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0)
#define dccp_feat_print_fnlist(fn_list) { \
const struct dccp_feat_entry *___entry; \
\
dccp_pr_debug("List Dump:\n"); \
list_for_each_entry(___entry, fn_list, node) \
dccp_feat_print_entry(___entry); \
}
#else /* ! CONFIG_IP_DCCP_DEBUG */
#define dccp_feat_print_opt(opt, feat, val, len, mandatory)
#define dccp_feat_print_fnlist(fn_list)
#endif
static int __dccp_feat_activate(struct sock *sk, const int idx,
const bool is_local, dccp_feat_val const *fval)
{
bool rx;
u64 val;
if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
return -1;
if (dccp_feat_table[idx].activation_hdlr == NULL)
return 0;
if (fval == NULL) {
val = dccp_feat_table[idx].default_value;
} else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
if (fval->sp.vec == NULL) {
/*
* This can happen when an empty Confirm is sent
* for an SP (i.e. known) feature. In this case
* we would be using the default anyway.
*/
DCCP_CRIT("Feature #%d undefined: using default", idx);
val = dccp_feat_table[idx].default_value;
} else {
val = fval->sp.vec[0];
}
} else {
val = fval->nn;
}
/* Location is RX if this is a local-RX or remote-TX feature */
rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX",
dccp_feat_fname(dccp_feat_table[idx].feat_num),
fval ? "" : "default ", (unsigned long long)val);
return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
}
/**
* dccp_feat_activate - Activate feature value on socket
* @sk: fully connected DCCP socket (after handshake is complete)
* @feat_num: feature to activate, one of %dccp_feature_numbers
* @local: whether local (1) or remote (0) @feat_num is meant
* @fval: the value (SP or NN) to activate, or NULL to use the default value
*
* For general use this function is preferable over __dccp_feat_activate().
*/
static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
dccp_feat_val const *fval)
{
return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
}
/* Test for "Req'd" feature (RFC 4340, 6.4) */
static inline int dccp_feat_must_be_understood(u8 feat_num)
{
return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
feat_num == DCCPF_SEQUENCE_WINDOW;
}
/* copy constructor, fval must not already contain allocated memory */
static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
{
fval->sp.len = len;
if (fval->sp.len > 0) {
fval->sp.vec = kmemdup(val, len, gfp_any());
if (fval->sp.vec == NULL) {
fval->sp.len = 0;
return -ENOBUFS;
}
}
return 0;
}
static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
{
if (unlikely(val == NULL))
return;
if (dccp_feat_type(feat_num) == FEAT_SP)
kfree(val->sp.vec);
memset(val, 0, sizeof(*val));
}
static struct dccp_feat_entry *
dccp_feat_clone_entry(struct dccp_feat_entry const *original)
{
struct dccp_feat_entry *new;
u8 type = dccp_feat_type(original->feat_num);
if (type == FEAT_UNKNOWN)
return NULL;
new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
if (new == NULL)
return NULL;
if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
original->val.sp.vec,
original->val.sp.len)) {
kfree(new);
return NULL;
}
return new;
}
static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
{
if (entry != NULL) {
dccp_feat_val_destructor(entry->feat_num, &entry->val);
kfree(entry);
}
}
/*
* List management functions
*
* Feature negotiation lists rely on and maintain the following invariants:
* - each feat_num in the list is known, i.e. we know its type and default value
* - each feat_num/is_local combination is unique (old entries are overwritten)
* - SP values are always freshly allocated
* - list is sorted in increasing order of feature number (faster lookup)
*/
static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
u8 feat_num, bool is_local)
{
struct dccp_feat_entry *entry;
list_for_each_entry(entry, fn_list, node) {
if (entry->feat_num == feat_num && entry->is_local == is_local)
return entry;
else if (entry->feat_num > feat_num)
break;
}
return NULL;
}
/**
* dccp_feat_entry_new - Central list update routine (called by all others)
* @head: list to add to
* @feat: feature number
* @local: whether the local (1) or remote feature with number @feat is meant
*
* This is the only constructor and serves to ensure the above invariants.
*/
static struct dccp_feat_entry *
dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
{
struct dccp_feat_entry *entry;
list_for_each_entry(entry, head, node)
if (entry->feat_num == feat && entry->is_local == local) {
dccp_feat_val_destructor(entry->feat_num, &entry->val);
return entry;
} else if (entry->feat_num > feat) {
head = &entry->node;
break;
}
entry = kmalloc(sizeof(*entry), gfp_any());
if (entry != NULL) {
entry->feat_num = feat;
entry->is_local = local;
list_add_tail(&entry->node, head);
}
return entry;
}
/**
* dccp_feat_push_change - Add/overwrite a Change option in the list
* @fn_list: feature-negotiation list to update
* @feat: one of %dccp_feature_numbers
* @local: whether local (1) or remote (0) @feat_num is meant
* @mandatory: whether to use Mandatory feature negotiation options
* @fval: pointer to NN/SP value to be inserted (will be copied)
*/
static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
u8 mandatory, dccp_feat_val *fval)
{
struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
if (new == NULL)
return -ENOMEM;
new->feat_num = feat;
new->is_local = local;
new->state = FEAT_INITIALISING;
new->needs_confirm = false;
new->empty_confirm = false;
new->val = *fval;
new->needs_mandatory = mandatory;
return 0;
}
/**
* dccp_feat_push_confirm - Add a Confirm entry to the FN list
* @fn_list: feature-negotiation list to add to
* @feat: one of %dccp_feature_numbers
* @local: whether local (1) or remote (0) @feat_num is being confirmed
* @fval: pointer to NN/SP value to be inserted or NULL
*
* Returns 0 on success, a Reset code for further processing otherwise.
*/
static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
dccp_feat_val *fval)
{
struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
if (new == NULL)
return DCCP_RESET_CODE_TOO_BUSY;
new->feat_num = feat;
new->is_local = local;
new->state = FEAT_STABLE; /* transition in 6.6.2 */
new->needs_confirm = true;
new->empty_confirm = (fval == NULL);
new->val.nn = 0; /* zeroes the whole structure */
if (!new->empty_confirm)
new->val = *fval;
new->needs_mandatory = false;
return 0;
}
static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
{
return dccp_feat_push_confirm(fn_list, feat, local, NULL);
}
static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
{
list_del(&entry->node);
dccp_feat_entry_destructor(entry);
}
void dccp_feat_list_purge(struct list_head *fn_list)
{
struct dccp_feat_entry *entry, *next;
list_for_each_entry_safe(entry, next, fn_list, node)
dccp_feat_entry_destructor(entry);
INIT_LIST_HEAD(fn_list);
}
EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
/* generate @to as full clone of @from - @to must not contain any nodes */
int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
{
struct dccp_feat_entry *entry, *new;
INIT_LIST_HEAD(to);
list_for_each_entry(entry, from, node) {
new = dccp_feat_clone_entry(entry);
if (new == NULL)
goto cloning_failed;
list_add_tail(&new->node, to);
}
return 0;
cloning_failed:
dccp_feat_list_purge(to);
return -ENOMEM;
}
/**
* dccp_feat_valid_nn_length - Enforce length constraints on NN options
* Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
* incoming options are accepted as long as their values are valid.
*/
static u8 dccp_feat_valid_nn_length(u8 feat_num)
{
if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
return 2;
if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
return 6;
return 0;
}
static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
{
switch (feat_num) {
case DCCPF_ACK_RATIO:
return val <= DCCPF_ACK_RATIO_MAX;
case DCCPF_SEQUENCE_WINDOW:
return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
}
return 0; /* feature unknown - so we can't tell */
}
/* check that SP values are within the ranges defined in RFC 4340 */
static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
{
switch (feat_num) {
case DCCPF_CCID:
return val == DCCPC_CCID2 || val == DCCPC_CCID3;
/* Type-check Boolean feature values: */
case DCCPF_SHORT_SEQNOS:
case DCCPF_ECN_INCAPABLE:
case DCCPF_SEND_ACK_VECTOR:
case DCCPF_SEND_NDP_COUNT:
case DCCPF_DATA_CHECKSUM:
case DCCPF_SEND_LEV_RATE:
return val < 2;
case DCCPF_MIN_CSUM_COVER:
return val < 16;
}
return 0; /* feature unknown */
}
static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
{
if (sp_list == NULL || sp_len < 1)
return 0;
while (sp_len--)
if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
return 0;
return 1;
}
/**
* dccp_feat_insert_opts - Generate FN options from current list state
* @skb: next sk_buff to be sent to the peer
* @dp: for client during handshake and general negotiation
* @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
*/
int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
struct sk_buff *skb)
{
struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
struct dccp_feat_entry *pos, *next;
u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
bool rpt;
/* put entries into @skb in the order they appear in the list */
list_for_each_entry_safe_reverse(pos, next, fn, node) {
opt = dccp_feat_genopt(pos);
type = dccp_feat_type(pos->feat_num);
rpt = false;
if (pos->empty_confirm) {
len = 0;
ptr = NULL;
} else {
if (type == FEAT_SP) {
len = pos->val.sp.len;
ptr = pos->val.sp.vec;
rpt = pos->needs_confirm;
} else if (type == FEAT_NN) {
len = dccp_feat_valid_nn_length(pos->feat_num);
ptr = nn_in_nbo;
dccp_encode_value_var(pos->val.nn, ptr, len);
} else {
DCCP_BUG("unknown feature %u", pos->feat_num);
return -1;
}
}
dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
return -1;
if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
return -1;
if (skb->sk->sk_state == DCCP_OPEN &&
(opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) {
/*
* Confirms don't get retransmitted (6.6.3) once the
* connection is in state OPEN
*/
dccp_feat_list_pop(pos);
} else {
/*
* Enter CHANGING after transmitting the Change
* option (6.6.2).
*/
if (pos->state == FEAT_INITIALISING)
pos->state = FEAT_CHANGING;
}
}
return 0;
}
/**
* __feat_register_nn - Register new NN value on socket
* @fn: feature-negotiation list to register with
* @feat: an NN feature from %dccp_feature_numbers
* @mandatory: use Mandatory option if 1
* @nn_val: value to register (restricted to 4 bytes)
*
* Note that NN features are local by definition (RFC 4340, 6.3.2).
*/
static int __feat_register_nn(struct list_head *fn, u8 feat,
u8 mandatory, u64 nn_val)
{
dccp_feat_val fval = { .nn = nn_val };
if (dccp_feat_type(feat) != FEAT_NN ||
!dccp_feat_is_valid_nn_val(feat, nn_val))
return -EINVAL;
/* Don't bother with default values, they will be activated anyway. */
if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
return 0;
return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
}
/**
* __feat_register_sp - Register new SP value/list on socket
* @fn: feature-negotiation list to register with
* @feat: an SP feature from %dccp_feature_numbers
* @is_local: whether the local (1) or the remote (0) @feat is meant
* @mandatory: use Mandatory option if 1
* @sp_val: SP value followed by optional preference list
* @sp_len: length of @sp_val in bytes
*/
static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
u8 mandatory, u8 const *sp_val, u8 sp_len)
{
dccp_feat_val fval;
if (dccp_feat_type(feat) != FEAT_SP ||
!dccp_feat_sp_list_ok(feat, sp_val, sp_len))
return -EINVAL;
/* Avoid negotiating alien CCIDs by only advertising supported ones */
if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
return -EOPNOTSUPP;
if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
return -ENOMEM;
if (dccp_feat_push_change(fn, feat, is_local, mandatory, &fval)) {
kfree(fval.sp.vec);
return -ENOMEM;
}
return 0;
}
/**
* dccp_feat_register_sp - Register requests to change SP feature values
* @sk: client or listening socket
* @feat: one of %dccp_feature_numbers
* @is_local: whether the local (1) or remote (0) @feat is meant
* @list: array of preferred values, in descending order of preference
* @len: length of @list in bytes
*/
int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
u8 const *list, u8 len)
{ /* any changes must be registered before establishing the connection */
if (sk->sk_state != DCCP_CLOSED)
return -EISCONN;
if (dccp_feat_type(feat) != FEAT_SP)
return -EINVAL;
return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
0, list, len);
}
/**
* dccp_feat_nn_get - Query current/pending value of NN feature
* @sk: DCCP socket of an established connection
* @feat: NN feature number from %dccp_feature_numbers
*
* For a known NN feature, returns value currently being negotiated, or
* current (confirmed) value if no negotiation is going on.
*/
u64 dccp_feat_nn_get(struct sock *sk, u8 feat)
{
if (dccp_feat_type(feat) == FEAT_NN) {
struct dccp_sock *dp = dccp_sk(sk);
struct dccp_feat_entry *entry;
entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1);
if (entry != NULL)
return entry->val.nn;
switch (feat) {
case DCCPF_ACK_RATIO:
return dp->dccps_l_ack_ratio;
case DCCPF_SEQUENCE_WINDOW:
return dp->dccps_l_seq_win;
}
}
DCCP_BUG("attempt to look up unsupported feature %u", feat);
return 0;
}
EXPORT_SYMBOL_GPL(dccp_feat_nn_get);
/**
* dccp_feat_signal_nn_change - Update NN values for an established connection
* @sk: DCCP socket of an established connection
* @feat: NN feature number from %dccp_feature_numbers
* @nn_val: the new value to use
*
* This function is used to communicate NN updates out-of-band.
*/
int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val)
{
struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
dccp_feat_val fval = { .nn = nn_val };
struct dccp_feat_entry *entry;
if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN)
return 0;
if (dccp_feat_type(feat) != FEAT_NN ||
!dccp_feat_is_valid_nn_val(feat, nn_val))
return -EINVAL;
if (nn_val == dccp_feat_nn_get(sk, feat))
return 0; /* already set or negotiation under way */
entry = dccp_feat_list_lookup(fn, feat, 1);
if (entry != NULL) {
dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n",
(unsigned long long)entry->val.nn,
(unsigned long long)nn_val);
dccp_feat_list_pop(entry);
}
inet_csk_schedule_ack(sk);
return dccp_feat_push_change(fn, feat, 1, 0, &fval);
}
EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change);
/*
* Tracking features whose value depend on the choice of CCID
*
* This is designed with an extension in mind so that a list walk could be done
* before activating any features. However, the existing framework was found to
* work satisfactorily up until now, the automatic verification is left open.
* When adding new CCIDs, add a corresponding dependency table here.
*/
static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
{
static const struct ccid_dependency ccid2_dependencies[2][2] = {
/*
* CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
* feature and Send Ack Vector is an RX feature, `is_local'
* needs to be reversed.
*/
{ /* Dependencies of the receiver-side (remote) CCID2 */
{
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = true,
.is_mandatory = true,
.val = 1
},
{ 0, 0, 0, 0 }
},
{ /* Dependencies of the sender-side (local) CCID2 */
{
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = false,
.is_mandatory = true,
.val = 1
},
{ 0, 0, 0, 0 }
}
};
static const struct ccid_dependency ccid3_dependencies[2][5] = {
{ /*
* Dependencies of the receiver-side CCID3
*/
{ /* locally disable Ack Vectors */
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = true,
.is_mandatory = false,
.val = 0
},
{ /* see below why Send Loss Event Rate is on */
.dependent_feat = DCCPF_SEND_LEV_RATE,
.is_local = true,
.is_mandatory = true,
.val = 1
},
{ /* NDP Count is needed as per RFC 4342, 6.1.1 */
.dependent_feat = DCCPF_SEND_NDP_COUNT,
.is_local = false,
.is_mandatory = true,
.val = 1
},
{ 0, 0, 0, 0 },
},
{ /*
* CCID3 at the TX side: we request that the HC-receiver
* will not send Ack Vectors (they will be ignored, so
* Mandatory is not set); we enable Send Loss Event Rate
* (Mandatory since the implementation does not support
* the Loss Intervals option of RFC 4342, 8.6).
* The last two options are for peer's information only.
*/
{
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = false,
.is_mandatory = false,
.val = 0
},
{
.dependent_feat = DCCPF_SEND_LEV_RATE,
.is_local = false,
.is_mandatory = true,
.val = 1
},
{ /* this CCID does not support Ack Ratio */
.dependent_feat = DCCPF_ACK_RATIO,
.is_local = true,
.is_mandatory = false,
.val = 0
},
{ /* tell receiver we are sending NDP counts */
.dependent_feat = DCCPF_SEND_NDP_COUNT,
.is_local = true,
.is_mandatory = false,
.val = 1
},
{ 0, 0, 0, 0 }
}
};
switch (ccid) {
case DCCPC_CCID2:
return ccid2_dependencies[is_local];
case DCCPC_CCID3:
return ccid3_dependencies[is_local];
default:
return NULL;
}
}
/**
* dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
* @fn: feature-negotiation list to update
* @id: CCID number to track
* @is_local: whether TX CCID (1) or RX CCID (0) is meant
*
* This function needs to be called after registering all other features.
*/
static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
{
const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
int i, rc = (table == NULL);
for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
rc = __feat_register_sp(fn, table[i].dependent_feat,
table[i].is_local,
table[i].is_mandatory,
&table[i].val, 1);
else
rc = __feat_register_nn(fn, table[i].dependent_feat,
table[i].is_mandatory,
table[i].val);
return rc;
}
/**
* dccp_feat_finalise_settings - Finalise settings before starting negotiation
* @dp: client or listening socket (settings will be inherited)
*
* This is called after all registrations (socket initialisation, sysctls, and
* sockopt calls), and before sending the first packet containing Change options
* (ie. client-Request or server-Response), to ensure internal consistency.
*/
int dccp_feat_finalise_settings(struct dccp_sock *dp)
{
struct list_head *fn = &dp->dccps_featneg;
struct dccp_feat_entry *entry;
int i = 2, ccids[2] = { -1, -1 };
/*
* Propagating CCIDs:
* 1) not useful to propagate CCID settings if this host advertises more
* than one CCID: the choice of CCID may still change - if this is
* the client, or if this is the server and the client sends
* singleton CCID values.
* 2) since is that propagate_ccid changes the list, we defer changing
* the sorted list until after the traversal.
*/
list_for_each_entry(entry, fn, node)
if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
ccids[entry->is_local] = entry->val.sp.vec[0];
while (i--)
if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
return -1;
dccp_feat_print_fnlist(fn);
return 0;
}
/**
* dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
* It is the server which resolves the dependencies once the CCID has been
* fully negotiated. If no CCID has been negotiated, it uses the default CCID.
*/
int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
{
struct list_head *fn = &dreq->dreq_featneg;