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1/*
2 * net/dccp/feat.c
3 *
4 * Feature negotiation for the DCCP protocol (RFC 4340, section 6)
5 *
6 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
7 * Rewrote from scratch, some bits from earlier code by
8 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
9 *
10 *
11 * ASSUMPTIONS
12 * -----------
13 * o Feature negotiation is coordinated with connection setup (as in TCP), wild
14 * changes of parameters of an established connection are not supported.
15 * o All currently known SP features have 1-byte quantities. If in the future
16 * extensions of RFCs 4340..42 define features with item lengths larger than
17 * one byte, a feature-specific extension of the code will be required.
18 *
19 * This program is free software; you can redistribute it and/or
20 * modify it under the terms of the GNU General Public License
21 * as published by the Free Software Foundation; either version
22 * 2 of the License, or (at your option) any later version.
23 */
24#include <linux/module.h>
25#include <linux/slab.h>
26#include "ccid.h"
27#include "feat.h"
28
29/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
30unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
31int sysctl_dccp_rx_ccid __read_mostly = 2,
32 sysctl_dccp_tx_ccid __read_mostly = 2;
33
34/*
35 * Feature activation handlers.
36 *
37 * These all use an u64 argument, to provide enough room for NN/SP features. At
38 * this stage the negotiated values have been checked to be within their range.
39 */
40static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
41{
42 struct dccp_sock *dp = dccp_sk(sk);
43 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
44
45 if (new_ccid == NULL)
46 return -ENOMEM;
47
48 if (rx) {
49 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
50 dp->dccps_hc_rx_ccid = new_ccid;
51 } else {
52 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
53 dp->dccps_hc_tx_ccid = new_ccid;
54 }
55 return 0;
56}
57
58static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
59{
60 struct dccp_sock *dp = dccp_sk(sk);
61
62 if (rx) {
63 dp->dccps_r_seq_win = seq_win;
64 /* propagate changes to update SWL/SWH */
65 dccp_update_gsr(sk, dp->dccps_gsr);
66 } else {
67 dp->dccps_l_seq_win = seq_win;
68 /* propagate changes to update AWL */
69 dccp_update_gss(sk, dp->dccps_gss);
70 }
71 return 0;
72}
73
74static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
75{
76 if (rx)
77 dccp_sk(sk)->dccps_r_ack_ratio = ratio;
78 else
79 dccp_sk(sk)->dccps_l_ack_ratio = ratio;
80 return 0;
81}
82
83static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
84{
85 struct dccp_sock *dp = dccp_sk(sk);
86
87 if (rx) {
88 if (enable && dp->dccps_hc_rx_ackvec == NULL) {
89 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
90 if (dp->dccps_hc_rx_ackvec == NULL)
91 return -ENOMEM;
92 } else if (!enable) {
93 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
94 dp->dccps_hc_rx_ackvec = NULL;
95 }
96 }
97 return 0;
98}
99
100static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
101{
102 if (!rx)
103 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
104 return 0;
105}
106
107/*
108 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
109 * `rx' holds when the sending peer informs about his partial coverage via a
110 * ChangeR() option. In the other case, we are the sender and the receiver
111 * announces its coverage via ChangeL() options. The policy here is to honour
112 * such communication by enabling the corresponding partial coverage - but only
113 * if it has not been set manually before; the warning here means that all
114 * packets will be dropped.
115 */
116static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
117{
118 struct dccp_sock *dp = dccp_sk(sk);
119
120 if (rx)
121 dp->dccps_pcrlen = cscov;
122 else {
123 if (dp->dccps_pcslen == 0)
124 dp->dccps_pcslen = cscov;
125 else if (cscov > dp->dccps_pcslen)
126 DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
127 dp->dccps_pcslen, (u8)cscov);
128 }
129 return 0;
130}
131
132static const struct {
133 u8 feat_num; /* DCCPF_xxx */
134 enum dccp_feat_type rxtx; /* RX or TX */
135 enum dccp_feat_type reconciliation; /* SP or NN */
136 u8 default_value; /* as in 6.4 */
137 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
138/*
139 * Lookup table for location and type of features (from RFC 4340/4342)
140 * +--------------------------+----+-----+----+----+---------+-----------+
141 * | Feature | Location | Reconc. | Initial | Section |
142 * | | RX | TX | SP | NN | Value | Reference |
143 * +--------------------------+----+-----+----+----+---------+-----------+
144 * | DCCPF_CCID | | X | X | | 2 | 10 |
145 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
146 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
147 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
148 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
149 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
150 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
151 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
152 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
153 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
154 * +--------------------------+----+-----+----+----+---------+-----------+
155 */
156} dccp_feat_table[] = {
157 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
158 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
159 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
160 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
161 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
162 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
163 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
164 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
165 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
166 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
167};
168#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
169
170/**
171 * dccp_feat_index - Hash function to map feature number into array position
172 * Returns consecutive array index or -1 if the feature is not understood.
173 */
174static int dccp_feat_index(u8 feat_num)
175{
176 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
177 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
178 return feat_num - 1;
179
180 /*
181 * Other features: add cases for new feature types here after adding
182 * them to the above table.
183 */
184 switch (feat_num) {
185 case DCCPF_SEND_LEV_RATE:
186 return DCCP_FEAT_SUPPORTED_MAX - 1;
187 }
188 return -1;
189}
190
191static u8 dccp_feat_type(u8 feat_num)
192{
193 int idx = dccp_feat_index(feat_num);
194
195 if (idx < 0)
196 return FEAT_UNKNOWN;
197 return dccp_feat_table[idx].reconciliation;
198}
199
200static int dccp_feat_default_value(u8 feat_num)
201{
202 int idx = dccp_feat_index(feat_num);
203 /*
204 * There are no default values for unknown features, so encountering a
205 * negative index here indicates a serious problem somewhere else.
206 */
207 DCCP_BUG_ON(idx < 0);
208
209 return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
210}
211
212/*
213 * Debugging and verbose-printing section
214 */
215static const char *dccp_feat_fname(const u8 feat)
216{
217 static const char *const feature_names[] = {
218 [DCCPF_RESERVED] = "Reserved",
219 [DCCPF_CCID] = "CCID",
220 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
221 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
222 [DCCPF_ECN_INCAPABLE] = "ECN Incapable",
223 [DCCPF_ACK_RATIO] = "Ack Ratio",
224 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
225 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
226 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
227 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
228 };
229 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
230 return feature_names[DCCPF_RESERVED];
231
232 if (feat == DCCPF_SEND_LEV_RATE)
233 return "Send Loss Event Rate";
234 if (feat >= DCCPF_MIN_CCID_SPECIFIC)
235 return "CCID-specific";
236
237 return feature_names[feat];
238}
239
240static const char *const dccp_feat_sname[] = {
241 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
242};
243
244#ifdef CONFIG_IP_DCCP_DEBUG
245static const char *dccp_feat_oname(const u8 opt)
246{
247 switch (opt) {
248 case DCCPO_CHANGE_L: return "Change_L";
249 case DCCPO_CONFIRM_L: return "Confirm_L";
250 case DCCPO_CHANGE_R: return "Change_R";
251 case DCCPO_CONFIRM_R: return "Confirm_R";
252 }
253 return NULL;
254}
255
256static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val)
257{
258 u8 i, type = dccp_feat_type(feat_num);
259
260 if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL))
261 dccp_pr_debug_cat("(NULL)");
262 else if (type == FEAT_SP)
263 for (i = 0; i < val->sp.len; i++)
264 dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]);
265 else if (type == FEAT_NN)
266 dccp_pr_debug_cat("%llu", (unsigned long long)val->nn);
267 else
268 dccp_pr_debug_cat("unknown type %u", type);
269}
270
271static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len)
272{
273 u8 type = dccp_feat_type(feat_num);
274 dccp_feat_val fval = { .sp.vec = list, .sp.len = len };
275
276 if (type == FEAT_NN)
277 fval.nn = dccp_decode_value_var(list, len);
278 dccp_feat_printval(feat_num, &fval);
279}
280
281static void dccp_feat_print_entry(struct dccp_feat_entry const *entry)
282{
283 dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote",
284 dccp_feat_fname(entry->feat_num));
285 dccp_feat_printval(entry->feat_num, &entry->val);
286 dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state],
287 entry->needs_confirm ? "(Confirm pending)" : "");
288}
289
290#define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \
291 dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\
292 dccp_feat_printvals(feat, val, len); \
293 dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0)
294
295#define dccp_feat_print_fnlist(fn_list) { \
296 const struct dccp_feat_entry *___entry; \
297 \
298 dccp_pr_debug("List Dump:\n"); \
299 list_for_each_entry(___entry, fn_list, node) \
300 dccp_feat_print_entry(___entry); \
301}
302#else /* ! CONFIG_IP_DCCP_DEBUG */
303#define dccp_feat_print_opt(opt, feat, val, len, mandatory)
304#define dccp_feat_print_fnlist(fn_list)
305#endif
306
307static int __dccp_feat_activate(struct sock *sk, const int idx,
308 const bool is_local, dccp_feat_val const *fval)
309{
310 bool rx;
311 u64 val;
312
313 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
314 return -1;
315 if (dccp_feat_table[idx].activation_hdlr == NULL)
316 return 0;
317
318 if (fval == NULL) {
319 val = dccp_feat_table[idx].default_value;
320 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
321 if (fval->sp.vec == NULL) {
322 /*
323 * This can happen when an empty Confirm is sent
324 * for an SP (i.e. known) feature. In this case
325 * we would be using the default anyway.
326 */
327 DCCP_CRIT("Feature #%d undefined: using default", idx);
328 val = dccp_feat_table[idx].default_value;
329 } else {
330 val = fval->sp.vec[0];
331 }
332 } else {
333 val = fval->nn;
334 }
335
336 /* Location is RX if this is a local-RX or remote-TX feature */
337 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
338
339 dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX",
340 dccp_feat_fname(dccp_feat_table[idx].feat_num),
341 fval ? "" : "default ", (unsigned long long)val);
342
343 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
344}
345
346/* Test for "Req'd" feature (RFC 4340, 6.4) */
347static inline int dccp_feat_must_be_understood(u8 feat_num)
348{
349 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
350 feat_num == DCCPF_SEQUENCE_WINDOW;
351}
352
353/* copy constructor, fval must not already contain allocated memory */
354static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
355{
356 fval->sp.len = len;
357 if (fval->sp.len > 0) {
358 fval->sp.vec = kmemdup(val, len, gfp_any());
359 if (fval->sp.vec == NULL) {
360 fval->sp.len = 0;
361 return -ENOBUFS;
362 }
363 }
364 return 0;
365}
366
367static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
368{
369 if (unlikely(val == NULL))
370 return;
371 if (dccp_feat_type(feat_num) == FEAT_SP)
372 kfree(val->sp.vec);
373 memset(val, 0, sizeof(*val));
374}
375
376static struct dccp_feat_entry *
377 dccp_feat_clone_entry(struct dccp_feat_entry const *original)
378{
379 struct dccp_feat_entry *new;
380 u8 type = dccp_feat_type(original->feat_num);
381
382 if (type == FEAT_UNKNOWN)
383 return NULL;
384
385 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
386 if (new == NULL)
387 return NULL;
388
389 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
390 original->val.sp.vec,
391 original->val.sp.len)) {
392 kfree(new);
393 return NULL;
394 }
395 return new;
396}
397
398static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
399{
400 if (entry != NULL) {
401 dccp_feat_val_destructor(entry->feat_num, &entry->val);
402 kfree(entry);
403 }
404}
405
406/*
407 * List management functions
408 *
409 * Feature negotiation lists rely on and maintain the following invariants:
410 * - each feat_num in the list is known, i.e. we know its type and default value
411 * - each feat_num/is_local combination is unique (old entries are overwritten)
412 * - SP values are always freshly allocated
413 * - list is sorted in increasing order of feature number (faster lookup)
414 */
415static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
416 u8 feat_num, bool is_local)
417{
418 struct dccp_feat_entry *entry;
419
420 list_for_each_entry(entry, fn_list, node) {
421 if (entry->feat_num == feat_num && entry->is_local == is_local)
422 return entry;
423 else if (entry->feat_num > feat_num)
424 break;
425 }
426 return NULL;
427}
428
429/**
430 * dccp_feat_entry_new - Central list update routine (called by all others)
431 * @head: list to add to
432 * @feat: feature number
433 * @local: whether the local (1) or remote feature with number @feat is meant
434 * This is the only constructor and serves to ensure the above invariants.
435 */
436static struct dccp_feat_entry *
437 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
438{
439 struct dccp_feat_entry *entry;
440
441 list_for_each_entry(entry, head, node)
442 if (entry->feat_num == feat && entry->is_local == local) {
443 dccp_feat_val_destructor(entry->feat_num, &entry->val);
444 return entry;
445 } else if (entry->feat_num > feat) {
446 head = &entry->node;
447 break;
448 }
449
450 entry = kmalloc(sizeof(*entry), gfp_any());
451 if (entry != NULL) {
452 entry->feat_num = feat;
453 entry->is_local = local;
454 list_add_tail(&entry->node, head);
455 }
456 return entry;
457}
458
459/**
460 * dccp_feat_push_change - Add/overwrite a Change option in the list
461 * @fn_list: feature-negotiation list to update
462 * @feat: one of %dccp_feature_numbers
463 * @local: whether local (1) or remote (0) @feat_num is meant
464 * @needs_mandatory: whether to use Mandatory feature negotiation options
465 * @fval: pointer to NN/SP value to be inserted (will be copied)
466 */
467static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
468 u8 mandatory, dccp_feat_val *fval)
469{
470 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
471
472 if (new == NULL)
473 return -ENOMEM;
474
475 new->feat_num = feat;
476 new->is_local = local;
477 new->state = FEAT_INITIALISING;
478 new->needs_confirm = 0;
479 new->empty_confirm = 0;
480 new->val = *fval;
481 new->needs_mandatory = mandatory;
482
483 return 0;
484}
485
486/**
487 * dccp_feat_push_confirm - Add a Confirm entry to the FN list
488 * @fn_list: feature-negotiation list to add to
489 * @feat: one of %dccp_feature_numbers
490 * @local: whether local (1) or remote (0) @feat_num is being confirmed
491 * @fval: pointer to NN/SP value to be inserted or NULL
492 * Returns 0 on success, a Reset code for further processing otherwise.
493 */
494static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
495 dccp_feat_val *fval)
496{
497 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
498
499 if (new == NULL)
500 return DCCP_RESET_CODE_TOO_BUSY;
501
502 new->feat_num = feat;
503 new->is_local = local;
504 new->state = FEAT_STABLE; /* transition in 6.6.2 */
505 new->needs_confirm = 1;
506 new->empty_confirm = (fval == NULL);
507 new->val.nn = 0; /* zeroes the whole structure */
508 if (!new->empty_confirm)
509 new->val = *fval;
510 new->needs_mandatory = 0;
511
512 return 0;
513}
514
515static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
516{
517 return dccp_feat_push_confirm(fn_list, feat, local, NULL);
518}
519
520static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
521{
522 list_del(&entry->node);
523 dccp_feat_entry_destructor(entry);
524}
525
526void dccp_feat_list_purge(struct list_head *fn_list)
527{
528 struct dccp_feat_entry *entry, *next;
529
530 list_for_each_entry_safe(entry, next, fn_list, node)
531 dccp_feat_entry_destructor(entry);
532 INIT_LIST_HEAD(fn_list);
533}
534EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
535
536/* generate @to as full clone of @from - @to must not contain any nodes */
537int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
538{
539 struct dccp_feat_entry *entry, *new;
540
541 INIT_LIST_HEAD(to);
542 list_for_each_entry(entry, from, node) {
543 new = dccp_feat_clone_entry(entry);
544 if (new == NULL)
545 goto cloning_failed;
546 list_add_tail(&new->node, to);
547 }
548 return 0;
549
550cloning_failed:
551 dccp_feat_list_purge(to);
552 return -ENOMEM;
553}
554
555/**
556 * dccp_feat_valid_nn_length - Enforce length constraints on NN options
557 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
558 * incoming options are accepted as long as their values are valid.
559 */
560static u8 dccp_feat_valid_nn_length(u8 feat_num)
561{
562 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
563 return 2;
564 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
565 return 6;
566 return 0;
567}
568
569static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
570{
571 switch (feat_num) {
572 case DCCPF_ACK_RATIO:
573 return val <= DCCPF_ACK_RATIO_MAX;
574 case DCCPF_SEQUENCE_WINDOW:
575 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
576 }
577 return 0; /* feature unknown - so we can't tell */
578}
579
580/* check that SP values are within the ranges defined in RFC 4340 */
581static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
582{
583 switch (feat_num) {
584 case DCCPF_CCID:
585 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
586 /* Type-check Boolean feature values: */
587 case DCCPF_SHORT_SEQNOS:
588 case DCCPF_ECN_INCAPABLE:
589 case DCCPF_SEND_ACK_VECTOR:
590 case DCCPF_SEND_NDP_COUNT:
591 case DCCPF_DATA_CHECKSUM:
592 case DCCPF_SEND_LEV_RATE:
593 return val < 2;
594 case DCCPF_MIN_CSUM_COVER:
595 return val < 16;
596 }
597 return 0; /* feature unknown */
598}
599
600static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
601{
602 if (sp_list == NULL || sp_len < 1)
603 return 0;
604 while (sp_len--)
605 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
606 return 0;
607 return 1;
608}
609
610/**
611 * dccp_feat_insert_opts - Generate FN options from current list state
612 * @skb: next sk_buff to be sent to the peer
613 * @dp: for client during handshake and general negotiation
614 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
615 */
616int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
617 struct sk_buff *skb)
618{
619 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
620 struct dccp_feat_entry *pos, *next;
621 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
622 bool rpt;
623
624 /* put entries into @skb in the order they appear in the list */
625 list_for_each_entry_safe_reverse(pos, next, fn, node) {
626 opt = dccp_feat_genopt(pos);
627 type = dccp_feat_type(pos->feat_num);
628 rpt = false;
629
630 if (pos->empty_confirm) {
631 len = 0;
632 ptr = NULL;
633 } else {
634 if (type == FEAT_SP) {
635 len = pos->val.sp.len;
636 ptr = pos->val.sp.vec;
637 rpt = pos->needs_confirm;
638 } else if (type == FEAT_NN) {
639 len = dccp_feat_valid_nn_length(pos->feat_num);
640 ptr = nn_in_nbo;
641 dccp_encode_value_var(pos->val.nn, ptr, len);
642 } else {
643 DCCP_BUG("unknown feature %u", pos->feat_num);
644 return -1;
645 }
646 }
647 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
648
649 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
650 return -1;
651 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
652 return -1;
653 /*
654 * Enter CHANGING after transmitting the Change option (6.6.2).
655 */
656 if (pos->state == FEAT_INITIALISING)
657 pos->state = FEAT_CHANGING;
658 }
659 return 0;
660}
661
662/**
663 * __feat_register_nn - Register new NN value on socket
664 * @fn: feature-negotiation list to register with
665 * @feat: an NN feature from %dccp_feature_numbers
666 * @mandatory: use Mandatory option if 1
667 * @nn_val: value to register (restricted to 4 bytes)
668 * Note that NN features are local by definition (RFC 4340, 6.3.2).
669 */
670static int __feat_register_nn(struct list_head *fn, u8 feat,
671 u8 mandatory, u64 nn_val)
672{
673 dccp_feat_val fval = { .nn = nn_val };
674
675 if (dccp_feat_type(feat) != FEAT_NN ||
676 !dccp_feat_is_valid_nn_val(feat, nn_val))
677 return -EINVAL;
678
679 /* Don't bother with default values, they will be activated anyway. */
680 if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
681 return 0;
682
683 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
684}
685
686/**
687 * __feat_register_sp - Register new SP value/list on socket
688 * @fn: feature-negotiation list to register with
689 * @feat: an SP feature from %dccp_feature_numbers
690 * @is_local: whether the local (1) or the remote (0) @feat is meant
691 * @mandatory: use Mandatory option if 1
692 * @sp_val: SP value followed by optional preference list
693 * @sp_len: length of @sp_val in bytes
694 */
695static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
696 u8 mandatory, u8 const *sp_val, u8 sp_len)
697{
698 dccp_feat_val fval;
699
700 if (dccp_feat_type(feat) != FEAT_SP ||
701 !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
702 return -EINVAL;
703
704 /* Avoid negotiating alien CCIDs by only advertising supported ones */
705 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
706 return -EOPNOTSUPP;
707
708 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
709 return -ENOMEM;
710
711 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
712}
713
714/**
715 * dccp_feat_register_sp - Register requests to change SP feature values
716 * @sk: client or listening socket
717 * @feat: one of %dccp_feature_numbers
718 * @is_local: whether the local (1) or remote (0) @feat is meant
719 * @list: array of preferred values, in descending order of preference
720 * @len: length of @list in bytes
721 */
722int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
723 u8 const *list, u8 len)
724{ /* any changes must be registered before establishing the connection */
725 if (sk->sk_state != DCCP_CLOSED)
726 return -EISCONN;
727 if (dccp_feat_type(feat) != FEAT_SP)
728 return -EINVAL;
729 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
730 0, list, len);
731}
732
733
734/*
735 * Tracking features whose value depend on the choice of CCID
736 *
737 * This is designed with an extension in mind so that a list walk could be done
738 * before activating any features. However, the existing framework was found to
739 * work satisfactorily up until now, the automatic verification is left open.
740 * When adding new CCIDs, add a corresponding dependency table here.
741 */
742static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
743{
744 static const struct ccid_dependency ccid2_dependencies[2][2] = {
745 /*
746 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
747 * feature and Send Ack Vector is an RX feature, `is_local'
748 * needs to be reversed.
749 */
750 { /* Dependencies of the receiver-side (remote) CCID2 */
751 {
752 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
753 .is_local = true,
754 .is_mandatory = true,
755 .val = 1
756 },
757 { 0, 0, 0, 0 }
758 },
759 { /* Dependencies of the sender-side (local) CCID2 */
760 {
761 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
762 .is_local = false,
763 .is_mandatory = true,
764 .val = 1
765 },
766 { 0, 0, 0, 0 }
767 }
768 };
769 static const struct ccid_dependency ccid3_dependencies[2][5] = {
770 { /*
771 * Dependencies of the receiver-side CCID3
772 */
773 { /* locally disable Ack Vectors */
774 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
775 .is_local = true,
776 .is_mandatory = false,
777 .val = 0
778 },
779 { /* see below why Send Loss Event Rate is on */
780 .dependent_feat = DCCPF_SEND_LEV_RATE,
781 .is_local = true,
782 .is_mandatory = true,
783 .val = 1
784 },
785 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
786 .dependent_feat = DCCPF_SEND_NDP_COUNT,
787 .is_local = false,
788 .is_mandatory = true,
789 .val = 1
790 },
791 { 0, 0, 0, 0 },
792 },
793 { /*
794 * CCID3 at the TX side: we request that the HC-receiver
795 * will not send Ack Vectors (they will be ignored, so
796 * Mandatory is not set); we enable Send Loss Event Rate
797 * (Mandatory since the implementation does not support
798 * the Loss Intervals option of RFC 4342, 8.6).
799 * The last two options are for peer's information only.
800 */
801 {
802 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
803 .is_local = false,
804 .is_mandatory = false,
805 .val = 0
806 },
807 {
808 .dependent_feat = DCCPF_SEND_LEV_RATE,
809 .is_local = false,
810 .is_mandatory = true,
811 .val = 1
812 },
813 { /* this CCID does not support Ack Ratio */
814 .dependent_feat = DCCPF_ACK_RATIO,
815 .is_local = true,
816 .is_mandatory = false,
817 .val = 0
818 },
819 { /* tell receiver we are sending NDP counts */
820 .dependent_feat = DCCPF_SEND_NDP_COUNT,
821 .is_local = true,
822 .is_mandatory = false,
823 .val = 1
824 },
825 { 0, 0, 0, 0 }
826 }
827 };
828 switch (ccid) {
829 case DCCPC_CCID2:
830 return ccid2_dependencies[is_local];
831 case DCCPC_CCID3:
832 return ccid3_dependencies[is_local];
833 default:
834 return NULL;
835 }
836}
837
838/**
839 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
840 * @fn: feature-negotiation list to update
841 * @id: CCID number to track
842 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
843 * This function needs to be called after registering all other features.
844 */
845static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
846{
847 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
848 int i, rc = (table == NULL);
849
850 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
851 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
852 rc = __feat_register_sp(fn, table[i].dependent_feat,
853 table[i].is_local,
854 table[i].is_mandatory,
855 &table[i].val, 1);
856 else
857 rc = __feat_register_nn(fn, table[i].dependent_feat,
858 table[i].is_mandatory,
859 table[i].val);
860 return rc;
861}
862
863/**
864 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
865 * @dp: client or listening socket (settings will be inherited)
866 * This is called after all registrations (socket initialisation, sysctls, and
867 * sockopt calls), and before sending the first packet containing Change options
868 * (ie. client-Request or server-Response), to ensure internal consistency.
869 */
870int dccp_feat_finalise_settings(struct dccp_sock *dp)
871{
872 struct list_head *fn = &dp->dccps_featneg;
873 struct dccp_feat_entry *entry;
874 int i = 2, ccids[2] = { -1, -1 };
875
876 /*
877 * Propagating CCIDs:
878 * 1) not useful to propagate CCID settings if this host advertises more
879 * than one CCID: the choice of CCID may still change - if this is
880 * the client, or if this is the server and the client sends
881 * singleton CCID values.
882 * 2) since is that propagate_ccid changes the list, we defer changing
883 * the sorted list until after the traversal.
884 */
885 list_for_each_entry(entry, fn, node)
886 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
887 ccids[entry->is_local] = entry->val.sp.vec[0];
888 while (i--)
889 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
890 return -1;
891 dccp_feat_print_fnlist(fn);
892 return 0;
893}
894
895/**
896 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
897 * It is the server which resolves the dependencies once the CCID has been
898 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
899 */
900int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
901{
902 struct list_head *fn = &dreq->dreq_featneg;
903 struct dccp_feat_entry *entry;
904 u8 is_local, ccid;
905
906 for (is_local = 0; is_local <= 1; is_local++) {
907 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
908
909 if (entry != NULL && !entry->empty_confirm)
910 ccid = entry->val.sp.vec[0];
911 else
912 ccid = dccp_feat_default_value(DCCPF_CCID);
913
914 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
915 return -1;
916 }
917 return 0;
918}
919
920/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
921static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
922{
923 u8 c, s;
924
925 for (s = 0; s < slen; s++)
926 for (c = 0; c < clen; c++)
927 if (servlist[s] == clilist[c])
928 return servlist[s];
929 return -1;
930}
931
932/**
933 * dccp_feat_prefer - Move preferred entry to the start of array
934 * Reorder the @array_len elements in @array so that @preferred_value comes
935 * first. Returns >0 to indicate that @preferred_value does occur in @array.
936 */
937static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
938{
939 u8 i, does_occur = 0;
940
941 if (array != NULL) {
942 for (i = 0; i < array_len; i++)
943 if (array[i] == preferred_value) {
944 array[i] = array[0];
945 does_occur++;
946 }
947 if (does_occur)
948 array[0] = preferred_value;
949 }
950 return does_occur;
951}
952
953/**
954 * dccp_feat_reconcile - Reconcile SP preference lists
955 * @fval: SP list to reconcile into
956 * @arr: received SP preference list
957 * @len: length of @arr in bytes
958 * @is_server: whether this side is the server (and @fv is the server's list)
959 * @reorder: whether to reorder the list in @fv after reconciling with @arr
960 * When successful, > 0 is returned and the reconciled list is in @fval.
961 * A value of 0 means that negotiation failed (no shared entry).
962 */
963static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
964 bool is_server, bool reorder)
965{
966 int rc;
967
968 if (!fv->sp.vec || !arr) {
969 DCCP_CRIT("NULL feature value or array");
970 return 0;
971 }
972
973 if (is_server)
974 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
975 else
976 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
977
978 if (!reorder)
979 return rc;
980 if (rc < 0)
981 return 0;
982
983 /*
984 * Reorder list: used for activating features and in dccp_insert_fn_opt.
985 */
986 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
987}
988
989/**
990 * dccp_feat_change_recv - Process incoming ChangeL/R options
991 * @fn: feature-negotiation list to update
992 * @is_mandatory: whether the Change was preceded by a Mandatory option
993 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
994 * @feat: one of %dccp_feature_numbers
995 * @val: NN value or SP value/preference list
996 * @len: length of @val in bytes
997 * @server: whether this node is the server (1) or the client (0)
998 */
999static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1000 u8 feat, u8 *val, u8 len, const bool server)
1001{
1002 u8 defval, type = dccp_feat_type(feat);
1003 const bool local = (opt == DCCPO_CHANGE_R);
1004 struct dccp_feat_entry *entry;
1005 dccp_feat_val fval;
1006
1007 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
1008 goto unknown_feature_or_value;
1009
1010 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1011
1012 /*
1013 * Negotiation of NN features: Change R is invalid, so there is no
1014 * simultaneous negotiation; hence we do not look up in the list.
1015 */
1016 if (type == FEAT_NN) {
1017 if (local || len > sizeof(fval.nn))
1018 goto unknown_feature_or_value;
1019
1020 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1021 fval.nn = dccp_decode_value_var(val, len);
1022 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1023 goto unknown_feature_or_value;
1024
1025 return dccp_feat_push_confirm(fn, feat, local, &fval);
1026 }
1027
1028 /*
1029 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
1030 */
1031 entry = dccp_feat_list_lookup(fn, feat, local);
1032 if (entry == NULL) {
1033 /*
1034 * No particular preferences have been registered. We deal with
1035 * this situation by assuming that all valid values are equally
1036 * acceptable, and apply the following checks:
1037 * - if the peer's list is a singleton, we accept a valid value;
1038 * - if we are the server, we first try to see if the peer (the
1039 * client) advertises the default value. If yes, we use it,
1040 * otherwise we accept the preferred value;
1041 * - else if we are the client, we use the first list element.
1042 */
1043 if (dccp_feat_clone_sp_val(&fval, val, 1))
1044 return DCCP_RESET_CODE_TOO_BUSY;
1045
1046 if (len > 1 && server) {
1047 defval = dccp_feat_default_value(feat);
1048 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1049 fval.sp.vec[0] = defval;
1050 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1051 kfree(fval.sp.vec);
1052 goto unknown_feature_or_value;
1053 }
1054
1055 /* Treat unsupported CCIDs like invalid values */
1056 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1057 kfree(fval.sp.vec);
1058 goto not_valid_or_not_known;
1059 }
1060
1061 return dccp_feat_push_confirm(fn, feat, local, &fval);
1062
1063 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
1064 return 0;
1065 }
1066
1067 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1068 entry->empty_confirm = 0;
1069 } else if (is_mandatory) {
1070 return DCCP_RESET_CODE_MANDATORY_ERROR;
1071 } else if (entry->state == FEAT_INITIALISING) {
1072 /*
1073 * Failed simultaneous negotiation (server only): try to `save'
1074 * the connection by checking whether entry contains the default
1075 * value for @feat. If yes, send an empty Confirm to signal that
1076 * the received Change was not understood - which implies using
1077 * the default value.
1078 * If this also fails, we use Reset as the last resort.
1079 */
1080 WARN_ON(!server);
1081 defval = dccp_feat_default_value(feat);
1082 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1083 return DCCP_RESET_CODE_OPTION_ERROR;
1084 entry->empty_confirm = 1;
1085 }
1086 entry->needs_confirm = 1;
1087 entry->needs_mandatory = 0;
1088 entry->state = FEAT_STABLE;
1089 return 0;
1090
1091unknown_feature_or_value:
1092 if (!is_mandatory)
1093 return dccp_push_empty_confirm(fn, feat, local);
1094
1095not_valid_or_not_known:
1096 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1097 : DCCP_RESET_CODE_OPTION_ERROR;
1098}
1099
1100/**
1101 * dccp_feat_confirm_recv - Process received Confirm options
1102 * @fn: feature-negotiation list to update
1103 * @is_mandatory: whether @opt was preceded by a Mandatory option
1104 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
1105 * @feat: one of %dccp_feature_numbers
1106 * @val: NN value or SP value/preference list
1107 * @len: length of @val in bytes
1108 * @server: whether this node is server (1) or client (0)
1109 */
1110static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1111 u8 feat, u8 *val, u8 len, const bool server)
1112{
1113 u8 *plist, plen, type = dccp_feat_type(feat);
1114 const bool local = (opt == DCCPO_CONFIRM_R);
1115 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1116
1117 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1118
1119 if (entry == NULL) { /* nothing queued: ignore or handle error */
1120 if (is_mandatory && type == FEAT_UNKNOWN)
1121 return DCCP_RESET_CODE_MANDATORY_ERROR;
1122
1123 if (!local && type == FEAT_NN) /* 6.3.2 */
1124 goto confirmation_failed;
1125 return 0;
1126 }
1127
1128 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1129 return 0;
1130
1131 if (len == 0) {
1132 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1133 goto confirmation_failed;
1134 /*
1135 * Empty Confirm during connection setup: this means reverting
1136 * to the `old' value, which in this case is the default. Since
1137 * we handle default values automatically when no other values
1138 * have been set, we revert to the old value by removing this
1139 * entry from the list.
1140 */
1141 dccp_feat_list_pop(entry);
1142 return 0;
1143 }
1144
1145 if (type == FEAT_NN) {
1146 if (len > sizeof(entry->val.nn))
1147 goto confirmation_failed;
1148
1149 if (entry->val.nn == dccp_decode_value_var(val, len))
1150 goto confirmation_succeeded;
1151
1152 DCCP_WARN("Bogus Confirm for non-existing value\n");
1153 goto confirmation_failed;
1154 }
1155
1156 /*
1157 * Parsing SP Confirms: the first element of @val is the preferred
1158 * SP value which the peer confirms, the remainder depends on @len.
1159 * Note that only the confirmed value need to be a valid SP value.
1160 */
1161 if (!dccp_feat_is_valid_sp_val(feat, *val))
1162 goto confirmation_failed;
1163
1164 if (len == 1) { /* peer didn't supply a preference list */
1165 plist = val;
1166 plen = len;
1167 } else { /* preferred value + preference list */
1168 plist = val + 1;
1169 plen = len - 1;
1170 }
1171
1172 /* Check whether the peer got the reconciliation right (6.6.8) */
1173 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1174 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1175 return DCCP_RESET_CODE_OPTION_ERROR;
1176 }
1177 entry->val.sp.vec[0] = *val;
1178
1179confirmation_succeeded:
1180 entry->state = FEAT_STABLE;
1181 return 0;
1182
1183confirmation_failed:
1184 DCCP_WARN("Confirmation failed\n");
1185 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1186 : DCCP_RESET_CODE_OPTION_ERROR;
1187}
1188
1189/**
1190 * dccp_feat_parse_options - Process Feature-Negotiation Options
1191 * @sk: for general use and used by the client during connection setup
1192 * @dreq: used by the server during connection setup
1193 * @mandatory: whether @opt was preceded by a Mandatory option
1194 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1195 * @feat: one of %dccp_feature_numbers
1196 * @val: value contents of @opt
1197 * @len: length of @val in bytes
1198 * Returns 0 on success, a Reset code for ending the connection otherwise.
1199 */
1200int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1201 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1202{
1203 struct dccp_sock *dp = dccp_sk(sk);
1204 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1205 bool server = false;
1206
1207 switch (sk->sk_state) {
1208 /*
1209 * Negotiation during connection setup
1210 */
1211 case DCCP_LISTEN:
1212 server = true; /* fall through */
1213 case DCCP_REQUESTING:
1214 switch (opt) {
1215 case DCCPO_CHANGE_L:
1216 case DCCPO_CHANGE_R:
1217 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1218 val, len, server);
1219 case DCCPO_CONFIRM_R:
1220 case DCCPO_CONFIRM_L:
1221 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1222 val, len, server);
1223 }
1224 }
1225 return 0; /* ignore FN options in all other states */
1226}
1227
1228/**
1229 * dccp_feat_init - Seed feature negotiation with host-specific defaults
1230 * This initialises global defaults, depending on the value of the sysctls.
1231 * These can later be overridden by registering changes via setsockopt calls.
1232 * The last link in the chain is finalise_settings, to make sure that between
1233 * here and the start of actual feature negotiation no inconsistencies enter.
1234 *
1235 * All features not appearing below use either defaults or are otherwise
1236 * later adjusted through dccp_feat_finalise_settings().
1237 */
1238int dccp_feat_init(struct sock *sk)
1239{
1240 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1241 u8 on = 1, off = 0;
1242 int rc;
1243 struct {
1244 u8 *val;
1245 u8 len;
1246 } tx, rx;
1247
1248 /* Non-negotiable (NN) features */
1249 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
1250 sysctl_dccp_sequence_window);
1251 if (rc)
1252 return rc;
1253
1254 /* Server-priority (SP) features */
1255
1256 /* Advertise that short seqnos are not supported (7.6.1) */
1257 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
1258 if (rc)
1259 return rc;
1260
1261 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
1262 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
1263 if (rc)
1264 return rc;
1265
1266 /*
1267 * We advertise the available list of CCIDs and reorder according to
1268 * preferences, to avoid failure resulting from negotiating different
1269 * singleton values (which always leads to failure).
1270 * These settings can still (later) be overridden via sockopts.
1271 */
1272 if (ccid_get_builtin_ccids(&tx.val, &tx.len) ||
1273 ccid_get_builtin_ccids(&rx.val, &rx.len))
1274 return -ENOBUFS;
1275
1276 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
1277 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
1278 goto free_ccid_lists;
1279
1280 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
1281 if (rc)
1282 goto free_ccid_lists;
1283
1284 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
1285
1286free_ccid_lists:
1287 kfree(tx.val);
1288 kfree(rx.val);
1289 return rc;
1290}
1291
1292int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1293{
1294 struct dccp_sock *dp = dccp_sk(sk);
1295 struct dccp_feat_entry *cur, *next;
1296 int idx;
1297 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1298 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1299 };
1300
1301 list_for_each_entry(cur, fn_list, node) {
1302 /*
1303 * An empty Confirm means that either an unknown feature type
1304 * or an invalid value was present. In the first case there is
1305 * nothing to activate, in the other the default value is used.
1306 */
1307 if (cur->empty_confirm)
1308 continue;
1309
1310 idx = dccp_feat_index(cur->feat_num);
1311 if (idx < 0) {
1312 DCCP_BUG("Unknown feature %u", cur->feat_num);
1313 goto activation_failed;
1314 }
1315 if (cur->state != FEAT_STABLE) {
1316 DCCP_CRIT("Negotiation of %s %s failed in state %s",
1317 cur->is_local ? "local" : "remote",
1318 dccp_feat_fname(cur->feat_num),
1319 dccp_feat_sname[cur->state]);
1320 goto activation_failed;
1321 }
1322 fvals[idx][cur->is_local] = &cur->val;
1323 }
1324
1325 /*
1326 * Activate in decreasing order of index, so that the CCIDs are always
1327 * activated as the last feature. This avoids the case where a CCID
1328 * relies on the initialisation of one or more features that it depends
1329 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1330 */
1331 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1332 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1333 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1334 DCCP_CRIT("Could not activate %d", idx);
1335 goto activation_failed;
1336 }
1337
1338 /* Clean up Change options which have been confirmed already */
1339 list_for_each_entry_safe(cur, next, fn_list, node)
1340 if (!cur->needs_confirm)
1341 dccp_feat_list_pop(cur);
1342
1343 dccp_pr_debug("Activation OK\n");
1344 return 0;
1345
1346activation_failed:
1347 /*
1348 * We clean up everything that may have been allocated, since
1349 * it is difficult to track at which stage negotiation failed.
1350 * This is ok, since all allocation functions below are robust
1351 * against NULL arguments.
1352 */
1353 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1354 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1355 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1356 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1357 dp->dccps_hc_rx_ackvec = NULL;
1358 return -1;
1359}
1/*
2 * net/dccp/feat.c
3 *
4 * Feature negotiation for the DCCP protocol (RFC 4340, section 6)
5 *
6 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
7 * Rewrote from scratch, some bits from earlier code by
8 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
9 *
10 *
11 * ASSUMPTIONS
12 * -----------
13 * o Feature negotiation is coordinated with connection setup (as in TCP), wild
14 * changes of parameters of an established connection are not supported.
15 * o Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN.
16 * o All currently known SP features have 1-byte quantities. If in the future
17 * extensions of RFCs 4340..42 define features with item lengths larger than
18 * one byte, a feature-specific extension of the code will be required.
19 *
20 * This program is free software; you can redistribute it and/or
21 * modify it under the terms of the GNU General Public License
22 * as published by the Free Software Foundation; either version
23 * 2 of the License, or (at your option) any later version.
24 */
25#include <linux/module.h>
26#include <linux/slab.h>
27#include "ccid.h"
28#include "feat.h"
29
30/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
31unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
32int sysctl_dccp_rx_ccid __read_mostly = 2,
33 sysctl_dccp_tx_ccid __read_mostly = 2;
34
35/*
36 * Feature activation handlers.
37 *
38 * These all use an u64 argument, to provide enough room for NN/SP features. At
39 * this stage the negotiated values have been checked to be within their range.
40 */
41static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
42{
43 struct dccp_sock *dp = dccp_sk(sk);
44 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
45
46 if (new_ccid == NULL)
47 return -ENOMEM;
48
49 if (rx) {
50 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
51 dp->dccps_hc_rx_ccid = new_ccid;
52 } else {
53 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
54 dp->dccps_hc_tx_ccid = new_ccid;
55 }
56 return 0;
57}
58
59static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
60{
61 struct dccp_sock *dp = dccp_sk(sk);
62
63 if (rx) {
64 dp->dccps_r_seq_win = seq_win;
65 /* propagate changes to update SWL/SWH */
66 dccp_update_gsr(sk, dp->dccps_gsr);
67 } else {
68 dp->dccps_l_seq_win = seq_win;
69 /* propagate changes to update AWL */
70 dccp_update_gss(sk, dp->dccps_gss);
71 }
72 return 0;
73}
74
75static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
76{
77 if (rx)
78 dccp_sk(sk)->dccps_r_ack_ratio = ratio;
79 else
80 dccp_sk(sk)->dccps_l_ack_ratio = ratio;
81 return 0;
82}
83
84static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
85{
86 struct dccp_sock *dp = dccp_sk(sk);
87
88 if (rx) {
89 if (enable && dp->dccps_hc_rx_ackvec == NULL) {
90 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
91 if (dp->dccps_hc_rx_ackvec == NULL)
92 return -ENOMEM;
93 } else if (!enable) {
94 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
95 dp->dccps_hc_rx_ackvec = NULL;
96 }
97 }
98 return 0;
99}
100
101static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
102{
103 if (!rx)
104 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
105 return 0;
106}
107
108/*
109 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
110 * `rx' holds when the sending peer informs about his partial coverage via a
111 * ChangeR() option. In the other case, we are the sender and the receiver
112 * announces its coverage via ChangeL() options. The policy here is to honour
113 * such communication by enabling the corresponding partial coverage - but only
114 * if it has not been set manually before; the warning here means that all
115 * packets will be dropped.
116 */
117static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
118{
119 struct dccp_sock *dp = dccp_sk(sk);
120
121 if (rx)
122 dp->dccps_pcrlen = cscov;
123 else {
124 if (dp->dccps_pcslen == 0)
125 dp->dccps_pcslen = cscov;
126 else if (cscov > dp->dccps_pcslen)
127 DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
128 dp->dccps_pcslen, (u8)cscov);
129 }
130 return 0;
131}
132
133static const struct {
134 u8 feat_num; /* DCCPF_xxx */
135 enum dccp_feat_type rxtx; /* RX or TX */
136 enum dccp_feat_type reconciliation; /* SP or NN */
137 u8 default_value; /* as in 6.4 */
138 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
139/*
140 * Lookup table for location and type of features (from RFC 4340/4342)
141 * +--------------------------+----+-----+----+----+---------+-----------+
142 * | Feature | Location | Reconc. | Initial | Section |
143 * | | RX | TX | SP | NN | Value | Reference |
144 * +--------------------------+----+-----+----+----+---------+-----------+
145 * | DCCPF_CCID | | X | X | | 2 | 10 |
146 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
147 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
148 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
149 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
150 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
151 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
152 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
153 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
154 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
155 * +--------------------------+----+-----+----+----+---------+-----------+
156 */
157} dccp_feat_table[] = {
158 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
159 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
160 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
161 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
162 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
163 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
164 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
165 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
166 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
167 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
168};
169#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
170
171/**
172 * dccp_feat_index - Hash function to map feature number into array position
173 * Returns consecutive array index or -1 if the feature is not understood.
174 */
175static int dccp_feat_index(u8 feat_num)
176{
177 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
178 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
179 return feat_num - 1;
180
181 /*
182 * Other features: add cases for new feature types here after adding
183 * them to the above table.
184 */
185 switch (feat_num) {
186 case DCCPF_SEND_LEV_RATE:
187 return DCCP_FEAT_SUPPORTED_MAX - 1;
188 }
189 return -1;
190}
191
192static u8 dccp_feat_type(u8 feat_num)
193{
194 int idx = dccp_feat_index(feat_num);
195
196 if (idx < 0)
197 return FEAT_UNKNOWN;
198 return dccp_feat_table[idx].reconciliation;
199}
200
201static int dccp_feat_default_value(u8 feat_num)
202{
203 int idx = dccp_feat_index(feat_num);
204 /*
205 * There are no default values for unknown features, so encountering a
206 * negative index here indicates a serious problem somewhere else.
207 */
208 DCCP_BUG_ON(idx < 0);
209
210 return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
211}
212
213/*
214 * Debugging and verbose-printing section
215 */
216static const char *dccp_feat_fname(const u8 feat)
217{
218 static const char *const feature_names[] = {
219 [DCCPF_RESERVED] = "Reserved",
220 [DCCPF_CCID] = "CCID",
221 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
222 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
223 [DCCPF_ECN_INCAPABLE] = "ECN Incapable",
224 [DCCPF_ACK_RATIO] = "Ack Ratio",
225 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
226 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
227 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
228 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
229 };
230 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
231 return feature_names[DCCPF_RESERVED];
232
233 if (feat == DCCPF_SEND_LEV_RATE)
234 return "Send Loss Event Rate";
235 if (feat >= DCCPF_MIN_CCID_SPECIFIC)
236 return "CCID-specific";
237
238 return feature_names[feat];
239}
240
241static const char *const dccp_feat_sname[] = {
242 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
243};
244
245#ifdef CONFIG_IP_DCCP_DEBUG
246static const char *dccp_feat_oname(const u8 opt)
247{
248 switch (opt) {
249 case DCCPO_CHANGE_L: return "Change_L";
250 case DCCPO_CONFIRM_L: return "Confirm_L";
251 case DCCPO_CHANGE_R: return "Change_R";
252 case DCCPO_CONFIRM_R: return "Confirm_R";
253 }
254 return NULL;
255}
256
257static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val)
258{
259 u8 i, type = dccp_feat_type(feat_num);
260
261 if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL))
262 dccp_pr_debug_cat("(NULL)");
263 else if (type == FEAT_SP)
264 for (i = 0; i < val->sp.len; i++)
265 dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]);
266 else if (type == FEAT_NN)
267 dccp_pr_debug_cat("%llu", (unsigned long long)val->nn);
268 else
269 dccp_pr_debug_cat("unknown type %u", type);
270}
271
272static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len)
273{
274 u8 type = dccp_feat_type(feat_num);
275 dccp_feat_val fval = { .sp.vec = list, .sp.len = len };
276
277 if (type == FEAT_NN)
278 fval.nn = dccp_decode_value_var(list, len);
279 dccp_feat_printval(feat_num, &fval);
280}
281
282static void dccp_feat_print_entry(struct dccp_feat_entry const *entry)
283{
284 dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote",
285 dccp_feat_fname(entry->feat_num));
286 dccp_feat_printval(entry->feat_num, &entry->val);
287 dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state],
288 entry->needs_confirm ? "(Confirm pending)" : "");
289}
290
291#define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \
292 dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\
293 dccp_feat_printvals(feat, val, len); \
294 dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0)
295
296#define dccp_feat_print_fnlist(fn_list) { \
297 const struct dccp_feat_entry *___entry; \
298 \
299 dccp_pr_debug("List Dump:\n"); \
300 list_for_each_entry(___entry, fn_list, node) \
301 dccp_feat_print_entry(___entry); \
302}
303#else /* ! CONFIG_IP_DCCP_DEBUG */
304#define dccp_feat_print_opt(opt, feat, val, len, mandatory)
305#define dccp_feat_print_fnlist(fn_list)
306#endif
307
308static int __dccp_feat_activate(struct sock *sk, const int idx,
309 const bool is_local, dccp_feat_val const *fval)
310{
311 bool rx;
312 u64 val;
313
314 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
315 return -1;
316 if (dccp_feat_table[idx].activation_hdlr == NULL)
317 return 0;
318
319 if (fval == NULL) {
320 val = dccp_feat_table[idx].default_value;
321 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
322 if (fval->sp.vec == NULL) {
323 /*
324 * This can happen when an empty Confirm is sent
325 * for an SP (i.e. known) feature. In this case
326 * we would be using the default anyway.
327 */
328 DCCP_CRIT("Feature #%d undefined: using default", idx);
329 val = dccp_feat_table[idx].default_value;
330 } else {
331 val = fval->sp.vec[0];
332 }
333 } else {
334 val = fval->nn;
335 }
336
337 /* Location is RX if this is a local-RX or remote-TX feature */
338 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
339
340 dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX",
341 dccp_feat_fname(dccp_feat_table[idx].feat_num),
342 fval ? "" : "default ", (unsigned long long)val);
343
344 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
345}
346
347/**
348 * dccp_feat_activate - Activate feature value on socket
349 * @sk: fully connected DCCP socket (after handshake is complete)
350 * @feat_num: feature to activate, one of %dccp_feature_numbers
351 * @local: whether local (1) or remote (0) @feat_num is meant
352 * @fval: the value (SP or NN) to activate, or NULL to use the default value
353 * For general use this function is preferable over __dccp_feat_activate().
354 */
355static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
356 dccp_feat_val const *fval)
357{
358 return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
359}
360
361/* Test for "Req'd" feature (RFC 4340, 6.4) */
362static inline int dccp_feat_must_be_understood(u8 feat_num)
363{
364 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
365 feat_num == DCCPF_SEQUENCE_WINDOW;
366}
367
368/* copy constructor, fval must not already contain allocated memory */
369static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
370{
371 fval->sp.len = len;
372 if (fval->sp.len > 0) {
373 fval->sp.vec = kmemdup(val, len, gfp_any());
374 if (fval->sp.vec == NULL) {
375 fval->sp.len = 0;
376 return -ENOBUFS;
377 }
378 }
379 return 0;
380}
381
382static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
383{
384 if (unlikely(val == NULL))
385 return;
386 if (dccp_feat_type(feat_num) == FEAT_SP)
387 kfree(val->sp.vec);
388 memset(val, 0, sizeof(*val));
389}
390
391static struct dccp_feat_entry *
392 dccp_feat_clone_entry(struct dccp_feat_entry const *original)
393{
394 struct dccp_feat_entry *new;
395 u8 type = dccp_feat_type(original->feat_num);
396
397 if (type == FEAT_UNKNOWN)
398 return NULL;
399
400 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
401 if (new == NULL)
402 return NULL;
403
404 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
405 original->val.sp.vec,
406 original->val.sp.len)) {
407 kfree(new);
408 return NULL;
409 }
410 return new;
411}
412
413static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
414{
415 if (entry != NULL) {
416 dccp_feat_val_destructor(entry->feat_num, &entry->val);
417 kfree(entry);
418 }
419}
420
421/*
422 * List management functions
423 *
424 * Feature negotiation lists rely on and maintain the following invariants:
425 * - each feat_num in the list is known, i.e. we know its type and default value
426 * - each feat_num/is_local combination is unique (old entries are overwritten)
427 * - SP values are always freshly allocated
428 * - list is sorted in increasing order of feature number (faster lookup)
429 */
430static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
431 u8 feat_num, bool is_local)
432{
433 struct dccp_feat_entry *entry;
434
435 list_for_each_entry(entry, fn_list, node) {
436 if (entry->feat_num == feat_num && entry->is_local == is_local)
437 return entry;
438 else if (entry->feat_num > feat_num)
439 break;
440 }
441 return NULL;
442}
443
444/**
445 * dccp_feat_entry_new - Central list update routine (called by all others)
446 * @head: list to add to
447 * @feat: feature number
448 * @local: whether the local (1) or remote feature with number @feat is meant
449 * This is the only constructor and serves to ensure the above invariants.
450 */
451static struct dccp_feat_entry *
452 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
453{
454 struct dccp_feat_entry *entry;
455
456 list_for_each_entry(entry, head, node)
457 if (entry->feat_num == feat && entry->is_local == local) {
458 dccp_feat_val_destructor(entry->feat_num, &entry->val);
459 return entry;
460 } else if (entry->feat_num > feat) {
461 head = &entry->node;
462 break;
463 }
464
465 entry = kmalloc(sizeof(*entry), gfp_any());
466 if (entry != NULL) {
467 entry->feat_num = feat;
468 entry->is_local = local;
469 list_add_tail(&entry->node, head);
470 }
471 return entry;
472}
473
474/**
475 * dccp_feat_push_change - Add/overwrite a Change option in the list
476 * @fn_list: feature-negotiation list to update
477 * @feat: one of %dccp_feature_numbers
478 * @local: whether local (1) or remote (0) @feat_num is meant
479 * @needs_mandatory: whether to use Mandatory feature negotiation options
480 * @fval: pointer to NN/SP value to be inserted (will be copied)
481 */
482static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
483 u8 mandatory, dccp_feat_val *fval)
484{
485 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
486
487 if (new == NULL)
488 return -ENOMEM;
489
490 new->feat_num = feat;
491 new->is_local = local;
492 new->state = FEAT_INITIALISING;
493 new->needs_confirm = false;
494 new->empty_confirm = false;
495 new->val = *fval;
496 new->needs_mandatory = mandatory;
497
498 return 0;
499}
500
501/**
502 * dccp_feat_push_confirm - Add a Confirm entry to the FN list
503 * @fn_list: feature-negotiation list to add to
504 * @feat: one of %dccp_feature_numbers
505 * @local: whether local (1) or remote (0) @feat_num is being confirmed
506 * @fval: pointer to NN/SP value to be inserted or NULL
507 * Returns 0 on success, a Reset code for further processing otherwise.
508 */
509static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
510 dccp_feat_val *fval)
511{
512 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
513
514 if (new == NULL)
515 return DCCP_RESET_CODE_TOO_BUSY;
516
517 new->feat_num = feat;
518 new->is_local = local;
519 new->state = FEAT_STABLE; /* transition in 6.6.2 */
520 new->needs_confirm = true;
521 new->empty_confirm = (fval == NULL);
522 new->val.nn = 0; /* zeroes the whole structure */
523 if (!new->empty_confirm)
524 new->val = *fval;
525 new->needs_mandatory = false;
526
527 return 0;
528}
529
530static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
531{
532 return dccp_feat_push_confirm(fn_list, feat, local, NULL);
533}
534
535static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
536{
537 list_del(&entry->node);
538 dccp_feat_entry_destructor(entry);
539}
540
541void dccp_feat_list_purge(struct list_head *fn_list)
542{
543 struct dccp_feat_entry *entry, *next;
544
545 list_for_each_entry_safe(entry, next, fn_list, node)
546 dccp_feat_entry_destructor(entry);
547 INIT_LIST_HEAD(fn_list);
548}
549EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
550
551/* generate @to as full clone of @from - @to must not contain any nodes */
552int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
553{
554 struct dccp_feat_entry *entry, *new;
555
556 INIT_LIST_HEAD(to);
557 list_for_each_entry(entry, from, node) {
558 new = dccp_feat_clone_entry(entry);
559 if (new == NULL)
560 goto cloning_failed;
561 list_add_tail(&new->node, to);
562 }
563 return 0;
564
565cloning_failed:
566 dccp_feat_list_purge(to);
567 return -ENOMEM;
568}
569
570/**
571 * dccp_feat_valid_nn_length - Enforce length constraints on NN options
572 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
573 * incoming options are accepted as long as their values are valid.
574 */
575static u8 dccp_feat_valid_nn_length(u8 feat_num)
576{
577 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
578 return 2;
579 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
580 return 6;
581 return 0;
582}
583
584static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
585{
586 switch (feat_num) {
587 case DCCPF_ACK_RATIO:
588 return val <= DCCPF_ACK_RATIO_MAX;
589 case DCCPF_SEQUENCE_WINDOW:
590 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
591 }
592 return 0; /* feature unknown - so we can't tell */
593}
594
595/* check that SP values are within the ranges defined in RFC 4340 */
596static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
597{
598 switch (feat_num) {
599 case DCCPF_CCID:
600 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
601 /* Type-check Boolean feature values: */
602 case DCCPF_SHORT_SEQNOS:
603 case DCCPF_ECN_INCAPABLE:
604 case DCCPF_SEND_ACK_VECTOR:
605 case DCCPF_SEND_NDP_COUNT:
606 case DCCPF_DATA_CHECKSUM:
607 case DCCPF_SEND_LEV_RATE:
608 return val < 2;
609 case DCCPF_MIN_CSUM_COVER:
610 return val < 16;
611 }
612 return 0; /* feature unknown */
613}
614
615static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
616{
617 if (sp_list == NULL || sp_len < 1)
618 return 0;
619 while (sp_len--)
620 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
621 return 0;
622 return 1;
623}
624
625/**
626 * dccp_feat_insert_opts - Generate FN options from current list state
627 * @skb: next sk_buff to be sent to the peer
628 * @dp: for client during handshake and general negotiation
629 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
630 */
631int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
632 struct sk_buff *skb)
633{
634 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
635 struct dccp_feat_entry *pos, *next;
636 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
637 bool rpt;
638
639 /* put entries into @skb in the order they appear in the list */
640 list_for_each_entry_safe_reverse(pos, next, fn, node) {
641 opt = dccp_feat_genopt(pos);
642 type = dccp_feat_type(pos->feat_num);
643 rpt = false;
644
645 if (pos->empty_confirm) {
646 len = 0;
647 ptr = NULL;
648 } else {
649 if (type == FEAT_SP) {
650 len = pos->val.sp.len;
651 ptr = pos->val.sp.vec;
652 rpt = pos->needs_confirm;
653 } else if (type == FEAT_NN) {
654 len = dccp_feat_valid_nn_length(pos->feat_num);
655 ptr = nn_in_nbo;
656 dccp_encode_value_var(pos->val.nn, ptr, len);
657 } else {
658 DCCP_BUG("unknown feature %u", pos->feat_num);
659 return -1;
660 }
661 }
662 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
663
664 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
665 return -1;
666 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
667 return -1;
668
669 if (skb->sk->sk_state == DCCP_OPEN &&
670 (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) {
671 /*
672 * Confirms don't get retransmitted (6.6.3) once the
673 * connection is in state OPEN
674 */
675 dccp_feat_list_pop(pos);
676 } else {
677 /*
678 * Enter CHANGING after transmitting the Change
679 * option (6.6.2).
680 */
681 if (pos->state == FEAT_INITIALISING)
682 pos->state = FEAT_CHANGING;
683 }
684 }
685 return 0;
686}
687
688/**
689 * __feat_register_nn - Register new NN value on socket
690 * @fn: feature-negotiation list to register with
691 * @feat: an NN feature from %dccp_feature_numbers
692 * @mandatory: use Mandatory option if 1
693 * @nn_val: value to register (restricted to 4 bytes)
694 * Note that NN features are local by definition (RFC 4340, 6.3.2).
695 */
696static int __feat_register_nn(struct list_head *fn, u8 feat,
697 u8 mandatory, u64 nn_val)
698{
699 dccp_feat_val fval = { .nn = nn_val };
700
701 if (dccp_feat_type(feat) != FEAT_NN ||
702 !dccp_feat_is_valid_nn_val(feat, nn_val))
703 return -EINVAL;
704
705 /* Don't bother with default values, they will be activated anyway. */
706 if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
707 return 0;
708
709 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
710}
711
712/**
713 * __feat_register_sp - Register new SP value/list on socket
714 * @fn: feature-negotiation list to register with
715 * @feat: an SP feature from %dccp_feature_numbers
716 * @is_local: whether the local (1) or the remote (0) @feat is meant
717 * @mandatory: use Mandatory option if 1
718 * @sp_val: SP value followed by optional preference list
719 * @sp_len: length of @sp_val in bytes
720 */
721static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
722 u8 mandatory, u8 const *sp_val, u8 sp_len)
723{
724 dccp_feat_val fval;
725
726 if (dccp_feat_type(feat) != FEAT_SP ||
727 !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
728 return -EINVAL;
729
730 /* Avoid negotiating alien CCIDs by only advertising supported ones */
731 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
732 return -EOPNOTSUPP;
733
734 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
735 return -ENOMEM;
736
737 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
738}
739
740/**
741 * dccp_feat_register_sp - Register requests to change SP feature values
742 * @sk: client or listening socket
743 * @feat: one of %dccp_feature_numbers
744 * @is_local: whether the local (1) or remote (0) @feat is meant
745 * @list: array of preferred values, in descending order of preference
746 * @len: length of @list in bytes
747 */
748int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
749 u8 const *list, u8 len)
750{ /* any changes must be registered before establishing the connection */
751 if (sk->sk_state != DCCP_CLOSED)
752 return -EISCONN;
753 if (dccp_feat_type(feat) != FEAT_SP)
754 return -EINVAL;
755 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
756 0, list, len);
757}
758
759/**
760 * dccp_feat_nn_get - Query current/pending value of NN feature
761 * @sk: DCCP socket of an established connection
762 * @feat: NN feature number from %dccp_feature_numbers
763 * For a known NN feature, returns value currently being negotiated, or
764 * current (confirmed) value if no negotiation is going on.
765 */
766u64 dccp_feat_nn_get(struct sock *sk, u8 feat)
767{
768 if (dccp_feat_type(feat) == FEAT_NN) {
769 struct dccp_sock *dp = dccp_sk(sk);
770 struct dccp_feat_entry *entry;
771
772 entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1);
773 if (entry != NULL)
774 return entry->val.nn;
775
776 switch (feat) {
777 case DCCPF_ACK_RATIO:
778 return dp->dccps_l_ack_ratio;
779 case DCCPF_SEQUENCE_WINDOW:
780 return dp->dccps_l_seq_win;
781 }
782 }
783 DCCP_BUG("attempt to look up unsupported feature %u", feat);
784 return 0;
785}
786EXPORT_SYMBOL_GPL(dccp_feat_nn_get);
787
788/**
789 * dccp_feat_signal_nn_change - Update NN values for an established connection
790 * @sk: DCCP socket of an established connection
791 * @feat: NN feature number from %dccp_feature_numbers
792 * @nn_val: the new value to use
793 * This function is used to communicate NN updates out-of-band.
794 */
795int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val)
796{
797 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
798 dccp_feat_val fval = { .nn = nn_val };
799 struct dccp_feat_entry *entry;
800
801 if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN)
802 return 0;
803
804 if (dccp_feat_type(feat) != FEAT_NN ||
805 !dccp_feat_is_valid_nn_val(feat, nn_val))
806 return -EINVAL;
807
808 if (nn_val == dccp_feat_nn_get(sk, feat))
809 return 0; /* already set or negotiation under way */
810
811 entry = dccp_feat_list_lookup(fn, feat, 1);
812 if (entry != NULL) {
813 dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n",
814 (unsigned long long)entry->val.nn,
815 (unsigned long long)nn_val);
816 dccp_feat_list_pop(entry);
817 }
818
819 inet_csk_schedule_ack(sk);
820 return dccp_feat_push_change(fn, feat, 1, 0, &fval);
821}
822EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change);
823
824/*
825 * Tracking features whose value depend on the choice of CCID
826 *
827 * This is designed with an extension in mind so that a list walk could be done
828 * before activating any features. However, the existing framework was found to
829 * work satisfactorily up until now, the automatic verification is left open.
830 * When adding new CCIDs, add a corresponding dependency table here.
831 */
832static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
833{
834 static const struct ccid_dependency ccid2_dependencies[2][2] = {
835 /*
836 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
837 * feature and Send Ack Vector is an RX feature, `is_local'
838 * needs to be reversed.
839 */
840 { /* Dependencies of the receiver-side (remote) CCID2 */
841 {
842 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
843 .is_local = true,
844 .is_mandatory = true,
845 .val = 1
846 },
847 { 0, 0, 0, 0 }
848 },
849 { /* Dependencies of the sender-side (local) CCID2 */
850 {
851 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
852 .is_local = false,
853 .is_mandatory = true,
854 .val = 1
855 },
856 { 0, 0, 0, 0 }
857 }
858 };
859 static const struct ccid_dependency ccid3_dependencies[2][5] = {
860 { /*
861 * Dependencies of the receiver-side CCID3
862 */
863 { /* locally disable Ack Vectors */
864 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
865 .is_local = true,
866 .is_mandatory = false,
867 .val = 0
868 },
869 { /* see below why Send Loss Event Rate is on */
870 .dependent_feat = DCCPF_SEND_LEV_RATE,
871 .is_local = true,
872 .is_mandatory = true,
873 .val = 1
874 },
875 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
876 .dependent_feat = DCCPF_SEND_NDP_COUNT,
877 .is_local = false,
878 .is_mandatory = true,
879 .val = 1
880 },
881 { 0, 0, 0, 0 },
882 },
883 { /*
884 * CCID3 at the TX side: we request that the HC-receiver
885 * will not send Ack Vectors (they will be ignored, so
886 * Mandatory is not set); we enable Send Loss Event Rate
887 * (Mandatory since the implementation does not support
888 * the Loss Intervals option of RFC 4342, 8.6).
889 * The last two options are for peer's information only.
890 */
891 {
892 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
893 .is_local = false,
894 .is_mandatory = false,
895 .val = 0
896 },
897 {
898 .dependent_feat = DCCPF_SEND_LEV_RATE,
899 .is_local = false,
900 .is_mandatory = true,
901 .val = 1
902 },
903 { /* this CCID does not support Ack Ratio */
904 .dependent_feat = DCCPF_ACK_RATIO,
905 .is_local = true,
906 .is_mandatory = false,
907 .val = 0
908 },
909 { /* tell receiver we are sending NDP counts */
910 .dependent_feat = DCCPF_SEND_NDP_COUNT,
911 .is_local = true,
912 .is_mandatory = false,
913 .val = 1
914 },
915 { 0, 0, 0, 0 }
916 }
917 };
918 switch (ccid) {
919 case DCCPC_CCID2:
920 return ccid2_dependencies[is_local];
921 case DCCPC_CCID3:
922 return ccid3_dependencies[is_local];
923 default:
924 return NULL;
925 }
926}
927
928/**
929 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
930 * @fn: feature-negotiation list to update
931 * @id: CCID number to track
932 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
933 * This function needs to be called after registering all other features.
934 */
935static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
936{
937 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
938 int i, rc = (table == NULL);
939
940 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
941 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
942 rc = __feat_register_sp(fn, table[i].dependent_feat,
943 table[i].is_local,
944 table[i].is_mandatory,
945 &table[i].val, 1);
946 else
947 rc = __feat_register_nn(fn, table[i].dependent_feat,
948 table[i].is_mandatory,
949 table[i].val);
950 return rc;
951}
952
953/**
954 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
955 * @dp: client or listening socket (settings will be inherited)
956 * This is called after all registrations (socket initialisation, sysctls, and
957 * sockopt calls), and before sending the first packet containing Change options
958 * (ie. client-Request or server-Response), to ensure internal consistency.
959 */
960int dccp_feat_finalise_settings(struct dccp_sock *dp)
961{
962 struct list_head *fn = &dp->dccps_featneg;
963 struct dccp_feat_entry *entry;
964 int i = 2, ccids[2] = { -1, -1 };
965
966 /*
967 * Propagating CCIDs:
968 * 1) not useful to propagate CCID settings if this host advertises more
969 * than one CCID: the choice of CCID may still change - if this is
970 * the client, or if this is the server and the client sends
971 * singleton CCID values.
972 * 2) since is that propagate_ccid changes the list, we defer changing
973 * the sorted list until after the traversal.
974 */
975 list_for_each_entry(entry, fn, node)
976 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
977 ccids[entry->is_local] = entry->val.sp.vec[0];
978 while (i--)
979 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
980 return -1;
981 dccp_feat_print_fnlist(fn);
982 return 0;
983}
984
985/**
986 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
987 * It is the server which resolves the dependencies once the CCID has been
988 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
989 */
990int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
991{
992 struct list_head *fn = &dreq->dreq_featneg;
993 struct dccp_feat_entry *entry;
994 u8 is_local, ccid;
995
996 for (is_local = 0; is_local <= 1; is_local++) {
997 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
998
999 if (entry != NULL && !entry->empty_confirm)
1000 ccid = entry->val.sp.vec[0];
1001 else
1002 ccid = dccp_feat_default_value(DCCPF_CCID);
1003
1004 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
1005 return -1;
1006 }
1007 return 0;
1008}
1009
1010/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
1011static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
1012{
1013 u8 c, s;
1014
1015 for (s = 0; s < slen; s++)
1016 for (c = 0; c < clen; c++)
1017 if (servlist[s] == clilist[c])
1018 return servlist[s];
1019 return -1;
1020}
1021
1022/**
1023 * dccp_feat_prefer - Move preferred entry to the start of array
1024 * Reorder the @array_len elements in @array so that @preferred_value comes
1025 * first. Returns >0 to indicate that @preferred_value does occur in @array.
1026 */
1027static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
1028{
1029 u8 i, does_occur = 0;
1030
1031 if (array != NULL) {
1032 for (i = 0; i < array_len; i++)
1033 if (array[i] == preferred_value) {
1034 array[i] = array[0];
1035 does_occur++;
1036 }
1037 if (does_occur)
1038 array[0] = preferred_value;
1039 }
1040 return does_occur;
1041}
1042
1043/**
1044 * dccp_feat_reconcile - Reconcile SP preference lists
1045 * @fval: SP list to reconcile into
1046 * @arr: received SP preference list
1047 * @len: length of @arr in bytes
1048 * @is_server: whether this side is the server (and @fv is the server's list)
1049 * @reorder: whether to reorder the list in @fv after reconciling with @arr
1050 * When successful, > 0 is returned and the reconciled list is in @fval.
1051 * A value of 0 means that negotiation failed (no shared entry).
1052 */
1053static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
1054 bool is_server, bool reorder)
1055{
1056 int rc;
1057
1058 if (!fv->sp.vec || !arr) {
1059 DCCP_CRIT("NULL feature value or array");
1060 return 0;
1061 }
1062
1063 if (is_server)
1064 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
1065 else
1066 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
1067
1068 if (!reorder)
1069 return rc;
1070 if (rc < 0)
1071 return 0;
1072
1073 /*
1074 * Reorder list: used for activating features and in dccp_insert_fn_opt.
1075 */
1076 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
1077}
1078
1079/**
1080 * dccp_feat_change_recv - Process incoming ChangeL/R options
1081 * @fn: feature-negotiation list to update
1082 * @is_mandatory: whether the Change was preceded by a Mandatory option
1083 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
1084 * @feat: one of %dccp_feature_numbers
1085 * @val: NN value or SP value/preference list
1086 * @len: length of @val in bytes
1087 * @server: whether this node is the server (1) or the client (0)
1088 */
1089static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1090 u8 feat, u8 *val, u8 len, const bool server)
1091{
1092 u8 defval, type = dccp_feat_type(feat);
1093 const bool local = (opt == DCCPO_CHANGE_R);
1094 struct dccp_feat_entry *entry;
1095 dccp_feat_val fval;
1096
1097 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
1098 goto unknown_feature_or_value;
1099
1100 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1101
1102 /*
1103 * Negotiation of NN features: Change R is invalid, so there is no
1104 * simultaneous negotiation; hence we do not look up in the list.
1105 */
1106 if (type == FEAT_NN) {
1107 if (local || len > sizeof(fval.nn))
1108 goto unknown_feature_or_value;
1109
1110 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1111 fval.nn = dccp_decode_value_var(val, len);
1112 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1113 goto unknown_feature_or_value;
1114
1115 return dccp_feat_push_confirm(fn, feat, local, &fval);
1116 }
1117
1118 /*
1119 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
1120 */
1121 entry = dccp_feat_list_lookup(fn, feat, local);
1122 if (entry == NULL) {
1123 /*
1124 * No particular preferences have been registered. We deal with
1125 * this situation by assuming that all valid values are equally
1126 * acceptable, and apply the following checks:
1127 * - if the peer's list is a singleton, we accept a valid value;
1128 * - if we are the server, we first try to see if the peer (the
1129 * client) advertises the default value. If yes, we use it,
1130 * otherwise we accept the preferred value;
1131 * - else if we are the client, we use the first list element.
1132 */
1133 if (dccp_feat_clone_sp_val(&fval, val, 1))
1134 return DCCP_RESET_CODE_TOO_BUSY;
1135
1136 if (len > 1 && server) {
1137 defval = dccp_feat_default_value(feat);
1138 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1139 fval.sp.vec[0] = defval;
1140 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1141 kfree(fval.sp.vec);
1142 goto unknown_feature_or_value;
1143 }
1144
1145 /* Treat unsupported CCIDs like invalid values */
1146 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1147 kfree(fval.sp.vec);
1148 goto not_valid_or_not_known;
1149 }
1150
1151 return dccp_feat_push_confirm(fn, feat, local, &fval);
1152
1153 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
1154 return 0;
1155 }
1156
1157 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1158 entry->empty_confirm = false;
1159 } else if (is_mandatory) {
1160 return DCCP_RESET_CODE_MANDATORY_ERROR;
1161 } else if (entry->state == FEAT_INITIALISING) {
1162 /*
1163 * Failed simultaneous negotiation (server only): try to `save'
1164 * the connection by checking whether entry contains the default
1165 * value for @feat. If yes, send an empty Confirm to signal that
1166 * the received Change was not understood - which implies using
1167 * the default value.
1168 * If this also fails, we use Reset as the last resort.
1169 */
1170 WARN_ON(!server);
1171 defval = dccp_feat_default_value(feat);
1172 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1173 return DCCP_RESET_CODE_OPTION_ERROR;
1174 entry->empty_confirm = true;
1175 }
1176 entry->needs_confirm = true;
1177 entry->needs_mandatory = false;
1178 entry->state = FEAT_STABLE;
1179 return 0;
1180
1181unknown_feature_or_value:
1182 if (!is_mandatory)
1183 return dccp_push_empty_confirm(fn, feat, local);
1184
1185not_valid_or_not_known:
1186 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1187 : DCCP_RESET_CODE_OPTION_ERROR;
1188}
1189
1190/**
1191 * dccp_feat_confirm_recv - Process received Confirm options
1192 * @fn: feature-negotiation list to update
1193 * @is_mandatory: whether @opt was preceded by a Mandatory option
1194 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
1195 * @feat: one of %dccp_feature_numbers
1196 * @val: NN value or SP value/preference list
1197 * @len: length of @val in bytes
1198 * @server: whether this node is server (1) or client (0)
1199 */
1200static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1201 u8 feat, u8 *val, u8 len, const bool server)
1202{
1203 u8 *plist, plen, type = dccp_feat_type(feat);
1204 const bool local = (opt == DCCPO_CONFIRM_R);
1205 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1206
1207 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1208
1209 if (entry == NULL) { /* nothing queued: ignore or handle error */
1210 if (is_mandatory && type == FEAT_UNKNOWN)
1211 return DCCP_RESET_CODE_MANDATORY_ERROR;
1212
1213 if (!local && type == FEAT_NN) /* 6.3.2 */
1214 goto confirmation_failed;
1215 return 0;
1216 }
1217
1218 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1219 return 0;
1220
1221 if (len == 0) {
1222 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1223 goto confirmation_failed;
1224 /*
1225 * Empty Confirm during connection setup: this means reverting
1226 * to the `old' value, which in this case is the default. Since
1227 * we handle default values automatically when no other values
1228 * have been set, we revert to the old value by removing this
1229 * entry from the list.
1230 */
1231 dccp_feat_list_pop(entry);
1232 return 0;
1233 }
1234
1235 if (type == FEAT_NN) {
1236 if (len > sizeof(entry->val.nn))
1237 goto confirmation_failed;
1238
1239 if (entry->val.nn == dccp_decode_value_var(val, len))
1240 goto confirmation_succeeded;
1241
1242 DCCP_WARN("Bogus Confirm for non-existing value\n");
1243 goto confirmation_failed;
1244 }
1245
1246 /*
1247 * Parsing SP Confirms: the first element of @val is the preferred
1248 * SP value which the peer confirms, the remainder depends on @len.
1249 * Note that only the confirmed value need to be a valid SP value.
1250 */
1251 if (!dccp_feat_is_valid_sp_val(feat, *val))
1252 goto confirmation_failed;
1253
1254 if (len == 1) { /* peer didn't supply a preference list */
1255 plist = val;
1256 plen = len;
1257 } else { /* preferred value + preference list */
1258 plist = val + 1;
1259 plen = len - 1;
1260 }
1261
1262 /* Check whether the peer got the reconciliation right (6.6.8) */
1263 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1264 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1265 return DCCP_RESET_CODE_OPTION_ERROR;
1266 }
1267 entry->val.sp.vec[0] = *val;
1268
1269confirmation_succeeded:
1270 entry->state = FEAT_STABLE;
1271 return 0;
1272
1273confirmation_failed:
1274 DCCP_WARN("Confirmation failed\n");
1275 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1276 : DCCP_RESET_CODE_OPTION_ERROR;
1277}
1278
1279/**
1280 * dccp_feat_handle_nn_established - Fast-path reception of NN options
1281 * @sk: socket of an established DCCP connection
1282 * @mandatory: whether @opt was preceded by a Mandatory option
1283 * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
1284 * @feat: NN number, one of %dccp_feature_numbers
1285 * @val: NN value
1286 * @len: length of @val in bytes
1287 * This function combines the functionality of change_recv/confirm_recv, with
1288 * the following differences (reset codes are the same):
1289 * - cleanup after receiving the Confirm;
1290 * - values are directly activated after successful parsing;
1291 * - deliberately restricted to NN features.
1292 * The restriction to NN features is essential since SP features can have non-
1293 * predictable outcomes (depending on the remote configuration), and are inter-
1294 * dependent (CCIDs for instance cause further dependencies).
1295 */
1296static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
1297 u8 feat, u8 *val, u8 len)
1298{
1299 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1300 const bool local = (opt == DCCPO_CONFIRM_R);
1301 struct dccp_feat_entry *entry;
1302 u8 type = dccp_feat_type(feat);
1303 dccp_feat_val fval;
1304
1305 dccp_feat_print_opt(opt, feat, val, len, mandatory);
1306
1307 /* Ignore non-mandatory unknown and non-NN features */
1308 if (type == FEAT_UNKNOWN) {
1309 if (local && !mandatory)
1310 return 0;
1311 goto fast_path_unknown;
1312 } else if (type != FEAT_NN) {
1313 return 0;
1314 }
1315
1316 /*
1317 * We don't accept empty Confirms, since in fast-path feature
1318 * negotiation the values are enabled immediately after sending
1319 * the Change option.
1320 * Empty Changes on the other hand are invalid (RFC 4340, 6.1).
1321 */
1322 if (len == 0 || len > sizeof(fval.nn))
1323 goto fast_path_unknown;
1324
1325 if (opt == DCCPO_CHANGE_L) {
1326 fval.nn = dccp_decode_value_var(val, len);
1327 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1328 goto fast_path_unknown;
1329
1330 if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
1331 dccp_feat_activate(sk, feat, local, &fval))
1332 return DCCP_RESET_CODE_TOO_BUSY;
1333
1334 /* set the `Ack Pending' flag to piggyback a Confirm */
1335 inet_csk_schedule_ack(sk);
1336
1337 } else if (opt == DCCPO_CONFIRM_R) {
1338 entry = dccp_feat_list_lookup(fn, feat, local);
1339 if (entry == NULL || entry->state != FEAT_CHANGING)
1340 return 0;
1341
1342 fval.nn = dccp_decode_value_var(val, len);
1343 /*
1344 * Just ignore a value that doesn't match our current value.
1345 * If the option changes twice within two RTTs, then at least
1346 * one CONFIRM will be received for the old value after a
1347 * new CHANGE was sent.
1348 */
1349 if (fval.nn != entry->val.nn)
1350 return 0;
1351
1352 /* Only activate after receiving the Confirm option (6.6.1). */
1353 dccp_feat_activate(sk, feat, local, &fval);
1354
1355 /* It has been confirmed - so remove the entry */
1356 dccp_feat_list_pop(entry);
1357
1358 } else {
1359 DCCP_WARN("Received illegal option %u\n", opt);
1360 goto fast_path_failed;
1361 }
1362 return 0;
1363
1364fast_path_unknown:
1365 if (!mandatory)
1366 return dccp_push_empty_confirm(fn, feat, local);
1367
1368fast_path_failed:
1369 return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1370 : DCCP_RESET_CODE_OPTION_ERROR;
1371}
1372
1373/**
1374 * dccp_feat_parse_options - Process Feature-Negotiation Options
1375 * @sk: for general use and used by the client during connection setup
1376 * @dreq: used by the server during connection setup
1377 * @mandatory: whether @opt was preceded by a Mandatory option
1378 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1379 * @feat: one of %dccp_feature_numbers
1380 * @val: value contents of @opt
1381 * @len: length of @val in bytes
1382 * Returns 0 on success, a Reset code for ending the connection otherwise.
1383 */
1384int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1385 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1386{
1387 struct dccp_sock *dp = dccp_sk(sk);
1388 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1389 bool server = false;
1390
1391 switch (sk->sk_state) {
1392 /*
1393 * Negotiation during connection setup
1394 */
1395 case DCCP_LISTEN:
1396 server = true; /* fall through */
1397 case DCCP_REQUESTING:
1398 switch (opt) {
1399 case DCCPO_CHANGE_L:
1400 case DCCPO_CHANGE_R:
1401 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1402 val, len, server);
1403 case DCCPO_CONFIRM_R:
1404 case DCCPO_CONFIRM_L:
1405 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1406 val, len, server);
1407 }
1408 break;
1409 /*
1410 * Support for exchanging NN options on an established connection.
1411 */
1412 case DCCP_OPEN:
1413 case DCCP_PARTOPEN:
1414 return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
1415 val, len);
1416 }
1417 return 0; /* ignore FN options in all other states */
1418}
1419
1420/**
1421 * dccp_feat_init - Seed feature negotiation with host-specific defaults
1422 * This initialises global defaults, depending on the value of the sysctls.
1423 * These can later be overridden by registering changes via setsockopt calls.
1424 * The last link in the chain is finalise_settings, to make sure that between
1425 * here and the start of actual feature negotiation no inconsistencies enter.
1426 *
1427 * All features not appearing below use either defaults or are otherwise
1428 * later adjusted through dccp_feat_finalise_settings().
1429 */
1430int dccp_feat_init(struct sock *sk)
1431{
1432 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1433 u8 on = 1, off = 0;
1434 int rc;
1435 struct {
1436 u8 *val;
1437 u8 len;
1438 } tx, rx;
1439
1440 /* Non-negotiable (NN) features */
1441 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
1442 sysctl_dccp_sequence_window);
1443 if (rc)
1444 return rc;
1445
1446 /* Server-priority (SP) features */
1447
1448 /* Advertise that short seqnos are not supported (7.6.1) */
1449 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
1450 if (rc)
1451 return rc;
1452
1453 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
1454 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
1455 if (rc)
1456 return rc;
1457
1458 /*
1459 * We advertise the available list of CCIDs and reorder according to
1460 * preferences, to avoid failure resulting from negotiating different
1461 * singleton values (which always leads to failure).
1462 * These settings can still (later) be overridden via sockopts.
1463 */
1464 if (ccid_get_builtin_ccids(&tx.val, &tx.len) ||
1465 ccid_get_builtin_ccids(&rx.val, &rx.len))
1466 return -ENOBUFS;
1467
1468 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
1469 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
1470 goto free_ccid_lists;
1471
1472 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
1473 if (rc)
1474 goto free_ccid_lists;
1475
1476 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
1477
1478free_ccid_lists:
1479 kfree(tx.val);
1480 kfree(rx.val);
1481 return rc;
1482}
1483
1484int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1485{
1486 struct dccp_sock *dp = dccp_sk(sk);
1487 struct dccp_feat_entry *cur, *next;
1488 int idx;
1489 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1490 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1491 };
1492
1493 list_for_each_entry(cur, fn_list, node) {
1494 /*
1495 * An empty Confirm means that either an unknown feature type
1496 * or an invalid value was present. In the first case there is
1497 * nothing to activate, in the other the default value is used.
1498 */
1499 if (cur->empty_confirm)
1500 continue;
1501
1502 idx = dccp_feat_index(cur->feat_num);
1503 if (idx < 0) {
1504 DCCP_BUG("Unknown feature %u", cur->feat_num);
1505 goto activation_failed;
1506 }
1507 if (cur->state != FEAT_STABLE) {
1508 DCCP_CRIT("Negotiation of %s %s failed in state %s",
1509 cur->is_local ? "local" : "remote",
1510 dccp_feat_fname(cur->feat_num),
1511 dccp_feat_sname[cur->state]);
1512 goto activation_failed;
1513 }
1514 fvals[idx][cur->is_local] = &cur->val;
1515 }
1516
1517 /*
1518 * Activate in decreasing order of index, so that the CCIDs are always
1519 * activated as the last feature. This avoids the case where a CCID
1520 * relies on the initialisation of one or more features that it depends
1521 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1522 */
1523 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1524 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1525 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1526 DCCP_CRIT("Could not activate %d", idx);
1527 goto activation_failed;
1528 }
1529
1530 /* Clean up Change options which have been confirmed already */
1531 list_for_each_entry_safe(cur, next, fn_list, node)
1532 if (!cur->needs_confirm)
1533 dccp_feat_list_pop(cur);
1534
1535 dccp_pr_debug("Activation OK\n");
1536 return 0;
1537
1538activation_failed:
1539 /*
1540 * We clean up everything that may have been allocated, since
1541 * it is difficult to track at which stage negotiation failed.
1542 * This is ok, since all allocation functions below are robust
1543 * against NULL arguments.
1544 */
1545 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1546 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1547 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1548 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1549 dp->dccps_hc_rx_ackvec = NULL;
1550 return -1;
1551}