Loading...
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/dccp/feat.c
4 *
5 * Feature negotiation for the DCCP protocol (RFC 4340, section 6)
6 *
7 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
8 * Rewrote from scratch, some bits from earlier code by
9 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
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#include <linux/module.h>
21#include <linux/slab.h>
22#include "ccid.h"
23#include "feat.h"
24
25/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
26unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
27int sysctl_dccp_rx_ccid __read_mostly = 2,
28 sysctl_dccp_tx_ccid __read_mostly = 2;
29
30/*
31 * Feature activation handlers.
32 *
33 * These all use an u64 argument, to provide enough room for NN/SP features. At
34 * this stage the negotiated values have been checked to be within their range.
35 */
36static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
37{
38 struct dccp_sock *dp = dccp_sk(sk);
39 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
40
41 if (new_ccid == NULL)
42 return -ENOMEM;
43
44 if (rx) {
45 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
46 dp->dccps_hc_rx_ccid = new_ccid;
47 } else {
48 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
49 dp->dccps_hc_tx_ccid = new_ccid;
50 }
51 return 0;
52}
53
54static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
55{
56 struct dccp_sock *dp = dccp_sk(sk);
57
58 if (rx) {
59 dp->dccps_r_seq_win = seq_win;
60 /* propagate changes to update SWL/SWH */
61 dccp_update_gsr(sk, dp->dccps_gsr);
62 } else {
63 dp->dccps_l_seq_win = seq_win;
64 /* propagate changes to update AWL */
65 dccp_update_gss(sk, dp->dccps_gss);
66 }
67 return 0;
68}
69
70static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
71{
72 if (rx)
73 dccp_sk(sk)->dccps_r_ack_ratio = ratio;
74 else
75 dccp_sk(sk)->dccps_l_ack_ratio = ratio;
76 return 0;
77}
78
79static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
80{
81 struct dccp_sock *dp = dccp_sk(sk);
82
83 if (rx) {
84 if (enable && dp->dccps_hc_rx_ackvec == NULL) {
85 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
86 if (dp->dccps_hc_rx_ackvec == NULL)
87 return -ENOMEM;
88 } else if (!enable) {
89 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
90 dp->dccps_hc_rx_ackvec = NULL;
91 }
92 }
93 return 0;
94}
95
96static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
97{
98 if (!rx)
99 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
100 return 0;
101}
102
103/*
104 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
105 * `rx' holds when the sending peer informs about his partial coverage via a
106 * ChangeR() option. In the other case, we are the sender and the receiver
107 * announces its coverage via ChangeL() options. The policy here is to honour
108 * such communication by enabling the corresponding partial coverage - but only
109 * if it has not been set manually before; the warning here means that all
110 * packets will be dropped.
111 */
112static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
113{
114 struct dccp_sock *dp = dccp_sk(sk);
115
116 if (rx)
117 dp->dccps_pcrlen = cscov;
118 else {
119 if (dp->dccps_pcslen == 0)
120 dp->dccps_pcslen = cscov;
121 else if (cscov > dp->dccps_pcslen)
122 DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
123 dp->dccps_pcslen, (u8)cscov);
124 }
125 return 0;
126}
127
128static const struct {
129 u8 feat_num; /* DCCPF_xxx */
130 enum dccp_feat_type rxtx; /* RX or TX */
131 enum dccp_feat_type reconciliation; /* SP or NN */
132 u8 default_value; /* as in 6.4 */
133 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
134/*
135 * Lookup table for location and type of features (from RFC 4340/4342)
136 * +--------------------------+----+-----+----+----+---------+-----------+
137 * | Feature | Location | Reconc. | Initial | Section |
138 * | | RX | TX | SP | NN | Value | Reference |
139 * +--------------------------+----+-----+----+----+---------+-----------+
140 * | DCCPF_CCID | | X | X | | 2 | 10 |
141 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
142 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
143 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
144 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
145 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
146 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
147 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
148 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
149 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
150 * +--------------------------+----+-----+----+----+---------+-----------+
151 */
152} dccp_feat_table[] = {
153 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
154 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
155 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
156 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
157 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
158 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
159 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
160 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
161 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
162 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
163};
164#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
165
166/**
167 * dccp_feat_index - Hash function to map feature number into array position
168 * @feat_num: feature to hash, one of %dccp_feature_numbers
169 *
170 * Returns consecutive array index or -1 if the feature is not understood.
171 */
172static int dccp_feat_index(u8 feat_num)
173{
174 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
175 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
176 return feat_num - 1;
177
178 /*
179 * Other features: add cases for new feature types here after adding
180 * them to the above table.
181 */
182 switch (feat_num) {
183 case DCCPF_SEND_LEV_RATE:
184 return DCCP_FEAT_SUPPORTED_MAX - 1;
185 }
186 return -1;
187}
188
189static u8 dccp_feat_type(u8 feat_num)
190{
191 int idx = dccp_feat_index(feat_num);
192
193 if (idx < 0)
194 return FEAT_UNKNOWN;
195 return dccp_feat_table[idx].reconciliation;
196}
197
198static int dccp_feat_default_value(u8 feat_num)
199{
200 int idx = dccp_feat_index(feat_num);
201 /*
202 * There are no default values for unknown features, so encountering a
203 * negative index here indicates a serious problem somewhere else.
204 */
205 DCCP_BUG_ON(idx < 0);
206
207 return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
208}
209
210/*
211 * Debugging and verbose-printing section
212 */
213static const char *dccp_feat_fname(const u8 feat)
214{
215 static const char *const feature_names[] = {
216 [DCCPF_RESERVED] = "Reserved",
217 [DCCPF_CCID] = "CCID",
218 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
219 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
220 [DCCPF_ECN_INCAPABLE] = "ECN Incapable",
221 [DCCPF_ACK_RATIO] = "Ack Ratio",
222 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
223 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
224 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
225 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
226 };
227 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
228 return feature_names[DCCPF_RESERVED];
229
230 if (feat == DCCPF_SEND_LEV_RATE)
231 return "Send Loss Event Rate";
232 if (feat >= DCCPF_MIN_CCID_SPECIFIC)
233 return "CCID-specific";
234
235 return feature_names[feat];
236}
237
238static const char *const dccp_feat_sname[] = {
239 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
240};
241
242#ifdef CONFIG_IP_DCCP_DEBUG
243static const char *dccp_feat_oname(const u8 opt)
244{
245 switch (opt) {
246 case DCCPO_CHANGE_L: return "Change_L";
247 case DCCPO_CONFIRM_L: return "Confirm_L";
248 case DCCPO_CHANGE_R: return "Change_R";
249 case DCCPO_CONFIRM_R: return "Confirm_R";
250 }
251 return NULL;
252}
253
254static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val)
255{
256 u8 i, type = dccp_feat_type(feat_num);
257
258 if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL))
259 dccp_pr_debug_cat("(NULL)");
260 else if (type == FEAT_SP)
261 for (i = 0; i < val->sp.len; i++)
262 dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]);
263 else if (type == FEAT_NN)
264 dccp_pr_debug_cat("%llu", (unsigned long long)val->nn);
265 else
266 dccp_pr_debug_cat("unknown type %u", type);
267}
268
269static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len)
270{
271 u8 type = dccp_feat_type(feat_num);
272 dccp_feat_val fval = { .sp.vec = list, .sp.len = len };
273
274 if (type == FEAT_NN)
275 fval.nn = dccp_decode_value_var(list, len);
276 dccp_feat_printval(feat_num, &fval);
277}
278
279static void dccp_feat_print_entry(struct dccp_feat_entry const *entry)
280{
281 dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote",
282 dccp_feat_fname(entry->feat_num));
283 dccp_feat_printval(entry->feat_num, &entry->val);
284 dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state],
285 entry->needs_confirm ? "(Confirm pending)" : "");
286}
287
288#define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \
289 dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\
290 dccp_feat_printvals(feat, val, len); \
291 dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0)
292
293#define dccp_feat_print_fnlist(fn_list) { \
294 const struct dccp_feat_entry *___entry; \
295 \
296 dccp_pr_debug("List Dump:\n"); \
297 list_for_each_entry(___entry, fn_list, node) \
298 dccp_feat_print_entry(___entry); \
299}
300#else /* ! CONFIG_IP_DCCP_DEBUG */
301#define dccp_feat_print_opt(opt, feat, val, len, mandatory)
302#define dccp_feat_print_fnlist(fn_list)
303#endif
304
305static int __dccp_feat_activate(struct sock *sk, const int idx,
306 const bool is_local, dccp_feat_val const *fval)
307{
308 bool rx;
309 u64 val;
310
311 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
312 return -1;
313 if (dccp_feat_table[idx].activation_hdlr == NULL)
314 return 0;
315
316 if (fval == NULL) {
317 val = dccp_feat_table[idx].default_value;
318 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
319 if (fval->sp.vec == NULL) {
320 /*
321 * This can happen when an empty Confirm is sent
322 * for an SP (i.e. known) feature. In this case
323 * we would be using the default anyway.
324 */
325 DCCP_CRIT("Feature #%d undefined: using default", idx);
326 val = dccp_feat_table[idx].default_value;
327 } else {
328 val = fval->sp.vec[0];
329 }
330 } else {
331 val = fval->nn;
332 }
333
334 /* Location is RX if this is a local-RX or remote-TX feature */
335 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
336
337 dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX",
338 dccp_feat_fname(dccp_feat_table[idx].feat_num),
339 fval ? "" : "default ", (unsigned long long)val);
340
341 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
342}
343
344/**
345 * dccp_feat_activate - Activate feature value on socket
346 * @sk: fully connected DCCP socket (after handshake is complete)
347 * @feat_num: feature to activate, one of %dccp_feature_numbers
348 * @local: whether local (1) or remote (0) @feat_num is meant
349 * @fval: the value (SP or NN) to activate, or NULL to use the default value
350 *
351 * For general use this function is preferable over __dccp_feat_activate().
352 */
353static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
354 dccp_feat_val const *fval)
355{
356 return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
357}
358
359/* Test for "Req'd" feature (RFC 4340, 6.4) */
360static inline int dccp_feat_must_be_understood(u8 feat_num)
361{
362 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
363 feat_num == DCCPF_SEQUENCE_WINDOW;
364}
365
366/* copy constructor, fval must not already contain allocated memory */
367static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
368{
369 fval->sp.len = len;
370 if (fval->sp.len > 0) {
371 fval->sp.vec = kmemdup(val, len, gfp_any());
372 if (fval->sp.vec == NULL) {
373 fval->sp.len = 0;
374 return -ENOMEM;
375 }
376 }
377 return 0;
378}
379
380static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
381{
382 if (unlikely(val == NULL))
383 return;
384 if (dccp_feat_type(feat_num) == FEAT_SP)
385 kfree(val->sp.vec);
386 memset(val, 0, sizeof(*val));
387}
388
389static struct dccp_feat_entry *
390 dccp_feat_clone_entry(struct dccp_feat_entry const *original)
391{
392 struct dccp_feat_entry *new;
393 u8 type = dccp_feat_type(original->feat_num);
394
395 if (type == FEAT_UNKNOWN)
396 return NULL;
397
398 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
399 if (new == NULL)
400 return NULL;
401
402 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
403 original->val.sp.vec,
404 original->val.sp.len)) {
405 kfree(new);
406 return NULL;
407 }
408 return new;
409}
410
411static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
412{
413 if (entry != NULL) {
414 dccp_feat_val_destructor(entry->feat_num, &entry->val);
415 kfree(entry);
416 }
417}
418
419/*
420 * List management functions
421 *
422 * Feature negotiation lists rely on and maintain the following invariants:
423 * - each feat_num in the list is known, i.e. we know its type and default value
424 * - each feat_num/is_local combination is unique (old entries are overwritten)
425 * - SP values are always freshly allocated
426 * - list is sorted in increasing order of feature number (faster lookup)
427 */
428static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
429 u8 feat_num, bool is_local)
430{
431 struct dccp_feat_entry *entry;
432
433 list_for_each_entry(entry, fn_list, node) {
434 if (entry->feat_num == feat_num && entry->is_local == is_local)
435 return entry;
436 else if (entry->feat_num > feat_num)
437 break;
438 }
439 return NULL;
440}
441
442/**
443 * dccp_feat_entry_new - Central list update routine (called by all others)
444 * @head: list to add to
445 * @feat: feature number
446 * @local: whether the local (1) or remote feature with number @feat is meant
447 *
448 * This is the only constructor and serves to ensure the above invariants.
449 */
450static struct dccp_feat_entry *
451 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
452{
453 struct dccp_feat_entry *entry;
454
455 list_for_each_entry(entry, head, node)
456 if (entry->feat_num == feat && entry->is_local == local) {
457 dccp_feat_val_destructor(entry->feat_num, &entry->val);
458 return entry;
459 } else if (entry->feat_num > feat) {
460 head = &entry->node;
461 break;
462 }
463
464 entry = kmalloc(sizeof(*entry), gfp_any());
465 if (entry != NULL) {
466 entry->feat_num = feat;
467 entry->is_local = local;
468 list_add_tail(&entry->node, head);
469 }
470 return entry;
471}
472
473/**
474 * dccp_feat_push_change - Add/overwrite a Change option in the list
475 * @fn_list: feature-negotiation list to update
476 * @feat: one of %dccp_feature_numbers
477 * @local: whether local (1) or remote (0) @feat_num is meant
478 * @mandatory: whether to use Mandatory feature negotiation options
479 * @fval: pointer to NN/SP value to be inserted (will be copied)
480 */
481static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
482 u8 mandatory, dccp_feat_val *fval)
483{
484 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
485
486 if (new == NULL)
487 return -ENOMEM;
488
489 new->feat_num = feat;
490 new->is_local = local;
491 new->state = FEAT_INITIALISING;
492 new->needs_confirm = false;
493 new->empty_confirm = false;
494 new->val = *fval;
495 new->needs_mandatory = mandatory;
496
497 return 0;
498}
499
500/**
501 * dccp_feat_push_confirm - Add a Confirm entry to the FN list
502 * @fn_list: feature-negotiation list to add to
503 * @feat: one of %dccp_feature_numbers
504 * @local: whether local (1) or remote (0) @feat_num is being confirmed
505 * @fval: pointer to NN/SP value to be inserted or NULL
506 *
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 * @feat_num: feature to return length of, one of %dccp_feature_numbers
573 *
574 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
575 * incoming options are accepted as long as their values are valid.
576 */
577static u8 dccp_feat_valid_nn_length(u8 feat_num)
578{
579 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
580 return 2;
581 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
582 return 6;
583 return 0;
584}
585
586static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
587{
588 switch (feat_num) {
589 case DCCPF_ACK_RATIO:
590 return val <= DCCPF_ACK_RATIO_MAX;
591 case DCCPF_SEQUENCE_WINDOW:
592 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
593 }
594 return 0; /* feature unknown - so we can't tell */
595}
596
597/* check that SP values are within the ranges defined in RFC 4340 */
598static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
599{
600 switch (feat_num) {
601 case DCCPF_CCID:
602 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
603 /* Type-check Boolean feature values: */
604 case DCCPF_SHORT_SEQNOS:
605 case DCCPF_ECN_INCAPABLE:
606 case DCCPF_SEND_ACK_VECTOR:
607 case DCCPF_SEND_NDP_COUNT:
608 case DCCPF_DATA_CHECKSUM:
609 case DCCPF_SEND_LEV_RATE:
610 return val < 2;
611 case DCCPF_MIN_CSUM_COVER:
612 return val < 16;
613 }
614 return 0; /* feature unknown */
615}
616
617static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
618{
619 if (sp_list == NULL || sp_len < 1)
620 return 0;
621 while (sp_len--)
622 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
623 return 0;
624 return 1;
625}
626
627/**
628 * dccp_feat_insert_opts - Generate FN options from current list state
629 * @skb: next sk_buff to be sent to the peer
630 * @dp: for client during handshake and general negotiation
631 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
632 */
633int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
634 struct sk_buff *skb)
635{
636 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
637 struct dccp_feat_entry *pos, *next;
638 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
639 bool rpt;
640
641 /* put entries into @skb in the order they appear in the list */
642 list_for_each_entry_safe_reverse(pos, next, fn, node) {
643 opt = dccp_feat_genopt(pos);
644 type = dccp_feat_type(pos->feat_num);
645 rpt = false;
646
647 if (pos->empty_confirm) {
648 len = 0;
649 ptr = NULL;
650 } else {
651 if (type == FEAT_SP) {
652 len = pos->val.sp.len;
653 ptr = pos->val.sp.vec;
654 rpt = pos->needs_confirm;
655 } else if (type == FEAT_NN) {
656 len = dccp_feat_valid_nn_length(pos->feat_num);
657 ptr = nn_in_nbo;
658 dccp_encode_value_var(pos->val.nn, ptr, len);
659 } else {
660 DCCP_BUG("unknown feature %u", pos->feat_num);
661 return -1;
662 }
663 }
664 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
665
666 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
667 return -1;
668 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
669 return -1;
670
671 if (skb->sk->sk_state == DCCP_OPEN &&
672 (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) {
673 /*
674 * Confirms don't get retransmitted (6.6.3) once the
675 * connection is in state OPEN
676 */
677 dccp_feat_list_pop(pos);
678 } else {
679 /*
680 * Enter CHANGING after transmitting the Change
681 * option (6.6.2).
682 */
683 if (pos->state == FEAT_INITIALISING)
684 pos->state = FEAT_CHANGING;
685 }
686 }
687 return 0;
688}
689
690/**
691 * __feat_register_nn - Register new NN value on socket
692 * @fn: feature-negotiation list to register with
693 * @feat: an NN feature from %dccp_feature_numbers
694 * @mandatory: use Mandatory option if 1
695 * @nn_val: value to register (restricted to 4 bytes)
696 *
697 * Note that NN features are local by definition (RFC 4340, 6.3.2).
698 */
699static int __feat_register_nn(struct list_head *fn, u8 feat,
700 u8 mandatory, u64 nn_val)
701{
702 dccp_feat_val fval = { .nn = nn_val };
703
704 if (dccp_feat_type(feat) != FEAT_NN ||
705 !dccp_feat_is_valid_nn_val(feat, nn_val))
706 return -EINVAL;
707
708 /* Don't bother with default values, they will be activated anyway. */
709 if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
710 return 0;
711
712 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
713}
714
715/**
716 * __feat_register_sp - Register new SP value/list on socket
717 * @fn: feature-negotiation list to register with
718 * @feat: an SP feature from %dccp_feature_numbers
719 * @is_local: whether the local (1) or the remote (0) @feat is meant
720 * @mandatory: use Mandatory option if 1
721 * @sp_val: SP value followed by optional preference list
722 * @sp_len: length of @sp_val in bytes
723 */
724static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
725 u8 mandatory, u8 const *sp_val, u8 sp_len)
726{
727 dccp_feat_val fval;
728
729 if (dccp_feat_type(feat) != FEAT_SP ||
730 !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
731 return -EINVAL;
732
733 /* Avoid negotiating alien CCIDs by only advertising supported ones */
734 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
735 return -EOPNOTSUPP;
736
737 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
738 return -ENOMEM;
739
740 if (dccp_feat_push_change(fn, feat, is_local, mandatory, &fval)) {
741 kfree(fval.sp.vec);
742 return -ENOMEM;
743 }
744
745 return 0;
746}
747
748/**
749 * dccp_feat_register_sp - Register requests to change SP feature values
750 * @sk: client or listening socket
751 * @feat: one of %dccp_feature_numbers
752 * @is_local: whether the local (1) or remote (0) @feat is meant
753 * @list: array of preferred values, in descending order of preference
754 * @len: length of @list in bytes
755 */
756int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
757 u8 const *list, u8 len)
758{ /* any changes must be registered before establishing the connection */
759 if (sk->sk_state != DCCP_CLOSED)
760 return -EISCONN;
761 if (dccp_feat_type(feat) != FEAT_SP)
762 return -EINVAL;
763 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
764 0, list, len);
765}
766
767/**
768 * dccp_feat_nn_get - Query current/pending value of NN feature
769 * @sk: DCCP socket of an established connection
770 * @feat: NN feature number from %dccp_feature_numbers
771 *
772 * For a known NN feature, returns value currently being negotiated, or
773 * current (confirmed) value if no negotiation is going on.
774 */
775u64 dccp_feat_nn_get(struct sock *sk, u8 feat)
776{
777 if (dccp_feat_type(feat) == FEAT_NN) {
778 struct dccp_sock *dp = dccp_sk(sk);
779 struct dccp_feat_entry *entry;
780
781 entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1);
782 if (entry != NULL)
783 return entry->val.nn;
784
785 switch (feat) {
786 case DCCPF_ACK_RATIO:
787 return dp->dccps_l_ack_ratio;
788 case DCCPF_SEQUENCE_WINDOW:
789 return dp->dccps_l_seq_win;
790 }
791 }
792 DCCP_BUG("attempt to look up unsupported feature %u", feat);
793 return 0;
794}
795EXPORT_SYMBOL_GPL(dccp_feat_nn_get);
796
797/**
798 * dccp_feat_signal_nn_change - Update NN values for an established connection
799 * @sk: DCCP socket of an established connection
800 * @feat: NN feature number from %dccp_feature_numbers
801 * @nn_val: the new value to use
802 *
803 * This function is used to communicate NN updates out-of-band.
804 */
805int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val)
806{
807 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
808 dccp_feat_val fval = { .nn = nn_val };
809 struct dccp_feat_entry *entry;
810
811 if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN)
812 return 0;
813
814 if (dccp_feat_type(feat) != FEAT_NN ||
815 !dccp_feat_is_valid_nn_val(feat, nn_val))
816 return -EINVAL;
817
818 if (nn_val == dccp_feat_nn_get(sk, feat))
819 return 0; /* already set or negotiation under way */
820
821 entry = dccp_feat_list_lookup(fn, feat, 1);
822 if (entry != NULL) {
823 dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n",
824 (unsigned long long)entry->val.nn,
825 (unsigned long long)nn_val);
826 dccp_feat_list_pop(entry);
827 }
828
829 inet_csk_schedule_ack(sk);
830 return dccp_feat_push_change(fn, feat, 1, 0, &fval);
831}
832EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change);
833
834/*
835 * Tracking features whose value depend on the choice of CCID
836 *
837 * This is designed with an extension in mind so that a list walk could be done
838 * before activating any features. However, the existing framework was found to
839 * work satisfactorily up until now, the automatic verification is left open.
840 * When adding new CCIDs, add a corresponding dependency table here.
841 */
842static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
843{
844 static const struct ccid_dependency ccid2_dependencies[2][2] = {
845 /*
846 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
847 * feature and Send Ack Vector is an RX feature, `is_local'
848 * needs to be reversed.
849 */
850 { /* Dependencies of the receiver-side (remote) CCID2 */
851 {
852 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
853 .is_local = true,
854 .is_mandatory = true,
855 .val = 1
856 },
857 { 0, 0, 0, 0 }
858 },
859 { /* Dependencies of the sender-side (local) CCID2 */
860 {
861 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
862 .is_local = false,
863 .is_mandatory = true,
864 .val = 1
865 },
866 { 0, 0, 0, 0 }
867 }
868 };
869 static const struct ccid_dependency ccid3_dependencies[2][5] = {
870 { /*
871 * Dependencies of the receiver-side CCID3
872 */
873 { /* locally disable Ack Vectors */
874 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
875 .is_local = true,
876 .is_mandatory = false,
877 .val = 0
878 },
879 { /* see below why Send Loss Event Rate is on */
880 .dependent_feat = DCCPF_SEND_LEV_RATE,
881 .is_local = true,
882 .is_mandatory = true,
883 .val = 1
884 },
885 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
886 .dependent_feat = DCCPF_SEND_NDP_COUNT,
887 .is_local = false,
888 .is_mandatory = true,
889 .val = 1
890 },
891 { 0, 0, 0, 0 },
892 },
893 { /*
894 * CCID3 at the TX side: we request that the HC-receiver
895 * will not send Ack Vectors (they will be ignored, so
896 * Mandatory is not set); we enable Send Loss Event Rate
897 * (Mandatory since the implementation does not support
898 * the Loss Intervals option of RFC 4342, 8.6).
899 * The last two options are for peer's information only.
900 */
901 {
902 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
903 .is_local = false,
904 .is_mandatory = false,
905 .val = 0
906 },
907 {
908 .dependent_feat = DCCPF_SEND_LEV_RATE,
909 .is_local = false,
910 .is_mandatory = true,
911 .val = 1
912 },
913 { /* this CCID does not support Ack Ratio */
914 .dependent_feat = DCCPF_ACK_RATIO,
915 .is_local = true,
916 .is_mandatory = false,
917 .val = 0
918 },
919 { /* tell receiver we are sending NDP counts */
920 .dependent_feat = DCCPF_SEND_NDP_COUNT,
921 .is_local = true,
922 .is_mandatory = false,
923 .val = 1
924 },
925 { 0, 0, 0, 0 }
926 }
927 };
928 switch (ccid) {
929 case DCCPC_CCID2:
930 return ccid2_dependencies[is_local];
931 case DCCPC_CCID3:
932 return ccid3_dependencies[is_local];
933 default:
934 return NULL;
935 }
936}
937
938/**
939 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
940 * @fn: feature-negotiation list to update
941 * @id: CCID number to track
942 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
943 *
944 * This function needs to be called after registering all other features.
945 */
946static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
947{
948 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
949 int i, rc = (table == NULL);
950
951 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
952 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
953 rc = __feat_register_sp(fn, table[i].dependent_feat,
954 table[i].is_local,
955 table[i].is_mandatory,
956 &table[i].val, 1);
957 else
958 rc = __feat_register_nn(fn, table[i].dependent_feat,
959 table[i].is_mandatory,
960 table[i].val);
961 return rc;
962}
963
964/**
965 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
966 * @dp: client or listening socket (settings will be inherited)
967 *
968 * This is called after all registrations (socket initialisation, sysctls, and
969 * sockopt calls), and before sending the first packet containing Change options
970 * (ie. client-Request or server-Response), to ensure internal consistency.
971 */
972int dccp_feat_finalise_settings(struct dccp_sock *dp)
973{
974 struct list_head *fn = &dp->dccps_featneg;
975 struct dccp_feat_entry *entry;
976 int i = 2, ccids[2] = { -1, -1 };
977
978 /*
979 * Propagating CCIDs:
980 * 1) not useful to propagate CCID settings if this host advertises more
981 * than one CCID: the choice of CCID may still change - if this is
982 * the client, or if this is the server and the client sends
983 * singleton CCID values.
984 * 2) since is that propagate_ccid changes the list, we defer changing
985 * the sorted list until after the traversal.
986 */
987 list_for_each_entry(entry, fn, node)
988 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
989 ccids[entry->is_local] = entry->val.sp.vec[0];
990 while (i--)
991 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
992 return -1;
993 dccp_feat_print_fnlist(fn);
994 return 0;
995}
996
997/**
998 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
999 * @dreq: server socket to resolve
1000 *
1001 * It is the server which resolves the dependencies once the CCID has been
1002 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
1003 */
1004int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
1005{
1006 struct list_head *fn = &dreq->dreq_featneg;
1007 struct dccp_feat_entry *entry;
1008 u8 is_local, ccid;
1009
1010 for (is_local = 0; is_local <= 1; is_local++) {
1011 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
1012
1013 if (entry != NULL && !entry->empty_confirm)
1014 ccid = entry->val.sp.vec[0];
1015 else
1016 ccid = dccp_feat_default_value(DCCPF_CCID);
1017
1018 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
1019 return -1;
1020 }
1021 return 0;
1022}
1023
1024/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
1025static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
1026{
1027 u8 c, s;
1028
1029 for (s = 0; s < slen; s++)
1030 for (c = 0; c < clen; c++)
1031 if (servlist[s] == clilist[c])
1032 return servlist[s];
1033 return -1;
1034}
1035
1036/**
1037 * dccp_feat_prefer - Move preferred entry to the start of array
1038 * @preferred_value: entry to move to start of array
1039 * @array: array of preferred entries
1040 * @array_len: size of the array
1041 *
1042 * Reorder the @array_len elements in @array so that @preferred_value comes
1043 * first. Returns >0 to indicate that @preferred_value does occur in @array.
1044 */
1045static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
1046{
1047 u8 i, does_occur = 0;
1048
1049 if (array != NULL) {
1050 for (i = 0; i < array_len; i++)
1051 if (array[i] == preferred_value) {
1052 array[i] = array[0];
1053 does_occur++;
1054 }
1055 if (does_occur)
1056 array[0] = preferred_value;
1057 }
1058 return does_occur;
1059}
1060
1061/**
1062 * dccp_feat_reconcile - Reconcile SP preference lists
1063 * @fv: SP list to reconcile into
1064 * @arr: received SP preference list
1065 * @len: length of @arr in bytes
1066 * @is_server: whether this side is the server (and @fv is the server's list)
1067 * @reorder: whether to reorder the list in @fv after reconciling with @arr
1068 * When successful, > 0 is returned and the reconciled list is in @fval.
1069 * A value of 0 means that negotiation failed (no shared entry).
1070 */
1071static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
1072 bool is_server, bool reorder)
1073{
1074 int rc;
1075
1076 if (!fv->sp.vec || !arr) {
1077 DCCP_CRIT("NULL feature value or array");
1078 return 0;
1079 }
1080
1081 if (is_server)
1082 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
1083 else
1084 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
1085
1086 if (!reorder)
1087 return rc;
1088 if (rc < 0)
1089 return 0;
1090
1091 /*
1092 * Reorder list: used for activating features and in dccp_insert_fn_opt.
1093 */
1094 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
1095}
1096
1097/**
1098 * dccp_feat_change_recv - Process incoming ChangeL/R options
1099 * @fn: feature-negotiation list to update
1100 * @is_mandatory: whether the Change was preceded by a Mandatory option
1101 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
1102 * @feat: one of %dccp_feature_numbers
1103 * @val: NN value or SP value/preference list
1104 * @len: length of @val in bytes
1105 * @server: whether this node is the server (1) or the client (0)
1106 */
1107static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1108 u8 feat, u8 *val, u8 len, const bool server)
1109{
1110 u8 defval, type = dccp_feat_type(feat);
1111 const bool local = (opt == DCCPO_CHANGE_R);
1112 struct dccp_feat_entry *entry;
1113 dccp_feat_val fval;
1114
1115 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
1116 goto unknown_feature_or_value;
1117
1118 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1119
1120 /*
1121 * Negotiation of NN features: Change R is invalid, so there is no
1122 * simultaneous negotiation; hence we do not look up in the list.
1123 */
1124 if (type == FEAT_NN) {
1125 if (local || len > sizeof(fval.nn))
1126 goto unknown_feature_or_value;
1127
1128 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1129 fval.nn = dccp_decode_value_var(val, len);
1130 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1131 goto unknown_feature_or_value;
1132
1133 return dccp_feat_push_confirm(fn, feat, local, &fval);
1134 }
1135
1136 /*
1137 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
1138 */
1139 entry = dccp_feat_list_lookup(fn, feat, local);
1140 if (entry == NULL) {
1141 /*
1142 * No particular preferences have been registered. We deal with
1143 * this situation by assuming that all valid values are equally
1144 * acceptable, and apply the following checks:
1145 * - if the peer's list is a singleton, we accept a valid value;
1146 * - if we are the server, we first try to see if the peer (the
1147 * client) advertises the default value. If yes, we use it,
1148 * otherwise we accept the preferred value;
1149 * - else if we are the client, we use the first list element.
1150 */
1151 if (dccp_feat_clone_sp_val(&fval, val, 1))
1152 return DCCP_RESET_CODE_TOO_BUSY;
1153
1154 if (len > 1 && server) {
1155 defval = dccp_feat_default_value(feat);
1156 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1157 fval.sp.vec[0] = defval;
1158 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1159 kfree(fval.sp.vec);
1160 goto unknown_feature_or_value;
1161 }
1162
1163 /* Treat unsupported CCIDs like invalid values */
1164 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1165 kfree(fval.sp.vec);
1166 goto not_valid_or_not_known;
1167 }
1168
1169 if (dccp_feat_push_confirm(fn, feat, local, &fval)) {
1170 kfree(fval.sp.vec);
1171 return DCCP_RESET_CODE_TOO_BUSY;
1172 }
1173
1174 return 0;
1175 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
1176 return 0;
1177 }
1178
1179 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1180 entry->empty_confirm = false;
1181 } else if (is_mandatory) {
1182 return DCCP_RESET_CODE_MANDATORY_ERROR;
1183 } else if (entry->state == FEAT_INITIALISING) {
1184 /*
1185 * Failed simultaneous negotiation (server only): try to `save'
1186 * the connection by checking whether entry contains the default
1187 * value for @feat. If yes, send an empty Confirm to signal that
1188 * the received Change was not understood - which implies using
1189 * the default value.
1190 * If this also fails, we use Reset as the last resort.
1191 */
1192 WARN_ON(!server);
1193 defval = dccp_feat_default_value(feat);
1194 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1195 return DCCP_RESET_CODE_OPTION_ERROR;
1196 entry->empty_confirm = true;
1197 }
1198 entry->needs_confirm = true;
1199 entry->needs_mandatory = false;
1200 entry->state = FEAT_STABLE;
1201 return 0;
1202
1203unknown_feature_or_value:
1204 if (!is_mandatory)
1205 return dccp_push_empty_confirm(fn, feat, local);
1206
1207not_valid_or_not_known:
1208 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1209 : DCCP_RESET_CODE_OPTION_ERROR;
1210}
1211
1212/**
1213 * dccp_feat_confirm_recv - Process received Confirm options
1214 * @fn: feature-negotiation list to update
1215 * @is_mandatory: whether @opt was preceded by a Mandatory option
1216 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
1217 * @feat: one of %dccp_feature_numbers
1218 * @val: NN value or SP value/preference list
1219 * @len: length of @val in bytes
1220 * @server: whether this node is server (1) or client (0)
1221 */
1222static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1223 u8 feat, u8 *val, u8 len, const bool server)
1224{
1225 u8 *plist, plen, type = dccp_feat_type(feat);
1226 const bool local = (opt == DCCPO_CONFIRM_R);
1227 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1228
1229 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1230
1231 if (entry == NULL) { /* nothing queued: ignore or handle error */
1232 if (is_mandatory && type == FEAT_UNKNOWN)
1233 return DCCP_RESET_CODE_MANDATORY_ERROR;
1234
1235 if (!local && type == FEAT_NN) /* 6.3.2 */
1236 goto confirmation_failed;
1237 return 0;
1238 }
1239
1240 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1241 return 0;
1242
1243 if (len == 0) {
1244 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1245 goto confirmation_failed;
1246 /*
1247 * Empty Confirm during connection setup: this means reverting
1248 * to the `old' value, which in this case is the default. Since
1249 * we handle default values automatically when no other values
1250 * have been set, we revert to the old value by removing this
1251 * entry from the list.
1252 */
1253 dccp_feat_list_pop(entry);
1254 return 0;
1255 }
1256
1257 if (type == FEAT_NN) {
1258 if (len > sizeof(entry->val.nn))
1259 goto confirmation_failed;
1260
1261 if (entry->val.nn == dccp_decode_value_var(val, len))
1262 goto confirmation_succeeded;
1263
1264 DCCP_WARN("Bogus Confirm for non-existing value\n");
1265 goto confirmation_failed;
1266 }
1267
1268 /*
1269 * Parsing SP Confirms: the first element of @val is the preferred
1270 * SP value which the peer confirms, the remainder depends on @len.
1271 * Note that only the confirmed value need to be a valid SP value.
1272 */
1273 if (!dccp_feat_is_valid_sp_val(feat, *val))
1274 goto confirmation_failed;
1275
1276 if (len == 1) { /* peer didn't supply a preference list */
1277 plist = val;
1278 plen = len;
1279 } else { /* preferred value + preference list */
1280 plist = val + 1;
1281 plen = len - 1;
1282 }
1283
1284 /* Check whether the peer got the reconciliation right (6.6.8) */
1285 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1286 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1287 return DCCP_RESET_CODE_OPTION_ERROR;
1288 }
1289 entry->val.sp.vec[0] = *val;
1290
1291confirmation_succeeded:
1292 entry->state = FEAT_STABLE;
1293 return 0;
1294
1295confirmation_failed:
1296 DCCP_WARN("Confirmation failed\n");
1297 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1298 : DCCP_RESET_CODE_OPTION_ERROR;
1299}
1300
1301/**
1302 * dccp_feat_handle_nn_established - Fast-path reception of NN options
1303 * @sk: socket of an established DCCP connection
1304 * @mandatory: whether @opt was preceded by a Mandatory option
1305 * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
1306 * @feat: NN number, one of %dccp_feature_numbers
1307 * @val: NN value
1308 * @len: length of @val in bytes
1309 *
1310 * This function combines the functionality of change_recv/confirm_recv, with
1311 * the following differences (reset codes are the same):
1312 * - cleanup after receiving the Confirm;
1313 * - values are directly activated after successful parsing;
1314 * - deliberately restricted to NN features.
1315 * The restriction to NN features is essential since SP features can have non-
1316 * predictable outcomes (depending on the remote configuration), and are inter-
1317 * dependent (CCIDs for instance cause further dependencies).
1318 */
1319static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
1320 u8 feat, u8 *val, u8 len)
1321{
1322 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1323 const bool local = (opt == DCCPO_CONFIRM_R);
1324 struct dccp_feat_entry *entry;
1325 u8 type = dccp_feat_type(feat);
1326 dccp_feat_val fval;
1327
1328 dccp_feat_print_opt(opt, feat, val, len, mandatory);
1329
1330 /* Ignore non-mandatory unknown and non-NN features */
1331 if (type == FEAT_UNKNOWN) {
1332 if (local && !mandatory)
1333 return 0;
1334 goto fast_path_unknown;
1335 } else if (type != FEAT_NN) {
1336 return 0;
1337 }
1338
1339 /*
1340 * We don't accept empty Confirms, since in fast-path feature
1341 * negotiation the values are enabled immediately after sending
1342 * the Change option.
1343 * Empty Changes on the other hand are invalid (RFC 4340, 6.1).
1344 */
1345 if (len == 0 || len > sizeof(fval.nn))
1346 goto fast_path_unknown;
1347
1348 if (opt == DCCPO_CHANGE_L) {
1349 fval.nn = dccp_decode_value_var(val, len);
1350 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1351 goto fast_path_unknown;
1352
1353 if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
1354 dccp_feat_activate(sk, feat, local, &fval))
1355 return DCCP_RESET_CODE_TOO_BUSY;
1356
1357 /* set the `Ack Pending' flag to piggyback a Confirm */
1358 inet_csk_schedule_ack(sk);
1359
1360 } else if (opt == DCCPO_CONFIRM_R) {
1361 entry = dccp_feat_list_lookup(fn, feat, local);
1362 if (entry == NULL || entry->state != FEAT_CHANGING)
1363 return 0;
1364
1365 fval.nn = dccp_decode_value_var(val, len);
1366 /*
1367 * Just ignore a value that doesn't match our current value.
1368 * If the option changes twice within two RTTs, then at least
1369 * one CONFIRM will be received for the old value after a
1370 * new CHANGE was sent.
1371 */
1372 if (fval.nn != entry->val.nn)
1373 return 0;
1374
1375 /* Only activate after receiving the Confirm option (6.6.1). */
1376 dccp_feat_activate(sk, feat, local, &fval);
1377
1378 /* It has been confirmed - so remove the entry */
1379 dccp_feat_list_pop(entry);
1380
1381 } else {
1382 DCCP_WARN("Received illegal option %u\n", opt);
1383 goto fast_path_failed;
1384 }
1385 return 0;
1386
1387fast_path_unknown:
1388 if (!mandatory)
1389 return dccp_push_empty_confirm(fn, feat, local);
1390
1391fast_path_failed:
1392 return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1393 : DCCP_RESET_CODE_OPTION_ERROR;
1394}
1395
1396/**
1397 * dccp_feat_parse_options - Process Feature-Negotiation Options
1398 * @sk: for general use and used by the client during connection setup
1399 * @dreq: used by the server during connection setup
1400 * @mandatory: whether @opt was preceded by a Mandatory option
1401 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1402 * @feat: one of %dccp_feature_numbers
1403 * @val: value contents of @opt
1404 * @len: length of @val in bytes
1405 *
1406 * Returns 0 on success, a Reset code for ending the connection otherwise.
1407 */
1408int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1409 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1410{
1411 struct dccp_sock *dp = dccp_sk(sk);
1412 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1413 bool server = false;
1414
1415 switch (sk->sk_state) {
1416 /*
1417 * Negotiation during connection setup
1418 */
1419 case DCCP_LISTEN:
1420 server = true;
1421 fallthrough;
1422 case DCCP_REQUESTING:
1423 switch (opt) {
1424 case DCCPO_CHANGE_L:
1425 case DCCPO_CHANGE_R:
1426 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1427 val, len, server);
1428 case DCCPO_CONFIRM_R:
1429 case DCCPO_CONFIRM_L:
1430 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1431 val, len, server);
1432 }
1433 break;
1434 /*
1435 * Support for exchanging NN options on an established connection.
1436 */
1437 case DCCP_OPEN:
1438 case DCCP_PARTOPEN:
1439 return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
1440 val, len);
1441 }
1442 return 0; /* ignore FN options in all other states */
1443}
1444
1445/**
1446 * dccp_feat_init - Seed feature negotiation with host-specific defaults
1447 * @sk: Socket to initialize.
1448 *
1449 * This initialises global defaults, depending on the value of the sysctls.
1450 * These can later be overridden by registering changes via setsockopt calls.
1451 * The last link in the chain is finalise_settings, to make sure that between
1452 * here and the start of actual feature negotiation no inconsistencies enter.
1453 *
1454 * All features not appearing below use either defaults or are otherwise
1455 * later adjusted through dccp_feat_finalise_settings().
1456 */
1457int dccp_feat_init(struct sock *sk)
1458{
1459 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1460 u8 on = 1, off = 0;
1461 int rc;
1462 struct {
1463 u8 *val;
1464 u8 len;
1465 } tx, rx;
1466
1467 /* Non-negotiable (NN) features */
1468 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
1469 sysctl_dccp_sequence_window);
1470 if (rc)
1471 return rc;
1472
1473 /* Server-priority (SP) features */
1474
1475 /* Advertise that short seqnos are not supported (7.6.1) */
1476 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
1477 if (rc)
1478 return rc;
1479
1480 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
1481 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
1482 if (rc)
1483 return rc;
1484
1485 /*
1486 * We advertise the available list of CCIDs and reorder according to
1487 * preferences, to avoid failure resulting from negotiating different
1488 * singleton values (which always leads to failure).
1489 * These settings can still (later) be overridden via sockopts.
1490 */
1491 if (ccid_get_builtin_ccids(&tx.val, &tx.len))
1492 return -ENOBUFS;
1493 if (ccid_get_builtin_ccids(&rx.val, &rx.len)) {
1494 kfree(tx.val);
1495 return -ENOBUFS;
1496 }
1497
1498 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
1499 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
1500 goto free_ccid_lists;
1501
1502 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
1503 if (rc)
1504 goto free_ccid_lists;
1505
1506 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
1507
1508free_ccid_lists:
1509 kfree(tx.val);
1510 kfree(rx.val);
1511 return rc;
1512}
1513
1514int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1515{
1516 struct dccp_sock *dp = dccp_sk(sk);
1517 struct dccp_feat_entry *cur, *next;
1518 int idx;
1519 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1520 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1521 };
1522
1523 list_for_each_entry(cur, fn_list, node) {
1524 /*
1525 * An empty Confirm means that either an unknown feature type
1526 * or an invalid value was present. In the first case there is
1527 * nothing to activate, in the other the default value is used.
1528 */
1529 if (cur->empty_confirm)
1530 continue;
1531
1532 idx = dccp_feat_index(cur->feat_num);
1533 if (idx < 0) {
1534 DCCP_BUG("Unknown feature %u", cur->feat_num);
1535 goto activation_failed;
1536 }
1537 if (cur->state != FEAT_STABLE) {
1538 DCCP_CRIT("Negotiation of %s %s failed in state %s",
1539 cur->is_local ? "local" : "remote",
1540 dccp_feat_fname(cur->feat_num),
1541 dccp_feat_sname[cur->state]);
1542 goto activation_failed;
1543 }
1544 fvals[idx][cur->is_local] = &cur->val;
1545 }
1546
1547 /*
1548 * Activate in decreasing order of index, so that the CCIDs are always
1549 * activated as the last feature. This avoids the case where a CCID
1550 * relies on the initialisation of one or more features that it depends
1551 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1552 */
1553 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1554 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1555 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1556 DCCP_CRIT("Could not activate %d", idx);
1557 goto activation_failed;
1558 }
1559
1560 /* Clean up Change options which have been confirmed already */
1561 list_for_each_entry_safe(cur, next, fn_list, node)
1562 if (!cur->needs_confirm)
1563 dccp_feat_list_pop(cur);
1564
1565 dccp_pr_debug("Activation OK\n");
1566 return 0;
1567
1568activation_failed:
1569 /*
1570 * We clean up everything that may have been allocated, since
1571 * it is difficult to track at which stage negotiation failed.
1572 * This is ok, since all allocation functions below are robust
1573 * against NULL arguments.
1574 */
1575 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1576 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1577 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1578 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1579 dp->dccps_hc_rx_ackvec = NULL;
1580 return -1;
1581}
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}