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Andrea Bittauafe00252006-03-20 17:43:56 -08001/*
2 * net/dccp/feat.c
3 *
Gerrit Renker63b8e282008-12-08 01:17:32 -08004 * 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 *
Andrea Bittauafe00252006-03-20 17:43:56 -080010 *
Gerrit Renker5cdae192007-12-13 12:41:46 -020011 * ASSUMPTIONS
12 * -----------
Gerrit Renkerf74e91b2008-11-12 00:42:58 -080013 * o Feature negotiation is coordinated with connection setup (as in TCP), wild
14 * changes of parameters of an established connection are not supported.
Gerrit Renker5cdae192007-12-13 12:41:46 -020015 * 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.
Andrea Bittauafe00252006-03-20 17:43:56 -080023 */
Andrea Bittauafe00252006-03-20 17:43:56 -080024#include <linux/module.h>
Andrea Bittau6ffd30f2006-03-20 19:22:37 -080025#include "ccid.h"
Andrea Bittauafe00252006-03-20 17:43:56 -080026#include "feat.h"
27
Gerrit Renker883ca832009-01-16 23:36:32 +000028/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
29unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
30int sysctl_dccp_rx_ccid __read_mostly = 2,
31 sysctl_dccp_tx_ccid __read_mostly = 2;
32
Gerrit Renker422d9cd2008-12-01 23:34:01 -080033/*
34 * Feature activation handlers.
35 *
36 * These all use an u64 argument, to provide enough room for NN/SP features. At
37 * this stage the negotiated values have been checked to be within their range.
38 */
39static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
40{
41 struct dccp_sock *dp = dccp_sk(sk);
Gerrit Renkere5fd56c2009-01-04 21:43:23 -080042 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
Gerrit Renker422d9cd2008-12-01 23:34:01 -080043
44 if (new_ccid == NULL)
45 return -ENOMEM;
46
47 if (rx) {
48 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
49 dp->dccps_hc_rx_ccid = new_ccid;
50 } else {
51 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
52 dp->dccps_hc_tx_ccid = new_ccid;
53 }
54 return 0;
55}
56
57static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
58{
Gerrit Renker792b4872009-01-16 23:36:31 +000059 struct dccp_sock *dp = dccp_sk(sk);
60
61 if (rx) {
62 dp->dccps_r_seq_win = seq_win;
63 /* propagate changes to update SWL/SWH */
64 dccp_update_gsr(sk, dp->dccps_gsr);
65 } else {
66 dp->dccps_l_seq_win = seq_win;
67 /* propagate changes to update AWL */
68 dccp_update_gss(sk, dp->dccps_gss);
69 }
Gerrit Renker422d9cd2008-12-01 23:34:01 -080070 return 0;
71}
72
73static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
74{
75 if (rx)
76 dccp_sk(sk)->dccps_r_ack_ratio = ratio;
77 else
78 dccp_sk(sk)->dccps_l_ack_ratio = ratio;
79 return 0;
80}
81
82static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
83{
84 struct dccp_sock *dp = dccp_sk(sk);
85
86 if (rx) {
87 if (enable && dp->dccps_hc_rx_ackvec == NULL) {
88 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
89 if (dp->dccps_hc_rx_ackvec == NULL)
90 return -ENOMEM;
91 } else if (!enable) {
92 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
93 dp->dccps_hc_rx_ackvec = NULL;
94 }
95 }
96 return 0;
97}
98
99static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
100{
101 if (!rx)
Gerrit Renker4098dce2008-12-08 01:18:37 -0800102 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800103 return 0;
104}
105
106/*
107 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
108 * `rx' holds when the sending peer informs about his partial coverage via a
109 * ChangeR() option. In the other case, we are the sender and the receiver
110 * announces its coverage via ChangeL() options. The policy here is to honour
111 * such communication by enabling the corresponding partial coverage - but only
112 * if it has not been set manually before; the warning here means that all
113 * packets will be dropped.
114 */
115static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
116{
117 struct dccp_sock *dp = dccp_sk(sk);
118
119 if (rx)
120 dp->dccps_pcrlen = cscov;
121 else {
122 if (dp->dccps_pcslen == 0)
123 dp->dccps_pcslen = cscov;
124 else if (cscov > dp->dccps_pcslen)
125 DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
126 dp->dccps_pcslen, (u8)cscov);
127 }
128 return 0;
129}
130
Gerrit Renker7d43d1a02008-11-04 23:43:47 -0800131static const struct {
132 u8 feat_num; /* DCCPF_xxx */
133 enum dccp_feat_type rxtx; /* RX or TX */
134 enum dccp_feat_type reconciliation; /* SP or NN */
135 u8 default_value; /* as in 6.4 */
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800136 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
Gerrit Renker7d43d1a02008-11-04 23:43:47 -0800137/*
138 * Lookup table for location and type of features (from RFC 4340/4342)
139 * +--------------------------+----+-----+----+----+---------+-----------+
140 * | Feature | Location | Reconc. | Initial | Section |
141 * | | RX | TX | SP | NN | Value | Reference |
142 * +--------------------------+----+-----+----+----+---------+-----------+
143 * | DCCPF_CCID | | X | X | | 2 | 10 |
144 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
145 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
146 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
147 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
148 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
149 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
150 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
151 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
152 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
153 * +--------------------------+----+-----+----+----+---------+-----------+
154 */
155} dccp_feat_table[] = {
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800156 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
157 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
158 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
159 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
160 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
161 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
162 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
163 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
164 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
165 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
Gerrit Renker7d43d1a02008-11-04 23:43:47 -0800166};
167#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
168
Gerrit Renker61e64732008-11-04 23:54:04 -0800169/**
170 * dccp_feat_index - Hash function to map feature number into array position
171 * Returns consecutive array index or -1 if the feature is not understood.
172 */
173static int dccp_feat_index(u8 feat_num)
174{
175 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
176 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
177 return feat_num - 1;
178
179 /*
180 * Other features: add cases for new feature types here after adding
181 * them to the above table.
182 */
183 switch (feat_num) {
184 case DCCPF_SEND_LEV_RATE:
185 return DCCP_FEAT_SUPPORTED_MAX - 1;
186 }
187 return -1;
188}
189
190static u8 dccp_feat_type(u8 feat_num)
191{
192 int idx = dccp_feat_index(feat_num);
193
194 if (idx < 0)
195 return FEAT_UNKNOWN;
196 return dccp_feat_table[idx].reconciliation;
197}
198
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800199static int dccp_feat_default_value(u8 feat_num)
200{
201 int idx = dccp_feat_index(feat_num);
202 /*
203 * There are no default values for unknown features, so encountering a
204 * negative index here indicates a serious problem somewhere else.
205 */
206 DCCP_BUG_ON(idx < 0);
207
208 return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
209}
210
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000211/*
212 * Debugging and verbose-printing section
213 */
214static const char *dccp_feat_fname(const u8 feat)
215{
216 static const char *feature_names[] = {
217 [DCCPF_RESERVED] = "Reserved",
218 [DCCPF_CCID] = "CCID",
219 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
220 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
221 [DCCPF_ECN_INCAPABLE] = "ECN Incapable",
222 [DCCPF_ACK_RATIO] = "Ack Ratio",
223 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
224 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
225 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
226 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
227 };
228 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
229 return feature_names[DCCPF_RESERVED];
230
231 if (feat == DCCPF_SEND_LEV_RATE)
232 return "Send Loss Event Rate";
233 if (feat >= DCCPF_MIN_CCID_SPECIFIC)
234 return "CCID-specific";
235
236 return feature_names[feat];
237}
238
239static const char *dccp_feat_sname[] = { "DEFAULT", "INITIALISING", "CHANGING",
240 "UNSTABLE", "STABLE" };
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
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800305static 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
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000337 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
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800341 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
342}
343
Gerrit Renkerb1ad0042008-12-01 23:33:18 -0800344/* Test for "Req'd" feature (RFC 4340, 6.4) */
345static inline int dccp_feat_must_be_understood(u8 feat_num)
346{
347 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
348 feat_num == DCCPF_SEQUENCE_WINDOW;
349}
350
Gerrit Renkerac757732008-11-04 23:55:49 -0800351/* copy constructor, fval must not already contain allocated memory */
352static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
353{
354 fval->sp.len = len;
355 if (fval->sp.len > 0) {
356 fval->sp.vec = kmemdup(val, len, gfp_any());
357 if (fval->sp.vec == NULL) {
358 fval->sp.len = 0;
359 return -ENOBUFS;
360 }
361 }
362 return 0;
363}
364
Gerrit Renker61e64732008-11-04 23:54:04 -0800365static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
366{
367 if (unlikely(val == NULL))
368 return;
369 if (dccp_feat_type(feat_num) == FEAT_SP)
370 kfree(val->sp.vec);
371 memset(val, 0, sizeof(*val));
372}
373
Gerrit Renkerac757732008-11-04 23:55:49 -0800374static struct dccp_feat_entry *
375 dccp_feat_clone_entry(struct dccp_feat_entry const *original)
376{
377 struct dccp_feat_entry *new;
378 u8 type = dccp_feat_type(original->feat_num);
379
380 if (type == FEAT_UNKNOWN)
381 return NULL;
382
383 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
384 if (new == NULL)
385 return NULL;
386
387 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
388 original->val.sp.vec,
389 original->val.sp.len)) {
390 kfree(new);
391 return NULL;
392 }
393 return new;
394}
395
Gerrit Renker61e64732008-11-04 23:54:04 -0800396static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
397{
398 if (entry != NULL) {
399 dccp_feat_val_destructor(entry->feat_num, &entry->val);
400 kfree(entry);
401 }
402}
403
404/*
405 * List management functions
406 *
407 * Feature negotiation lists rely on and maintain the following invariants:
408 * - each feat_num in the list is known, i.e. we know its type and default value
409 * - each feat_num/is_local combination is unique (old entries are overwritten)
410 * - SP values are always freshly allocated
411 * - list is sorted in increasing order of feature number (faster lookup)
412 */
Gerrit Renker0c116832008-11-16 22:49:52 -0800413static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
414 u8 feat_num, bool is_local)
415{
416 struct dccp_feat_entry *entry;
417
Gerrit Renker3d3e35a2008-11-20 01:03:08 -0800418 list_for_each_entry(entry, fn_list, node) {
Gerrit Renker0c116832008-11-16 22:49:52 -0800419 if (entry->feat_num == feat_num && entry->is_local == is_local)
420 return entry;
421 else if (entry->feat_num > feat_num)
422 break;
Gerrit Renker3d3e35a2008-11-20 01:03:08 -0800423 }
Gerrit Renker0c116832008-11-16 22:49:52 -0800424 return NULL;
425}
Gerrit Renker61e64732008-11-04 23:54:04 -0800426
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800427/**
428 * dccp_feat_entry_new - Central list update routine (called by all others)
429 * @head: list to add to
430 * @feat: feature number
431 * @local: whether the local (1) or remote feature with number @feat is meant
432 * This is the only constructor and serves to ensure the above invariants.
433 */
434static struct dccp_feat_entry *
435 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
436{
437 struct dccp_feat_entry *entry;
438
439 list_for_each_entry(entry, head, node)
440 if (entry->feat_num == feat && entry->is_local == local) {
441 dccp_feat_val_destructor(entry->feat_num, &entry->val);
442 return entry;
443 } else if (entry->feat_num > feat) {
444 head = &entry->node;
445 break;
446 }
447
448 entry = kmalloc(sizeof(*entry), gfp_any());
449 if (entry != NULL) {
450 entry->feat_num = feat;
451 entry->is_local = local;
452 list_add_tail(&entry->node, head);
453 }
454 return entry;
455}
456
457/**
458 * dccp_feat_push_change - Add/overwrite a Change option in the list
459 * @fn_list: feature-negotiation list to update
460 * @feat: one of %dccp_feature_numbers
461 * @local: whether local (1) or remote (0) @feat_num is meant
462 * @needs_mandatory: whether to use Mandatory feature negotiation options
463 * @fval: pointer to NN/SP value to be inserted (will be copied)
464 */
465static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
466 u8 mandatory, dccp_feat_val *fval)
467{
468 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
469
470 if (new == NULL)
471 return -ENOMEM;
472
473 new->feat_num = feat;
474 new->is_local = local;
475 new->state = FEAT_INITIALISING;
476 new->needs_confirm = 0;
477 new->empty_confirm = 0;
478 new->val = *fval;
479 new->needs_mandatory = mandatory;
480
481 return 0;
482}
483
Gerrit Renkere77b8362008-12-01 23:32:35 -0800484/**
485 * dccp_feat_push_confirm - Add a Confirm entry to the FN list
486 * @fn_list: feature-negotiation list to add to
487 * @feat: one of %dccp_feature_numbers
488 * @local: whether local (1) or remote (0) @feat_num is being confirmed
489 * @fval: pointer to NN/SP value to be inserted or NULL
490 * Returns 0 on success, a Reset code for further processing otherwise.
491 */
492static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
493 dccp_feat_val *fval)
494{
495 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
496
497 if (new == NULL)
498 return DCCP_RESET_CODE_TOO_BUSY;
499
500 new->feat_num = feat;
501 new->is_local = local;
502 new->state = FEAT_STABLE; /* transition in 6.6.2 */
503 new->needs_confirm = 1;
504 new->empty_confirm = (fval == NULL);
505 new->val.nn = 0; /* zeroes the whole structure */
506 if (!new->empty_confirm)
507 new->val = *fval;
508 new->needs_mandatory = 0;
509
510 return 0;
511}
512
513static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
514{
515 return dccp_feat_push_confirm(fn_list, feat, local, NULL);
516}
517
Gerrit Renker61e64732008-11-04 23:54:04 -0800518static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
519{
520 list_del(&entry->node);
521 dccp_feat_entry_destructor(entry);
522}
523
524void dccp_feat_list_purge(struct list_head *fn_list)
525{
526 struct dccp_feat_entry *entry, *next;
527
528 list_for_each_entry_safe(entry, next, fn_list, node)
529 dccp_feat_entry_destructor(entry);
530 INIT_LIST_HEAD(fn_list);
531}
532EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
533
Gerrit Renkerac757732008-11-04 23:55:49 -0800534/* generate @to as full clone of @from - @to must not contain any nodes */
535int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
536{
537 struct dccp_feat_entry *entry, *new;
538
539 INIT_LIST_HEAD(to);
540 list_for_each_entry(entry, from, node) {
541 new = dccp_feat_clone_entry(entry);
542 if (new == NULL)
543 goto cloning_failed;
544 list_add_tail(&new->node, to);
545 }
546 return 0;
547
548cloning_failed:
549 dccp_feat_list_purge(to);
550 return -ENOMEM;
551}
552
Gerrit Renker0971d172008-12-01 23:27:31 -0800553/**
554 * dccp_feat_valid_nn_length - Enforce length constraints on NN options
555 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
556 * incoming options are accepted as long as their values are valid.
557 */
558static u8 dccp_feat_valid_nn_length(u8 feat_num)
559{
560 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
561 return 2;
562 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
563 return 6;
564 return 0;
565}
566
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800567static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
568{
569 switch (feat_num) {
570 case DCCPF_ACK_RATIO:
571 return val <= DCCPF_ACK_RATIO_MAX;
572 case DCCPF_SEQUENCE_WINDOW:
573 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
574 }
575 return 0; /* feature unknown - so we can't tell */
576}
577
578/* check that SP values are within the ranges defined in RFC 4340 */
579static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
580{
581 switch (feat_num) {
582 case DCCPF_CCID:
583 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
584 /* Type-check Boolean feature values: */
585 case DCCPF_SHORT_SEQNOS:
586 case DCCPF_ECN_INCAPABLE:
587 case DCCPF_SEND_ACK_VECTOR:
588 case DCCPF_SEND_NDP_COUNT:
589 case DCCPF_DATA_CHECKSUM:
590 case DCCPF_SEND_LEV_RATE:
591 return val < 2;
592 case DCCPF_MIN_CSUM_COVER:
593 return val < 16;
594 }
595 return 0; /* feature unknown */
596}
597
598static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
599{
600 if (sp_list == NULL || sp_len < 1)
601 return 0;
602 while (sp_len--)
603 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
604 return 0;
605 return 1;
606}
607
608/**
Gerrit Renker0971d172008-12-01 23:27:31 -0800609 * dccp_feat_insert_opts - Generate FN options from current list state
610 * @skb: next sk_buff to be sent to the peer
611 * @dp: for client during handshake and general negotiation
612 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
613 */
614int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
615 struct sk_buff *skb)
616{
617 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
618 struct dccp_feat_entry *pos, *next;
619 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
620 bool rpt;
621
622 /* put entries into @skb in the order they appear in the list */
623 list_for_each_entry_safe_reverse(pos, next, fn, node) {
624 opt = dccp_feat_genopt(pos);
625 type = dccp_feat_type(pos->feat_num);
626 rpt = false;
627
628 if (pos->empty_confirm) {
629 len = 0;
630 ptr = NULL;
631 } else {
632 if (type == FEAT_SP) {
633 len = pos->val.sp.len;
634 ptr = pos->val.sp.vec;
635 rpt = pos->needs_confirm;
636 } else if (type == FEAT_NN) {
637 len = dccp_feat_valid_nn_length(pos->feat_num);
638 ptr = nn_in_nbo;
639 dccp_encode_value_var(pos->val.nn, ptr, len);
640 } else {
641 DCCP_BUG("unknown feature %u", pos->feat_num);
642 return -1;
643 }
644 }
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000645 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
Gerrit Renker0971d172008-12-01 23:27:31 -0800646
647 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
648 return -1;
649 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
650 return -1;
651 /*
652 * Enter CHANGING after transmitting the Change option (6.6.2).
653 */
654 if (pos->state == FEAT_INITIALISING)
655 pos->state = FEAT_CHANGING;
656 }
657 return 0;
658}
659
660/**
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800661 * __feat_register_nn - Register new NN value on socket
662 * @fn: feature-negotiation list to register with
663 * @feat: an NN feature from %dccp_feature_numbers
664 * @mandatory: use Mandatory option if 1
665 * @nn_val: value to register (restricted to 4 bytes)
666 * Note that NN features are local by definition (RFC 4340, 6.3.2).
667 */
668static int __feat_register_nn(struct list_head *fn, u8 feat,
669 u8 mandatory, u64 nn_val)
670{
671 dccp_feat_val fval = { .nn = nn_val };
672
673 if (dccp_feat_type(feat) != FEAT_NN ||
674 !dccp_feat_is_valid_nn_val(feat, nn_val))
675 return -EINVAL;
676
677 /* Don't bother with default values, they will be activated anyway. */
678 if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
679 return 0;
680
681 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
682}
683
684/**
685 * __feat_register_sp - Register new SP value/list on socket
686 * @fn: feature-negotiation list to register with
687 * @feat: an SP feature from %dccp_feature_numbers
688 * @is_local: whether the local (1) or the remote (0) @feat is meant
689 * @mandatory: use Mandatory option if 1
690 * @sp_val: SP value followed by optional preference list
691 * @sp_len: length of @sp_val in bytes
692 */
693static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
694 u8 mandatory, u8 const *sp_val, u8 sp_len)
695{
696 dccp_feat_val fval;
697
698 if (dccp_feat_type(feat) != FEAT_SP ||
699 !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
700 return -EINVAL;
701
Gerrit Renkerd90ebcb2008-11-12 00:47:26 -0800702 /* Avoid negotiating alien CCIDs by only advertising supported ones */
703 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
704 return -EOPNOTSUPP;
705
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800706 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
707 return -ENOMEM;
708
709 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
710}
711
Gerrit Renker49aebc62008-11-16 22:51:23 -0800712/**
713 * dccp_feat_register_sp - Register requests to change SP feature values
714 * @sk: client or listening socket
715 * @feat: one of %dccp_feature_numbers
716 * @is_local: whether the local (1) or remote (0) @feat is meant
717 * @list: array of preferred values, in descending order of preference
718 * @len: length of @list in bytes
719 */
720int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
721 u8 const *list, u8 len)
722{ /* any changes must be registered before establishing the connection */
723 if (sk->sk_state != DCCP_CLOSED)
724 return -EISCONN;
725 if (dccp_feat_type(feat) != FEAT_SP)
Chris Wright19443172008-05-05 13:50:24 -0700726 return -EINVAL;
Gerrit Renker49aebc62008-11-16 22:51:23 -0800727 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
728 0, list, len);
Andrea Bittauafe00252006-03-20 17:43:56 -0800729}
730
Gerrit Renker49aebc62008-11-16 22:51:23 -0800731/* Analogous to dccp_feat_register_sp(), but for non-negotiable values */
732int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val)
733{
734 /* any changes must be registered before establishing the connection */
735 if (sk->sk_state != DCCP_CLOSED)
736 return -EISCONN;
737 if (dccp_feat_type(feat) != FEAT_NN)
738 return -EINVAL;
739 return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val);
740}
Andrea Bittauafe00252006-03-20 17:43:56 -0800741
Gerrit Renker9eca0a42008-11-12 00:48:44 -0800742/*
743 * Tracking features whose value depend on the choice of CCID
744 *
745 * This is designed with an extension in mind so that a list walk could be done
746 * before activating any features. However, the existing framework was found to
747 * work satisfactorily up until now, the automatic verification is left open.
748 * When adding new CCIDs, add a corresponding dependency table here.
749 */
750static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
751{
752 static const struct ccid_dependency ccid2_dependencies[2][2] = {
753 /*
754 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
755 * feature and Send Ack Vector is an RX feature, `is_local'
756 * needs to be reversed.
757 */
758 { /* Dependencies of the receiver-side (remote) CCID2 */
759 {
760 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
761 .is_local = true,
762 .is_mandatory = true,
763 .val = 1
764 },
765 { 0, 0, 0, 0 }
766 },
767 { /* Dependencies of the sender-side (local) CCID2 */
768 {
769 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
770 .is_local = false,
771 .is_mandatory = true,
772 .val = 1
773 },
774 { 0, 0, 0, 0 }
775 }
776 };
777 static const struct ccid_dependency ccid3_dependencies[2][5] = {
778 { /*
779 * Dependencies of the receiver-side CCID3
780 */
781 { /* locally disable Ack Vectors */
782 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
783 .is_local = true,
784 .is_mandatory = false,
785 .val = 0
786 },
787 { /* see below why Send Loss Event Rate is on */
788 .dependent_feat = DCCPF_SEND_LEV_RATE,
789 .is_local = true,
790 .is_mandatory = true,
791 .val = 1
792 },
793 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
794 .dependent_feat = DCCPF_SEND_NDP_COUNT,
795 .is_local = false,
796 .is_mandatory = true,
797 .val = 1
798 },
799 { 0, 0, 0, 0 },
800 },
801 { /*
802 * CCID3 at the TX side: we request that the HC-receiver
803 * will not send Ack Vectors (they will be ignored, so
804 * Mandatory is not set); we enable Send Loss Event Rate
805 * (Mandatory since the implementation does not support
806 * the Loss Intervals option of RFC 4342, 8.6).
807 * The last two options are for peer's information only.
808 */
809 {
810 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
811 .is_local = false,
812 .is_mandatory = false,
813 .val = 0
814 },
815 {
816 .dependent_feat = DCCPF_SEND_LEV_RATE,
817 .is_local = false,
818 .is_mandatory = true,
819 .val = 1
820 },
821 { /* this CCID does not support Ack Ratio */
822 .dependent_feat = DCCPF_ACK_RATIO,
823 .is_local = true,
824 .is_mandatory = false,
825 .val = 0
826 },
827 { /* tell receiver we are sending NDP counts */
828 .dependent_feat = DCCPF_SEND_NDP_COUNT,
829 .is_local = true,
830 .is_mandatory = false,
831 .val = 1
832 },
833 { 0, 0, 0, 0 }
834 }
835 };
836 switch (ccid) {
837 case DCCPC_CCID2:
838 return ccid2_dependencies[is_local];
839 case DCCPC_CCID3:
840 return ccid3_dependencies[is_local];
841 default:
842 return NULL;
843 }
844}
845
846/**
847 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
848 * @fn: feature-negotiation list to update
849 * @id: CCID number to track
850 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
851 * This function needs to be called after registering all other features.
852 */
853static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
854{
855 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
856 int i, rc = (table == NULL);
857
858 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
859 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
860 rc = __feat_register_sp(fn, table[i].dependent_feat,
861 table[i].is_local,
862 table[i].is_mandatory,
863 &table[i].val, 1);
864 else
865 rc = __feat_register_nn(fn, table[i].dependent_feat,
866 table[i].is_mandatory,
867 table[i].val);
868 return rc;
869}
870
871/**
872 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
873 * @dp: client or listening socket (settings will be inherited)
874 * This is called after all registrations (socket initialisation, sysctls, and
875 * sockopt calls), and before sending the first packet containing Change options
876 * (ie. client-Request or server-Response), to ensure internal consistency.
877 */
878int dccp_feat_finalise_settings(struct dccp_sock *dp)
879{
880 struct list_head *fn = &dp->dccps_featneg;
881 struct dccp_feat_entry *entry;
882 int i = 2, ccids[2] = { -1, -1 };
883
884 /*
885 * Propagating CCIDs:
886 * 1) not useful to propagate CCID settings if this host advertises more
887 * than one CCID: the choice of CCID may still change - if this is
888 * the client, or if this is the server and the client sends
889 * singleton CCID values.
890 * 2) since is that propagate_ccid changes the list, we defer changing
891 * the sorted list until after the traversal.
892 */
893 list_for_each_entry(entry, fn, node)
894 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
895 ccids[entry->is_local] = entry->val.sp.vec[0];
896 while (i--)
897 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
898 return -1;
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000899 dccp_feat_print_fnlist(fn);
Gerrit Renker9eca0a42008-11-12 00:48:44 -0800900 return 0;
901}
902
Gerrit Renker0c116832008-11-16 22:49:52 -0800903/**
904 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
905 * It is the server which resolves the dependencies once the CCID has been
906 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
907 */
908int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
909{
910 struct list_head *fn = &dreq->dreq_featneg;
911 struct dccp_feat_entry *entry;
912 u8 is_local, ccid;
913
914 for (is_local = 0; is_local <= 1; is_local++) {
915 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
916
917 if (entry != NULL && !entry->empty_confirm)
918 ccid = entry->val.sp.vec[0];
919 else
920 ccid = dccp_feat_default_value(DCCPF_CCID);
921
922 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
923 return -1;
924 }
925 return 0;
926}
927
Gerrit Renker75757a72008-12-01 23:31:04 -0800928/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
929static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
930{
931 u8 c, s;
932
933 for (s = 0; s < slen; s++)
934 for (c = 0; c < clen; c++)
935 if (servlist[s] == clilist[c])
936 return servlist[s];
937 return -1;
938}
939
940/**
941 * dccp_feat_prefer - Move preferred entry to the start of array
942 * Reorder the @array_len elements in @array so that @preferred_value comes
943 * first. Returns >0 to indicate that @preferred_value does occur in @array.
944 */
945static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
946{
947 u8 i, does_occur = 0;
948
949 if (array != NULL) {
950 for (i = 0; i < array_len; i++)
951 if (array[i] == preferred_value) {
952 array[i] = array[0];
953 does_occur++;
954 }
955 if (does_occur)
956 array[0] = preferred_value;
957 }
958 return does_occur;
959}
960
961/**
962 * dccp_feat_reconcile - Reconcile SP preference lists
963 * @fval: SP list to reconcile into
964 * @arr: received SP preference list
965 * @len: length of @arr in bytes
966 * @is_server: whether this side is the server (and @fv is the server's list)
967 * @reorder: whether to reorder the list in @fv after reconciling with @arr
968 * When successful, > 0 is returned and the reconciled list is in @fval.
969 * A value of 0 means that negotiation failed (no shared entry).
970 */
971static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
972 bool is_server, bool reorder)
973{
974 int rc;
975
976 if (!fv->sp.vec || !arr) {
977 DCCP_CRIT("NULL feature value or array");
978 return 0;
979 }
980
981 if (is_server)
982 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
983 else
984 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
985
986 if (!reorder)
987 return rc;
988 if (rc < 0)
989 return 0;
990
991 /*
992 * Reorder list: used for activating features and in dccp_insert_fn_opt.
993 */
994 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
995}
996
Gerrit Renkere77b8362008-12-01 23:32:35 -0800997/**
998 * dccp_feat_change_recv - Process incoming ChangeL/R options
999 * @fn: feature-negotiation list to update
1000 * @is_mandatory: whether the Change was preceded by a Mandatory option
1001 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
1002 * @feat: one of %dccp_feature_numbers
1003 * @val: NN value or SP value/preference list
1004 * @len: length of @val in bytes
1005 * @server: whether this node is the server (1) or the client (0)
1006 */
1007static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1008 u8 feat, u8 *val, u8 len, const bool server)
1009{
1010 u8 defval, type = dccp_feat_type(feat);
1011 const bool local = (opt == DCCPO_CHANGE_R);
1012 struct dccp_feat_entry *entry;
1013 dccp_feat_val fval;
1014
1015 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
1016 goto unknown_feature_or_value;
1017
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001018 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1019
Gerrit Renkere77b8362008-12-01 23:32:35 -08001020 /*
1021 * Negotiation of NN features: Change R is invalid, so there is no
1022 * simultaneous negotiation; hence we do not look up in the list.
1023 */
1024 if (type == FEAT_NN) {
1025 if (local || len > sizeof(fval.nn))
1026 goto unknown_feature_or_value;
1027
1028 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1029 fval.nn = dccp_decode_value_var(val, len);
1030 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1031 goto unknown_feature_or_value;
1032
1033 return dccp_feat_push_confirm(fn, feat, local, &fval);
1034 }
1035
1036 /*
1037 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
1038 */
1039 entry = dccp_feat_list_lookup(fn, feat, local);
1040 if (entry == NULL) {
1041 /*
1042 * No particular preferences have been registered. We deal with
1043 * this situation by assuming that all valid values are equally
1044 * acceptable, and apply the following checks:
1045 * - if the peer's list is a singleton, we accept a valid value;
1046 * - if we are the server, we first try to see if the peer (the
1047 * client) advertises the default value. If yes, we use it,
1048 * otherwise we accept the preferred value;
1049 * - else if we are the client, we use the first list element.
1050 */
1051 if (dccp_feat_clone_sp_val(&fval, val, 1))
1052 return DCCP_RESET_CODE_TOO_BUSY;
1053
1054 if (len > 1 && server) {
1055 defval = dccp_feat_default_value(feat);
1056 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1057 fval.sp.vec[0] = defval;
1058 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1059 kfree(fval.sp.vec);
1060 goto unknown_feature_or_value;
1061 }
1062
1063 /* Treat unsupported CCIDs like invalid values */
1064 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1065 kfree(fval.sp.vec);
1066 goto not_valid_or_not_known;
1067 }
1068
1069 return dccp_feat_push_confirm(fn, feat, local, &fval);
1070
1071 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
1072 return 0;
1073 }
1074
1075 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1076 entry->empty_confirm = 0;
1077 } else if (is_mandatory) {
1078 return DCCP_RESET_CODE_MANDATORY_ERROR;
1079 } else if (entry->state == FEAT_INITIALISING) {
1080 /*
1081 * Failed simultaneous negotiation (server only): try to `save'
1082 * the connection by checking whether entry contains the default
1083 * value for @feat. If yes, send an empty Confirm to signal that
1084 * the received Change was not understood - which implies using
1085 * the default value.
1086 * If this also fails, we use Reset as the last resort.
1087 */
1088 WARN_ON(!server);
1089 defval = dccp_feat_default_value(feat);
1090 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1091 return DCCP_RESET_CODE_OPTION_ERROR;
1092 entry->empty_confirm = 1;
1093 }
1094 entry->needs_confirm = 1;
1095 entry->needs_mandatory = 0;
1096 entry->state = FEAT_STABLE;
1097 return 0;
1098
1099unknown_feature_or_value:
1100 if (!is_mandatory)
1101 return dccp_push_empty_confirm(fn, feat, local);
1102
1103not_valid_or_not_known:
1104 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1105 : DCCP_RESET_CODE_OPTION_ERROR;
1106}
1107
1108/**
Gerrit Renkerb1ad0042008-12-01 23:33:18 -08001109 * dccp_feat_confirm_recv - Process received Confirm options
1110 * @fn: feature-negotiation list to update
1111 * @is_mandatory: whether @opt was preceded by a Mandatory option
1112 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
1113 * @feat: one of %dccp_feature_numbers
1114 * @val: NN value or SP value/preference list
1115 * @len: length of @val in bytes
1116 * @server: whether this node is server (1) or client (0)
1117 */
1118static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1119 u8 feat, u8 *val, u8 len, const bool server)
1120{
1121 u8 *plist, plen, type = dccp_feat_type(feat);
1122 const bool local = (opt == DCCPO_CONFIRM_R);
1123 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1124
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001125 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1126
Gerrit Renkerb1ad0042008-12-01 23:33:18 -08001127 if (entry == NULL) { /* nothing queued: ignore or handle error */
1128 if (is_mandatory && type == FEAT_UNKNOWN)
1129 return DCCP_RESET_CODE_MANDATORY_ERROR;
1130
1131 if (!local && type == FEAT_NN) /* 6.3.2 */
1132 goto confirmation_failed;
1133 return 0;
1134 }
1135
1136 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1137 return 0;
1138
1139 if (len == 0) {
1140 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1141 goto confirmation_failed;
1142 /*
1143 * Empty Confirm during connection setup: this means reverting
1144 * to the `old' value, which in this case is the default. Since
1145 * we handle default values automatically when no other values
1146 * have been set, we revert to the old value by removing this
1147 * entry from the list.
1148 */
1149 dccp_feat_list_pop(entry);
1150 return 0;
1151 }
1152
1153 if (type == FEAT_NN) {
1154 if (len > sizeof(entry->val.nn))
1155 goto confirmation_failed;
1156
1157 if (entry->val.nn == dccp_decode_value_var(val, len))
1158 goto confirmation_succeeded;
1159
1160 DCCP_WARN("Bogus Confirm for non-existing value\n");
1161 goto confirmation_failed;
1162 }
1163
1164 /*
1165 * Parsing SP Confirms: the first element of @val is the preferred
1166 * SP value which the peer confirms, the remainder depends on @len.
1167 * Note that only the confirmed value need to be a valid SP value.
1168 */
1169 if (!dccp_feat_is_valid_sp_val(feat, *val))
1170 goto confirmation_failed;
1171
1172 if (len == 1) { /* peer didn't supply a preference list */
1173 plist = val;
1174 plen = len;
1175 } else { /* preferred value + preference list */
1176 plist = val + 1;
1177 plen = len - 1;
1178 }
1179
1180 /* Check whether the peer got the reconciliation right (6.6.8) */
1181 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1182 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1183 return DCCP_RESET_CODE_OPTION_ERROR;
1184 }
1185 entry->val.sp.vec[0] = *val;
1186
1187confirmation_succeeded:
1188 entry->state = FEAT_STABLE;
1189 return 0;
1190
1191confirmation_failed:
1192 DCCP_WARN("Confirmation failed\n");
1193 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1194 : DCCP_RESET_CODE_OPTION_ERROR;
1195}
1196
1197/**
Gerrit Renkere77b8362008-12-01 23:32:35 -08001198 * dccp_feat_parse_options - Process Feature-Negotiation Options
1199 * @sk: for general use and used by the client during connection setup
1200 * @dreq: used by the server during connection setup
1201 * @mandatory: whether @opt was preceded by a Mandatory option
1202 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1203 * @feat: one of %dccp_feature_numbers
1204 * @val: value contents of @opt
1205 * @len: length of @val in bytes
1206 * Returns 0 on success, a Reset code for ending the connection otherwise.
1207 */
1208int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1209 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1210{
1211 struct dccp_sock *dp = dccp_sk(sk);
1212 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1213 bool server = false;
1214
1215 switch (sk->sk_state) {
1216 /*
1217 * Negotiation during connection setup
1218 */
1219 case DCCP_LISTEN:
1220 server = true; /* fall through */
1221 case DCCP_REQUESTING:
1222 switch (opt) {
1223 case DCCPO_CHANGE_L:
1224 case DCCPO_CHANGE_R:
1225 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1226 val, len, server);
Gerrit Renkerb1ad0042008-12-01 23:33:18 -08001227 case DCCPO_CONFIRM_R:
1228 case DCCPO_CONFIRM_L:
1229 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1230 val, len, server);
Gerrit Renkere77b8362008-12-01 23:32:35 -08001231 }
1232 }
1233 return 0; /* ignore FN options in all other states */
1234}
1235
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001236/**
1237 * dccp_feat_init - Seed feature negotiation with host-specific defaults
1238 * This initialises global defaults, depending on the value of the sysctls.
1239 * These can later be overridden by registering changes via setsockopt calls.
1240 * The last link in the chain is finalise_settings, to make sure that between
1241 * here and the start of actual feature negotiation no inconsistencies enter.
1242 *
1243 * All features not appearing below use either defaults or are otherwise
1244 * later adjusted through dccp_feat_finalise_settings().
1245 */
Gerrit Renkere8ef9672008-11-12 00:43:40 -08001246int dccp_feat_init(struct sock *sk)
Andrea Bittauafe00252006-03-20 17:43:56 -08001247{
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001248 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1249 u8 on = 1, off = 0;
Andrea Bittauafe00252006-03-20 17:43:56 -08001250 int rc;
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001251 struct {
1252 u8 *val;
1253 u8 len;
1254 } tx, rx;
Andrea Bittauafe00252006-03-20 17:43:56 -08001255
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001256 /* Non-negotiable (NN) features */
1257 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
Gerrit Renker883ca832009-01-16 23:36:32 +00001258 sysctl_dccp_sequence_window);
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001259 if (rc)
1260 return rc;
Andrea Bittauafe00252006-03-20 17:43:56 -08001261
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001262 /* Server-priority (SP) features */
1263
1264 /* Advertise that short seqnos are not supported (7.6.1) */
1265 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
1266 if (rc)
1267 return rc;
1268
1269 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
1270 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
1271 if (rc)
1272 return rc;
1273
1274 /*
1275 * We advertise the available list of CCIDs and reorder according to
1276 * preferences, to avoid failure resulting from negotiating different
1277 * singleton values (which always leads to failure).
1278 * These settings can still (later) be overridden via sockopts.
1279 */
1280 if (ccid_get_builtin_ccids(&tx.val, &tx.len) ||
1281 ccid_get_builtin_ccids(&rx.val, &rx.len))
1282 return -ENOBUFS;
1283
Gerrit Renker883ca832009-01-16 23:36:32 +00001284 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
1285 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001286 goto free_ccid_lists;
1287
1288 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
1289 if (rc)
1290 goto free_ccid_lists;
1291
1292 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
1293
1294free_ccid_lists:
1295 kfree(tx.val);
1296 kfree(rx.val);
Andrea Bittauafe00252006-03-20 17:43:56 -08001297 return rc;
1298}
1299
Gerrit Renker422d9cd2008-12-01 23:34:01 -08001300int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1301{
1302 struct dccp_sock *dp = dccp_sk(sk);
1303 struct dccp_feat_entry *cur, *next;
1304 int idx;
1305 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1306 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1307 };
1308
1309 list_for_each_entry(cur, fn_list, node) {
1310 /*
1311 * An empty Confirm means that either an unknown feature type
1312 * or an invalid value was present. In the first case there is
1313 * nothing to activate, in the other the default value is used.
1314 */
1315 if (cur->empty_confirm)
1316 continue;
1317
1318 idx = dccp_feat_index(cur->feat_num);
1319 if (idx < 0) {
1320 DCCP_BUG("Unknown feature %u", cur->feat_num);
1321 goto activation_failed;
1322 }
1323 if (cur->state != FEAT_STABLE) {
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001324 DCCP_CRIT("Negotiation of %s %s failed in state %s",
Gerrit Renker422d9cd2008-12-01 23:34:01 -08001325 cur->is_local ? "local" : "remote",
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001326 dccp_feat_fname(cur->feat_num),
1327 dccp_feat_sname[cur->state]);
Gerrit Renker422d9cd2008-12-01 23:34:01 -08001328 goto activation_failed;
1329 }
1330 fvals[idx][cur->is_local] = &cur->val;
1331 }
1332
1333 /*
1334 * Activate in decreasing order of index, so that the CCIDs are always
1335 * activated as the last feature. This avoids the case where a CCID
1336 * relies on the initialisation of one or more features that it depends
1337 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1338 */
1339 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1340 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1341 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1342 DCCP_CRIT("Could not activate %d", idx);
1343 goto activation_failed;
1344 }
1345
1346 /* Clean up Change options which have been confirmed already */
1347 list_for_each_entry_safe(cur, next, fn_list, node)
1348 if (!cur->needs_confirm)
1349 dccp_feat_list_pop(cur);
1350
1351 dccp_pr_debug("Activation OK\n");
1352 return 0;
1353
1354activation_failed:
1355 /*
1356 * We clean up everything that may have been allocated, since
1357 * it is difficult to track at which stage negotiation failed.
1358 * This is ok, since all allocation functions below are robust
1359 * against NULL arguments.
1360 */
1361 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1362 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1363 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1364 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1365 dp->dccps_hc_rx_ackvec = NULL;
1366 return -1;
1367}