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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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090025#include <linux/slab.h>
Andrea Bittau6ffd30f2006-03-20 19:22:37 -080026#include "ccid.h"
Andrea Bittauafe00252006-03-20 17:43:56 -080027#include "feat.h"
28
Gerrit Renker883ca832009-01-16 23:36:32 +000029/* 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
Gerrit Renker422d9cd2008-12-01 23:34:01 -080034/*
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);
Gerrit Renkere5fd56c2009-01-04 21:43:23 -080043 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
Gerrit Renker422d9cd2008-12-01 23:34:01 -080044
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{
Gerrit Renker792b4872009-01-16 23:36:31 +000060 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 }
Gerrit Renker422d9cd2008-12-01 23:34:01 -080071 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)
Gerrit Renker4098dce2008-12-08 01:18:37 -0800103 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800104 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
Gerrit Renker7d43d1a02008-11-04 23:43:47 -0800132static 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 */
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800137 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
Gerrit Renker7d43d1a02008-11-04 23:43:47 -0800138/*
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[] = {
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800157 { 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 },
Gerrit Renker7d43d1a02008-11-04 23:43:47 -0800167};
168#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
169
Gerrit Renker61e64732008-11-04 23:54:04 -0800170/**
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
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800200static 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
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000212/*
213 * Debugging and verbose-printing section
214 */
215static const char *dccp_feat_fname(const u8 feat)
216{
Jan Engelhardt36cbd3d2009-08-05 10:42:58 -0700217 static const char *const feature_names[] = {
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000218 [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
Jan Engelhardt36cbd3d2009-08-05 10:42:58 -0700240static const char *const dccp_feat_sname[] = {
241 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
242};
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000243
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
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800307static 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
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000339 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
Gerrit Renker422d9cd2008-12-01 23:34:01 -0800343 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
344}
345
Gerrit Renkerb1ad0042008-12-01 23:33:18 -0800346/* 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
Gerrit Renkerac757732008-11-04 23:55:49 -0800353/* 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
Gerrit Renker61e64732008-11-04 23:54:04 -0800367static 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
Gerrit Renkerac757732008-11-04 23:55:49 -0800376static 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
Gerrit Renker61e64732008-11-04 23:54:04 -0800398static 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 */
Gerrit Renker0c116832008-11-16 22:49:52 -0800415static 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
Gerrit Renker3d3e35a2008-11-20 01:03:08 -0800420 list_for_each_entry(entry, fn_list, node) {
Gerrit Renker0c116832008-11-16 22:49:52 -0800421 if (entry->feat_num == feat_num && entry->is_local == is_local)
422 return entry;
423 else if (entry->feat_num > feat_num)
424 break;
Gerrit Renker3d3e35a2008-11-20 01:03:08 -0800425 }
Gerrit Renker0c116832008-11-16 22:49:52 -0800426 return NULL;
427}
Gerrit Renker61e64732008-11-04 23:54:04 -0800428
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800429/**
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
Gerrit Renkere77b8362008-12-01 23:32:35 -0800486/**
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
Gerrit Renker61e64732008-11-04 23:54:04 -0800520static 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
Gerrit Renkerac757732008-11-04 23:55:49 -0800536/* 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
Gerrit Renker0971d172008-12-01 23:27:31 -0800555/**
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
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800569static 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/**
Gerrit Renker0971d172008-12-01 23:27:31 -0800611 * 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 }
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000647 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
Gerrit Renker0971d172008-12-01 23:27:31 -0800648
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/**
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800663 * __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
Gerrit Renkerd90ebcb2008-11-12 00:47:26 -0800704 /* 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
Gerrit Renkere8ef9672008-11-12 00:43:40 -0800708 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
Gerrit Renker49aebc62008-11-16 22:51:23 -0800714/**
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)
Chris Wright19443172008-05-05 13:50:24 -0700728 return -EINVAL;
Gerrit Renker49aebc62008-11-16 22:51:23 -0800729 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
730 0, list, len);
Andrea Bittauafe00252006-03-20 17:43:56 -0800731}
732
Gerrit Renker49aebc62008-11-16 22:51:23 -0800733/* Analogous to dccp_feat_register_sp(), but for non-negotiable values */
734int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val)
735{
736 /* any changes must be registered before establishing the connection */
737 if (sk->sk_state != DCCP_CLOSED)
738 return -EISCONN;
739 if (dccp_feat_type(feat) != FEAT_NN)
740 return -EINVAL;
741 return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val);
742}
Andrea Bittauafe00252006-03-20 17:43:56 -0800743
Gerrit Renker9eca0a42008-11-12 00:48:44 -0800744/*
745 * Tracking features whose value depend on the choice of CCID
746 *
747 * This is designed with an extension in mind so that a list walk could be done
748 * before activating any features. However, the existing framework was found to
749 * work satisfactorily up until now, the automatic verification is left open.
750 * When adding new CCIDs, add a corresponding dependency table here.
751 */
752static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
753{
754 static const struct ccid_dependency ccid2_dependencies[2][2] = {
755 /*
756 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
757 * feature and Send Ack Vector is an RX feature, `is_local'
758 * needs to be reversed.
759 */
760 { /* Dependencies of the receiver-side (remote) CCID2 */
761 {
762 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
763 .is_local = true,
764 .is_mandatory = true,
765 .val = 1
766 },
767 { 0, 0, 0, 0 }
768 },
769 { /* Dependencies of the sender-side (local) CCID2 */
770 {
771 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
772 .is_local = false,
773 .is_mandatory = true,
774 .val = 1
775 },
776 { 0, 0, 0, 0 }
777 }
778 };
779 static const struct ccid_dependency ccid3_dependencies[2][5] = {
780 { /*
781 * Dependencies of the receiver-side CCID3
782 */
783 { /* locally disable Ack Vectors */
784 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
785 .is_local = true,
786 .is_mandatory = false,
787 .val = 0
788 },
789 { /* see below why Send Loss Event Rate is on */
790 .dependent_feat = DCCPF_SEND_LEV_RATE,
791 .is_local = true,
792 .is_mandatory = true,
793 .val = 1
794 },
795 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
796 .dependent_feat = DCCPF_SEND_NDP_COUNT,
797 .is_local = false,
798 .is_mandatory = true,
799 .val = 1
800 },
801 { 0, 0, 0, 0 },
802 },
803 { /*
804 * CCID3 at the TX side: we request that the HC-receiver
805 * will not send Ack Vectors (they will be ignored, so
806 * Mandatory is not set); we enable Send Loss Event Rate
807 * (Mandatory since the implementation does not support
808 * the Loss Intervals option of RFC 4342, 8.6).
809 * The last two options are for peer's information only.
810 */
811 {
812 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
813 .is_local = false,
814 .is_mandatory = false,
815 .val = 0
816 },
817 {
818 .dependent_feat = DCCPF_SEND_LEV_RATE,
819 .is_local = false,
820 .is_mandatory = true,
821 .val = 1
822 },
823 { /* this CCID does not support Ack Ratio */
824 .dependent_feat = DCCPF_ACK_RATIO,
825 .is_local = true,
826 .is_mandatory = false,
827 .val = 0
828 },
829 { /* tell receiver we are sending NDP counts */
830 .dependent_feat = DCCPF_SEND_NDP_COUNT,
831 .is_local = true,
832 .is_mandatory = false,
833 .val = 1
834 },
835 { 0, 0, 0, 0 }
836 }
837 };
838 switch (ccid) {
839 case DCCPC_CCID2:
840 return ccid2_dependencies[is_local];
841 case DCCPC_CCID3:
842 return ccid3_dependencies[is_local];
843 default:
844 return NULL;
845 }
846}
847
848/**
849 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
850 * @fn: feature-negotiation list to update
851 * @id: CCID number to track
852 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
853 * This function needs to be called after registering all other features.
854 */
855static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
856{
857 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
858 int i, rc = (table == NULL);
859
860 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
861 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
862 rc = __feat_register_sp(fn, table[i].dependent_feat,
863 table[i].is_local,
864 table[i].is_mandatory,
865 &table[i].val, 1);
866 else
867 rc = __feat_register_nn(fn, table[i].dependent_feat,
868 table[i].is_mandatory,
869 table[i].val);
870 return rc;
871}
872
873/**
874 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
875 * @dp: client or listening socket (settings will be inherited)
876 * This is called after all registrations (socket initialisation, sysctls, and
877 * sockopt calls), and before sending the first packet containing Change options
878 * (ie. client-Request or server-Response), to ensure internal consistency.
879 */
880int dccp_feat_finalise_settings(struct dccp_sock *dp)
881{
882 struct list_head *fn = &dp->dccps_featneg;
883 struct dccp_feat_entry *entry;
884 int i = 2, ccids[2] = { -1, -1 };
885
886 /*
887 * Propagating CCIDs:
888 * 1) not useful to propagate CCID settings if this host advertises more
889 * than one CCID: the choice of CCID may still change - if this is
890 * the client, or if this is the server and the client sends
891 * singleton CCID values.
892 * 2) since is that propagate_ccid changes the list, we defer changing
893 * the sorted list until after the traversal.
894 */
895 list_for_each_entry(entry, fn, node)
896 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
897 ccids[entry->is_local] = entry->val.sp.vec[0];
898 while (i--)
899 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
900 return -1;
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +0000901 dccp_feat_print_fnlist(fn);
Gerrit Renker9eca0a42008-11-12 00:48:44 -0800902 return 0;
903}
904
Gerrit Renker0c116832008-11-16 22:49:52 -0800905/**
906 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
907 * It is the server which resolves the dependencies once the CCID has been
908 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
909 */
910int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
911{
912 struct list_head *fn = &dreq->dreq_featneg;
913 struct dccp_feat_entry *entry;
914 u8 is_local, ccid;
915
916 for (is_local = 0; is_local <= 1; is_local++) {
917 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
918
919 if (entry != NULL && !entry->empty_confirm)
920 ccid = entry->val.sp.vec[0];
921 else
922 ccid = dccp_feat_default_value(DCCPF_CCID);
923
924 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
925 return -1;
926 }
927 return 0;
928}
929
Gerrit Renker75757a72008-12-01 23:31:04 -0800930/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
931static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
932{
933 u8 c, s;
934
935 for (s = 0; s < slen; s++)
936 for (c = 0; c < clen; c++)
937 if (servlist[s] == clilist[c])
938 return servlist[s];
939 return -1;
940}
941
942/**
943 * dccp_feat_prefer - Move preferred entry to the start of array
944 * Reorder the @array_len elements in @array so that @preferred_value comes
945 * first. Returns >0 to indicate that @preferred_value does occur in @array.
946 */
947static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
948{
949 u8 i, does_occur = 0;
950
951 if (array != NULL) {
952 for (i = 0; i < array_len; i++)
953 if (array[i] == preferred_value) {
954 array[i] = array[0];
955 does_occur++;
956 }
957 if (does_occur)
958 array[0] = preferred_value;
959 }
960 return does_occur;
961}
962
963/**
964 * dccp_feat_reconcile - Reconcile SP preference lists
965 * @fval: SP list to reconcile into
966 * @arr: received SP preference list
967 * @len: length of @arr in bytes
968 * @is_server: whether this side is the server (and @fv is the server's list)
969 * @reorder: whether to reorder the list in @fv after reconciling with @arr
970 * When successful, > 0 is returned and the reconciled list is in @fval.
971 * A value of 0 means that negotiation failed (no shared entry).
972 */
973static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
974 bool is_server, bool reorder)
975{
976 int rc;
977
978 if (!fv->sp.vec || !arr) {
979 DCCP_CRIT("NULL feature value or array");
980 return 0;
981 }
982
983 if (is_server)
984 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
985 else
986 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
987
988 if (!reorder)
989 return rc;
990 if (rc < 0)
991 return 0;
992
993 /*
994 * Reorder list: used for activating features and in dccp_insert_fn_opt.
995 */
996 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
997}
998
Gerrit Renkere77b8362008-12-01 23:32:35 -0800999/**
1000 * dccp_feat_change_recv - Process incoming ChangeL/R options
1001 * @fn: feature-negotiation list to update
1002 * @is_mandatory: whether the Change was preceded by a Mandatory option
1003 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
1004 * @feat: one of %dccp_feature_numbers
1005 * @val: NN value or SP value/preference list
1006 * @len: length of @val in bytes
1007 * @server: whether this node is the server (1) or the client (0)
1008 */
1009static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1010 u8 feat, u8 *val, u8 len, const bool server)
1011{
1012 u8 defval, type = dccp_feat_type(feat);
1013 const bool local = (opt == DCCPO_CHANGE_R);
1014 struct dccp_feat_entry *entry;
1015 dccp_feat_val fval;
1016
1017 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
1018 goto unknown_feature_or_value;
1019
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001020 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1021
Gerrit Renkere77b8362008-12-01 23:32:35 -08001022 /*
1023 * Negotiation of NN features: Change R is invalid, so there is no
1024 * simultaneous negotiation; hence we do not look up in the list.
1025 */
1026 if (type == FEAT_NN) {
1027 if (local || len > sizeof(fval.nn))
1028 goto unknown_feature_or_value;
1029
1030 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1031 fval.nn = dccp_decode_value_var(val, len);
1032 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1033 goto unknown_feature_or_value;
1034
1035 return dccp_feat_push_confirm(fn, feat, local, &fval);
1036 }
1037
1038 /*
1039 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
1040 */
1041 entry = dccp_feat_list_lookup(fn, feat, local);
1042 if (entry == NULL) {
1043 /*
1044 * No particular preferences have been registered. We deal with
1045 * this situation by assuming that all valid values are equally
1046 * acceptable, and apply the following checks:
1047 * - if the peer's list is a singleton, we accept a valid value;
1048 * - if we are the server, we first try to see if the peer (the
1049 * client) advertises the default value. If yes, we use it,
1050 * otherwise we accept the preferred value;
1051 * - else if we are the client, we use the first list element.
1052 */
1053 if (dccp_feat_clone_sp_val(&fval, val, 1))
1054 return DCCP_RESET_CODE_TOO_BUSY;
1055
1056 if (len > 1 && server) {
1057 defval = dccp_feat_default_value(feat);
1058 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1059 fval.sp.vec[0] = defval;
1060 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1061 kfree(fval.sp.vec);
1062 goto unknown_feature_or_value;
1063 }
1064
1065 /* Treat unsupported CCIDs like invalid values */
1066 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1067 kfree(fval.sp.vec);
1068 goto not_valid_or_not_known;
1069 }
1070
1071 return dccp_feat_push_confirm(fn, feat, local, &fval);
1072
1073 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
1074 return 0;
1075 }
1076
1077 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1078 entry->empty_confirm = 0;
1079 } else if (is_mandatory) {
1080 return DCCP_RESET_CODE_MANDATORY_ERROR;
1081 } else if (entry->state == FEAT_INITIALISING) {
1082 /*
1083 * Failed simultaneous negotiation (server only): try to `save'
1084 * the connection by checking whether entry contains the default
1085 * value for @feat. If yes, send an empty Confirm to signal that
1086 * the received Change was not understood - which implies using
1087 * the default value.
1088 * If this also fails, we use Reset as the last resort.
1089 */
1090 WARN_ON(!server);
1091 defval = dccp_feat_default_value(feat);
1092 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1093 return DCCP_RESET_CODE_OPTION_ERROR;
1094 entry->empty_confirm = 1;
1095 }
1096 entry->needs_confirm = 1;
1097 entry->needs_mandatory = 0;
1098 entry->state = FEAT_STABLE;
1099 return 0;
1100
1101unknown_feature_or_value:
1102 if (!is_mandatory)
1103 return dccp_push_empty_confirm(fn, feat, local);
1104
1105not_valid_or_not_known:
1106 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1107 : DCCP_RESET_CODE_OPTION_ERROR;
1108}
1109
1110/**
Gerrit Renkerb1ad0042008-12-01 23:33:18 -08001111 * dccp_feat_confirm_recv - Process received Confirm options
1112 * @fn: feature-negotiation list to update
1113 * @is_mandatory: whether @opt was preceded by a Mandatory option
1114 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
1115 * @feat: one of %dccp_feature_numbers
1116 * @val: NN value or SP value/preference list
1117 * @len: length of @val in bytes
1118 * @server: whether this node is server (1) or client (0)
1119 */
1120static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1121 u8 feat, u8 *val, u8 len, const bool server)
1122{
1123 u8 *plist, plen, type = dccp_feat_type(feat);
1124 const bool local = (opt == DCCPO_CONFIRM_R);
1125 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1126
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001127 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1128
Gerrit Renkerb1ad0042008-12-01 23:33:18 -08001129 if (entry == NULL) { /* nothing queued: ignore or handle error */
1130 if (is_mandatory && type == FEAT_UNKNOWN)
1131 return DCCP_RESET_CODE_MANDATORY_ERROR;
1132
1133 if (!local && type == FEAT_NN) /* 6.3.2 */
1134 goto confirmation_failed;
1135 return 0;
1136 }
1137
1138 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1139 return 0;
1140
1141 if (len == 0) {
1142 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1143 goto confirmation_failed;
1144 /*
1145 * Empty Confirm during connection setup: this means reverting
1146 * to the `old' value, which in this case is the default. Since
1147 * we handle default values automatically when no other values
1148 * have been set, we revert to the old value by removing this
1149 * entry from the list.
1150 */
1151 dccp_feat_list_pop(entry);
1152 return 0;
1153 }
1154
1155 if (type == FEAT_NN) {
1156 if (len > sizeof(entry->val.nn))
1157 goto confirmation_failed;
1158
1159 if (entry->val.nn == dccp_decode_value_var(val, len))
1160 goto confirmation_succeeded;
1161
1162 DCCP_WARN("Bogus Confirm for non-existing value\n");
1163 goto confirmation_failed;
1164 }
1165
1166 /*
1167 * Parsing SP Confirms: the first element of @val is the preferred
1168 * SP value which the peer confirms, the remainder depends on @len.
1169 * Note that only the confirmed value need to be a valid SP value.
1170 */
1171 if (!dccp_feat_is_valid_sp_val(feat, *val))
1172 goto confirmation_failed;
1173
1174 if (len == 1) { /* peer didn't supply a preference list */
1175 plist = val;
1176 plen = len;
1177 } else { /* preferred value + preference list */
1178 plist = val + 1;
1179 plen = len - 1;
1180 }
1181
1182 /* Check whether the peer got the reconciliation right (6.6.8) */
1183 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1184 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1185 return DCCP_RESET_CODE_OPTION_ERROR;
1186 }
1187 entry->val.sp.vec[0] = *val;
1188
1189confirmation_succeeded:
1190 entry->state = FEAT_STABLE;
1191 return 0;
1192
1193confirmation_failed:
1194 DCCP_WARN("Confirmation failed\n");
1195 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1196 : DCCP_RESET_CODE_OPTION_ERROR;
1197}
1198
1199/**
Gerrit Renkere77b8362008-12-01 23:32:35 -08001200 * dccp_feat_parse_options - Process Feature-Negotiation Options
1201 * @sk: for general use and used by the client during connection setup
1202 * @dreq: used by the server during connection setup
1203 * @mandatory: whether @opt was preceded by a Mandatory option
1204 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1205 * @feat: one of %dccp_feature_numbers
1206 * @val: value contents of @opt
1207 * @len: length of @val in bytes
1208 * Returns 0 on success, a Reset code for ending the connection otherwise.
1209 */
1210int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1211 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1212{
1213 struct dccp_sock *dp = dccp_sk(sk);
1214 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1215 bool server = false;
1216
1217 switch (sk->sk_state) {
1218 /*
1219 * Negotiation during connection setup
1220 */
1221 case DCCP_LISTEN:
1222 server = true; /* fall through */
1223 case DCCP_REQUESTING:
1224 switch (opt) {
1225 case DCCPO_CHANGE_L:
1226 case DCCPO_CHANGE_R:
1227 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1228 val, len, server);
Gerrit Renkerb1ad0042008-12-01 23:33:18 -08001229 case DCCPO_CONFIRM_R:
1230 case DCCPO_CONFIRM_L:
1231 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1232 val, len, server);
Gerrit Renkere77b8362008-12-01 23:32:35 -08001233 }
1234 }
1235 return 0; /* ignore FN options in all other states */
1236}
1237
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001238/**
1239 * dccp_feat_init - Seed feature negotiation with host-specific defaults
1240 * This initialises global defaults, depending on the value of the sysctls.
1241 * These can later be overridden by registering changes via setsockopt calls.
1242 * The last link in the chain is finalise_settings, to make sure that between
1243 * here and the start of actual feature negotiation no inconsistencies enter.
1244 *
1245 * All features not appearing below use either defaults or are otherwise
1246 * later adjusted through dccp_feat_finalise_settings().
1247 */
Gerrit Renkere8ef9672008-11-12 00:43:40 -08001248int dccp_feat_init(struct sock *sk)
Andrea Bittauafe00252006-03-20 17:43:56 -08001249{
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001250 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1251 u8 on = 1, off = 0;
Andrea Bittauafe00252006-03-20 17:43:56 -08001252 int rc;
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001253 struct {
1254 u8 *val;
1255 u8 len;
1256 } tx, rx;
Andrea Bittauafe00252006-03-20 17:43:56 -08001257
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001258 /* Non-negotiable (NN) features */
1259 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
Gerrit Renker883ca832009-01-16 23:36:32 +00001260 sysctl_dccp_sequence_window);
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001261 if (rc)
1262 return rc;
Andrea Bittauafe00252006-03-20 17:43:56 -08001263
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001264 /* Server-priority (SP) features */
1265
1266 /* Advertise that short seqnos are not supported (7.6.1) */
1267 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
1268 if (rc)
1269 return rc;
1270
1271 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
1272 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
1273 if (rc)
1274 return rc;
1275
1276 /*
1277 * We advertise the available list of CCIDs and reorder according to
1278 * preferences, to avoid failure resulting from negotiating different
1279 * singleton values (which always leads to failure).
1280 * These settings can still (later) be overridden via sockopts.
1281 */
1282 if (ccid_get_builtin_ccids(&tx.val, &tx.len) ||
1283 ccid_get_builtin_ccids(&rx.val, &rx.len))
1284 return -ENOBUFS;
1285
Gerrit Renker883ca832009-01-16 23:36:32 +00001286 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
1287 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
Gerrit Renkerf90f92e2009-01-16 23:36:30 +00001288 goto free_ccid_lists;
1289
1290 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
1291 if (rc)
1292 goto free_ccid_lists;
1293
1294 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
1295
1296free_ccid_lists:
1297 kfree(tx.val);
1298 kfree(rx.val);
Andrea Bittauafe00252006-03-20 17:43:56 -08001299 return rc;
1300}
1301
Gerrit Renker422d9cd2008-12-01 23:34:01 -08001302int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1303{
1304 struct dccp_sock *dp = dccp_sk(sk);
1305 struct dccp_feat_entry *cur, *next;
1306 int idx;
1307 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1308 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1309 };
1310
1311 list_for_each_entry(cur, fn_list, node) {
1312 /*
1313 * An empty Confirm means that either an unknown feature type
1314 * or an invalid value was present. In the first case there is
1315 * nothing to activate, in the other the default value is used.
1316 */
1317 if (cur->empty_confirm)
1318 continue;
1319
1320 idx = dccp_feat_index(cur->feat_num);
1321 if (idx < 0) {
1322 DCCP_BUG("Unknown feature %u", cur->feat_num);
1323 goto activation_failed;
1324 }
1325 if (cur->state != FEAT_STABLE) {
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001326 DCCP_CRIT("Negotiation of %s %s failed in state %s",
Gerrit Renker422d9cd2008-12-01 23:34:01 -08001327 cur->is_local ? "local" : "remote",
Gerrit Renkerf3f3abb2009-01-16 23:36:33 +00001328 dccp_feat_fname(cur->feat_num),
1329 dccp_feat_sname[cur->state]);
Gerrit Renker422d9cd2008-12-01 23:34:01 -08001330 goto activation_failed;
1331 }
1332 fvals[idx][cur->is_local] = &cur->val;
1333 }
1334
1335 /*
1336 * Activate in decreasing order of index, so that the CCIDs are always
1337 * activated as the last feature. This avoids the case where a CCID
1338 * relies on the initialisation of one or more features that it depends
1339 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1340 */
1341 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1342 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1343 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1344 DCCP_CRIT("Could not activate %d", idx);
1345 goto activation_failed;
1346 }
1347
1348 /* Clean up Change options which have been confirmed already */
1349 list_for_each_entry_safe(cur, next, fn_list, node)
1350 if (!cur->needs_confirm)
1351 dccp_feat_list_pop(cur);
1352
1353 dccp_pr_debug("Activation OK\n");
1354 return 0;
1355
1356activation_failed:
1357 /*
1358 * We clean up everything that may have been allocated, since
1359 * it is difficult to track at which stage negotiation failed.
1360 * This is ok, since all allocation functions below are robust
1361 * against NULL arguments.
1362 */
1363 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1364 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1365 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1366 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1367 dp->dccps_hc_rx_ackvec = NULL;
1368 return -1;
1369}