Root/
1 | /* |
2 | * net/dccp/feat.c |
3 | * |
4 | * Feature negotiation for the DCCP protocol (RFC 4340, section 6) |
5 | * |
6 | * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk> |
7 | * Rewrote from scratch, some bits from earlier code by |
8 | * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk> |
9 | * |
10 | * |
11 | * ASSUMPTIONS |
12 | * ----------- |
13 | * o Feature negotiation is coordinated with connection setup (as in TCP), wild |
14 | * changes of parameters of an established connection are not supported. |
15 | * o Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN. |
16 | * o All currently known SP features have 1-byte quantities. If in the future |
17 | * extensions of RFCs 4340..42 define features with item lengths larger than |
18 | * one byte, a feature-specific extension of the code will be required. |
19 | * |
20 | * This program is free software; you can redistribute it and/or |
21 | * modify it under the terms of the GNU General Public License |
22 | * as published by the Free Software Foundation; either version |
23 | * 2 of the License, or (at your option) any later version. |
24 | */ |
25 | #include <linux/module.h> |
26 | #include <linux/slab.h> |
27 | #include "ccid.h" |
28 | #include "feat.h" |
29 | |
30 | /* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */ |
31 | unsigned long sysctl_dccp_sequence_window __read_mostly = 100; |
32 | int sysctl_dccp_rx_ccid __read_mostly = 2, |
33 | sysctl_dccp_tx_ccid __read_mostly = 2; |
34 | |
35 | /* |
36 | * Feature activation handlers. |
37 | * |
38 | * These all use an u64 argument, to provide enough room for NN/SP features. At |
39 | * this stage the negotiated values have been checked to be within their range. |
40 | */ |
41 | static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx) |
42 | { |
43 | struct dccp_sock *dp = dccp_sk(sk); |
44 | struct ccid *new_ccid = ccid_new(ccid, sk, rx); |
45 | |
46 | if (new_ccid == NULL) |
47 | return -ENOMEM; |
48 | |
49 | if (rx) { |
50 | ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); |
51 | dp->dccps_hc_rx_ccid = new_ccid; |
52 | } else { |
53 | ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); |
54 | dp->dccps_hc_tx_ccid = new_ccid; |
55 | } |
56 | return 0; |
57 | } |
58 | |
59 | static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx) |
60 | { |
61 | struct dccp_sock *dp = dccp_sk(sk); |
62 | |
63 | if (rx) { |
64 | dp->dccps_r_seq_win = seq_win; |
65 | /* propagate changes to update SWL/SWH */ |
66 | dccp_update_gsr(sk, dp->dccps_gsr); |
67 | } else { |
68 | dp->dccps_l_seq_win = seq_win; |
69 | /* propagate changes to update AWL */ |
70 | dccp_update_gss(sk, dp->dccps_gss); |
71 | } |
72 | return 0; |
73 | } |
74 | |
75 | static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx) |
76 | { |
77 | if (rx) |
78 | dccp_sk(sk)->dccps_r_ack_ratio = ratio; |
79 | else |
80 | dccp_sk(sk)->dccps_l_ack_ratio = ratio; |
81 | return 0; |
82 | } |
83 | |
84 | static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx) |
85 | { |
86 | struct dccp_sock *dp = dccp_sk(sk); |
87 | |
88 | if (rx) { |
89 | if (enable && dp->dccps_hc_rx_ackvec == NULL) { |
90 | dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any()); |
91 | if (dp->dccps_hc_rx_ackvec == NULL) |
92 | return -ENOMEM; |
93 | } else if (!enable) { |
94 | dccp_ackvec_free(dp->dccps_hc_rx_ackvec); |
95 | dp->dccps_hc_rx_ackvec = NULL; |
96 | } |
97 | } |
98 | return 0; |
99 | } |
100 | |
101 | static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx) |
102 | { |
103 | if (!rx) |
104 | dccp_sk(sk)->dccps_send_ndp_count = (enable > 0); |
105 | return 0; |
106 | } |
107 | |
108 | /* |
109 | * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that |
110 | * `rx' holds when the sending peer informs about his partial coverage via a |
111 | * ChangeR() option. In the other case, we are the sender and the receiver |
112 | * announces its coverage via ChangeL() options. The policy here is to honour |
113 | * such communication by enabling the corresponding partial coverage - but only |
114 | * if it has not been set manually before; the warning here means that all |
115 | * packets will be dropped. |
116 | */ |
117 | static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx) |
118 | { |
119 | struct dccp_sock *dp = dccp_sk(sk); |
120 | |
121 | if (rx) |
122 | dp->dccps_pcrlen = cscov; |
123 | else { |
124 | if (dp->dccps_pcslen == 0) |
125 | dp->dccps_pcslen = cscov; |
126 | else if (cscov > dp->dccps_pcslen) |
127 | DCCP_WARN("CsCov %u too small, peer requires >= %u\n", |
128 | dp->dccps_pcslen, (u8)cscov); |
129 | } |
130 | return 0; |
131 | } |
132 | |
133 | static const struct { |
134 | u8 feat_num; /* DCCPF_xxx */ |
135 | enum dccp_feat_type rxtx; /* RX or TX */ |
136 | enum dccp_feat_type reconciliation; /* SP or NN */ |
137 | u8 default_value; /* as in 6.4 */ |
138 | int (*activation_hdlr)(struct sock *sk, u64 val, bool rx); |
139 | /* |
140 | * Lookup table for location and type of features (from RFC 4340/4342) |
141 | * +--------------------------+----+-----+----+----+---------+-----------+ |
142 | * | Feature | Location | Reconc. | Initial | Section | |
143 | * | | RX | TX | SP | NN | Value | Reference | |
144 | * +--------------------------+----+-----+----+----+---------+-----------+ |
145 | * | DCCPF_CCID | | X | X | | 2 | 10 | |
146 | * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 | |
147 | * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 | |
148 | * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 | |
149 | * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 | |
150 | * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 | |
151 | * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 | |
152 | * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 | |
153 | * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 | |
154 | * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 | |
155 | * +--------------------------+----+-----+----+----+---------+-----------+ |
156 | */ |
157 | } dccp_feat_table[] = { |
158 | { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid }, |
159 | { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL }, |
160 | { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win }, |
161 | { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL }, |
162 | { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio}, |
163 | { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec }, |
164 | { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp }, |
165 | { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov}, |
166 | { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL }, |
167 | { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL }, |
168 | }; |
169 | #define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table) |
170 | |
171 | /** |
172 | * dccp_feat_index - Hash function to map feature number into array position |
173 | * Returns consecutive array index or -1 if the feature is not understood. |
174 | */ |
175 | static int dccp_feat_index(u8 feat_num) |
176 | { |
177 | /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */ |
178 | if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM) |
179 | return feat_num - 1; |
180 | |
181 | /* |
182 | * Other features: add cases for new feature types here after adding |
183 | * them to the above table. |
184 | */ |
185 | switch (feat_num) { |
186 | case DCCPF_SEND_LEV_RATE: |
187 | return DCCP_FEAT_SUPPORTED_MAX - 1; |
188 | } |
189 | return -1; |
190 | } |
191 | |
192 | static u8 dccp_feat_type(u8 feat_num) |
193 | { |
194 | int idx = dccp_feat_index(feat_num); |
195 | |
196 | if (idx < 0) |
197 | return FEAT_UNKNOWN; |
198 | return dccp_feat_table[idx].reconciliation; |
199 | } |
200 | |
201 | static int dccp_feat_default_value(u8 feat_num) |
202 | { |
203 | int idx = dccp_feat_index(feat_num); |
204 | /* |
205 | * There are no default values for unknown features, so encountering a |
206 | * negative index here indicates a serious problem somewhere else. |
207 | */ |
208 | DCCP_BUG_ON(idx < 0); |
209 | |
210 | return idx < 0 ? 0 : dccp_feat_table[idx].default_value; |
211 | } |
212 | |
213 | /* |
214 | * Debugging and verbose-printing section |
215 | */ |
216 | static const char *dccp_feat_fname(const u8 feat) |
217 | { |
218 | static const char *const feature_names[] = { |
219 | [DCCPF_RESERVED] = "Reserved", |
220 | [DCCPF_CCID] = "CCID", |
221 | [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos", |
222 | [DCCPF_SEQUENCE_WINDOW] = "Sequence Window", |
223 | [DCCPF_ECN_INCAPABLE] = "ECN Incapable", |
224 | [DCCPF_ACK_RATIO] = "Ack Ratio", |
225 | [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector", |
226 | [DCCPF_SEND_NDP_COUNT] = "Send NDP Count", |
227 | [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage", |
228 | [DCCPF_DATA_CHECKSUM] = "Send Data Checksum", |
229 | }; |
230 | if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC) |
231 | return feature_names[DCCPF_RESERVED]; |
232 | |
233 | if (feat == DCCPF_SEND_LEV_RATE) |
234 | return "Send Loss Event Rate"; |
235 | if (feat >= DCCPF_MIN_CCID_SPECIFIC) |
236 | return "CCID-specific"; |
237 | |
238 | return feature_names[feat]; |
239 | } |
240 | |
241 | static const char *const dccp_feat_sname[] = { |
242 | "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE", |
243 | }; |
244 | |
245 | #ifdef CONFIG_IP_DCCP_DEBUG |
246 | static const char *dccp_feat_oname(const u8 opt) |
247 | { |
248 | switch (opt) { |
249 | case DCCPO_CHANGE_L: return "Change_L"; |
250 | case DCCPO_CONFIRM_L: return "Confirm_L"; |
251 | case DCCPO_CHANGE_R: return "Change_R"; |
252 | case DCCPO_CONFIRM_R: return "Confirm_R"; |
253 | } |
254 | return NULL; |
255 | } |
256 | |
257 | static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val) |
258 | { |
259 | u8 i, type = dccp_feat_type(feat_num); |
260 | |
261 | if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL)) |
262 | dccp_pr_debug_cat("(NULL)"); |
263 | else if (type == FEAT_SP) |
264 | for (i = 0; i < val->sp.len; i++) |
265 | dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]); |
266 | else if (type == FEAT_NN) |
267 | dccp_pr_debug_cat("%llu", (unsigned long long)val->nn); |
268 | else |
269 | dccp_pr_debug_cat("unknown type %u", type); |
270 | } |
271 | |
272 | static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len) |
273 | { |
274 | u8 type = dccp_feat_type(feat_num); |
275 | dccp_feat_val fval = { .sp.vec = list, .sp.len = len }; |
276 | |
277 | if (type == FEAT_NN) |
278 | fval.nn = dccp_decode_value_var(list, len); |
279 | dccp_feat_printval(feat_num, &fval); |
280 | } |
281 | |
282 | static void dccp_feat_print_entry(struct dccp_feat_entry const *entry) |
283 | { |
284 | dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote", |
285 | dccp_feat_fname(entry->feat_num)); |
286 | dccp_feat_printval(entry->feat_num, &entry->val); |
287 | dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state], |
288 | entry->needs_confirm ? "(Confirm pending)" : ""); |
289 | } |
290 | |
291 | #define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \ |
292 | dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\ |
293 | dccp_feat_printvals(feat, val, len); \ |
294 | dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0) |
295 | |
296 | #define dccp_feat_print_fnlist(fn_list) { \ |
297 | const struct dccp_feat_entry *___entry; \ |
298 | \ |
299 | dccp_pr_debug("List Dump:\n"); \ |
300 | list_for_each_entry(___entry, fn_list, node) \ |
301 | dccp_feat_print_entry(___entry); \ |
302 | } |
303 | #else /* ! CONFIG_IP_DCCP_DEBUG */ |
304 | #define dccp_feat_print_opt(opt, feat, val, len, mandatory) |
305 | #define dccp_feat_print_fnlist(fn_list) |
306 | #endif |
307 | |
308 | static int __dccp_feat_activate(struct sock *sk, const int idx, |
309 | const bool is_local, dccp_feat_val const *fval) |
310 | { |
311 | bool rx; |
312 | u64 val; |
313 | |
314 | if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX) |
315 | return -1; |
316 | if (dccp_feat_table[idx].activation_hdlr == NULL) |
317 | return 0; |
318 | |
319 | if (fval == NULL) { |
320 | val = dccp_feat_table[idx].default_value; |
321 | } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) { |
322 | if (fval->sp.vec == NULL) { |
323 | /* |
324 | * This can happen when an empty Confirm is sent |
325 | * for an SP (i.e. known) feature. In this case |
326 | * we would be using the default anyway. |
327 | */ |
328 | DCCP_CRIT("Feature #%d undefined: using default", idx); |
329 | val = dccp_feat_table[idx].default_value; |
330 | } else { |
331 | val = fval->sp.vec[0]; |
332 | } |
333 | } else { |
334 | val = fval->nn; |
335 | } |
336 | |
337 | /* Location is RX if this is a local-RX or remote-TX feature */ |
338 | rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX)); |
339 | |
340 | dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX", |
341 | dccp_feat_fname(dccp_feat_table[idx].feat_num), |
342 | fval ? "" : "default ", (unsigned long long)val); |
343 | |
344 | return dccp_feat_table[idx].activation_hdlr(sk, val, rx); |
345 | } |
346 | |
347 | /** |
348 | * dccp_feat_activate - Activate feature value on socket |
349 | * @sk: fully connected DCCP socket (after handshake is complete) |
350 | * @feat_num: feature to activate, one of %dccp_feature_numbers |
351 | * @local: whether local (1) or remote (0) @feat_num is meant |
352 | * @fval: the value (SP or NN) to activate, or NULL to use the default value |
353 | * |
354 | * For general use this function is preferable over __dccp_feat_activate(). |
355 | */ |
356 | static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local, |
357 | dccp_feat_val const *fval) |
358 | { |
359 | return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval); |
360 | } |
361 | |
362 | /* Test for "Req'd" feature (RFC 4340, 6.4) */ |
363 | static inline int dccp_feat_must_be_understood(u8 feat_num) |
364 | { |
365 | return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS || |
366 | feat_num == DCCPF_SEQUENCE_WINDOW; |
367 | } |
368 | |
369 | /* copy constructor, fval must not already contain allocated memory */ |
370 | static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len) |
371 | { |
372 | fval->sp.len = len; |
373 | if (fval->sp.len > 0) { |
374 | fval->sp.vec = kmemdup(val, len, gfp_any()); |
375 | if (fval->sp.vec == NULL) { |
376 | fval->sp.len = 0; |
377 | return -ENOBUFS; |
378 | } |
379 | } |
380 | return 0; |
381 | } |
382 | |
383 | static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val) |
384 | { |
385 | if (unlikely(val == NULL)) |
386 | return; |
387 | if (dccp_feat_type(feat_num) == FEAT_SP) |
388 | kfree(val->sp.vec); |
389 | memset(val, 0, sizeof(*val)); |
390 | } |
391 | |
392 | static struct dccp_feat_entry * |
393 | dccp_feat_clone_entry(struct dccp_feat_entry const *original) |
394 | { |
395 | struct dccp_feat_entry *new; |
396 | u8 type = dccp_feat_type(original->feat_num); |
397 | |
398 | if (type == FEAT_UNKNOWN) |
399 | return NULL; |
400 | |
401 | new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any()); |
402 | if (new == NULL) |
403 | return NULL; |
404 | |
405 | if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val, |
406 | original->val.sp.vec, |
407 | original->val.sp.len)) { |
408 | kfree(new); |
409 | return NULL; |
410 | } |
411 | return new; |
412 | } |
413 | |
414 | static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry) |
415 | { |
416 | if (entry != NULL) { |
417 | dccp_feat_val_destructor(entry->feat_num, &entry->val); |
418 | kfree(entry); |
419 | } |
420 | } |
421 | |
422 | /* |
423 | * List management functions |
424 | * |
425 | * Feature negotiation lists rely on and maintain the following invariants: |
426 | * - each feat_num in the list is known, i.e. we know its type and default value |
427 | * - each feat_num/is_local combination is unique (old entries are overwritten) |
428 | * - SP values are always freshly allocated |
429 | * - list is sorted in increasing order of feature number (faster lookup) |
430 | */ |
431 | static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list, |
432 | u8 feat_num, bool is_local) |
433 | { |
434 | struct dccp_feat_entry *entry; |
435 | |
436 | list_for_each_entry(entry, fn_list, node) { |
437 | if (entry->feat_num == feat_num && entry->is_local == is_local) |
438 | return entry; |
439 | else if (entry->feat_num > feat_num) |
440 | break; |
441 | } |
442 | return NULL; |
443 | } |
444 | |
445 | /** |
446 | * dccp_feat_entry_new - Central list update routine (called by all others) |
447 | * @head: list to add to |
448 | * @feat: feature number |
449 | * @local: whether the local (1) or remote feature with number @feat is meant |
450 | * |
451 | * This is the only constructor and serves to ensure the above invariants. |
452 | */ |
453 | static struct dccp_feat_entry * |
454 | dccp_feat_entry_new(struct list_head *head, u8 feat, bool local) |
455 | { |
456 | struct dccp_feat_entry *entry; |
457 | |
458 | list_for_each_entry(entry, head, node) |
459 | if (entry->feat_num == feat && entry->is_local == local) { |
460 | dccp_feat_val_destructor(entry->feat_num, &entry->val); |
461 | return entry; |
462 | } else if (entry->feat_num > feat) { |
463 | head = &entry->node; |
464 | break; |
465 | } |
466 | |
467 | entry = kmalloc(sizeof(*entry), gfp_any()); |
468 | if (entry != NULL) { |
469 | entry->feat_num = feat; |
470 | entry->is_local = local; |
471 | list_add_tail(&entry->node, head); |
472 | } |
473 | return entry; |
474 | } |
475 | |
476 | /** |
477 | * dccp_feat_push_change - Add/overwrite a Change option in the list |
478 | * @fn_list: feature-negotiation list to update |
479 | * @feat: one of %dccp_feature_numbers |
480 | * @local: whether local (1) or remote (0) @feat_num is meant |
481 | * @needs_mandatory: whether to use Mandatory feature negotiation options |
482 | * @fval: pointer to NN/SP value to be inserted (will be copied) |
483 | */ |
484 | static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local, |
485 | u8 mandatory, dccp_feat_val *fval) |
486 | { |
487 | struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); |
488 | |
489 | if (new == NULL) |
490 | return -ENOMEM; |
491 | |
492 | new->feat_num = feat; |
493 | new->is_local = local; |
494 | new->state = FEAT_INITIALISING; |
495 | new->needs_confirm = false; |
496 | new->empty_confirm = false; |
497 | new->val = *fval; |
498 | new->needs_mandatory = mandatory; |
499 | |
500 | return 0; |
501 | } |
502 | |
503 | /** |
504 | * dccp_feat_push_confirm - Add a Confirm entry to the FN list |
505 | * @fn_list: feature-negotiation list to add to |
506 | * @feat: one of %dccp_feature_numbers |
507 | * @local: whether local (1) or remote (0) @feat_num is being confirmed |
508 | * @fval: pointer to NN/SP value to be inserted or NULL |
509 | * |
510 | * Returns 0 on success, a Reset code for further processing otherwise. |
511 | */ |
512 | static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local, |
513 | dccp_feat_val *fval) |
514 | { |
515 | struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); |
516 | |
517 | if (new == NULL) |
518 | return DCCP_RESET_CODE_TOO_BUSY; |
519 | |
520 | new->feat_num = feat; |
521 | new->is_local = local; |
522 | new->state = FEAT_STABLE; /* transition in 6.6.2 */ |
523 | new->needs_confirm = true; |
524 | new->empty_confirm = (fval == NULL); |
525 | new->val.nn = 0; /* zeroes the whole structure */ |
526 | if (!new->empty_confirm) |
527 | new->val = *fval; |
528 | new->needs_mandatory = false; |
529 | |
530 | return 0; |
531 | } |
532 | |
533 | static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local) |
534 | { |
535 | return dccp_feat_push_confirm(fn_list, feat, local, NULL); |
536 | } |
537 | |
538 | static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry) |
539 | { |
540 | list_del(&entry->node); |
541 | dccp_feat_entry_destructor(entry); |
542 | } |
543 | |
544 | void dccp_feat_list_purge(struct list_head *fn_list) |
545 | { |
546 | struct dccp_feat_entry *entry, *next; |
547 | |
548 | list_for_each_entry_safe(entry, next, fn_list, node) |
549 | dccp_feat_entry_destructor(entry); |
550 | INIT_LIST_HEAD(fn_list); |
551 | } |
552 | EXPORT_SYMBOL_GPL(dccp_feat_list_purge); |
553 | |
554 | /* generate @to as full clone of @from - @to must not contain any nodes */ |
555 | int dccp_feat_clone_list(struct list_head const *from, struct list_head *to) |
556 | { |
557 | struct dccp_feat_entry *entry, *new; |
558 | |
559 | INIT_LIST_HEAD(to); |
560 | list_for_each_entry(entry, from, node) { |
561 | new = dccp_feat_clone_entry(entry); |
562 | if (new == NULL) |
563 | goto cloning_failed; |
564 | list_add_tail(&new->node, to); |
565 | } |
566 | return 0; |
567 | |
568 | cloning_failed: |
569 | dccp_feat_list_purge(to); |
570 | return -ENOMEM; |
571 | } |
572 | |
573 | /** |
574 | * dccp_feat_valid_nn_length - Enforce length constraints on NN options |
575 | * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only, |
576 | * incoming options are accepted as long as their values are valid. |
577 | */ |
578 | static u8 dccp_feat_valid_nn_length(u8 feat_num) |
579 | { |
580 | if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */ |
581 | return 2; |
582 | if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */ |
583 | return 6; |
584 | return 0; |
585 | } |
586 | |
587 | static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val) |
588 | { |
589 | switch (feat_num) { |
590 | case DCCPF_ACK_RATIO: |
591 | return val <= DCCPF_ACK_RATIO_MAX; |
592 | case DCCPF_SEQUENCE_WINDOW: |
593 | return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX; |
594 | } |
595 | return 0; /* feature unknown - so we can't tell */ |
596 | } |
597 | |
598 | /* check that SP values are within the ranges defined in RFC 4340 */ |
599 | static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val) |
600 | { |
601 | switch (feat_num) { |
602 | case DCCPF_CCID: |
603 | return val == DCCPC_CCID2 || val == DCCPC_CCID3; |
604 | /* Type-check Boolean feature values: */ |
605 | case DCCPF_SHORT_SEQNOS: |
606 | case DCCPF_ECN_INCAPABLE: |
607 | case DCCPF_SEND_ACK_VECTOR: |
608 | case DCCPF_SEND_NDP_COUNT: |
609 | case DCCPF_DATA_CHECKSUM: |
610 | case DCCPF_SEND_LEV_RATE: |
611 | return val < 2; |
612 | case DCCPF_MIN_CSUM_COVER: |
613 | return val < 16; |
614 | } |
615 | return 0; /* feature unknown */ |
616 | } |
617 | |
618 | static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len) |
619 | { |
620 | if (sp_list == NULL || sp_len < 1) |
621 | return 0; |
622 | while (sp_len--) |
623 | if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++)) |
624 | return 0; |
625 | return 1; |
626 | } |
627 | |
628 | /** |
629 | * dccp_feat_insert_opts - Generate FN options from current list state |
630 | * @skb: next sk_buff to be sent to the peer |
631 | * @dp: for client during handshake and general negotiation |
632 | * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND) |
633 | */ |
634 | int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq, |
635 | struct sk_buff *skb) |
636 | { |
637 | struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; |
638 | struct dccp_feat_entry *pos, *next; |
639 | u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN]; |
640 | bool rpt; |
641 | |
642 | /* put entries into @skb in the order they appear in the list */ |
643 | list_for_each_entry_safe_reverse(pos, next, fn, node) { |
644 | opt = dccp_feat_genopt(pos); |
645 | type = dccp_feat_type(pos->feat_num); |
646 | rpt = false; |
647 | |
648 | if (pos->empty_confirm) { |
649 | len = 0; |
650 | ptr = NULL; |
651 | } else { |
652 | if (type == FEAT_SP) { |
653 | len = pos->val.sp.len; |
654 | ptr = pos->val.sp.vec; |
655 | rpt = pos->needs_confirm; |
656 | } else if (type == FEAT_NN) { |
657 | len = dccp_feat_valid_nn_length(pos->feat_num); |
658 | ptr = nn_in_nbo; |
659 | dccp_encode_value_var(pos->val.nn, ptr, len); |
660 | } else { |
661 | DCCP_BUG("unknown feature %u", pos->feat_num); |
662 | return -1; |
663 | } |
664 | } |
665 | dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0); |
666 | |
667 | if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt)) |
668 | return -1; |
669 | if (pos->needs_mandatory && dccp_insert_option_mandatory(skb)) |
670 | return -1; |
671 | |
672 | if (skb->sk->sk_state == DCCP_OPEN && |
673 | (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) { |
674 | /* |
675 | * Confirms don't get retransmitted (6.6.3) once the |
676 | * connection is in state OPEN |
677 | */ |
678 | dccp_feat_list_pop(pos); |
679 | } else { |
680 | /* |
681 | * Enter CHANGING after transmitting the Change |
682 | * option (6.6.2). |
683 | */ |
684 | if (pos->state == FEAT_INITIALISING) |
685 | pos->state = FEAT_CHANGING; |
686 | } |
687 | } |
688 | return 0; |
689 | } |
690 | |
691 | /** |
692 | * __feat_register_nn - Register new NN value on socket |
693 | * @fn: feature-negotiation list to register with |
694 | * @feat: an NN feature from %dccp_feature_numbers |
695 | * @mandatory: use Mandatory option if 1 |
696 | * @nn_val: value to register (restricted to 4 bytes) |
697 | * |
698 | * Note that NN features are local by definition (RFC 4340, 6.3.2). |
699 | */ |
700 | static int __feat_register_nn(struct list_head *fn, u8 feat, |
701 | u8 mandatory, u64 nn_val) |
702 | { |
703 | dccp_feat_val fval = { .nn = nn_val }; |
704 | |
705 | if (dccp_feat_type(feat) != FEAT_NN || |
706 | !dccp_feat_is_valid_nn_val(feat, nn_val)) |
707 | return -EINVAL; |
708 | |
709 | /* Don't bother with default values, they will be activated anyway. */ |
710 | if (nn_val - (u64)dccp_feat_default_value(feat) == 0) |
711 | return 0; |
712 | |
713 | return dccp_feat_push_change(fn, feat, 1, mandatory, &fval); |
714 | } |
715 | |
716 | /** |
717 | * __feat_register_sp - Register new SP value/list on socket |
718 | * @fn: feature-negotiation list to register with |
719 | * @feat: an SP feature from %dccp_feature_numbers |
720 | * @is_local: whether the local (1) or the remote (0) @feat is meant |
721 | * @mandatory: use Mandatory option if 1 |
722 | * @sp_val: SP value followed by optional preference list |
723 | * @sp_len: length of @sp_val in bytes |
724 | */ |
725 | static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local, |
726 | u8 mandatory, u8 const *sp_val, u8 sp_len) |
727 | { |
728 | dccp_feat_val fval; |
729 | |
730 | if (dccp_feat_type(feat) != FEAT_SP || |
731 | !dccp_feat_sp_list_ok(feat, sp_val, sp_len)) |
732 | return -EINVAL; |
733 | |
734 | /* Avoid negotiating alien CCIDs by only advertising supported ones */ |
735 | if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len)) |
736 | return -EOPNOTSUPP; |
737 | |
738 | if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len)) |
739 | return -ENOMEM; |
740 | |
741 | return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval); |
742 | } |
743 | |
744 | /** |
745 | * dccp_feat_register_sp - Register requests to change SP feature values |
746 | * @sk: client or listening socket |
747 | * @feat: one of %dccp_feature_numbers |
748 | * @is_local: whether the local (1) or remote (0) @feat is meant |
749 | * @list: array of preferred values, in descending order of preference |
750 | * @len: length of @list in bytes |
751 | */ |
752 | int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local, |
753 | u8 const *list, u8 len) |
754 | { /* any changes must be registered before establishing the connection */ |
755 | if (sk->sk_state != DCCP_CLOSED) |
756 | return -EISCONN; |
757 | if (dccp_feat_type(feat) != FEAT_SP) |
758 | return -EINVAL; |
759 | return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local, |
760 | 0, list, len); |
761 | } |
762 | |
763 | /** |
764 | * dccp_feat_nn_get - Query current/pending value of NN feature |
765 | * @sk: DCCP socket of an established connection |
766 | * @feat: NN feature number from %dccp_feature_numbers |
767 | * |
768 | * For a known NN feature, returns value currently being negotiated, or |
769 | * current (confirmed) value if no negotiation is going on. |
770 | */ |
771 | u64 dccp_feat_nn_get(struct sock *sk, u8 feat) |
772 | { |
773 | if (dccp_feat_type(feat) == FEAT_NN) { |
774 | struct dccp_sock *dp = dccp_sk(sk); |
775 | struct dccp_feat_entry *entry; |
776 | |
777 | entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1); |
778 | if (entry != NULL) |
779 | return entry->val.nn; |
780 | |
781 | switch (feat) { |
782 | case DCCPF_ACK_RATIO: |
783 | return dp->dccps_l_ack_ratio; |
784 | case DCCPF_SEQUENCE_WINDOW: |
785 | return dp->dccps_l_seq_win; |
786 | } |
787 | } |
788 | DCCP_BUG("attempt to look up unsupported feature %u", feat); |
789 | return 0; |
790 | } |
791 | EXPORT_SYMBOL_GPL(dccp_feat_nn_get); |
792 | |
793 | /** |
794 | * dccp_feat_signal_nn_change - Update NN values for an established connection |
795 | * @sk: DCCP socket of an established connection |
796 | * @feat: NN feature number from %dccp_feature_numbers |
797 | * @nn_val: the new value to use |
798 | * |
799 | * This function is used to communicate NN updates out-of-band. |
800 | */ |
801 | int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val) |
802 | { |
803 | struct list_head *fn = &dccp_sk(sk)->dccps_featneg; |
804 | dccp_feat_val fval = { .nn = nn_val }; |
805 | struct dccp_feat_entry *entry; |
806 | |
807 | if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN) |
808 | return 0; |
809 | |
810 | if (dccp_feat_type(feat) != FEAT_NN || |
811 | !dccp_feat_is_valid_nn_val(feat, nn_val)) |
812 | return -EINVAL; |
813 | |
814 | if (nn_val == dccp_feat_nn_get(sk, feat)) |
815 | return 0; /* already set or negotiation under way */ |
816 | |
817 | entry = dccp_feat_list_lookup(fn, feat, 1); |
818 | if (entry != NULL) { |
819 | dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n", |
820 | (unsigned long long)entry->val.nn, |
821 | (unsigned long long)nn_val); |
822 | dccp_feat_list_pop(entry); |
823 | } |
824 | |
825 | inet_csk_schedule_ack(sk); |
826 | return dccp_feat_push_change(fn, feat, 1, 0, &fval); |
827 | } |
828 | EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change); |
829 | |
830 | /* |
831 | * Tracking features whose value depend on the choice of CCID |
832 | * |
833 | * This is designed with an extension in mind so that a list walk could be done |
834 | * before activating any features. However, the existing framework was found to |
835 | * work satisfactorily up until now, the automatic verification is left open. |
836 | * When adding new CCIDs, add a corresponding dependency table here. |
837 | */ |
838 | static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local) |
839 | { |
840 | static const struct ccid_dependency ccid2_dependencies[2][2] = { |
841 | /* |
842 | * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX |
843 | * feature and Send Ack Vector is an RX feature, `is_local' |
844 | * needs to be reversed. |
845 | */ |
846 | { /* Dependencies of the receiver-side (remote) CCID2 */ |
847 | { |
848 | .dependent_feat = DCCPF_SEND_ACK_VECTOR, |
849 | .is_local = true, |
850 | .is_mandatory = true, |
851 | .val = 1 |
852 | }, |
853 | { 0, 0, 0, 0 } |
854 | }, |
855 | { /* Dependencies of the sender-side (local) CCID2 */ |
856 | { |
857 | .dependent_feat = DCCPF_SEND_ACK_VECTOR, |
858 | .is_local = false, |
859 | .is_mandatory = true, |
860 | .val = 1 |
861 | }, |
862 | { 0, 0, 0, 0 } |
863 | } |
864 | }; |
865 | static const struct ccid_dependency ccid3_dependencies[2][5] = { |
866 | { /* |
867 | * Dependencies of the receiver-side CCID3 |
868 | */ |
869 | { /* locally disable Ack Vectors */ |
870 | .dependent_feat = DCCPF_SEND_ACK_VECTOR, |
871 | .is_local = true, |
872 | .is_mandatory = false, |
873 | .val = 0 |
874 | }, |
875 | { /* see below why Send Loss Event Rate is on */ |
876 | .dependent_feat = DCCPF_SEND_LEV_RATE, |
877 | .is_local = true, |
878 | .is_mandatory = true, |
879 | .val = 1 |
880 | }, |
881 | { /* NDP Count is needed as per RFC 4342, 6.1.1 */ |
882 | .dependent_feat = DCCPF_SEND_NDP_COUNT, |
883 | .is_local = false, |
884 | .is_mandatory = true, |
885 | .val = 1 |
886 | }, |
887 | { 0, 0, 0, 0 }, |
888 | }, |
889 | { /* |
890 | * CCID3 at the TX side: we request that the HC-receiver |
891 | * will not send Ack Vectors (they will be ignored, so |
892 | * Mandatory is not set); we enable Send Loss Event Rate |
893 | * (Mandatory since the implementation does not support |
894 | * the Loss Intervals option of RFC 4342, 8.6). |
895 | * The last two options are for peer's information only. |
896 | */ |
897 | { |
898 | .dependent_feat = DCCPF_SEND_ACK_VECTOR, |
899 | .is_local = false, |
900 | .is_mandatory = false, |
901 | .val = 0 |
902 | }, |
903 | { |
904 | .dependent_feat = DCCPF_SEND_LEV_RATE, |
905 | .is_local = false, |
906 | .is_mandatory = true, |
907 | .val = 1 |
908 | }, |
909 | { /* this CCID does not support Ack Ratio */ |
910 | .dependent_feat = DCCPF_ACK_RATIO, |
911 | .is_local = true, |
912 | .is_mandatory = false, |
913 | .val = 0 |
914 | }, |
915 | { /* tell receiver we are sending NDP counts */ |
916 | .dependent_feat = DCCPF_SEND_NDP_COUNT, |
917 | .is_local = true, |
918 | .is_mandatory = false, |
919 | .val = 1 |
920 | }, |
921 | { 0, 0, 0, 0 } |
922 | } |
923 | }; |
924 | switch (ccid) { |
925 | case DCCPC_CCID2: |
926 | return ccid2_dependencies[is_local]; |
927 | case DCCPC_CCID3: |
928 | return ccid3_dependencies[is_local]; |
929 | default: |
930 | return NULL; |
931 | } |
932 | } |
933 | |
934 | /** |
935 | * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID |
936 | * @fn: feature-negotiation list to update |
937 | * @id: CCID number to track |
938 | * @is_local: whether TX CCID (1) or RX CCID (0) is meant |
939 | * |
940 | * This function needs to be called after registering all other features. |
941 | */ |
942 | static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local) |
943 | { |
944 | const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local); |
945 | int i, rc = (table == NULL); |
946 | |
947 | for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++) |
948 | if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP) |
949 | rc = __feat_register_sp(fn, table[i].dependent_feat, |
950 | table[i].is_local, |
951 | table[i].is_mandatory, |
952 | &table[i].val, 1); |
953 | else |
954 | rc = __feat_register_nn(fn, table[i].dependent_feat, |
955 | table[i].is_mandatory, |
956 | table[i].val); |
957 | return rc; |
958 | } |
959 | |
960 | /** |
961 | * dccp_feat_finalise_settings - Finalise settings before starting negotiation |
962 | * @dp: client or listening socket (settings will be inherited) |
963 | * |
964 | * This is called after all registrations (socket initialisation, sysctls, and |
965 | * sockopt calls), and before sending the first packet containing Change options |
966 | * (ie. client-Request or server-Response), to ensure internal consistency. |
967 | */ |
968 | int dccp_feat_finalise_settings(struct dccp_sock *dp) |
969 | { |
970 | struct list_head *fn = &dp->dccps_featneg; |
971 | struct dccp_feat_entry *entry; |
972 | int i = 2, ccids[2] = { -1, -1 }; |
973 | |
974 | /* |
975 | * Propagating CCIDs: |
976 | * 1) not useful to propagate CCID settings if this host advertises more |
977 | * than one CCID: the choice of CCID may still change - if this is |
978 | * the client, or if this is the server and the client sends |
979 | * singleton CCID values. |
980 | * 2) since is that propagate_ccid changes the list, we defer changing |
981 | * the sorted list until after the traversal. |
982 | */ |
983 | list_for_each_entry(entry, fn, node) |
984 | if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1) |
985 | ccids[entry->is_local] = entry->val.sp.vec[0]; |
986 | while (i--) |
987 | if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i)) |
988 | return -1; |
989 | dccp_feat_print_fnlist(fn); |
990 | return 0; |
991 | } |
992 | |
993 | /** |
994 | * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features |
995 | * It is the server which resolves the dependencies once the CCID has been |
996 | * fully negotiated. If no CCID has been negotiated, it uses the default CCID. |
997 | */ |
998 | int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq) |
999 | { |
1000 | struct list_head *fn = &dreq->dreq_featneg; |
1001 | struct dccp_feat_entry *entry; |
1002 | u8 is_local, ccid; |
1003 | |
1004 | for (is_local = 0; is_local <= 1; is_local++) { |
1005 | entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local); |
1006 | |
1007 | if (entry != NULL && !entry->empty_confirm) |
1008 | ccid = entry->val.sp.vec[0]; |
1009 | else |
1010 | ccid = dccp_feat_default_value(DCCPF_CCID); |
1011 | |
1012 | if (dccp_feat_propagate_ccid(fn, ccid, is_local)) |
1013 | return -1; |
1014 | } |
1015 | return 0; |
1016 | } |
1017 | |
1018 | /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */ |
1019 | static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen) |
1020 | { |
1021 | u8 c, s; |
1022 | |
1023 | for (s = 0; s < slen; s++) |
1024 | for (c = 0; c < clen; c++) |
1025 | if (servlist[s] == clilist[c]) |
1026 | return servlist[s]; |
1027 | return -1; |
1028 | } |
1029 | |
1030 | /** |
1031 | * dccp_feat_prefer - Move preferred entry to the start of array |
1032 | * Reorder the @array_len elements in @array so that @preferred_value comes |
1033 | * first. Returns >0 to indicate that @preferred_value does occur in @array. |
1034 | */ |
1035 | static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len) |
1036 | { |
1037 | u8 i, does_occur = 0; |
1038 | |
1039 | if (array != NULL) { |
1040 | for (i = 0; i < array_len; i++) |
1041 | if (array[i] == preferred_value) { |
1042 | array[i] = array[0]; |
1043 | does_occur++; |
1044 | } |
1045 | if (does_occur) |
1046 | array[0] = preferred_value; |
1047 | } |
1048 | return does_occur; |
1049 | } |
1050 | |
1051 | /** |
1052 | * dccp_feat_reconcile - Reconcile SP preference lists |
1053 | * @fval: SP list to reconcile into |
1054 | * @arr: received SP preference list |
1055 | * @len: length of @arr in bytes |
1056 | * @is_server: whether this side is the server (and @fv is the server's list) |
1057 | * @reorder: whether to reorder the list in @fv after reconciling with @arr |
1058 | * When successful, > 0 is returned and the reconciled list is in @fval. |
1059 | * A value of 0 means that negotiation failed (no shared entry). |
1060 | */ |
1061 | static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len, |
1062 | bool is_server, bool reorder) |
1063 | { |
1064 | int rc; |
1065 | |
1066 | if (!fv->sp.vec || !arr) { |
1067 | DCCP_CRIT("NULL feature value or array"); |
1068 | return 0; |
1069 | } |
1070 | |
1071 | if (is_server) |
1072 | rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len); |
1073 | else |
1074 | rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len); |
1075 | |
1076 | if (!reorder) |
1077 | return rc; |
1078 | if (rc < 0) |
1079 | return 0; |
1080 | |
1081 | /* |
1082 | * Reorder list: used for activating features and in dccp_insert_fn_opt. |
1083 | */ |
1084 | return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len); |
1085 | } |
1086 | |
1087 | /** |
1088 | * dccp_feat_change_recv - Process incoming ChangeL/R options |
1089 | * @fn: feature-negotiation list to update |
1090 | * @is_mandatory: whether the Change was preceded by a Mandatory option |
1091 | * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R |
1092 | * @feat: one of %dccp_feature_numbers |
1093 | * @val: NN value or SP value/preference list |
1094 | * @len: length of @val in bytes |
1095 | * @server: whether this node is the server (1) or the client (0) |
1096 | */ |
1097 | static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt, |
1098 | u8 feat, u8 *val, u8 len, const bool server) |
1099 | { |
1100 | u8 defval, type = dccp_feat_type(feat); |
1101 | const bool local = (opt == DCCPO_CHANGE_R); |
1102 | struct dccp_feat_entry *entry; |
1103 | dccp_feat_val fval; |
1104 | |
1105 | if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */ |
1106 | goto unknown_feature_or_value; |
1107 | |
1108 | dccp_feat_print_opt(opt, feat, val, len, is_mandatory); |
1109 | |
1110 | /* |
1111 | * Negotiation of NN features: Change R is invalid, so there is no |
1112 | * simultaneous negotiation; hence we do not look up in the list. |
1113 | */ |
1114 | if (type == FEAT_NN) { |
1115 | if (local || len > sizeof(fval.nn)) |
1116 | goto unknown_feature_or_value; |
1117 | |
1118 | /* 6.3.2: "The feature remote MUST accept any valid value..." */ |
1119 | fval.nn = dccp_decode_value_var(val, len); |
1120 | if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) |
1121 | goto unknown_feature_or_value; |
1122 | |
1123 | return dccp_feat_push_confirm(fn, feat, local, &fval); |
1124 | } |
1125 | |
1126 | /* |
1127 | * Unidirectional/simultaneous negotiation of SP features (6.3.1) |
1128 | */ |
1129 | entry = dccp_feat_list_lookup(fn, feat, local); |
1130 | if (entry == NULL) { |
1131 | /* |
1132 | * No particular preferences have been registered. We deal with |
1133 | * this situation by assuming that all valid values are equally |
1134 | * acceptable, and apply the following checks: |
1135 | * - if the peer's list is a singleton, we accept a valid value; |
1136 | * - if we are the server, we first try to see if the peer (the |
1137 | * client) advertises the default value. If yes, we use it, |
1138 | * otherwise we accept the preferred value; |
1139 | * - else if we are the client, we use the first list element. |
1140 | */ |
1141 | if (dccp_feat_clone_sp_val(&fval, val, 1)) |
1142 | return DCCP_RESET_CODE_TOO_BUSY; |
1143 | |
1144 | if (len > 1 && server) { |
1145 | defval = dccp_feat_default_value(feat); |
1146 | if (dccp_feat_preflist_match(&defval, 1, val, len) > -1) |
1147 | fval.sp.vec[0] = defval; |
1148 | } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) { |
1149 | kfree(fval.sp.vec); |
1150 | goto unknown_feature_or_value; |
1151 | } |
1152 | |
1153 | /* Treat unsupported CCIDs like invalid values */ |
1154 | if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) { |
1155 | kfree(fval.sp.vec); |
1156 | goto not_valid_or_not_known; |
1157 | } |
1158 | |
1159 | return dccp_feat_push_confirm(fn, feat, local, &fval); |
1160 | |
1161 | } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */ |
1162 | return 0; |
1163 | } |
1164 | |
1165 | if (dccp_feat_reconcile(&entry->val, val, len, server, true)) { |
1166 | entry->empty_confirm = false; |
1167 | } else if (is_mandatory) { |
1168 | return DCCP_RESET_CODE_MANDATORY_ERROR; |
1169 | } else if (entry->state == FEAT_INITIALISING) { |
1170 | /* |
1171 | * Failed simultaneous negotiation (server only): try to `save' |
1172 | * the connection by checking whether entry contains the default |
1173 | * value for @feat. If yes, send an empty Confirm to signal that |
1174 | * the received Change was not understood - which implies using |
1175 | * the default value. |
1176 | * If this also fails, we use Reset as the last resort. |
1177 | */ |
1178 | WARN_ON(!server); |
1179 | defval = dccp_feat_default_value(feat); |
1180 | if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true)) |
1181 | return DCCP_RESET_CODE_OPTION_ERROR; |
1182 | entry->empty_confirm = true; |
1183 | } |
1184 | entry->needs_confirm = true; |
1185 | entry->needs_mandatory = false; |
1186 | entry->state = FEAT_STABLE; |
1187 | return 0; |
1188 | |
1189 | unknown_feature_or_value: |
1190 | if (!is_mandatory) |
1191 | return dccp_push_empty_confirm(fn, feat, local); |
1192 | |
1193 | not_valid_or_not_known: |
1194 | return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR |
1195 | : DCCP_RESET_CODE_OPTION_ERROR; |
1196 | } |
1197 | |
1198 | /** |
1199 | * dccp_feat_confirm_recv - Process received Confirm options |
1200 | * @fn: feature-negotiation list to update |
1201 | * @is_mandatory: whether @opt was preceded by a Mandatory option |
1202 | * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R |
1203 | * @feat: one of %dccp_feature_numbers |
1204 | * @val: NN value or SP value/preference list |
1205 | * @len: length of @val in bytes |
1206 | * @server: whether this node is server (1) or client (0) |
1207 | */ |
1208 | static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt, |
1209 | u8 feat, u8 *val, u8 len, const bool server) |
1210 | { |
1211 | u8 *plist, plen, type = dccp_feat_type(feat); |
1212 | const bool local = (opt == DCCPO_CONFIRM_R); |
1213 | struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local); |
1214 | |
1215 | dccp_feat_print_opt(opt, feat, val, len, is_mandatory); |
1216 | |
1217 | if (entry == NULL) { /* nothing queued: ignore or handle error */ |
1218 | if (is_mandatory && type == FEAT_UNKNOWN) |
1219 | return DCCP_RESET_CODE_MANDATORY_ERROR; |
1220 | |
1221 | if (!local && type == FEAT_NN) /* 6.3.2 */ |
1222 | goto confirmation_failed; |
1223 | return 0; |
1224 | } |
1225 | |
1226 | if (entry->state != FEAT_CHANGING) /* 6.6.2 */ |
1227 | return 0; |
1228 | |
1229 | if (len == 0) { |
1230 | if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */ |
1231 | goto confirmation_failed; |
1232 | /* |
1233 | * Empty Confirm during connection setup: this means reverting |
1234 | * to the `old' value, which in this case is the default. Since |
1235 | * we handle default values automatically when no other values |
1236 | * have been set, we revert to the old value by removing this |
1237 | * entry from the list. |
1238 | */ |
1239 | dccp_feat_list_pop(entry); |
1240 | return 0; |
1241 | } |
1242 | |
1243 | if (type == FEAT_NN) { |
1244 | if (len > sizeof(entry->val.nn)) |
1245 | goto confirmation_failed; |
1246 | |
1247 | if (entry->val.nn == dccp_decode_value_var(val, len)) |
1248 | goto confirmation_succeeded; |
1249 | |
1250 | DCCP_WARN("Bogus Confirm for non-existing value\n"); |
1251 | goto confirmation_failed; |
1252 | } |
1253 | |
1254 | /* |
1255 | * Parsing SP Confirms: the first element of @val is the preferred |
1256 | * SP value which the peer confirms, the remainder depends on @len. |
1257 | * Note that only the confirmed value need to be a valid SP value. |
1258 | */ |
1259 | if (!dccp_feat_is_valid_sp_val(feat, *val)) |
1260 | goto confirmation_failed; |
1261 | |
1262 | if (len == 1) { /* peer didn't supply a preference list */ |
1263 | plist = val; |
1264 | plen = len; |
1265 | } else { /* preferred value + preference list */ |
1266 | plist = val + 1; |
1267 | plen = len - 1; |
1268 | } |
1269 | |
1270 | /* Check whether the peer got the reconciliation right (6.6.8) */ |
1271 | if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) { |
1272 | DCCP_WARN("Confirm selected the wrong value %u\n", *val); |
1273 | return DCCP_RESET_CODE_OPTION_ERROR; |
1274 | } |
1275 | entry->val.sp.vec[0] = *val; |
1276 | |
1277 | confirmation_succeeded: |
1278 | entry->state = FEAT_STABLE; |
1279 | return 0; |
1280 | |
1281 | confirmation_failed: |
1282 | DCCP_WARN("Confirmation failed\n"); |
1283 | return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR |
1284 | : DCCP_RESET_CODE_OPTION_ERROR; |
1285 | } |
1286 | |
1287 | /** |
1288 | * dccp_feat_handle_nn_established - Fast-path reception of NN options |
1289 | * @sk: socket of an established DCCP connection |
1290 | * @mandatory: whether @opt was preceded by a Mandatory option |
1291 | * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only) |
1292 | * @feat: NN number, one of %dccp_feature_numbers |
1293 | * @val: NN value |
1294 | * @len: length of @val in bytes |
1295 | * |
1296 | * This function combines the functionality of change_recv/confirm_recv, with |
1297 | * the following differences (reset codes are the same): |
1298 | * - cleanup after receiving the Confirm; |
1299 | * - values are directly activated after successful parsing; |
1300 | * - deliberately restricted to NN features. |
1301 | * The restriction to NN features is essential since SP features can have non- |
1302 | * predictable outcomes (depending on the remote configuration), and are inter- |
1303 | * dependent (CCIDs for instance cause further dependencies). |
1304 | */ |
1305 | static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt, |
1306 | u8 feat, u8 *val, u8 len) |
1307 | { |
1308 | struct list_head *fn = &dccp_sk(sk)->dccps_featneg; |
1309 | const bool local = (opt == DCCPO_CONFIRM_R); |
1310 | struct dccp_feat_entry *entry; |
1311 | u8 type = dccp_feat_type(feat); |
1312 | dccp_feat_val fval; |
1313 | |
1314 | dccp_feat_print_opt(opt, feat, val, len, mandatory); |
1315 | |
1316 | /* Ignore non-mandatory unknown and non-NN features */ |
1317 | if (type == FEAT_UNKNOWN) { |
1318 | if (local && !mandatory) |
1319 | return 0; |
1320 | goto fast_path_unknown; |
1321 | } else if (type != FEAT_NN) { |
1322 | return 0; |
1323 | } |
1324 | |
1325 | /* |
1326 | * We don't accept empty Confirms, since in fast-path feature |
1327 | * negotiation the values are enabled immediately after sending |
1328 | * the Change option. |
1329 | * Empty Changes on the other hand are invalid (RFC 4340, 6.1). |
1330 | */ |
1331 | if (len == 0 || len > sizeof(fval.nn)) |
1332 | goto fast_path_unknown; |
1333 | |
1334 | if (opt == DCCPO_CHANGE_L) { |
1335 | fval.nn = dccp_decode_value_var(val, len); |
1336 | if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) |
1337 | goto fast_path_unknown; |
1338 | |
1339 | if (dccp_feat_push_confirm(fn, feat, local, &fval) || |
1340 | dccp_feat_activate(sk, feat, local, &fval)) |
1341 | return DCCP_RESET_CODE_TOO_BUSY; |
1342 | |
1343 | /* set the `Ack Pending' flag to piggyback a Confirm */ |
1344 | inet_csk_schedule_ack(sk); |
1345 | |
1346 | } else if (opt == DCCPO_CONFIRM_R) { |
1347 | entry = dccp_feat_list_lookup(fn, feat, local); |
1348 | if (entry == NULL || entry->state != FEAT_CHANGING) |
1349 | return 0; |
1350 | |
1351 | fval.nn = dccp_decode_value_var(val, len); |
1352 | /* |
1353 | * Just ignore a value that doesn't match our current value. |
1354 | * If the option changes twice within two RTTs, then at least |
1355 | * one CONFIRM will be received for the old value after a |
1356 | * new CHANGE was sent. |
1357 | */ |
1358 | if (fval.nn != entry->val.nn) |
1359 | return 0; |
1360 | |
1361 | /* Only activate after receiving the Confirm option (6.6.1). */ |
1362 | dccp_feat_activate(sk, feat, local, &fval); |
1363 | |
1364 | /* It has been confirmed - so remove the entry */ |
1365 | dccp_feat_list_pop(entry); |
1366 | |
1367 | } else { |
1368 | DCCP_WARN("Received illegal option %u\n", opt); |
1369 | goto fast_path_failed; |
1370 | } |
1371 | return 0; |
1372 | |
1373 | fast_path_unknown: |
1374 | if (!mandatory) |
1375 | return dccp_push_empty_confirm(fn, feat, local); |
1376 | |
1377 | fast_path_failed: |
1378 | return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR |
1379 | : DCCP_RESET_CODE_OPTION_ERROR; |
1380 | } |
1381 | |
1382 | /** |
1383 | * dccp_feat_parse_options - Process Feature-Negotiation Options |
1384 | * @sk: for general use and used by the client during connection setup |
1385 | * @dreq: used by the server during connection setup |
1386 | * @mandatory: whether @opt was preceded by a Mandatory option |
1387 | * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R |
1388 | * @feat: one of %dccp_feature_numbers |
1389 | * @val: value contents of @opt |
1390 | * @len: length of @val in bytes |
1391 | * |
1392 | * Returns 0 on success, a Reset code for ending the connection otherwise. |
1393 | */ |
1394 | int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, |
1395 | u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len) |
1396 | { |
1397 | struct dccp_sock *dp = dccp_sk(sk); |
1398 | struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; |
1399 | bool server = false; |
1400 | |
1401 | switch (sk->sk_state) { |
1402 | /* |
1403 | * Negotiation during connection setup |
1404 | */ |
1405 | case DCCP_LISTEN: |
1406 | server = true; /* fall through */ |
1407 | case DCCP_REQUESTING: |
1408 | switch (opt) { |
1409 | case DCCPO_CHANGE_L: |
1410 | case DCCPO_CHANGE_R: |
1411 | return dccp_feat_change_recv(fn, mandatory, opt, feat, |
1412 | val, len, server); |
1413 | case DCCPO_CONFIRM_R: |
1414 | case DCCPO_CONFIRM_L: |
1415 | return dccp_feat_confirm_recv(fn, mandatory, opt, feat, |
1416 | val, len, server); |
1417 | } |
1418 | break; |
1419 | /* |
1420 | * Support for exchanging NN options on an established connection. |
1421 | */ |
1422 | case DCCP_OPEN: |
1423 | case DCCP_PARTOPEN: |
1424 | return dccp_feat_handle_nn_established(sk, mandatory, opt, feat, |
1425 | val, len); |
1426 | } |
1427 | return 0; /* ignore FN options in all other states */ |
1428 | } |
1429 | |
1430 | /** |
1431 | * dccp_feat_init - Seed feature negotiation with host-specific defaults |
1432 | * This initialises global defaults, depending on the value of the sysctls. |
1433 | * These can later be overridden by registering changes via setsockopt calls. |
1434 | * The last link in the chain is finalise_settings, to make sure that between |
1435 | * here and the start of actual feature negotiation no inconsistencies enter. |
1436 | * |
1437 | * All features not appearing below use either defaults or are otherwise |
1438 | * later adjusted through dccp_feat_finalise_settings(). |
1439 | */ |
1440 | int dccp_feat_init(struct sock *sk) |
1441 | { |
1442 | struct list_head *fn = &dccp_sk(sk)->dccps_featneg; |
1443 | u8 on = 1, off = 0; |
1444 | int rc; |
1445 | struct { |
1446 | u8 *val; |
1447 | u8 len; |
1448 | } tx, rx; |
1449 | |
1450 | /* Non-negotiable (NN) features */ |
1451 | rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0, |
1452 | sysctl_dccp_sequence_window); |
1453 | if (rc) |
1454 | return rc; |
1455 | |
1456 | /* Server-priority (SP) features */ |
1457 | |
1458 | /* Advertise that short seqnos are not supported (7.6.1) */ |
1459 | rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1); |
1460 | if (rc) |
1461 | return rc; |
1462 | |
1463 | /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */ |
1464 | rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1); |
1465 | if (rc) |
1466 | return rc; |
1467 | |
1468 | /* |
1469 | * We advertise the available list of CCIDs and reorder according to |
1470 | * preferences, to avoid failure resulting from negotiating different |
1471 | * singleton values (which always leads to failure). |
1472 | * These settings can still (later) be overridden via sockopts. |
1473 | */ |
1474 | if (ccid_get_builtin_ccids(&tx.val, &tx.len) || |
1475 | ccid_get_builtin_ccids(&rx.val, &rx.len)) |
1476 | return -ENOBUFS; |
1477 | |
1478 | if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) || |
1479 | !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len)) |
1480 | goto free_ccid_lists; |
1481 | |
1482 | rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len); |
1483 | if (rc) |
1484 | goto free_ccid_lists; |
1485 | |
1486 | rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len); |
1487 | |
1488 | free_ccid_lists: |
1489 | kfree(tx.val); |
1490 | kfree(rx.val); |
1491 | return rc; |
1492 | } |
1493 | |
1494 | int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list) |
1495 | { |
1496 | struct dccp_sock *dp = dccp_sk(sk); |
1497 | struct dccp_feat_entry *cur, *next; |
1498 | int idx; |
1499 | dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = { |
1500 | [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL } |
1501 | }; |
1502 | |
1503 | list_for_each_entry(cur, fn_list, node) { |
1504 | /* |
1505 | * An empty Confirm means that either an unknown feature type |
1506 | * or an invalid value was present. In the first case there is |
1507 | * nothing to activate, in the other the default value is used. |
1508 | */ |
1509 | if (cur->empty_confirm) |
1510 | continue; |
1511 | |
1512 | idx = dccp_feat_index(cur->feat_num); |
1513 | if (idx < 0) { |
1514 | DCCP_BUG("Unknown feature %u", cur->feat_num); |
1515 | goto activation_failed; |
1516 | } |
1517 | if (cur->state != FEAT_STABLE) { |
1518 | DCCP_CRIT("Negotiation of %s %s failed in state %s", |
1519 | cur->is_local ? "local" : "remote", |
1520 | dccp_feat_fname(cur->feat_num), |
1521 | dccp_feat_sname[cur->state]); |
1522 | goto activation_failed; |
1523 | } |
1524 | fvals[idx][cur->is_local] = &cur->val; |
1525 | } |
1526 | |
1527 | /* |
1528 | * Activate in decreasing order of index, so that the CCIDs are always |
1529 | * activated as the last feature. This avoids the case where a CCID |
1530 | * relies on the initialisation of one or more features that it depends |
1531 | * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features). |
1532 | */ |
1533 | for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;) |
1534 | if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) || |
1535 | __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) { |
1536 | DCCP_CRIT("Could not activate %d", idx); |
1537 | goto activation_failed; |
1538 | } |
1539 | |
1540 | /* Clean up Change options which have been confirmed already */ |
1541 | list_for_each_entry_safe(cur, next, fn_list, node) |
1542 | if (!cur->needs_confirm) |
1543 | dccp_feat_list_pop(cur); |
1544 | |
1545 | dccp_pr_debug("Activation OK\n"); |
1546 | return 0; |
1547 | |
1548 | activation_failed: |
1549 | /* |
1550 | * We clean up everything that may have been allocated, since |
1551 | * it is difficult to track at which stage negotiation failed. |
1552 | * This is ok, since all allocation functions below are robust |
1553 | * against NULL arguments. |
1554 | */ |
1555 | ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); |
1556 | ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); |
1557 | dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; |
1558 | dccp_ackvec_free(dp->dccps_hc_rx_ackvec); |
1559 | dp->dccps_hc_rx_ackvec = NULL; |
1560 | return -1; |
1561 | } |
1562 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9