1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* SCTP kernel implementation |
3 | * (C) Copyright IBM Corp. 2001, 2004 |
4 | * Copyright (c) 1999-2000 Cisco, Inc. |
5 | * Copyright (c) 1999-2001 Motorola, Inc. |
6 | * Copyright (c) 2001 Intel Corp. |
7 | * |
8 | * This file is part of the SCTP kernel implementation |
9 | * |
10 | * These functions manipulate sctp tsn mapping array. |
11 | * |
12 | * Please send any bug reports or fixes you make to the |
13 | * email address(es): |
14 | * lksctp developers <linux-sctp@vger.kernel.org> |
15 | * |
16 | * Written or modified by: |
17 | * La Monte H.P. Yarroll <piggy@acm.org> |
18 | * Jon Grimm <jgrimm@us.ibm.com> |
19 | * Karl Knutson <karl@athena.chicago.il.us> |
20 | * Sridhar Samudrala <sri@us.ibm.com> |
21 | */ |
22 | |
23 | #include <linux/slab.h> |
24 | #include <linux/types.h> |
25 | #include <linux/bitmap.h> |
26 | #include <net/sctp/sctp.h> |
27 | #include <net/sctp/sm.h> |
28 | |
29 | static void sctp_tsnmap_update(struct sctp_tsnmap *map); |
30 | static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off, |
31 | __u16 len, __u16 *start, __u16 *end); |
32 | static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 size); |
33 | |
34 | /* Initialize a block of memory as a tsnmap. */ |
35 | struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len, |
36 | __u32 initial_tsn, gfp_t gfp) |
37 | { |
38 | if (!map->tsn_map) { |
39 | map->tsn_map = kzalloc(size: len>>3, flags: gfp); |
40 | if (map->tsn_map == NULL) |
41 | return NULL; |
42 | |
43 | map->len = len; |
44 | } else { |
45 | bitmap_zero(dst: map->tsn_map, nbits: map->len); |
46 | } |
47 | |
48 | /* Keep track of TSNs represented by tsn_map. */ |
49 | map->base_tsn = initial_tsn; |
50 | map->cumulative_tsn_ack_point = initial_tsn - 1; |
51 | map->max_tsn_seen = map->cumulative_tsn_ack_point; |
52 | map->num_dup_tsns = 0; |
53 | |
54 | return map; |
55 | } |
56 | |
57 | void sctp_tsnmap_free(struct sctp_tsnmap *map) |
58 | { |
59 | map->len = 0; |
60 | kfree(objp: map->tsn_map); |
61 | } |
62 | |
63 | /* Test the tracking state of this TSN. |
64 | * Returns: |
65 | * 0 if the TSN has not yet been seen |
66 | * >0 if the TSN has been seen (duplicate) |
67 | * <0 if the TSN is invalid (too large to track) |
68 | */ |
69 | int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn) |
70 | { |
71 | u32 gap; |
72 | |
73 | /* Check to see if this is an old TSN */ |
74 | if (TSN_lte(tsn, map->cumulative_tsn_ack_point)) |
75 | return 1; |
76 | |
77 | /* Verify that we can hold this TSN and that it will not |
78 | * overflow our map |
79 | */ |
80 | if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) |
81 | return -1; |
82 | |
83 | /* Calculate the index into the mapping arrays. */ |
84 | gap = tsn - map->base_tsn; |
85 | |
86 | /* Check to see if TSN has already been recorded. */ |
87 | if (gap < map->len && test_bit(gap, map->tsn_map)) |
88 | return 1; |
89 | else |
90 | return 0; |
91 | } |
92 | |
93 | |
94 | /* Mark this TSN as seen. */ |
95 | int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn, |
96 | struct sctp_transport *trans) |
97 | { |
98 | u16 gap; |
99 | |
100 | if (TSN_lt(tsn, map->base_tsn)) |
101 | return 0; |
102 | |
103 | gap = tsn - map->base_tsn; |
104 | |
105 | if (gap >= map->len && !sctp_tsnmap_grow(map, size: gap + 1)) |
106 | return -ENOMEM; |
107 | |
108 | if (!sctp_tsnmap_has_gap(map) && gap == 0) { |
109 | /* In this case the map has no gaps and the tsn we are |
110 | * recording is the next expected tsn. We don't touch |
111 | * the map but simply bump the values. |
112 | */ |
113 | map->max_tsn_seen++; |
114 | map->cumulative_tsn_ack_point++; |
115 | if (trans) |
116 | trans->sack_generation = |
117 | trans->asoc->peer.sack_generation; |
118 | map->base_tsn++; |
119 | } else { |
120 | /* Either we already have a gap, or about to record a gap, so |
121 | * have work to do. |
122 | * |
123 | * Bump the max. |
124 | */ |
125 | if (TSN_lt(map->max_tsn_seen, tsn)) |
126 | map->max_tsn_seen = tsn; |
127 | |
128 | /* Mark the TSN as received. */ |
129 | set_bit(nr: gap, addr: map->tsn_map); |
130 | |
131 | /* Go fixup any internal TSN mapping variables including |
132 | * cumulative_tsn_ack_point. |
133 | */ |
134 | sctp_tsnmap_update(map); |
135 | } |
136 | |
137 | return 0; |
138 | } |
139 | |
140 | |
141 | /* Initialize a Gap Ack Block iterator from memory being provided. */ |
142 | static void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map, |
143 | struct sctp_tsnmap_iter *iter) |
144 | { |
145 | /* Only start looking one past the Cumulative TSN Ack Point. */ |
146 | iter->start = map->cumulative_tsn_ack_point + 1; |
147 | } |
148 | |
149 | /* Get the next Gap Ack Blocks. Returns 0 if there was not another block |
150 | * to get. |
151 | */ |
152 | static int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map, |
153 | struct sctp_tsnmap_iter *iter, |
154 | __u16 *start, __u16 *end) |
155 | { |
156 | int ended = 0; |
157 | __u16 start_ = 0, end_ = 0, offset; |
158 | |
159 | /* If there are no more gap acks possible, get out fast. */ |
160 | if (TSN_lte(map->max_tsn_seen, iter->start)) |
161 | return 0; |
162 | |
163 | offset = iter->start - map->base_tsn; |
164 | sctp_tsnmap_find_gap_ack(map: map->tsn_map, off: offset, len: map->len, |
165 | start: &start_, end: &end_); |
166 | |
167 | /* The Gap Ack Block happens to end at the end of the map. */ |
168 | if (start_ && !end_) |
169 | end_ = map->len - 1; |
170 | |
171 | /* If we found a Gap Ack Block, return the start and end and |
172 | * bump the iterator forward. |
173 | */ |
174 | if (end_) { |
175 | /* Fix up the start and end based on the |
176 | * Cumulative TSN Ack which is always 1 behind base. |
177 | */ |
178 | *start = start_ + 1; |
179 | *end = end_ + 1; |
180 | |
181 | /* Move the iterator forward. */ |
182 | iter->start = map->cumulative_tsn_ack_point + *end + 1; |
183 | ended = 1; |
184 | } |
185 | |
186 | return ended; |
187 | } |
188 | |
189 | /* Mark this and any lower TSN as seen. */ |
190 | void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn) |
191 | { |
192 | u32 gap; |
193 | |
194 | if (TSN_lt(tsn, map->base_tsn)) |
195 | return; |
196 | if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) |
197 | return; |
198 | |
199 | /* Bump the max. */ |
200 | if (TSN_lt(map->max_tsn_seen, tsn)) |
201 | map->max_tsn_seen = tsn; |
202 | |
203 | gap = tsn - map->base_tsn + 1; |
204 | |
205 | map->base_tsn += gap; |
206 | map->cumulative_tsn_ack_point += gap; |
207 | if (gap >= map->len) { |
208 | /* If our gap is larger then the map size, just |
209 | * zero out the map. |
210 | */ |
211 | bitmap_zero(dst: map->tsn_map, nbits: map->len); |
212 | } else { |
213 | /* If the gap is smaller than the map size, |
214 | * shift the map by 'gap' bits and update further. |
215 | */ |
216 | bitmap_shift_right(dst: map->tsn_map, src: map->tsn_map, shift: gap, nbits: map->len); |
217 | sctp_tsnmap_update(map); |
218 | } |
219 | } |
220 | |
221 | /******************************************************************** |
222 | * 2nd Level Abstractions |
223 | ********************************************************************/ |
224 | |
225 | /* This private helper function updates the tsnmap buffers and |
226 | * the Cumulative TSN Ack Point. |
227 | */ |
228 | static void sctp_tsnmap_update(struct sctp_tsnmap *map) |
229 | { |
230 | u16 len; |
231 | unsigned long zero_bit; |
232 | |
233 | |
234 | len = map->max_tsn_seen - map->cumulative_tsn_ack_point; |
235 | zero_bit = find_first_zero_bit(addr: map->tsn_map, size: len); |
236 | if (!zero_bit) |
237 | return; /* The first 0-bit is bit 0. nothing to do */ |
238 | |
239 | map->base_tsn += zero_bit; |
240 | map->cumulative_tsn_ack_point += zero_bit; |
241 | |
242 | bitmap_shift_right(dst: map->tsn_map, src: map->tsn_map, shift: zero_bit, nbits: map->len); |
243 | } |
244 | |
245 | /* How many data chunks are we missing from our peer? |
246 | */ |
247 | __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map) |
248 | { |
249 | __u32 cum_tsn = map->cumulative_tsn_ack_point; |
250 | __u32 max_tsn = map->max_tsn_seen; |
251 | __u32 base_tsn = map->base_tsn; |
252 | __u16 pending_data; |
253 | u32 gap; |
254 | |
255 | pending_data = max_tsn - cum_tsn; |
256 | gap = max_tsn - base_tsn; |
257 | |
258 | if (gap == 0 || gap >= map->len) |
259 | goto out; |
260 | |
261 | pending_data -= bitmap_weight(src: map->tsn_map, nbits: gap + 1); |
262 | out: |
263 | return pending_data; |
264 | } |
265 | |
266 | /* This is a private helper for finding Gap Ack Blocks. It searches a |
267 | * single array for the start and end of a Gap Ack Block. |
268 | * |
269 | * The flags "started" and "ended" tell is if we found the beginning |
270 | * or (respectively) the end of a Gap Ack Block. |
271 | */ |
272 | static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off, |
273 | __u16 len, __u16 *start, __u16 *end) |
274 | { |
275 | int i = off; |
276 | |
277 | /* Look through the entire array, but break out |
278 | * early if we have found the end of the Gap Ack Block. |
279 | */ |
280 | |
281 | /* Also, stop looking past the maximum TSN seen. */ |
282 | |
283 | /* Look for the start. */ |
284 | i = find_next_bit(addr: map, size: len, offset: off); |
285 | if (i < len) |
286 | *start = i; |
287 | |
288 | /* Look for the end. */ |
289 | if (*start) { |
290 | /* We have found the start, let's find the |
291 | * end. If we find the end, break out. |
292 | */ |
293 | i = find_next_zero_bit(addr: map, size: len, offset: i); |
294 | if (i < len) |
295 | *end = i - 1; |
296 | } |
297 | } |
298 | |
299 | /* Renege that we have seen a TSN. */ |
300 | void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn) |
301 | { |
302 | u32 gap; |
303 | |
304 | if (TSN_lt(tsn, map->base_tsn)) |
305 | return; |
306 | /* Assert: TSN is in range. */ |
307 | if (!TSN_lt(tsn, map->base_tsn + map->len)) |
308 | return; |
309 | |
310 | gap = tsn - map->base_tsn; |
311 | |
312 | /* Pretend we never saw the TSN. */ |
313 | clear_bit(nr: gap, addr: map->tsn_map); |
314 | } |
315 | |
316 | /* How many gap ack blocks do we have recorded? */ |
317 | __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map, |
318 | struct sctp_gap_ack_block *gabs) |
319 | { |
320 | struct sctp_tsnmap_iter iter; |
321 | int ngaps = 0; |
322 | |
323 | /* Refresh the gap ack information. */ |
324 | if (sctp_tsnmap_has_gap(map)) { |
325 | __u16 start = 0, end = 0; |
326 | sctp_tsnmap_iter_init(map, iter: &iter); |
327 | while (sctp_tsnmap_next_gap_ack(map, iter: &iter, |
328 | start: &start, |
329 | end: &end)) { |
330 | |
331 | gabs[ngaps].start = htons(start); |
332 | gabs[ngaps].end = htons(end); |
333 | ngaps++; |
334 | if (ngaps >= SCTP_MAX_GABS) |
335 | break; |
336 | } |
337 | } |
338 | return ngaps; |
339 | } |
340 | |
341 | static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 size) |
342 | { |
343 | unsigned long *new; |
344 | unsigned long inc; |
345 | u16 len; |
346 | |
347 | if (size > SCTP_TSN_MAP_SIZE) |
348 | return 0; |
349 | |
350 | inc = ALIGN((size - map->len), BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT; |
351 | len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE); |
352 | |
353 | new = kzalloc(size: len>>3, GFP_ATOMIC); |
354 | if (!new) |
355 | return 0; |
356 | |
357 | bitmap_copy(dst: new, src: map->tsn_map, |
358 | nbits: map->max_tsn_seen - map->cumulative_tsn_ack_point); |
359 | kfree(objp: map->tsn_map); |
360 | map->tsn_map = new; |
361 | map->len = len; |
362 | |
363 | return 1; |
364 | } |
365 | |