| 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(len>>3, gfp); |
| 40 | if (map->tsn_map == NULL) |
| 41 | return NULL; |
| 42 | |
| 43 | map->len = len; |
| 44 | } else { |
| 45 | bitmap_zero(map->tsn_map, 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(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, 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(gap, 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->tsn_map, offset, map->len, |
| 165 | &start_, &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(map->tsn_map, 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(map->tsn_map, map->tsn_map, gap, 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(map->tsn_map, 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(map->tsn_map, map->tsn_map, zero_bit, 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(map->tsn_map, 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(map, len, 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(map, len, 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(gap, 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); |
| 327 | while (sctp_tsnmap_next_gap_ack(map, &iter, |
| 328 | &start, |
| 329 | &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(len>>3, GFP_ATOMIC); |
| 354 | if (!new) |
| 355 | return 0; |
| 356 | |
| 357 | bitmap_copy(new, map->tsn_map, |
| 358 | map->max_tsn_seen - map->cumulative_tsn_ack_point); |
| 359 | kfree(map->tsn_map); |
| 360 | map->tsn_map = new; |
| 361 | map->len = len; |
| 362 | |
| 363 | return 1; |
| 364 | } |