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 } 365