1 /* SCTP kernel implementation 2 * (C) Copyright IBM Corp. 2003, 2004 3 * 4 * This file is part of the SCTP kernel implementation 5 * 6 * This file contains the code relating the chunk abstraction. 7 * 8 * This SCTP implementation is free software; 9 * you can redistribute it and/or modify it under the terms of 10 * the GNU General Public License as published by 11 * the Free Software Foundation; either version 2, or (at your option) 12 * any later version. 13 * 14 * This SCTP implementation is distributed in the hope that it 15 * will be useful, but WITHOUT ANY WARRANTY; without even the implied 16 * ************************ 17 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 18 * See the GNU General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License 21 * along with GNU CC; see the file COPYING. If not, see 22 * <http://www.gnu.org/licenses/>. 23 * 24 * Please send any bug reports or fixes you make to the 25 * email address(es): 26 * lksctp developers <linux-sctp@vger.kernel.org> 27 * 28 * Written or modified by: 29 * Jon Grimm <jgrimm@us.ibm.com> 30 * Sridhar Samudrala <sri@us.ibm.com> 31 */ 32 33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 34 35 #include <linux/types.h> 36 #include <linux/kernel.h> 37 #include <linux/net.h> 38 #include <linux/inet.h> 39 #include <linux/skbuff.h> 40 #include <linux/slab.h> 41 #include <net/sock.h> 42 #include <net/sctp/sctp.h> 43 #include <net/sctp/sm.h> 44 45 /* This file is mostly in anticipation of future work, but initially 46 * populate with fragment tracking for an outbound message. 47 */ 48 49 /* Initialize datamsg from memory. */ 50 static void sctp_datamsg_init(struct sctp_datamsg *msg) 51 { 52 atomic_set(&msg->refcnt, 1); 53 msg->send_failed = 0; 54 msg->send_error = 0; 55 msg->can_abandon = 0; 56 msg->can_delay = 1; 57 msg->expires_at = 0; 58 INIT_LIST_HEAD(&msg->chunks); 59 } 60 61 /* Allocate and initialize datamsg. */ 62 static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp) 63 { 64 struct sctp_datamsg *msg; 65 msg = kmalloc(sizeof(struct sctp_datamsg), gfp); 66 if (msg) { 67 sctp_datamsg_init(msg); 68 SCTP_DBG_OBJCNT_INC(datamsg); 69 } 70 return msg; 71 } 72 73 void sctp_datamsg_free(struct sctp_datamsg *msg) 74 { 75 struct sctp_chunk *chunk; 76 77 /* This doesn't have to be a _safe vairant because 78 * sctp_chunk_free() only drops the refs. 79 */ 80 list_for_each_entry(chunk, &msg->chunks, frag_list) 81 sctp_chunk_free(chunk); 82 83 sctp_datamsg_put(msg); 84 } 85 86 /* Final destructruction of datamsg memory. */ 87 static void sctp_datamsg_destroy(struct sctp_datamsg *msg) 88 { 89 struct list_head *pos, *temp; 90 struct sctp_chunk *chunk; 91 struct sctp_sock *sp; 92 struct sctp_ulpevent *ev; 93 struct sctp_association *asoc = NULL; 94 int error = 0, notify; 95 96 /* If we failed, we may need to notify. */ 97 notify = msg->send_failed ? -1 : 0; 98 99 /* Release all references. */ 100 list_for_each_safe(pos, temp, &msg->chunks) { 101 list_del_init(pos); 102 chunk = list_entry(pos, struct sctp_chunk, frag_list); 103 /* Check whether we _really_ need to notify. */ 104 if (notify < 0) { 105 asoc = chunk->asoc; 106 if (msg->send_error) 107 error = msg->send_error; 108 else 109 error = asoc->outqueue.error; 110 111 sp = sctp_sk(asoc->base.sk); 112 notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED, 113 &sp->subscribe); 114 } 115 116 /* Generate a SEND FAILED event only if enabled. */ 117 if (notify > 0) { 118 int sent; 119 if (chunk->has_tsn) 120 sent = SCTP_DATA_SENT; 121 else 122 sent = SCTP_DATA_UNSENT; 123 124 ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent, 125 error, GFP_ATOMIC); 126 if (ev) 127 sctp_ulpq_tail_event(&asoc->ulpq, ev); 128 } 129 130 sctp_chunk_put(chunk); 131 } 132 133 SCTP_DBG_OBJCNT_DEC(datamsg); 134 kfree(msg); 135 } 136 137 /* Hold a reference. */ 138 static void sctp_datamsg_hold(struct sctp_datamsg *msg) 139 { 140 atomic_inc(&msg->refcnt); 141 } 142 143 /* Release a reference. */ 144 void sctp_datamsg_put(struct sctp_datamsg *msg) 145 { 146 if (atomic_dec_and_test(&msg->refcnt)) 147 sctp_datamsg_destroy(msg); 148 } 149 150 /* Assign a chunk to this datamsg. */ 151 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk) 152 { 153 sctp_datamsg_hold(msg); 154 chunk->msg = msg; 155 } 156 157 158 /* A data chunk can have a maximum payload of (2^16 - 20). Break 159 * down any such message into smaller chunks. Opportunistically, fragment 160 * the chunks down to the current MTU constraints. We may get refragmented 161 * later if the PMTU changes, but it is _much better_ to fragment immediately 162 * with a reasonable guess than always doing our fragmentation on the 163 * soft-interrupt. 164 */ 165 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 166 struct sctp_sndrcvinfo *sinfo, 167 struct iov_iter *from) 168 { 169 int max, whole, i, offset, over, err; 170 int len, first_len; 171 int max_data; 172 struct sctp_chunk *chunk; 173 struct sctp_datamsg *msg; 174 struct list_head *pos, *temp; 175 size_t msg_len = iov_iter_count(from); 176 __u8 frag; 177 178 msg = sctp_datamsg_new(GFP_KERNEL); 179 if (!msg) 180 return ERR_PTR(-ENOMEM); 181 182 /* Note: Calculate this outside of the loop, so that all fragments 183 * have the same expiration. 184 */ 185 if (sinfo->sinfo_timetolive) { 186 /* sinfo_timetolive is in milliseconds */ 187 msg->expires_at = jiffies + 188 msecs_to_jiffies(sinfo->sinfo_timetolive); 189 msg->can_abandon = 1; 190 191 pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__, 192 msg, msg->expires_at, jiffies); 193 } 194 195 if (asoc->peer.prsctp_capable && 196 SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags)) 197 msg->expires_at = 198 jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive); 199 200 /* This is the biggest possible DATA chunk that can fit into 201 * the packet 202 */ 203 max_data = asoc->pathmtu - 204 sctp_sk(asoc->base.sk)->pf->af->net_header_len - 205 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk); 206 max_data = SCTP_TRUNC4(max_data); 207 208 max = asoc->frag_point; 209 /* If the the peer requested that we authenticate DATA chunks 210 * we need to account for bundling of the AUTH chunks along with 211 * DATA. 212 */ 213 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) { 214 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc); 215 216 if (hmac_desc) 217 max_data -= SCTP_PAD4(sizeof(sctp_auth_chunk_t) + 218 hmac_desc->hmac_len); 219 } 220 221 /* Now, check if we need to reduce our max */ 222 if (max > max_data) 223 max = max_data; 224 225 whole = 0; 226 first_len = max; 227 228 /* Check to see if we have a pending SACK and try to let it be bundled 229 * with this message. Do this if we don't have any data queued already. 230 * To check that, look at out_qlen and retransmit list. 231 * NOTE: we will not reduce to account for SACK, if the message would 232 * not have been fragmented. 233 */ 234 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) && 235 asoc->outqueue.out_qlen == 0 && 236 list_empty(&asoc->outqueue.retransmit) && 237 msg_len > max) 238 max_data -= SCTP_PAD4(sizeof(sctp_sack_chunk_t)); 239 240 /* Encourage Cookie-ECHO bundling. */ 241 if (asoc->state < SCTP_STATE_COOKIE_ECHOED) 242 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN; 243 244 /* Now that we adjusted completely, reset first_len */ 245 if (first_len > max_data) 246 first_len = max_data; 247 248 /* Account for a different sized first fragment */ 249 if (msg_len >= first_len) { 250 msg_len -= first_len; 251 whole = 1; 252 msg->can_delay = 0; 253 } 254 255 /* How many full sized? How many bytes leftover? */ 256 whole += msg_len / max; 257 over = msg_len % max; 258 offset = 0; 259 260 if ((whole > 1) || (whole && over)) 261 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS); 262 263 /* Create chunks for all the full sized DATA chunks. */ 264 for (i = 0, len = first_len; i < whole; i++) { 265 frag = SCTP_DATA_MIDDLE_FRAG; 266 267 if (0 == i) 268 frag |= SCTP_DATA_FIRST_FRAG; 269 270 if ((i == (whole - 1)) && !over) { 271 frag |= SCTP_DATA_LAST_FRAG; 272 273 /* The application requests to set the I-bit of the 274 * last DATA chunk of a user message when providing 275 * the user message to the SCTP implementation. 276 */ 277 if ((sinfo->sinfo_flags & SCTP_EOF) || 278 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 279 frag |= SCTP_DATA_SACK_IMM; 280 } 281 282 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 283 0, GFP_KERNEL); 284 285 if (!chunk) { 286 err = -ENOMEM; 287 goto errout; 288 } 289 290 err = sctp_user_addto_chunk(chunk, len, from); 291 if (err < 0) 292 goto errout_chunk_free; 293 294 /* Put the chunk->skb back into the form expected by send. */ 295 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 296 - (__u8 *)chunk->skb->data); 297 298 sctp_datamsg_assign(msg, chunk); 299 list_add_tail(&chunk->frag_list, &msg->chunks); 300 301 /* The first chunk, the first chunk was likely short 302 * to allow bundling, so reset to full size. 303 */ 304 if (0 == i) 305 len = max; 306 } 307 308 /* .. now the leftover bytes. */ 309 if (over) { 310 if (!whole) 311 frag = SCTP_DATA_NOT_FRAG; 312 else 313 frag = SCTP_DATA_LAST_FRAG; 314 315 if ((sinfo->sinfo_flags & SCTP_EOF) || 316 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 317 frag |= SCTP_DATA_SACK_IMM; 318 319 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 320 0, GFP_KERNEL); 321 322 if (!chunk) { 323 err = -ENOMEM; 324 goto errout; 325 } 326 327 err = sctp_user_addto_chunk(chunk, over, from); 328 329 /* Put the chunk->skb back into the form expected by send. */ 330 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 331 - (__u8 *)chunk->skb->data); 332 if (err < 0) 333 goto errout_chunk_free; 334 335 sctp_datamsg_assign(msg, chunk); 336 list_add_tail(&chunk->frag_list, &msg->chunks); 337 } 338 339 return msg; 340 341 errout_chunk_free: 342 sctp_chunk_free(chunk); 343 344 errout: 345 list_for_each_safe(pos, temp, &msg->chunks) { 346 list_del_init(pos); 347 chunk = list_entry(pos, struct sctp_chunk, frag_list); 348 sctp_chunk_free(chunk); 349 } 350 sctp_datamsg_put(msg); 351 return ERR_PTR(err); 352 } 353 354 /* Check whether this message has expired. */ 355 int sctp_chunk_abandoned(struct sctp_chunk *chunk) 356 { 357 if (!chunk->asoc->peer.prsctp_capable || 358 !SCTP_PR_POLICY(chunk->sinfo.sinfo_flags)) { 359 struct sctp_datamsg *msg = chunk->msg; 360 361 if (!msg->can_abandon) 362 return 0; 363 364 if (time_after(jiffies, msg->expires_at)) 365 return 1; 366 367 return 0; 368 } 369 370 if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) && 371 time_after(jiffies, chunk->msg->expires_at)) { 372 if (chunk->sent_count) 373 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++; 374 else 375 chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++; 376 return 1; 377 } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) && 378 chunk->sent_count > chunk->sinfo.sinfo_timetolive) { 379 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++; 380 return 1; 381 } 382 /* PRIO policy is processed by sendmsg, not here */ 383 384 return 0; 385 } 386 387 /* This chunk (and consequently entire message) has failed in its sending. */ 388 void sctp_chunk_fail(struct sctp_chunk *chunk, int error) 389 { 390 chunk->msg->send_failed = 1; 391 chunk->msg->send_error = error; 392 } 393