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_delay = 1; 56 msg->expires_at = 0; 57 INIT_LIST_HEAD(&msg->chunks); 58 } 59 60 /* Allocate and initialize datamsg. */ 61 static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp) 62 { 63 struct sctp_datamsg *msg; 64 msg = kmalloc(sizeof(struct sctp_datamsg), gfp); 65 if (msg) { 66 sctp_datamsg_init(msg); 67 SCTP_DBG_OBJCNT_INC(datamsg); 68 } 69 return msg; 70 } 71 72 void sctp_datamsg_free(struct sctp_datamsg *msg) 73 { 74 struct sctp_chunk *chunk; 75 76 /* This doesn't have to be a _safe vairant because 77 * sctp_chunk_free() only drops the refs. 78 */ 79 list_for_each_entry(chunk, &msg->chunks, frag_list) 80 sctp_chunk_free(chunk); 81 82 sctp_datamsg_put(msg); 83 } 84 85 /* Final destructruction of datamsg memory. */ 86 static void sctp_datamsg_destroy(struct sctp_datamsg *msg) 87 { 88 struct list_head *pos, *temp; 89 struct sctp_chunk *chunk; 90 struct sctp_sock *sp; 91 struct sctp_ulpevent *ev; 92 struct sctp_association *asoc = NULL; 93 int error = 0, notify; 94 95 /* If we failed, we may need to notify. */ 96 notify = msg->send_failed ? -1 : 0; 97 98 /* Release all references. */ 99 list_for_each_safe(pos, temp, &msg->chunks) { 100 list_del_init(pos); 101 chunk = list_entry(pos, struct sctp_chunk, frag_list); 102 /* Check whether we _really_ need to notify. */ 103 if (notify < 0) { 104 asoc = chunk->asoc; 105 if (msg->send_error) 106 error = msg->send_error; 107 else 108 error = asoc->outqueue.error; 109 110 sp = sctp_sk(asoc->base.sk); 111 notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED, 112 &sp->subscribe); 113 } 114 115 /* Generate a SEND FAILED event only if enabled. */ 116 if (notify > 0) { 117 int sent; 118 if (chunk->has_tsn) 119 sent = SCTP_DATA_SENT; 120 else 121 sent = SCTP_DATA_UNSENT; 122 123 ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent, 124 error, GFP_ATOMIC); 125 if (ev) 126 sctp_ulpq_tail_event(&asoc->ulpq, ev); 127 } 128 129 sctp_chunk_put(chunk); 130 } 131 132 SCTP_DBG_OBJCNT_DEC(datamsg); 133 kfree(msg); 134 } 135 136 /* Hold a reference. */ 137 static void sctp_datamsg_hold(struct sctp_datamsg *msg) 138 { 139 atomic_inc(&msg->refcnt); 140 } 141 142 /* Release a reference. */ 143 void sctp_datamsg_put(struct sctp_datamsg *msg) 144 { 145 if (atomic_dec_and_test(&msg->refcnt)) 146 sctp_datamsg_destroy(msg); 147 } 148 149 /* Assign a chunk to this datamsg. */ 150 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk) 151 { 152 sctp_datamsg_hold(msg); 153 chunk->msg = msg; 154 } 155 156 157 /* A data chunk can have a maximum payload of (2^16 - 20). Break 158 * down any such message into smaller chunks. Opportunistically, fragment 159 * the chunks down to the current MTU constraints. We may get refragmented 160 * later if the PMTU changes, but it is _much better_ to fragment immediately 161 * with a reasonable guess than always doing our fragmentation on the 162 * soft-interrupt. 163 */ 164 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 165 struct sctp_sndrcvinfo *sinfo, 166 struct iov_iter *from) 167 { 168 int max, whole, i, offset, over, err; 169 int len, first_len; 170 int max_data; 171 struct sctp_chunk *chunk; 172 struct sctp_datamsg *msg; 173 struct list_head *pos, *temp; 174 size_t msg_len = iov_iter_count(from); 175 __u8 frag; 176 177 msg = sctp_datamsg_new(GFP_KERNEL); 178 if (!msg) 179 return ERR_PTR(-ENOMEM); 180 181 /* Note: Calculate this outside of the loop, so that all fragments 182 * have the same expiration. 183 */ 184 if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive && 185 (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) || 186 !SCTP_PR_POLICY(sinfo->sinfo_flags))) 187 msg->expires_at = jiffies + 188 msecs_to_jiffies(sinfo->sinfo_timetolive); 189 190 /* This is the biggest possible DATA chunk that can fit into 191 * the packet 192 */ 193 max_data = asoc->pathmtu - 194 sctp_sk(asoc->base.sk)->pf->af->net_header_len - 195 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk); 196 max_data = SCTP_TRUNC4(max_data); 197 198 max = asoc->frag_point; 199 /* If the the peer requested that we authenticate DATA chunks 200 * we need to account for bundling of the AUTH chunks along with 201 * DATA. 202 */ 203 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) { 204 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc); 205 206 if (hmac_desc) 207 max_data -= SCTP_PAD4(sizeof(sctp_auth_chunk_t) + 208 hmac_desc->hmac_len); 209 } 210 211 /* Now, check if we need to reduce our max */ 212 if (max > max_data) 213 max = max_data; 214 215 whole = 0; 216 first_len = max; 217 218 /* Check to see if we have a pending SACK and try to let it be bundled 219 * with this message. Do this if we don't have any data queued already. 220 * To check that, look at out_qlen and retransmit list. 221 * NOTE: we will not reduce to account for SACK, if the message would 222 * not have been fragmented. 223 */ 224 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) && 225 asoc->outqueue.out_qlen == 0 && 226 list_empty(&asoc->outqueue.retransmit) && 227 msg_len > max) 228 max_data -= SCTP_PAD4(sizeof(sctp_sack_chunk_t)); 229 230 /* Encourage Cookie-ECHO bundling. */ 231 if (asoc->state < SCTP_STATE_COOKIE_ECHOED) 232 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN; 233 234 /* Now that we adjusted completely, reset first_len */ 235 if (first_len > max_data) 236 first_len = max_data; 237 238 /* Account for a different sized first fragment */ 239 if (msg_len >= first_len) { 240 msg_len -= first_len; 241 whole = 1; 242 msg->can_delay = 0; 243 } 244 245 /* How many full sized? How many bytes leftover? */ 246 whole += msg_len / max; 247 over = msg_len % max; 248 offset = 0; 249 250 if ((whole > 1) || (whole && over)) 251 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS); 252 253 /* Create chunks for all the full sized DATA chunks. */ 254 for (i = 0, len = first_len; i < whole; i++) { 255 frag = SCTP_DATA_MIDDLE_FRAG; 256 257 if (0 == i) 258 frag |= SCTP_DATA_FIRST_FRAG; 259 260 if ((i == (whole - 1)) && !over) { 261 frag |= SCTP_DATA_LAST_FRAG; 262 263 /* The application requests to set the I-bit of the 264 * last DATA chunk of a user message when providing 265 * the user message to the SCTP implementation. 266 */ 267 if ((sinfo->sinfo_flags & SCTP_EOF) || 268 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 269 frag |= SCTP_DATA_SACK_IMM; 270 } 271 272 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 273 0, GFP_KERNEL); 274 275 if (!chunk) { 276 err = -ENOMEM; 277 goto errout; 278 } 279 280 err = sctp_user_addto_chunk(chunk, len, from); 281 if (err < 0) 282 goto errout_chunk_free; 283 284 /* Put the chunk->skb back into the form expected by send. */ 285 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 286 - (__u8 *)chunk->skb->data); 287 288 sctp_datamsg_assign(msg, chunk); 289 list_add_tail(&chunk->frag_list, &msg->chunks); 290 291 /* The first chunk, the first chunk was likely short 292 * to allow bundling, so reset to full size. 293 */ 294 if (0 == i) 295 len = max; 296 } 297 298 /* .. now the leftover bytes. */ 299 if (over) { 300 if (!whole) 301 frag = SCTP_DATA_NOT_FRAG; 302 else 303 frag = SCTP_DATA_LAST_FRAG; 304 305 if ((sinfo->sinfo_flags & SCTP_EOF) || 306 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 307 frag |= SCTP_DATA_SACK_IMM; 308 309 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 310 0, GFP_KERNEL); 311 312 if (!chunk) { 313 err = -ENOMEM; 314 goto errout; 315 } 316 317 err = sctp_user_addto_chunk(chunk, over, from); 318 319 /* Put the chunk->skb back into the form expected by send. */ 320 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 321 - (__u8 *)chunk->skb->data); 322 if (err < 0) 323 goto errout_chunk_free; 324 325 sctp_datamsg_assign(msg, chunk); 326 list_add_tail(&chunk->frag_list, &msg->chunks); 327 } 328 329 return msg; 330 331 errout_chunk_free: 332 sctp_chunk_free(chunk); 333 334 errout: 335 list_for_each_safe(pos, temp, &msg->chunks) { 336 list_del_init(pos); 337 chunk = list_entry(pos, struct sctp_chunk, frag_list); 338 sctp_chunk_free(chunk); 339 } 340 sctp_datamsg_put(msg); 341 return ERR_PTR(err); 342 } 343 344 /* Check whether this message has expired. */ 345 int sctp_chunk_abandoned(struct sctp_chunk *chunk) 346 { 347 if (!chunk->asoc->peer.prsctp_capable) 348 return 0; 349 350 if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) && 351 time_after(jiffies, chunk->msg->expires_at)) { 352 if (chunk->sent_count) 353 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++; 354 else 355 chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++; 356 return 1; 357 } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) && 358 chunk->sent_count > chunk->sinfo.sinfo_timetolive) { 359 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++; 360 return 1; 361 } else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) && 362 chunk->msg->expires_at && 363 time_after(jiffies, chunk->msg->expires_at)) { 364 return 1; 365 } 366 /* PRIO policy is processed by sendmsg, not here */ 367 368 return 0; 369 } 370 371 /* This chunk (and consequently entire message) has failed in its sending. */ 372 void sctp_chunk_fail(struct sctp_chunk *chunk, int error) 373 { 374 chunk->msg->send_failed = 1; 375 chunk->msg->send_error = error; 376 } 377