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 /* This is the biggest possible DATA chunk that can fit into 196 * the packet 197 */ 198 max_data = (asoc->pathmtu - 199 sctp_sk(asoc->base.sk)->pf->af->net_header_len - 200 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk)) & ~3; 201 202 max = asoc->frag_point; 203 /* If the the peer requested that we authenticate DATA chunks 204 * we need to account for bundling of the AUTH chunks along with 205 * DATA. 206 */ 207 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) { 208 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc); 209 210 if (hmac_desc) 211 max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) + 212 hmac_desc->hmac_len); 213 } 214 215 /* Now, check if we need to reduce our max */ 216 if (max > max_data) 217 max = max_data; 218 219 whole = 0; 220 first_len = max; 221 222 /* Check to see if we have a pending SACK and try to let it be bundled 223 * with this message. Do this if we don't have any data queued already. 224 * To check that, look at out_qlen and retransmit list. 225 * NOTE: we will not reduce to account for SACK, if the message would 226 * not have been fragmented. 227 */ 228 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) && 229 asoc->outqueue.out_qlen == 0 && 230 list_empty(&asoc->outqueue.retransmit) && 231 msg_len > max) 232 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t)); 233 234 /* Encourage Cookie-ECHO bundling. */ 235 if (asoc->state < SCTP_STATE_COOKIE_ECHOED) 236 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN; 237 238 /* Now that we adjusted completely, reset first_len */ 239 if (first_len > max_data) 240 first_len = max_data; 241 242 /* Account for a different sized first fragment */ 243 if (msg_len >= first_len) { 244 msg_len -= first_len; 245 whole = 1; 246 msg->can_delay = 0; 247 } 248 249 /* How many full sized? How many bytes leftover? */ 250 whole += msg_len / max; 251 over = msg_len % max; 252 offset = 0; 253 254 if ((whole > 1) || (whole && over)) 255 SCTP_INC_STATS_USER(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS); 256 257 /* Create chunks for all the full sized DATA chunks. */ 258 for (i = 0, len = first_len; i < whole; i++) { 259 frag = SCTP_DATA_MIDDLE_FRAG; 260 261 if (0 == i) 262 frag |= SCTP_DATA_FIRST_FRAG; 263 264 if ((i == (whole - 1)) && !over) { 265 frag |= SCTP_DATA_LAST_FRAG; 266 267 /* The application requests to set the I-bit of the 268 * last DATA chunk of a user message when providing 269 * the user message to the SCTP implementation. 270 */ 271 if ((sinfo->sinfo_flags & SCTP_EOF) || 272 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 273 frag |= SCTP_DATA_SACK_IMM; 274 } 275 276 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0); 277 278 if (!chunk) { 279 err = -ENOMEM; 280 goto errout; 281 } 282 283 err = sctp_user_addto_chunk(chunk, len, from); 284 if (err < 0) 285 goto errout_chunk_free; 286 287 /* Put the chunk->skb back into the form expected by send. */ 288 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 289 - (__u8 *)chunk->skb->data); 290 291 sctp_datamsg_assign(msg, chunk); 292 list_add_tail(&chunk->frag_list, &msg->chunks); 293 294 /* The first chunk, the first chunk was likely short 295 * to allow bundling, so reset to full size. 296 */ 297 if (0 == i) 298 len = max; 299 } 300 301 /* .. now the leftover bytes. */ 302 if (over) { 303 if (!whole) 304 frag = SCTP_DATA_NOT_FRAG; 305 else 306 frag = SCTP_DATA_LAST_FRAG; 307 308 if ((sinfo->sinfo_flags & SCTP_EOF) || 309 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 310 frag |= SCTP_DATA_SACK_IMM; 311 312 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0); 313 314 if (!chunk) { 315 err = -ENOMEM; 316 goto errout; 317 } 318 319 err = sctp_user_addto_chunk(chunk, over, from); 320 321 /* Put the chunk->skb back into the form expected by send. */ 322 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 323 - (__u8 *)chunk->skb->data); 324 if (err < 0) 325 goto errout_chunk_free; 326 327 sctp_datamsg_assign(msg, chunk); 328 list_add_tail(&chunk->frag_list, &msg->chunks); 329 } 330 331 return msg; 332 333 errout_chunk_free: 334 sctp_chunk_free(chunk); 335 336 errout: 337 list_for_each_safe(pos, temp, &msg->chunks) { 338 list_del_init(pos); 339 chunk = list_entry(pos, struct sctp_chunk, frag_list); 340 sctp_chunk_free(chunk); 341 } 342 sctp_datamsg_put(msg); 343 return ERR_PTR(err); 344 } 345 346 /* Check whether this message has expired. */ 347 int sctp_chunk_abandoned(struct sctp_chunk *chunk) 348 { 349 struct sctp_datamsg *msg = chunk->msg; 350 351 if (!msg->can_abandon) 352 return 0; 353 354 if (time_after(jiffies, msg->expires_at)) 355 return 1; 356 357 return 0; 358 } 359 360 /* This chunk (and consequently entire message) has failed in its sending. */ 361 void sctp_chunk_fail(struct sctp_chunk *chunk, int error) 362 { 363 chunk->msg->send_failed = 1; 364 chunk->msg->send_error = error; 365 } 366