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 msghdr *msgh, int msg_len) 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 __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 (sinfo->sinfo_timetolive) { 185 /* sinfo_timetolive is in milliseconds */ 186 msg->expires_at = jiffies + 187 msecs_to_jiffies(sinfo->sinfo_timetolive); 188 msg->can_abandon = 1; 189 190 pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__, 191 msg, msg->expires_at, jiffies); 192 } 193 194 /* This is the biggest possible DATA chunk that can fit into 195 * the packet 196 */ 197 max_data = (asoc->pathmtu - 198 sctp_sk(asoc->base.sk)->pf->af->net_header_len - 199 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk)) & ~3; 200 201 max = asoc->frag_point; 202 /* If the the peer requested that we authenticate DATA chunks 203 * we need to account for bundling of the AUTH chunks along with 204 * DATA. 205 */ 206 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) { 207 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc); 208 209 if (hmac_desc) 210 max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) + 211 hmac_desc->hmac_len); 212 } 213 214 /* Now, check if we need to reduce our max */ 215 if (max > max_data) 216 max = max_data; 217 218 whole = 0; 219 first_len = max; 220 221 /* Check to see if we have a pending SACK and try to let it be bundled 222 * with this message. Do this if we don't have any data queued already. 223 * To check that, look at out_qlen and retransmit list. 224 * NOTE: we will not reduce to account for SACK, if the message would 225 * not have been fragmented. 226 */ 227 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) && 228 asoc->outqueue.out_qlen == 0 && 229 list_empty(&asoc->outqueue.retransmit) && 230 msg_len > max) 231 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t)); 232 233 /* Encourage Cookie-ECHO bundling. */ 234 if (asoc->state < SCTP_STATE_COOKIE_ECHOED) 235 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN; 236 237 /* Now that we adjusted completely, reset first_len */ 238 if (first_len > max_data) 239 first_len = max_data; 240 241 /* Account for a different sized first fragment */ 242 if (msg_len >= first_len) { 243 msg_len -= first_len; 244 whole = 1; 245 msg->can_delay = 0; 246 } 247 248 /* How many full sized? How many bytes leftover? */ 249 whole += msg_len / max; 250 over = msg_len % max; 251 offset = 0; 252 253 if ((whole > 1) || (whole && over)) 254 SCTP_INC_STATS_USER(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS); 255 256 /* Create chunks for all the full sized DATA chunks. */ 257 for (i = 0, len = first_len; i < whole; i++) { 258 frag = SCTP_DATA_MIDDLE_FRAG; 259 260 if (0 == i) 261 frag |= SCTP_DATA_FIRST_FRAG; 262 263 if ((i == (whole - 1)) && !over) { 264 frag |= SCTP_DATA_LAST_FRAG; 265 266 /* The application requests to set the I-bit of the 267 * last DATA chunk of a user message when providing 268 * the user message to the SCTP implementation. 269 */ 270 if ((sinfo->sinfo_flags & SCTP_EOF) || 271 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 272 frag |= SCTP_DATA_SACK_IMM; 273 } 274 275 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0); 276 277 if (!chunk) { 278 err = -ENOMEM; 279 goto errout; 280 } 281 282 err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov); 283 if (err < 0) 284 goto errout_chunk_free; 285 286 offset += len; 287 288 /* Put the chunk->skb back into the form expected by send. */ 289 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 290 - (__u8 *)chunk->skb->data); 291 292 sctp_datamsg_assign(msg, chunk); 293 list_add_tail(&chunk->frag_list, &msg->chunks); 294 295 /* The first chunk, the first chunk was likely short 296 * to allow bundling, so reset to full size. 297 */ 298 if (0 == i) 299 len = max; 300 } 301 302 /* .. now the leftover bytes. */ 303 if (over) { 304 if (!whole) 305 frag = SCTP_DATA_NOT_FRAG; 306 else 307 frag = SCTP_DATA_LAST_FRAG; 308 309 if ((sinfo->sinfo_flags & SCTP_EOF) || 310 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 311 frag |= SCTP_DATA_SACK_IMM; 312 313 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0); 314 315 if (!chunk) { 316 err = -ENOMEM; 317 goto errout; 318 } 319 320 err = sctp_user_addto_chunk(chunk, offset, over, msgh->msg_iov); 321 322 /* Put the chunk->skb back into the form expected by send. */ 323 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 324 - (__u8 *)chunk->skb->data); 325 if (err < 0) 326 goto errout_chunk_free; 327 328 sctp_datamsg_assign(msg, chunk); 329 list_add_tail(&chunk->frag_list, &msg->chunks); 330 } 331 332 return msg; 333 334 errout_chunk_free: 335 sctp_chunk_free(chunk); 336 337 errout: 338 list_for_each_safe(pos, temp, &msg->chunks) { 339 list_del_init(pos); 340 chunk = list_entry(pos, struct sctp_chunk, frag_list); 341 sctp_chunk_free(chunk); 342 } 343 sctp_datamsg_put(msg); 344 return ERR_PTR(err); 345 } 346 347 /* Check whether this message has expired. */ 348 int sctp_chunk_abandoned(struct sctp_chunk *chunk) 349 { 350 struct sctp_datamsg *msg = chunk->msg; 351 352 if (!msg->can_abandon) 353 return 0; 354 355 if (time_after(jiffies, msg->expires_at)) 356 return 1; 357 358 return 0; 359 } 360 361 /* This chunk (and consequently entire message) has failed in its sending. */ 362 void sctp_chunk_fail(struct sctp_chunk *chunk, int error) 363 { 364 chunk->msg->send_failed = 1; 365 chunk->msg->send_error = error; 366 } 367