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 /* Final destructruction of datamsg memory. */ 74 static void sctp_datamsg_destroy(struct sctp_datamsg *msg) 75 { 76 struct list_head *pos, *temp; 77 struct sctp_chunk *chunk; 78 struct sctp_sock *sp; 79 struct sctp_ulpevent *ev; 80 struct sctp_association *asoc = NULL; 81 int error = 0, notify; 82 83 /* If we failed, we may need to notify. */ 84 notify = msg->send_failed ? -1 : 0; 85 86 /* Release all references. */ 87 list_for_each_safe(pos, temp, &msg->chunks) { 88 list_del_init(pos); 89 chunk = list_entry(pos, struct sctp_chunk, frag_list); 90 /* Check whether we _really_ need to notify. */ 91 if (notify < 0) { 92 asoc = chunk->asoc; 93 if (msg->send_error) 94 error = msg->send_error; 95 else 96 error = asoc->outqueue.error; 97 98 sp = sctp_sk(asoc->base.sk); 99 notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED, 100 &sp->subscribe); 101 } 102 103 /* Generate a SEND FAILED event only if enabled. */ 104 if (notify > 0) { 105 int sent; 106 if (chunk->has_tsn) 107 sent = SCTP_DATA_SENT; 108 else 109 sent = SCTP_DATA_UNSENT; 110 111 ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent, 112 error, GFP_ATOMIC); 113 if (ev) 114 sctp_ulpq_tail_event(&asoc->ulpq, ev); 115 } 116 117 sctp_chunk_put(chunk); 118 } 119 120 SCTP_DBG_OBJCNT_DEC(datamsg); 121 kfree(msg); 122 } 123 124 /* Hold a reference. */ 125 static void sctp_datamsg_hold(struct sctp_datamsg *msg) 126 { 127 atomic_inc(&msg->refcnt); 128 } 129 130 /* Release a reference. */ 131 void sctp_datamsg_put(struct sctp_datamsg *msg) 132 { 133 if (atomic_dec_and_test(&msg->refcnt)) 134 sctp_datamsg_destroy(msg); 135 } 136 137 /* Assign a chunk to this datamsg. */ 138 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk) 139 { 140 sctp_datamsg_hold(msg); 141 chunk->msg = msg; 142 } 143 144 145 /* A data chunk can have a maximum payload of (2^16 - 20). Break 146 * down any such message into smaller chunks. Opportunistically, fragment 147 * the chunks down to the current MTU constraints. We may get refragmented 148 * later if the PMTU changes, but it is _much better_ to fragment immediately 149 * with a reasonable guess than always doing our fragmentation on the 150 * soft-interrupt. 151 */ 152 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 153 struct sctp_sndrcvinfo *sinfo, 154 struct iov_iter *from) 155 { 156 int max, whole, i, offset, over, err; 157 int len, first_len; 158 int max_data; 159 struct sctp_chunk *chunk; 160 struct sctp_datamsg *msg; 161 struct list_head *pos, *temp; 162 size_t msg_len = iov_iter_count(from); 163 __u8 frag; 164 165 msg = sctp_datamsg_new(GFP_KERNEL); 166 if (!msg) 167 return ERR_PTR(-ENOMEM); 168 169 /* Note: Calculate this outside of the loop, so that all fragments 170 * have the same expiration. 171 */ 172 if (sinfo->sinfo_timetolive) { 173 /* sinfo_timetolive is in milliseconds */ 174 msg->expires_at = jiffies + 175 msecs_to_jiffies(sinfo->sinfo_timetolive); 176 msg->can_abandon = 1; 177 178 pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__, 179 msg, msg->expires_at, jiffies); 180 } 181 182 /* This is the biggest possible DATA chunk that can fit into 183 * the packet 184 */ 185 max_data = (asoc->pathmtu - 186 sctp_sk(asoc->base.sk)->pf->af->net_header_len - 187 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk)) & ~3; 188 189 max = asoc->frag_point; 190 /* If the the peer requested that we authenticate DATA chunks 191 * we need to account for bundling of the AUTH chunks along with 192 * DATA. 193 */ 194 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) { 195 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc); 196 197 if (hmac_desc) 198 max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) + 199 hmac_desc->hmac_len); 200 } 201 202 /* Now, check if we need to reduce our max */ 203 if (max > max_data) 204 max = max_data; 205 206 whole = 0; 207 first_len = max; 208 209 /* Check to see if we have a pending SACK and try to let it be bundled 210 * with this message. Do this if we don't have any data queued already. 211 * To check that, look at out_qlen and retransmit list. 212 * NOTE: we will not reduce to account for SACK, if the message would 213 * not have been fragmented. 214 */ 215 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) && 216 asoc->outqueue.out_qlen == 0 && 217 list_empty(&asoc->outqueue.retransmit) && 218 msg_len > max) 219 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t)); 220 221 /* Encourage Cookie-ECHO bundling. */ 222 if (asoc->state < SCTP_STATE_COOKIE_ECHOED) 223 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN; 224 225 /* Now that we adjusted completely, reset first_len */ 226 if (first_len > max_data) 227 first_len = max_data; 228 229 /* Account for a different sized first fragment */ 230 if (msg_len >= first_len) { 231 msg_len -= first_len; 232 whole = 1; 233 msg->can_delay = 0; 234 } 235 236 /* How many full sized? How many bytes leftover? */ 237 whole += msg_len / max; 238 over = msg_len % max; 239 offset = 0; 240 241 if ((whole > 1) || (whole && over)) 242 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS); 243 244 /* Create chunks for all the full sized DATA chunks. */ 245 for (i = 0, len = first_len; i < whole; i++) { 246 frag = SCTP_DATA_MIDDLE_FRAG; 247 248 if (0 == i) 249 frag |= SCTP_DATA_FIRST_FRAG; 250 251 if ((i == (whole - 1)) && !over) { 252 frag |= SCTP_DATA_LAST_FRAG; 253 254 /* The application requests to set the I-bit of the 255 * last DATA chunk of a user message when providing 256 * the user message to the SCTP implementation. 257 */ 258 if ((sinfo->sinfo_flags & SCTP_EOF) || 259 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 260 frag |= SCTP_DATA_SACK_IMM; 261 } 262 263 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 264 0, GFP_KERNEL); 265 266 if (!chunk) { 267 err = -ENOMEM; 268 goto errout; 269 } 270 271 err = sctp_user_addto_chunk(chunk, len, from); 272 if (err < 0) 273 goto errout_chunk_free; 274 275 /* Put the chunk->skb back into the form expected by send. */ 276 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 277 - (__u8 *)chunk->skb->data); 278 279 sctp_datamsg_assign(msg, chunk); 280 list_add_tail(&chunk->frag_list, &msg->chunks); 281 282 /* The first chunk, the first chunk was likely short 283 * to allow bundling, so reset to full size. 284 */ 285 if (0 == i) 286 len = max; 287 } 288 289 /* .. now the leftover bytes. */ 290 if (over) { 291 if (!whole) 292 frag = SCTP_DATA_NOT_FRAG; 293 else 294 frag = SCTP_DATA_LAST_FRAG; 295 296 if ((sinfo->sinfo_flags & SCTP_EOF) || 297 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 298 frag |= SCTP_DATA_SACK_IMM; 299 300 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 301 0, GFP_KERNEL); 302 303 if (!chunk) { 304 err = -ENOMEM; 305 goto errout; 306 } 307 308 err = sctp_user_addto_chunk(chunk, over, from); 309 310 /* Put the chunk->skb back into the form expected by send. */ 311 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr 312 - (__u8 *)chunk->skb->data); 313 if (err < 0) 314 goto errout_chunk_free; 315 316 sctp_datamsg_assign(msg, chunk); 317 list_add_tail(&chunk->frag_list, &msg->chunks); 318 } 319 320 return msg; 321 322 errout_chunk_free: 323 sctp_chunk_free(chunk); 324 325 errout: 326 list_for_each_safe(pos, temp, &msg->chunks) { 327 list_del_init(pos); 328 chunk = list_entry(pos, struct sctp_chunk, frag_list); 329 sctp_chunk_free(chunk); 330 } 331 sctp_datamsg_put(msg); 332 return ERR_PTR(err); 333 } 334 335 /* Check whether this message has expired. */ 336 int sctp_chunk_abandoned(struct sctp_chunk *chunk) 337 { 338 struct sctp_datamsg *msg = chunk->msg; 339 340 if (!msg->can_abandon) 341 return 0; 342 343 if (time_after(jiffies, msg->expires_at)) 344 return 1; 345 346 return 0; 347 } 348 349 /* This chunk (and consequently entire message) has failed in its sending. */ 350 void sctp_chunk_fail(struct sctp_chunk *chunk, int error) 351 { 352 chunk->msg->send_failed = 1; 353 chunk->msg->send_error = error; 354 } 355