net/sctp/chunk.c

   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 }