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_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_USER(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, 0);
 264
 265                 if (!chunk) {
 266                         err = -ENOMEM;
 267                         goto errout;
 268                 }
 269
 270                 err = sctp_user_addto_chunk(chunk, len, from);
 271                 if (err < 0)
 272                         goto errout_chunk_free;
 273
 274                 /* Put the chunk->skb back into the form expected by send.  */
 275                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 276                            - (__u8 *)chunk->skb->data);
 277
 278                 sctp_datamsg_assign(msg, chunk);
 279                 list_add_tail(&chunk->frag_list, &msg->chunks);
 280
 281                 /* The first chunk, the first chunk was likely short
 282                  * to allow bundling, so reset to full size.
 283                  */
 284                 if (0 == i)
 285                         len = max;
 286         }
 287
 288         /* .. now the leftover bytes. */
 289         if (over) {
 290                 if (!whole)
 291                         frag = SCTP_DATA_NOT_FRAG;
 292                 else
 293                         frag = SCTP_DATA_LAST_FRAG;
 294
 295                 if ((sinfo->sinfo_flags & SCTP_EOF) ||
 296                     (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 297                         frag |= SCTP_DATA_SACK_IMM;
 298
 299                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 300
 301                 if (!chunk) {
 302                         err = -ENOMEM;
 303                         goto errout;
 304                 }
 305
 306                 err = sctp_user_addto_chunk(chunk, over, from);
 307
 308                 /* Put the chunk->skb back into the form expected by send.  */
 309                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 310                            - (__u8 *)chunk->skb->data);
 311                 if (err < 0)
 312                         goto errout_chunk_free;
 313
 314                 sctp_datamsg_assign(msg, chunk);
 315                 list_add_tail(&chunk->frag_list, &msg->chunks);
 316         }
 317
 318         return msg;
 319
 320 errout_chunk_free:
 321         sctp_chunk_free(chunk);
 322
 323 errout:
 324         list_for_each_safe(pos, temp, &msg->chunks) {
 325                 list_del_init(pos);
 326                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 327                 sctp_chunk_free(chunk);
 328         }
 329         sctp_datamsg_put(msg);
 330         return ERR_PTR(err);
 331 }
 332
 333 /* Check whether this message has expired. */
 334 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 335 {
 336         struct sctp_datamsg *msg = chunk->msg;
 337
 338         if (!msg->can_abandon)
 339                 return 0;
 340
 341         if (time_after(jiffies, msg->expires_at))
 342                 return 1;
 343
 344         return 0;
 345 }
 346
 347 /* This chunk (and consequently entire message) has failed in its sending. */
 348 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 349 {
 350         chunk->msg->send_failed = 1;
 351         chunk->msg->send_error = error;
 352 }