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, write to
  22  * the Free Software Foundation, 59 Temple Place - Suite 330,
  23  * Boston, MA 02111-1307, USA.
  24  *
  25  * Please send any bug reports or fixes you make to the
  26  * email address(es):
  27  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  28  *
  29  * Or submit a bug report through the following website:
  30  *    http://www.sf.net/projects/lksctp
  31  *
  32  * Written or modified by:
  33  *    Jon Grimm             <jgrimm@us.ibm.com>
  34  *    Sridhar Samudrala     <sri@us.ibm.com>
  35  *
  36  * Any bugs reported given to us we will try to fix... any fixes shared will
  37  * be incorporated into the next SCTP release.
  38  */
  39
  40 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  41
  42 #include <linux/types.h>
  43 #include <linux/kernel.h>
  44 #include <linux/net.h>
  45 #include <linux/inet.h>
  46 #include <linux/skbuff.h>
  47 #include <linux/slab.h>
  48 #include <net/sock.h>
  49 #include <net/sctp/sctp.h>
  50 #include <net/sctp/sm.h>
  51
  52 /* This file is mostly in anticipation of future work, but initially
  53  * populate with fragment tracking for an outbound message.
  54  */
  55
  56 /* Initialize datamsg from memory. */
  57 static void sctp_datamsg_init(struct sctp_datamsg *msg)
  58 {
  59         atomic_set(&msg->refcnt, 1);
  60         msg->send_failed = 0;
  61         msg->send_error = 0;
  62         msg->can_abandon = 0;
  63         msg->can_delay = 1;
  64         msg->expires_at = 0;
  65         INIT_LIST_HEAD(&msg->chunks);
  66 }
  67
  68 /* Allocate and initialize datamsg. */
  69 SCTP_STATIC struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  70 {
  71         struct sctp_datamsg *msg;
  72         msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  73         if (msg) {
  74                 sctp_datamsg_init(msg);
  75                 SCTP_DBG_OBJCNT_INC(datamsg);
  76         }
  77         return msg;
  78 }
  79
  80 void sctp_datamsg_free(struct sctp_datamsg *msg)
  81 {
  82         struct sctp_chunk *chunk;
  83
  84         /* This doesn't have to be a _safe vairant because
  85          * sctp_chunk_free() only drops the refs.
  86          */
  87         list_for_each_entry(chunk, &msg->chunks, frag_list)
  88                 sctp_chunk_free(chunk);
  89
  90         sctp_datamsg_put(msg);
  91 }
  92
  93 /* Final destructruction of datamsg memory. */
  94 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  95 {
  96         struct list_head *pos, *temp;
  97         struct sctp_chunk *chunk;
  98         struct sctp_sock *sp;
  99         struct sctp_ulpevent *ev;
 100         struct sctp_association *asoc = NULL;
 101         int error = 0, notify;
 102
 103         /* If we failed, we may need to notify. */
 104         notify = msg->send_failed ? -1 : 0;
 105
 106         /* Release all references. */
 107         list_for_each_safe(pos, temp, &msg->chunks) {
 108                 list_del_init(pos);
 109                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 110                 /* Check whether we _really_ need to notify. */
 111                 if (notify < 0) {
 112                         asoc = chunk->asoc;
 113                         if (msg->send_error)
 114                                 error = msg->send_error;
 115                         else
 116                                 error = asoc->outqueue.error;
 117
 118                         sp = sctp_sk(asoc->base.sk);
 119                         notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 120                                                             &sp->subscribe);
 121                 }
 122
 123                 /* Generate a SEND FAILED event only if enabled. */
 124                 if (notify > 0) {
 125                         int sent;
 126                         if (chunk->has_tsn)
 127                                 sent = SCTP_DATA_SENT;
 128                         else
 129                                 sent = SCTP_DATA_UNSENT;
 130
 131                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 132                                                             error, GFP_ATOMIC);
 133                         if (ev)
 134                                 sctp_ulpq_tail_event(&asoc->ulpq, ev);
 135                 }
 136
 137                 sctp_chunk_put(chunk);
 138         }
 139
 140         SCTP_DBG_OBJCNT_DEC(datamsg);
 141         kfree(msg);
 142 }
 143
 144 /* Hold a reference. */
 145 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 146 {
 147         atomic_inc(&msg->refcnt);
 148 }
 149
 150 /* Release a reference. */
 151 void sctp_datamsg_put(struct sctp_datamsg *msg)
 152 {
 153         if (atomic_dec_and_test(&msg->refcnt))
 154                 sctp_datamsg_destroy(msg);
 155 }
 156
 157 /* Assign a chunk to this datamsg. */
 158 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 159 {
 160         sctp_datamsg_hold(msg);
 161         chunk->msg = msg;
 162 }
 163
 164
 165 /* A data chunk can have a maximum payload of (2^16 - 20).  Break
 166  * down any such message into smaller chunks.  Opportunistically, fragment
 167  * the chunks down to the current MTU constraints.  We may get refragmented
 168  * later if the PMTU changes, but it is _much better_ to fragment immediately
 169  * with a reasonable guess than always doing our fragmentation on the
 170  * soft-interrupt.
 171  */
 172 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 173                                             struct sctp_sndrcvinfo *sinfo,
 174                                             struct msghdr *msgh, int msg_len)
 175 {
 176         int max, whole, i, offset, over, err;
 177         int len, first_len;
 178         int max_data;
 179         struct sctp_chunk *chunk;
 180         struct sctp_datamsg *msg;
 181         struct list_head *pos, *temp;
 182         __u8 frag;
 183
 184         msg = sctp_datamsg_new(GFP_KERNEL);
 185         if (!msg)
 186                 return ERR_PTR(-ENOMEM);
 187
 188         /* Note: Calculate this outside of the loop, so that all fragments
 189          * have the same expiration.
 190          */
 191         if (sinfo->sinfo_timetolive) {
 192                 /* sinfo_timetolive is in milliseconds */
 193                 msg->expires_at = jiffies +
 194                                     msecs_to_jiffies(sinfo->sinfo_timetolive);
 195                 msg->can_abandon = 1;
 196                 SCTP_DEBUG_PRINTK("%s: msg:%p expires_at: %ld jiffies:%ld\n",
 197                                   __func__, msg, msg->expires_at, jiffies);
 198         }
 199
 200         /* This is the biggest possible DATA chunk that can fit into
 201          * the packet
 202          */
 203         max_data = asoc->pathmtu -
 204                 sctp_sk(asoc->base.sk)->pf->af->net_header_len -
 205                 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk);
 206
 207         max = asoc->frag_point;
 208         /* If the the peer requested that we authenticate DATA chunks
 209          * we need to accound for bundling of the AUTH chunks along with
 210          * DATA.
 211          */
 212         if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 213                 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 214
 215                 if (hmac_desc)
 216                         max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
 217                                             hmac_desc->hmac_len);
 218         }
 219
 220         /* Now, check if we need to reduce our max */
 221         if (max > max_data)
 222                 max = max_data;
 223
 224         whole = 0;
 225         first_len = max;
 226
 227         /* Check to see if we have a pending SACK and try to let it be bundled
 228          * with this message.  Do this if we don't have any data queued already.
 229          * To check that, look at out_qlen and retransmit list.
 230          * NOTE: we will not reduce to account for SACK, if the message would
 231          * not have been fragmented.
 232          */
 233         if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
 234             asoc->outqueue.out_qlen == 0 &&
 235             list_empty(&asoc->outqueue.retransmit) &&
 236             msg_len > max)
 237                 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t));
 238
 239         /* Encourage Cookie-ECHO bundling. */
 240         if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 241                 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 242
 243         /* Now that we adjusted completely, reset first_len */
 244         if (first_len > max_data)
 245                 first_len = max_data;
 246
 247         /* Account for a different sized first fragment */
 248         if (msg_len >= first_len) {
 249                 msg_len -= first_len;
 250                 whole = 1;
 251                 msg->can_delay = 0;
 252         }
 253
 254         /* How many full sized?  How many bytes leftover? */
 255         whole += msg_len / max;
 256         over = msg_len % max;
 257         offset = 0;
 258
 259         if ((whole > 1) || (whole && over))
 260                 SCTP_INC_STATS_USER(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS);
 261
 262         /* Create chunks for all the full sized DATA chunks. */
 263         for (i=0, len=first_len; i < whole; i++) {
 264                 frag = SCTP_DATA_MIDDLE_FRAG;
 265
 266                 if (0 == i)
 267                         frag |= SCTP_DATA_FIRST_FRAG;
 268
 269                 if ((i == (whole - 1)) && !over) {
 270                         frag |= SCTP_DATA_LAST_FRAG;
 271
 272                         /* The application requests to set the I-bit of the
 273                          * last DATA chunk of a user message when providing
 274                          * the user message to the SCTP implementation.
 275                          */
 276                         if ((sinfo->sinfo_flags & SCTP_EOF) ||
 277                             (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 278                                 frag |= SCTP_DATA_SACK_IMM;
 279                 }
 280
 281                 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 282
 283                 if (!chunk) {
 284                         err = -ENOMEM;
 285                         goto errout;
 286                 }
 287
 288                 err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 289                 if (err < 0)
 290                         goto errout_chunk_free;
 291
 292                 offset += len;
 293
 294                 /* Put the chunk->skb back into the form expected by send.  */
 295                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 296                            - (__u8 *)chunk->skb->data);
 297
 298                 sctp_datamsg_assign(msg, chunk);
 299                 list_add_tail(&chunk->frag_list, &msg->chunks);
 300
 301                 /* The first chunk, the first chunk was likely short
 302                  * to allow bundling, so reset to full size.
 303                  */
 304                 if (0 == i)
 305                         len = max;
 306         }
 307
 308         /* .. now the leftover bytes. */
 309         if (over) {
 310                 if (!whole)
 311                         frag = SCTP_DATA_NOT_FRAG;
 312                 else
 313                         frag = SCTP_DATA_LAST_FRAG;
 314
 315                 if ((sinfo->sinfo_flags & SCTP_EOF) ||
 316                     (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 317                         frag |= SCTP_DATA_SACK_IMM;
 318
 319                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 320
 321                 if (!chunk) {
 322                         err = -ENOMEM;
 323                         goto errout;
 324                 }
 325
 326                 err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 327
 328                 /* Put the chunk->skb back into the form expected by send.  */
 329                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 330                            - (__u8 *)chunk->skb->data);
 331                 if (err < 0)
 332                         goto errout_chunk_free;
 333
 334                 sctp_datamsg_assign(msg, chunk);
 335                 list_add_tail(&chunk->frag_list, &msg->chunks);
 336         }
 337
 338         return msg;
 339
 340 errout_chunk_free:
 341         sctp_chunk_free(chunk);
 342
 343 errout:
 344         list_for_each_safe(pos, temp, &msg->chunks) {
 345                 list_del_init(pos);
 346                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 347                 sctp_chunk_free(chunk);
 348         }
 349         sctp_datamsg_put(msg);
 350         return ERR_PTR(err);
 351 }
 352
 353 /* Check whether this message has expired. */
 354 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 355 {
 356         struct sctp_datamsg *msg = chunk->msg;
 357
 358         if (!msg->can_abandon)
 359                 return 0;
 360
 361         if (time_after(jiffies, msg->expires_at))
 362                 return 1;
 363
 364         return 0;
 365 }
 366
 367 /* This chunk (and consequently entire message) has failed in its sending. */
 368 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 369 {
 370         chunk->msg->send_failed = 1;
 371         chunk->msg->send_error = error;
 372 }