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 <linux-sctp@vger.kernel.org>
  28  *
  29  * Written or modified by:
  30  *    Jon Grimm             <jgrimm@us.ibm.com>
  31  *    Sridhar Samudrala     <sri@us.ibm.com>
  32  */
  33
  34 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/types.h>
  37 #include <linux/kernel.h>
  38 #include <linux/net.h>
  39 #include <linux/inet.h>
  40 #include <linux/skbuff.h>
  41 #include <linux/slab.h>
  42 #include <net/sock.h>
  43 #include <net/sctp/sctp.h>
  44 #include <net/sctp/sm.h>
  45
  46 /* This file is mostly in anticipation of future work, but initially
  47  * populate with fragment tracking for an outbound message.
  48  */
  49
  50 /* Initialize datamsg from memory. */
  51 static void sctp_datamsg_init(struct sctp_datamsg *msg)
  52 {
  53         atomic_set(&msg->refcnt, 1);
  54         msg->send_failed = 0;
  55         msg->send_error = 0;
  56         msg->can_abandon = 0;
  57         msg->can_delay = 1;
  58         msg->expires_at = 0;
  59         INIT_LIST_HEAD(&msg->chunks);
  60 }
  61
  62 /* Allocate and initialize datamsg. */
  63 static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  64 {
  65         struct sctp_datamsg *msg;
  66         msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  67         if (msg) {
  68                 sctp_datamsg_init(msg);
  69                 SCTP_DBG_OBJCNT_INC(datamsg);
  70         }
  71         return msg;
  72 }
  73
  74 void sctp_datamsg_free(struct sctp_datamsg *msg)
  75 {
  76         struct sctp_chunk *chunk;
  77
  78         /* This doesn't have to be a _safe vairant because
  79          * sctp_chunk_free() only drops the refs.
  80          */
  81         list_for_each_entry(chunk, &msg->chunks, frag_list)
  82                 sctp_chunk_free(chunk);
  83
  84         sctp_datamsg_put(msg);
  85 }
  86
  87 /* Final destructruction of datamsg memory. */
  88 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  89 {
  90         struct list_head *pos, *temp;
  91         struct sctp_chunk *chunk;
  92         struct sctp_sock *sp;
  93         struct sctp_ulpevent *ev;
  94         struct sctp_association *asoc = NULL;
  95         int error = 0, notify;
  96
  97         /* If we failed, we may need to notify. */
  98         notify = msg->send_failed ? -1 : 0;
  99
 100         /* Release all references. */
 101         list_for_each_safe(pos, temp, &msg->chunks) {
 102                 list_del_init(pos);
 103                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 104                 /* Check whether we _really_ need to notify. */
 105                 if (notify < 0) {
 106                         asoc = chunk->asoc;
 107                         if (msg->send_error)
 108                                 error = msg->send_error;
 109                         else
 110                                 error = asoc->outqueue.error;
 111
 112                         sp = sctp_sk(asoc->base.sk);
 113                         notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 114                                                             &sp->subscribe);
 115                 }
 116
 117                 /* Generate a SEND FAILED event only if enabled. */
 118                 if (notify > 0) {
 119                         int sent;
 120                         if (chunk->has_tsn)
 121                                 sent = SCTP_DATA_SENT;
 122                         else
 123                                 sent = SCTP_DATA_UNSENT;
 124
 125                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 126                                                             error, GFP_ATOMIC);
 127                         if (ev)
 128                                 sctp_ulpq_tail_event(&asoc->ulpq, ev);
 129                 }
 130
 131                 sctp_chunk_put(chunk);
 132         }
 133
 134         SCTP_DBG_OBJCNT_DEC(datamsg);
 135         kfree(msg);
 136 }
 137
 138 /* Hold a reference. */
 139 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 140 {
 141         atomic_inc(&msg->refcnt);
 142 }
 143
 144 /* Release a reference. */
 145 void sctp_datamsg_put(struct sctp_datamsg *msg)
 146 {
 147         if (atomic_dec_and_test(&msg->refcnt))
 148                 sctp_datamsg_destroy(msg);
 149 }
 150
 151 /* Assign a chunk to this datamsg. */
 152 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 153 {
 154         sctp_datamsg_hold(msg);
 155         chunk->msg = msg;
 156 }
 157
 158
 159 /* A data chunk can have a maximum payload of (2^16 - 20).  Break
 160  * down any such message into smaller chunks.  Opportunistically, fragment
 161  * the chunks down to the current MTU constraints.  We may get refragmented
 162  * later if the PMTU changes, but it is _much better_ to fragment immediately
 163  * with a reasonable guess than always doing our fragmentation on the
 164  * soft-interrupt.
 165  */
 166 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 167                                             struct sctp_sndrcvinfo *sinfo,
 168                                             struct msghdr *msgh, int msg_len)
 169 {
 170         int max, whole, i, offset, over, err;
 171         int len, first_len;
 172         int max_data;
 173         struct sctp_chunk *chunk;
 174         struct sctp_datamsg *msg;
 175         struct list_head *pos, *temp;
 176         __u8 frag;
 177
 178         msg = sctp_datamsg_new(GFP_KERNEL);
 179         if (!msg)
 180                 return ERR_PTR(-ENOMEM);
 181
 182         /* Note: Calculate this outside of the loop, so that all fragments
 183          * have the same expiration.
 184          */
 185         if (sinfo->sinfo_timetolive) {
 186                 /* sinfo_timetolive is in milliseconds */
 187                 msg->expires_at = jiffies +
 188                                     msecs_to_jiffies(sinfo->sinfo_timetolive);
 189                 msg->can_abandon = 1;
 190
 191                 pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__,
 192                          msg, msg->expires_at, jiffies);
 193         }
 194
 195         /* This is the biggest possible DATA chunk that can fit into
 196          * the packet
 197          */
 198         max_data = (asoc->pathmtu -
 199                 sctp_sk(asoc->base.sk)->pf->af->net_header_len -
 200                 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk)) & ~3;
 201
 202         max = asoc->frag_point;
 203         /* If the the peer requested that we authenticate DATA chunks
 204          * we need to accound for bundling of the AUTH chunks along with
 205          * DATA.
 206          */
 207         if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 208                 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 209
 210                 if (hmac_desc)
 211                         max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
 212                                             hmac_desc->hmac_len);
 213         }
 214
 215         /* Now, check if we need to reduce our max */
 216         if (max > max_data)
 217                 max = max_data;
 218
 219         whole = 0;
 220         first_len = max;
 221
 222         /* Check to see if we have a pending SACK and try to let it be bundled
 223          * with this message.  Do this if we don't have any data queued already.
 224          * To check that, look at out_qlen and retransmit list.
 225          * NOTE: we will not reduce to account for SACK, if the message would
 226          * not have been fragmented.
 227          */
 228         if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
 229             asoc->outqueue.out_qlen == 0 &&
 230             list_empty(&asoc->outqueue.retransmit) &&
 231             msg_len > max)
 232                 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t));
 233
 234         /* Encourage Cookie-ECHO bundling. */
 235         if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 236                 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 237
 238         /* Now that we adjusted completely, reset first_len */
 239         if (first_len > max_data)
 240                 first_len = max_data;
 241
 242         /* Account for a different sized first fragment */
 243         if (msg_len >= first_len) {
 244                 msg_len -= first_len;
 245                 whole = 1;
 246                 msg->can_delay = 0;
 247         }
 248
 249         /* How many full sized?  How many bytes leftover? */
 250         whole += msg_len / max;
 251         over = msg_len % max;
 252         offset = 0;
 253
 254         if ((whole > 1) || (whole && over))
 255                 SCTP_INC_STATS_USER(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS);
 256
 257         /* Create chunks for all the full sized DATA chunks. */
 258         for (i=0, len=first_len; i < whole; i++) {
 259                 frag = SCTP_DATA_MIDDLE_FRAG;
 260
 261                 if (0 == i)
 262                         frag |= SCTP_DATA_FIRST_FRAG;
 263
 264                 if ((i == (whole - 1)) && !over) {
 265                         frag |= SCTP_DATA_LAST_FRAG;
 266
 267                         /* The application requests to set the I-bit of the
 268                          * last DATA chunk of a user message when providing
 269                          * the user message to the SCTP implementation.
 270                          */
 271                         if ((sinfo->sinfo_flags & SCTP_EOF) ||
 272                             (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 273                                 frag |= SCTP_DATA_SACK_IMM;
 274                 }
 275
 276                 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 277
 278                 if (!chunk) {
 279                         err = -ENOMEM;
 280                         goto errout;
 281                 }
 282
 283                 err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 284                 if (err < 0)
 285                         goto errout_chunk_free;
 286
 287                 offset += len;
 288
 289                 /* Put the chunk->skb back into the form expected by send.  */
 290                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 291                            - (__u8 *)chunk->skb->data);
 292
 293                 sctp_datamsg_assign(msg, chunk);
 294                 list_add_tail(&chunk->frag_list, &msg->chunks);
 295
 296                 /* The first chunk, the first chunk was likely short
 297                  * to allow bundling, so reset to full size.
 298                  */
 299                 if (0 == i)
 300                         len = max;
 301         }
 302
 303         /* .. now the leftover bytes. */
 304         if (over) {
 305                 if (!whole)
 306                         frag = SCTP_DATA_NOT_FRAG;
 307                 else
 308                         frag = SCTP_DATA_LAST_FRAG;
 309
 310                 if ((sinfo->sinfo_flags & SCTP_EOF) ||
 311                     (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 312                         frag |= SCTP_DATA_SACK_IMM;
 313
 314                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 315
 316                 if (!chunk) {
 317                         err = -ENOMEM;
 318                         goto errout;
 319                 }
 320
 321                 err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 322
 323                 /* Put the chunk->skb back into the form expected by send.  */
 324                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 325                            - (__u8 *)chunk->skb->data);
 326                 if (err < 0)
 327                         goto errout_chunk_free;
 328
 329                 sctp_datamsg_assign(msg, chunk);
 330                 list_add_tail(&chunk->frag_list, &msg->chunks);
 331         }
 332
 333         return msg;
 334
 335 errout_chunk_free:
 336         sctp_chunk_free(chunk);
 337
 338 errout:
 339         list_for_each_safe(pos, temp, &msg->chunks) {
 340                 list_del_init(pos);
 341                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 342                 sctp_chunk_free(chunk);
 343         }
 344         sctp_datamsg_put(msg);
 345         return ERR_PTR(err);
 346 }
 347
 348 /* Check whether this message has expired. */
 349 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 350 {
 351         struct sctp_datamsg *msg = chunk->msg;
 352
 353         if (!msg->can_abandon)
 354                 return 0;
 355
 356         if (time_after(jiffies, msg->expires_at))
 357                 return 1;
 358
 359         return 0;
 360 }
 361
 362 /* This chunk (and consequently entire message) has failed in its sending. */
 363 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 364 {
 365         chunk->msg->send_failed = 1;
 366         chunk->msg->send_error = error;
 367 }