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         refcount_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         refcount_inc(&msg->refcnt);
 140 }
 141
 142 /* Release a reference. */
 143 void sctp_datamsg_put(struct sctp_datamsg *msg)
 144 {
 145         if (refcount_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         size_t len, first_len, max_data, remaining;
 169         size_t msg_len = iov_iter_count(from);
 170         struct list_head *pos, *temp;
 171         struct sctp_chunk *chunk;
 172         struct sctp_datamsg *msg;
 173         int err;
 174
 175         msg = sctp_datamsg_new(GFP_KERNEL);
 176         if (!msg)
 177                 return ERR_PTR(-ENOMEM);
 178
 179         /* Note: Calculate this outside of the loop, so that all fragments
 180          * have the same expiration.
 181          */
 182         if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
 183             (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
 184              !SCTP_PR_POLICY(sinfo->sinfo_flags)))
 185                 msg->expires_at = jiffies +
 186                                   msecs_to_jiffies(sinfo->sinfo_timetolive);
 187
 188         /* This is the biggest possible DATA chunk that can fit into
 189          * the packet
 190          */
 191         max_data = asoc->pathmtu -
 192                    sctp_sk(asoc->base.sk)->pf->af->net_header_len -
 193                    sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk);
 194         max_data = SCTP_TRUNC4(max_data);
 195
 196         /* If the the peer requested that we authenticate DATA chunks
 197          * we need to account for bundling of the AUTH chunks along with
 198          * DATA.
 199          */
 200         if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 201                 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 202
 203                 if (hmac_desc)
 204                         max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +
 205                                               hmac_desc->hmac_len);
 206         }
 207
 208         /* Check what's our max considering the above */
 209         max_data = min_t(size_t, max_data, asoc->frag_point);
 210
 211         /* Set first_len and then account for possible bundles on first frag */
 212         first_len = max_data;
 213
 214         /* Check to see if we have a pending SACK and try to let it be bundled
 215          * with this message.  Do this if we don't have any data queued already.
 216          * To check that, look at out_qlen and retransmit list.
 217          * NOTE: we will not reduce to account for SACK, if the message would
 218          * not have been fragmented.
 219          */
 220         if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
 221             asoc->outqueue.out_qlen == 0 &&
 222             list_empty(&asoc->outqueue.retransmit) &&
 223             msg_len > max_data)
 224                 first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk));
 225
 226         /* Encourage Cookie-ECHO bundling. */
 227         if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 228                 first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 229
 230         /* Account for a different sized first fragment */
 231         if (msg_len >= first_len) {
 232                 msg->can_delay = 0;
 233                 if (msg_len > first_len)
 234                         SCTP_INC_STATS(sock_net(asoc->base.sk),
 235                                        SCTP_MIB_FRAGUSRMSGS);
 236         } else {
 237                 /* Which may be the only one... */
 238                 first_len = msg_len;
 239         }
 240
 241         /* Create chunks for all DATA chunks. */
 242         for (remaining = msg_len; remaining; remaining -= len) {
 243                 u8 frag = SCTP_DATA_MIDDLE_FRAG;
 244
 245                 if (remaining == msg_len) {
 246                         /* First frag, which may also be the last */
 247                         frag |= SCTP_DATA_FIRST_FRAG;
 248                         len = first_len;
 249                 } else {
 250                         /* Middle frags */
 251                         len = max_data;
 252                 }
 253
 254                 if (len >= remaining) {
 255                         /* Last frag, which may also be the first */
 256                         len = remaining;
 257                         frag |= SCTP_DATA_LAST_FRAG;
 258
 259                         /* The application requests to set the I-bit of the
 260                          * last DATA chunk of a user message when providing
 261                          * the user message to the SCTP implementation.
 262                          */
 263                         if ((sinfo->sinfo_flags & SCTP_EOF) ||
 264                             (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 265                                 frag |= SCTP_DATA_SACK_IMM;
 266                 }
 267
 268                 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag,
 269                                                  0, GFP_KERNEL);
 270                 if (!chunk) {
 271                         err = -ENOMEM;
 272                         goto errout;
 273                 }
 274
 275                 err = sctp_user_addto_chunk(chunk, len, from);
 276                 if (err < 0)
 277                         goto errout_chunk_free;
 278
 279                 /* Put the chunk->skb back into the form expected by send.  */
 280                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr -
 281                                        chunk->skb->data);
 282
 283                 sctp_datamsg_assign(msg, chunk);
 284                 list_add_tail(&chunk->frag_list, &msg->chunks);
 285         }
 286
 287         return msg;
 288
 289 errout_chunk_free:
 290         sctp_chunk_free(chunk);
 291
 292 errout:
 293         list_for_each_safe(pos, temp, &msg->chunks) {
 294                 list_del_init(pos);
 295                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 296                 sctp_chunk_free(chunk);
 297         }
 298         sctp_datamsg_put(msg);
 299
 300         return ERR_PTR(err);
 301 }
 302
 303 /* Check whether this message has expired. */
 304 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 305 {
 306         if (!chunk->asoc->peer.prsctp_capable)
 307                 return 0;
 308
 309         if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
 310             time_after(jiffies, chunk->msg->expires_at)) {
 311                 struct sctp_stream_out *streamout =
 312                         &chunk->asoc->stream.out[chunk->sinfo.sinfo_stream];
 313
 314                 if (chunk->sent_count) {
 315                         chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 316                         streamout->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 317                 } else {
 318                         chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 319                         streamout->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 320                 }
 321                 return 1;
 322         } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
 323                    chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
 324                 struct sctp_stream_out *streamout =
 325                         &chunk->asoc->stream.out[chunk->sinfo.sinfo_stream];
 326
 327                 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 328                 streamout->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 329                 return 1;
 330         } else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
 331                    chunk->msg->expires_at &&
 332                    time_after(jiffies, chunk->msg->expires_at)) {
 333                 return 1;
 334         }
 335         /* PRIO policy is processed by sendmsg, not here */
 336
 337         return 0;
 338 }
 339
 340 /* This chunk (and consequently entire message) has failed in its sending. */
 341 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 342 {
 343         chunk->msg->send_failed = 1;
 344         chunk->msg->send_error = error;
 345 }