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 void sctp_datamsg_free(struct sctp_datamsg *msg)
  74 {
  75         struct sctp_chunk *chunk;
  76
  77         /* This doesn't have to be a _safe vairant because
  78          * sctp_chunk_free() only drops the refs.
  79          */
  80         list_for_each_entry(chunk, &msg->chunks, frag_list)
  81                 sctp_chunk_free(chunk);
  82
  83         sctp_datamsg_put(msg);
  84 }
  85
  86 /* Final destructruction of datamsg memory. */
  87 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  88 {
  89         struct list_head *pos, *temp;
  90         struct sctp_chunk *chunk;
  91         struct sctp_sock *sp;
  92         struct sctp_ulpevent *ev;
  93         struct sctp_association *asoc = NULL;
  94         int error = 0, notify;
  95
  96         /* If we failed, we may need to notify. */
  97         notify = msg->send_failed ? -1 : 0;
  98
  99         /* Release all references. */
 100         list_for_each_safe(pos, temp, &msg->chunks) {
 101                 list_del_init(pos);
 102                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 103                 /* Check whether we _really_ need to notify. */
 104                 if (notify < 0) {
 105                         asoc = chunk->asoc;
 106                         if (msg->send_error)
 107                                 error = msg->send_error;
 108                         else
 109                                 error = asoc->outqueue.error;
 110
 111                         sp = sctp_sk(asoc->base.sk);
 112                         notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 113                                                             &sp->subscribe);
 114                 }
 115
 116                 /* Generate a SEND FAILED event only if enabled. */
 117                 if (notify > 0) {
 118                         int sent;
 119                         if (chunk->has_tsn)
 120                                 sent = SCTP_DATA_SENT;
 121                         else
 122                                 sent = SCTP_DATA_UNSENT;
 123
 124                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 125                                                             error, GFP_ATOMIC);
 126                         if (ev)
 127                                 sctp_ulpq_tail_event(&asoc->ulpq, ev);
 128                 }
 129
 130                 sctp_chunk_put(chunk);
 131         }
 132
 133         SCTP_DBG_OBJCNT_DEC(datamsg);
 134         kfree(msg);
 135 }
 136
 137 /* Hold a reference. */
 138 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 139 {
 140         atomic_inc(&msg->refcnt);
 141 }
 142
 143 /* Release a reference. */
 144 void sctp_datamsg_put(struct sctp_datamsg *msg)
 145 {
 146         if (atomic_dec_and_test(&msg->refcnt))
 147                 sctp_datamsg_destroy(msg);
 148 }
 149
 150 /* Assign a chunk to this datamsg. */
 151 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 152 {
 153         sctp_datamsg_hold(msg);
 154         chunk->msg = msg;
 155 }
 156
 157
 158 /* A data chunk can have a maximum payload of (2^16 - 20).  Break
 159  * down any such message into smaller chunks.  Opportunistically, fragment
 160  * the chunks down to the current MTU constraints.  We may get refragmented
 161  * later if the PMTU changes, but it is _much better_ to fragment immediately
 162  * with a reasonable guess than always doing our fragmentation on the
 163  * soft-interrupt.
 164  */
 165 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 166                                             struct sctp_sndrcvinfo *sinfo,
 167                                             struct iov_iter *from)
 168 {
 169         int max, whole, i, offset, over, err;
 170         int len, first_len;
 171         int max_data;
 172         struct sctp_chunk *chunk;
 173         struct sctp_datamsg *msg;
 174         struct list_head *pos, *temp;
 175         size_t msg_len = iov_iter_count(from);
 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 account 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, len, from);
 284                 if (err < 0)
 285                         goto errout_chunk_free;
 286
 287                 /* Put the chunk->skb back into the form expected by send.  */
 288                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 289                            - (__u8 *)chunk->skb->data);
 290
 291                 sctp_datamsg_assign(msg, chunk);
 292                 list_add_tail(&chunk->frag_list, &msg->chunks);
 293
 294                 /* The first chunk, the first chunk was likely short
 295                  * to allow bundling, so reset to full size.
 296                  */
 297                 if (0 == i)
 298                         len = max;
 299         }
 300
 301         /* .. now the leftover bytes. */
 302         if (over) {
 303                 if (!whole)
 304                         frag = SCTP_DATA_NOT_FRAG;
 305                 else
 306                         frag = SCTP_DATA_LAST_FRAG;
 307
 308                 if ((sinfo->sinfo_flags & SCTP_EOF) ||
 309                     (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 310                         frag |= SCTP_DATA_SACK_IMM;
 311
 312                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 313
 314                 if (!chunk) {
 315                         err = -ENOMEM;
 316                         goto errout;
 317                 }
 318
 319                 err = sctp_user_addto_chunk(chunk, over, from);
 320
 321                 /* Put the chunk->skb back into the form expected by send.  */
 322                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 323                            - (__u8 *)chunk->skb->data);
 324                 if (err < 0)
 325                         goto errout_chunk_free;
 326
 327                 sctp_datamsg_assign(msg, chunk);
 328                 list_add_tail(&chunk->frag_list, &msg->chunks);
 329         }
 330
 331         return msg;
 332
 333 errout_chunk_free:
 334         sctp_chunk_free(chunk);
 335
 336 errout:
 337         list_for_each_safe(pos, temp, &msg->chunks) {
 338                 list_del_init(pos);
 339                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 340                 sctp_chunk_free(chunk);
 341         }
 342         sctp_datamsg_put(msg);
 343         return ERR_PTR(err);
 344 }
 345
 346 /* Check whether this message has expired. */
 347 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 348 {
 349         struct sctp_datamsg *msg = chunk->msg;
 350
 351         if (!msg->can_abandon)
 352                 return 0;
 353
 354         if (time_after(jiffies, msg->expires_at))
 355                 return 1;
 356
 357         return 0;
 358 }
 359
 360 /* This chunk (and consequently entire message) has failed in its sending. */
 361 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 362 {
 363         chunk->msg->send_failed = 1;
 364         chunk->msg->send_error = error;
 365 }