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->abandoned = 0;
  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                                 asoc->stream.si->enqueue_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         refcount_inc(&msg->refcnt);
 141 }
 142
 143 /* Release a reference. */
 144 void sctp_datamsg_put(struct sctp_datamsg *msg)
 145 {
 146         if (refcount_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         size_t len, first_len, max_data, remaining;
 170         size_t msg_len = iov_iter_count(from);
 171         struct sctp_shared_key *shkey = NULL;
 172         struct list_head *pos, *temp;
 173         struct sctp_chunk *chunk;
 174         struct sctp_datamsg *msg;
 175         int err;
 176
 177         msg = sctp_datamsg_new(GFP_KERNEL);
 178         if (!msg)
 179                 return ERR_PTR(-ENOMEM);
 180
 181         /* Note: Calculate this outside of the loop, so that all fragments
 182          * have the same expiration.
 183          */
 184         if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
 185             (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
 186              !SCTP_PR_POLICY(sinfo->sinfo_flags)))
 187                 msg->expires_at = jiffies +
 188                                   msecs_to_jiffies(sinfo->sinfo_timetolive);
 189
 190         /* This is the biggest possible DATA chunk that can fit into
 191          * the packet
 192          */
 193         max_data = asoc->frag_point;
 194         if (unlikely(!max_data)) {
 195                 max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk),
 196                                                sctp_datachk_len(&asoc->stream));
 197                 pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%Zu)",
 198                                     __func__, asoc, max_data);
 199         }
 200
 201         /* If the the peer requested that we authenticate DATA chunks
 202          * we need to account for bundling of the AUTH chunks along with
 203          * DATA.
 204          */
 205         if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 206                 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 207
 208                 if (hmac_desc)
 209                         max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +
 210                                               hmac_desc->hmac_len);
 211
 212                 if (sinfo->sinfo_tsn &&
 213                     sinfo->sinfo_ssn != asoc->active_key_id) {
 214                         shkey = sctp_auth_get_shkey(asoc, sinfo->sinfo_ssn);
 215                         if (!shkey) {
 216                                 err = -EINVAL;
 217                                 goto errout;
 218                         }
 219                 } else {
 220                         shkey = asoc->shkey;
 221                 }
 222         }
 223
 224         /* Set first_len and then account for possible bundles on first frag */
 225         first_len = max_data;
 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_data)
 237                 first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk));
 238
 239         /* Encourage Cookie-ECHO bundling. */
 240         if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 241                 first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 242
 243         /* Account for a different sized first fragment */
 244         if (msg_len >= first_len) {
 245                 msg->can_delay = 0;
 246                 if (msg_len > first_len)
 247                         SCTP_INC_STATS(sock_net(asoc->base.sk),
 248                                        SCTP_MIB_FRAGUSRMSGS);
 249         } else {
 250                 /* Which may be the only one... */
 251                 first_len = msg_len;
 252         }
 253
 254         /* Create chunks for all DATA chunks. */
 255         for (remaining = msg_len; remaining; remaining -= len) {
 256                 u8 frag = SCTP_DATA_MIDDLE_FRAG;
 257
 258                 if (remaining == msg_len) {
 259                         /* First frag, which may also be the last */
 260                         frag |= SCTP_DATA_FIRST_FRAG;
 261                         len = first_len;
 262                 } else {
 263                         /* Middle frags */
 264                         len = max_data;
 265                 }
 266
 267                 if (len >= remaining) {
 268                         /* Last frag, which may also be the first */
 269                         len = remaining;
 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 = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag,
 282                                                        GFP_KERNEL);
 283                 if (!chunk) {
 284                         err = -ENOMEM;
 285                         goto errout;
 286                 }
 287
 288                 err = sctp_user_addto_chunk(chunk, len, from);
 289                 if (err < 0)
 290                         goto errout_chunk_free;
 291
 292                 chunk->shkey = shkey;
 293
 294                 /* Put the chunk->skb back into the form expected by send.  */
 295                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr -
 296                                        chunk->skb->data);
 297
 298                 sctp_datamsg_assign(msg, chunk);
 299                 list_add_tail(&chunk->frag_list, &msg->chunks);
 300         }
 301
 302         return msg;
 303
 304 errout_chunk_free:
 305         sctp_chunk_free(chunk);
 306
 307 errout:
 308         list_for_each_safe(pos, temp, &msg->chunks) {
 309                 list_del_init(pos);
 310                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 311                 sctp_chunk_free(chunk);
 312         }
 313         sctp_datamsg_put(msg);
 314
 315         return ERR_PTR(err);
 316 }
 317
 318 /* Check whether this message has expired. */
 319 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 320 {
 321         if (!chunk->asoc->peer.prsctp_capable)
 322                 return 0;
 323
 324         if (chunk->msg->abandoned)
 325                 return 1;
 326
 327         if (!chunk->has_tsn &&
 328             !(chunk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG))
 329                 return 0;
 330
 331         if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
 332             time_after(jiffies, chunk->msg->expires_at)) {
 333                 struct sctp_stream_out *streamout =
 334                         SCTP_SO(&chunk->asoc->stream,
 335                                 chunk->sinfo.sinfo_stream);
 336
 337                 if (chunk->sent_count) {
 338                         chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 339                         streamout->ext->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 340                 } else {
 341                         chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 342                         streamout->ext->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 343                 }
 344                 chunk->msg->abandoned = 1;
 345                 return 1;
 346         } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
 347                    chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
 348                 struct sctp_stream_out *streamout =
 349                         SCTP_SO(&chunk->asoc->stream,
 350                                 chunk->sinfo.sinfo_stream);
 351
 352                 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 353                 streamout->ext->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 354                 chunk->msg->abandoned = 1;
 355                 return 1;
 356         } else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
 357                    chunk->msg->expires_at &&
 358                    time_after(jiffies, chunk->msg->expires_at)) {
 359                 chunk->msg->abandoned = 1;
 360                 return 1;
 361         }
 362         /* PRIO policy is processed by sendmsg, not here */
 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 }