net/sctp/chunk.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* SCTP kernel implementation
   3  * (C) Copyright IBM Corp. 2003, 2004
   4  *
   5  * This file is part of the SCTP kernel implementation
   6  *
   7  * This file contains the code relating the chunk abstraction.
   8  *
   9  * Please send any bug reports or fixes you make to the
  10  * email address(es):
  11  *    lksctp developers <linux-sctp@vger.kernel.org>
  12  *
  13  * Written or modified by:
  14  *    Jon Grimm             <jgrimm@us.ibm.com>
  15  *    Sridhar Samudrala     <sri@us.ibm.com>
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/types.h>
  21 #include <linux/kernel.h>
  22 #include <linux/net.h>
  23 #include <linux/inet.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/slab.h>
  26 #include <net/sock.h>
  27 #include <net/sctp/sctp.h>
  28 #include <net/sctp/sm.h>
  29
  30 /* This file is mostly in anticipation of future work, but initially
  31  * populate with fragment tracking for an outbound message.
  32  */
  33
  34 /* Initialize datamsg from memory. */
  35 static void sctp_datamsg_init(struct sctp_datamsg *msg)
  36 {
  37         refcount_set(&msg->refcnt, 1);
  38         msg->send_failed = 0;
  39         msg->send_error = 0;
  40         msg->can_delay = 1;
  41         msg->abandoned = 0;
  42         msg->expires_at = 0;
  43         INIT_LIST_HEAD(&msg->chunks);
  44 }
  45
  46 /* Allocate and initialize datamsg. */
  47 static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  48 {
  49         struct sctp_datamsg *msg;
  50         msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  51         if (msg) {
  52                 sctp_datamsg_init(msg);
  53                 SCTP_DBG_OBJCNT_INC(datamsg);
  54         }
  55         return msg;
  56 }
  57
  58 void sctp_datamsg_free(struct sctp_datamsg *msg)
  59 {
  60         struct sctp_chunk *chunk;
  61
  62         /* This doesn't have to be a _safe vairant because
  63          * sctp_chunk_free() only drops the refs.
  64          */
  65         list_for_each_entry(chunk, &msg->chunks, frag_list)
  66                 sctp_chunk_free(chunk);
  67
  68         sctp_datamsg_put(msg);
  69 }
  70
  71 /* Final destructruction of datamsg memory. */
  72 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  73 {
  74         struct sctp_association *asoc = NULL;
  75         struct list_head *pos, *temp;
  76         struct sctp_chunk *chunk;
  77         struct sctp_ulpevent *ev;
  78         int error, sent;
  79
  80         /* Release all references. */
  81         list_for_each_safe(pos, temp, &msg->chunks) {
  82                 list_del_init(pos);
  83                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
  84
  85                 if (!msg->send_failed) {
  86                         sctp_chunk_put(chunk);
  87                         continue;
  88                 }
  89
  90                 asoc = chunk->asoc;
  91                 error = msg->send_error ?: asoc->outqueue.error;
  92                 sent = chunk->has_tsn ? SCTP_DATA_SENT : SCTP_DATA_UNSENT;
  93
  94                 if (sctp_ulpevent_type_enabled(asoc->subscribe,
  95                                                SCTP_SEND_FAILED)) {
  96                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
  97                                                             error, GFP_ATOMIC);
  98                         if (ev)
  99                                 asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
 100                 }
 101
 102                 if (sctp_ulpevent_type_enabled(asoc->subscribe,
 103                                                SCTP_SEND_FAILED_EVENT)) {
 104                         ev = sctp_ulpevent_make_send_failed_event(asoc, chunk,
 105                                                                   sent, error,
 106                                                                   GFP_ATOMIC);
 107                         if (ev)
 108                                 asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
 109                 }
 110
 111                 sctp_chunk_put(chunk);
 112         }
 113
 114         SCTP_DBG_OBJCNT_DEC(datamsg);
 115         kfree(msg);
 116 }
 117
 118 /* Hold a reference. */
 119 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 120 {
 121         refcount_inc(&msg->refcnt);
 122 }
 123
 124 /* Release a reference. */
 125 void sctp_datamsg_put(struct sctp_datamsg *msg)
 126 {
 127         if (refcount_dec_and_test(&msg->refcnt))
 128                 sctp_datamsg_destroy(msg);
 129 }
 130
 131 /* Assign a chunk to this datamsg. */
 132 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 133 {
 134         sctp_datamsg_hold(msg);
 135         chunk->msg = msg;
 136 }
 137
 138
 139 /* A data chunk can have a maximum payload of (2^16 - 20).  Break
 140  * down any such message into smaller chunks.  Opportunistically, fragment
 141  * the chunks down to the current MTU constraints.  We may get refragmented
 142  * later if the PMTU changes, but it is _much better_ to fragment immediately
 143  * with a reasonable guess than always doing our fragmentation on the
 144  * soft-interrupt.
 145  */
 146 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 147                                             struct sctp_sndrcvinfo *sinfo,
 148                                             struct iov_iter *from)
 149 {
 150         size_t len, first_len, max_data, remaining;
 151         size_t msg_len = iov_iter_count(from);
 152         struct sctp_shared_key *shkey = NULL;
 153         struct list_head *pos, *temp;
 154         struct sctp_chunk *chunk;
 155         struct sctp_datamsg *msg;
 156         int err;
 157
 158         msg = sctp_datamsg_new(GFP_KERNEL);
 159         if (!msg)
 160                 return ERR_PTR(-ENOMEM);
 161
 162         /* Note: Calculate this outside of the loop, so that all fragments
 163          * have the same expiration.
 164          */
 165         if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
 166             (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
 167              !SCTP_PR_POLICY(sinfo->sinfo_flags)))
 168                 msg->expires_at = jiffies +
 169                                   msecs_to_jiffies(sinfo->sinfo_timetolive);
 170
 171         /* This is the biggest possible DATA chunk that can fit into
 172          * the packet
 173          */
 174         max_data = asoc->frag_point;
 175         if (unlikely(!max_data)) {
 176                 max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk),
 177                                                sctp_datachk_len(&asoc->stream));
 178                 pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%zu)",
 179                                     __func__, asoc, max_data);
 180         }
 181
 182         /* If the peer requested that we authenticate DATA chunks
 183          * we need to account for bundling of the AUTH chunks along with
 184          * DATA.
 185          */
 186         if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 187                 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 188
 189                 if (hmac_desc)
 190                         max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +
 191                                               hmac_desc->hmac_len);
 192
 193                 if (sinfo->sinfo_tsn &&
 194                     sinfo->sinfo_ssn != asoc->active_key_id) {
 195                         shkey = sctp_auth_get_shkey(asoc, sinfo->sinfo_ssn);
 196                         if (!shkey) {
 197                                 err = -EINVAL;
 198                                 goto errout;
 199                         }
 200                 } else {
 201                         shkey = asoc->shkey;
 202                 }
 203         }
 204
 205         /* Set first_len and then account for possible bundles on first frag */
 206         first_len = max_data;
 207
 208         /* Check to see if we have a pending SACK and try to let it be bundled
 209          * with this message.  Do this if we don't have any data queued already.
 210          * To check that, look at out_qlen and retransmit list.
 211          * NOTE: we will not reduce to account for SACK, if the message would
 212          * not have been fragmented.
 213          */
 214         if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
 215             asoc->outqueue.out_qlen == 0 &&
 216             list_empty(&asoc->outqueue.retransmit) &&
 217             msg_len > max_data)
 218                 first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk));
 219
 220         /* Encourage Cookie-ECHO bundling. */
 221         if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 222                 first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 223
 224         /* Account for a different sized first fragment */
 225         if (msg_len >= first_len) {
 226                 msg->can_delay = 0;
 227                 if (msg_len > first_len)
 228                         SCTP_INC_STATS(asoc->base.net,
 229                                        SCTP_MIB_FRAGUSRMSGS);
 230         } else {
 231                 /* Which may be the only one... */
 232                 first_len = msg_len;
 233         }
 234
 235         /* Create chunks for all DATA chunks. */
 236         for (remaining = msg_len; remaining; remaining -= len) {
 237                 u8 frag = SCTP_DATA_MIDDLE_FRAG;
 238
 239                 if (remaining == msg_len) {
 240                         /* First frag, which may also be the last */
 241                         frag |= SCTP_DATA_FIRST_FRAG;
 242                         len = first_len;
 243                 } else {
 244                         /* Middle frags */
 245                         len = max_data;
 246                 }
 247
 248                 if (len >= remaining) {
 249                         /* Last frag, which may also be the first */
 250                         len = remaining;
 251                         frag |= SCTP_DATA_LAST_FRAG;
 252
 253                         /* The application requests to set the I-bit of the
 254                          * last DATA chunk of a user message when providing
 255                          * the user message to the SCTP implementation.
 256                          */
 257                         if ((sinfo->sinfo_flags & SCTP_EOF) ||
 258                             (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 259                                 frag |= SCTP_DATA_SACK_IMM;
 260                 }
 261
 262                 chunk = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag,
 263                                                        GFP_KERNEL);
 264                 if (!chunk) {
 265                         err = -ENOMEM;
 266                         goto errout;
 267                 }
 268
 269                 err = sctp_user_addto_chunk(chunk, len, from);
 270                 if (err < 0)
 271                         goto errout_chunk_free;
 272
 273                 chunk->shkey = shkey;
 274
 275                 /* Put the chunk->skb back into the form expected by send.  */
 276                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr -
 277                                        chunk->skb->data);
 278
 279                 sctp_datamsg_assign(msg, chunk);
 280                 list_add_tail(&chunk->frag_list, &msg->chunks);
 281         }
 282
 283         return msg;
 284
 285 errout_chunk_free:
 286         sctp_chunk_free(chunk);
 287
 288 errout:
 289         list_for_each_safe(pos, temp, &msg->chunks) {
 290                 list_del_init(pos);
 291                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 292                 sctp_chunk_free(chunk);
 293         }
 294         sctp_datamsg_put(msg);
 295
 296         return ERR_PTR(err);
 297 }
 298
 299 /* Check whether this message has expired. */
 300 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 301 {
 302         if (!chunk->asoc->peer.prsctp_capable)
 303                 return 0;
 304
 305         if (chunk->msg->abandoned)
 306                 return 1;
 307
 308         if (!chunk->has_tsn &&
 309             !(chunk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG))
 310                 return 0;
 311
 312         if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
 313             time_after(jiffies, chunk->msg->expires_at)) {
 314                 struct sctp_stream_out *streamout =
 315                         SCTP_SO(&chunk->asoc->stream,
 316                                 chunk->sinfo.sinfo_stream);
 317
 318                 if (chunk->sent_count) {
 319                         chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 320                         streamout->ext->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 321                 } else {
 322                         chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 323                         streamout->ext->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 324                 }
 325                 chunk->msg->abandoned = 1;
 326                 return 1;
 327         } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
 328                    chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
 329                 struct sctp_stream_out *streamout =
 330                         SCTP_SO(&chunk->asoc->stream,
 331                                 chunk->sinfo.sinfo_stream);
 332
 333                 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 334                 streamout->ext->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 335                 chunk->msg->abandoned = 1;
 336                 return 1;
 337         } else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
 338                    chunk->msg->expires_at &&
 339                    time_after(jiffies, chunk->msg->expires_at)) {
 340                 chunk->msg->abandoned = 1;
 341                 return 1;
 342         }
 343         /* PRIO policy is processed by sendmsg, not here */
 344
 345         return 0;
 346 }
 347
 348 /* This chunk (and consequently entire message) has failed in its sending. */
 349 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 350 {
 351         chunk->msg->send_failed = 1;
 352         chunk->msg->send_error = error;
 353 }