LXR linux/net/sctp/inqueue.c

   1/* SCTP kernel implementation
   2 * Copyright (c) 1999-2000 Cisco, Inc.
   3 * Copyright (c) 1999-2001 Motorola, Inc.
   4 * Copyright (c) 2002 International Business Machines, Corp.
   5 *
   6 * This file is part of the SCTP kernel implementation
   7 *
   8 * These functions are the methods for accessing the SCTP inqueue.
   9 *
  10 * An SCTP inqueue is a queue into which you push SCTP packets
  11 * (which might be bundles or fragments of chunks) and out of which you
  12 * pop SCTP whole chunks.
  13 *
  14 * This SCTP implementation is free software;
  15 * you can redistribute it and/or modify it under the terms of
  16 * the GNU General Public License as published by
  17 * the Free Software Foundation; either version 2, or (at your option)
  18 * any later version.
  19 *
  20 * This SCTP implementation is distributed in the hope that it
  21 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  22 *                 ************************
  23 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  24 * See the GNU General Public License for more details.
  25 *
  26 * You should have received a copy of the GNU General Public License
  27 * along with GNU CC; see the file COPYING.  If not, see
  28 * <http://www.gnu.org/licenses/>.
  29 *
  30 * Please send any bug reports or fixes you make to the
  31 * email address(es):
  32 *    lksctp developers <linux-sctp@vger.kernel.org>
  33 *
  34 * Written or modified by:
  35 *    La Monte H.P. Yarroll <piggy@acm.org>
  36 *    Karl Knutson <karl@athena.chicago.il.us>
  37 */
  38
  39#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  40
  41#include <net/sctp/sctp.h>
  42#include <net/sctp/sm.h>
  43#include <linux/interrupt.h>
  44#include <linux/slab.h>
  45
  46/* Initialize an SCTP inqueue.  */
  47void sctp_inq_init(struct sctp_inq *queue)
  48{
  49        INIT_LIST_HEAD(&queue->in_chunk_list);
  50        queue->in_progress = NULL;
  51
  52        /* Create a task for delivering data.  */
  53        INIT_WORK(&queue->immediate, NULL);
  54}
  55
  56/* Release the memory associated with an SCTP inqueue.  */
  57void sctp_inq_free(struct sctp_inq *queue)
  58{
  59        struct sctp_chunk *chunk, *tmp;
  60
  61        /* Empty the queue.  */
  62        list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  63                list_del_init(&chunk->list);
  64                sctp_chunk_free(chunk);
  65        }
  66
  67        /* If there is a packet which is currently being worked on,
  68         * free it as well.
  69         */
  70        if (queue->in_progress) {
  71                sctp_chunk_free(queue->in_progress);
  72                queue->in_progress = NULL;
  73        }
  74}
  75
  76/* Put a new packet in an SCTP inqueue.
  77 * We assume that packet->sctp_hdr is set and in host byte order.
  78 */
  79void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  80{
  81        /* Directly call the packet handling routine. */
  82        if (chunk->rcvr->dead) {
  83                sctp_chunk_free(chunk);
  84                return;
  85        }
  86
  87        /* We are now calling this either from the soft interrupt
  88         * or from the backlog processing.
  89         * Eventually, we should clean up inqueue to not rely
  90         * on the BH related data structures.
  91         */
  92        list_add_tail(&chunk->list, &q->in_chunk_list);
  93        if (chunk->asoc)
  94                chunk->asoc->stats.ipackets++;
  95        q->immediate.func(&q->immediate);
  96}
  97
  98/* Peek at the next chunk on the inqeue. */
  99struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 100{
 101        struct sctp_chunk *chunk;
 102        struct sctp_chunkhdr *ch = NULL;
 103
 104        chunk = queue->in_progress;
 105        /* If there is no more chunks in this packet, say so */
 106        if (chunk->singleton ||
 107            chunk->end_of_packet ||
 108            chunk->pdiscard)
 109                    return NULL;
 110
 111        ch = (struct sctp_chunkhdr *)chunk->chunk_end;
 112
 113        return ch;
 114}
 115
 116
 117/* Extract a chunk from an SCTP inqueue.
 118 *
 119 * WARNING:  If you need to put the chunk on another queue, you need to
 120 * make a shallow copy (clone) of it.
 121 */
 122struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 123{
 124        struct sctp_chunk *chunk;
 125        struct sctp_chunkhdr *ch = NULL;
 126
 127        /* The assumption is that we are safe to process the chunks
 128         * at this time.
 129         */
 130
 131        chunk = queue->in_progress;
 132        if (chunk) {
 133                /* There is a packet that we have been working on.
 134                 * Any post processing work to do before we move on?
 135                 */
 136                if (chunk->singleton ||
 137                    chunk->end_of_packet ||
 138                    chunk->pdiscard) {
 139                        if (chunk->head_skb == chunk->skb) {
 140                                chunk->skb = skb_shinfo(chunk->skb)->frag_list;
 141                                goto new_skb;
 142                        }
 143                        if (chunk->skb->next) {
 144                                chunk->skb = chunk->skb->next;
 145                                goto new_skb;
 146                        }
 147
 148                        if (chunk->head_skb)
 149                                chunk->skb = chunk->head_skb;
 150                        sctp_chunk_free(chunk);
 151                        chunk = queue->in_progress = NULL;
 152                } else {
 153                        /* Nothing to do. Next chunk in the packet, please. */
 154                        ch = (struct sctp_chunkhdr *)chunk->chunk_end;
 155                        /* Force chunk->skb->data to chunk->chunk_end.  */
 156                        skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
 157                        /* We are guaranteed to pull a SCTP header. */
 158                }
 159        }
 160
 161        /* Do we need to take the next packet out of the queue to process? */
 162        if (!chunk) {
 163                struct list_head *entry;
 164
 165next_chunk:
 166                /* Is the queue empty?  */
 167                entry = sctp_list_dequeue(&queue->in_chunk_list);
 168                if (!entry)
 169                        return NULL;
 170
 171                chunk = list_entry(entry, struct sctp_chunk, list);
 172
 173                if ((skb_shinfo(chunk->skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP) {
 174                        /* GSO-marked skbs but without frags, handle
 175                         * them normally
 176                         */
 177                        if (skb_shinfo(chunk->skb)->frag_list)
 178                                chunk->head_skb = chunk->skb;
 179
 180                        /* skbs with "cover letter" */
 181                        if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len)
 182                                chunk->skb = skb_shinfo(chunk->skb)->frag_list;
 183
 184                        if (WARN_ON(!chunk->skb)) {
 185                                __SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS);
 186                                sctp_chunk_free(chunk);
 187                                goto next_chunk;
 188                        }
 189                }
 190
 191                if (chunk->asoc)
 192                        sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb);
 193
 194                queue->in_progress = chunk;
 195
 196new_skb:
 197                /* This is the first chunk in the packet.  */
 198                ch = (struct sctp_chunkhdr *)chunk->skb->data;
 199                chunk->singleton = 1;
 200                chunk->data_accepted = 0;
 201                chunk->pdiscard = 0;
 202                chunk->auth = 0;
 203                chunk->has_asconf = 0;
 204                chunk->end_of_packet = 0;
 205                if (chunk->head_skb) {
 206                        struct sctp_input_cb
 207                                *cb = SCTP_INPUT_CB(chunk->skb),
 208                                *head_cb = SCTP_INPUT_CB(chunk->head_skb);
 209
 210                        cb->chunk = head_cb->chunk;
 211                        cb->af = head_cb->af;
 212                }
 213        }
 214
 215        chunk->chunk_hdr = ch;
 216        chunk->chunk_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
 217        skb_pull(chunk->skb, sizeof(*ch));
 218        chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 219
 220        if (chunk->chunk_end + sizeof(*ch) < skb_tail_pointer(chunk->skb)) {
 221                /* This is not a singleton */
 222                chunk->singleton = 0;
 223        } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 224                /* Discard inside state machine. */
 225                chunk->pdiscard = 1;
 226                chunk->chunk_end = skb_tail_pointer(chunk->skb);
 227        } else {
 228                /* We are at the end of the packet, so mark the chunk
 229                 * in case we need to send a SACK.
 230                 */
 231                chunk->end_of_packet = 1;
 232        }
 233
 234        pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 235                 chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 236                 ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 237
 238        return chunk;
 239}
 240
 241/* Set a top-half handler.
 242 *
 243 * Originally, we the top-half handler was scheduled as a BH.  We now
 244 * call the handler directly in sctp_inq_push() at a time that
 245 * we know we are lock safe.
 246 * The intent is that this routine will pull stuff out of the
 247 * inqueue and process it.
 248 */
 249void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 250{
 251        INIT_WORK(&q->immediate, callback);
 252}
 253