net/sctp/inqueue.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* SCTP kernel implementation
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2002 International Business Machines, Corp.
   6  *
   7  * This file is part of the SCTP kernel implementation
   8  *
   9  * These functions are the methods for accessing the SCTP inqueue.
  10  *
  11  * An SCTP inqueue is a queue into which you push SCTP packets
  12  * (which might be bundles or fragments of chunks) and out of which you
  13  * pop SCTP whole chunks.
  14  *
  15  * Please send any bug reports or fixes you make to the
  16  * email address(es):
  17  *    lksctp developers <linux-sctp@vger.kernel.org>
  18  *
  19  * Written or modified by:
  20  *    La Monte H.P. Yarroll <piggy@acm.org>
  21  *    Karl Knutson <karl@athena.chicago.il.us>
  22  */
  23
  24 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  25
  26 #include <net/sctp/sctp.h>
  27 #include <net/sctp/sm.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/slab.h>
  30
  31 /* Initialize an SCTP inqueue.  */
  32 void sctp_inq_init(struct sctp_inq *queue)
  33 {
  34         INIT_LIST_HEAD(&queue->in_chunk_list);
  35         queue->in_progress = NULL;
  36
  37         /* Create a task for delivering data.  */
  38         INIT_WORK(&queue->immediate, NULL);
  39 }
  40
  41 /* Release the memory associated with an SCTP inqueue.  */
  42 void sctp_inq_free(struct sctp_inq *queue)
  43 {
  44         struct sctp_chunk *chunk, *tmp;
  45
  46         /* Empty the queue.  */
  47         list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  48                 list_del_init(&chunk->list);
  49                 sctp_chunk_free(chunk);
  50         }
  51
  52         /* If there is a packet which is currently being worked on,
  53          * free it as well.
  54          */
  55         if (queue->in_progress) {
  56                 sctp_chunk_free(queue->in_progress);
  57                 queue->in_progress = NULL;
  58         }
  59 }
  60
  61 /* Put a new packet in an SCTP inqueue.
  62  * We assume that packet->sctp_hdr is set and in host byte order.
  63  */
  64 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  65 {
  66         /* Directly call the packet handling routine. */
  67         if (chunk->rcvr->dead) {
  68                 sctp_chunk_free(chunk);
  69                 return;
  70         }
  71
  72         /* We are now calling this either from the soft interrupt
  73          * or from the backlog processing.
  74          * Eventually, we should clean up inqueue to not rely
  75          * on the BH related data structures.
  76          */
  77         list_add_tail(&chunk->list, &q->in_chunk_list);
  78         if (chunk->asoc)
  79                 chunk->asoc->stats.ipackets++;
  80         q->immediate.func(&q->immediate);
  81 }
  82
  83 /* Peek at the next chunk on the inqeue. */
  84 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
  85 {
  86         struct sctp_chunk *chunk;
  87         struct sctp_chunkhdr *ch = NULL;
  88
  89         chunk = queue->in_progress;
  90         /* If there is no more chunks in this packet, say so */
  91         if (chunk->singleton ||
  92             chunk->end_of_packet ||
  93             chunk->pdiscard)
  94                     return NULL;
  95
  96         ch = (struct sctp_chunkhdr *)chunk->chunk_end;
  97
  98         return ch;
  99 }
 100
 101
 102 /* Extract a chunk from an SCTP inqueue.
 103  *
 104  * WARNING:  If you need to put the chunk on another queue, you need to
 105  * make a shallow copy (clone) of it.
 106  */
 107 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 108 {
 109         struct sctp_chunk *chunk;
 110         struct sctp_chunkhdr *ch = NULL;
 111
 112         /* The assumption is that we are safe to process the chunks
 113          * at this time.
 114          */
 115
 116         chunk = queue->in_progress;
 117         if (chunk) {
 118                 /* There is a packet that we have been working on.
 119                  * Any post processing work to do before we move on?
 120                  */
 121                 if (chunk->singleton ||
 122                     chunk->end_of_packet ||
 123                     chunk->pdiscard) {
 124                         if (chunk->head_skb == chunk->skb) {
 125                                 chunk->skb = skb_shinfo(chunk->skb)->frag_list;
 126                                 goto new_skb;
 127                         }
 128                         if (chunk->skb->next) {
 129                                 chunk->skb = chunk->skb->next;
 130                                 goto new_skb;
 131                         }
 132
 133                         if (chunk->head_skb)
 134                                 chunk->skb = chunk->head_skb;
 135                         sctp_chunk_free(chunk);
 136                         chunk = queue->in_progress = NULL;
 137                 } else {
 138                         /* Nothing to do. Next chunk in the packet, please. */
 139                         ch = (struct sctp_chunkhdr *)chunk->chunk_end;
 140                         /* Force chunk->skb->data to chunk->chunk_end.  */
 141                         skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
 142                         /* We are guaranteed to pull a SCTP header. */
 143                 }
 144         }
 145
 146         /* Do we need to take the next packet out of the queue to process? */
 147         if (!chunk) {
 148                 struct list_head *entry;
 149
 150 next_chunk:
 151                 /* Is the queue empty?  */
 152                 entry = sctp_list_dequeue(&queue->in_chunk_list);
 153                 if (!entry)
 154                         return NULL;
 155
 156                 chunk = list_entry(entry, struct sctp_chunk, list);
 157
 158                 if (skb_is_gso(chunk->skb) && skb_is_gso_sctp(chunk->skb)) {
 159                         /* GSO-marked skbs but without frags, handle
 160                          * them normally
 161                          */
 162                         if (skb_shinfo(chunk->skb)->frag_list)
 163                                 chunk->head_skb = chunk->skb;
 164
 165                         /* skbs with "cover letter" */
 166                         if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len)
 167                                 chunk->skb = skb_shinfo(chunk->skb)->frag_list;
 168
 169                         if (WARN_ON(!chunk->skb)) {
 170                                 __SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS);
 171                                 sctp_chunk_free(chunk);
 172                                 goto next_chunk;
 173                         }
 174                 }
 175
 176                 if (chunk->asoc)
 177                         sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb);
 178
 179                 queue->in_progress = chunk;
 180
 181 new_skb:
 182                 /* This is the first chunk in the packet.  */
 183                 ch = (struct sctp_chunkhdr *)chunk->skb->data;
 184                 chunk->singleton = 1;
 185                 chunk->data_accepted = 0;
 186                 chunk->pdiscard = 0;
 187                 chunk->auth = 0;
 188                 chunk->has_asconf = 0;
 189                 chunk->end_of_packet = 0;
 190                 if (chunk->head_skb) {
 191                         struct sctp_input_cb
 192                                 *cb = SCTP_INPUT_CB(chunk->skb),
 193                                 *head_cb = SCTP_INPUT_CB(chunk->head_skb);
 194
 195                         cb->chunk = head_cb->chunk;
 196                         cb->af = head_cb->af;
 197                 }
 198         }
 199
 200         chunk->chunk_hdr = ch;
 201         chunk->chunk_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
 202         skb_pull(chunk->skb, sizeof(*ch));
 203         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 204
 205         if (chunk->chunk_end + sizeof(*ch) <= skb_tail_pointer(chunk->skb)) {
 206                 /* This is not a singleton */
 207                 chunk->singleton = 0;
 208         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 209                 /* Discard inside state machine. */
 210                 chunk->pdiscard = 1;
 211                 chunk->chunk_end = skb_tail_pointer(chunk->skb);
 212         } else {
 213                 /* We are at the end of the packet, so mark the chunk
 214                  * in case we need to send a SACK.
 215                  */
 216                 chunk->end_of_packet = 1;
 217         }
 218
 219         pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 220                  chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 221                  ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 222
 223         return chunk;
 224 }
 225
 226 /* Set a top-half handler.
 227  *
 228  * Originally, we the top-half handler was scheduled as a BH.  We now
 229  * call the handler directly in sctp_inq_push() at a time that
 230  * we know we are lock safe.
 231  * The intent is that this routine will pull stuff out of the
 232  * inqueue and process it.
 233  */
 234 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 235 {
 236         INIT_WORK(&q->immediate, callback);
 237 }