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 /* Properly release the chunk which is being worked on. */
  42 static inline void sctp_inq_chunk_free(struct sctp_chunk *chunk)
  43 {
  44         if (chunk->head_skb)
  45                 chunk->skb = chunk->head_skb;
  46         sctp_chunk_free(chunk);
  47 }
  48
  49 /* Release the memory associated with an SCTP inqueue.  */
  50 void sctp_inq_free(struct sctp_inq *queue)
  51 {
  52         struct sctp_chunk *chunk, *tmp;
  53
  54         /* Empty the queue.  */
  55         list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  56                 list_del_init(&chunk->list);
  57                 sctp_chunk_free(chunk);
  58         }
  59
  60         /* If there is a packet which is currently being worked on,
  61          * free it as well.
  62          */
  63         if (queue->in_progress) {
  64                 sctp_inq_chunk_free(queue->in_progress);
  65                 queue->in_progress = NULL;
  66         }
  67 }
  68
  69 /* Put a new packet in an SCTP inqueue.
  70  * We assume that packet->sctp_hdr is set and in host byte order.
  71  */
  72 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  73 {
  74         /* Directly call the packet handling routine. */
  75         if (chunk->rcvr->dead) {
  76                 sctp_chunk_free(chunk);
  77                 return;
  78         }
  79
  80         /* We are now calling this either from the soft interrupt
  81          * or from the backlog processing.
  82          * Eventually, we should clean up inqueue to not rely
  83          * on the BH related data structures.
  84          */
  85         list_add_tail(&chunk->list, &q->in_chunk_list);
  86         if (chunk->asoc)
  87                 chunk->asoc->stats.ipackets++;
  88         q->immediate.func(&q->immediate);
  89 }
  90
  91 /* Peek at the next chunk on the inqeue. */
  92 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
  93 {
  94         struct sctp_chunk *chunk;
  95         struct sctp_chunkhdr *ch = NULL;
  96
  97         chunk = queue->in_progress;
  98         /* If there is no more chunks in this packet, say so */
  99         if (chunk->singleton ||
 100             chunk->end_of_packet ||
 101             chunk->pdiscard)
 102                     return NULL;
 103
 104         ch = (struct sctp_chunkhdr *)chunk->chunk_end;
 105
 106         return ch;
 107 }
 108
 109
 110 /* Extract a chunk from an SCTP inqueue.
 111  *
 112  * WARNING:  If you need to put the chunk on another queue, you need to
 113  * make a shallow copy (clone) of it.
 114  */
 115 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 116 {
 117         struct sctp_chunk *chunk;
 118         struct sctp_chunkhdr *ch = NULL;
 119
 120         /* The assumption is that we are safe to process the chunks
 121          * at this time.
 122          */
 123
 124         chunk = queue->in_progress;
 125         if (chunk) {
 126                 /* There is a packet that we have been working on.
 127                  * Any post processing work to do before we move on?
 128                  */
 129                 if (chunk->singleton ||
 130                     chunk->end_of_packet ||
 131                     chunk->pdiscard) {
 132                         if (chunk->head_skb == chunk->skb) {
 133                                 chunk->skb = skb_shinfo(chunk->skb)->frag_list;
 134                                 goto new_skb;
 135                         }
 136                         if (chunk->skb->next) {
 137                                 chunk->skb = chunk->skb->next;
 138                                 goto new_skb;
 139                         }
 140
 141                         sctp_inq_chunk_free(chunk);
 142                         chunk = queue->in_progress = NULL;
 143                 } else {
 144                         /* Nothing to do. Next chunk in the packet, please. */
 145                         ch = (struct sctp_chunkhdr *)chunk->chunk_end;
 146                         /* Force chunk->skb->data to chunk->chunk_end.  */
 147                         skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
 148                         /* We are guaranteed to pull a SCTP header. */
 149                 }
 150         }
 151
 152         /* Do we need to take the next packet out of the queue to process? */
 153         if (!chunk) {
 154                 struct list_head *entry;
 155
 156 next_chunk:
 157                 /* Is the queue empty?  */
 158                 entry = sctp_list_dequeue(&queue->in_chunk_list);
 159                 if (!entry)
 160                         return NULL;
 161
 162                 chunk = list_entry(entry, struct sctp_chunk, list);
 163
 164                 if (skb_is_gso(chunk->skb) && skb_is_gso_sctp(chunk->skb)) {
 165                         /* GSO-marked skbs but without frags, handle
 166                          * them normally
 167                          */
 168                         if (skb_shinfo(chunk->skb)->frag_list)
 169                                 chunk->head_skb = chunk->skb;
 170
 171                         /* skbs with "cover letter" */
 172                         if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len)
 173                                 chunk->skb = skb_shinfo(chunk->skb)->frag_list;
 174
 175                         if (WARN_ON(!chunk->skb)) {
 176                                 __SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS);
 177                                 sctp_chunk_free(chunk);
 178                                 goto next_chunk;
 179                         }
 180                 }
 181
 182                 if (chunk->asoc)
 183                         sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb);
 184
 185                 queue->in_progress = chunk;
 186
 187 new_skb:
 188                 /* This is the first chunk in the packet.  */
 189                 ch = (struct sctp_chunkhdr *)chunk->skb->data;
 190                 chunk->singleton = 1;
 191                 chunk->data_accepted = 0;
 192                 chunk->pdiscard = 0;
 193                 chunk->auth = 0;
 194                 chunk->has_asconf = 0;
 195                 chunk->end_of_packet = 0;
 196                 if (chunk->head_skb) {
 197                         struct sctp_input_cb
 198                                 *cb = SCTP_INPUT_CB(chunk->skb),
 199                                 *head_cb = SCTP_INPUT_CB(chunk->head_skb);
 200
 201                         cb->chunk = head_cb->chunk;
 202                         cb->af = head_cb->af;
 203                 }
 204         }
 205
 206         chunk->chunk_hdr = ch;
 207         chunk->chunk_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
 208         skb_pull(chunk->skb, sizeof(*ch));
 209         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 210
 211         if (chunk->chunk_end + sizeof(*ch) <= skb_tail_pointer(chunk->skb)) {
 212                 /* This is not a singleton */
 213                 chunk->singleton = 0;
 214         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 215                 /* Discard inside state machine. */
 216                 chunk->pdiscard = 1;
 217                 chunk->chunk_end = skb_tail_pointer(chunk->skb);
 218         } else {
 219                 /* We are at the end of the packet, so mark the chunk
 220                  * in case we need to send a SACK.
 221                  */
 222                 chunk->end_of_packet = 1;
 223         }
 224
 225         pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 226                  chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 227                  ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 228
 229         return chunk;
 230 }
 231
 232 /* Set a top-half handler.
 233  *
 234  * Originally, we the top-half handler was scheduled as a BH.  We now
 235  * call the handler directly in sctp_inq_push() at a time that
 236  * we know we are lock safe.
 237  * The intent is that this routine will pull stuff out of the
 238  * inqueue and process it.
 239  */
 240 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 241 {
 242         INIT_WORK(&q->immediate, callback);
 243 }