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, write to 28 * the Free Software Foundation, 59 Temple Place - Suite 330, 29 * Boston, MA 02111-1307, USA. 30 * 31 * Please send any bug reports or fixes you make to the 32 * email address(es): 33 * lksctp developers <linux-sctp@vger.kernel.org> 34 * 35 * Written or modified by: 36 * La Monte H.P. Yarroll <piggy@acm.org> 37 * Karl Knutson <karl@athena.chicago.il.us> 38 */ 39 40 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 41 42 #include <net/sctp/sctp.h> 43 #include <net/sctp/sm.h> 44 #include <linux/interrupt.h> 45 #include <linux/slab.h> 46 47 /* Initialize an SCTP inqueue. */ 48 void sctp_inq_init(struct sctp_inq *queue) 49 { 50 INIT_LIST_HEAD(&queue->in_chunk_list); 51 queue->in_progress = NULL; 52 53 /* Create a task for delivering data. */ 54 INIT_WORK(&queue->immediate, NULL); 55 } 56 57 /* Release the memory associated with an SCTP inqueue. */ 58 void sctp_inq_free(struct sctp_inq *queue) 59 { 60 struct sctp_chunk *chunk, *tmp; 61 62 /* Empty the queue. */ 63 list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) { 64 list_del_init(&chunk->list); 65 sctp_chunk_free(chunk); 66 } 67 68 /* If there is a packet which is currently being worked on, 69 * free it as well. 70 */ 71 if (queue->in_progress) { 72 sctp_chunk_free(queue->in_progress); 73 queue->in_progress = NULL; 74 } 75 } 76 77 /* Put a new packet in an SCTP inqueue. 78 * We assume that packet->sctp_hdr is set and in host byte order. 79 */ 80 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk) 81 { 82 /* Directly call the packet handling routine. */ 83 if (chunk->rcvr->dead) { 84 sctp_chunk_free(chunk); 85 return; 86 } 87 88 /* We are now calling this either from the soft interrupt 89 * or from the backlog processing. 90 * Eventually, we should clean up inqueue to not rely 91 * on the BH related data structures. 92 */ 93 list_add_tail(&chunk->list, &q->in_chunk_list); 94 if (chunk->asoc) 95 chunk->asoc->stats.ipackets++; 96 q->immediate.func(&q->immediate); 97 } 98 99 /* Peek at the next chunk on the inqeue. */ 100 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue) 101 { 102 struct sctp_chunk *chunk; 103 sctp_chunkhdr_t *ch = NULL; 104 105 chunk = queue->in_progress; 106 /* If there is no more chunks in this packet, say so */ 107 if (chunk->singleton || 108 chunk->end_of_packet || 109 chunk->pdiscard) 110 return NULL; 111 112 ch = (sctp_chunkhdr_t *)chunk->chunk_end; 113 114 return ch; 115 } 116 117 118 /* Extract a chunk from an SCTP inqueue. 119 * 120 * WARNING: If you need to put the chunk on another queue, you need to 121 * make a shallow copy (clone) of it. 122 */ 123 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue) 124 { 125 struct sctp_chunk *chunk; 126 sctp_chunkhdr_t *ch = NULL; 127 128 /* The assumption is that we are safe to process the chunks 129 * at this time. 130 */ 131 132 if ((chunk = queue->in_progress)) { 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 sctp_chunk_free(chunk); 140 chunk = queue->in_progress = NULL; 141 } else { 142 /* Nothing to do. Next chunk in the packet, please. */ 143 ch = (sctp_chunkhdr_t *) chunk->chunk_end; 144 145 /* Force chunk->skb->data to chunk->chunk_end. */ 146 skb_pull(chunk->skb, 147 chunk->chunk_end - chunk->skb->data); 148 149 /* Verify that we have at least chunk headers 150 * worth of buffer left. 151 */ 152 if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) { 153 sctp_chunk_free(chunk); 154 chunk = queue->in_progress = NULL; 155 } 156 } 157 } 158 159 /* Do we need to take the next packet out of the queue to process? */ 160 if (!chunk) { 161 struct list_head *entry; 162 163 /* Is the queue empty? */ 164 if (list_empty(&queue->in_chunk_list)) 165 return NULL; 166 167 entry = queue->in_chunk_list.next; 168 chunk = queue->in_progress = 169 list_entry(entry, struct sctp_chunk, list); 170 list_del_init(entry); 171 172 /* This is the first chunk in the packet. */ 173 chunk->singleton = 1; 174 ch = (sctp_chunkhdr_t *) chunk->skb->data; 175 chunk->data_accepted = 0; 176 } 177 178 chunk->chunk_hdr = ch; 179 chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); 180 /* In the unlikely case of an IP reassembly, the skb could be 181 * non-linear. If so, update chunk_end so that it doesn't go past 182 * the skb->tail. 183 */ 184 if (unlikely(skb_is_nonlinear(chunk->skb))) { 185 if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) 186 chunk->chunk_end = skb_tail_pointer(chunk->skb); 187 } 188 skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t)); 189 chunk->subh.v = NULL; /* Subheader is no longer valid. */ 190 191 if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) { 192 /* This is not a singleton */ 193 chunk->singleton = 0; 194 } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) { 195 /* RFC 2960, Section 6.10 Bundling 196 * 197 * Partial chunks MUST NOT be placed in an SCTP packet. 198 * If the receiver detects a partial chunk, it MUST drop 199 * the chunk. 200 * 201 * Since the end of the chunk is past the end of our buffer 202 * (which contains the whole packet, we can freely discard 203 * the whole packet. 204 */ 205 sctp_chunk_free(chunk); 206 chunk = queue->in_progress = NULL; 207 208 return NULL; 209 } else { 210 /* We are at the end of the packet, so mark the chunk 211 * in case we need to send a SACK. 212 */ 213 chunk->end_of_packet = 1; 214 } 215 216 pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n", 217 chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)), 218 ntohs(chunk->chunk_hdr->length), chunk->skb->len); 219 220 return chunk; 221 } 222 223 /* Set a top-half handler. 224 * 225 * Originally, we the top-half handler was scheduled as a BH. We now 226 * call the handler directly in sctp_inq_push() at a time that 227 * we know we are lock safe. 228 * The intent is that this routine will pull stuff out of the 229 * inqueue and process it. 230 */ 231 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback) 232 { 233 INIT_WORK(&q->immediate, callback); 234 } 235