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 }