1// SPDX-License-Identifier: GPL-2.0-or-later
2/* SCTP kernel implementation
3 * (C) Copyright IBM Corp. 2003, 2004
4 *
5 * This file is part of the SCTP kernel implementation
6 *
7 * This file contains the code relating the chunk abstraction.
8 *
9 * Please send any bug reports or fixes you make to the
10 * email address(es):
11 *    lksctp developers <linux-sctp@vger.kernel.org>
12 *
13 * Written or modified by:
14 *    Jon Grimm             <jgrimm@us.ibm.com>
15 *    Sridhar Samudrala     <sri@us.ibm.com>
16 */
17
18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19
20#include <linux/types.h>
21#include <linux/kernel.h>
22#include <linux/net.h>
23#include <linux/inet.h>
24#include <linux/skbuff.h>
25#include <linux/slab.h>
26#include <net/sock.h>
27#include <net/sctp/sctp.h>
28#include <net/sctp/sm.h>
29
30/* This file is mostly in anticipation of future work, but initially
31 * populate with fragment tracking for an outbound message.
32 */
33
34/* Initialize datamsg from memory. */
35static void sctp_datamsg_init(struct sctp_datamsg *msg)
36{
37	refcount_set(&msg->refcnt, 1);
38	msg->send_failed = 0;
39	msg->send_error = 0;
40	msg->can_delay = 1;
41	msg->abandoned = 0;
42	msg->expires_at = 0;
43	INIT_LIST_HEAD(&msg->chunks);
44}
45
46/* Allocate and initialize datamsg. */
47static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
48{
49	struct sctp_datamsg *msg;
50	msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
51	if (msg) {
52		sctp_datamsg_init(msg);
53		SCTP_DBG_OBJCNT_INC(datamsg);
54	}
55	return msg;
56}
57
58void sctp_datamsg_free(struct sctp_datamsg *msg)
59{
60	struct sctp_chunk *chunk;
61
62	/* This doesn't have to be a _safe vairant because
63	 * sctp_chunk_free() only drops the refs.
64	 */
65	list_for_each_entry(chunk, &msg->chunks, frag_list)
66		sctp_chunk_free(chunk);
67
68	sctp_datamsg_put(msg);
69}
70
71/* Final destructruction of datamsg memory. */
72static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
73{
74	struct sctp_association *asoc = NULL;
75	struct list_head *pos, *temp;
76	struct sctp_chunk *chunk;
77	struct sctp_ulpevent *ev;
78	int error, sent;
79
80	/* Release all references. */
81	list_for_each_safe(pos, temp, &msg->chunks) {
82		list_del_init(pos);
83		chunk = list_entry(pos, struct sctp_chunk, frag_list);
84
85		if (!msg->send_failed) {
86			sctp_chunk_put(chunk);
87			continue;
88		}
89
90		asoc = chunk->asoc;
91		error = msg->send_error ?: asoc->outqueue.error;
92		sent = chunk->has_tsn ? SCTP_DATA_SENT : SCTP_DATA_UNSENT;
93
94		if (sctp_ulpevent_type_enabled(asoc->subscribe,
95					       SCTP_SEND_FAILED)) {
96			ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
97							    error, GFP_ATOMIC);
98			if (ev)
99				asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
100		}
101
102		if (sctp_ulpevent_type_enabled(asoc->subscribe,
103					       SCTP_SEND_FAILED_EVENT)) {
104			ev = sctp_ulpevent_make_send_failed_event(asoc, chunk,
105								  sent, error,
106								  GFP_ATOMIC);
107			if (ev)
108				asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
109		}
110
111		sctp_chunk_put(chunk);
112	}
113
114	SCTP_DBG_OBJCNT_DEC(datamsg);
115	kfree(msg);
116}
117
118/* Hold a reference. */
119static void sctp_datamsg_hold(struct sctp_datamsg *msg)
120{
121	refcount_inc(&msg->refcnt);
122}
123
124/* Release a reference. */
125void sctp_datamsg_put(struct sctp_datamsg *msg)
126{
127	if (refcount_dec_and_test(&msg->refcnt))
128		sctp_datamsg_destroy(msg);
129}
130
131/* Assign a chunk to this datamsg. */
132static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
133{
134	sctp_datamsg_hold(msg);
135	chunk->msg = msg;
136}
137
138
139/* A data chunk can have a maximum payload of (2^16 - 20).  Break
140 * down any such message into smaller chunks.  Opportunistically, fragment
141 * the chunks down to the current MTU constraints.  We may get refragmented
142 * later if the PMTU changes, but it is _much better_ to fragment immediately
143 * with a reasonable guess than always doing our fragmentation on the
144 * soft-interrupt.
145 */
146struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
147					    struct sctp_sndrcvinfo *sinfo,
148					    struct iov_iter *from)
149{
150	size_t len, first_len, max_data, remaining;
151	size_t msg_len = iov_iter_count(from);
152	struct sctp_shared_key *shkey = NULL;
153	struct list_head *pos, *temp;
154	struct sctp_chunk *chunk;
155	struct sctp_datamsg *msg;
156	int err;
157
158	msg = sctp_datamsg_new(GFP_KERNEL);
159	if (!msg)
160		return ERR_PTR(-ENOMEM);
161
162	/* Note: Calculate this outside of the loop, so that all fragments
163	 * have the same expiration.
164	 */
165	if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
166	    (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
167	     !SCTP_PR_POLICY(sinfo->sinfo_flags)))
168		msg->expires_at = jiffies +
169				  msecs_to_jiffies(sinfo->sinfo_timetolive);
170
171	/* This is the biggest possible DATA chunk that can fit into
172	 * the packet
173	 */
174	max_data = asoc->frag_point;
175	if (unlikely(!max_data)) {
176		max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk),
177					       sctp_datachk_len(&asoc->stream));
178		pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%zu)",
179				    __func__, asoc, max_data);
180	}
181
182	/* If the peer requested that we authenticate DATA chunks
183	 * we need to account for bundling of the AUTH chunks along with
184	 * DATA.
185	 */
186	if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
187		struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
188
189		if (hmac_desc)
190			max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +
191					      hmac_desc->hmac_len);
192
193		if (sinfo->sinfo_tsn &&
194		    sinfo->sinfo_ssn != asoc->active_key_id) {
195			shkey = sctp_auth_get_shkey(asoc, sinfo->sinfo_ssn);
196			if (!shkey) {
197				err = -EINVAL;
198				goto errout;
199			}
200		} else {
201			shkey = asoc->shkey;
202		}
203	}
204
205	/* Set first_len and then account for possible bundles on first frag */
206	first_len = max_data;
207
208	/* Check to see if we have a pending SACK and try to let it be bundled
209	 * with this message.  Do this if we don't have any data queued already.
210	 * To check that, look at out_qlen and retransmit list.
211	 * NOTE: we will not reduce to account for SACK, if the message would
212	 * not have been fragmented.
213	 */
214	if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
215	    asoc->outqueue.out_qlen == 0 &&
216	    list_empty(&asoc->outqueue.retransmit) &&
217	    msg_len > max_data)
218		first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk));
219
220	/* Encourage Cookie-ECHO bundling. */
221	if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
222		first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
223
224	/* Account for a different sized first fragment */
225	if (msg_len >= first_len) {
226		msg->can_delay = 0;
227		if (msg_len > first_len)
228			SCTP_INC_STATS(asoc->base.net,
229				       SCTP_MIB_FRAGUSRMSGS);
230	} else {
231		/* Which may be the only one... */
232		first_len = msg_len;
233	}
234
235	/* Create chunks for all DATA chunks. */
236	for (remaining = msg_len; remaining; remaining -= len) {
237		u8 frag = SCTP_DATA_MIDDLE_FRAG;
238
239		if (remaining == msg_len) {
240			/* First frag, which may also be the last */
241			frag |= SCTP_DATA_FIRST_FRAG;
242			len = first_len;
243		} else {
244			/* Middle frags */
245			len = max_data;
246		}
247
248		if (len >= remaining) {
249			/* Last frag, which may also be the first */
250			len = remaining;
251			frag |= SCTP_DATA_LAST_FRAG;
252
253			/* The application requests to set the I-bit of the
254			 * last DATA chunk of a user message when providing
255			 * the user message to the SCTP implementation.
256			 */
257			if ((sinfo->sinfo_flags & SCTP_EOF) ||
258			    (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
259				frag |= SCTP_DATA_SACK_IMM;
260		}
261
262		chunk = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag,
263						       GFP_KERNEL);
264		if (!chunk) {
265			err = -ENOMEM;
266			goto errout;
267		}
268
269		err = sctp_user_addto_chunk(chunk, len, from);
270		if (err < 0)
271			goto errout_chunk_free;
272
273		chunk->shkey = shkey;
274
275		/* Put the chunk->skb back into the form expected by send.  */
276		__skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr -
277				       chunk->skb->data);
278
279		sctp_datamsg_assign(msg, chunk);
280		list_add_tail(&chunk->frag_list, &msg->chunks);
281	}
282
283	return msg;
284
285errout_chunk_free:
286	sctp_chunk_free(chunk);
287
288errout:
289	list_for_each_safe(pos, temp, &msg->chunks) {
290		list_del_init(pos);
291		chunk = list_entry(pos, struct sctp_chunk, frag_list);
292		sctp_chunk_free(chunk);
293	}
294	sctp_datamsg_put(msg);
295
296	return ERR_PTR(err);
297}
298
299/* Check whether this message has expired. */
300int sctp_chunk_abandoned(struct sctp_chunk *chunk)
301{
302	if (!chunk->asoc->peer.prsctp_capable)
303		return 0;
304
305	if (chunk->msg->abandoned)
306		return 1;
307
308	if (!chunk->has_tsn &&
309	    !(chunk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG))
310		return 0;
311
312	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
313	    time_after(jiffies, chunk->msg->expires_at)) {
314		struct sctp_stream_out *streamout =
315			SCTP_SO(&chunk->asoc->stream,
316				chunk->sinfo.sinfo_stream);
317
318		if (chunk->sent_count) {
319			chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
320			streamout->ext->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
321		} else {
322			chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
323			streamout->ext->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
324		}
325		chunk->msg->abandoned = 1;
326		return 1;
327	} else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
328		   chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
329		struct sctp_stream_out *streamout =
330			SCTP_SO(&chunk->asoc->stream,
331				chunk->sinfo.sinfo_stream);
332
333		chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
334		streamout->ext->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
335		chunk->msg->abandoned = 1;
336		return 1;
337	} else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
338		   chunk->msg->expires_at &&
339		   time_after(jiffies, chunk->msg->expires_at)) {
340		chunk->msg->abandoned = 1;
341		return 1;
342	}
343	/* PRIO policy is processed by sendmsg, not here */
344
345	return 0;
346}
347
348/* This chunk (and consequently entire message) has failed in its sending. */
349void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
350{
351	chunk->msg->send_failed = 1;
352	chunk->msg->send_error = error;
353}
354