1/*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
30 */
31
32#include <sys/cdefs.h>
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34
35#include "opt_inet.h"
36#include "opt_inet6.h"
37#include "opt_tcpdebug.h"
38
39#include <sys/param.h>
40#include <sys/kernel.h>
41#include <sys/malloc.h>
42#include <sys/mbuf.h>
43#include <sys/socket.h>
44#include <sys/socketvar.h>
45#include <sys/sysctl.h>
46#include <sys/syslog.h>
47#include <sys/systm.h>
48
49#include <vm/uma.h>
50
51#include <net/if.h>
52#include <net/route.h>
53#include <net/vnet.h>
54
55#include <netinet/in.h>
56#include <netinet/in_pcb.h>
57#include <netinet/in_systm.h>
58#include <netinet/in_var.h>
59#include <netinet/ip.h>
60#include <netinet/ip_var.h>
61#include <netinet/ip_options.h>
62#include <netinet/ip6.h>
63#include <netinet6/in6_pcb.h>
64#include <netinet6/ip6_var.h>
65#include <netinet6/nd6.h>
66#include <netinet/tcp.h>
67#include <netinet/tcp_fsm.h>
68#include <netinet/tcp_seq.h>
69#include <netinet/tcp_timer.h>
70#include <netinet/tcp_var.h>
71#include <netinet6/tcp6_var.h>
72#include <netinet/tcpip.h>
73#ifdef TCPDEBUG
74#include <netinet/tcp_debug.h>
75#endif /* TCPDEBUG */
76
77static int tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS);
78static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS);
79
80SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
81 "TCP Segment Reassembly Queue");
82
83static VNET_DEFINE(int, tcp_reass_maxseg) = 0;
84#define V_tcp_reass_maxseg VNET(tcp_reass_maxseg)
85SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
86 &VNET_NAME(tcp_reass_maxseg), 0, &tcp_reass_sysctl_maxseg, "I",
87 "Global maximum number of TCP Segments in Reassembly Queue");
88
89static VNET_DEFINE(int, tcp_reass_qsize) = 0;
90#define V_tcp_reass_qsize VNET(tcp_reass_qsize)
91SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
92 &VNET_NAME(tcp_reass_qsize), 0, &tcp_reass_sysctl_qsize, "I",
93 "Global number of TCP Segments currently in Reassembly Queue");
94
95static VNET_DEFINE(int, tcp_reass_overflows) = 0;
96#define V_tcp_reass_overflows VNET(tcp_reass_overflows)
97SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
98 &VNET_NAME(tcp_reass_overflows), 0,
99 "Global number of TCP Segment Reassembly Queue Overflows");
100
101static VNET_DEFINE(uma_zone_t, tcp_reass_zone);
102#define V_tcp_reass_zone VNET(tcp_reass_zone)
103
104/* Initialize TCP reassembly queue */
105static void
106tcp_reass_zone_change(void *tag)
107{
108
109 V_tcp_reass_maxseg = nmbclusters / 16;
110 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
111}
112
113void
114tcp_reass_init(void)
115{
116
117 V_tcp_reass_maxseg = nmbclusters / 16;
118 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
119 &V_tcp_reass_maxseg);
120 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
121 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
122 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
123 EVENTHANDLER_REGISTER(nmbclusters_change,
124 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
125}
126
127#ifdef VIMAGE
128void
129tcp_reass_destroy(void)
130{
131
132 uma_zdestroy(V_tcp_reass_zone);
133}
134#endif
135
136void
137tcp_reass_flush(struct tcpcb *tp)
138{
139 struct tseg_qent *qe;
140
141 INP_WLOCK_ASSERT(tp->t_inpcb);
142
143 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) {
144 LIST_REMOVE(qe, tqe_q);
145 m_freem(qe->tqe_m);
146 uma_zfree(V_tcp_reass_zone, qe);
147 tp->t_segqlen--;
148 }
149
150 KASSERT((tp->t_segqlen == 0),
151 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
152 tp, tp->t_segqlen));
153}
154
155static int
156tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS)
157{
158 V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone);
159 return (sysctl_handle_int(oidp, arg1, arg2, req));
160}
161
162static int
163tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS)
164{
165 V_tcp_reass_qsize = uma_zone_get_cur(V_tcp_reass_zone);
166 return (sysctl_handle_int(oidp, arg1, arg2, req));
167}
168
169int
170tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
171{
172 struct tseg_qent *q;
173 struct tseg_qent *p = NULL;
174 struct tseg_qent *nq;
175 struct tseg_qent *te = NULL;
176 struct socket *so = tp->t_inpcb->inp_socket;
177 int flags;
178
179 INP_WLOCK_ASSERT(tp->t_inpcb);
180
181 /*
182 * XXX: tcp_reass() is rather inefficient with its data structures
183 * and should be rewritten (see NetBSD for optimizations).
184 */
185
186 /*
187 * Call with th==NULL after become established to
188 * force pre-ESTABLISHED data up to user socket.
189 */
190 if (th == NULL)
191 goto present;
192
193 /*
194 * Limit the number of segments that can be queued to reduce the
195 * potential for mbuf exhaustion. For best performance, we want to be
196 * able to queue a full window's worth of segments. The size of the
197 * socket receive buffer determines our advertised window and grows
198 * automatically when socket buffer autotuning is enabled. Use it as the
199 * basis for our queue limit.
200 * Always let the missing segment through which caused this queue.
201 * NB: Access to the socket buffer is left intentionally unlocked as we
202 * can tolerate stale information here.
203 *
204 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
205 * should work but causes packets to be dropped when they shouldn't.
206 * Investigate why and re-evaluate the below limit after the behaviour
207 * is understood.
208 */
209 if (th->th_seq != tp->rcv_nxt &&
210 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) {
211 V_tcp_reass_overflows++;
212 TCPSTAT_INC(tcps_rcvmemdrop);
213 m_freem(m);
214 *tlenp = 0;
215 return (0);
216 }
217
218 /*
219 * Allocate a new queue entry. If we can't, or hit the zone limit
220 * just drop the pkt.
221 */
222 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT);
223 if (te == NULL) {
224 TCPSTAT_INC(tcps_rcvmemdrop);
225 m_freem(m);
226 *tlenp = 0;
227 return (0);
228 }
229 tp->t_segqlen++;
230
231 /*
232 * Find a segment which begins after this one does.
233 */
234 LIST_FOREACH(q, &tp->t_segq, tqe_q) {
235 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
236 break;
237 p = q;
238 }
239
240 /*
241 * If there is a preceding segment, it may provide some of
242 * our data already. If so, drop the data from the incoming
243 * segment. If it provides all of our data, drop us.
244 */
245 if (p != NULL) {
246 int i;
247 /* conversion to int (in i) handles seq wraparound */
248 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
249 if (i > 0) {
250 if (i >= *tlenp) {
251 TCPSTAT_INC(tcps_rcvduppack);
252 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
253 m_freem(m);
254 uma_zfree(V_tcp_reass_zone, te);
255 tp->t_segqlen--;
256 /*
257 * Try to present any queued data
258 * at the left window edge to the user.
259 * This is needed after the 3-WHS
260 * completes.
261 */
262 goto present; /* ??? */
263 }
264 m_adj(m, i);
265 *tlenp -= i;
266 th->th_seq += i;
267 }
268 }
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270 TCPSTAT_INC(tcps_rcvoopack);
271 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
272
273 /*
274 * While we overlap succeeding segments trim them or,
275 * if they are completely covered, dequeue them.
276 */
277 while (q) {
278 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
279 if (i <= 0)
280 break;
281 if (i < q->tqe_len) {
282 q->tqe_th->th_seq += i;
283 q->tqe_len -= i;
284 m_adj(q->tqe_m, i);
285 break;
286 }
287
288 nq = LIST_NEXT(q, tqe_q);
289 LIST_REMOVE(q, tqe_q);
290 m_freem(q->tqe_m);
291 uma_zfree(V_tcp_reass_zone, q);
292 tp->t_segqlen--;
293 q = nq;
294 }
295
296 /* Insert the new segment queue entry into place. */
297 te->tqe_m = m;
298 te->tqe_th = th;
299 te->tqe_len = *tlenp;
300
301 if (p == NULL) {
302 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
303 } else {
304 LIST_INSERT_AFTER(p, te, tqe_q);
305 }
306
307present:
308 /*
309 * Present data to user, advancing rcv_nxt through
310 * completed sequence space.
311 */
312 if (!TCPS_HAVEESTABLISHED(tp->t_state))
313 return (0);
314 q = LIST_FIRST(&tp->t_segq);
315 if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
316 return (0);
317 SOCKBUF_LOCK(&so->so_rcv);
318 do {
319 tp->rcv_nxt += q->tqe_len;
320 flags = q->tqe_th->th_flags & TH_FIN;
321 nq = LIST_NEXT(q, tqe_q);
322 LIST_REMOVE(q, tqe_q);
323 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
324 m_freem(q->tqe_m);
325 else
326 sbappendstream_locked(&so->so_rcv, q->tqe_m);
327 uma_zfree(V_tcp_reass_zone, q);
328 tp->t_segqlen--;
329 q = nq;
330 } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
331 ND6_HINT(tp);
332 sorwakeup_locked(so);
333 return (flags);
334}
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