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>
33 __FBSDID("$FreeBSD: releng/8.1/sys/netinet/tcp_reass.c 207695 2010-05-06 06:44:19Z bz $");
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
77 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
78 "TCP Segment Reassembly Queue");
79
80 static VNET_DEFINE(int, tcp_reass_maxseg) = 0;
81 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg)
82 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
83 &VNET_NAME(tcp_reass_maxseg), 0,
84 "Global maximum number of TCP Segments in Reassembly Queue");
85
86 VNET_DEFINE(int, tcp_reass_qsize) = 0;
87 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
88 &VNET_NAME(tcp_reass_qsize), 0,
89 "Global number of TCP Segments currently in Reassembly Queue");
90
91 static VNET_DEFINE(int, tcp_reass_maxqlen) = 48;
92 #define V_tcp_reass_maxqlen VNET(tcp_reass_maxqlen)
93 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxqlen, CTLFLAG_RW,
94 &VNET_NAME(tcp_reass_maxqlen), 0,
95 "Maximum number of TCP Segments per individual Reassembly Queue");
96
97 static VNET_DEFINE(int, tcp_reass_overflows) = 0;
98 #define V_tcp_reass_overflows VNET(tcp_reass_overflows)
99 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
100 &VNET_NAME(tcp_reass_overflows), 0,
101 "Global number of TCP Segment Reassembly Queue Overflows");
102
103 /* Initialize TCP reassembly queue */
104 static void
105 tcp_reass_zone_change(void *tag)
106 {
107
108 V_tcp_reass_maxseg = nmbclusters / 16;
109 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
110 }
111
112 VNET_DEFINE(uma_zone_t, tcp_reass_zone);
113
114 void
115 tcp_reass_init(void)
116 {
117
118 V_tcp_reass_maxseg = nmbclusters / 16;
119 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
120 &V_tcp_reass_maxseg);
121 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
122 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
123 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
124 EVENTHANDLER_REGISTER(nmbclusters_change,
125 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
126 }
127
128 #ifdef VIMAGE
129 void
130 tcp_reass_destroy(void)
131 {
132
133 uma_zdestroy(V_tcp_reass_zone);
134 }
135 #endif
136
137 int
138 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
139 {
140 struct tseg_qent *q;
141 struct tseg_qent *p = NULL;
142 struct tseg_qent *nq;
143 struct tseg_qent *te = NULL;
144 struct socket *so = tp->t_inpcb->inp_socket;
145 int flags;
146
147 INP_WLOCK_ASSERT(tp->t_inpcb);
148
149 /*
150 * XXX: tcp_reass() is rather inefficient with its data structures
151 * and should be rewritten (see NetBSD for optimizations).
152 */
153
154 /*
155 * Call with th==NULL after become established to
156 * force pre-ESTABLISHED data up to user socket.
157 */
158 if (th == NULL)
159 goto present;
160
161 /*
162 * Limit the number of segments in the reassembly queue to prevent
163 * holding on to too many segments (and thus running out of mbufs).
164 * Make sure to let the missing segment through which caused this
165 * queue. Always keep one global queue entry spare to be able to
166 * process the missing segment.
167 */
168 if (th->th_seq != tp->rcv_nxt &&
169 (V_tcp_reass_qsize + 1 >= V_tcp_reass_maxseg ||
170 tp->t_segqlen >= V_tcp_reass_maxqlen)) {
171 V_tcp_reass_overflows++;
172 TCPSTAT_INC(tcps_rcvmemdrop);
173 m_freem(m);
174 *tlenp = 0;
175 return (0);
176 }
177
178 /*
179 * Allocate a new queue entry. If we can't, or hit the zone limit
180 * just drop the pkt.
181 */
182 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT);
183 if (te == NULL) {
184 TCPSTAT_INC(tcps_rcvmemdrop);
185 m_freem(m);
186 *tlenp = 0;
187 return (0);
188 }
189 tp->t_segqlen++;
190 V_tcp_reass_qsize++;
191
192 /*
193 * Find a segment which begins after this one does.
194 */
195 LIST_FOREACH(q, &tp->t_segq, tqe_q) {
196 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
197 break;
198 p = q;
199 }
200
201 /*
202 * If there is a preceding segment, it may provide some of
203 * our data already. If so, drop the data from the incoming
204 * segment. If it provides all of our data, drop us.
205 */
206 if (p != NULL) {
207 int i;
208 /* conversion to int (in i) handles seq wraparound */
209 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
210 if (i > 0) {
211 if (i >= *tlenp) {
212 TCPSTAT_INC(tcps_rcvduppack);
213 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
214 m_freem(m);
215 uma_zfree(V_tcp_reass_zone, te);
216 tp->t_segqlen--;
217 V_tcp_reass_qsize--;
218 /*
219 * Try to present any queued data
220 * at the left window edge to the user.
221 * This is needed after the 3-WHS
222 * completes.
223 */
224 goto present; /* ??? */
225 }
226 m_adj(m, i);
227 *tlenp -= i;
228 th->th_seq += i;
229 }
230 }
231 TCPSTAT_INC(tcps_rcvoopack);
232 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
233
234 /*
235 * While we overlap succeeding segments trim them or,
236 * if they are completely covered, dequeue them.
237 */
238 while (q) {
239 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
240 if (i <= 0)
241 break;
242 if (i < q->tqe_len) {
243 q->tqe_th->th_seq += i;
244 q->tqe_len -= i;
245 m_adj(q->tqe_m, i);
246 break;
247 }
248
249 nq = LIST_NEXT(q, tqe_q);
250 LIST_REMOVE(q, tqe_q);
251 m_freem(q->tqe_m);
252 uma_zfree(V_tcp_reass_zone, q);
253 tp->t_segqlen--;
254 V_tcp_reass_qsize--;
255 q = nq;
256 }
257
258 /* Insert the new segment queue entry into place. */
259 te->tqe_m = m;
260 te->tqe_th = th;
261 te->tqe_len = *tlenp;
262
263 if (p == NULL) {
264 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
265 } else {
266 LIST_INSERT_AFTER(p, te, tqe_q);
267 }
268
269 present:
270 /*
271 * Present data to user, advancing rcv_nxt through
272 * completed sequence space.
273 */
274 if (!TCPS_HAVEESTABLISHED(tp->t_state))
275 return (0);
276 q = LIST_FIRST(&tp->t_segq);
277 if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
278 return (0);
279 SOCKBUF_LOCK(&so->so_rcv);
280 do {
281 tp->rcv_nxt += q->tqe_len;
282 flags = q->tqe_th->th_flags & TH_FIN;
283 nq = LIST_NEXT(q, tqe_q);
284 LIST_REMOVE(q, tqe_q);
285 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
286 m_freem(q->tqe_m);
287 else
288 sbappendstream_locked(&so->so_rcv, q->tqe_m);
289 uma_zfree(V_tcp_reass_zone, q);
290 tp->t_segqlen--;
291 V_tcp_reass_qsize--;
292 q = nq;
293 } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
294 ND6_HINT(tp);
295 sorwakeup_locked(so);
296 return (flags);
297 }
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