2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
4 * Copyright (c) 1982, 1986, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/socket.h>
42 #include <sys/socketvar.h>
44 #include <sys/malloc.h>
45 #include <sys/queue.h>
46 #include <sys/kernel.h>
47 #include <sys/resourcevar.h>
48 #include <vm/vm_zone.h>
52 #include <netinet/in.h>
53 #include <netinet/in_var.h>
54 #include <netinet/tcp.h>
56 #include <net/pf/pfvar.h>
58 #include <sys/random.h>
61 * This implements additional functions used by pf which can not be ported
62 * easyly. At this point it boils down to mostly the Net/OpenBSD hook
65 * BEWARE: this is not locked! Required locking is done by the caller.
69 hook_establish(struct hook_desc_head *head, int tail, void (*fn)(void *),
72 struct hook_desc *hdp;
74 hdp = kmalloc(sizeof (*hdp), M_DEVBUF, M_WAITOK);
81 TAILQ_INSERT_TAIL(head, hdp, hd_list);
83 TAILQ_INSERT_HEAD(head, hdp, hd_list);
89 hook_disestablish(struct hook_desc_head *head, void *vhook)
91 struct hook_desc *hdp;
94 for (hdp = TAILQ_FIRST(head); hdp != NULL;
95 hdp = TAILQ_NEXT(hdp, hd_list))
99 panic("hook_disestablish: hook not established");
102 TAILQ_REMOVE(head, hdp, hd_list);
103 kfree(hdp, M_DEVBUF);
107 * Run hooks. Startup hooks are invoked right after scheduler_start but
108 * before root is mounted. Shutdown hooks are invoked immediately before the
109 * system is halted or rebooted, i.e. after file systems unmounted,
110 * after crash dump done, etc.
113 dohooks(struct hook_desc_head *head, int flags)
115 struct hook_desc *hdp;
117 if ((flags & HOOK_REMOVE) == 0) {
118 TAILQ_FOREACH(hdp, head, hd_list) {
119 (*hdp->hd_fn)(hdp->hd_arg);
122 while ((hdp = TAILQ_FIRST(head)) != NULL) {
123 TAILQ_REMOVE(head, hdp, hd_list);
124 (*hdp->hd_fn)(hdp->hd_arg);
125 if ((flags & HOOK_FREE) != 0)
126 kfree(hdp, M_DEVBUF);
133 * Following is where TCP initial sequence number generation occurs.
135 * There are two places where we must use initial sequence numbers:
136 * 1. In SYN-ACK packets.
139 * All ISNs for SYN-ACK packets are generated by the syncache. See
140 * tcp_syncache.c for details.
142 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
143 * depends on this property. In addition, these ISNs should be
144 * unguessable so as to prevent connection hijacking. To satisfy
145 * the requirements of this situation, the algorithm outlined in
146 * RFC 1948 is used, with only small modifications.
148 * Implementation details:
150 * Time is based off the system timer, and is corrected so that it
151 * increases by one megabyte per second. This allows for proper
152 * recycling on high speed LANs while still leaving over an hour
155 * As reading the *exact* system time is too expensive to be done
156 * whenever setting up a TCP connection, we increment the time
157 * offset in two ways. First, a small random positive increment
158 * is added to isn_offset for each connection that is set up.
159 * Second, the function tcp_isn_tick fires once per clock tick
160 * and increments isn_offset as necessary so that sequence numbers
161 * are incremented at approximately ISN_BYTES_PER_SECOND. The
162 * random positive increments serve only to ensure that the same
163 * exact sequence number is never sent out twice (as could otherwise
164 * happen when a port is recycled in less than the system tick
167 * net.inet.tcp.isn_reseed_interval controls the number of seconds
168 * between seeding of isn_secret. This is normally set to zero,
169 * as reseeding should not be necessary.
171 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
172 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In
173 * general, this means holding an exclusive (write) lock.
176 #define ISN_BYTES_PER_SECOND 1048576
177 #define ISN_STATIC_INCREMENT 4096
178 #define ISN_RANDOM_INCREMENT (4096 - 1)
180 static u_char pf_isn_secret[32];
181 static int pf_isn_last_reseed;
182 static u_int32_t pf_isn_offset;
185 pf_new_isn(struct pf_state_key *sk) /* From FreeBSD */
188 u_int32_t md5_buffer[4];
190 struct pf_state_host *src, *dst;
192 /* Seed if this is the first use, reseed if requested. */
193 if (pf_isn_last_reseed == 0) {
194 read_random_unlimited(&pf_isn_secret, sizeof(pf_isn_secret));
195 pf_isn_last_reseed = ticks;
198 if (sk->direction == PF_IN) {
206 /* Compute the md5 hash and return the ISN. */
208 MD5Update(&isn_ctx, (u_char *) &dst->port, sizeof(u_short));
209 MD5Update(&isn_ctx, (u_char *) &src->port, sizeof(u_short));
211 if (sk->af == AF_INET6) {
212 MD5Update(&isn_ctx, (u_char *) &dst->addr,
213 sizeof(struct in6_addr));
214 MD5Update(&isn_ctx, (u_char *) &src->addr,
215 sizeof(struct in6_addr));
219 MD5Update(&isn_ctx, (u_char *) &dst->addr,
220 sizeof(struct in_addr));
221 MD5Update(&isn_ctx, (u_char *) &src->addr,
222 sizeof(struct in_addr));
224 MD5Update(&isn_ctx, (u_char *) &pf_isn_secret, sizeof(pf_isn_secret));
225 MD5Final((u_char *) &md5_buffer, &isn_ctx);
226 new_isn = (tcp_seq) md5_buffer[0];
227 pf_isn_offset += ISN_STATIC_INCREMENT +
228 (karc4random() & ISN_RANDOM_INCREMENT);
229 new_isn += pf_isn_offset;