1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
|
/* $OpenBSD: pfutils.c,v 1.13 2015/02/05 09:42:52 krw Exp $ */
/*
* Copyright (c) 2006 Chris Kuethe <ckuethe@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <net/pfvar.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "dhcpd.h"
extern struct passwd *pw;
extern int pfpipe[2];
extern int gotpipe;
extern char *abandoned_tab;
extern char *changedmac_tab;
extern char *leased_tab;
__dead void
pftable_handler()
{
struct pf_cmd cmd;
struct pollfd pfd[1];
int l, r, fd, nfds;
if ((fd = open(_PATH_DEV_PF, O_RDWR|O_NOFOLLOW, 0660)) == -1)
error("can't open pf device: %m");
if (chroot(_PATH_VAREMPTY) == -1)
error("chroot %s: %m", _PATH_VAREMPTY);
if (chdir("/") == -1)
error("chdir(\"/\"): %m");
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
error("can't drop privileges: %m");
setproctitle("pf table handler");
l = sizeof(struct pf_cmd);
for (;;) {
pfd[0].fd = pfpipe[0];
pfd[0].events = POLLIN;
if ((nfds = poll(pfd, 1, -1)) == -1)
if (errno != EINTR)
error("poll: %m");
if (nfds > 0 && (pfd[0].revents & POLLHUP))
error("pf pipe closed");
if (nfds > 0 && (pfd[0].revents & POLLIN)) {
bzero(&cmd, l);
r = atomicio(read, pfpipe[0], &cmd, l);
if (r != l)
error("pf pipe error: %m");
switch (cmd.type) {
case 'A':
/*
* When we abandon an address, we add it to
* the table of abandoned addresses, and remove
* it from the table of active leases.
*/
pf_change_table(fd, 1, cmd.ip, abandoned_tab);
pf_change_table(fd, 0, cmd.ip, leased_tab);
pf_kill_state(fd, cmd.ip);
break;
case 'C':
/*
* When the hardware address for an IP changes,
* remove it from the table of abandoned
* addresses, and from the table of overloaded
* addresses.
*/
pf_change_table(fd, 0, cmd.ip, abandoned_tab);
pf_change_table(fd, 0, cmd.ip, changedmac_tab);
break;
case 'L':
/*
* When a lease is granted or renewed, remove
* it from the table of abandoned addresses,
* and ensure it is in the table of active
* leases.
*/
pf_change_table(fd, 0, cmd.ip, abandoned_tab);
pf_change_table(fd, 1, cmd.ip, leased_tab);
break;
case 'R':
/*
* When we release or expire a lease, remove
* it from the table of active leases. As long
* as dhcpd doesn't abandon the address, no
* further action is required.
*/
pf_change_table(fd, 0, cmd.ip, leased_tab);
break;
default:
break;
}
}
}
/* not reached */
exit(1);
}
/* inspired by ("stolen") from usr.sbin/authpf/authpf.c */
void
pf_change_table(int fd, int op, struct in_addr ip, char *table)
{
struct pfioc_table io;
struct pfr_addr addr;
if (table == NULL)
return;
bzero(&io, sizeof(io));
strlcpy(io.pfrio_table.pfrt_name, table,
sizeof(io.pfrio_table.pfrt_name));
io.pfrio_buffer = &addr;
io.pfrio_esize = sizeof(addr);
io.pfrio_size = 1;
bzero(&addr, sizeof(addr));
memcpy(&addr.pfra_ip4addr, &ip, 4);
addr.pfra_af = AF_INET;
addr.pfra_net = 32;
if (ioctl(fd, op ? DIOCRADDADDRS : DIOCRDELADDRS, &io) &&
errno != ESRCH) {
warning( "DIOCR%sADDRS on table %s: %s",
op ? "ADD" : "DEL", table, strerror(errno));
}
}
void
pf_kill_state(int fd, struct in_addr ip)
{
struct pfioc_state_kill psk;
struct pf_addr target;
bzero(&psk, sizeof(psk));
bzero(&target, sizeof(target));
memcpy(&target.v4, &ip.s_addr, 4);
psk.psk_af = AF_INET;
/* Kill all states from target */
memcpy(&psk.psk_src.addr.v.a.addr, &target,
sizeof(psk.psk_src.addr.v.a.addr));
memset(&psk.psk_src.addr.v.a.mask, 0xff,
sizeof(psk.psk_src.addr.v.a.mask));
if (ioctl(fd, DIOCKILLSTATES, &psk)) {
warning("DIOCKILLSTATES failed (%s)", strerror(errno));
}
/* Kill all states to target */
bzero(&psk.psk_src, sizeof(psk.psk_src));
memcpy(&psk.psk_dst.addr.v.a.addr, &target,
sizeof(psk.psk_dst.addr.v.a.addr));
memset(&psk.psk_dst.addr.v.a.mask, 0xff,
sizeof(psk.psk_dst.addr.v.a.mask));
if (ioctl(fd, DIOCKILLSTATES, &psk)) {
warning("DIOCKILLSTATES failed (%s)", strerror(errno));
}
}
/* inspired by ("stolen") from usr.bin/ssh/atomicio.c */
size_t
atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
{
char *s = _s;
size_t pos = 0;
ssize_t res;
while (n > pos) {
res = (f) (fd, s + pos, n - pos);
switch (res) {
case -1:
if (errno == EINTR || errno == EAGAIN)
continue;
return 0;
case 0:
errno = EPIPE;
return pos;
default:
pos += (size_t)res;
}
}
return (pos);
}
/*
* This function sends commands to the pf table handler. It will safely and
* silently return if the handler is unconfigured, therefore it can be called
* on all interesting lease events, whether or not the user actually wants to
* use the pf table feature.
*/
void
pfmsg(char c, struct lease *lp)
{
struct pf_cmd cmd;
if (gotpipe == 0)
return;
cmd.type = c;
memcpy(&cmd.ip.s_addr, lp->ip_addr.iabuf, 4);
switch (c) {
case 'A': /* address is being abandoned */
/* FALLTHROUGH */
case 'C': /* IP moved to different ethernet address */
/* FALLTHROUGH */
case 'L': /* Address is being leased (unabandoned) */
/* FALLTHROUGH */
case 'R': /* Address is being released or lease has expired */
(void)atomicio(vwrite, pfpipe[1], &cmd,
sizeof(struct pf_cmd));
break;
default: /* silently ignore unknown commands */
break;
}
}
|
