1 /* $OpenBSD: fingerd.c,v 1.42 2021/07/12 15:09:18 beck Exp $ */
2
3 /*
4 * Copyright (c) 1983, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/socket.h>
33 #include <netinet/in.h>
34 #include <arpa/inet.h>
35 #include <errno.h>
36
37 #include <err.h>
38 #include <unistd.h>
39 #include <syslog.h>
40 #include <netdb.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <stdarg.h>
45 #include <limits.h>
46 #include "pathnames.h"
47
48 __dead void logerr(const char *, ...);
49 __dead void usage(void);
50
51 void
usage(void)52 usage(void)
53 {
54 syslog(LOG_ERR,
55 "usage: fingerd [-lMmpSsu] [-P filename]");
56 exit(2);
57 }
58
59
60 int
main(int argc,char * argv[])61 main(int argc, char *argv[])
62 {
63 FILE *fp;
64 int ch, ac = 2;
65 int p[2], logging, secure, user_required, short_list;
66 #define ENTRIES 50
67 char **comp, *prog;
68 char **ap, *av[ENTRIES + 1], line[8192], *lp, *hname;
69 char hostbuf[HOST_NAME_MAX+1];
70
71 prog = _PATH_FINGER;
72 logging = secure = user_required = short_list = 0;
73 openlog("fingerd", LOG_PID, LOG_DAEMON);
74 opterr = 0;
75 while ((ch = getopt(argc, argv, "sluSmMpP:")) != -1)
76 switch (ch) {
77 case 'l':
78 logging = 1;
79 break;
80 case 'P':
81 prog = optarg;
82 break;
83 case 's':
84 secure = 1;
85 break;
86 case 'u':
87 user_required = 1;
88 break;
89 case 'S':
90 if (ac < ENTRIES) {
91 short_list = 1;
92 av[ac++] = "-s";
93 }
94 break;
95 case 'm':
96 if (ac < ENTRIES)
97 av[ac++] = "-m";
98 break;
99 case 'M':
100 if (ac < ENTRIES)
101 av[ac++] = "-M";
102 break;
103 case 'p':
104 if (ac < ENTRIES)
105 av[ac++] = "-p";
106 break;
107 default:
108 usage();
109 }
110
111 if (unveil(prog, "x") == -1)
112 err(1, "unveil %s", prog);
113 if (pledge("stdio inet dns proc exec", NULL) == -1)
114 err(1, "pledge");
115
116 if (logging) {
117 struct sockaddr_storage ss;
118 struct sockaddr *sa;
119 socklen_t sval;
120
121 sval = sizeof(ss);
122 if (getpeername(0, (struct sockaddr *)&ss, &sval) == -1)
123 err(1, "getpeername");
124 sa = (struct sockaddr *)&ss;
125
126 if (pledge("stdio dns proc exec", NULL) == -1)
127 err(1, "pledge");
128
129 if (getnameinfo(sa, sa->sa_len, hostbuf, sizeof(hostbuf),
130 NULL, 0, 0) != 0) {
131 strlcpy(hostbuf, "?", sizeof(hostbuf));
132 }
133 hname = hostbuf;
134 }
135
136 if (pledge("stdio proc exec", NULL) == -1)
137 err(1, "pledge");
138
139 if (fgets(line, sizeof(line), stdin) == NULL) {
140 if (logging)
141 syslog(LOG_NOTICE, "query from %s: %s", hname,
142 feof(stdin) ? "EOF" : strerror(errno));
143 exit(1);
144 }
145
146 if (logging)
147 syslog(LOG_NOTICE, "query from %s: `%.*s'", hname,
148 (int)strcspn(line, "\r\n"), line);
149
150 /*
151 * Note: we assume that finger(1) will treat "--" as end of
152 * command args (ie: that it uses getopt(3)).
153 */
154 av[ac++] = "--";
155 comp = &av[1];
156 for (lp = line, ap = &av[ac]; ac < ENTRIES;) {
157 size_t len;
158
159 if ((*ap = strtok(lp, " \t\r\n")) == NULL)
160 break;
161 lp = NULL;
162 if (secure && strchr(*ap, '@')) {
163 (void) puts("forwarding service denied\r");
164 exit(1);
165 }
166
167 len = strlen(*ap);
168 while (len > 0 && (*ap)[len - 1] == '@')
169 (*ap)[--len] = '\0';
170 if (**ap == '\0')
171 continue;
172
173 /* RFC1196: "/[Ww]" == "-l" */
174 if ((*ap)[0] == '/' && ((*ap)[1] == 'W' || (*ap)[1] == 'w')) {
175 if (!short_list) {
176 av[1] = "-l";
177 comp = &av[0];
178 }
179 } else {
180 ap++;
181 ac++;
182 }
183 }
184 av[ENTRIES - 1] = NULL;
185
186 if ((lp = strrchr(prog, '/')))
187 *comp = ++lp;
188 else
189 *comp = prog;
190
191 if (user_required) {
192 for (ap = comp + 1; strcmp("--", *(ap++)); )
193 ;
194 if (*ap == NULL) {
195 (void) puts("must provide username\r");
196 exit(1);
197 }
198 }
199
200 if (pipe(p) == -1)
201 logerr("pipe: %s", strerror(errno));
202
203 switch (vfork()) {
204 case 0:
205 (void) close(p[0]);
206 if (p[1] != 1) {
207 (void) dup2(p[1], 1);
208 (void) close(p[1]);
209 }
210 execv(prog, comp);
211 syslog(LOG_ERR, "execv: %s: %s", prog, strerror(errno));
212 _exit(1);
213 case -1:
214 logerr("fork: %s", strerror(errno));
215 }
216 if (pledge("stdio", NULL) == -1)
217 err(1, "pledge");
218
219 (void) close(p[1]);
220 if (!(fp = fdopen(p[0], "r")))
221 logerr("fdopen: %s", strerror(errno));
222 while ((ch = getc(fp)) != EOF) {
223 if (ch == '\n')
224 putchar('\r');
225 putchar(ch);
226 }
227 exit(0);
228 }
229
230 void
logerr(const char * fmt,...)231 logerr(const char *fmt, ...)
232 {
233 va_list ap;
234
235 va_start(ap, fmt);
236 (void) vsyslog(LOG_ERR, fmt, ap);
237 va_end(ap);
238 exit(1);
239 }
240