1 /*	$OpenBSD: control.c,v 1.17 2024/11/21 13:35:20 claudio Exp $	*/
2 
3 /*
4  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 #ifndef SMALL
19 #include <sys/types.h>
20 #include <sys/queue.h>
21 #include <sys/stat.h>
22 #include <sys/socket.h>
23 #include <sys/uio.h>
24 #include <sys/un.h>
25 
26 #include <net/if.h>
27 #include <netinet/in.h>
28 #include <netinet/if_ether.h>
29 
30 #include <errno.h>
31 #include <event.h>
32 #include <imsg.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 
37 #include "log.h"
38 #include "slaacd.h"
39 #include "control.h"
40 #include "frontend.h"
41 
42 #define	CONTROL_BACKLOG	5
43 
44 struct {
45 	struct event	ev;
46 	struct event	evt;
47 	int		fd;
48 } control_state = {.fd = -1};
49 
50 struct ctl_conn {
51 	TAILQ_ENTRY(ctl_conn)	entry;
52 	struct imsgev		iev;
53 };
54 
55 struct ctl_conn	*control_connbyfd(int);
56 struct ctl_conn	*control_connbypid(pid_t);
57 void		 control_close(int);
58 
59 TAILQ_HEAD(ctl_conns, ctl_conn) ctl_conns = TAILQ_HEAD_INITIALIZER(ctl_conns);
60 
61 int
control_init(char * path)62 control_init(char *path)
63 {
64 	struct sockaddr_un	 sun;
65 	int			 fd;
66 	mode_t			 old_umask;
67 
68 	if ((fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
69 	    0)) == -1) {
70 		log_warn("%s: socket", __func__);
71 		return (-1);
72 	}
73 
74 	memset(&sun, 0, sizeof(sun));
75 	sun.sun_family = AF_UNIX;
76 	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
77 
78 	if (unlink(path) == -1)
79 		if (errno != ENOENT) {
80 			log_warn("%s: unlink %s", __func__, path);
81 			close(fd);
82 			return (-1);
83 		}
84 
85 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
86 	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
87 		log_warn("%s: bind: %s", __func__, path);
88 		close(fd);
89 		umask(old_umask);
90 		return (-1);
91 	}
92 	umask(old_umask);
93 
94 	if (chmod(path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) {
95 		log_warn("%s: chmod", __func__);
96 		close(fd);
97 		(void)unlink(path);
98 		return (-1);
99 	}
100 
101 	return (fd);
102 }
103 
104 int
control_listen(int fd)105 control_listen(int fd)
106 {
107 	if (control_state.fd != -1)
108 		fatalx("%s: received unexpected controlsock", __func__);
109 
110 	control_state.fd = fd;
111 	if (listen(control_state.fd, CONTROL_BACKLOG) == -1) {
112 		log_warn("%s: listen", __func__);
113 		return (-1);
114 	}
115 
116 	event_set(&control_state.ev, control_state.fd, EV_READ,
117 	    control_accept, NULL);
118 	event_add(&control_state.ev, NULL);
119 	evtimer_set(&control_state.evt, control_accept, NULL);
120 
121 	return (0);
122 }
123 
124 void
control_accept(int listenfd,short event,void * bula)125 control_accept(int listenfd, short event, void *bula)
126 {
127 	int			 connfd;
128 	socklen_t		 len;
129 	struct sockaddr_un	 sun;
130 	struct ctl_conn		*c;
131 
132 	event_add(&control_state.ev, NULL);
133 	if ((event & EV_TIMEOUT))
134 		return;
135 
136 	len = sizeof(sun);
137 	if ((connfd = accept4(listenfd, (struct sockaddr *)&sun, &len,
138 	    SOCK_CLOEXEC | SOCK_NONBLOCK)) == -1) {
139 		/*
140 		 * Pause accept if we are out of file descriptors, or
141 		 * libevent will haunt us here too.
142 		 */
143 		if (errno == ENFILE || errno == EMFILE) {
144 			struct timeval evtpause = { 1, 0 };
145 
146 			event_del(&control_state.ev);
147 			evtimer_add(&control_state.evt, &evtpause);
148 		} else if (errno != EWOULDBLOCK && errno != EINTR &&
149 		    errno != ECONNABORTED)
150 			log_warn("%s: accept4", __func__);
151 		return;
152 	}
153 
154 	if ((c = calloc(1, sizeof(struct ctl_conn))) == NULL) {
155 		log_warn("%s: calloc", __func__);
156 		close(connfd);
157 		return;
158 	}
159 
160 	if (imsgbuf_init(&c->iev.ibuf, connfd) == -1) {
161 		log_warn("%s: imsgbuf_init", __func__);
162 		close(connfd);
163 		free(c);
164 		return;
165 	}
166 	c->iev.handler = control_dispatch_imsg;
167 	c->iev.events = EV_READ;
168 	event_set(&c->iev.ev, c->iev.ibuf.fd, c->iev.events,
169 	    c->iev.handler, &c->iev);
170 	event_add(&c->iev.ev, NULL);
171 
172 	TAILQ_INSERT_TAIL(&ctl_conns, c, entry);
173 }
174 
175 struct ctl_conn *
control_connbyfd(int fd)176 control_connbyfd(int fd)
177 {
178 	struct ctl_conn	*c;
179 
180 	TAILQ_FOREACH(c, &ctl_conns, entry) {
181 		if (c->iev.ibuf.fd == fd)
182 			break;
183 	}
184 
185 	return (c);
186 }
187 
188 struct ctl_conn *
control_connbypid(pid_t pid)189 control_connbypid(pid_t pid)
190 {
191 	struct ctl_conn	*c;
192 
193 	TAILQ_FOREACH(c, &ctl_conns, entry) {
194 		if (c->iev.ibuf.pid == pid)
195 			break;
196 	}
197 
198 	return (c);
199 }
200 
201 void
control_close(int fd)202 control_close(int fd)
203 {
204 	struct ctl_conn	*c;
205 
206 	if ((c = control_connbyfd(fd)) == NULL) {
207 		log_warnx("%s: fd %d: not found", __func__, fd);
208 		return;
209 	}
210 
211 	imsgbuf_clear(&c->iev.ibuf);
212 	TAILQ_REMOVE(&ctl_conns, c, entry);
213 
214 	event_del(&c->iev.ev);
215 	close(c->iev.ibuf.fd);
216 
217 	/* Some file descriptors are available again. */
218 	if (evtimer_pending(&control_state.evt, NULL)) {
219 		evtimer_del(&control_state.evt);
220 		event_add(&control_state.ev, NULL);
221 	}
222 
223 	free(c);
224 }
225 
226 void
control_dispatch_imsg(int fd,short event,void * bula)227 control_dispatch_imsg(int fd, short event, void *bula)
228 {
229 	struct ctl_conn	*c;
230 	struct imsg	 imsg;
231 	ssize_t		 n;
232 	int		 verbose;
233 	uint32_t	 if_index, type;
234 	pid_t		 pid;
235 
236 	if ((c = control_connbyfd(fd)) == NULL) {
237 		log_warnx("%s: fd %d: not found", __func__, fd);
238 		return;
239 	}
240 
241 	if (event & EV_READ) {
242 		if (imsgbuf_read(&c->iev.ibuf) != 1) {
243 			control_close(fd);
244 			return;
245 		}
246 	}
247 	if (event & EV_WRITE) {
248 		if (imsgbuf_write(&c->iev.ibuf) == -1) {
249 			control_close(fd);
250 			return;
251 		}
252 	}
253 
254 	for (;;) {
255 		if ((n = imsg_get(&c->iev.ibuf, &imsg)) == -1) {
256 			control_close(fd);
257 			return;
258 		}
259 		if (n == 0)
260 			break;
261 
262 		type = imsg_get_type(&imsg);
263 		pid = imsg_get_pid(&imsg);
264 		switch (type) {
265 		case IMSG_CTL_LOG_VERBOSE:
266 			if (imsg_get_data(&imsg, &verbose,
267 			    sizeof(verbose)) == -1)
268 				break;
269 
270 			/* Forward to all other processes. */
271 			frontend_imsg_compose_main(type, pid, &verbose,
272 			    sizeof(verbose));
273 			frontend_imsg_compose_engine(type, 0, pid, &verbose,
274 			    sizeof(verbose));
275 
276 			log_setverbose(verbose);
277 			break;
278 		case IMSG_CTL_SHOW_INTERFACE_INFO:
279 		case IMSG_CTL_SEND_SOLICITATION:
280 			if (imsg_get_data(&imsg, &if_index,
281 			    sizeof(if_index)) == -1)
282 				break;
283 
284 			c->iev.ibuf.pid = pid;
285 			frontend_imsg_compose_engine(type, 0, pid, &if_index,
286 			    sizeof(if_index));
287 			break;
288 		default:
289 			log_debug("%s: error handling imsg %d", __func__, type);
290 			break;
291 		}
292 		imsg_free(&imsg);
293 	}
294 
295 	imsg_event_add(&c->iev);
296 }
297 
298 int
control_imsg_relay(struct imsg * imsg)299 control_imsg_relay(struct imsg *imsg)
300 {
301 	struct ctl_conn	*c;
302 
303 	if ((c = control_connbypid(imsg_get_pid(imsg))) == NULL)
304 		return (0);
305 
306 	return (imsg_forward_event(&c->iev, imsg));
307 }
308 #endif	/* SMALL */
309