1 /* $OpenBSD: proc.c,v 1.30 2024/11/21 13:35:20 claudio Exp $ */
2
3 /*
4 * Copyright (c) 2015 Nicholas Marriott <nicholas.marriott@gmail.com>
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 MIND, USE, DATA OR PROFITS, WHETHER
15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/types.h>
20 #include <sys/queue.h>
21 #include <sys/socket.h>
22 #include <sys/uio.h>
23 #include <sys/utsname.h>
24
25 #include <errno.h>
26 #include <event.h>
27 #include <imsg.h>
28 #include <signal.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <unistd.h>
32
33 #include "tmux.h"
34
35 struct tmuxproc {
36 const char *name;
37 int exit;
38
39 void (*signalcb)(int);
40
41 struct event ev_sigint;
42 struct event ev_sighup;
43 struct event ev_sigchld;
44 struct event ev_sigcont;
45 struct event ev_sigterm;
46 struct event ev_sigusr1;
47 struct event ev_sigusr2;
48 struct event ev_sigwinch;
49
50 TAILQ_HEAD(, tmuxpeer) peers;
51 };
52
53 struct tmuxpeer {
54 struct tmuxproc *parent;
55
56 struct imsgbuf ibuf;
57 struct event event;
58 uid_t uid;
59
60 int flags;
61 #define PEER_BAD 0x1
62
63 void (*dispatchcb)(struct imsg *, void *);
64 void *arg;
65
66 TAILQ_ENTRY(tmuxpeer) entry;
67 };
68
69 static int peer_check_version(struct tmuxpeer *, struct imsg *);
70 static void proc_update_event(struct tmuxpeer *);
71
72 static void
proc_event_cb(__unused int fd,short events,void * arg)73 proc_event_cb(__unused int fd, short events, void *arg)
74 {
75 struct tmuxpeer *peer = arg;
76 ssize_t n;
77 struct imsg imsg;
78
79 if (!(peer->flags & PEER_BAD) && (events & EV_READ)) {
80 if (imsgbuf_read(&peer->ibuf) != 1) {
81 peer->dispatchcb(NULL, peer->arg);
82 return;
83 }
84 for (;;) {
85 if ((n = imsg_get(&peer->ibuf, &imsg)) == -1) {
86 peer->dispatchcb(NULL, peer->arg);
87 return;
88 }
89 if (n == 0)
90 break;
91 log_debug("peer %p message %d", peer, imsg.hdr.type);
92
93 if (peer_check_version(peer, &imsg) != 0) {
94 fd = imsg_get_fd(&imsg);
95 if (fd != -1)
96 close(fd);
97 imsg_free(&imsg);
98 break;
99 }
100
101 peer->dispatchcb(&imsg, peer->arg);
102 imsg_free(&imsg);
103 }
104 }
105
106 if (events & EV_WRITE) {
107 if (imsgbuf_write(&peer->ibuf) == -1) {
108 peer->dispatchcb(NULL, peer->arg);
109 return;
110 }
111 }
112
113 if ((peer->flags & PEER_BAD) && imsgbuf_queuelen(&peer->ibuf) == 0) {
114 peer->dispatchcb(NULL, peer->arg);
115 return;
116 }
117
118 proc_update_event(peer);
119 }
120
121 static void
proc_signal_cb(int signo,__unused short events,void * arg)122 proc_signal_cb(int signo, __unused short events, void *arg)
123 {
124 struct tmuxproc *tp = arg;
125
126 tp->signalcb(signo);
127 }
128
129 static int
peer_check_version(struct tmuxpeer * peer,struct imsg * imsg)130 peer_check_version(struct tmuxpeer *peer, struct imsg *imsg)
131 {
132 int version;
133
134 version = imsg->hdr.peerid & 0xff;
135 if (imsg->hdr.type != MSG_VERSION && version != PROTOCOL_VERSION) {
136 log_debug("peer %p bad version %d", peer, version);
137
138 proc_send(peer, MSG_VERSION, -1, NULL, 0);
139 peer->flags |= PEER_BAD;
140
141 return (-1);
142 }
143 return (0);
144 }
145
146 static void
proc_update_event(struct tmuxpeer * peer)147 proc_update_event(struct tmuxpeer *peer)
148 {
149 short events;
150
151 event_del(&peer->event);
152
153 events = EV_READ;
154 if (imsgbuf_queuelen(&peer->ibuf) > 0)
155 events |= EV_WRITE;
156 event_set(&peer->event, peer->ibuf.fd, events, proc_event_cb, peer);
157
158 event_add(&peer->event, NULL);
159 }
160
161 int
proc_send(struct tmuxpeer * peer,enum msgtype type,int fd,const void * buf,size_t len)162 proc_send(struct tmuxpeer *peer, enum msgtype type, int fd, const void *buf,
163 size_t len)
164 {
165 struct imsgbuf *ibuf = &peer->ibuf;
166 void *vp = (void *)buf;
167 int retval;
168
169 if (peer->flags & PEER_BAD)
170 return (-1);
171 log_debug("sending message %d to peer %p (%zu bytes)", type, peer, len);
172
173 retval = imsg_compose(ibuf, type, PROTOCOL_VERSION, -1, fd, vp, len);
174 if (retval != 1)
175 return (-1);
176 proc_update_event(peer);
177 return (0);
178 }
179
180 struct tmuxproc *
proc_start(const char * name)181 proc_start(const char *name)
182 {
183 struct tmuxproc *tp;
184 struct utsname u;
185
186 log_open(name);
187 setproctitle("%s (%s)", name, socket_path);
188
189 if (uname(&u) < 0)
190 memset(&u, 0, sizeof u);
191
192 log_debug("%s started (%ld): version %s, socket %s, protocol %d", name,
193 (long)getpid(), getversion(), socket_path, PROTOCOL_VERSION);
194 log_debug("on %s %s %s; libevent %s (%s)", u.sysname, u.release,
195 u.version, event_get_version(), event_get_method());
196
197 tp = xcalloc(1, sizeof *tp);
198 tp->name = xstrdup(name);
199 TAILQ_INIT(&tp->peers);
200
201 return (tp);
202 }
203
204 void
proc_loop(struct tmuxproc * tp,int (* loopcb)(void))205 proc_loop(struct tmuxproc *tp, int (*loopcb)(void))
206 {
207 log_debug("%s loop enter", tp->name);
208 do
209 event_loop(EVLOOP_ONCE);
210 while (!tp->exit && (loopcb == NULL || !loopcb ()));
211 log_debug("%s loop exit", tp->name);
212 }
213
214 void
proc_exit(struct tmuxproc * tp)215 proc_exit(struct tmuxproc *tp)
216 {
217 struct tmuxpeer *peer;
218
219 TAILQ_FOREACH(peer, &tp->peers, entry)
220 imsgbuf_flush(&peer->ibuf);
221 tp->exit = 1;
222 }
223
224 void
proc_set_signals(struct tmuxproc * tp,void (* signalcb)(int))225 proc_set_signals(struct tmuxproc *tp, void (*signalcb)(int))
226 {
227 struct sigaction sa;
228
229 tp->signalcb = signalcb;
230
231 memset(&sa, 0, sizeof sa);
232 sigemptyset(&sa.sa_mask);
233 sa.sa_flags = SA_RESTART;
234 sa.sa_handler = SIG_IGN;
235
236 sigaction(SIGPIPE, &sa, NULL);
237 sigaction(SIGTSTP, &sa, NULL);
238 sigaction(SIGTTIN, &sa, NULL);
239 sigaction(SIGTTOU, &sa, NULL);
240 sigaction(SIGQUIT, &sa, NULL);
241
242 signal_set(&tp->ev_sigint, SIGINT, proc_signal_cb, tp);
243 signal_add(&tp->ev_sigint, NULL);
244 signal_set(&tp->ev_sighup, SIGHUP, proc_signal_cb, tp);
245 signal_add(&tp->ev_sighup, NULL);
246 signal_set(&tp->ev_sigchld, SIGCHLD, proc_signal_cb, tp);
247 signal_add(&tp->ev_sigchld, NULL);
248 signal_set(&tp->ev_sigcont, SIGCONT, proc_signal_cb, tp);
249 signal_add(&tp->ev_sigcont, NULL);
250 signal_set(&tp->ev_sigterm, SIGTERM, proc_signal_cb, tp);
251 signal_add(&tp->ev_sigterm, NULL);
252 signal_set(&tp->ev_sigusr1, SIGUSR1, proc_signal_cb, tp);
253 signal_add(&tp->ev_sigusr1, NULL);
254 signal_set(&tp->ev_sigusr2, SIGUSR2, proc_signal_cb, tp);
255 signal_add(&tp->ev_sigusr2, NULL);
256 signal_set(&tp->ev_sigwinch, SIGWINCH, proc_signal_cb, tp);
257 signal_add(&tp->ev_sigwinch, NULL);
258 }
259
260 void
proc_clear_signals(struct tmuxproc * tp,int defaults)261 proc_clear_signals(struct tmuxproc *tp, int defaults)
262 {
263 struct sigaction sa;
264
265 memset(&sa, 0, sizeof sa);
266 sigemptyset(&sa.sa_mask);
267 sa.sa_flags = SA_RESTART;
268 sa.sa_handler = SIG_DFL;
269
270 sigaction(SIGPIPE, &sa, NULL);
271 sigaction(SIGTSTP, &sa, NULL);
272
273 signal_del(&tp->ev_sigint);
274 signal_del(&tp->ev_sighup);
275 signal_del(&tp->ev_sigchld);
276 signal_del(&tp->ev_sigcont);
277 signal_del(&tp->ev_sigterm);
278 signal_del(&tp->ev_sigusr1);
279 signal_del(&tp->ev_sigusr2);
280 signal_del(&tp->ev_sigwinch);
281
282 if (defaults) {
283 sigaction(SIGINT, &sa, NULL);
284 sigaction(SIGQUIT, &sa, NULL);
285 sigaction(SIGHUP, &sa, NULL);
286 sigaction(SIGCHLD, &sa, NULL);
287 sigaction(SIGCONT, &sa, NULL);
288 sigaction(SIGTERM, &sa, NULL);
289 sigaction(SIGUSR1, &sa, NULL);
290 sigaction(SIGUSR2, &sa, NULL);
291 sigaction(SIGWINCH, &sa, NULL);
292 }
293 }
294
295 struct tmuxpeer *
proc_add_peer(struct tmuxproc * tp,int fd,void (* dispatchcb)(struct imsg *,void *),void * arg)296 proc_add_peer(struct tmuxproc *tp, int fd,
297 void (*dispatchcb)(struct imsg *, void *), void *arg)
298 {
299 struct tmuxpeer *peer;
300 gid_t gid;
301
302 peer = xcalloc(1, sizeof *peer);
303 peer->parent = tp;
304
305 peer->dispatchcb = dispatchcb;
306 peer->arg = arg;
307
308 if (imsgbuf_init(&peer->ibuf, fd) == -1)
309 fatal("imsgbuf_init");
310 imsgbuf_allow_fdpass(&peer->ibuf);
311 event_set(&peer->event, fd, EV_READ, proc_event_cb, peer);
312
313 if (getpeereid(fd, &peer->uid, &gid) != 0)
314 peer->uid = (uid_t)-1;
315
316 log_debug("add peer %p: %d (%p)", peer, fd, arg);
317 TAILQ_INSERT_TAIL(&tp->peers, peer, entry);
318
319 proc_update_event(peer);
320 return (peer);
321 }
322
323 void
proc_remove_peer(struct tmuxpeer * peer)324 proc_remove_peer(struct tmuxpeer *peer)
325 {
326 TAILQ_REMOVE(&peer->parent->peers, peer, entry);
327 log_debug("remove peer %p", peer);
328
329 event_del(&peer->event);
330 imsgbuf_clear(&peer->ibuf);
331
332 close(peer->ibuf.fd);
333 free(peer);
334 }
335
336 void
proc_kill_peer(struct tmuxpeer * peer)337 proc_kill_peer(struct tmuxpeer *peer)
338 {
339 peer->flags |= PEER_BAD;
340 }
341
342 void
proc_flush_peer(struct tmuxpeer * peer)343 proc_flush_peer(struct tmuxpeer *peer)
344 {
345 imsgbuf_flush(&peer->ibuf);
346 }
347
348 void
proc_toggle_log(struct tmuxproc * tp)349 proc_toggle_log(struct tmuxproc *tp)
350 {
351 log_toggle(tp->name);
352 }
353
354 pid_t
proc_fork_and_daemon(int * fd)355 proc_fork_and_daemon(int *fd)
356 {
357 pid_t pid;
358 int pair[2];
359
360 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
361 fatal("socketpair failed");
362 switch (pid = fork()) {
363 case -1:
364 fatal("fork failed");
365 case 0:
366 close(pair[0]);
367 *fd = pair[1];
368 if (daemon(1, 0) != 0)
369 fatal("daemon failed");
370 return (0);
371 default:
372 close(pair[1]);
373 *fd = pair[0];
374 return (pid);
375 }
376 }
377
378 uid_t
proc_get_peer_uid(struct tmuxpeer * peer)379 proc_get_peer_uid(struct tmuxpeer *peer)
380 {
381 return (peer->uid);
382 }
383