1 /* $OpenBSD: proc.c,v 1.24 2024/02/13 08:10:23 nicm 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 (((n = imsg_read(&peer->ibuf)) == -1 && errno != EAGAIN) ||
81 n == 0) {
82 peer->dispatchcb(NULL, peer->arg);
83 return;
84 }
85 for (;;) {
86 if ((n = imsg_get(&peer->ibuf, &imsg)) == -1) {
87 peer->dispatchcb(NULL, peer->arg);
88 return;
89 }
90 if (n == 0)
91 break;
92 log_debug("peer %p message %d", peer, imsg.hdr.type);
93
94 if (peer_check_version(peer, &imsg) != 0) {
95 fd = imsg_get_fd(&imsg);
96 if (fd != -1)
97 close(fd);
98 imsg_free(&imsg);
99 break;
100 }
101
102 peer->dispatchcb(&imsg, peer->arg);
103 imsg_free(&imsg);
104 }
105 }
106
107 if (events & EV_WRITE) {
108 if (msgbuf_write(&peer->ibuf.w) <= 0 && errno != EAGAIN) {
109 peer->dispatchcb(NULL, peer->arg);
110 return;
111 }
112 }
113
114 if ((peer->flags & PEER_BAD) && peer->ibuf.w.queued == 0) {
115 peer->dispatchcb(NULL, peer->arg);
116 return;
117 }
118
119 proc_update_event(peer);
120 }
121
122 static void
proc_signal_cb(int signo,__unused short events,void * arg)123 proc_signal_cb(int signo, __unused short events, void *arg)
124 {
125 struct tmuxproc *tp = arg;
126
127 tp->signalcb(signo);
128 }
129
130 static int
peer_check_version(struct tmuxpeer * peer,struct imsg * imsg)131 peer_check_version(struct tmuxpeer *peer, struct imsg *imsg)
132 {
133 int version;
134
135 version = imsg->hdr.peerid & 0xff;
136 if (imsg->hdr.type != MSG_VERSION && version != PROTOCOL_VERSION) {
137 log_debug("peer %p bad version %d", peer, version);
138
139 proc_send(peer, MSG_VERSION, -1, NULL, 0);
140 peer->flags |= PEER_BAD;
141
142 return (-1);
143 }
144 return (0);
145 }
146
147 static void
proc_update_event(struct tmuxpeer * peer)148 proc_update_event(struct tmuxpeer *peer)
149 {
150 short events;
151
152 event_del(&peer->event);
153
154 events = EV_READ;
155 if (peer->ibuf.w.queued > 0)
156 events |= EV_WRITE;
157 event_set(&peer->event, peer->ibuf.fd, events, proc_event_cb, peer);
158
159 event_add(&peer->event, NULL);
160 }
161
162 int
proc_send(struct tmuxpeer * peer,enum msgtype type,int fd,const void * buf,size_t len)163 proc_send(struct tmuxpeer *peer, enum msgtype type, int fd, const void *buf,
164 size_t len)
165 {
166 struct imsgbuf *ibuf = &peer->ibuf;
167 void *vp = (void *)buf;
168 int retval;
169
170 if (peer->flags & PEER_BAD)
171 return (-1);
172 log_debug("sending message %d to peer %p (%zu bytes)", type, peer, len);
173
174 retval = imsg_compose(ibuf, type, PROTOCOL_VERSION, -1, fd, vp, len);
175 if (retval != 1)
176 return (-1);
177 proc_update_event(peer);
178 return (0);
179 }
180
181 struct tmuxproc *
proc_start(const char * name)182 proc_start(const char *name)
183 {
184 struct tmuxproc *tp;
185 struct utsname u;
186
187 log_open(name);
188 setproctitle("%s (%s)", name, socket_path);
189
190 if (uname(&u) < 0)
191 memset(&u, 0, sizeof u);
192
193 log_debug("%s started (%ld): version %s, socket %s, protocol %d", name,
194 (long)getpid(), getversion(), socket_path, PROTOCOL_VERSION);
195 log_debug("on %s %s %s; libevent %s (%s)", u.sysname, u.release,
196 u.version, event_get_version(), event_get_method());
197
198 tp = xcalloc(1, sizeof *tp);
199 tp->name = xstrdup(name);
200 TAILQ_INIT(&tp->peers);
201
202 return (tp);
203 }
204
205 void
proc_loop(struct tmuxproc * tp,int (* loopcb)(void))206 proc_loop(struct tmuxproc *tp, int (*loopcb)(void))
207 {
208 log_debug("%s loop enter", tp->name);
209 do
210 event_loop(EVLOOP_ONCE);
211 while (!tp->exit && (loopcb == NULL || !loopcb ()));
212 log_debug("%s loop exit", tp->name);
213 }
214
215 void
proc_exit(struct tmuxproc * tp)216 proc_exit(struct tmuxproc *tp)
217 {
218 struct tmuxpeer *peer;
219
220 TAILQ_FOREACH(peer, &tp->peers, entry)
221 imsg_flush(&peer->ibuf);
222 tp->exit = 1;
223 }
224
225 void
proc_set_signals(struct tmuxproc * tp,void (* signalcb)(int))226 proc_set_signals(struct tmuxproc *tp, void (*signalcb)(int))
227 {
228 struct sigaction sa;
229
230 tp->signalcb = signalcb;
231
232 memset(&sa, 0, sizeof sa);
233 sigemptyset(&sa.sa_mask);
234 sa.sa_flags = SA_RESTART;
235 sa.sa_handler = SIG_IGN;
236
237 sigaction(SIGPIPE, &sa, NULL);
238 sigaction(SIGTSTP, &sa, NULL);
239 sigaction(SIGTTIN, &sa, NULL);
240 sigaction(SIGTTOU, &sa, NULL);
241 sigaction(SIGQUIT, &sa, NULL);
242
243 signal_set(&tp->ev_sigint, SIGINT, proc_signal_cb, tp);
244 signal_add(&tp->ev_sigint, NULL);
245 signal_set(&tp->ev_sighup, SIGHUP, proc_signal_cb, tp);
246 signal_add(&tp->ev_sighup, NULL);
247 signal_set(&tp->ev_sigchld, SIGCHLD, proc_signal_cb, tp);
248 signal_add(&tp->ev_sigchld, NULL);
249 signal_set(&tp->ev_sigcont, SIGCONT, proc_signal_cb, tp);
250 signal_add(&tp->ev_sigcont, NULL);
251 signal_set(&tp->ev_sigterm, SIGTERM, proc_signal_cb, tp);
252 signal_add(&tp->ev_sigterm, NULL);
253 signal_set(&tp->ev_sigusr1, SIGUSR1, proc_signal_cb, tp);
254 signal_add(&tp->ev_sigusr1, NULL);
255 signal_set(&tp->ev_sigusr2, SIGUSR2, proc_signal_cb, tp);
256 signal_add(&tp->ev_sigusr2, NULL);
257 signal_set(&tp->ev_sigwinch, SIGWINCH, proc_signal_cb, tp);
258 signal_add(&tp->ev_sigwinch, NULL);
259 }
260
261 void
proc_clear_signals(struct tmuxproc * tp,int defaults)262 proc_clear_signals(struct tmuxproc *tp, int defaults)
263 {
264 struct sigaction sa;
265
266 memset(&sa, 0, sizeof sa);
267 sigemptyset(&sa.sa_mask);
268 sa.sa_flags = SA_RESTART;
269 sa.sa_handler = SIG_DFL;
270
271 sigaction(SIGPIPE, &sa, NULL);
272 sigaction(SIGTSTP, &sa, NULL);
273
274 signal_del(&tp->ev_sigint);
275 signal_del(&tp->ev_sighup);
276 signal_del(&tp->ev_sigchld);
277 signal_del(&tp->ev_sigcont);
278 signal_del(&tp->ev_sigterm);
279 signal_del(&tp->ev_sigusr1);
280 signal_del(&tp->ev_sigusr2);
281 signal_del(&tp->ev_sigwinch);
282
283 if (defaults) {
284 sigaction(SIGINT, &sa, NULL);
285 sigaction(SIGQUIT, &sa, NULL);
286 sigaction(SIGHUP, &sa, NULL);
287 sigaction(SIGCHLD, &sa, NULL);
288 sigaction(SIGCONT, &sa, NULL);
289 sigaction(SIGTERM, &sa, NULL);
290 sigaction(SIGUSR1, &sa, NULL);
291 sigaction(SIGUSR2, &sa, NULL);
292 sigaction(SIGWINCH, &sa, NULL);
293 }
294 }
295
296 struct tmuxpeer *
proc_add_peer(struct tmuxproc * tp,int fd,void (* dispatchcb)(struct imsg *,void *),void * arg)297 proc_add_peer(struct tmuxproc *tp, int fd,
298 void (*dispatchcb)(struct imsg *, void *), void *arg)
299 {
300 struct tmuxpeer *peer;
301 gid_t gid;
302
303 peer = xcalloc(1, sizeof *peer);
304 peer->parent = tp;
305
306 peer->dispatchcb = dispatchcb;
307 peer->arg = arg;
308
309 imsg_init(&peer->ibuf, fd);
310 event_set(&peer->event, fd, EV_READ, proc_event_cb, peer);
311
312 if (getpeereid(fd, &peer->uid, &gid) != 0)
313 peer->uid = (uid_t)-1;
314
315 log_debug("add peer %p: %d (%p)", peer, fd, arg);
316 TAILQ_INSERT_TAIL(&tp->peers, peer, entry);
317
318 proc_update_event(peer);
319 return (peer);
320 }
321
322 void
proc_remove_peer(struct tmuxpeer * peer)323 proc_remove_peer(struct tmuxpeer *peer)
324 {
325 TAILQ_REMOVE(&peer->parent->peers, peer, entry);
326 log_debug("remove peer %p", peer);
327
328 event_del(&peer->event);
329 imsg_clear(&peer->ibuf);
330
331 close(peer->ibuf.fd);
332 free(peer);
333 }
334
335 void
proc_kill_peer(struct tmuxpeer * peer)336 proc_kill_peer(struct tmuxpeer *peer)
337 {
338 peer->flags |= PEER_BAD;
339 }
340
341 void
proc_flush_peer(struct tmuxpeer * peer)342 proc_flush_peer(struct tmuxpeer *peer)
343 {
344 imsg_flush(&peer->ibuf);
345 }
346
347 void
proc_toggle_log(struct tmuxproc * tp)348 proc_toggle_log(struct tmuxproc *tp)
349 {
350 log_toggle(tp->name);
351 }
352
353 pid_t
proc_fork_and_daemon(int * fd)354 proc_fork_and_daemon(int *fd)
355 {
356 pid_t pid;
357 int pair[2];
358
359 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
360 fatal("socketpair failed");
361 switch (pid = fork()) {
362 case -1:
363 fatal("fork failed");
364 case 0:
365 close(pair[0]);
366 *fd = pair[1];
367 if (daemon(1, 0) != 0)
368 fatal("daemon failed");
369 return (0);
370 default:
371 close(pair[1]);
372 *fd = pair[0];
373 return (pid);
374 }
375 }
376
377 uid_t
proc_get_peer_uid(struct tmuxpeer * peer)378 proc_get_peer_uid(struct tmuxpeer *peer)
379 {
380 return (peer->uid);
381 }
382