2 * Copyright (c) 2022 Stefan Sperling <stsp@openbsd.org>
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 #include <sys/types.h>
18 #include <sys/queue.h>
19 #include <sys/socket.h>
34 #include "got_error.h"
42 #define nitems(_a) (sizeof((_a)) / sizeof((_a)[0]))
45 struct gotd_listen_client {
46 STAILQ_ENTRY(gotd_listen_client) entry;
51 STAILQ_HEAD(gotd_listen_clients, gotd_listen_client);
53 static struct gotd_listen_clients gotd_listen_clients[GOTD_CLIENT_TABLE_SIZE];
54 static SIPHASH_KEY clients_hash_key;
55 static volatile int listen_client_cnt;
58 struct gotd_uid_connection_counter {
59 STAILQ_ENTRY(gotd_uid_connection_counter) entry;
63 STAILQ_HEAD(gotd_client_uids, gotd_uid_connection_counter);
64 static struct gotd_client_uids gotd_client_uids[GOTD_CLIENT_TABLE_SIZE];
65 static SIPHASH_KEY uid_hash_key;
71 struct gotd_imsgev iev;
72 struct gotd_imsgev pause;
73 struct gotd_uid_connection_limit *connection_limits;
74 size_t nconnection_limits;
79 static void listen_shutdown(void);
82 listen_sighdlr(int sig, short event, void *arg)
85 * Normal signal handler rules don't apply because libevent
100 fatalx("unexpected signal");
105 client_hash(uint32_t client_id)
107 return SipHash24(&clients_hash_key, &client_id, sizeof(client_id));
111 add_client(struct gotd_listen_client *client)
113 uint64_t slot = client_hash(client->id) % nitems(gotd_listen_clients);
114 STAILQ_INSERT_HEAD(&gotd_listen_clients[slot], client, entry);
118 static struct gotd_listen_client *
119 find_client(uint32_t client_id)
122 struct gotd_listen_client *c;
124 slot = client_hash(client_id) % nitems(gotd_listen_clients);
125 STAILQ_FOREACH(c, &gotd_listen_clients[slot], entry) {
126 if (c->id == client_id)
141 duplicate = (find_client(id) != NULL);
142 } while (duplicate || id == 0);
150 return SipHash24(&uid_hash_key, &euid, sizeof(euid));
154 add_uid_connection_counter(struct gotd_uid_connection_counter *counter)
156 uint64_t slot = uid_hash(counter->euid) % nitems(gotd_client_uids);
157 STAILQ_INSERT_HEAD(&gotd_client_uids[slot], counter, entry);
161 remove_uid_connection_counter(struct gotd_uid_connection_counter *counter)
163 uint64_t slot = uid_hash(counter->euid) % nitems(gotd_client_uids);
164 STAILQ_REMOVE(&gotd_client_uids[slot], counter,
165 gotd_uid_connection_counter, entry);
168 static struct gotd_uid_connection_counter *
169 find_uid_connection_counter(uid_t euid)
172 struct gotd_uid_connection_counter *c;
174 slot = uid_hash(euid) % nitems(gotd_client_uids);
175 STAILQ_FOREACH(c, &gotd_client_uids[slot], entry) {
183 static const struct got_error *
184 disconnect(struct gotd_listen_client *client)
186 struct gotd_uid_connection_counter *counter;
190 log_debug("client on fd %d disconnecting", client->fd);
192 slot = client_hash(client->id) % nitems(gotd_listen_clients);
193 STAILQ_REMOVE(&gotd_listen_clients[slot], client,
194 gotd_listen_client, entry);
196 counter = find_uid_connection_counter(client->euid);
198 if (counter->nconnections > 0)
199 counter->nconnections--;
200 if (counter->nconnections == 0) {
201 remove_uid_connection_counter(counter);
206 client_fd = client->fd;
210 if (close(client_fd) == -1)
211 return got_error_from_errno("close");
217 accept_reserve(int fd, struct sockaddr *addr, socklen_t *addrlen,
218 int reserve, volatile int *counter)
222 if (getdtablecount() + reserve +
223 ((*counter + 1) * GOTD_FD_NEEDED) >= getdtablesize()) {
224 log_debug("inflight fds exceeded");
229 if ((ret = accept4(fd, addr, addrlen,
230 SOCK_NONBLOCK | SOCK_CLOEXEC)) > -1) {
238 gotd_accept_paused(int fd, short event, void *arg)
240 event_add(&gotd_listen.iev.ev, NULL);
244 gotd_accept(int fd, short event, void *arg)
246 struct gotd_imsgev *iev = arg;
247 struct sockaddr_storage ss;
248 struct timeval backoff;
251 struct gotd_listen_client *client = NULL;
252 struct gotd_uid_connection_counter *counter = NULL;
253 struct gotd_imsg_connect iconn;
260 if (event_add(&gotd_listen.iev.ev, NULL) == -1) {
261 log_warn("event_add");
264 if (event & EV_TIMEOUT)
269 /* Other backoff conditions apart from EMFILE/ENFILE? */
270 s = accept_reserve(fd, (struct sockaddr *)&ss, &len, GOTD_FD_RESERVE,
280 event_del(&gotd_listen.iev.ev);
281 evtimer_add(&gotd_listen.pause.ev, &backoff);
289 if (listen_client_cnt >= GOTD_MAXCLIENTS)
292 if (getpeereid(s, &euid, &egid) == -1) {
293 log_warn("getpeerid");
297 counter = find_uid_connection_counter(euid);
298 if (counter == NULL) {
299 counter = calloc(1, sizeof(*counter));
300 if (counter == NULL) {
301 log_warn("%s: calloc", __func__);
304 counter->euid = euid;
305 counter->nconnections = 1;
306 add_uid_connection_counter(counter);
308 int max_connections = GOTD_MAX_CONN_PER_UID;
309 struct gotd_uid_connection_limit *limit;
311 limit = gotd_find_uid_connection_limit(
312 gotd_listen.connection_limits,
313 gotd_listen.nconnection_limits, euid);
315 max_connections = limit->max_connections;
317 if (counter->nconnections >= max_connections) {
318 log_warnx("maximum connections exceeded for uid %d",
322 counter->nconnections++;
325 client = calloc(1, sizeof(*client));
326 if (client == NULL) {
327 log_warn("%s: calloc", __func__);
330 client->id = get_client_id();
335 log_debug("%s: new client connected on fd %d uid %d gid %d", __func__,
336 client->fd, euid, egid);
338 memset(&iconn, 0, sizeof(iconn));
339 iconn.client_id = client->id;
344 log_warn("%s: dup", __func__);
347 if (gotd_imsg_compose_event(iev, GOTD_IMSG_CONNECT, PROC_LISTEN, s,
348 &iconn, sizeof(iconn)) == -1) {
349 log_warn("imsg compose CONNECT");
362 static const struct got_error *
363 recv_disconnect(struct imsg *imsg)
365 struct gotd_imsg_disconnect idisconnect;
367 struct gotd_listen_client *client = NULL;
369 datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
370 if (datalen != sizeof(idisconnect))
371 return got_error(GOT_ERR_PRIVSEP_LEN);
372 memcpy(&idisconnect, imsg->data, sizeof(idisconnect));
374 log_debug("client disconnecting");
376 client = find_client(idisconnect.client_id);
378 return got_error(GOT_ERR_CLIENT_ID);
380 return disconnect(client);
384 listen_dispatch(int fd, short event, void *arg)
386 const struct got_error *err = NULL;
387 struct gotd_imsgev *iev = arg;
388 struct imsgbuf *ibuf = &iev->ibuf;
393 if (event & EV_READ) {
394 if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
395 fatal("imsg_read error");
396 if (n == 0) /* Connection closed. */
400 if (event & EV_WRITE) {
401 n = msgbuf_write(&ibuf->w);
402 if (n == -1 && errno != EAGAIN)
403 fatal("msgbuf_write");
404 if (n == 0) /* Connection closed. */
409 if ((n = imsg_get(ibuf, &imsg)) == -1)
410 fatal("%s: imsg_get", __func__);
411 if (n == 0) /* No more messages. */
414 switch (imsg.hdr.type) {
415 case GOTD_IMSG_DISCONNECT:
416 err = recv_disconnect(&imsg);
418 log_warnx("disconnect: %s", err->msg);
421 log_debug("unexpected imsg %d", imsg.hdr.type);
429 gotd_imsg_event_add(iev);
431 /* This pipe is dead. Remove its event handler */
433 event_loopexit(NULL);
438 listen_main(const char *title, int gotd_socket,
439 struct gotd_uid_connection_limit *connection_limits,
440 size_t nconnection_limits)
442 struct gotd_imsgev iev;
443 struct event evsigint, evsigterm, evsighup, evsigusr1;
445 arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
446 arc4random_buf(&uid_hash_key, sizeof(uid_hash_key));
448 gotd_listen.title = title;
449 gotd_listen.pid = getpid();
450 gotd_listen.fd = gotd_socket;
451 gotd_listen.connection_limits = connection_limits;
452 gotd_listen.nconnection_limits = nconnection_limits;
454 signal_set(&evsigint, SIGINT, listen_sighdlr, NULL);
455 signal_set(&evsigterm, SIGTERM, listen_sighdlr, NULL);
456 signal_set(&evsighup, SIGHUP, listen_sighdlr, NULL);
457 signal_set(&evsigusr1, SIGUSR1, listen_sighdlr, NULL);
458 signal(SIGPIPE, SIG_IGN);
460 signal_add(&evsigint, NULL);
461 signal_add(&evsigterm, NULL);
462 signal_add(&evsighup, NULL);
463 signal_add(&evsigusr1, NULL);
465 imsg_init(&iev.ibuf, GOTD_FILENO_MSG_PIPE);
466 iev.handler = listen_dispatch;
467 iev.events = EV_READ;
468 iev.handler_arg = NULL;
469 event_set(&iev.ev, iev.ibuf.fd, EV_READ, listen_dispatch, &iev);
470 if (event_add(&iev.ev, NULL) == -1)
473 event_set(&gotd_listen.iev.ev, gotd_listen.fd, EV_READ | EV_PERSIST,
475 if (event_add(&gotd_listen.iev.ev, NULL))
477 evtimer_set(&gotd_listen.pause.ev, gotd_accept_paused, NULL);
485 listen_shutdown(void)
487 log_debug("shutting down");
489 free(gotd_listen.connection_limits);
490 if (gotd_listen.fd != -1)
491 close(gotd_listen.fd);