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>
35 #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 struct gotd_uid_connection_limit *
184 gotd_find_uid_connection_limit(struct gotd_uid_connection_limit *limits,
185 size_t nlimits, uid_t uid)
187 /* This array is always sorted to allow for binary search. */
188 int i, left = 0, right = nlimits - 1;
190 while (left <= right) {
191 i = ((left + right) / 2);
192 if (limits[i].uid == uid)
194 if (limits[i].uid > uid)
203 static const struct got_error *
204 disconnect(struct gotd_listen_client *client)
206 struct gotd_uid_connection_counter *counter;
210 log_debug("client on fd %d disconnecting", client->fd);
212 slot = client_hash(client->id) % nitems(gotd_listen_clients);
213 STAILQ_REMOVE(&gotd_listen_clients[slot], client,
214 gotd_listen_client, entry);
216 counter = find_uid_connection_counter(client->euid);
218 if (counter->nconnections > 0)
219 counter->nconnections--;
220 if (counter->nconnections == 0) {
221 remove_uid_connection_counter(counter);
226 client_fd = client->fd;
230 if (close(client_fd) == -1)
231 return got_error_from_errno("close");
237 accept_reserve(int fd, struct sockaddr *addr, socklen_t *addrlen,
238 int reserve, volatile int *counter)
242 if (getdtablecount() + reserve +
243 ((*counter + 1) * GOTD_FD_NEEDED) >= getdtablesize()) {
244 log_debug("inflight fds exceeded");
249 if ((ret = accept4(fd, addr, addrlen,
250 SOCK_NONBLOCK | SOCK_CLOEXEC)) > -1) {
258 gotd_accept_paused(int fd, short event, void *arg)
260 event_add(&gotd_listen.iev.ev, NULL);
264 gotd_accept(int fd, short event, void *arg)
266 struct gotd_imsgev *iev = arg;
267 struct sockaddr_storage ss;
268 struct timeval backoff;
271 struct gotd_listen_client *client = NULL;
272 struct gotd_uid_connection_counter *counter = NULL;
273 struct gotd_imsg_connect iconn;
280 if (event_add(&gotd_listen.iev.ev, NULL) == -1) {
281 log_warn("event_add");
284 if (event & EV_TIMEOUT)
289 /* Other backoff conditions apart from EMFILE/ENFILE? */
290 s = accept_reserve(fd, (struct sockaddr *)&ss, &len, GOTD_FD_RESERVE,
300 event_del(&gotd_listen.iev.ev);
301 evtimer_add(&gotd_listen.pause.ev, &backoff);
309 if (listen_client_cnt >= GOTD_MAXCLIENTS)
312 if (getpeereid(s, &euid, &egid) == -1) {
313 log_warn("getpeerid");
317 counter = find_uid_connection_counter(euid);
318 if (counter == NULL) {
319 counter = calloc(1, sizeof(*counter));
320 if (counter == NULL) {
321 log_warn("%s: calloc", __func__);
324 counter->euid = euid;
325 counter->nconnections = 1;
326 add_uid_connection_counter(counter);
328 int max_connections = GOTD_MAX_CONN_PER_UID;
329 struct gotd_uid_connection_limit *limit;
331 limit = gotd_find_uid_connection_limit(
332 gotd_listen.connection_limits,
333 gotd_listen.nconnection_limits, euid);
335 max_connections = limit->max_connections;
337 if (counter->nconnections >= max_connections) {
338 log_warnx("maximum connections exceeded for uid %d",
342 counter->nconnections++;
345 client = calloc(1, sizeof(*client));
346 if (client == NULL) {
347 log_warn("%s: calloc", __func__);
350 client->id = get_client_id();
355 log_debug("%s: new client connected on fd %d uid %d gid %d", __func__,
356 client->fd, euid, egid);
358 memset(&iconn, 0, sizeof(iconn));
359 iconn.client_id = client->id;
364 log_warn("%s: dup", __func__);
367 if (gotd_imsg_compose_event(iev, GOTD_IMSG_CONNECT, PROC_LISTEN, s,
368 &iconn, sizeof(iconn)) == -1) {
369 log_warn("imsg compose CONNECT");
382 static const struct got_error *
383 recv_disconnect(struct imsg *imsg)
385 struct gotd_imsg_disconnect idisconnect;
387 struct gotd_listen_client *client = NULL;
389 datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
390 if (datalen != sizeof(idisconnect))
391 return got_error(GOT_ERR_PRIVSEP_LEN);
392 memcpy(&idisconnect, imsg->data, sizeof(idisconnect));
394 log_debug("client disconnecting");
396 client = find_client(idisconnect.client_id);
398 return got_error(GOT_ERR_CLIENT_ID);
400 return disconnect(client);
404 listen_dispatch(int fd, short event, void *arg)
406 const struct got_error *err = NULL;
407 struct gotd_imsgev *iev = arg;
408 struct imsgbuf *ibuf = &iev->ibuf;
413 if (event & EV_READ) {
414 if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
415 fatal("imsg_read error");
416 if (n == 0) /* Connection closed. */
420 if (event & EV_WRITE) {
421 n = msgbuf_write(&ibuf->w);
422 if (n == -1 && errno != EAGAIN)
423 fatal("msgbuf_write");
424 if (n == 0) /* Connection closed. */
429 if ((n = imsg_get(ibuf, &imsg)) == -1)
430 fatal("%s: imsg_get", __func__);
431 if (n == 0) /* No more messages. */
434 switch (imsg.hdr.type) {
435 case GOTD_IMSG_DISCONNECT:
436 err = recv_disconnect(&imsg);
438 log_warnx("%s: disconnect: %s",
439 gotd_listen.title, err->msg);
442 log_debug("%s: unexpected imsg %d", gotd_listen.title,
451 gotd_imsg_event_add(iev);
453 /* This pipe is dead. Remove its event handler */
455 event_loopexit(NULL);
460 listen_main(const char *title, int gotd_socket,
461 struct gotd_uid_connection_limit *connection_limits,
462 size_t nconnection_limits)
464 struct gotd_imsgev iev;
465 struct event evsigint, evsigterm, evsighup, evsigusr1;
467 arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
468 arc4random_buf(&uid_hash_key, sizeof(uid_hash_key));
470 gotd_listen.title = title;
471 gotd_listen.pid = getpid();
472 gotd_listen.fd = gotd_socket;
473 gotd_listen.connection_limits = connection_limits;
474 gotd_listen.nconnection_limits = nconnection_limits;
476 signal_set(&evsigint, SIGINT, listen_sighdlr, NULL);
477 signal_set(&evsigterm, SIGTERM, listen_sighdlr, NULL);
478 signal_set(&evsighup, SIGHUP, listen_sighdlr, NULL);
479 signal_set(&evsigusr1, SIGUSR1, listen_sighdlr, NULL);
480 signal(SIGPIPE, SIG_IGN);
482 signal_add(&evsigint, NULL);
483 signal_add(&evsigterm, NULL);
484 signal_add(&evsighup, NULL);
485 signal_add(&evsigusr1, NULL);
487 imsg_init(&iev.ibuf, GOTD_FILENO_MSG_PIPE);
488 iev.handler = listen_dispatch;
489 iev.events = EV_READ;
490 iev.handler_arg = NULL;
491 event_set(&iev.ev, iev.ibuf.fd, EV_READ, listen_dispatch, &iev);
492 if (event_add(&iev.ev, NULL) == -1)
495 event_set(&gotd_listen.iev.ev, gotd_listen.fd, EV_READ | EV_PERSIST,
497 if (event_add(&gotd_listen.iev.ev, NULL))
499 evtimer_set(&gotd_listen.pause.ev, gotd_accept_paused, NULL);
507 listen_shutdown(void)
509 log_debug("%s: shutting down", gotd_listen.title);
511 free(gotd_listen.connection_limits);
512 if (gotd_listen.fd != -1)
513 close(gotd_listen.fd);