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1 | /* SPDX-License-Identifier: LGPL-2.1+ */ | |
2 | ||
3 | #include <netinet/tcp.h> | |
4 | ||
5 | #include "alloc-util.h" | |
6 | #include "fd-util.h" | |
7 | #include "io-util.h" | |
8 | #include "missing.h" | |
9 | #include "resolved-dns-stream.h" | |
10 | ||
11 | #define DNS_STREAM_TIMEOUT_USEC (10 * USEC_PER_SEC) | |
12 | #define DNS_STREAMS_MAX 128 | |
13 | ||
14 | static void dns_stream_stop(DnsStream *s) { | |
15 | assert(s); | |
16 | ||
17 | s->io_event_source = sd_event_source_unref(s->io_event_source); | |
18 | s->timeout_event_source = sd_event_source_unref(s->timeout_event_source); | |
19 | s->fd = safe_close(s->fd); | |
20 | } | |
21 | ||
22 | static int dns_stream_update_io(DnsStream *s) { | |
23 | int f = 0; | |
24 | ||
25 | assert(s); | |
26 | ||
27 | if (s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size) | |
28 | f |= EPOLLOUT; | |
29 | else if (!ordered_set_isempty(s->write_queue)) { | |
30 | dns_packet_unref(s->write_packet); | |
31 | s->write_packet = ordered_set_steal_first(s->write_queue); | |
32 | s->write_size = htobe16(s->write_packet->size); | |
33 | s->n_written = 0; | |
34 | f |= EPOLLOUT; | |
35 | } | |
36 | if (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size) | |
37 | f |= EPOLLIN; | |
38 | ||
39 | #if ENABLE_DNS_OVER_TLS | |
40 | /* For handshake and clean closing purposes, TLS can override requested events */ | |
41 | if (s->dnstls_events) | |
42 | f = s->dnstls_events; | |
43 | #endif | |
44 | ||
45 | return sd_event_source_set_io_events(s->io_event_source, f); | |
46 | } | |
47 | ||
48 | static int dns_stream_complete(DnsStream *s, int error) { | |
49 | assert(s); | |
50 | ||
51 | #if ENABLE_DNS_OVER_TLS | |
52 | if (s->encrypted) { | |
53 | int r; | |
54 | ||
55 | r = dnstls_stream_shutdown(s, error); | |
56 | if (r != -EAGAIN) | |
57 | dns_stream_stop(s); | |
58 | } else | |
59 | #endif | |
60 | dns_stream_stop(s); | |
61 | ||
62 | if (s->complete) | |
63 | s->complete(s, error); | |
64 | else /* the default action if no completion function is set is to close the stream */ | |
65 | dns_stream_unref(s); | |
66 | ||
67 | return 0; | |
68 | } | |
69 | ||
70 | static int dns_stream_identify(DnsStream *s) { | |
71 | union { | |
72 | struct cmsghdr header; /* For alignment */ | |
73 | uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo)) | |
74 | + EXTRA_CMSG_SPACE /* kernel appears to require extra space */]; | |
75 | } control; | |
76 | struct msghdr mh = {}; | |
77 | struct cmsghdr *cmsg; | |
78 | socklen_t sl; | |
79 | int r; | |
80 | ||
81 | assert(s); | |
82 | ||
83 | if (s->identified) | |
84 | return 0; | |
85 | ||
86 | /* Query the local side */ | |
87 | s->local_salen = sizeof(s->local); | |
88 | r = getsockname(s->fd, &s->local.sa, &s->local_salen); | |
89 | if (r < 0) | |
90 | return -errno; | |
91 | if (s->local.sa.sa_family == AF_INET6 && s->ifindex <= 0) | |
92 | s->ifindex = s->local.in6.sin6_scope_id; | |
93 | ||
94 | /* Query the remote side */ | |
95 | s->peer_salen = sizeof(s->peer); | |
96 | r = getpeername(s->fd, &s->peer.sa, &s->peer_salen); | |
97 | if (r < 0) | |
98 | return -errno; | |
99 | if (s->peer.sa.sa_family == AF_INET6 && s->ifindex <= 0) | |
100 | s->ifindex = s->peer.in6.sin6_scope_id; | |
101 | ||
102 | /* Check consistency */ | |
103 | assert(s->peer.sa.sa_family == s->local.sa.sa_family); | |
104 | assert(IN_SET(s->peer.sa.sa_family, AF_INET, AF_INET6)); | |
105 | ||
106 | /* Query connection meta information */ | |
107 | sl = sizeof(control); | |
108 | if (s->peer.sa.sa_family == AF_INET) { | |
109 | r = getsockopt(s->fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl); | |
110 | if (r < 0) | |
111 | return -errno; | |
112 | } else if (s->peer.sa.sa_family == AF_INET6) { | |
113 | ||
114 | r = getsockopt(s->fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl); | |
115 | if (r < 0) | |
116 | return -errno; | |
117 | } else | |
118 | return -EAFNOSUPPORT; | |
119 | ||
120 | mh.msg_control = &control; | |
121 | mh.msg_controllen = sl; | |
122 | ||
123 | CMSG_FOREACH(cmsg, &mh) { | |
124 | ||
125 | if (cmsg->cmsg_level == IPPROTO_IPV6) { | |
126 | assert(s->peer.sa.sa_family == AF_INET6); | |
127 | ||
128 | switch (cmsg->cmsg_type) { | |
129 | ||
130 | case IPV6_PKTINFO: { | |
131 | struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg); | |
132 | ||
133 | if (s->ifindex <= 0) | |
134 | s->ifindex = i->ipi6_ifindex; | |
135 | break; | |
136 | } | |
137 | ||
138 | case IPV6_HOPLIMIT: | |
139 | s->ttl = *(int *) CMSG_DATA(cmsg); | |
140 | break; | |
141 | } | |
142 | ||
143 | } else if (cmsg->cmsg_level == IPPROTO_IP) { | |
144 | assert(s->peer.sa.sa_family == AF_INET); | |
145 | ||
146 | switch (cmsg->cmsg_type) { | |
147 | ||
148 | case IP_PKTINFO: { | |
149 | struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg); | |
150 | ||
151 | if (s->ifindex <= 0) | |
152 | s->ifindex = i->ipi_ifindex; | |
153 | break; | |
154 | } | |
155 | ||
156 | case IP_TTL: | |
157 | s->ttl = *(int *) CMSG_DATA(cmsg); | |
158 | break; | |
159 | } | |
160 | } | |
161 | } | |
162 | ||
163 | /* The Linux kernel sets the interface index to the loopback | |
164 | * device if the connection came from the local host since it | |
165 | * avoids the routing table in such a case. Let's unset the | |
166 | * interface index in such a case. */ | |
167 | if (s->ifindex == LOOPBACK_IFINDEX) | |
168 | s->ifindex = 0; | |
169 | ||
170 | /* If we don't know the interface index still, we look for the | |
171 | * first local interface with a matching address. Yuck! */ | |
172 | if (s->ifindex <= 0) | |
173 | s->ifindex = manager_find_ifindex(s->manager, s->local.sa.sa_family, s->local.sa.sa_family == AF_INET ? (union in_addr_union*) &s->local.in.sin_addr : (union in_addr_union*) &s->local.in6.sin6_addr); | |
174 | ||
175 | if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) { | |
176 | uint32_t ifindex = htobe32(s->ifindex); | |
177 | ||
178 | /* Make sure all packets for this connection are sent on the same interface */ | |
179 | if (s->local.sa.sa_family == AF_INET) { | |
180 | r = setsockopt(s->fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex)); | |
181 | if (r < 0) | |
182 | log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF: %m"); | |
183 | } else if (s->local.sa.sa_family == AF_INET6) { | |
184 | r = setsockopt(s->fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex)); | |
185 | if (r < 0) | |
186 | log_debug_errno(errno, "Failed to invoke IPV6_UNICAST_IF: %m"); | |
187 | } | |
188 | } | |
189 | ||
190 | s->identified = true; | |
191 | ||
192 | return 0; | |
193 | } | |
194 | ||
195 | ssize_t dns_stream_writev(DnsStream *s, const struct iovec *iov, size_t iovcnt, int flags) { | |
196 | ssize_t r; | |
197 | ||
198 | assert(s); | |
199 | assert(iov); | |
200 | ||
201 | #if ENABLE_DNS_OVER_TLS | |
202 | if (s->encrypted && !(flags & DNS_STREAM_WRITE_TLS_DATA)) { | |
203 | ssize_t ss; | |
204 | size_t i; | |
205 | ||
206 | r = 0; | |
207 | for (i = 0; i < iovcnt; i++) { | |
208 | ss = dnstls_stream_write(s, iov[i].iov_base, iov[i].iov_len); | |
209 | if (ss < 0) | |
210 | return ss; | |
211 | ||
212 | r += ss; | |
213 | if (ss != (ssize_t) iov[i].iov_len) | |
214 | continue; | |
215 | } | |
216 | } else | |
217 | #endif | |
218 | if (s->tfo_salen > 0) { | |
219 | struct msghdr hdr = { | |
220 | .msg_iov = (struct iovec*) iov, | |
221 | .msg_iovlen = iovcnt, | |
222 | .msg_name = &s->tfo_address.sa, | |
223 | .msg_namelen = s->tfo_salen | |
224 | }; | |
225 | ||
226 | r = sendmsg(s->fd, &hdr, MSG_FASTOPEN); | |
227 | if (r < 0) { | |
228 | if (errno == EOPNOTSUPP) { | |
229 | s->tfo_salen = 0; | |
230 | r = connect(s->fd, &s->tfo_address.sa, s->tfo_salen); | |
231 | if (r < 0) | |
232 | return -errno; | |
233 | ||
234 | r = -EAGAIN; | |
235 | } else if (errno == EINPROGRESS) | |
236 | r = -EAGAIN; | |
237 | else | |
238 | r = -errno; | |
239 | } else | |
240 | s->tfo_salen = 0; /* connection is made */ | |
241 | } else { | |
242 | r = writev(s->fd, iov, iovcnt); | |
243 | if (r < 0) | |
244 | r = -errno; | |
245 | } | |
246 | ||
247 | return r; | |
248 | } | |
249 | ||
250 | static ssize_t dns_stream_read(DnsStream *s, void *buf, size_t count) { | |
251 | ssize_t ss; | |
252 | ||
253 | #if ENABLE_DNS_OVER_TLS | |
254 | if (s->encrypted) | |
255 | ss = dnstls_stream_read(s, buf, count); | |
256 | else | |
257 | #endif | |
258 | { | |
259 | ss = read(s->fd, buf, count); | |
260 | if (ss < 0) | |
261 | ss = -errno; | |
262 | } | |
263 | ||
264 | return ss; | |
265 | } | |
266 | ||
267 | static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) { | |
268 | DnsStream *s = userdata; | |
269 | ||
270 | assert(s); | |
271 | ||
272 | return dns_stream_complete(s, ETIMEDOUT); | |
273 | } | |
274 | ||
275 | static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *userdata) { | |
276 | DnsStream *s = userdata; | |
277 | int r; | |
278 | ||
279 | assert(s); | |
280 | ||
281 | #if ENABLE_DNS_OVER_TLS | |
282 | if (s->encrypted) { | |
283 | r = dnstls_stream_on_io(s, revents); | |
284 | ||
285 | if (r == DNSTLS_STREAM_CLOSED) | |
286 | return 0; | |
287 | else if (r == -EAGAIN) | |
288 | return dns_stream_update_io(s); | |
289 | else if (r < 0) { | |
290 | return dns_stream_complete(s, -r); | |
291 | } else { | |
292 | r = dns_stream_update_io(s); | |
293 | if (r < 0) | |
294 | return r; | |
295 | } | |
296 | } | |
297 | #endif | |
298 | ||
299 | /* only identify after connecting */ | |
300 | if (s->tfo_salen == 0) { | |
301 | r = dns_stream_identify(s); | |
302 | if (r < 0) | |
303 | return dns_stream_complete(s, -r); | |
304 | } | |
305 | ||
306 | if ((revents & EPOLLOUT) && | |
307 | s->write_packet && | |
308 | s->n_written < sizeof(s->write_size) + s->write_packet->size) { | |
309 | ||
310 | struct iovec iov[2]; | |
311 | ssize_t ss; | |
312 | ||
313 | iov[0].iov_base = &s->write_size; | |
314 | iov[0].iov_len = sizeof(s->write_size); | |
315 | iov[1].iov_base = DNS_PACKET_DATA(s->write_packet); | |
316 | iov[1].iov_len = s->write_packet->size; | |
317 | ||
318 | IOVEC_INCREMENT(iov, 2, s->n_written); | |
319 | ||
320 | ss = dns_stream_writev(s, iov, 2, 0); | |
321 | if (ss < 0) { | |
322 | if (!IN_SET(-ss, EINTR, EAGAIN)) | |
323 | return dns_stream_complete(s, -ss); | |
324 | } else | |
325 | s->n_written += ss; | |
326 | ||
327 | /* Are we done? If so, disable the event source for EPOLLOUT */ | |
328 | if (s->n_written >= sizeof(s->write_size) + s->write_packet->size) { | |
329 | r = dns_stream_update_io(s); | |
330 | if (r < 0) | |
331 | return dns_stream_complete(s, -r); | |
332 | } | |
333 | } | |
334 | ||
335 | if ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) && | |
336 | (!s->read_packet || | |
337 | s->n_read < sizeof(s->read_size) + s->read_packet->size)) { | |
338 | ||
339 | if (s->n_read < sizeof(s->read_size)) { | |
340 | ssize_t ss; | |
341 | ||
342 | ss = dns_stream_read(s, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read); | |
343 | if (ss < 0) { | |
344 | if (!IN_SET(-ss, EINTR, EAGAIN)) | |
345 | return dns_stream_complete(s, -ss); | |
346 | } else if (ss == 0) | |
347 | return dns_stream_complete(s, ECONNRESET); | |
348 | else | |
349 | s->n_read += ss; | |
350 | } | |
351 | ||
352 | if (s->n_read >= sizeof(s->read_size)) { | |
353 | ||
354 | if (be16toh(s->read_size) < DNS_PACKET_HEADER_SIZE) | |
355 | return dns_stream_complete(s, EBADMSG); | |
356 | ||
357 | if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) { | |
358 | ssize_t ss; | |
359 | ||
360 | if (!s->read_packet) { | |
361 | r = dns_packet_new(&s->read_packet, s->protocol, be16toh(s->read_size), DNS_PACKET_SIZE_MAX); | |
362 | if (r < 0) | |
363 | return dns_stream_complete(s, -r); | |
364 | ||
365 | s->read_packet->size = be16toh(s->read_size); | |
366 | s->read_packet->ipproto = IPPROTO_TCP; | |
367 | s->read_packet->family = s->peer.sa.sa_family; | |
368 | s->read_packet->ttl = s->ttl; | |
369 | s->read_packet->ifindex = s->ifindex; | |
370 | ||
371 | if (s->read_packet->family == AF_INET) { | |
372 | s->read_packet->sender.in = s->peer.in.sin_addr; | |
373 | s->read_packet->sender_port = be16toh(s->peer.in.sin_port); | |
374 | s->read_packet->destination.in = s->local.in.sin_addr; | |
375 | s->read_packet->destination_port = be16toh(s->local.in.sin_port); | |
376 | } else { | |
377 | assert(s->read_packet->family == AF_INET6); | |
378 | s->read_packet->sender.in6 = s->peer.in6.sin6_addr; | |
379 | s->read_packet->sender_port = be16toh(s->peer.in6.sin6_port); | |
380 | s->read_packet->destination.in6 = s->local.in6.sin6_addr; | |
381 | s->read_packet->destination_port = be16toh(s->local.in6.sin6_port); | |
382 | ||
383 | if (s->read_packet->ifindex == 0) | |
384 | s->read_packet->ifindex = s->peer.in6.sin6_scope_id; | |
385 | if (s->read_packet->ifindex == 0) | |
386 | s->read_packet->ifindex = s->local.in6.sin6_scope_id; | |
387 | } | |
388 | } | |
389 | ||
390 | ss = dns_stream_read(s, | |
391 | (uint8_t*) DNS_PACKET_DATA(s->read_packet) + s->n_read - sizeof(s->read_size), | |
392 | sizeof(s->read_size) + be16toh(s->read_size) - s->n_read); | |
393 | if (ss < 0) { | |
394 | if (!IN_SET(-ss, EINTR, EAGAIN)) | |
395 | return dns_stream_complete(s, -ss); | |
396 | } else if (ss == 0) | |
397 | return dns_stream_complete(s, ECONNRESET); | |
398 | else | |
399 | s->n_read += ss; | |
400 | } | |
401 | ||
402 | /* Are we done? If so, disable the event source for EPOLLIN */ | |
403 | if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) { | |
404 | /* If there's a packet handler | |
405 | * installed, call that. Note that | |
406 | * this is optional... */ | |
407 | if (s->on_packet) { | |
408 | r = s->on_packet(s); | |
409 | if (r < 0) | |
410 | return r; | |
411 | } | |
412 | ||
413 | r = dns_stream_update_io(s); | |
414 | if (r < 0) | |
415 | return dns_stream_complete(s, -r); | |
416 | } | |
417 | } | |
418 | } | |
419 | ||
420 | if ((s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) && | |
421 | (s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size)) | |
422 | return dns_stream_complete(s, 0); | |
423 | ||
424 | return 0; | |
425 | } | |
426 | ||
427 | DnsStream *dns_stream_unref(DnsStream *s) { | |
428 | DnsPacket *p; | |
429 | Iterator i; | |
430 | ||
431 | if (!s) | |
432 | return NULL; | |
433 | ||
434 | assert(s->n_ref > 0); | |
435 | s->n_ref--; | |
436 | ||
437 | if (s->n_ref > 0) | |
438 | return NULL; | |
439 | ||
440 | dns_stream_stop(s); | |
441 | ||
442 | if (s->server && s->server->stream == s) | |
443 | s->server->stream = NULL; | |
444 | ||
445 | if (s->manager) { | |
446 | LIST_REMOVE(streams, s->manager->dns_streams, s); | |
447 | s->manager->n_dns_streams--; | |
448 | } | |
449 | ||
450 | #if ENABLE_DNS_OVER_TLS | |
451 | if (s->encrypted) | |
452 | dnstls_stream_free(s); | |
453 | #endif | |
454 | ||
455 | ORDERED_SET_FOREACH(p, s->write_queue, i) | |
456 | dns_packet_unref(ordered_set_remove(s->write_queue, p)); | |
457 | ||
458 | dns_packet_unref(s->write_packet); | |
459 | dns_packet_unref(s->read_packet); | |
460 | dns_server_unref(s->server); | |
461 | ||
462 | ordered_set_free(s->write_queue); | |
463 | ||
464 | return mfree(s); | |
465 | } | |
466 | ||
467 | DnsStream *dns_stream_ref(DnsStream *s) { | |
468 | if (!s) | |
469 | return NULL; | |
470 | ||
471 | assert(s->n_ref > 0); | |
472 | s->n_ref++; | |
473 | ||
474 | return s; | |
475 | } | |
476 | ||
477 | int dns_stream_new(Manager *m, DnsStream **ret, DnsProtocol protocol, int fd, const union sockaddr_union *tfo_address) { | |
478 | _cleanup_(dns_stream_unrefp) DnsStream *s = NULL; | |
479 | int r; | |
480 | ||
481 | assert(m); | |
482 | assert(fd >= 0); | |
483 | ||
484 | if (m->n_dns_streams > DNS_STREAMS_MAX) | |
485 | return -EBUSY; | |
486 | ||
487 | s = new0(DnsStream, 1); | |
488 | if (!s) | |
489 | return -ENOMEM; | |
490 | ||
491 | r = ordered_set_ensure_allocated(&s->write_queue, &dns_packet_hash_ops); | |
492 | if (r < 0) | |
493 | return r; | |
494 | ||
495 | s->n_ref = 1; | |
496 | s->fd = -1; | |
497 | s->protocol = protocol; | |
498 | ||
499 | r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s); | |
500 | if (r < 0) | |
501 | return r; | |
502 | ||
503 | (void) sd_event_source_set_description(s->io_event_source, "dns-stream-io"); | |
504 | ||
505 | r = sd_event_add_time( | |
506 | m->event, | |
507 | &s->timeout_event_source, | |
508 | clock_boottime_or_monotonic(), | |
509 | now(clock_boottime_or_monotonic()) + DNS_STREAM_TIMEOUT_USEC, 0, | |
510 | on_stream_timeout, s); | |
511 | if (r < 0) | |
512 | return r; | |
513 | ||
514 | (void) sd_event_source_set_description(s->timeout_event_source, "dns-stream-timeout"); | |
515 | ||
516 | LIST_PREPEND(streams, m->dns_streams, s); | |
517 | s->manager = m; | |
518 | s->fd = fd; | |
519 | if (tfo_address) { | |
520 | s->tfo_address = *tfo_address; | |
521 | s->tfo_salen = tfo_address->sa.sa_family == AF_INET6 ? sizeof(tfo_address->in6) : sizeof(tfo_address->in); | |
522 | } | |
523 | ||
524 | m->n_dns_streams++; | |
525 | ||
526 | *ret = TAKE_PTR(s); | |
527 | ||
528 | return 0; | |
529 | } | |
530 | ||
531 | int dns_stream_write_packet(DnsStream *s, DnsPacket *p) { | |
532 | int r; | |
533 | ||
534 | assert(s); | |
535 | ||
536 | r = ordered_set_put(s->write_queue, p); | |
537 | if (r < 0) | |
538 | return r; | |
539 | ||
540 | dns_packet_ref(p); | |
541 | ||
542 | return dns_stream_update_io(s); | |
543 | } |