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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
b30bf55d | 2 | |
ca8b62b5 | 3 | #include <net/if_arp.h> |
8624f128 | 4 | #include <netinet/tcp.h> |
ca8b62b5 | 5 | |
4ff9bc2e | 6 | #include "errno-util.h" |
b30bf55d | 7 | #include "fd-util.h" |
ef118d00 | 8 | #include "missing_network.h" |
af8b1384 | 9 | #include "missing_socket.h" |
b30bf55d | 10 | #include "resolved-dns-stub.h" |
1f05101f | 11 | #include "socket-netlink.h" |
b30bf55d | 12 | #include "socket-util.h" |
4a6eb824 | 13 | #include "stdio-util.h" |
ae8f0ec3 | 14 | #include "string-table.h" |
b30bf55d LP |
15 | |
16 | /* The MTU of the loopback device is 64K on Linux, advertise that as maximum datagram size, but subtract the Ethernet, | |
17 | * IP and UDP header sizes */ | |
18 | #define ADVERTISE_DATAGRAM_SIZE_MAX (65536U-14U-20U-8U) | |
19 | ||
b370adb5 LP |
20 | /* On the extra stubs, use a more conservative choice */ |
21 | #define ADVERTISE_EXTRA_DATAGRAM_SIZE_MAX DNS_PACKET_UNICAST_SIZE_LARGE_MAX | |
22 | ||
b5febb3f | 23 | static int manager_dns_stub_fd_extra(Manager *m, DnsStubListenerExtra *l, int type); |
0354029b | 24 | |
ae8f0ec3 LP |
25 | static void dns_stub_listener_extra_hash_func(const DnsStubListenerExtra *a, struct siphash *state) { |
26 | assert(a); | |
27 | ||
28 | siphash24_compress(&a->mode, sizeof(a->mode), state); | |
29 | siphash24_compress(&a->family, sizeof(a->family), state); | |
30 | siphash24_compress(&a->address, FAMILY_ADDRESS_SIZE(a->family), state); | |
31 | siphash24_compress(&a->port, sizeof(a->port), state); | |
32 | } | |
33 | ||
34 | static int dns_stub_listener_extra_compare_func(const DnsStubListenerExtra *a, const DnsStubListenerExtra *b) { | |
35 | int r; | |
36 | ||
37 | assert(a); | |
38 | assert(b); | |
39 | ||
40 | r = CMP(a->mode, b->mode); | |
41 | if (r != 0) | |
42 | return r; | |
43 | ||
44 | r = CMP(a->family, b->family); | |
45 | if (r != 0) | |
46 | return r; | |
47 | ||
48 | r = memcmp(&a->address, &b->address, FAMILY_ADDRESS_SIZE(a->family)); | |
49 | if (r != 0) | |
50 | return r; | |
51 | ||
52 | return CMP(a->port, b->port); | |
53 | } | |
54 | ||
55 | DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR( | |
56 | dns_stub_listener_extra_hash_ops, | |
57 | DnsStubListenerExtra, | |
58 | dns_stub_listener_extra_hash_func, | |
59 | dns_stub_listener_extra_compare_func, | |
60 | dns_stub_listener_extra_free); | |
61 | ||
0354029b LP |
62 | int dns_stub_listener_extra_new( |
63 | Manager *m, | |
64 | DnsStubListenerExtra **ret) { | |
ae8f0ec3 | 65 | |
36aaabc3 | 66 | DnsStubListenerExtra *l; |
1f05101f | 67 | |
0354029b | 68 | l = new(DnsStubListenerExtra, 1); |
1f05101f SS |
69 | if (!l) |
70 | return -ENOMEM; | |
71 | ||
0354029b LP |
72 | *l = (DnsStubListenerExtra) { |
73 | .manager = m, | |
74 | }; | |
1f05101f | 75 | |
0354029b | 76 | *ret = TAKE_PTR(l); |
1f05101f SS |
77 | return 0; |
78 | } | |
79 | ||
36aaabc3 | 80 | DnsStubListenerExtra *dns_stub_listener_extra_free(DnsStubListenerExtra *p) { |
bf22f231 YW |
81 | if (!p) |
82 | return NULL; | |
83 | ||
84 | p->udp_event_source = sd_event_source_unref(p->udp_event_source); | |
85 | p->tcp_event_source = sd_event_source_unref(p->tcp_event_source); | |
bf22f231 | 86 | |
bde69bbd LP |
87 | hashmap_free(p->queries_by_packet); |
88 | ||
bf22f231 YW |
89 | return mfree(p); |
90 | } | |
91 | ||
bde69bbd LP |
92 | static void stub_packet_hash_func(const DnsPacket *p, struct siphash *state) { |
93 | assert(p); | |
94 | ||
95 | siphash24_compress(&p->protocol, sizeof(p->protocol), state); | |
96 | siphash24_compress(&p->family, sizeof(p->family), state); | |
97 | siphash24_compress(&p->sender, sizeof(p->sender), state); | |
98 | siphash24_compress(&p->ipproto, sizeof(p->ipproto), state); | |
99 | siphash24_compress(&p->sender_port, sizeof(p->sender_port), state); | |
100 | siphash24_compress(DNS_PACKET_HEADER(p), sizeof(DnsPacketHeader), state); | |
101 | ||
102 | /* We don't bother hashing the full packet here, just the header */ | |
103 | } | |
104 | ||
105 | static int stub_packet_compare_func(const DnsPacket *x, const DnsPacket *y) { | |
106 | int r; | |
107 | ||
108 | r = CMP(x->protocol, y->protocol); | |
109 | if (r != 0) | |
110 | return r; | |
111 | ||
112 | r = CMP(x->family, y->family); | |
113 | if (r != 0) | |
114 | return r; | |
115 | ||
116 | r = memcmp(&x->sender, &y->sender, sizeof(x->sender)); | |
117 | if (r != 0) | |
118 | return r; | |
119 | ||
120 | r = CMP(x->ipproto, y->ipproto); | |
121 | if (r != 0) | |
122 | return r; | |
123 | ||
124 | r = CMP(x->sender_port, y->sender_port); | |
125 | if (r != 0) | |
126 | return r; | |
127 | ||
128 | return memcmp(DNS_PACKET_HEADER(x), DNS_PACKET_HEADER(y), sizeof(DnsPacketHeader)); | |
129 | } | |
130 | ||
131 | DEFINE_HASH_OPS(stub_packet_hash_ops, DnsPacket, stub_packet_hash_func, stub_packet_compare_func); | |
132 | ||
5bd7ebb3 LP |
133 | static int reply_add_with_rrsig( |
134 | DnsAnswer **reply, | |
135 | DnsResourceRecord *rr, | |
136 | int ifindex, | |
137 | DnsAnswerFlags flags, | |
138 | DnsResourceRecord *rrsig, | |
139 | bool with_rrsig) { | |
140 | int r; | |
141 | ||
142 | assert(reply); | |
143 | assert(rr); | |
144 | ||
145 | r = dns_answer_add_extend(reply, rr, ifindex, flags, rrsig); | |
146 | if (r < 0) | |
147 | return r; | |
148 | ||
149 | if (with_rrsig && rrsig) { | |
150 | r = dns_answer_add_extend(reply, rrsig, ifindex, flags, NULL); | |
151 | if (r < 0) | |
152 | return r; | |
153 | } | |
154 | ||
155 | return 0; | |
156 | } | |
157 | ||
775ae354 LP |
158 | static int dns_stub_collect_answer_by_question( |
159 | DnsAnswer **reply, | |
51027656 | 160 | DnsAnswer *answer, |
775ae354 LP |
161 | DnsQuestion *question, |
162 | bool with_rrsig) { /* Add RRSIG RR matching each RR */ | |
b30bf55d | 163 | |
5bd7ebb3 | 164 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *redirected_key = NULL; |
775ae354 | 165 | DnsAnswerItem *item; |
b30bf55d LP |
166 | int r; |
167 | ||
775ae354 | 168 | assert(reply); |
e8d23f92 | 169 | |
775ae354 | 170 | /* Copies all RRs from 'answer' into 'reply', if they match 'question'. */ |
b30bf55d | 171 | |
775ae354 | 172 | DNS_ANSWER_FOREACH_ITEM(item, answer) { |
775ae354 | 173 | if (question) { |
775ae354 LP |
174 | r = dns_question_matches_rr(question, item->rr, NULL); |
175 | if (r < 0) | |
176 | return r; | |
5bd7ebb3 LP |
177 | if (r == 0) { |
178 | _cleanup_free_ char *target = NULL; | |
179 | ||
180 | /* OK, so the RR doesn't directly match. Let's see if the RR is a matching | |
181 | * CNAME or DNAME */ | |
182 | ||
183 | r = dns_resource_record_get_cname_target( | |
184 | question->keys[0], | |
185 | item->rr, | |
186 | &target); | |
187 | if (r == -EUNATCH) | |
188 | continue; /* Not a CNAME/DNAME or doesn't match */ | |
775ae354 LP |
189 | if (r < 0) |
190 | return r; | |
775ae354 | 191 | |
5bd7ebb3 LP |
192 | dns_resource_key_unref(redirected_key); |
193 | ||
194 | /* There can only be one CNAME per name, hence no point in storing more than one here */ | |
195 | redirected_key = dns_resource_key_new(question->keys[0]->class, question->keys[0]->type, target); | |
196 | if (!redirected_key) | |
197 | return -ENOMEM; | |
198 | } | |
775ae354 LP |
199 | } |
200 | ||
5bd7ebb3 LP |
201 | /* Mask the section info, we want the primary answers to always go without section info, so |
202 | * that it is added to the answer section when we synthesize a reply. */ | |
203 | ||
204 | r = reply_add_with_rrsig( | |
205 | reply, | |
206 | item->rr, | |
207 | item->ifindex, | |
208 | item->flags & ~DNS_ANSWER_MASK_SECTIONS, | |
209 | item->rrsig, | |
210 | with_rrsig); | |
e8d23f92 LP |
211 | if (r < 0) |
212 | return r; | |
5bd7ebb3 | 213 | } |
b30bf55d | 214 | |
5bd7ebb3 LP |
215 | if (!redirected_key) |
216 | return 0; | |
217 | ||
218 | /* This is a CNAME/DNAME answer. In this case also append where the redirections point to to the main | |
219 | * answer section */ | |
220 | ||
221 | DNS_ANSWER_FOREACH_ITEM(item, answer) { | |
222 | ||
223 | r = dns_resource_key_match_rr(redirected_key, item->rr, NULL); | |
224 | if (r < 0) | |
225 | return r; | |
226 | if (r == 0) | |
227 | continue; | |
228 | ||
229 | r = reply_add_with_rrsig( | |
230 | reply, | |
231 | item->rr, | |
232 | item->ifindex, | |
233 | item->flags & ~DNS_ANSWER_MASK_SECTIONS, | |
234 | item->rrsig, | |
235 | with_rrsig); | |
236 | if (r < 0) | |
237 | return r; | |
e8d23f92 | 238 | } |
b30bf55d | 239 | |
775ae354 LP |
240 | return 0; |
241 | } | |
e8d23f92 | 242 | |
775ae354 LP |
243 | static int dns_stub_collect_answer_by_section( |
244 | DnsAnswer **reply, | |
245 | DnsAnswer *answer, | |
246 | DnsAnswerFlags section, | |
247 | DnsAnswer *exclude1, | |
248 | DnsAnswer *exclude2, | |
249 | bool with_dnssec) { /* Include DNSSEC RRs. RRSIG, NSEC, … */ | |
b30bf55d | 250 | |
775ae354 | 251 | DnsAnswerItem *item; |
775ae354 | 252 | int r; |
b30bf55d | 253 | |
775ae354 LP |
254 | assert(reply); |
255 | ||
256 | /* Copies all RRs from 'answer' into 'reply', if they originate from the specified section. Also, | |
257 | * avoid any RRs listed in 'exclude'. */ | |
258 | ||
259 | DNS_ANSWER_FOREACH_ITEM(item, answer) { | |
260 | ||
261 | if (dns_answer_contains(exclude1, item->rr) || | |
262 | dns_answer_contains(exclude2, item->rr)) | |
263 | continue; | |
264 | ||
265 | if (!with_dnssec && | |
266 | dns_type_is_dnssec(item->rr->key->type)) | |
267 | continue; | |
268 | ||
269 | if (((item->flags ^ section) & (DNS_ANSWER_SECTION_ANSWER|DNS_ANSWER_SECTION_AUTHORITY|DNS_ANSWER_SECTION_ADDITIONAL)) != 0) | |
270 | continue; | |
271 | ||
5bd7ebb3 LP |
272 | r = reply_add_with_rrsig( |
273 | reply, | |
274 | item->rr, | |
275 | item->ifindex, | |
276 | item->flags, | |
277 | item->rrsig, | |
278 | with_dnssec); | |
b30bf55d LP |
279 | if (r < 0) |
280 | return r; | |
b30bf55d | 281 | } |
e8d23f92 | 282 | |
5bd7ebb3 | 283 | return 0; |
775ae354 LP |
284 | } |
285 | ||
286 | static int dns_stub_assign_sections( | |
287 | DnsQuery *q, | |
288 | DnsQuestion *question, | |
289 | bool edns0_do) { | |
290 | ||
291 | int r; | |
292 | ||
293 | assert(q); | |
294 | assert(question); | |
295 | ||
c6ebf89b LP |
296 | /* Let's assign the 'answer' RRs we collected to their respective sections in the reply datagram. We |
297 | * try to reproduce a section assignment similar to what the upstream DNS server responded to us. We | |
298 | * use the DNS_ANSWER_SECTION_xyz flags to match things up, which is where the original upstream's | |
299 | * packet section assignment is stored in the DnsAnswer object. Not all RRs in the 'answer' objects | |
300 | * come with section information though (for example, because they were synthesized locally, and not | |
301 | * from a DNS packet). To deal with that we extend the assignment logic a bit: anything from the | |
302 | * 'answer' object that directly matches the original question is always put in the ANSWER section, | |
303 | * regardless if it carries section info, or what that section info says. Then, anything from the | |
304 | * 'answer' objects that is from the ANSWER or AUTHORITY sections, and wasn't already added to the | |
305 | * ANSWER section is placed in the AUTHORITY section. Everything else from either object is added to | |
306 | * the ADDITIONAL section. */ | |
775ae354 LP |
307 | |
308 | /* Include all RRs that directly answer the question in the answer section */ | |
309 | r = dns_stub_collect_answer_by_question( | |
310 | &q->reply_answer, | |
311 | q->answer, | |
312 | question, | |
313 | edns0_do); | |
314 | if (r < 0) | |
315 | return r; | |
316 | ||
317 | /* Include all RRs that originate from the answer or authority sections, and aren't listed in the | |
318 | * answer section, in the authority section */ | |
319 | r = dns_stub_collect_answer_by_section( | |
320 | &q->reply_authoritative, | |
321 | q->answer, | |
322 | DNS_ANSWER_SECTION_ANSWER, | |
323 | q->reply_answer, NULL, | |
324 | edns0_do); | |
325 | if (r < 0) | |
326 | return r; | |
775ae354 LP |
327 | r = dns_stub_collect_answer_by_section( |
328 | &q->reply_authoritative, | |
329 | q->answer, | |
330 | DNS_ANSWER_SECTION_AUTHORITY, | |
331 | q->reply_answer, NULL, | |
332 | edns0_do); | |
333 | if (r < 0) | |
334 | return r; | |
335 | ||
336 | /* Include all RRs that originate from the additional sections in the additional section (except if | |
337 | * already listed in the other two sections). Also add all RRs with no section marking. */ | |
338 | r = dns_stub_collect_answer_by_section( | |
339 | &q->reply_additional, | |
340 | q->answer, | |
341 | DNS_ANSWER_SECTION_ADDITIONAL, | |
342 | q->reply_answer, q->reply_authoritative, | |
343 | edns0_do); | |
344 | if (r < 0) | |
345 | return r; | |
346 | r = dns_stub_collect_answer_by_section( | |
347 | &q->reply_additional, | |
348 | q->answer, | |
349 | 0, | |
350 | q->reply_answer, q->reply_authoritative, | |
351 | edns0_do); | |
352 | if (r < 0) | |
353 | return r; | |
354 | ||
355 | return 0; | |
356 | } | |
357 | ||
358 | static int dns_stub_make_reply_packet( | |
359 | DnsPacket **ret, | |
360 | size_t max_size, | |
361 | DnsQuestion *q, | |
362 | bool *ret_truncated) { | |
363 | ||
364 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
365 | bool tc = false; | |
366 | int r; | |
367 | ||
368 | assert(ret); | |
369 | ||
370 | r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0, max_size); | |
371 | if (r < 0) | |
372 | return r; | |
373 | ||
374 | r = dns_packet_append_question(p, q); | |
375 | if (r == -EMSGSIZE) | |
376 | tc = true; | |
377 | else if (r < 0) | |
378 | return r; | |
379 | ||
51027656 | 380 | if (ret_truncated) |
775ae354 LP |
381 | *ret_truncated = tc; |
382 | else if (tc) | |
51027656 LP |
383 | return -EMSGSIZE; |
384 | ||
775ae354 | 385 | DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q)); |
e8d23f92 | 386 | |
775ae354 LP |
387 | *ret = TAKE_PTR(p); |
388 | return 0; | |
389 | } | |
390 | ||
391 | static int dns_stub_add_reply_packet_body( | |
392 | DnsPacket *p, | |
393 | DnsAnswer *answer, | |
394 | DnsAnswer *authoritative, | |
395 | DnsAnswer *additional, | |
396 | bool edns0_do, /* Client expects DNSSEC RRs? */ | |
397 | bool *truncated) { | |
398 | ||
399 | unsigned n_answer = 0, n_authoritative = 0, n_additional = 0; | |
400 | bool tc = false; | |
401 | int r; | |
402 | ||
403 | assert(p); | |
404 | ||
405 | /* Add the three sections to the packet. If the answer section doesn't fit we'll signal that as | |
406 | * truncation. If the authoritative section doesn't fit and we are in DNSSEC mode, also signal | |
407 | * truncation. In all other cases where things don't fit don't signal truncation, as for those cases | |
408 | * the dropped RRs should not be essential. */ | |
409 | ||
410 | r = dns_packet_append_answer(p, answer, &n_answer); | |
411 | if (r == -EMSGSIZE) | |
412 | tc = true; | |
413 | else if (r < 0) | |
414 | return r; | |
415 | else { | |
416 | r = dns_packet_append_answer(p, authoritative, &n_authoritative); | |
417 | if (r == -EMSGSIZE) { | |
418 | if (edns0_do) | |
419 | tc = true; | |
420 | } else if (r < 0) | |
421 | return r; | |
422 | else { | |
423 | r = dns_packet_append_answer(p, additional, &n_additional); | |
424 | if (r < 0 && r != -EMSGSIZE) | |
425 | return r; | |
426 | } | |
427 | } | |
428 | ||
429 | if (tc) { | |
430 | if (!truncated) | |
431 | return -EMSGSIZE; | |
432 | ||
433 | *truncated = true; | |
434 | } | |
435 | ||
436 | DNS_PACKET_HEADER(p)->ancount = htobe16(n_answer); | |
437 | DNS_PACKET_HEADER(p)->nscount = htobe16(n_authoritative); | |
438 | DNS_PACKET_HEADER(p)->arcount = htobe16(n_additional); | |
e8d23f92 LP |
439 | return 0; |
440 | } | |
441 | ||
4a6eb824 LP |
442 | static const char *nsid_string(void) { |
443 | static char buffer[SD_ID128_STRING_MAX + STRLEN(".resolved.systemd.io")] = ""; | |
444 | sd_id128_t id; | |
445 | int r; | |
446 | ||
447 | /* Let's generate a string that we can use as RFC5001 NSID identifier. The string shall identify us | |
448 | * as systemd-resolved, and return a different string for each resolved instance without leaking host | |
449 | * identity. Hence let's use a fixed suffix that identifies resolved, and a prefix generated from the | |
450 | * machine ID but from which the machine ID cannot be determined. | |
451 | * | |
452 | * Clients can use this to determine whether an answer is originating locally or is proxied from | |
453 | * upstream. */ | |
454 | ||
455 | if (!isempty(buffer)) | |
456 | return buffer; | |
457 | ||
458 | r = sd_id128_get_machine_app_specific( | |
459 | SD_ID128_MAKE(ed,d3,12,5d,16,b9,41,f9,a1,49,5f,ab,15,62,ab,27), | |
460 | &id); | |
461 | if (r < 0) { | |
b480543c | 462 | log_debug_errno(r, "Failed to determine machine ID, ignoring: %m"); |
4a6eb824 LP |
463 | return NULL; |
464 | } | |
465 | ||
466 | xsprintf(buffer, SD_ID128_FORMAT_STR ".resolved.systemd.io", SD_ID128_FORMAT_VAL(id)); | |
467 | return buffer; | |
468 | } | |
469 | ||
e8d23f92 LP |
470 | static int dns_stub_finish_reply_packet( |
471 | DnsPacket *p, | |
472 | uint16_t id, | |
473 | int rcode, | |
51027656 | 474 | bool tc, /* set the Truncated bit? */ |
4ad017cd | 475 | bool aa, /* set the Authoritative Answer bit? */ |
e8d23f92 LP |
476 | bool add_opt, /* add an OPT RR to this packet? */ |
477 | bool edns0_do, /* set the EDNS0 DNSSEC OK bit? */ | |
b370adb5 | 478 | bool ad, /* set the DNSSEC authenticated data bit? */ |
775ae354 | 479 | bool cd, /* set the DNSSEC checking disabled bit? */ |
4a6eb824 LP |
480 | uint16_t max_udp_size, /* The maximum UDP datagram size to advertise to clients */ |
481 | bool nsid) { /* whether to add NSID */ | |
e8d23f92 LP |
482 | |
483 | int r; | |
484 | ||
485 | assert(p); | |
486 | ||
ff4caaae | 487 | if (add_opt) { |
4a6eb824 | 488 | r = dns_packet_append_opt(p, max_udp_size, edns0_do, /* include_rfc6975 = */ false, nsid ? nsid_string() : NULL, rcode, NULL); |
ff4caaae LP |
489 | if (r == -EMSGSIZE) /* Hit the size limit? then indicate truncation */ |
490 | tc = true; | |
491 | else if (r < 0) | |
492 | return r; | |
ff4caaae | 493 | } else { |
941dd294 LP |
494 | /* If the client can't to EDNS0, don't do DO either */ |
495 | edns0_do = false; | |
496 | ||
775ae354 | 497 | /* If we don't do EDNS, clamp the rcode to 4 bit */ |
941dd294 LP |
498 | if (rcode > 0xF) |
499 | rcode = DNS_RCODE_SERVFAIL; | |
500 | } | |
501 | ||
8c9c68b5 LP |
502 | /* Don't set the CD bit unless DO is on, too */ |
503 | if (!edns0_do) | |
775ae354 LP |
504 | cd = false; |
505 | ||
8c9c68b5 LP |
506 | /* Note that we allow the AD bit to be set even if client didn't signal DO, as per RFC 6840, section |
507 | * 5.7 */ | |
e8d23f92 LP |
508 | |
509 | DNS_PACKET_HEADER(p)->id = id; | |
510 | ||
511 | DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( | |
51027656 LP |
512 | 1 /* qr */, |
513 | 0 /* opcode */, | |
4ad017cd | 514 | aa /* aa */, |
51027656 LP |
515 | tc /* tc */, |
516 | 1 /* rd */, | |
517 | 1 /* ra */, | |
e8d23f92 | 518 | ad /* ad */, |
775ae354 | 519 | cd /* cd */, |
e8d23f92 | 520 | rcode)); |
b30bf55d | 521 | |
b30bf55d LP |
522 | return 0; |
523 | } | |
524 | ||
0354029b LP |
525 | static int dns_stub_send( |
526 | Manager *m, | |
527 | DnsStubListenerExtra *l, | |
528 | DnsStream *s, | |
529 | DnsPacket *p, | |
530 | DnsPacket *reply) { | |
531 | ||
b30bf55d LP |
532 | int r; |
533 | ||
534 | assert(m); | |
535 | assert(p); | |
536 | assert(reply); | |
537 | ||
538 | if (s) | |
539 | r = dns_stream_write_packet(s, reply); | |
0354029b | 540 | else |
b30bf55d LP |
541 | /* Note that it is essential here that we explicitly choose the source IP address for this packet. This |
542 | * is because otherwise the kernel will choose it automatically based on the routing table and will | |
543 | * thus pick 127.0.0.1 rather than 127.0.0.53. */ | |
0354029b | 544 | r = manager_send(m, |
b5febb3f | 545 | manager_dns_stub_fd_extra(m, l, SOCK_DGRAM), |
0354029b LP |
546 | l ? p->ifindex : LOOPBACK_IFINDEX, /* force loopback iface if this is the main listener stub */ |
547 | p->family, &p->sender, p->sender_port, &p->destination, | |
548 | reply); | |
b30bf55d LP |
549 | if (r < 0) |
550 | return log_debug_errno(r, "Failed to send reply packet: %m"); | |
551 | ||
552 | return 0; | |
553 | } | |
554 | ||
775ae354 LP |
555 | static int dns_stub_send_reply( |
556 | DnsQuery *q, | |
557 | int rcode) { | |
558 | ||
559 | _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; | |
560 | bool truncated, edns0_do; | |
561 | int r; | |
562 | ||
563 | assert(q); | |
564 | ||
565 | /* Reply with DNSSEC DO set? Only if client supports it; and we did any DNSSEC verification | |
566 | * ourselves, or consider the data fully authenticated because we generated it locally, or | |
567 | * the client set cd */ | |
568 | edns0_do = | |
569 | DNS_PACKET_DO(q->request_packet) && | |
570 | (q->answer_dnssec_result >= 0 || /* we did proper DNSSEC validation … */ | |
571 | dns_query_fully_authenticated(q) || /* … or we considered it authentic otherwise … */ | |
572 | DNS_PACKET_CD(q->request_packet)); /* … or client set CD */ | |
573 | ||
574 | r = dns_stub_assign_sections( | |
575 | q, | |
576 | q->request_packet->question, | |
577 | edns0_do); | |
578 | if (r < 0) | |
579 | return log_debug_errno(r, "Failed to assign sections: %m"); | |
580 | ||
581 | r = dns_stub_make_reply_packet( | |
582 | &reply, | |
583 | DNS_PACKET_PAYLOAD_SIZE_MAX(q->request_packet), | |
584 | q->request_packet->question, | |
585 | &truncated); | |
586 | if (r < 0) | |
587 | return log_debug_errno(r, "Failed to build reply packet: %m"); | |
588 | ||
589 | r = dns_stub_add_reply_packet_body( | |
590 | reply, | |
591 | q->reply_answer, | |
592 | q->reply_authoritative, | |
593 | q->reply_additional, | |
594 | edns0_do, | |
595 | &truncated); | |
596 | if (r < 0) | |
597 | return log_debug_errno(r, "Failed to append reply packet body: %m"); | |
598 | ||
599 | r = dns_stub_finish_reply_packet( | |
600 | reply, | |
601 | DNS_PACKET_ID(q->request_packet), | |
602 | rcode, | |
603 | truncated, | |
4ad017cd | 604 | dns_query_fully_synthetic(q), |
775ae354 LP |
605 | !!q->request_packet->opt, |
606 | edns0_do, | |
8c9c68b5 | 607 | DNS_PACKET_AD(q->request_packet) && dns_query_fully_authenticated(q), |
775ae354 | 608 | DNS_PACKET_CD(q->request_packet), |
4a6eb824 LP |
609 | q->stub_listener_extra ? ADVERTISE_EXTRA_DATAGRAM_SIZE_MAX : ADVERTISE_DATAGRAM_SIZE_MAX, |
610 | dns_packet_has_nsid_request(q->request_packet) > 0 && !q->stub_listener_extra); | |
775ae354 LP |
611 | if (r < 0) |
612 | return log_debug_errno(r, "Failed to build failure packet: %m"); | |
613 | ||
614 | return dns_stub_send(q->manager, q->stub_listener_extra, q->request_stream, q->request_packet, reply); | |
615 | } | |
616 | ||
0354029b LP |
617 | static int dns_stub_send_failure( |
618 | Manager *m, | |
619 | DnsStubListenerExtra *l, | |
620 | DnsStream *s, | |
621 | DnsPacket *p, | |
622 | int rcode, | |
623 | bool authenticated) { | |
624 | ||
b30bf55d | 625 | _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; |
775ae354 | 626 | bool truncated; |
b30bf55d LP |
627 | int r; |
628 | ||
629 | assert(m); | |
630 | assert(p); | |
631 | ||
775ae354 LP |
632 | r = dns_stub_make_reply_packet( |
633 | &reply, | |
634 | DNS_PACKET_PAYLOAD_SIZE_MAX(p), | |
635 | p->question, | |
636 | &truncated); | |
e8d23f92 LP |
637 | if (r < 0) |
638 | return log_debug_errno(r, "Failed to make failure packet: %m"); | |
639 | ||
b370adb5 LP |
640 | r = dns_stub_finish_reply_packet( |
641 | reply, | |
642 | DNS_PACKET_ID(p), | |
643 | rcode, | |
775ae354 | 644 | truncated, |
4ad017cd | 645 | false, |
b370adb5 LP |
646 | !!p->opt, |
647 | DNS_PACKET_DO(p), | |
8c9c68b5 | 648 | DNS_PACKET_AD(p) && authenticated, |
775ae354 | 649 | DNS_PACKET_CD(p), |
4a6eb824 LP |
650 | l ? ADVERTISE_EXTRA_DATAGRAM_SIZE_MAX : ADVERTISE_DATAGRAM_SIZE_MAX, |
651 | dns_packet_has_nsid_request(p) > 0 && !l); | |
b30bf55d LP |
652 | if (r < 0) |
653 | return log_debug_errno(r, "Failed to build failure packet: %m"); | |
654 | ||
0354029b | 655 | return dns_stub_send(m, l, s, p, reply); |
b30bf55d LP |
656 | } |
657 | ||
775ae354 LP |
658 | static int dns_stub_patch_bypass_reply_packet( |
659 | DnsPacket **ret, /* Where to place the patched packet */ | |
660 | DnsPacket *original, /* The packet to patch */ | |
661 | DnsPacket *request) { /* The packet the patched packet shall look like a reply to */ | |
662 | _cleanup_(dns_packet_unrefp) DnsPacket *c = NULL; | |
663 | int r; | |
664 | ||
665 | assert(ret); | |
666 | assert(original); | |
667 | assert(request); | |
668 | ||
669 | r = dns_packet_dup(&c, original); | |
670 | if (r < 0) | |
671 | return r; | |
672 | ||
673 | /* Extract the packet, so that we know where the OPT field is */ | |
674 | r = dns_packet_extract(c); | |
675 | if (r < 0) | |
676 | return r; | |
677 | ||
678 | /* Copy over the original client request ID, so that we can make the upstream query look like our own reply. */ | |
679 | DNS_PACKET_HEADER(c)->id = DNS_PACKET_HEADER(request)->id; | |
680 | ||
681 | /* Patch in our own maximum datagram size, if EDNS0 was on */ | |
682 | r = dns_packet_patch_max_udp_size(c, ADVERTISE_DATAGRAM_SIZE_MAX); | |
683 | if (r < 0) | |
684 | return r; | |
685 | ||
686 | /* Lower all TTLs by the time passed since we received the datagram. */ | |
687 | if (timestamp_is_set(original->timestamp)) { | |
688 | r = dns_packet_patch_ttls(c, original->timestamp); | |
689 | if (r < 0) | |
690 | return r; | |
691 | } | |
692 | ||
693 | /* Our upstream connection might have supported larger DNS requests than our downstream one, hence | |
694 | * set the TC bit if our reply is larger than what the client supports, and truncate. */ | |
695 | if (c->size > DNS_PACKET_PAYLOAD_SIZE_MAX(request)) { | |
696 | log_debug("Artificially truncating stub response, as advertised size of client is smaller than upstream one."); | |
697 | dns_packet_truncate(c, DNS_PACKET_PAYLOAD_SIZE_MAX(request)); | |
698 | DNS_PACKET_HEADER(c)->flags = htobe16(be16toh(DNS_PACKET_HEADER(c)->flags) | DNS_PACKET_FLAG_TC); | |
699 | } | |
700 | ||
701 | *ret = TAKE_PTR(c); | |
702 | return 0; | |
703 | } | |
704 | ||
b30bf55d LP |
705 | static void dns_stub_query_complete(DnsQuery *q) { |
706 | int r; | |
707 | ||
708 | assert(q); | |
775ae354 | 709 | assert(q->request_packet); |
b30bf55d | 710 | |
775ae354 LP |
711 | if (q->question_bypass) { |
712 | /* This is a bypass reply. If so, let's propagate the upstream packet, if we have it and it | |
713 | * is regular DNS. (We can't do this if the upstream packet is LLMNR or mDNS, since the | |
714 | * packets are not 100% compatible.) */ | |
b30bf55d | 715 | |
775ae354 LP |
716 | if (q->answer_full_packet && |
717 | q->answer_full_packet->protocol == DNS_PROTOCOL_DNS) { | |
718 | _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; | |
e8d23f92 | 719 | |
775ae354 LP |
720 | r = dns_stub_patch_bypass_reply_packet(&reply, q->answer_full_packet, q->request_packet); |
721 | if (r < 0) | |
722 | log_debug_errno(r, "Failed to patch bypass reply packet: %m"); | |
723 | else | |
724 | (void) dns_stub_send(q->manager, q->stub_listener_extra, q->request_stream, q->request_packet, reply); | |
725 | ||
726 | dns_query_free(q); | |
727 | return; | |
e8d23f92 | 728 | } |
775ae354 | 729 | } |
b30bf55d | 730 | |
2f4d8e57 LP |
731 | /* Note that we don't bother with following CNAMEs here. We propagate the authoritative/additional |
732 | * sections from the upstream answer however, hence if the upstream server collected that information | |
733 | * already we don't have to collect it ourselves anymore. */ | |
734 | ||
775ae354 LP |
735 | switch (q->state) { |
736 | ||
737 | case DNS_TRANSACTION_SUCCESS: | |
b30bf55d | 738 | case DNS_TRANSACTION_RCODE_FAILURE: |
775ae354 | 739 | (void) dns_stub_send_reply(q, q->answer_rcode); |
b30bf55d LP |
740 | break; |
741 | ||
742 | case DNS_TRANSACTION_NOT_FOUND: | |
775ae354 | 743 | (void) dns_stub_send_reply(q, DNS_RCODE_NXDOMAIN); |
b30bf55d LP |
744 | break; |
745 | ||
746 | case DNS_TRANSACTION_TIMEOUT: | |
747 | case DNS_TRANSACTION_ATTEMPTS_MAX_REACHED: | |
748 | /* Propagate a timeout as a no packet, i.e. that the client also gets a timeout */ | |
749 | break; | |
750 | ||
751 | case DNS_TRANSACTION_NO_SERVERS: | |
752 | case DNS_TRANSACTION_INVALID_REPLY: | |
753 | case DNS_TRANSACTION_ERRNO: | |
754 | case DNS_TRANSACTION_ABORTED: | |
755 | case DNS_TRANSACTION_DNSSEC_FAILED: | |
756 | case DNS_TRANSACTION_NO_TRUST_ANCHOR: | |
757 | case DNS_TRANSACTION_RR_TYPE_UNSUPPORTED: | |
758 | case DNS_TRANSACTION_NETWORK_DOWN: | |
775ae354 | 759 | case DNS_TRANSACTION_NO_SOURCE: |
49ef064c | 760 | case DNS_TRANSACTION_STUB_LOOP: |
775ae354 | 761 | (void) dns_stub_send_reply(q, DNS_RCODE_SERVFAIL); |
b30bf55d LP |
762 | break; |
763 | ||
764 | case DNS_TRANSACTION_NULL: | |
765 | case DNS_TRANSACTION_PENDING: | |
766 | case DNS_TRANSACTION_VALIDATING: | |
767 | default: | |
768 | assert_not_reached("Impossible state"); | |
769 | } | |
770 | ||
b30bf55d LP |
771 | dns_query_free(q); |
772 | } | |
773 | ||
774 | static int dns_stub_stream_complete(DnsStream *s, int error) { | |
775 | assert(s); | |
776 | ||
b412af57 LP |
777 | log_debug_errno(error, "DNS TCP connection terminated, destroying queries: %m"); |
778 | ||
779 | for (;;) { | |
780 | DnsQuery *q; | |
781 | ||
782 | q = set_first(s->queries); | |
783 | if (!q) | |
784 | break; | |
b30bf55d | 785 | |
b412af57 LP |
786 | dns_query_free(q); |
787 | } | |
b30bf55d | 788 | |
b412af57 LP |
789 | /* This drops the implicit ref we keep around since it was allocated, as incoming stub connections |
790 | * should be kept as long as the client wants to. */ | |
791 | dns_stream_unref(s); | |
b30bf55d LP |
792 | return 0; |
793 | } | |
794 | ||
0354029b | 795 | static void dns_stub_process_query(Manager *m, DnsStubListenerExtra *l, DnsStream *s, DnsPacket *p) { |
ceb17827 | 796 | _cleanup_(dns_query_freep) DnsQuery *q = NULL; |
bde69bbd LP |
797 | Hashmap **queries_by_packet; |
798 | DnsQuery *existing; | |
b30bf55d LP |
799 | int r; |
800 | ||
801 | assert(m); | |
802 | assert(p); | |
803 | assert(p->protocol == DNS_PROTOCOL_DNS); | |
804 | ||
0354029b | 805 | if (!l && /* l == NULL if this is the main stub */ |
d1fb8cda YW |
806 | (in_addr_is_localhost(p->family, &p->sender) <= 0 || |
807 | in_addr_is_localhost(p->family, &p->destination) <= 0)) { | |
565147b7 | 808 | log_warning("Got packet on unexpected (i.e. non-localhost) IP range, ignoring."); |
ceb17827 | 809 | return; |
b30bf55d LP |
810 | } |
811 | ||
a9fd8837 LP |
812 | if (manager_packet_from_our_transaction(m, p)) { |
813 | log_debug("Got our own packet looped back, ignoring."); | |
814 | return; | |
815 | } | |
816 | ||
bde69bbd LP |
817 | queries_by_packet = l ? &l->queries_by_packet : &m->stub_queries_by_packet; |
818 | existing = hashmap_get(*queries_by_packet, p); | |
819 | if (existing && dns_packet_equal(existing->request_packet, p)) { | |
820 | log_debug("Got repeat packet from client, ignoring."); | |
821 | return; | |
822 | } | |
823 | ||
b30bf55d LP |
824 | r = dns_packet_extract(p); |
825 | if (r < 0) { | |
826 | log_debug_errno(r, "Failed to extract resources from incoming packet, ignoring packet: %m"); | |
0354029b | 827 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_FORMERR, false); |
ceb17827 | 828 | return; |
b30bf55d LP |
829 | } |
830 | ||
831 | if (!DNS_PACKET_VERSION_SUPPORTED(p)) { | |
832 | log_debug("Got EDNS OPT field with unsupported version number."); | |
0354029b | 833 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_BADVERS, false); |
ceb17827 | 834 | return; |
b30bf55d LP |
835 | } |
836 | ||
837 | if (dns_type_is_obsolete(p->question->keys[0]->type)) { | |
838 | log_debug("Got message with obsolete key type, refusing."); | |
30ee7071 | 839 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_REFUSED, false); |
ceb17827 | 840 | return; |
b30bf55d LP |
841 | } |
842 | ||
843 | if (dns_type_is_zone_transer(p->question->keys[0]->type)) { | |
844 | log_debug("Got request for zone transfer, refusing."); | |
30ee7071 | 845 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_REFUSED, false); |
ceb17827 | 846 | return; |
b30bf55d LP |
847 | } |
848 | ||
849 | if (!DNS_PACKET_RD(p)) { | |
850 | /* If the "rd" bit is off (i.e. recursion was not requested), then refuse operation */ | |
851 | log_debug("Got request with recursion disabled, refusing."); | |
0354029b | 852 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_REFUSED, false); |
ceb17827 | 853 | return; |
b30bf55d LP |
854 | } |
855 | ||
bde69bbd LP |
856 | r = hashmap_ensure_allocated(queries_by_packet, &stub_packet_hash_ops); |
857 | if (r < 0) { | |
858 | log_oom(); | |
859 | return; | |
860 | } | |
861 | ||
b30bf55d | 862 | if (DNS_PACKET_DO(p) && DNS_PACKET_CD(p)) { |
775ae354 LP |
863 | log_debug("Got request with DNSSEC checking disabled, enabling bypass logic."); |
864 | ||
865 | r = dns_query_new(m, &q, NULL, NULL, p, 0, | |
866 | SD_RESOLVED_PROTOCOLS_ALL| | |
867 | SD_RESOLVED_NO_CNAME| | |
868 | SD_RESOLVED_NO_SEARCH| | |
869 | SD_RESOLVED_NO_VALIDATE| | |
870 | SD_RESOLVED_REQUIRE_PRIMARY| | |
871 | SD_RESOLVED_CLAMP_TTL); | |
872 | } else | |
873 | r = dns_query_new(m, &q, p->question, p->question, NULL, 0, | |
874 | SD_RESOLVED_PROTOCOLS_ALL| | |
875 | SD_RESOLVED_NO_SEARCH| | |
2f4d8e57 LP |
876 | SD_RESOLVED_NO_CNAME| |
877 | (DNS_PACKET_DO(p) ? SD_RESOLVED_REQUIRE_PRIMARY : 0)| | |
775ae354 | 878 | SD_RESOLVED_CLAMP_TTL); |
b30bf55d LP |
879 | if (r < 0) { |
880 | log_error_errno(r, "Failed to generate query object: %m"); | |
0354029b | 881 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_SERVFAIL, false); |
ceb17827 | 882 | return; |
b30bf55d LP |
883 | } |
884 | ||
775ae354 LP |
885 | q->request_packet = dns_packet_ref(p); |
886 | q->request_stream = dns_stream_ref(s); /* make sure the stream stays around until we can send a reply through it */ | |
0354029b | 887 | q->stub_listener_extra = l; |
b30bf55d LP |
888 | q->complete = dns_stub_query_complete; |
889 | ||
890 | if (s) { | |
b412af57 LP |
891 | /* Remember which queries belong to this stream, so that we can cancel them when the stream |
892 | * is disconnected early */ | |
893 | ||
ceb17827 | 894 | r = set_ensure_put(&s->queries, NULL, q); |
b412af57 LP |
895 | if (r < 0) { |
896 | log_oom(); | |
ceb17827 | 897 | return; |
b412af57 | 898 | } |
ceb17827 | 899 | assert(r > 0); |
b30bf55d LP |
900 | } |
901 | ||
bde69bbd LP |
902 | /* Add the query to the hash table we use to determine repeat packets now. We don't care about |
903 | * failures here, since in the worst case we'll not recognize duplicate incoming requests, which | |
904 | * isn't particularly bad. */ | |
905 | (void) hashmap_put(*queries_by_packet, q->request_packet, q); | |
906 | ||
b30bf55d LP |
907 | r = dns_query_go(q); |
908 | if (r < 0) { | |
909 | log_error_errno(r, "Failed to start query: %m"); | |
0354029b | 910 | dns_stub_send_failure(m, l, s, p, DNS_RCODE_SERVFAIL, false); |
ceb17827 | 911 | return; |
b30bf55d LP |
912 | } |
913 | ||
52e63427 | 914 | log_debug("Processing query..."); |
ceb17827 | 915 | TAKE_PTR(q); |
b30bf55d LP |
916 | } |
917 | ||
0354029b | 918 | static int on_dns_stub_packet_internal(sd_event_source *s, int fd, uint32_t revents, Manager *m, DnsStubListenerExtra *l) { |
b30bf55d | 919 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
b30bf55d LP |
920 | int r; |
921 | ||
922 | r = manager_recv(m, fd, DNS_PROTOCOL_DNS, &p); | |
923 | if (r <= 0) | |
924 | return r; | |
925 | ||
926 | if (dns_packet_validate_query(p) > 0) { | |
927 | log_debug("Got DNS stub UDP query packet for id %u", DNS_PACKET_ID(p)); | |
928 | ||
0354029b | 929 | dns_stub_process_query(m, l, NULL, p); |
b30bf55d LP |
930 | } else |
931 | log_debug("Invalid DNS stub UDP packet, ignoring."); | |
932 | ||
933 | return 0; | |
934 | } | |
935 | ||
d1fb8cda | 936 | static int on_dns_stub_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { |
0354029b | 937 | return on_dns_stub_packet_internal(s, fd, revents, userdata, NULL); |
d1fb8cda YW |
938 | } |
939 | ||
940 | static int on_dns_stub_packet_extra(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
0354029b LP |
941 | DnsStubListenerExtra *l = userdata; |
942 | ||
943 | assert(l); | |
944 | ||
945 | return on_dns_stub_packet_internal(s, fd, revents, l->manager, l); | |
d1fb8cda YW |
946 | } |
947 | ||
e4bed40f ZJS |
948 | static int on_dns_stub_stream_packet(DnsStream *s) { |
949 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
950 | ||
951 | assert(s); | |
952 | ||
953 | p = dns_stream_take_read_packet(s); | |
954 | assert(p); | |
955 | ||
956 | if (dns_packet_validate_query(p) > 0) { | |
957 | log_debug("Got DNS stub TCP query packet for id %u", DNS_PACKET_ID(p)); | |
958 | ||
959 | dns_stub_process_query(s->manager, s->stub_listener_extra, s, p); | |
960 | } else | |
961 | log_debug("Invalid DNS stub TCP packet, ignoring."); | |
962 | ||
963 | return 0; | |
964 | } | |
965 | ||
966 | static int on_dns_stub_stream_internal(sd_event_source *s, int fd, uint32_t revents, Manager *m, DnsStubListenerExtra *l) { | |
967 | DnsStream *stream; | |
968 | int cfd, r; | |
969 | ||
970 | cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC); | |
971 | if (cfd < 0) { | |
972 | if (ERRNO_IS_ACCEPT_AGAIN(errno)) | |
973 | return 0; | |
974 | ||
975 | return -errno; | |
976 | } | |
977 | ||
978 | r = dns_stream_new(m, &stream, DNS_STREAM_STUB, DNS_PROTOCOL_DNS, cfd, NULL); | |
979 | if (r < 0) { | |
980 | safe_close(cfd); | |
981 | return r; | |
982 | } | |
983 | ||
984 | stream->stub_listener_extra = l; | |
985 | stream->on_packet = on_dns_stub_stream_packet; | |
986 | stream->complete = dns_stub_stream_complete; | |
987 | ||
988 | /* We let the reference to the stream dangle here, it will be dropped later by the complete callback. */ | |
989 | ||
990 | return 0; | |
991 | } | |
992 | ||
993 | static int on_dns_stub_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
994 | return on_dns_stub_stream_internal(s, fd, revents, userdata, NULL); | |
995 | } | |
996 | ||
997 | static int on_dns_stub_stream_extra(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
998 | DnsStubListenerExtra *l = userdata; | |
999 | ||
1000 | assert(l); | |
1001 | return on_dns_stub_stream_internal(s, fd, revents, l->manager, l); | |
1002 | } | |
1003 | ||
af8b1384 | 1004 | static int set_dns_stub_common_socket_options(int fd, int family) { |
1f05101f SS |
1005 | int r; |
1006 | ||
1007 | assert(fd >= 0); | |
af8b1384 | 1008 | assert(IN_SET(family, AF_INET, AF_INET6)); |
1f05101f SS |
1009 | |
1010 | r = setsockopt_int(fd, SOL_SOCKET, SO_REUSEADDR, true); | |
1011 | if (r < 0) | |
1012 | return r; | |
1013 | ||
5d0fe423 LP |
1014 | r = socket_set_recvpktinfo(fd, family, true); |
1015 | if (r < 0) | |
1016 | return r; | |
af8b1384 | 1017 | |
5d0fe423 LP |
1018 | r = socket_set_recvttl(fd, family, true); |
1019 | if (r < 0) | |
1020 | return r; | |
af8b1384 YW |
1021 | |
1022 | return 0; | |
1f05101f SS |
1023 | } |
1024 | ||
8624f128 LP |
1025 | static int set_dns_stub_common_tcp_socket_options(int fd) { |
1026 | int r; | |
1027 | ||
1028 | assert(fd >= 0); | |
1029 | ||
1030 | r = setsockopt_int(fd, IPPROTO_TCP, TCP_FASTOPEN, 5); /* Everybody appears to pick qlen=5, let's do the same here. */ | |
1031 | if (r < 0) | |
1032 | log_debug_errno(r, "Failed to enable TCP_FASTOPEN on TCP listening socket, ignoring: %m"); | |
1033 | ||
1034 | r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true); | |
1035 | if (r < 0) | |
1036 | log_debug_errno(r, "Failed to enable TCP_NODELAY mode, ignoring: %m"); | |
1037 | ||
1038 | return 0; | |
1039 | } | |
1040 | ||
d491917c | 1041 | static int manager_dns_stub_fd(Manager *m, int type) { |
b30bf55d LP |
1042 | union sockaddr_union sa = { |
1043 | .in.sin_family = AF_INET, | |
b30bf55d | 1044 | .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB), |
d491917c | 1045 | .in.sin_port = htobe16(53), |
b30bf55d | 1046 | }; |
424e490b | 1047 | _cleanup_close_ int fd = -1; |
b30bf55d LP |
1048 | int r; |
1049 | ||
d491917c ZJS |
1050 | assert(IN_SET(type, SOCK_DGRAM, SOCK_STREAM)); |
1051 | ||
1052 | sd_event_source **event_source = type == SOCK_DGRAM ? &m->dns_stub_udp_event_source : &m->dns_stub_tcp_event_source; | |
1053 | if (*event_source) | |
1054 | return sd_event_source_get_io_fd(*event_source); | |
b30bf55d | 1055 | |
d491917c | 1056 | fd = socket(AF_INET, type | SOCK_CLOEXEC | SOCK_NONBLOCK, 0); |
424e490b | 1057 | if (fd < 0) |
b30bf55d LP |
1058 | return -errno; |
1059 | ||
af8b1384 | 1060 | r = set_dns_stub_common_socket_options(fd, AF_INET); |
2ff48e98 LP |
1061 | if (r < 0) |
1062 | return r; | |
b30bf55d | 1063 | |
8624f128 LP |
1064 | if (type == SOCK_STREAM) { |
1065 | r = set_dns_stub_common_tcp_socket_options(fd); | |
1066 | if (r < 0) | |
1067 | return r; | |
1068 | } | |
1069 | ||
b30bf55d | 1070 | /* Make sure no traffic from outside the local host can leak to onto this socket */ |
953a02d1 LP |
1071 | r = socket_bind_to_ifindex(fd, LOOPBACK_IFINDEX); |
1072 | if (r < 0) | |
1073 | return r; | |
b30bf55d | 1074 | |
d491917c ZJS |
1075 | r = setsockopt_int(fd, IPPROTO_IP, IP_TTL, 1); |
1076 | if (r < 0) | |
1077 | return r; | |
1078 | ||
424e490b ZJS |
1079 | if (bind(fd, &sa.sa, sizeof(sa.in)) < 0) |
1080 | return -errno; | |
b30bf55d | 1081 | |
d491917c ZJS |
1082 | if (type == SOCK_STREAM && |
1083 | listen(fd, SOMAXCONN) < 0) | |
1084 | return -errno; | |
1085 | ||
1086 | r = sd_event_add_io(m->event, event_source, fd, EPOLLIN, | |
1087 | type == SOCK_DGRAM ? on_dns_stub_packet : on_dns_stub_stream, | |
1088 | m); | |
b30bf55d | 1089 | if (r < 0) |
424e490b | 1090 | return r; |
b30bf55d | 1091 | |
d491917c | 1092 | r = sd_event_source_set_io_fd_own(*event_source, true); |
7216a3b5 YW |
1093 | if (r < 0) |
1094 | return r; | |
1095 | ||
d491917c ZJS |
1096 | (void) sd_event_source_set_description(*event_source, |
1097 | type == SOCK_DGRAM ? "dns-stub-udp" : "dns-stub-tcp"); | |
b30bf55d | 1098 | |
7216a3b5 | 1099 | return TAKE_FD(fd); |
b30bf55d LP |
1100 | } |
1101 | ||
b5febb3f | 1102 | static int manager_dns_stub_fd_extra(Manager *m, DnsStubListenerExtra *l, int type) { |
1f05101f SS |
1103 | _cleanup_free_ char *pretty = NULL; |
1104 | _cleanup_close_ int fd = -1; | |
ca8b62b5 | 1105 | union sockaddr_union sa; |
1f05101f SS |
1106 | int r; |
1107 | ||
0354029b | 1108 | assert(m); |
b5febb3f | 1109 | assert(IN_SET(type, SOCK_DGRAM, SOCK_STREAM)); |
0354029b | 1110 | |
d491917c ZJS |
1111 | if (!l) |
1112 | return manager_dns_stub_fd(m, type); | |
0354029b | 1113 | |
b5febb3f ZJS |
1114 | sd_event_source **event_source = type == SOCK_DGRAM ? &l->udp_event_source : &l->tcp_event_source; |
1115 | if (*event_source) | |
1116 | return sd_event_source_get_io_fd(*event_source); | |
1f05101f | 1117 | |
ca8b62b5 YW |
1118 | if (l->family == AF_INET) |
1119 | sa = (union sockaddr_union) { | |
1120 | .in.sin_family = l->family, | |
49ef064c | 1121 | .in.sin_port = htobe16(dns_stub_listener_extra_port(l)), |
ca8b62b5 YW |
1122 | .in.sin_addr = l->address.in, |
1123 | }; | |
1124 | else | |
1125 | sa = (union sockaddr_union) { | |
1126 | .in6.sin6_family = l->family, | |
49ef064c | 1127 | .in6.sin6_port = htobe16(dns_stub_listener_extra_port(l)), |
ca8b62b5 YW |
1128 | .in6.sin6_addr = l->address.in6, |
1129 | }; | |
1130 | ||
b5febb3f | 1131 | fd = socket(l->family, type | SOCK_CLOEXEC | SOCK_NONBLOCK, 0); |
1f05101f SS |
1132 | if (fd < 0) { |
1133 | r = -errno; | |
1134 | goto fail; | |
1135 | } | |
1136 | ||
af8b1384 | 1137 | r = set_dns_stub_common_socket_options(fd, l->family); |
1f05101f SS |
1138 | if (r < 0) |
1139 | goto fail; | |
1140 | ||
8624f128 LP |
1141 | if (type == SOCK_STREAM) { |
1142 | r = set_dns_stub_common_tcp_socket_options(fd); | |
1143 | if (r < 0) | |
1144 | goto fail; | |
1145 | } | |
1146 | ||
69e3234d | 1147 | /* Do not set IP_TTL for extra DNS stub listeners, as the address may not be local and in that case |
b5febb3f ZJS |
1148 | * people may want ttl > 1. */ |
1149 | ||
5d0fe423 | 1150 | r = socket_set_freebind(fd, l->family, true); |
b5febb3f ZJS |
1151 | if (r < 0) |
1152 | goto fail; | |
1153 | ||
eb170e75 LP |
1154 | if (type == SOCK_DGRAM) { |
1155 | r = socket_disable_pmtud(fd, l->family); | |
1156 | if (r < 0) | |
1157 | log_debug_errno(r, "Failed to disable UDP PMTUD, ignoring: %m"); | |
20a001bd LP |
1158 | |
1159 | r = socket_set_recvfragsize(fd, l->family, true); | |
1160 | if (r < 0) | |
1161 | log_debug_errno(r, "Failed to enable fragment size reception, ignoring: %m"); | |
eb170e75 LP |
1162 | } |
1163 | ||
ca8b62b5 | 1164 | if (bind(fd, &sa.sa, SOCKADDR_LEN(sa)) < 0) { |
1f05101f SS |
1165 | r = -errno; |
1166 | goto fail; | |
1167 | } | |
1168 | ||
b5febb3f ZJS |
1169 | if (type == SOCK_STREAM && |
1170 | listen(fd, SOMAXCONN) < 0) { | |
1171 | r = -errno; | |
1172 | goto fail; | |
1173 | } | |
1174 | ||
1175 | r = sd_event_add_io(m->event, event_source, fd, EPOLLIN, | |
1176 | type == SOCK_DGRAM ? on_dns_stub_packet_extra : on_dns_stub_stream_extra, | |
1177 | l); | |
1f05101f SS |
1178 | if (r < 0) |
1179 | goto fail; | |
1180 | ||
b5febb3f | 1181 | r = sd_event_source_set_io_fd_own(*event_source, true); |
7216a3b5 YW |
1182 | if (r < 0) |
1183 | goto fail; | |
1184 | ||
b5febb3f ZJS |
1185 | (void) sd_event_source_set_description(*event_source, |
1186 | type == SOCK_DGRAM ? "dns-stub-udp-extra" : "dns-stub-tcp-extra"); | |
1f05101f SS |
1187 | |
1188 | if (DEBUG_LOGGING) { | |
ca8b62b5 | 1189 | (void) in_addr_port_to_string(l->family, &l->address, l->port, &pretty); |
b5febb3f ZJS |
1190 | log_debug("Listening on %s socket %s.", |
1191 | type == SOCK_DGRAM ? "UDP" : "TCP", | |
1192 | strnull(pretty)); | |
1f05101f SS |
1193 | } |
1194 | ||
7216a3b5 | 1195 | return TAKE_FD(fd); |
1f05101f | 1196 | |
b4b7ea1b | 1197 | fail: |
1c17bcb3 | 1198 | assert(r < 0); |
ca8b62b5 | 1199 | (void) in_addr_port_to_string(l->family, &l->address, l->port, &pretty); |
b5febb3f ZJS |
1200 | return log_warning_errno(r, |
1201 | r == -EADDRINUSE ? "Another process is already listening on %s socket %s: %m" : | |
1202 | "Failed to listen on %s socket %s: %m", | |
1203 | type == SOCK_DGRAM ? "UDP" : "TCP", | |
1204 | strnull(pretty)); | |
1f05101f SS |
1205 | } |
1206 | ||
b30bf55d | 1207 | int manager_dns_stub_start(Manager *m) { |
424e490b | 1208 | const char *t = "UDP"; |
01b0669e | 1209 | int r = 0; |
b30bf55d LP |
1210 | |
1211 | assert(m); | |
1212 | ||
d5da7707 ZJS |
1213 | if (m->dns_stub_listener_mode == DNS_STUB_LISTENER_NO) |
1214 | log_debug("Not creating stub listener."); | |
1215 | else | |
1216 | log_debug("Creating stub listener using %s.", | |
1217 | m->dns_stub_listener_mode == DNS_STUB_LISTENER_UDP ? "UDP" : | |
1218 | m->dns_stub_listener_mode == DNS_STUB_LISTENER_TCP ? "TCP" : | |
1219 | "UDP/TCP"); | |
1220 | ||
88d2cb7c | 1221 | if (FLAGS_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_UDP)) |
d491917c | 1222 | r = manager_dns_stub_fd(m, SOCK_DGRAM); |
b30bf55d | 1223 | |
424e490b | 1224 | if (r >= 0 && |
88d2cb7c | 1225 | FLAGS_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_TCP)) { |
424e490b | 1226 | t = "TCP"; |
d491917c | 1227 | r = manager_dns_stub_fd(m, SOCK_STREAM); |
1ae43295 | 1228 | } |
b30bf55d | 1229 | |
0f4db364 | 1230 | if (IN_SET(r, -EADDRINUSE, -EPERM)) { |
d491917c ZJS |
1231 | log_warning_errno(r, |
1232 | r == -EADDRINUSE ? "Another process is already listening on %s socket 127.0.0.53:53.\n" | |
1233 | "Turning off local DNS stub support." : | |
1234 | "Failed to listen on %s socket 127.0.0.53:53: %m.\n" | |
1235 | "Turning off local DNS stub support.", | |
1236 | t); | |
424e490b ZJS |
1237 | manager_dns_stub_stop(m); |
1238 | } else if (r < 0) | |
1239 | return log_error_errno(r, "Failed to listen on %s socket 127.0.0.53:53: %m", t); | |
b30bf55d | 1240 | |
1f05101f | 1241 | if (!ordered_set_isempty(m->dns_extra_stub_listeners)) { |
36aaabc3 | 1242 | DnsStubListenerExtra *l; |
1f05101f | 1243 | |
dce65cd4 | 1244 | log_debug("Creating extra stub listeners."); |
1f05101f | 1245 | |
90e74a66 | 1246 | ORDERED_SET_FOREACH(l, m->dns_extra_stub_listeners) { |
7314b397 | 1247 | if (FLAGS_SET(l->mode, DNS_STUB_LISTENER_UDP)) |
b5febb3f | 1248 | (void) manager_dns_stub_fd_extra(m, l, SOCK_DGRAM); |
7314b397 | 1249 | if (FLAGS_SET(l->mode, DNS_STUB_LISTENER_TCP)) |
b5febb3f | 1250 | (void) manager_dns_stub_fd_extra(m, l, SOCK_STREAM); |
7314b397 | 1251 | } |
1f05101f SS |
1252 | } |
1253 | ||
b30bf55d LP |
1254 | return 0; |
1255 | } | |
1256 | ||
1257 | void manager_dns_stub_stop(Manager *m) { | |
1258 | assert(m); | |
1259 | ||
1260 | m->dns_stub_udp_event_source = sd_event_source_unref(m->dns_stub_udp_event_source); | |
1261 | m->dns_stub_tcp_event_source = sd_event_source_unref(m->dns_stub_tcp_event_source); | |
b30bf55d | 1262 | } |
ae8f0ec3 LP |
1263 | |
1264 | static const char* const dns_stub_listener_mode_table[_DNS_STUB_LISTENER_MODE_MAX] = { | |
1265 | [DNS_STUB_LISTENER_NO] = "no", | |
1266 | [DNS_STUB_LISTENER_UDP] = "udp", | |
1267 | [DNS_STUB_LISTENER_TCP] = "tcp", | |
1268 | [DNS_STUB_LISTENER_YES] = "yes", | |
1269 | }; | |
1270 | DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(dns_stub_listener_mode, DnsStubListenerMode, DNS_STUB_LISTENER_YES); |