src/resolve/resolved-dns-stream.c

   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         /* Disconnect us from the server object if we are now not usable anymore */
  22         dns_stream_detach(s);
  23 }
  24
  25 static int dns_stream_update_io(DnsStream *s) {
  26         int f = 0;
  27
  28         assert(s);
  29
  30         if (s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size)
  31                 f |= EPOLLOUT;
  32         else if (!ordered_set_isempty(s->write_queue)) {
  33                 dns_packet_unref(s->write_packet);
  34                 s->write_packet = ordered_set_steal_first(s->write_queue);
  35                 s->write_size = htobe16(s->write_packet->size);
  36                 s->n_written = 0;
  37                 f |= EPOLLOUT;
  38         }
  39         if (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size)
  40                 f |= EPOLLIN;
  41
  42 #if ENABLE_DNS_OVER_TLS
  43         /* For handshake and clean closing purposes, TLS can override requested events */
  44         if (s->dnstls_events != 0)
  45                 f = s->dnstls_events;
  46 #endif
  47
  48         return sd_event_source_set_io_events(s->io_event_source, f);
  49 }
  50
  51 static int dns_stream_complete(DnsStream *s, int error) {
  52         _cleanup_(dns_stream_unrefp) _unused_ DnsStream *ref = dns_stream_ref(s); /* Protect stream while we process it */
  53
  54         assert(s);
  55         assert(error >= 0);
  56
  57         /* Error is > 0 when the connection failed for some reason in the network stack. It's == 0 if we sent
  58          * and receieved exactly one packet each (in the LLMNR client case). */
  59
  60 #if ENABLE_DNS_OVER_TLS
  61         if (s->encrypted) {
  62                 int r;
  63
  64                 r = dnstls_stream_shutdown(s, error);
  65                 if (r != -EAGAIN)
  66                         dns_stream_stop(s);
  67         } else
  68 #endif
  69                 dns_stream_stop(s);
  70
  71         dns_stream_detach(s);
  72
  73         if (s->complete)
  74                 s->complete(s, error);
  75         else /* the default action if no completion function is set is to close the stream */
  76                 dns_stream_unref(s);
  77
  78         return 0;
  79 }
  80
  81 static int dns_stream_identify(DnsStream *s) {
  82         union {
  83                 struct cmsghdr header; /* For alignment */
  84                 uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
  85                                + EXTRA_CMSG_SPACE /* kernel appears to require extra space */];
  86         } control;
  87         struct msghdr mh = {};
  88         struct cmsghdr *cmsg;
  89         socklen_t sl;
  90         int r;
  91
  92         assert(s);
  93
  94         if (s->identified)
  95                 return 0;
  96
  97         /* Query the local side */
  98         s->local_salen = sizeof(s->local);
  99         r = getsockname(s->fd, &s->local.sa, &s->local_salen);
 100         if (r < 0)
 101                 return -errno;
 102         if (s->local.sa.sa_family == AF_INET6 && s->ifindex <= 0)
 103                 s->ifindex = s->local.in6.sin6_scope_id;
 104
 105         /* Query the remote side */
 106         s->peer_salen = sizeof(s->peer);
 107         r = getpeername(s->fd, &s->peer.sa, &s->peer_salen);
 108         if (r < 0)
 109                 return -errno;
 110         if (s->peer.sa.sa_family == AF_INET6 && s->ifindex <= 0)
 111                 s->ifindex = s->peer.in6.sin6_scope_id;
 112
 113         /* Check consistency */
 114         assert(s->peer.sa.sa_family == s->local.sa.sa_family);
 115         assert(IN_SET(s->peer.sa.sa_family, AF_INET, AF_INET6));
 116
 117         /* Query connection meta information */
 118         sl = sizeof(control);
 119         if (s->peer.sa.sa_family == AF_INET) {
 120                 r = getsockopt(s->fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl);
 121                 if (r < 0)
 122                         return -errno;
 123         } else if (s->peer.sa.sa_family == AF_INET6) {
 124
 125                 r = getsockopt(s->fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl);
 126                 if (r < 0)
 127                         return -errno;
 128         } else
 129                 return -EAFNOSUPPORT;
 130
 131         mh.msg_control = &control;
 132         mh.msg_controllen = sl;
 133
 134         CMSG_FOREACH(cmsg, &mh) {
 135
 136                 if (cmsg->cmsg_level == IPPROTO_IPV6) {
 137                         assert(s->peer.sa.sa_family == AF_INET6);
 138
 139                         switch (cmsg->cmsg_type) {
 140
 141                         case IPV6_PKTINFO: {
 142                                 struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);
 143
 144                                 if (s->ifindex <= 0)
 145                                         s->ifindex = i->ipi6_ifindex;
 146                                 break;
 147                         }
 148
 149                         case IPV6_HOPLIMIT:
 150                                 s->ttl = *(int *) CMSG_DATA(cmsg);
 151                                 break;
 152                         }
 153
 154                 } else if (cmsg->cmsg_level == IPPROTO_IP) {
 155                         assert(s->peer.sa.sa_family == AF_INET);
 156
 157                         switch (cmsg->cmsg_type) {
 158
 159                         case IP_PKTINFO: {
 160                                 struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);
 161
 162                                 if (s->ifindex <= 0)
 163                                         s->ifindex = i->ipi_ifindex;
 164                                 break;
 165                         }
 166
 167                         case IP_TTL:
 168                                 s->ttl = *(int *) CMSG_DATA(cmsg);
 169                                 break;
 170                         }
 171                 }
 172         }
 173
 174         /* The Linux kernel sets the interface index to the loopback
 175          * device if the connection came from the local host since it
 176          * avoids the routing table in such a case. Let's unset the
 177          * interface index in such a case. */
 178         if (s->ifindex == LOOPBACK_IFINDEX)
 179                 s->ifindex = 0;
 180
 181         /* If we don't know the interface index still, we look for the
 182          * first local interface with a matching address. Yuck! */
 183         if (s->ifindex <= 0)
 184                 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);
 185
 186         if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) {
 187                 uint32_t ifindex = htobe32(s->ifindex);
 188
 189                 /* Make sure all packets for this connection are sent on the same interface */
 190                 if (s->local.sa.sa_family == AF_INET) {
 191                         r = setsockopt(s->fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex));
 192                         if (r < 0)
 193                                 log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF: %m");
 194                 } else if (s->local.sa.sa_family == AF_INET6) {
 195                         r = setsockopt(s->fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex));
 196                         if (r < 0)
 197                                 log_debug_errno(errno, "Failed to invoke IPV6_UNICAST_IF: %m");
 198                 }
 199         }
 200
 201         s->identified = true;
 202
 203         return 0;
 204 }
 205
 206 ssize_t dns_stream_writev(DnsStream *s, const struct iovec *iov, size_t iovcnt, int flags) {
 207         ssize_t m;
 208
 209         assert(s);
 210         assert(iov);
 211
 212 #if ENABLE_DNS_OVER_TLS
 213         if (s->encrypted && !(flags & DNS_STREAM_WRITE_TLS_DATA)) {
 214                 ssize_t ss;
 215                 size_t i;
 216
 217                 m = 0;
 218                 for (i = 0; i < iovcnt; i++) {
 219                         ss = dnstls_stream_write(s, iov[i].iov_base, iov[i].iov_len);
 220                         if (ss < 0)
 221                                 return ss;
 222
 223                         m += ss;
 224                         if (ss != (ssize_t) iov[i].iov_len)
 225                                 continue;
 226                 }
 227         } else
 228 #endif
 229         if (s->tfo_salen > 0) {
 230                 struct msghdr hdr = {
 231                         .msg_iov = (struct iovec*) iov,
 232                         .msg_iovlen = iovcnt,
 233                         .msg_name = &s->tfo_address.sa,
 234                         .msg_namelen = s->tfo_salen
 235                 };
 236
 237                 m = sendmsg(s->fd, &hdr, MSG_FASTOPEN);
 238                 if (m < 0) {
 239                         if (errno == EOPNOTSUPP) {
 240                                 s->tfo_salen = 0;
 241                                 if (connect(s->fd, &s->tfo_address.sa, s->tfo_salen) < 0)
 242                                         return -errno;
 243
 244                                 return -EAGAIN;
 245                         }
 246                         if (errno == EINPROGRESS)
 247                                 return -EAGAIN;
 248
 249                         return -errno;
 250                 } else
 251                         s->tfo_salen = 0; /* connection is made */
 252         } else {
 253                 m = writev(s->fd, iov, iovcnt);
 254                 if (m < 0)
 255                         return -errno;
 256         }
 257
 258         return m;
 259 }
 260
 261 static ssize_t dns_stream_read(DnsStream *s, void *buf, size_t count) {
 262         ssize_t ss;
 263
 264 #if ENABLE_DNS_OVER_TLS
 265         if (s->encrypted)
 266                 ss = dnstls_stream_read(s, buf, count);
 267         else
 268 #endif
 269         {
 270                 ss = read(s->fd, buf, count);
 271                 if (ss < 0)
 272                         return -errno;
 273         }
 274
 275         return ss;
 276 }
 277
 278 static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) {
 279         DnsStream *s = userdata;
 280
 281         assert(s);
 282
 283         return dns_stream_complete(s, ETIMEDOUT);
 284 }
 285
 286 static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
 287         _cleanup_(dns_stream_unrefp) DnsStream *s = dns_stream_ref(userdata); /* Protect stream while we process it */
 288         bool progressed = false;
 289         int r;
 290
 291         assert(s);
 292
 293 #if ENABLE_DNS_OVER_TLS
 294         if (s->encrypted) {
 295                 r = dnstls_stream_on_io(s, revents);
 296                 if (r == DNSTLS_STREAM_CLOSED)
 297                         return 0;
 298                 if (r == -EAGAIN)
 299                         return dns_stream_update_io(s);
 300                 if (r < 0)
 301                         return dns_stream_complete(s, -r);
 302
 303                 r = dns_stream_update_io(s);
 304                 if (r < 0)
 305                         return r;
 306         }
 307 #endif
 308
 309         /* only identify after connecting */
 310         if (s->tfo_salen == 0) {
 311                 r = dns_stream_identify(s);
 312                 if (r < 0)
 313                         return dns_stream_complete(s, -r);
 314         }
 315
 316         if ((revents & EPOLLOUT) &&
 317             s->write_packet &&
 318             s->n_written < sizeof(s->write_size) + s->write_packet->size) {
 319
 320                 struct iovec iov[2];
 321                 ssize_t ss;
 322
 323                 iov[0] = IOVEC_MAKE(&s->write_size, sizeof(s->write_size));
 324                 iov[1] = IOVEC_MAKE(DNS_PACKET_DATA(s->write_packet), s->write_packet->size);
 325
 326                 IOVEC_INCREMENT(iov, 2, s->n_written);
 327
 328                 ss = dns_stream_writev(s, iov, 2, 0);
 329                 if (ss < 0) {
 330                         if (!IN_SET(-ss, EINTR, EAGAIN))
 331                                 return dns_stream_complete(s, -ss);
 332                 } else {
 333                         progressed = true;
 334                         s->n_written += ss;
 335                 }
 336
 337                 /* Are we done? If so, disable the event source for EPOLLOUT */
 338                 if (s->n_written >= sizeof(s->write_size) + s->write_packet->size) {
 339                         r = dns_stream_update_io(s);
 340                         if (r < 0)
 341                                 return dns_stream_complete(s, -r);
 342                 }
 343         }
 344
 345         if ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) &&
 346             (!s->read_packet ||
 347              s->n_read < sizeof(s->read_size) + s->read_packet->size)) {
 348
 349                 if (s->n_read < sizeof(s->read_size)) {
 350                         ssize_t ss;
 351
 352                         ss = dns_stream_read(s, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read);
 353                         if (ss < 0) {
 354                                 if (!IN_SET(-ss, EINTR, EAGAIN))
 355                                         return dns_stream_complete(s, -ss);
 356                         } else if (ss == 0)
 357                                 return dns_stream_complete(s, ECONNRESET);
 358                         else {
 359                                 progressed = true;
 360                                 s->n_read += ss;
 361                         }
 362                 }
 363
 364                 if (s->n_read >= sizeof(s->read_size)) {
 365
 366                         if (be16toh(s->read_size) < DNS_PACKET_HEADER_SIZE)
 367                                 return dns_stream_complete(s, EBADMSG);
 368
 369                         if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) {
 370                                 ssize_t ss;
 371
 372                                 if (!s->read_packet) {
 373                                         r = dns_packet_new(&s->read_packet, s->protocol, be16toh(s->read_size), DNS_PACKET_SIZE_MAX);
 374                                         if (r < 0)
 375                                                 return dns_stream_complete(s, -r);
 376
 377                                         s->read_packet->size = be16toh(s->read_size);
 378                                         s->read_packet->ipproto = IPPROTO_TCP;
 379                                         s->read_packet->family = s->peer.sa.sa_family;
 380                                         s->read_packet->ttl = s->ttl;
 381                                         s->read_packet->ifindex = s->ifindex;
 382
 383                                         if (s->read_packet->family == AF_INET) {
 384                                                 s->read_packet->sender.in = s->peer.in.sin_addr;
 385                                                 s->read_packet->sender_port = be16toh(s->peer.in.sin_port);
 386                                                 s->read_packet->destination.in = s->local.in.sin_addr;
 387                                                 s->read_packet->destination_port = be16toh(s->local.in.sin_port);
 388                                         } else {
 389                                                 assert(s->read_packet->family == AF_INET6);
 390                                                 s->read_packet->sender.in6 = s->peer.in6.sin6_addr;
 391                                                 s->read_packet->sender_port = be16toh(s->peer.in6.sin6_port);
 392                                                 s->read_packet->destination.in6 = s->local.in6.sin6_addr;
 393                                                 s->read_packet->destination_port = be16toh(s->local.in6.sin6_port);
 394
 395                                                 if (s->read_packet->ifindex == 0)
 396                                                         s->read_packet->ifindex = s->peer.in6.sin6_scope_id;
 397                                                 if (s->read_packet->ifindex == 0)
 398                                                         s->read_packet->ifindex = s->local.in6.sin6_scope_id;
 399                                         }
 400                                 }
 401
 402                                 ss = dns_stream_read(s,
 403                                           (uint8_t*) DNS_PACKET_DATA(s->read_packet) + s->n_read - sizeof(s->read_size),
 404                                           sizeof(s->read_size) + be16toh(s->read_size) - s->n_read);
 405                                 if (ss < 0) {
 406                                         if (!IN_SET(-ss, EINTR, EAGAIN))
 407                                                 return dns_stream_complete(s, -ss);
 408                                 } else if (ss == 0)
 409                                         return dns_stream_complete(s, ECONNRESET);
 410                                 else
 411                                         s->n_read += ss;
 412                         }
 413
 414                         /* Are we done? If so, disable the event source for EPOLLIN */
 415                         if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) {
 416                                 /* If there's a packet handler
 417                                  * installed, call that. Note that
 418                                  * this is optional... */
 419                                 if (s->on_packet) {
 420                                         r = s->on_packet(s);
 421                                         if (r < 0)
 422                                                 return r;
 423                                 }
 424
 425                                 r = dns_stream_update_io(s);
 426                                 if (r < 0)
 427                                         return dns_stream_complete(s, -r);
 428                         }
 429                 }
 430         }
 431
 432         /* Call "complete" callback if finished reading and writing one packet, and there's nothing else left
 433          * to write. */
 434         if (s->type == DNS_STREAM_LLMNR_SEND &&
 435             (s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) &&
 436             ordered_set_isempty(s->write_queue) &&
 437             (s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size))
 438                 return dns_stream_complete(s, 0);
 439
 440         /* If we did something, let's restart the timeout event source */
 441         if (progressed && s->timeout_event_source) {
 442                 r = sd_event_source_set_time(s->timeout_event_source, now(clock_boottime_or_monotonic()) + DNS_STREAM_TIMEOUT_USEC);
 443                 if (r < 0)
 444                         log_warning_errno(errno, "Couldn't restart TCP connection timeout, ignoring: %m");
 445         }
 446
 447         return 0;
 448 }
 449
 450 static DnsStream *dns_stream_free(DnsStream *s) {
 451         DnsPacket *p;
 452         Iterator i;
 453
 454         assert(s);
 455
 456         dns_stream_stop(s);
 457
 458         if (s->manager) {
 459                 LIST_REMOVE(streams, s->manager->dns_streams, s);
 460                 s->manager->n_dns_streams[s->type]--;
 461         }
 462
 463 #if ENABLE_DNS_OVER_TLS
 464         if (s->encrypted)
 465                 dnstls_stream_free(s);
 466 #endif
 467
 468         ORDERED_SET_FOREACH(p, s->write_queue, i)
 469                 dns_packet_unref(ordered_set_remove(s->write_queue, p));
 470
 471         dns_packet_unref(s->write_packet);
 472         dns_packet_unref(s->read_packet);
 473         dns_server_unref(s->server);
 474
 475         ordered_set_free(s->write_queue);
 476
 477         return mfree(s);
 478 }
 479
 480 DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsStream, dns_stream, dns_stream_free);
 481
 482 int dns_stream_new(
 483                 Manager *m,
 484                 DnsStream **ret,
 485                 DnsStreamType type,
 486                 DnsProtocol protocol,
 487                 int fd,
 488                 const union sockaddr_union *tfo_address) {
 489
 490         _cleanup_(dns_stream_unrefp) DnsStream *s = NULL;
 491         int r;
 492
 493         assert(m);
 494         assert(ret);
 495         assert(type >= 0);
 496         assert(type < _DNS_STREAM_TYPE_MAX);
 497         assert(protocol >= 0);
 498         assert(protocol < _DNS_PROTOCOL_MAX);
 499         assert(fd >= 0);
 500
 501         if (m->n_dns_streams[type] > DNS_STREAMS_MAX)
 502                 return -EBUSY;
 503
 504         s = new(DnsStream, 1);
 505         if (!s)
 506                 return -ENOMEM;
 507
 508         *s = (DnsStream) {
 509                 .n_ref = 1,
 510                 .fd = -1,
 511                 .protocol = protocol,
 512         };
 513
 514         r = ordered_set_ensure_allocated(&s->write_queue, &dns_packet_hash_ops);
 515         if (r < 0)
 516                 return r;
 517
 518         r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s);
 519         if (r < 0)
 520                 return r;
 521
 522         (void) sd_event_source_set_description(s->io_event_source, "dns-stream-io");
 523
 524         r = sd_event_add_time(
 525                         m->event,
 526                         &s->timeout_event_source,
 527                         clock_boottime_or_monotonic(),
 528                         now(clock_boottime_or_monotonic()) + DNS_STREAM_TIMEOUT_USEC, 0,
 529                         on_stream_timeout, s);
 530         if (r < 0)
 531                 return r;
 532
 533         (void) sd_event_source_set_description(s->timeout_event_source, "dns-stream-timeout");
 534
 535         LIST_PREPEND(streams, m->dns_streams, s);
 536         m->n_dns_streams[type]++;
 537         s->manager = m;
 538
 539         s->fd = fd;
 540
 541         if (tfo_address) {
 542                 s->tfo_address = *tfo_address;
 543                 s->tfo_salen = tfo_address->sa.sa_family == AF_INET6 ? sizeof(tfo_address->in6) : sizeof(tfo_address->in);
 544         }
 545
 546         *ret = TAKE_PTR(s);
 547
 548         return 0;
 549 }
 550
 551 int dns_stream_write_packet(DnsStream *s, DnsPacket *p) {
 552         int r;
 553
 554         assert(s);
 555         assert(p);
 556
 557         r = ordered_set_put(s->write_queue, p);
 558         if (r < 0)
 559                 return r;
 560
 561         dns_packet_ref(p);
 562
 563         return dns_stream_update_io(s);
 564 }
 565
 566 DnsPacket *dns_stream_take_read_packet(DnsStream *s) {
 567         assert(s);
 568
 569         if (!s->read_packet)
 570                 return NULL;
 571
 572         if (s->n_read < sizeof(s->read_size))
 573                 return NULL;
 574
 575         if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size))
 576                 return NULL;
 577
 578         s->n_read = 0;
 579         return TAKE_PTR(s->read_packet);
 580 }
 581
 582 void dns_stream_detach(DnsStream *s) {
 583         assert(s);
 584
 585         if (!s->server)
 586                 return;
 587
 588         if (s->server->stream != s)
 589                 return;
 590
 591         dns_server_unref_stream(s->server);
 592 }