/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include "alloc-util.h" #include "fd-util.h" #include "io-util.h" #include "missing_network.h" #include "resolved-dns-stream.h" #include "resolved-manager.h" #define DNS_STREAM_TIMEOUT_USEC (10 * USEC_PER_SEC) #define DNS_STREAMS_MAX 128 #define DNS_QUERIES_PER_STREAM 32 static void dns_stream_stop(DnsStream *s) { assert(s); s->io_event_source = sd_event_source_unref(s->io_event_source); s->timeout_event_source = sd_event_source_unref(s->timeout_event_source); s->fd = safe_close(s->fd); /* Disconnect us from the server object if we are now not usable anymore */ dns_stream_detach(s); } static int dns_stream_update_io(DnsStream *s) { int f = 0; assert(s); if (s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size) f |= EPOLLOUT; else if (!ordered_set_isempty(s->write_queue)) { dns_packet_unref(s->write_packet); s->write_packet = ordered_set_steal_first(s->write_queue); s->write_size = htobe16(s->write_packet->size); s->n_written = 0; f |= EPOLLOUT; } /* Let's read a packet if we haven't queued any yet. Except if we already hit a limit of parallel * queries for this connection. */ if ((!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size) && set_size(s->queries) < DNS_QUERIES_PER_STREAM) f |= EPOLLIN; #if ENABLE_DNS_OVER_TLS /* For handshake and clean closing purposes, TLS can override requested events */ if (s->dnstls_events != 0) f = s->dnstls_events; #endif return sd_event_source_set_io_events(s->io_event_source, f); } static int dns_stream_complete(DnsStream *s, int error) { _cleanup_(dns_stream_unrefp) _unused_ DnsStream *ref = dns_stream_ref(s); /* Protect stream while we process it */ assert(s); assert(error >= 0); /* Error is > 0 when the connection failed for some reason in the network stack. It's == 0 if we sent * and received exactly one packet each (in the LLMNR client case). */ #if ENABLE_DNS_OVER_TLS if (s->encrypted) { int r; r = dnstls_stream_shutdown(s, error); if (r != -EAGAIN) dns_stream_stop(s); } else #endif dns_stream_stop(s); dns_stream_detach(s); if (s->complete) s->complete(s, error); else /* the default action if no completion function is set is to close the stream */ dns_stream_unref(s); return 0; } static int dns_stream_identify(DnsStream *s) { CMSG_BUFFER_TYPE(CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo)) + CMSG_SPACE(int) + /* for the TTL */ + EXTRA_CMSG_SPACE /* kernel appears to require extra space */) control; struct msghdr mh = {}; struct cmsghdr *cmsg; socklen_t sl; int r; assert(s); if (s->identified) return 0; /* Query the local side */ s->local_salen = sizeof(s->local); r = getsockname(s->fd, &s->local.sa, &s->local_salen); if (r < 0) return -errno; if (s->local.sa.sa_family == AF_INET6 && s->ifindex <= 0) s->ifindex = s->local.in6.sin6_scope_id; /* Query the remote side */ s->peer_salen = sizeof(s->peer); r = getpeername(s->fd, &s->peer.sa, &s->peer_salen); if (r < 0) return -errno; if (s->peer.sa.sa_family == AF_INET6 && s->ifindex <= 0) s->ifindex = s->peer.in6.sin6_scope_id; /* Check consistency */ assert(s->peer.sa.sa_family == s->local.sa.sa_family); assert(IN_SET(s->peer.sa.sa_family, AF_INET, AF_INET6)); /* Query connection meta information */ sl = sizeof(control); if (s->peer.sa.sa_family == AF_INET) { r = getsockopt(s->fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl); if (r < 0) return -errno; } else if (s->peer.sa.sa_family == AF_INET6) { r = getsockopt(s->fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl); if (r < 0) return -errno; } else return -EAFNOSUPPORT; mh.msg_control = &control; mh.msg_controllen = sl; CMSG_FOREACH(cmsg, &mh) { if (cmsg->cmsg_level == IPPROTO_IPV6) { assert(s->peer.sa.sa_family == AF_INET6); switch (cmsg->cmsg_type) { case IPV6_PKTINFO: { struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg); if (s->ifindex <= 0) s->ifindex = i->ipi6_ifindex; break; } case IPV6_HOPLIMIT: s->ttl = *(int *) CMSG_DATA(cmsg); break; } } else if (cmsg->cmsg_level == IPPROTO_IP) { assert(s->peer.sa.sa_family == AF_INET); switch (cmsg->cmsg_type) { case IP_PKTINFO: { struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg); if (s->ifindex <= 0) s->ifindex = i->ipi_ifindex; break; } case IP_TTL: s->ttl = *(int *) CMSG_DATA(cmsg); break; } } } /* The Linux kernel sets the interface index to the loopback * device if the connection came from the local host since it * avoids the routing table in such a case. Let's unset the * interface index in such a case. */ if (s->ifindex == LOOPBACK_IFINDEX) s->ifindex = 0; /* If we don't know the interface index still, we look for the * first local interface with a matching address. Yuck! */ if (s->ifindex <= 0) 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); if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) { /* Make sure all packets for this connection are sent on the same interface */ r = socket_set_unicast_if(s->fd, s->local.sa.sa_family, s->ifindex); if (r < 0) log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF/IPV6_UNICAST_IF: %m"); } s->identified = true; return 0; } ssize_t dns_stream_writev(DnsStream *s, const struct iovec *iov, size_t iovcnt, int flags) { ssize_t m; assert(s); assert(iov); #if ENABLE_DNS_OVER_TLS if (s->encrypted && !(flags & DNS_STREAM_WRITE_TLS_DATA)) { ssize_t ss; size_t i; m = 0; for (i = 0; i < iovcnt; i++) { ss = dnstls_stream_write(s, iov[i].iov_base, iov[i].iov_len); if (ss < 0) return ss; m += ss; if (ss != (ssize_t) iov[i].iov_len) continue; } } else #endif if (s->tfo_salen > 0) { struct msghdr hdr = { .msg_iov = (struct iovec*) iov, .msg_iovlen = iovcnt, .msg_name = &s->tfo_address.sa, .msg_namelen = s->tfo_salen }; m = sendmsg(s->fd, &hdr, MSG_FASTOPEN); if (m < 0) { if (errno == EOPNOTSUPP) { s->tfo_salen = 0; if (connect(s->fd, &s->tfo_address.sa, s->tfo_salen) < 0) return -errno; return -EAGAIN; } if (errno == EINPROGRESS) return -EAGAIN; return -errno; } else s->tfo_salen = 0; /* connection is made */ } else { m = writev(s->fd, iov, iovcnt); if (m < 0) return -errno; } return m; } static ssize_t dns_stream_read(DnsStream *s, void *buf, size_t count) { ssize_t ss; #if ENABLE_DNS_OVER_TLS if (s->encrypted) ss = dnstls_stream_read(s, buf, count); else #endif { ss = read(s->fd, buf, count); if (ss < 0) return -errno; } return ss; } static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) { DnsStream *s = userdata; assert(s); return dns_stream_complete(s, ETIMEDOUT); } static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *userdata) { _cleanup_(dns_stream_unrefp) DnsStream *s = dns_stream_ref(userdata); /* Protect stream while we process it */ bool progressed = false; int r; assert(s); #if ENABLE_DNS_OVER_TLS if (s->encrypted) { r = dnstls_stream_on_io(s, revents); if (r == DNSTLS_STREAM_CLOSED) return 0; if (r == -EAGAIN) return dns_stream_update_io(s); if (r < 0) return dns_stream_complete(s, -r); r = dns_stream_update_io(s); if (r < 0) return r; } #endif /* only identify after connecting */ if (s->tfo_salen == 0) { r = dns_stream_identify(s); if (r < 0) return dns_stream_complete(s, -r); } if ((revents & EPOLLOUT) && s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size) { struct iovec iov[2]; ssize_t ss; iov[0] = IOVEC_MAKE(&s->write_size, sizeof(s->write_size)); iov[1] = IOVEC_MAKE(DNS_PACKET_DATA(s->write_packet), s->write_packet->size); IOVEC_INCREMENT(iov, 2, s->n_written); ss = dns_stream_writev(s, iov, 2, 0); if (ss < 0) { if (!IN_SET(-ss, EINTR, EAGAIN)) return dns_stream_complete(s, -ss); } else { progressed = true; s->n_written += ss; } /* Are we done? If so, disable the event source for EPOLLOUT */ if (s->n_written >= sizeof(s->write_size) + s->write_packet->size) { r = dns_stream_update_io(s); if (r < 0) return dns_stream_complete(s, -r); } } if ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) && (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size)) { if (s->n_read < sizeof(s->read_size)) { ssize_t ss; ss = dns_stream_read(s, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read); if (ss < 0) { if (!IN_SET(-ss, EINTR, EAGAIN)) return dns_stream_complete(s, -ss); } else if (ss == 0) return dns_stream_complete(s, ECONNRESET); else { progressed = true; s->n_read += ss; } } if (s->n_read >= sizeof(s->read_size)) { if (be16toh(s->read_size) < DNS_PACKET_HEADER_SIZE) return dns_stream_complete(s, EBADMSG); if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) { ssize_t ss; if (!s->read_packet) { r = dns_packet_new(&s->read_packet, s->protocol, be16toh(s->read_size), DNS_PACKET_SIZE_MAX); if (r < 0) return dns_stream_complete(s, -r); s->read_packet->size = be16toh(s->read_size); s->read_packet->ipproto = IPPROTO_TCP; s->read_packet->family = s->peer.sa.sa_family; s->read_packet->ttl = s->ttl; s->read_packet->ifindex = s->ifindex; if (s->read_packet->family == AF_INET) { s->read_packet->sender.in = s->peer.in.sin_addr; s->read_packet->sender_port = be16toh(s->peer.in.sin_port); s->read_packet->destination.in = s->local.in.sin_addr; s->read_packet->destination_port = be16toh(s->local.in.sin_port); } else { assert(s->read_packet->family == AF_INET6); s->read_packet->sender.in6 = s->peer.in6.sin6_addr; s->read_packet->sender_port = be16toh(s->peer.in6.sin6_port); s->read_packet->destination.in6 = s->local.in6.sin6_addr; s->read_packet->destination_port = be16toh(s->local.in6.sin6_port); if (s->read_packet->ifindex == 0) s->read_packet->ifindex = s->peer.in6.sin6_scope_id; if (s->read_packet->ifindex == 0) s->read_packet->ifindex = s->local.in6.sin6_scope_id; } } ss = dns_stream_read(s, (uint8_t*) DNS_PACKET_DATA(s->read_packet) + s->n_read - sizeof(s->read_size), sizeof(s->read_size) + be16toh(s->read_size) - s->n_read); if (ss < 0) { if (!IN_SET(-ss, EINTR, EAGAIN)) return dns_stream_complete(s, -ss); } else if (ss == 0) return dns_stream_complete(s, ECONNRESET); else s->n_read += ss; } /* Are we done? If so, disable the event source for EPOLLIN */ if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) { /* If there's a packet handler * installed, call that. Note that * this is optional... */ if (s->on_packet) { r = s->on_packet(s); if (r < 0) return r; } r = dns_stream_update_io(s); if (r < 0) return dns_stream_complete(s, -r); } } } /* Call "complete" callback if finished reading and writing one packet, and there's nothing else left * to write. */ if (s->type == DNS_STREAM_LLMNR_SEND && (s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) && ordered_set_isempty(s->write_queue) && (s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size)) return dns_stream_complete(s, 0); /* If we did something, let's restart the timeout event source */ if (progressed && s->timeout_event_source) { r = sd_event_source_set_time_relative(s->timeout_event_source, DNS_STREAM_TIMEOUT_USEC); if (r < 0) log_warning_errno(errno, "Couldn't restart TCP connection timeout, ignoring: %m"); } return 0; } static DnsStream *dns_stream_free(DnsStream *s) { DnsPacket *p; assert(s); dns_stream_stop(s); if (s->manager) { LIST_REMOVE(streams, s->manager->dns_streams, s); s->manager->n_dns_streams[s->type]--; } #if ENABLE_DNS_OVER_TLS if (s->encrypted) dnstls_stream_free(s); #endif ORDERED_SET_FOREACH(p, s->write_queue) dns_packet_unref(ordered_set_remove(s->write_queue, p)); dns_packet_unref(s->write_packet); dns_packet_unref(s->read_packet); dns_server_unref(s->server); ordered_set_free(s->write_queue); return mfree(s); } DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsStream, dns_stream, dns_stream_free); int dns_stream_new( Manager *m, DnsStream **ret, DnsStreamType type, DnsProtocol protocol, int fd, const union sockaddr_union *tfo_address) { _cleanup_(dns_stream_unrefp) DnsStream *s = NULL; int r; assert(m); assert(ret); assert(type >= 0); assert(type < _DNS_STREAM_TYPE_MAX); assert(protocol >= 0); assert(protocol < _DNS_PROTOCOL_MAX); assert(fd >= 0); if (m->n_dns_streams[type] > DNS_STREAMS_MAX) return -EBUSY; s = new(DnsStream, 1); if (!s) return -ENOMEM; *s = (DnsStream) { .n_ref = 1, .fd = -1, .protocol = protocol, .type = type, }; r = ordered_set_ensure_allocated(&s->write_queue, &dns_packet_hash_ops); if (r < 0) return r; r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s); if (r < 0) return r; (void) sd_event_source_set_description(s->io_event_source, "dns-stream-io"); r = sd_event_add_time_relative( m->event, &s->timeout_event_source, clock_boottime_or_monotonic(), DNS_STREAM_TIMEOUT_USEC, 0, on_stream_timeout, s); if (r < 0) return r; (void) sd_event_source_set_description(s->timeout_event_source, "dns-stream-timeout"); LIST_PREPEND(streams, m->dns_streams, s); m->n_dns_streams[type]++; s->manager = m; s->fd = fd; if (tfo_address) { s->tfo_address = *tfo_address; s->tfo_salen = tfo_address->sa.sa_family == AF_INET6 ? sizeof(tfo_address->in6) : sizeof(tfo_address->in); } *ret = TAKE_PTR(s); return 0; } int dns_stream_write_packet(DnsStream *s, DnsPacket *p) { int r; assert(s); assert(p); r = ordered_set_put(s->write_queue, p); if (r < 0) return r; dns_packet_ref(p); return dns_stream_update_io(s); } DnsPacket *dns_stream_take_read_packet(DnsStream *s) { assert(s); if (!s->read_packet) return NULL; if (s->n_read < sizeof(s->read_size)) return NULL; if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) return NULL; s->n_read = 0; return TAKE_PTR(s->read_packet); } void dns_stream_detach(DnsStream *s) { assert(s); if (!s->server) return; if (s->server->stream != s) return; dns_server_unref_stream(s->server); }