X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fresolve%2Fresolved-dns-scope.c;h=abdb2e07325e2b4d80d81706dbb9f10c2aa28c0d;hp=190c5f41af1d20c8ffdc71d69236ccb1d704952b;hb=d076c6f9e486587d634d59082d2a13b9cbb4aef3;hpb=901fd8164797f3eeb9921c85915dc409d49ab5d8 diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c index 190c5f41a..abdb2e073 100644 --- a/src/resolve/resolved-dns-scope.c +++ b/src/resolve/resolved-dns-scope.c @@ -21,13 +21,15 @@ #include +#include "missing.h" #include "strv.h" #include "socket-util.h" #include "af-list.h" #include "resolved-dns-domain.h" #include "resolved-dns-scope.h" -#define SEND_TIMEOUT_USEC (2*USEC_PER_SEC) +#define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC) +#define MULTICAST_RATELIMIT_BURST 1000 int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int family) { DnsScope *s; @@ -50,11 +52,17 @@ int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int log_debug("New scope on link %s, protocol %s, family %s", l ? l->name : "*", dns_protocol_to_string(protocol), family == AF_UNSPEC ? "*" : af_to_name(family)); + /* Enforce ratelimiting for the multicast protocols */ + RATELIMIT_INIT(s->ratelimit, MULTICAST_RATELIMIT_INTERVAL_USEC, MULTICAST_RATELIMIT_BURST); + *ret = s; return 0; } DnsScope* dns_scope_free(DnsScope *s) { + DnsTransaction *t; + DnsResourceRecord *rr; + if (!s) return NULL; @@ -62,16 +70,26 @@ DnsScope* dns_scope_free(DnsScope *s) { dns_scope_llmnr_membership(s, false); - while (s->transactions) { - DnsQuery *q; + while ((t = s->transactions)) { - q = s->transactions->query; - dns_query_transaction_free(s->transactions); + /* Abort the transaction, but make sure it is not + * freed while we still look at it */ - dns_query_finish(q); + t->block_gc++; + dns_transaction_complete(t, DNS_TRANSACTION_ABORTED); + t->block_gc--; + + dns_transaction_free(t); } + while ((rr = ordered_hashmap_steal_first(s->conflict_queue))) + dns_resource_record_unref(rr); + + ordered_hashmap_free(s->conflict_queue); + sd_event_source_unref(s->conflict_event_source); + dns_cache_flush(&s->cache); + dns_zone_flush(&s->zone); LIST_REMOVE(scopes, s->manager->dns_scopes, s); strv_free(s->domains); @@ -80,7 +98,7 @@ DnsScope* dns_scope_free(DnsScope *s) { return NULL; } -DnsServer *dns_scope_get_server(DnsScope *s) { +DnsServer *dns_scope_get_dns_server(DnsScope *s) { assert(s); if (s->protocol != DNS_PROTOCOL_DNS) @@ -104,7 +122,7 @@ void dns_scope_next_dns_server(DnsScope *s) { manager_next_dns_server(s->manager); } -int dns_scope_send(DnsScope *s, DnsPacket *p) { +int dns_scope_emit(DnsScope *s, DnsPacket *p) { union in_addr_union addr; int ifindex = 0, r; int family; @@ -125,7 +143,10 @@ int dns_scope_send(DnsScope *s, DnsPacket *p) { if (s->protocol == DNS_PROTOCOL_DNS) { DnsServer *srv; - srv = dns_scope_get_server(s); + if (DNS_PACKET_QDCOUNT(p) > 1) + return -ENOTSUP; + + srv = dns_scope_get_dns_server(s); if (!srv) return -ESRCH; @@ -153,17 +174,18 @@ int dns_scope_send(DnsScope *s, DnsPacket *p) { if (DNS_PACKET_QDCOUNT(p) > 1) return -ENOTSUP; + if (!ratelimit_test(&s->ratelimit)) + return -EBUSY; + family = s->family; port = 5355; if (family == AF_INET) { addr.in = LLMNR_MULTICAST_IPV4_ADDRESS; - /* fd = manager_dns_ipv4_fd(s->manager); */ fd = manager_llmnr_ipv4_udp_fd(s->manager); } else if (family == AF_INET6) { addr.in6 = LLMNR_MULTICAST_IPV6_ADDRESS; fd = manager_llmnr_ipv6_udp_fd(s->manager); - /* fd = manager_dns_ipv6_fd(s->manager); */ } else return -EAFNOSUPPORT; if (fd < 0) @@ -178,39 +200,86 @@ int dns_scope_send(DnsScope *s, DnsPacket *p) { return 1; } -int dns_scope_tcp_socket(DnsScope *s) { +int dns_scope_tcp_socket(DnsScope *s, int family, const union in_addr_union *address, uint16_t port) { _cleanup_close_ int fd = -1; union sockaddr_union sa = {}; socklen_t salen; - int one, ret; - DnsServer *srv; - int r; + static const int one = 1; + int ret, r; assert(s); + assert((family == AF_UNSPEC) == !address); - srv = dns_scope_get_server(s); - if (!srv) - return -ESRCH; - - sa.sa.sa_family = srv->family; - if (srv->family == AF_INET) { - sa.in.sin_port = htobe16(53); - sa.in.sin_addr = srv->address.in; - salen = sizeof(sa.in); - } else if (srv->family == AF_INET6) { - sa.in6.sin6_port = htobe16(53); - sa.in6.sin6_addr = srv->address.in6; - sa.in6.sin6_scope_id = s->link ? s->link->ifindex : 0; - salen = sizeof(sa.in6); - } else - return -EAFNOSUPPORT; + if (family == AF_UNSPEC) { + DnsServer *srv; + + srv = dns_scope_get_dns_server(s); + if (!srv) + return -ESRCH; + + sa.sa.sa_family = srv->family; + if (srv->family == AF_INET) { + sa.in.sin_port = htobe16(port); + sa.in.sin_addr = srv->address.in; + salen = sizeof(sa.in); + } else if (srv->family == AF_INET6) { + sa.in6.sin6_port = htobe16(port); + sa.in6.sin6_addr = srv->address.in6; + sa.in6.sin6_scope_id = s->link ? s->link->ifindex : 0; + salen = sizeof(sa.in6); + } else + return -EAFNOSUPPORT; + } else { + sa.sa.sa_family = family; + + if (family == AF_INET) { + sa.in.sin_port = htobe16(port); + sa.in.sin_addr = address->in; + salen = sizeof(sa.in); + } else if (family == AF_INET6) { + sa.in6.sin6_port = htobe16(port); + sa.in6.sin6_addr = address->in6; + sa.in6.sin6_scope_id = s->link ? s->link->ifindex : 0; + salen = sizeof(sa.in6); + } else + return -EAFNOSUPPORT; + } - fd = socket(srv->family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + fd = socket(sa.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (fd < 0) return -errno; - one = 1; - setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)); + r = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)); + if (r < 0) + return -errno; + + if (s->link) { + uint32_t ifindex = htobe32(s->link->ifindex); + + if (sa.sa.sa_family == AF_INET) { + r = setsockopt(fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex)); + if (r < 0) + return -errno; + } else if (sa.sa.sa_family == AF_INET6) { + r = setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex)); + if (r < 0) + return -errno; + } + } + + if (s->protocol == DNS_PROTOCOL_LLMNR) { + /* RFC 4795, section 2.5 requires the TTL to be set to 1 */ + + if (sa.sa.sa_family == AF_INET) { + r = setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof(one)); + if (r < 0) + return -errno; + } else if (sa.sa.sa_family == AF_INET6) { + r = setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one)); + if (r < 0) + return -errno; + } + } r = connect(fd, &sa.sa, salen); if (r < 0 && errno != EINPROGRESS) @@ -218,47 +287,55 @@ int dns_scope_tcp_socket(DnsScope *s) { ret = fd; fd = -1; + return ret; } -DnsScopeMatch dns_scope_good_domain(DnsScope *s, const char *domain) { +DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, const char *domain) { char **i; assert(s); assert(domain); + if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex)) + return DNS_SCOPE_NO; + + if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family) & flags) == 0) + return DNS_SCOPE_NO; + STRV_FOREACH(i, s->domains) - if (dns_name_endswith(domain, *i)) + if (dns_name_endswith(domain, *i) > 0) return DNS_SCOPE_YES; - if (dns_name_root(domain)) + if (dns_name_root(domain) != 0) return DNS_SCOPE_NO; if (is_localhost(domain)) return DNS_SCOPE_NO; if (s->protocol == DNS_PROTOCOL_DNS) { - if (dns_name_endswith(domain, "254.169.in-addr.arpa") || - dns_name_endswith(domain, "0.8.e.f.ip6.arpa") || - dns_name_single_label(domain)) - return DNS_SCOPE_NO; + if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 && + dns_name_endswith(domain, "0.8.e.f.ip6.arpa") == 0 && + dns_name_single_label(domain) == 0) + return DNS_SCOPE_MAYBE; - return DNS_SCOPE_MAYBE; + return DNS_SCOPE_NO; } if (s->protocol == DNS_PROTOCOL_MDNS) { - if (dns_name_endswith(domain, "254.169.in-addr.arpa") || - dns_name_endswith(domain, "0.8.e.f.ip6.arpa") || - dns_name_endswith(domain, "local")) + if (dns_name_endswith(domain, "254.169.in-addr.arpa") > 0 || + dns_name_endswith(domain, "0.8.e.f.ip6.arpa") > 0 || + (dns_name_endswith(domain, "local") > 0 && dns_name_equal(domain, "local") == 0)) return DNS_SCOPE_MAYBE; return DNS_SCOPE_NO; } if (s->protocol == DNS_PROTOCOL_LLMNR) { - if (dns_name_endswith(domain, "254.169.in-addr.arpa") || - dns_name_endswith(domain, "0.8.e.f.ip6.arpa") || - dns_name_single_label(domain)) + if (dns_name_endswith(domain, "in-addr.arpa") > 0 || + dns_name_endswith(domain, "ip6.arpa") > 0 || + (dns_name_single_label(domain) > 0 && + dns_name_equal(domain, "gateway") <= 0)) /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */ return DNS_SCOPE_MAYBE; return DNS_SCOPE_NO; @@ -289,6 +366,13 @@ int dns_scope_good_key(DnsScope *s, DnsResourceKey *key) { int dns_scope_llmnr_membership(DnsScope *s, bool b) { int fd; + assert(s); + + if (s->protocol != DNS_PROTOCOL_LLMNR) + return 0; + + assert(s->link); + if (s->family == AF_INET) { struct ip_mreqn mreqn = { .imr_multiaddr = LLMNR_MULTICAST_IPV4_ADDRESS, @@ -299,6 +383,12 @@ int dns_scope_llmnr_membership(DnsScope *s, bool b) { if (fd < 0) return fd; + /* Always first try to drop membership before we add + * one. This is necessary on some devices, such as + * veth. */ + if (b) + (void)setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)); + if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0) return -errno; @@ -312,6 +402,9 @@ int dns_scope_llmnr_membership(DnsScope *s, bool b) { if (fd < 0) return fd; + if (b) + (void)setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)); + if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) return -errno; } else @@ -319,3 +412,383 @@ int dns_scope_llmnr_membership(DnsScope *s, bool b) { return 0; } + +int dns_scope_good_dns_server(DnsScope *s, int family, const union in_addr_union *address) { + assert(s); + assert(address); + + if (s->protocol != DNS_PROTOCOL_DNS) + return 1; + + if (s->link) + return !!link_find_dns_server(s->link, family, address); + else + return !!manager_find_dns_server(s->manager, family, address); +} + +static int dns_scope_make_reply_packet( + DnsScope *s, + uint16_t id, + int rcode, + DnsQuestion *q, + DnsAnswer *answer, + DnsAnswer *soa, + bool tentative, + DnsPacket **ret) { + + _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; + unsigned i; + int r; + + assert(s); + assert(ret); + + if ((!q || q->n_keys <= 0) + && (!answer || answer->n_rrs <= 0) + && (!soa || soa->n_rrs <= 0)) + return -EINVAL; + + r = dns_packet_new(&p, s->protocol, 0); + if (r < 0) + return r; + + DNS_PACKET_HEADER(p)->id = id; + DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( + 1 /* qr */, + 0 /* opcode */, + 0 /* c */, + 0 /* tc */, + tentative, + 0 /* (ra) */, + 0 /* (ad) */, + 0 /* (cd) */, + rcode)); + + if (q) { + for (i = 0; i < q->n_keys; i++) { + r = dns_packet_append_key(p, q->keys[i], NULL); + if (r < 0) + return r; + } + + DNS_PACKET_HEADER(p)->qdcount = htobe16(q->n_keys); + } + + if (answer) { + for (i = 0; i < answer->n_rrs; i++) { + r = dns_packet_append_rr(p, answer->rrs[i], NULL); + if (r < 0) + return r; + } + + DNS_PACKET_HEADER(p)->ancount = htobe16(answer->n_rrs); + } + + if (soa) { + for (i = 0; i < soa->n_rrs; i++) { + r = dns_packet_append_rr(p, soa->rrs[i], NULL); + if (r < 0) + return r; + } + + DNS_PACKET_HEADER(p)->arcount = htobe16(soa->n_rrs); + } + + *ret = p; + p = NULL; + + return 0; +} + +static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) { + unsigned n; + + assert(s); + assert(p); + + if (p->question) + for (n = 0; n < p->question->n_keys; n++) + dns_zone_verify_conflicts(&s->zone, p->question->keys[n]); + if (p->answer) + for (n = 0; n < p->answer->n_rrs; n++) + dns_zone_verify_conflicts(&s->zone, p->answer->rrs[n]->key); +} + +void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) { + _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; + _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL; + bool tentative = false; + int r, fd; + + assert(s); + assert(p); + + if (p->protocol != DNS_PROTOCOL_LLMNR) + return; + + if (p->ipproto == IPPROTO_UDP) { + /* Don't accept UDP queries directed to anything but + * the LLMNR multicast addresses. See RFC 4795, + * section 2.5. */ + + if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS)) + return; + + if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV6_ADDRESS)) + return; + } + + r = dns_packet_extract(p); + if (r < 0) { + log_debug_errno(r, "Failed to extract resources from incoming packet: %m"); + return; + } + + if (DNS_PACKET_C(p)) { + /* Somebody notified us about a possible conflict */ + dns_scope_verify_conflicts(s, p); + return; + } + + r = dns_zone_lookup(&s->zone, p->question, &answer, &soa, &tentative); + if (r < 0) { + log_debug_errno(r, "Failed to lookup key: %m"); + return; + } + if (r == 0) + return; + + if (answer) + dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0); + + r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply); + if (r < 0) { + log_debug_errno(r, "Failed to build reply packet: %m"); + return; + } + + if (stream) + r = dns_stream_write_packet(stream, reply); + else { + if (!ratelimit_test(&s->ratelimit)) + return; + + if (p->family == AF_INET) + fd = manager_llmnr_ipv4_udp_fd(s->manager); + else if (p->family == AF_INET6) + fd = manager_llmnr_ipv6_udp_fd(s->manager); + else { + log_debug("Unknown protocol"); + return; + } + if (fd < 0) { + log_debug_errno(fd, "Failed to get reply socket: %m"); + return; + } + + /* Note that we always immediately reply to all LLMNR + * requests, and do not wait any time, since we + * verified uniqueness for all records. Also see RFC + * 4795, Section 2.7 */ + + r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, reply); + } + + if (r < 0) { + log_debug_errno(r, "Failed to send reply packet: %m"); + return; + } +} + +DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsQuestion *question, bool cache_ok) { + DnsTransaction *t; + + assert(scope); + assert(question); + + /* Try to find an ongoing transaction that is a equal or a + * superset of the specified question */ + + LIST_FOREACH(transactions_by_scope, t, scope->transactions) { + + /* Refuse reusing transactions that completed based on + * cached data instead of a real packet, if that's + * requested. */ + if (!cache_ok && + IN_SET(t->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_FAILURE) && + !t->received) + continue; + + if (dns_question_is_superset(t->question, question) > 0) + return t; + } + + return NULL; +} + +static int dns_scope_make_conflict_packet( + DnsScope *s, + DnsResourceRecord *rr, + DnsPacket **ret) { + + _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; + int r; + + assert(s); + assert(rr); + assert(ret); + + r = dns_packet_new(&p, s->protocol, 0); + if (r < 0) + return r; + + DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( + 0 /* qr */, + 0 /* opcode */, + 1 /* conflict */, + 0 /* tc */, + 0 /* t */, + 0 /* (ra) */, + 0 /* (ad) */, + 0 /* (cd) */, + 0)); + random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t)); + DNS_PACKET_HEADER(p)->qdcount = htobe16(1); + DNS_PACKET_HEADER(p)->arcount = htobe16(1); + + r = dns_packet_append_key(p, rr->key, NULL); + if (r < 0) + return r; + + r = dns_packet_append_rr(p, rr, NULL); + if (r < 0) + return r; + + *ret = p; + p = NULL; + + return 0; +} + +static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) { + DnsScope *scope = userdata; + int r; + + assert(es); + assert(scope); + + scope->conflict_event_source = sd_event_source_unref(scope->conflict_event_source); + + for (;;) { + _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; + _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; + + rr = ordered_hashmap_steal_first(scope->conflict_queue); + if (!rr) + break; + + r = dns_scope_make_conflict_packet(scope, rr, &p); + if (r < 0) { + log_error_errno(r, "Failed to make conflict packet: %m"); + return 0; + } + + r = dns_scope_emit(scope, p); + if (r < 0) + log_debug_errno(r, "Failed to send conflict packet: %m"); + } + + return 0; +} + +int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) { + usec_t jitter; + int r; + + assert(scope); + assert(rr); + + /* We don't send these queries immediately. Instead, we queue + * them, and send them after some jitter delay. */ + r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops); + if (r < 0) { + log_oom(); + return r; + } + + /* We only place one RR per key in the conflict + * messages, not all of them. That should be enough to + * indicate where there might be a conflict */ + r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr); + if (r == -EEXIST || r == 0) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to queue conflicting RR: %m"); + + dns_resource_record_ref(rr); + + if (scope->conflict_event_source) + return 0; + + random_bytes(&jitter, sizeof(jitter)); + jitter %= LLMNR_JITTER_INTERVAL_USEC; + + r = sd_event_add_time(scope->manager->event, + &scope->conflict_event_source, + clock_boottime_or_monotonic(), + now(clock_boottime_or_monotonic()) + jitter, + LLMNR_JITTER_INTERVAL_USEC, + on_conflict_dispatch, scope); + if (r < 0) + return log_debug_errno(r, "Failed to add conflict dispatch event: %m"); + + return 0; +} + +void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) { + unsigned i; + int r; + + assert(scope); + assert(p); + + if (p->protocol != DNS_PROTOCOL_LLMNR) + return; + + if (DNS_PACKET_RRCOUNT(p) <= 0) + return; + + if (DNS_PACKET_C(p) != 0) + return; + + if (DNS_PACKET_T(p) != 0) + return; + + if (manager_our_packet(scope->manager, p)) + return; + + r = dns_packet_extract(p); + if (r < 0) { + log_debug_errno(r, "Failed to extract packet: %m"); + return; + } + + log_debug("Checking for conflicts..."); + + for (i = 0; i < p->answer->n_rrs; i++) { + + /* Check for conflicts against the local zone. If we + * found one, we won't check any further */ + r = dns_zone_check_conflicts(&scope->zone, p->answer->rrs[i]); + if (r != 0) + continue; + + /* Check for conflicts against the local cache. If so, + * send out an advisory query, to inform everybody */ + r = dns_cache_check_conflicts(&scope->cache, p->answer->rrs[i], p->family, &p->sender); + if (r <= 0) + continue; + + dns_scope_notify_conflict(scope, p->answer->rrs[i]); + } +}