./tools/notsd-move

1 files changed, 539 insertions, 0 deletions

diff --git a/src/grp-resolve/systemd-resolved/resolved-dns-stub.c b/src/grp-resolve/systemd-resolved/resolved-dns-stub.c
new file mode 100644
index 0000000000..ad49862a70
--- /dev/null
+++ b/src/grp-resolve/systemd-resolved/resolved-dns-stub.c
@@ -0,0 +1,539 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "systemd-basic/fd-util.h"
+#include "systemd-basic/socket-util.h"
+
+#include "resolved-dns-stub.h"
+
+/* The MTU of the loopback device is 64K on Linux, advertise that as maximum datagram size, but subtract the Ethernet,
+ * IP and UDP header sizes */
+#define ADVERTISE_DATAGRAM_SIZE_MAX (65536U-14U-20U-8U)
+
+static int manager_dns_stub_udp_fd(Manager *m);
+static int manager_dns_stub_tcp_fd(Manager *m);
+
+static int dns_stub_make_reply_packet(
+                uint16_t id,
+                int rcode,
+                DnsQuestion *q,
+                DnsAnswer *answer,
+                bool add_opt,   /* add an OPT RR to this packet */
+                bool edns0_do,  /* set the EDNS0 DNSSEC OK bit */
+                bool ad,        /* set the DNSSEC authenticated data bit */
+                DnsPacket **ret) {
+
+        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+        DnsResourceRecord *rr;
+        unsigned c = 0;
+        int r;
+
+        /* Note that we don't bother with any additional RRs, as this is stub is for local lookups only, and hence
+         * roundtrips aren't expensive. */
+
+        r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0);
+        if (r < 0)
+                return r;
+
+        /* If the client didn't do EDNS, clamp the rcode to 4 bit */
+        if (!add_opt && rcode > 0xF)
+                rcode = DNS_RCODE_SERVFAIL;
+
+        DNS_PACKET_HEADER(p)->id = id;
+        DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
+                                                              1 /* qr */,
+                                                              0 /* opcode */,
+                                                              0 /* aa */,
+                                                              0 /* tc */,
+                                                              1 /* rd */,
+                                                              1 /* ra */,
+                                                              ad /* ad */,
+                                                              0 /* cd */,
+                                                              rcode));
+
+        r = dns_packet_append_question(p, q);
+        if (r < 0)
+                return r;
+        DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q));
+
+        DNS_ANSWER_FOREACH(rr, answer) {
+                r = dns_question_matches_rr(q, rr, NULL);
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        goto add;
+
+                r = dns_question_matches_cname_or_dname(q, rr, NULL);
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        goto add;
+
+                continue;
+        add:
+                r = dns_packet_append_rr(p, rr, NULL, NULL);
+                if (r < 0)
+                        return r;
+
+                c++;
+        }
+        DNS_PACKET_HEADER(p)->ancount = htobe16(c);
+
+        if (add_opt) {
+                r = dns_packet_append_opt(p, ADVERTISE_DATAGRAM_SIZE_MAX, edns0_do, rcode, NULL);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = p;
+        p = NULL;
+
+        return 0;
+}
+
+static void dns_stub_detach_stream(DnsStream *s) {
+        assert(s);
+
+        s->complete = NULL;
+        s->on_packet = NULL;
+        s->query = NULL;
+}
+
+static int dns_stub_send(Manager *m, DnsStream *s, DnsPacket *p, DnsPacket *reply) {
+        int r;
+
+        assert(m);
+        assert(p);
+        assert(reply);
+
+        if (s)
+                r = dns_stream_write_packet(s, reply);
+        else {
+                int fd;
+
+                /* Truncate the message to the right size */
+                if (reply->size > DNS_PACKET_PAYLOAD_SIZE_MAX(p)) {
+                        dns_packet_truncate(reply, DNS_PACKET_UNICAST_SIZE_MAX);
+                        DNS_PACKET_HEADER(reply)->flags = htobe16(be16toh(DNS_PACKET_HEADER(reply)->flags) | DNS_PACKET_FLAG_TC);
+                }
+
+                fd = manager_dns_stub_udp_fd(m);
+                if (fd < 0)
+                        return log_debug_errno(fd, "Failed to get reply socket: %m");
+
+                /* Note that it is essential here that we explicitly choose the source IP address for this packet. This
+                 * is because otherwise the kernel will choose it automatically based on the routing table and will
+                 * thus pick 127.0.0.1 rather than 127.0.0.53. */
+
+                r = manager_send(m, fd, LOOPBACK_IFINDEX, p->family, &p->sender, p->sender_port, &p->destination, reply);
+        }
+        if (r < 0)
+                return log_debug_errno(r, "Failed to send reply packet: %m");
+
+        return 0;
+}
+
+static int dns_stub_send_failure(Manager *m, DnsStream *s, DnsPacket *p, int rcode) {
+        _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
+        int r;
+
+        assert(m);
+        assert(p);
+
+        r = dns_stub_make_reply_packet(DNS_PACKET_ID(p), rcode, p->question, NULL, !!p->opt, DNS_PACKET_DO(p), false, &reply);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to build failure packet: %m");
+
+        return dns_stub_send(m, s, p, reply);
+}
+
+static void dns_stub_query_complete(DnsQuery *q) {
+        int r;
+
+        assert(q);
+        assert(q->request_dns_packet);
+
+        switch (q->state) {
+
+        case DNS_TRANSACTION_SUCCESS: {
+                _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
+
+                r = dns_stub_make_reply_packet(
+                                DNS_PACKET_ID(q->request_dns_packet),
+                                q->answer_rcode,
+                                q->question_idna,
+                                q->answer,
+                                !!q->request_dns_packet->opt,
+                                DNS_PACKET_DO(q->request_dns_packet),
+                                DNS_PACKET_DO(q->request_dns_packet) && q->answer_authenticated,
+                                &reply);
+                if (r < 0) {
+                        log_debug_errno(r, "Failed to build reply packet: %m");
+                        break;
+                }
+
+                (void) dns_stub_send(q->manager, q->request_dns_stream, q->request_dns_packet, reply);
+                break;
+        }
+
+        case DNS_TRANSACTION_RCODE_FAILURE:
+                (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, q->answer_rcode);
+                break;
+
+        case DNS_TRANSACTION_NOT_FOUND:
+                (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_NXDOMAIN);
+                break;
+
+        case DNS_TRANSACTION_TIMEOUT:
+        case DNS_TRANSACTION_ATTEMPTS_MAX_REACHED:
+                /* Propagate a timeout as a no packet, i.e. that the client also gets a timeout */
+                break;
+
+        case DNS_TRANSACTION_NO_SERVERS:
+        case DNS_TRANSACTION_INVALID_REPLY:
+        case DNS_TRANSACTION_ERRNO:
+        case DNS_TRANSACTION_ABORTED:
+        case DNS_TRANSACTION_DNSSEC_FAILED:
+        case DNS_TRANSACTION_NO_TRUST_ANCHOR:
+        case DNS_TRANSACTION_RR_TYPE_UNSUPPORTED:
+        case DNS_TRANSACTION_NETWORK_DOWN:
+                (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL);
+                break;
+
+        case DNS_TRANSACTION_NULL:
+        case DNS_TRANSACTION_PENDING:
+        case DNS_TRANSACTION_VALIDATING:
+        default:
+                assert_not_reached("Impossible state");
+        }
+
+        /* If there's a packet to write set, let's leave the stream around */
+        if (q->request_dns_stream && DNS_STREAM_QUEUED(q->request_dns_stream)) {
+
+                /* Detach the stream from our query (make it an orphan), but do not drop the reference to it. The
+                 * default completion action of the stream will drop the reference. */
+
+                dns_stub_detach_stream(q->request_dns_stream);
+                q->request_dns_stream = NULL;
+        }
+
+        dns_query_free(q);
+}
+
+static int dns_stub_stream_complete(DnsStream *s, int error) {
+        assert(s);
+
+        log_debug_errno(error, "DNS TCP connection terminated, destroying query: %m");
+
+        assert(s->query);
+        dns_query_free(s->query);
+
+        return 0;
+}
+
+static void dns_stub_process_query(Manager *m, DnsStream *s, DnsPacket *p) {
+        DnsQuery *q = NULL;
+        int r;
+
+        assert(m);
+        assert(p);
+        assert(p->protocol == DNS_PROTOCOL_DNS);
+
+        /* Takes ownership of the *s stream object */
+
+        if (in_addr_is_localhost(p->family, &p->sender) <= 0 ||
+            in_addr_is_localhost(p->family, &p->destination) <= 0) {
+                log_error("Got packet on unexpected IP range, refusing.");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
+                goto fail;
+        }
+
+        r = dns_packet_extract(p);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to extract resources from incoming packet, ignoring packet: %m");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_FORMERR);
+                goto fail;
+        }
+
+        if (!DNS_PACKET_VERSION_SUPPORTED(p)) {
+                log_debug("Got EDNS OPT field with unsupported version number.");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_BADVERS);
+                goto fail;
+        }
+
+        if (dns_type_is_obsolete(p->question->keys[0]->type)) {
+                log_debug("Got message with obsolete key type, refusing.");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP);
+                goto fail;
+        }
+
+        if (dns_type_is_zone_transer(p->question->keys[0]->type)) {
+                log_debug("Got request for zone transfer, refusing.");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP);
+                goto fail;
+        }
+
+        if (!DNS_PACKET_RD(p))  {
+                /* If the "rd" bit is off (i.e. recursion was not requested), then refuse operation */
+                log_debug("Got request with recursion disabled, refusing.");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_REFUSED);
+                goto fail;
+        }
+
+        if (DNS_PACKET_DO(p) && DNS_PACKET_CD(p)) {
+                log_debug("Got request with DNSSEC CD bit set, refusing.");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP);
+                goto fail;
+        }
+
+        r = dns_query_new(m, &q, p->question, p->question, 0, SD_RESOLVED_PROTOCOLS_ALL|SD_RESOLVED_NO_SEARCH|SD_RESOLVED_NO_CNAME);
+        if (r < 0) {
+                log_error_errno(r, "Failed to generate query object: %m");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
+                goto fail;
+        }
+
+        /* Request that the TTL is corrected by the cached time for this lookup, so that we return vaguely useful TTLs */
+        q->clamp_ttl = true;
+
+        q->request_dns_packet = dns_packet_ref(p);
+        q->request_dns_stream = dns_stream_ref(s); /* make sure the stream stays around until we can send a reply through it */
+        q->complete = dns_stub_query_complete;
+
+        if (s) {
+                s->on_packet = NULL;
+                s->complete = dns_stub_stream_complete;
+                s->query = q;
+        }
+
+        r = dns_query_go(q);
+        if (r < 0) {
+                log_error_errno(r, "Failed to start query: %m");
+                dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
+                goto fail;
+        }
+
+        log_info("Processing query...");
+        return;
+
+fail:
+        if (s && DNS_STREAM_QUEUED(s))
+                dns_stub_detach_stream(s);
+
+        dns_query_free(q);
+}
+
+static int on_dns_stub_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+        Manager *m = userdata;
+        int r;
+
+        r = manager_recv(m, fd, DNS_PROTOCOL_DNS, &p);
+        if (r <= 0)
+                return r;
+
+        if (dns_packet_validate_query(p) > 0) {
+                log_debug("Got DNS stub UDP query packet for id %u", DNS_PACKET_ID(p));
+
+                dns_stub_process_query(m, NULL, p);
+        } else
+                log_debug("Invalid DNS stub UDP packet, ignoring.");
+
+        return 0;
+}
+
+static int manager_dns_stub_udp_fd(Manager *m) {
+        static const int one = 1;
+        union sockaddr_union sa = {
+                .in.sin_family = AF_INET,
+                .in.sin_port = htobe16(53),
+                .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
+        };
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        if (m->dns_stub_udp_fd >= 0)
+                return m->dns_stub_udp_fd;
+
+        fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (fd < 0)
+                return -errno;
+
+        if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0)
+                return -errno;
+
+        if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0)
+                return -errno;
+
+        if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0)
+                return -errno;
+
+        /* Make sure no traffic from outside the local host can leak to onto this socket */
+        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0)
+                return -errno;
+
+        if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
+                return -errno;
+
+        r = sd_event_add_io(m->event, &m->dns_stub_udp_event_source, fd, EPOLLIN, on_dns_stub_packet, m);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_source_set_description(m->dns_stub_udp_event_source, "dns-stub-udp");
+        m->dns_stub_udp_fd = fd;
+        fd = -1;
+
+        return m->dns_stub_udp_fd;
+}
+
+static int on_dns_stub_stream_packet(DnsStream *s) {
+        assert(s);
+        assert(s->read_packet);
+
+        if (dns_packet_validate_query(s->read_packet) > 0) {
+                log_debug("Got DNS stub TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
+
+                dns_stub_process_query(s->manager, s, s->read_packet);
+        } else
+                log_debug("Invalid DNS stub TCP packet, ignoring.");
+
+        /* Drop the reference to the stream. Either a query was created and added its own reference to the stream now,
+         * or that didn't happen in which case we want to free the stream */
+        dns_stream_unref(s);
+
+        return 0;
+}
+
+static int on_dns_stub_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        DnsStream *stream;
+        Manager *m = userdata;
+        int cfd, r;
+
+        cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+        if (cfd < 0) {
+                if (errno == EAGAIN || errno == EINTR)
+                        return 0;
+
+                return -errno;
+        }
+
+        r = dns_stream_new(m, &stream, DNS_PROTOCOL_DNS, cfd);
+        if (r < 0) {
+                safe_close(cfd);
+                return r;
+        }
+
+        stream->on_packet = on_dns_stub_stream_packet;
+
+        /* We let the reference to the stream dangling here, it will either be dropped by the default "complete" action
+         * of the stream, or by our packet callback, or when the manager is shut down. */
+
+        return 0;
+}
+
+static int manager_dns_stub_tcp_fd(Manager *m) {
+        static const int one = 1;
+        union sockaddr_union sa = {
+                .in.sin_family = AF_INET,
+                .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
+                .in.sin_port = htobe16(53),
+        };
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        if (m->dns_stub_tcp_fd >= 0)
+                return m->dns_stub_tcp_fd;
+
+        fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (fd < 0)
+                return -errno;
+
+        if (setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof one) < 0)
+                return -errno;
+
+        if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0)
+                return -errno;
+
+        if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0)
+                return -errno;
+
+        if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0)
+                return -errno;
+
+        /* Make sure no traffic from outside the local host can leak to onto this socket */
+        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0)
+                return -errno;
+
+        if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
+                return -errno;
+
+        if (listen(fd, SOMAXCONN) < 0)
+                return -errno;
+
+        r = sd_event_add_io(m->event, &m->dns_stub_tcp_event_source, fd, EPOLLIN, on_dns_stub_stream, m);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_source_set_description(m->dns_stub_tcp_event_source, "dns-stub-tcp");
+        m->dns_stub_tcp_fd = fd;
+        fd = -1;
+
+        return m->dns_stub_tcp_fd;
+}
+
+int manager_dns_stub_start(Manager *m) {
+        const char *t = "UDP";
+        int r = 0;
+
+        assert(m);
+
+        if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP))
+                r = manager_dns_stub_udp_fd(m);
+
+        if (r >= 0 &&
+            IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_TCP)) {
+                t = "TCP";
+                r = manager_dns_stub_tcp_fd(m);
+        }
+
+        if (IN_SET(r, -EADDRINUSE, -EPERM)) {
+                if (r == -EADDRINUSE)
+                        log_warning_errno(r,
+                                          "Another process is already listening on %s socket 127.0.0.53:53.\n"
+                                          "Turning off local DNS stub support.", t);
+                else
+                        log_warning_errno(r,
+                                          "Failed to listen on %s socket 127.0.0.53:53: %m.\n"
+                                          "Turning off local DNS stub support.", t);
+                manager_dns_stub_stop(m);
+        } else if (r < 0)
+                return log_error_errno(r, "Failed to listen on %s socket 127.0.0.53:53: %m", t);
+
+        return 0;
+}
+
+void manager_dns_stub_stop(Manager *m) {
+        assert(m);
+
+        m->dns_stub_udp_event_source = sd_event_source_unref(m->dns_stub_udp_event_source);
+        m->dns_stub_tcp_event_source = sd_event_source_unref(m->dns_stub_tcp_event_source);
+
+        m->dns_stub_udp_fd = safe_close(m->dns_stub_udp_fd);
+        m->dns_stub_tcp_fd = safe_close(m->dns_stub_tcp_fd);
+}