Adding upstream version 252.22.upstream/252.22

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 471 insertions, 0 deletions

diff --git a/src/resolve/resolved-llmnr.c b/src/resolve/resolved-llmnr.c
new file mode 100644
index 0000000..9f5a0b5
--- /dev/null
+++ b/src/resolve/resolved-llmnr.c
@@ -0,0 +1,471 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <resolv.h>
+
+#include "errno-util.h"
+#include "fd-util.h"
+#include "resolved-llmnr.h"
+#include "resolved-manager.h"
+
+void manager_llmnr_stop(Manager *m) {
+        assert(m);
+
+        m->llmnr_ipv4_udp_event_source = sd_event_source_disable_unref(m->llmnr_ipv4_udp_event_source);
+        m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
+
+        m->llmnr_ipv6_udp_event_source = sd_event_source_disable_unref(m->llmnr_ipv6_udp_event_source);
+        m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
+
+        m->llmnr_ipv4_tcp_event_source = sd_event_source_disable_unref(m->llmnr_ipv4_tcp_event_source);
+        m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
+
+        m->llmnr_ipv6_tcp_event_source = sd_event_source_disable_unref(m->llmnr_ipv6_tcp_event_source);
+        m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
+}
+
+int manager_llmnr_start(Manager *m) {
+        int r;
+
+        assert(m);
+
+        if (m->llmnr_support == RESOLVE_SUPPORT_NO)
+                return 0;
+
+        r = manager_llmnr_ipv4_udp_fd(m);
+        if (r == -EADDRINUSE)
+                goto eaddrinuse;
+        if (r < 0)
+                return r;
+
+        r = manager_llmnr_ipv4_tcp_fd(m);
+        if (r == -EADDRINUSE)
+                goto eaddrinuse;
+        if (r < 0)
+                return r;
+
+        if (socket_ipv6_is_enabled()) {
+                r = manager_llmnr_ipv6_udp_fd(m);
+                if (r == -EADDRINUSE)
+                        goto eaddrinuse;
+                if (r < 0)
+                        return r;
+
+                r = manager_llmnr_ipv6_tcp_fd(m);
+                if (r == -EADDRINUSE)
+                        goto eaddrinuse;
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+
+eaddrinuse:
+        log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
+        m->llmnr_support = RESOLVE_SUPPORT_NO;
+        manager_llmnr_stop(m);
+
+        return 0;
+}
+
+static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+        DnsTransaction *t = NULL;
+        Manager *m = ASSERT_PTR(userdata);
+        DnsScope *scope;
+        int r;
+
+        assert(s);
+        assert(fd >= 0);
+
+        r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
+        if (r <= 0)
+                return r;
+
+        if (manager_packet_from_local_address(m, p))
+                return 0;
+
+        scope = manager_find_scope(m, p);
+        if (!scope) {
+                log_debug("Got LLMNR UDP packet on unknown scope. Ignoring.");
+                return 0;
+        }
+
+        if (dns_packet_validate_reply(p) > 0) {
+                log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
+
+                dns_scope_check_conflicts(scope, p);
+
+                t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
+                if (t)
+                        dns_transaction_process_reply(t, p, false);
+
+        } else if (dns_packet_validate_query(p) > 0)  {
+                log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
+
+                dns_scope_process_query(scope, NULL, p);
+        } else
+                log_debug("Invalid LLMNR UDP packet, ignoring.");
+
+        return 0;
+}
+
+static int set_llmnr_common_socket_options(int fd, int family) {
+        int r;
+
+        r = socket_set_recvpktinfo(fd, family, true);
+        if (r < 0)
+                return r;
+
+        r = socket_set_recvttl(fd, family, true);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int set_llmnr_common_udp_socket_options(int fd, int family) {
+        int r;
+
+        /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
+        r = socket_set_ttl(fd, family, 255);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int manager_llmnr_ipv4_udp_fd(Manager *m) {
+        union sockaddr_union sa = {
+                .in.sin_family = AF_INET,
+                .in.sin_port = htobe16(LLMNR_PORT),
+        };
+        _cleanup_close_ int s = -1;
+        int r;
+
+        assert(m);
+
+        if (m->llmnr_ipv4_udp_fd >= 0)
+                return m->llmnr_ipv4_udp_fd;
+
+        s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (s < 0)
+                return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
+
+        r = set_llmnr_common_socket_options(s, AF_INET);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set common socket options: %m");
+
+        r = set_llmnr_common_udp_socket_options(s, AF_INET);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set common UDP socket options: %m");
+
+        r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_TTL, 255);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
+
+        r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_LOOP, true);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
+
+        /* Disable Don't-Fragment bit in the IP header */
+        r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
+
+        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
+        r = bind(s, &sa.sa, sizeof(sa.in));
+        if (r < 0) {
+                if (errno != EADDRINUSE)
+                        return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
+
+                log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
+
+                /* try again with SO_REUSEADDR */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
+
+                r = bind(s, &sa.sa, sizeof(sa.in));
+                if (r < 0)
+                        return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
+        } else {
+                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
+        }
+
+        r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, s, EPOLLIN, on_llmnr_packet, m);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to create event source: %m");
+
+        (void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
+
+        return m->llmnr_ipv4_udp_fd = TAKE_FD(s);
+}
+
+int manager_llmnr_ipv6_udp_fd(Manager *m) {
+        union sockaddr_union sa = {
+                .in6.sin6_family = AF_INET6,
+                .in6.sin6_port = htobe16(LLMNR_PORT),
+        };
+        _cleanup_close_ int s = -1;
+        int r;
+
+        assert(m);
+
+        if (m->llmnr_ipv6_udp_fd >= 0)
+                return m->llmnr_ipv6_udp_fd;
+
+        s = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (s < 0)
+                return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
+
+        r = set_llmnr_common_socket_options(s, AF_INET6);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set common socket options: %m");
+
+        r = set_llmnr_common_udp_socket_options(s, AF_INET6);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set common UDP socket options: %m");
+
+        /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
+        r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, 255);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
+
+        r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, true);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
+
+        r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
+
+        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
+        r = bind(s, &sa.sa, sizeof(sa.in6));
+        if (r < 0) {
+                if (errno != EADDRINUSE)
+                        return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
+
+                log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
+
+                /* try again with SO_REUSEADDR */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
+
+                r = bind(s, &sa.sa, sizeof(sa.in6));
+                if (r < 0)
+                        return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
+        } else {
+                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
+        }
+
+        r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, s, EPOLLIN, on_llmnr_packet, m);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to create event source: %m");
+
+        (void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
+
+        return m->llmnr_ipv6_udp_fd = TAKE_FD(s);
+}
+
+static int on_llmnr_stream_packet(DnsStream *s, DnsPacket *p) {
+        DnsScope *scope;
+
+        assert(s);
+        assert(s->manager);
+        assert(p);
+
+        scope = manager_find_scope(s->manager, p);
+        if (!scope)
+                log_debug("Got LLMNR TCP packet on unknown scope. Ignoring.");
+        else if (dns_packet_validate_query(p) > 0) {
+                log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(p));
+
+                dns_scope_process_query(scope, s, p);
+        } else
+                log_debug("Invalid LLMNR TCP packet, ignoring.");
+
+        return 0;
+}
+
+static int on_llmnr_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_IS_ACCEPT_AGAIN(errno))
+                        return 0;
+
+                return -errno;
+        }
+
+        /* We don't configure a "complete" handler here, we rely on the default handler, thus freeing it */
+        r = dns_stream_new(m, &stream, DNS_STREAM_LLMNR_RECV, DNS_PROTOCOL_LLMNR, cfd, NULL,
+                           on_llmnr_stream_packet, NULL, DNS_STREAM_DEFAULT_TIMEOUT_USEC);
+        if (r < 0) {
+                safe_close(cfd);
+                return r;
+        }
+
+        return 0;
+}
+
+static int set_llmnr_common_tcp_socket_options(int fd, int family) {
+        int r;
+
+        /* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
+        r = socket_set_ttl(fd, family, 1);
+        if (r < 0)
+                return r;
+
+        r = setsockopt_int(fd, IPPROTO_TCP, TCP_FASTOPEN, 5); /* Everybody appears to pick qlen=5, let's do the same here. */
+        if (r < 0)
+                log_debug_errno(r, "Failed to enable TCP_FASTOPEN on TCP listening socket, ignoring: %m");
+
+        r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true);
+        if (r < 0)
+                log_debug_errno(r, "Failed to enable TCP_NODELAY mode, ignoring: %m");
+
+        return 0;
+}
+
+int manager_llmnr_ipv4_tcp_fd(Manager *m) {
+        union sockaddr_union sa = {
+                .in.sin_family = AF_INET,
+                .in.sin_port = htobe16(LLMNR_PORT),
+        };
+        _cleanup_close_ int s = -1;
+        int r;
+
+        assert(m);
+
+        if (m->llmnr_ipv4_tcp_fd >= 0)
+                return m->llmnr_ipv4_tcp_fd;
+
+        s = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (s < 0)
+                return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
+
+        r = set_llmnr_common_socket_options(s, AF_INET);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set common socket options: %m");
+
+        r = set_llmnr_common_tcp_socket_options(s, AF_INET);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set common TCP socket options: %m");
+
+        /* Disable Don't-Fragment bit in the IP header */
+        r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
+
+        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
+        r = bind(s, &sa.sa, sizeof(sa.in));
+        if (r < 0) {
+                if (errno != EADDRINUSE)
+                        return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
+
+                log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
+
+                /* try again with SO_REUSEADDR */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
+
+                r = bind(s, &sa.sa, sizeof(sa.in));
+                if (r < 0)
+                        return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
+        } else {
+                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
+        }
+
+        r = listen(s, SOMAXCONN_DELUXE);
+        if (r < 0)
+                return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
+
+        r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, s, EPOLLIN, on_llmnr_stream, m);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to create event source: %m");
+
+        (void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
+
+        return m->llmnr_ipv4_tcp_fd = TAKE_FD(s);
+}
+
+int manager_llmnr_ipv6_tcp_fd(Manager *m) {
+        union sockaddr_union sa = {
+                .in6.sin6_family = AF_INET6,
+                .in6.sin6_port = htobe16(LLMNR_PORT),
+        };
+        _cleanup_close_ int s = -1;
+        int r;
+
+        assert(m);
+
+        if (m->llmnr_ipv6_tcp_fd >= 0)
+                return m->llmnr_ipv6_tcp_fd;
+
+        s = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (s < 0)
+                return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
+
+        r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
+
+        r = set_llmnr_common_socket_options(s, AF_INET6);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set common socket options: %m");
+
+        r = set_llmnr_common_tcp_socket_options(s, AF_INET6);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set common TCP socket options: %m");
+
+        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
+        r = bind(s, &sa.sa, sizeof(sa.in6));
+        if (r < 0) {
+                if (errno != EADDRINUSE)
+                        return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
+
+                log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
+
+                /* try again with SO_REUSEADDR */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
+
+                r = bind(s, &sa.sa, sizeof(sa.in6));
+                if (r < 0)
+                        return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
+        } else {
+                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
+                r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+                if (r < 0)
+                        return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
+        }
+
+        r = listen(s, SOMAXCONN_DELUXE);
+        if (r < 0)
+                return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
+
+        r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, s, EPOLLIN, on_llmnr_stream, m);
+        if (r < 0)
+                return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to create event source: %m");
+
+        (void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
+
+        return m->llmnr_ipv6_tcp_fd = TAKE_FD(s);
+}