[thirdparty/systemd.git] / src / resolve / resolved-dnstls-gnutls.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#if !ENABLE_DNS_OVER_TLS || !DNS_OVER_TLS_USE_GNUTLS
#error This source file requires DNS-over-TLS to be enabled and GnuTLS to be available.
#endif

#include <gnutls/socket.h>

#include "resolved-dns-stream.h"
#include "resolved-dnstls.h"

#define TLS_PROTOCOL_PRIORITY "NORMAL:-VERS-ALL:+VERS-TLS1.3:+VERS-TLS1.2"
DEFINE_TRIVIAL_CLEANUP_FUNC(gnutls_session_t, gnutls_deinit);

static ssize_t dnstls_stream_writev(gnutls_transport_ptr_t p, const giovec_t *iov, int iovcnt) {
        int r;

        assert(p);

        r = dns_stream_writev((DnsStream*) p, (const struct iovec*) iov, iovcnt, DNS_STREAM_WRITE_TLS_DATA);
        if (r < 0) {
                errno = -r;
                return -1;
        }

        return r;
}

int dnstls_stream_connect_tls(DnsStream *stream, DnsServer *server) {
        _cleanup_(gnutls_deinitp) gnutls_session_t gs;
        int r;

        assert(stream);
        assert(server);

        r = gnutls_init(&gs, GNUTLS_CLIENT | GNUTLS_ENABLE_FALSE_START | GNUTLS_NONBLOCK);
        if (r < 0)
                return r;

        /* As DNS-over-TLS is a recent protocol, older TLS versions can be disabled */
        r = gnutls_priority_set_direct(gs, TLS_PROTOCOL_PRIORITY, NULL);
        if (r < 0)
                return r;

        r = gnutls_credentials_set(gs, GNUTLS_CRD_CERTIFICATE, stream->manager->dnstls_data.cert_cred);
        if (r < 0)
                return r;

        if (server->dnstls_data.session_data.size > 0) {
                gnutls_session_set_data(gs, server->dnstls_data.session_data.data, server->dnstls_data.session_data.size);

                // Clear old session ticket
                gnutls_free(server->dnstls_data.session_data.data);
                server->dnstls_data.session_data.data = NULL;
                server->dnstls_data.session_data.size = 0;
        }

        if (server->manager->dns_over_tls_mode == DNS_OVER_TLS_YES) {
                stream->dnstls_data.validation.type = GNUTLS_DT_IP_ADDRESS;
                if (server->family == AF_INET) {
                        stream->dnstls_data.validation.data = (unsigned char*) &server->address.in.s_addr;
                        stream->dnstls_data.validation.size = 4;
                } else {
                        stream->dnstls_data.validation.data = server->address.in6.s6_addr;
                        stream->dnstls_data.validation.size = 16;
                }
                gnutls_session_set_verify_cert2(gs, &stream->dnstls_data.validation, 1, 0);
        }

        gnutls_handshake_set_timeout(gs, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

        gnutls_transport_set_ptr2(gs, (gnutls_transport_ptr_t) (long) stream->fd, stream);
        gnutls_transport_set_vec_push_function(gs, &dnstls_stream_writev);

        stream->encrypted = true;
        stream->dnstls_data.handshake = gnutls_handshake(gs);
        if (stream->dnstls_data.handshake < 0 && gnutls_error_is_fatal(stream->dnstls_data.handshake))
                return -ECONNREFUSED;

        stream->dnstls_data.session = TAKE_PTR(gs);

        return 0;
}

void dnstls_stream_free(DnsStream *stream) {
        assert(stream);
        assert(stream->encrypted);

        if (stream->dnstls_data.session)
                gnutls_deinit(stream->dnstls_data.session);
}

int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
        int r;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.session);

        if (stream->dnstls_data.shutdown) {
                r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
                if (r == GNUTLS_E_AGAIN) {
                        stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
                        return -EAGAIN;
                } else if (r < 0)
                        log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));

                stream->dnstls_events = 0;
                stream->dnstls_data.shutdown = false;
                dns_stream_unref(stream);
                return DNSTLS_STREAM_CLOSED;
        } else if (stream->dnstls_data.handshake < 0) {
                stream->dnstls_data.handshake = gnutls_handshake(stream->dnstls_data.session);
                if (stream->dnstls_data.handshake == GNUTLS_E_AGAIN) {
                        stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
                        return -EAGAIN;
                } else if (stream->dnstls_data.handshake < 0) {
                        log_debug("Failed to invoke gnutls_handshake: %s", gnutls_strerror(stream->dnstls_data.handshake));
                        if (gnutls_error_is_fatal(stream->dnstls_data.handshake))
                                return -ECONNREFUSED;
                }

                stream->dnstls_events = 0;
        }

        return 0;
}

int dnstls_stream_shutdown(DnsStream *stream, int error) {
        int r;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.session);

        /* Store TLS Ticket for faster successive TLS handshakes */
        if (stream->server && stream->server->dnstls_data.session_data.size == 0 && stream->dnstls_data.handshake == GNUTLS_E_SUCCESS)
                gnutls_session_get_data2(stream->dnstls_data.session, &stream->server->dnstls_data.session_data);

        if (IN_SET(error, ETIMEDOUT, 0)) {
                r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
                if (r == GNUTLS_E_AGAIN) {
                        if (!stream->dnstls_data.shutdown) {
                                stream->dnstls_data.shutdown = true;
                                dns_stream_ref(stream);
                                return -EAGAIN;
                        }
                } else if (r < 0)
                        log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
        }

        return 0;
}

ssize_t dnstls_stream_write(DnsStream *stream, const char *buf, size_t count) {
        ssize_t ss;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.session);
        assert(buf);

        ss = gnutls_record_send(stream->dnstls_data.session, buf, count);
        if (ss < 0)
                switch(ss) {
                case GNUTLS_E_INTERRUPTED:
                        return -EINTR;
                case GNUTLS_E_AGAIN:
                        return -EAGAIN;
                default:
                        return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
                                               "Failed to invoke gnutls_record_send: %s",
                                               gnutls_strerror(ss));
                }

        return ss;
}

ssize_t dnstls_stream_read(DnsStream *stream, void *buf, size_t count) {
        ssize_t ss;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.session);
        assert(buf);

        ss = gnutls_record_recv(stream->dnstls_data.session, buf, count);
        if (ss < 0)
                switch(ss) {
                case GNUTLS_E_INTERRUPTED:
                        return -EINTR;
                case GNUTLS_E_AGAIN:
                        return -EAGAIN;
                default:
                        return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
                                               "Failed to invoke gnutls_record_recv: %s",
                                               gnutls_strerror(ss));
                }

        return ss;
}

void dnstls_server_free(DnsServer *server) {
        assert(server);

        if (server->dnstls_data.session_data.data)
                gnutls_free(server->dnstls_data.session_data.data);
}

int dnstls_manager_init(Manager *manager) {
        int r;
        assert(manager);

        r = gnutls_certificate_allocate_credentials(&manager->dnstls_data.cert_cred);
        if (r < 0)
                return -ENOMEM;

        r = gnutls_certificate_set_x509_system_trust(manager->dnstls_data.cert_cred);
        if (r < 0)
                log_warning("Failed to load system trust store: %s", gnutls_strerror(r));

        return 0;
}

void dnstls_manager_free(Manager *manager) {
        assert(manager);

        if (manager->dnstls_data.cert_cred)
                gnutls_certificate_free_credentials(manager->dnstls_data.cert_cred);
}
Commit	Line	Data
6016fcb0 IT	1	/* SPDX-License-Identifier: LGPL-2.1+ */
6016fcb0 IT	2
096cbdce	3	#if !ENABLE_DNS_OVER_TLS \|\| !DNS_OVER_TLS_USE_GNUTLS
6016fcb0 IT	4	#error This source file requires DNS-over-TLS to be enabled and GnuTLS to be available.
	5	#endif
	6
6016fcb0 IT	7	#include <gnutls/socket.h>
6016fcb0 IT	8
72938b93 YW	9	#include "resolved-dns-stream.h"
	10	#include "resolved-dnstls.h"
	11
7f95bb22	12	#define TLS_PROTOCOL_PRIORITY "NORMAL:-VERS-ALL:+VERS-TLS1.3:+VERS-TLS1.2"
6016fcb0 IT	13	DEFINE_TRIVIAL_CLEANUP_FUNC(gnutls_session_t, gnutls_deinit);
	14
	15	static ssize_t dnstls_stream_writev(gnutls_transport_ptr_t p, const giovec_t *iov, int iovcnt) {
	16	int r;
	17
	18	assert(p);
	19
	20	r = dns_stream_writev((DnsStream) p, (const struct iovec) iov, iovcnt, DNS_STREAM_WRITE_TLS_DATA);
	21	if (r < 0) {
	22	errno = -r;
	23	return -1;
	24	}
	25
	26	return r;
	27	}
	28
	29	int dnstls_stream_connect_tls(DnsStream stream, DnsServer server) {
	30	_cleanup_(gnutls_deinitp) gnutls_session_t gs;
	31	int r;
	32
	33	assert(stream);
	34	assert(server);
	35
	36	r = gnutls_init(&gs, GNUTLS_CLIENT \| GNUTLS_ENABLE_FALSE_START \| GNUTLS_NONBLOCK);
	37	if (r < 0)
	38	return r;
	39
	40	/* As DNS-over-TLS is a recent protocol, older TLS versions can be disabled */
7f95bb22	41	r = gnutls_priority_set_direct(gs, TLS_PROTOCOL_PRIORITY, NULL);
6016fcb0 IT	42	if (r < 0)
	43	return r;
	44
e22c5b20	45	r = gnutls_credentials_set(gs, GNUTLS_CRD_CERTIFICATE, stream->manager->dnstls_data.cert_cred);
6016fcb0 IT	46	if (r < 0)
	47	return r;
	48
	49	if (server->dnstls_data.session_data.size > 0) {
	50	gnutls_session_set_data(gs, server->dnstls_data.session_data.data, server->dnstls_data.session_data.size);
	51
	52	// Clear old session ticket
	53	gnutls_free(server->dnstls_data.session_data.data);
	54	server->dnstls_data.session_data.data = NULL;
	55	server->dnstls_data.session_data.size = 0;
	56	}
	57
7f2f4fac IT	58	if (server->manager->dns_over_tls_mode == DNS_OVER_TLS_YES) {
	59	stream->dnstls_data.validation.type = GNUTLS_DT_IP_ADDRESS;
	60	if (server->family == AF_INET) {
	61	stream->dnstls_data.validation.data = (unsigned char*) &server->address.in.s_addr;
	62	stream->dnstls_data.validation.size = 4;
	63	} else {
	64	stream->dnstls_data.validation.data = server->address.in6.s6_addr;
	65	stream->dnstls_data.validation.size = 16;
	66	}
	67	gnutls_session_set_verify_cert2(gs, &stream->dnstls_data.validation, 1, 0);
	68	}
4310bfc2	69
6016fcb0 IT	70	gnutls_handshake_set_timeout(gs, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
	71
	72	gnutls_transport_set_ptr2(gs, (gnutls_transport_ptr_t) (long) stream->fd, stream);
	73	gnutls_transport_set_vec_push_function(gs, &dnstls_stream_writev);
	74
	75	stream->encrypted = true;
	76	stream->dnstls_data.handshake = gnutls_handshake(gs);
	77	if (stream->dnstls_data.handshake < 0 && gnutls_error_is_fatal(stream->dnstls_data.handshake))
	78	return -ECONNREFUSED;
	79
	80	stream->dnstls_data.session = TAKE_PTR(gs);
	81
	82	return 0;
	83	}
	84
	85	void dnstls_stream_free(DnsStream *stream) {
	86	assert(stream);
	87	assert(stream->encrypted);
	88
	89	if (stream->dnstls_data.session)
	90	gnutls_deinit(stream->dnstls_data.session);
	91	}
	92
04c4d919	93	int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
6016fcb0 IT	94	int r;
	95
	96	assert(stream);
	97	assert(stream->encrypted);
	98	assert(stream->dnstls_data.session);
	99
	100	if (stream->dnstls_data.shutdown) {
	101	r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
ba6aaf57 IT	102	if (r == GNUTLS_E_AGAIN) {
ba6aaf57 IT	103	stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
6016fcb0	104	return -EAGAIN;
ba6aaf57	105	} else if (r < 0)
6016fcb0 IT	106	log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
6016fcb0 IT	107
ba6aaf57	108	stream->dnstls_events = 0;
6016fcb0 IT	109	stream->dnstls_data.shutdown = false;
	110	dns_stream_unref(stream);
	111	return DNSTLS_STREAM_CLOSED;
	112	} else if (stream->dnstls_data.handshake < 0) {
	113	stream->dnstls_data.handshake = gnutls_handshake(stream->dnstls_data.session);
ba6aaf57 IT	114	if (stream->dnstls_data.handshake == GNUTLS_E_AGAIN) {
ba6aaf57 IT	115	stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
6016fcb0	116	return -EAGAIN;
ba6aaf57	117	} else if (stream->dnstls_data.handshake < 0) {
6016fcb0 IT	118	log_debug("Failed to invoke gnutls_handshake: %s", gnutls_strerror(stream->dnstls_data.handshake));
	119	if (gnutls_error_is_fatal(stream->dnstls_data.handshake))
	120	return -ECONNREFUSED;
	121	}
ba6aaf57 IT	122
ba6aaf57 IT	123	stream->dnstls_events = 0;
6016fcb0 IT	124	}
	125
	126	return 0;
	127	}
	128
	129	int dnstls_stream_shutdown(DnsStream *stream, int error) {
	130	int r;
	131
	132	assert(stream);
	133	assert(stream->encrypted);
	134	assert(stream->dnstls_data.session);
	135
5238e957	136	/* Store TLS Ticket for faster successive TLS handshakes */
6016fcb0 IT	137	if (stream->server && stream->server->dnstls_data.session_data.size == 0 && stream->dnstls_data.handshake == GNUTLS_E_SUCCESS)
	138	gnutls_session_get_data2(stream->dnstls_data.session, &stream->server->dnstls_data.session_data);
	139
	140	if (IN_SET(error, ETIMEDOUT, 0)) {
	141	r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
	142	if (r == GNUTLS_E_AGAIN) {
	143	if (!stream->dnstls_data.shutdown) {
	144	stream->dnstls_data.shutdown = true;
	145	dns_stream_ref(stream);
	146	return -EAGAIN;
	147	}
	148	} else if (r < 0)
	149	log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
	150	}
	151
	152	return 0;
	153	}
	154
	155	ssize_t dnstls_stream_write(DnsStream stream, const char buf, size_t count) {
	156	ssize_t ss;
	157
	158	assert(stream);
	159	assert(stream->encrypted);
	160	assert(stream->dnstls_data.session);
	161	assert(buf);
	162
	163	ss = gnutls_record_send(stream->dnstls_data.session, buf, count);
	164	if (ss < 0)
	165	switch(ss) {
	166	case GNUTLS_E_INTERRUPTED:
	167	return -EINTR;
	168	case GNUTLS_E_AGAIN:
	169	return -EAGAIN;
	170	default:
baaa35ad ZJS	171	return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
	172	"Failed to invoke gnutls_record_send: %s",
	173	gnutls_strerror(ss));
6016fcb0 IT	174	}
	175
	176	return ss;
	177	}
	178
	179	ssize_t dnstls_stream_read(DnsStream stream, void buf, size_t count) {
	180	ssize_t ss;
	181
	182	assert(stream);
	183	assert(stream->encrypted);
	184	assert(stream->dnstls_data.session);
	185	assert(buf);
	186
	187	ss = gnutls_record_recv(stream->dnstls_data.session, buf, count);
	188	if (ss < 0)
	189	switch(ss) {
	190	case GNUTLS_E_INTERRUPTED:
	191	return -EINTR;
	192	case GNUTLS_E_AGAIN:
	193	return -EAGAIN;
	194	default:
baaa35ad ZJS	195	return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
	196	"Failed to invoke gnutls_record_recv: %s",
	197	gnutls_strerror(ss));
6016fcb0 IT	198	}
	199
	200	return ss;
	201	}
	202
e22c5b20	203	void dnstls_server_free(DnsServer *server) {
6016fcb0 IT	204	assert(server);
6016fcb0 IT	205
e22c5b20 IT	206	if (server->dnstls_data.session_data.data)
e22c5b20 IT	207	gnutls_free(server->dnstls_data.session_data.data);
6016fcb0 IT	208	}
6016fcb0 IT	209
71a681ae	210	int dnstls_manager_init(Manager *manager) {
e22c5b20 IT	211	int r;
e22c5b20 IT	212	assert(manager);
6016fcb0	213
71a681ae	214	r = gnutls_certificate_allocate_credentials(&manager->dnstls_data.cert_cred);
e22c5b20	215	if (r < 0)
71a681ae IT	216	return -ENOMEM;
71a681ae IT	217
4310bfc2 IT	218	r = gnutls_certificate_set_x509_system_trust(manager->dnstls_data.cert_cred);
	219	if (r < 0)
	220	log_warning("Failed to load system trust store: %s", gnutls_strerror(r));
	221
71a681ae	222	return 0;
e22c5b20	223	}
6016fcb0	224
e22c5b20 IT	225	void dnstls_manager_free(Manager *manager) {
	226	assert(manager);
	227
	228	if (manager->dnstls_data.cert_cred)
	229	gnutls_certificate_free_credentials(manager->dnstls_data.cert_cred);
6016fcb0	230	}