[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);
        }

        if (server->server_name) {
                r = gnutls_server_name_set(gs, GNUTLS_NAME_DNS, server->server_name, strlen(server->server_name));
                if (r < 0)
                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to set server name: %s", gnutls_strerror(r));
        }

        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
2e22a54f GL	70	if (server->server_name) {
	71	r = gnutls_server_name_set(gs, GNUTLS_NAME_DNS, server->server_name, strlen(server->server_name));
	72	if (r < 0)
	73	return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to set server name: %s", gnutls_strerror(r));
	74	}
	75
6016fcb0 IT	76	gnutls_handshake_set_timeout(gs, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
	77
	78	gnutls_transport_set_ptr2(gs, (gnutls_transport_ptr_t) (long) stream->fd, stream);
	79	gnutls_transport_set_vec_push_function(gs, &dnstls_stream_writev);
	80
	81	stream->encrypted = true;
	82	stream->dnstls_data.handshake = gnutls_handshake(gs);
	83	if (stream->dnstls_data.handshake < 0 && gnutls_error_is_fatal(stream->dnstls_data.handshake))
	84	return -ECONNREFUSED;
	85
	86	stream->dnstls_data.session = TAKE_PTR(gs);
	87
	88	return 0;
	89	}
	90
	91	void dnstls_stream_free(DnsStream *stream) {
	92	assert(stream);
	93	assert(stream->encrypted);
	94
	95	if (stream->dnstls_data.session)
	96	gnutls_deinit(stream->dnstls_data.session);
	97	}
	98
04c4d919	99	int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
6016fcb0 IT	100	int r;
	101
	102	assert(stream);
	103	assert(stream->encrypted);
	104	assert(stream->dnstls_data.session);
	105
	106	if (stream->dnstls_data.shutdown) {
	107	r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
ba6aaf57 IT	108	if (r == GNUTLS_E_AGAIN) {
ba6aaf57 IT	109	stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
6016fcb0	110	return -EAGAIN;
ba6aaf57	111	} else if (r < 0)
6016fcb0 IT	112	log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
6016fcb0 IT	113
ba6aaf57	114	stream->dnstls_events = 0;
6016fcb0 IT	115	stream->dnstls_data.shutdown = false;
	116	dns_stream_unref(stream);
	117	return DNSTLS_STREAM_CLOSED;
	118	} else if (stream->dnstls_data.handshake < 0) {
	119	stream->dnstls_data.handshake = gnutls_handshake(stream->dnstls_data.session);
ba6aaf57 IT	120	if (stream->dnstls_data.handshake == GNUTLS_E_AGAIN) {
ba6aaf57 IT	121	stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
6016fcb0	122	return -EAGAIN;
ba6aaf57	123	} else if (stream->dnstls_data.handshake < 0) {
6016fcb0 IT	124	log_debug("Failed to invoke gnutls_handshake: %s", gnutls_strerror(stream->dnstls_data.handshake));
	125	if (gnutls_error_is_fatal(stream->dnstls_data.handshake))
	126	return -ECONNREFUSED;
	127	}
ba6aaf57 IT	128
ba6aaf57 IT	129	stream->dnstls_events = 0;
6016fcb0 IT	130	}
	131
	132	return 0;
	133	}
	134
	135	int dnstls_stream_shutdown(DnsStream *stream, int error) {
	136	int r;
	137
	138	assert(stream);
	139	assert(stream->encrypted);
	140	assert(stream->dnstls_data.session);
	141
5238e957	142	/* Store TLS Ticket for faster successive TLS handshakes */
6016fcb0 IT	143	if (stream->server && stream->server->dnstls_data.session_data.size == 0 && stream->dnstls_data.handshake == GNUTLS_E_SUCCESS)
	144	gnutls_session_get_data2(stream->dnstls_data.session, &stream->server->dnstls_data.session_data);
	145
	146	if (IN_SET(error, ETIMEDOUT, 0)) {
	147	r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
	148	if (r == GNUTLS_E_AGAIN) {
	149	if (!stream->dnstls_data.shutdown) {
	150	stream->dnstls_data.shutdown = true;
	151	dns_stream_ref(stream);
	152	return -EAGAIN;
	153	}
	154	} else if (r < 0)
	155	log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
	156	}
	157
	158	return 0;
	159	}
	160
	161	ssize_t dnstls_stream_write(DnsStream stream, const char buf, size_t count) {
	162	ssize_t ss;
	163
	164	assert(stream);
	165	assert(stream->encrypted);
	166	assert(stream->dnstls_data.session);
	167	assert(buf);
	168
	169	ss = gnutls_record_send(stream->dnstls_data.session, buf, count);
	170	if (ss < 0)
	171	switch(ss) {
	172	case GNUTLS_E_INTERRUPTED:
	173	return -EINTR;
	174	case GNUTLS_E_AGAIN:
	175	return -EAGAIN;
	176	default:
baaa35ad ZJS	177	return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
	178	"Failed to invoke gnutls_record_send: %s",
	179	gnutls_strerror(ss));
6016fcb0 IT	180	}
	181
	182	return ss;
	183	}
	184
	185	ssize_t dnstls_stream_read(DnsStream stream, void buf, size_t count) {
	186	ssize_t ss;
	187
	188	assert(stream);
	189	assert(stream->encrypted);
	190	assert(stream->dnstls_data.session);
	191	assert(buf);
	192
	193	ss = gnutls_record_recv(stream->dnstls_data.session, buf, count);
	194	if (ss < 0)
	195	switch(ss) {
	196	case GNUTLS_E_INTERRUPTED:
	197	return -EINTR;
	198	case GNUTLS_E_AGAIN:
	199	return -EAGAIN;
	200	default:
baaa35ad ZJS	201	return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
	202	"Failed to invoke gnutls_record_recv: %s",
	203	gnutls_strerror(ss));
6016fcb0 IT	204	}
	205
	206	return ss;
	207	}
	208
e22c5b20	209	void dnstls_server_free(DnsServer *server) {
6016fcb0 IT	210	assert(server);
6016fcb0 IT	211
e22c5b20 IT	212	if (server->dnstls_data.session_data.data)
e22c5b20 IT	213	gnutls_free(server->dnstls_data.session_data.data);
6016fcb0 IT	214	}
6016fcb0 IT	215
71a681ae	216	int dnstls_manager_init(Manager *manager) {
e22c5b20 IT	217	int r;
e22c5b20 IT	218	assert(manager);
6016fcb0	219
71a681ae	220	r = gnutls_certificate_allocate_credentials(&manager->dnstls_data.cert_cred);
e22c5b20	221	if (r < 0)
71a681ae IT	222	return -ENOMEM;
71a681ae IT	223
4310bfc2 IT	224	r = gnutls_certificate_set_x509_system_trust(manager->dnstls_data.cert_cred);
	225	if (r < 0)
	226	log_warning("Failed to load system trust store: %s", gnutls_strerror(r));
	227
71a681ae	228	return 0;
e22c5b20	229	}
6016fcb0	230
e22c5b20 IT	231	void dnstls_manager_free(Manager *manager) {
	232	assert(manager);
	233
	234	if (manager->dnstls_data.cert_cred)
	235	gnutls_certificate_free_credentials(manager->dnstls_data.cert_cred);
6016fcb0	236	}