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

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#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"
#include "resolved-manager.h"

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

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 = NULL;
        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) {
                if (server->server_name)
                        gnutls_session_set_verify_cert(gs, server->server_name, 0);
                else {
                        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
db9ecf05	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
6016fcb0	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"
72938b93 YW	10	#include "resolved-dnstls.h"
be28f72d	11	#include "resolved-manager.h"
72938b93	12
7f95bb22	13	#define TLS_PROTOCOL_PRIORITY "NORMAL:-VERS-ALL:+VERS-TLS1.3:+VERS-TLS1.2"
fd421c4a	14	DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(gnutls_session_t, gnutls_deinit, NULL);
6016fcb0 IT	15
	16	static ssize_t dnstls_stream_writev(gnutls_transport_ptr_t p, const giovec_t *iov, int iovcnt) {
	17	int r;
	18
	19	assert(p);
	20
	21	r = dns_stream_writev((DnsStream) p, (const struct iovec) iov, iovcnt, DNS_STREAM_WRITE_TLS_DATA);
	22	if (r < 0) {
	23	errno = -r;
	24	return -1;
	25	}
	26
	27	return r;
	28	}
	29
	30	int dnstls_stream_connect_tls(DnsStream stream, DnsServer server) {
b9c54c46	31	_cleanup_(gnutls_deinitp) gnutls_session_t gs = NULL;
6016fcb0 IT	32	int r;
	33
	34	assert(stream);
	35	assert(server);
	36
	37	r = gnutls_init(&gs, GNUTLS_CLIENT \| GNUTLS_ENABLE_FALSE_START \| GNUTLS_NONBLOCK);
	38	if (r < 0)
	39	return r;
	40
	41	/* As DNS-over-TLS is a recent protocol, older TLS versions can be disabled */
7f95bb22	42	r = gnutls_priority_set_direct(gs, TLS_PROTOCOL_PRIORITY, NULL);
6016fcb0 IT	43	if (r < 0)
	44	return r;
	45
e22c5b20	46	r = gnutls_credentials_set(gs, GNUTLS_CRD_CERTIFICATE, stream->manager->dnstls_data.cert_cred);
6016fcb0 IT	47	if (r < 0)
	48	return r;
	49
	50	if (server->dnstls_data.session_data.size > 0) {
	51	gnutls_session_set_data(gs, server->dnstls_data.session_data.data, server->dnstls_data.session_data.size);
	52
	53	// Clear old session ticket
	54	gnutls_free(server->dnstls_data.session_data.data);
	55	server->dnstls_data.session_data.data = NULL;
	56	server->dnstls_data.session_data.size = 0;
	57	}
	58
7f2f4fac	59	if (server->manager->dns_over_tls_mode == DNS_OVER_TLS_YES) {
eec394f1 JT	60	if (server->server_name)
	61	gnutls_session_set_verify_cert(gs, server->server_name, 0);
	62	else {
	63	stream->dnstls_data.validation.type = GNUTLS_DT_IP_ADDRESS;
	64	if (server->family == AF_INET) {
	65	stream->dnstls_data.validation.data = (unsigned char*) &server->address.in.s_addr;
	66	stream->dnstls_data.validation.size = 4;
	67	} else {
	68	stream->dnstls_data.validation.data = server->address.in6.s6_addr;
	69	stream->dnstls_data.validation.size = 16;
	70	}
	71	gnutls_session_set_verify_cert2(gs, &stream->dnstls_data.validation, 1, 0);
7f2f4fac	72	}
7f2f4fac	73	}
4310bfc2	74
2e22a54f GL	75	if (server->server_name) {
	76	r = gnutls_server_name_set(gs, GNUTLS_NAME_DNS, server->server_name, strlen(server->server_name));
	77	if (r < 0)
	78	return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to set server name: %s", gnutls_strerror(r));
	79	}
	80
6016fcb0 IT	81	gnutls_handshake_set_timeout(gs, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
	82
	83	gnutls_transport_set_ptr2(gs, (gnutls_transport_ptr_t) (long) stream->fd, stream);
	84	gnutls_transport_set_vec_push_function(gs, &dnstls_stream_writev);
	85
	86	stream->encrypted = true;
	87	stream->dnstls_data.handshake = gnutls_handshake(gs);
	88	if (stream->dnstls_data.handshake < 0 && gnutls_error_is_fatal(stream->dnstls_data.handshake))
	89	return -ECONNREFUSED;
	90
	91	stream->dnstls_data.session = TAKE_PTR(gs);
	92
	93	return 0;
	94	}
	95
	96	void dnstls_stream_free(DnsStream *stream) {
	97	assert(stream);
	98	assert(stream->encrypted);
	99
	100	if (stream->dnstls_data.session)
	101	gnutls_deinit(stream->dnstls_data.session);
	102	}
	103
04c4d919	104	int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
6016fcb0 IT	105	int r;
	106
	107	assert(stream);
	108	assert(stream->encrypted);
	109	assert(stream->dnstls_data.session);
	110
	111	if (stream->dnstls_data.shutdown) {
	112	r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
ba6aaf57 IT	113	if (r == GNUTLS_E_AGAIN) {
ba6aaf57 IT	114	stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
6016fcb0	115	return -EAGAIN;
ba6aaf57	116	} else if (r < 0)
6016fcb0 IT	117	log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
6016fcb0 IT	118
ba6aaf57	119	stream->dnstls_events = 0;
6016fcb0 IT	120	stream->dnstls_data.shutdown = false;
	121	dns_stream_unref(stream);
	122	return DNSTLS_STREAM_CLOSED;
	123	} else if (stream->dnstls_data.handshake < 0) {
	124	stream->dnstls_data.handshake = gnutls_handshake(stream->dnstls_data.session);
ba6aaf57 IT	125	if (stream->dnstls_data.handshake == GNUTLS_E_AGAIN) {
ba6aaf57 IT	126	stream->dnstls_events = gnutls_record_get_direction(stream->dnstls_data.session) == 1 ? EPOLLOUT : EPOLLIN;
6016fcb0	127	return -EAGAIN;
ba6aaf57	128	} else if (stream->dnstls_data.handshake < 0) {
6016fcb0 IT	129	log_debug("Failed to invoke gnutls_handshake: %s", gnutls_strerror(stream->dnstls_data.handshake));
	130	if (gnutls_error_is_fatal(stream->dnstls_data.handshake))
	131	return -ECONNREFUSED;
	132	}
ba6aaf57 IT	133
ba6aaf57 IT	134	stream->dnstls_events = 0;
6016fcb0 IT	135	}
	136
	137	return 0;
	138	}
	139
	140	int dnstls_stream_shutdown(DnsStream *stream, int error) {
	141	int r;
	142
	143	assert(stream);
	144	assert(stream->encrypted);
	145	assert(stream->dnstls_data.session);
	146
5238e957	147	/* Store TLS Ticket for faster successive TLS handshakes */
6016fcb0 IT	148	if (stream->server && stream->server->dnstls_data.session_data.size == 0 && stream->dnstls_data.handshake == GNUTLS_E_SUCCESS)
	149	gnutls_session_get_data2(stream->dnstls_data.session, &stream->server->dnstls_data.session_data);
	150
	151	if (IN_SET(error, ETIMEDOUT, 0)) {
	152	r = gnutls_bye(stream->dnstls_data.session, GNUTLS_SHUT_RDWR);
	153	if (r == GNUTLS_E_AGAIN) {
	154	if (!stream->dnstls_data.shutdown) {
	155	stream->dnstls_data.shutdown = true;
	156	dns_stream_ref(stream);
	157	return -EAGAIN;
	158	}
	159	} else if (r < 0)
	160	log_debug("Failed to invoke gnutls_bye: %s", gnutls_strerror(r));
	161	}
	162
	163	return 0;
	164	}
	165
	166	ssize_t dnstls_stream_write(DnsStream stream, const char buf, size_t count) {
	167	ssize_t ss;
	168
	169	assert(stream);
	170	assert(stream->encrypted);
	171	assert(stream->dnstls_data.session);
	172	assert(buf);
	173
	174	ss = gnutls_record_send(stream->dnstls_data.session, buf, count);
	175	if (ss < 0)
	176	switch(ss) {
	177	case GNUTLS_E_INTERRUPTED:
	178	return -EINTR;
	179	case GNUTLS_E_AGAIN:
	180	return -EAGAIN;
	181	default:
baaa35ad ZJS	182	return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
	183	"Failed to invoke gnutls_record_send: %s",
	184	gnutls_strerror(ss));
6016fcb0 IT	185	}
	186
	187	return ss;
	188	}
	189
	190	ssize_t dnstls_stream_read(DnsStream stream, void buf, size_t count) {
	191	ssize_t ss;
	192
	193	assert(stream);
	194	assert(stream->encrypted);
	195	assert(stream->dnstls_data.session);
	196	assert(buf);
	197
	198	ss = gnutls_record_recv(stream->dnstls_data.session, buf, count);
	199	if (ss < 0)
	200	switch(ss) {
	201	case GNUTLS_E_INTERRUPTED:
	202	return -EINTR;
	203	case GNUTLS_E_AGAIN:
	204	return -EAGAIN;
	205	default:
baaa35ad ZJS	206	return log_debug_errno(SYNTHETIC_ERRNO(EPIPE),
	207	"Failed to invoke gnutls_record_recv: %s",
	208	gnutls_strerror(ss));
6016fcb0 IT	209	}
	210
	211	return ss;
	212	}
	213
e22c5b20	214	void dnstls_server_free(DnsServer *server) {
6016fcb0 IT	215	assert(server);
6016fcb0 IT	216
e22c5b20 IT	217	if (server->dnstls_data.session_data.data)
e22c5b20 IT	218	gnutls_free(server->dnstls_data.session_data.data);
6016fcb0 IT	219	}
6016fcb0 IT	220
71a681ae	221	int dnstls_manager_init(Manager *manager) {
e22c5b20 IT	222	int r;
e22c5b20 IT	223	assert(manager);
6016fcb0	224
71a681ae	225	r = gnutls_certificate_allocate_credentials(&manager->dnstls_data.cert_cred);
e22c5b20	226	if (r < 0)
71a681ae IT	227	return -ENOMEM;
71a681ae IT	228
4310bfc2 IT	229	r = gnutls_certificate_set_x509_system_trust(manager->dnstls_data.cert_cred);
	230	if (r < 0)
	231	log_warning("Failed to load system trust store: %s", gnutls_strerror(r));
	232
71a681ae	233	return 0;
e22c5b20	234	}
6016fcb0	235
e22c5b20 IT	236	void dnstls_manager_free(Manager *manager) {
	237	assert(manager);
	238
	239	if (manager->dnstls_data.cert_cred)
	240	gnutls_certificate_free_credentials(manager->dnstls_data.cert_cred);
6016fcb0	241	}