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resolved: basic OpenSSL support for DNS-over-TLS 

This provides basic OpenSSL support without optimizations like TCP Fast Open and TLS Session Tickets.
Notice only a single SSL library can be enabled at a time and therefore journald functions provided by GnuTLS will be disabled when using OpenSSL.
Fixes #9531
This commit is contained in:
Iwan Timmer 2018-07-26 22:47:50 +01:00
parent ba6aaf5727
commit 096cbdce13
10 changed files with 294 additions and 13 deletions
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3
README
View File

@ -154,7 +154,8 @@ REQUIREMENTS:
libmicrohttpd (optional)
libpython (optional)
libidn2 or libidn (optional)
gnutls >= 3.1.4 (optional, >= 3.5.3 is necessary to support DNS-over-TLS)
gnutls >= 3.1.4 (optional, >= 3.5.3 is required to support DNS-over-TLS with gnutls)
openssl >= 1.1.0 (optional, required to support DNS-over-TLS with openssl)
elfutils >= 158 (optional)
polkit (optional)
pkg-config

41
meson.build
View File

@ -1013,6 +1013,18 @@ else
endif
conf.set10('HAVE_GNUTLS', have)
want_openssl = get_option('openssl')
if want_openssl != 'false' and not fuzzer_build
libopenssl = dependency('openssl',
version : '>= 1.1.0',
required : want_openssl == 'true')
have = libopenssl.found()
else
have = false
libopenssl = []
endif
conf.set10('HAVE_OPENSSL', have)
want_elfutils = get_option('elfutils')
if want_elfutils != 'false' and not fuzzer_build
libdw = dependency('libdw',
@ -1136,15 +1148,30 @@ substs.set('DEFAULT_DNSSEC_MODE', default_dnssec)
dns_over_tls = get_option('dns-over-tls')
if dns_over_tls != 'false'
have = (conf.get('HAVE_GNUTLS') == 1 and
libgnutls.version().version_compare('>=3.5.3'))
if dns_over_tls == 'true' and not have
error('DNS-over-TLS support was requested, but dependencies are not available')
if dns_over_tls == 'openssl'
have_gnutls = false
else
have_gnutls = (conf.get('HAVE_GNUTLS') == 1 and libgnutls.version().version_compare('>= 3.5.3'))
if dns_over_tls == 'gnutls' and not have_gnutls
error('DNS-over-TLS support was requested with gnutls, but dependencies are not available')
endif
endif
if dns_over_tls == 'gnutls' or have_gnutls
have_openssl = false
else
have_openssl = conf.get('HAVE_OPENSSL') == 1
if dns_over_tls != 'auto' and not have_openssl
str = dns_over_tls == 'openssl' ? ' with openssl' : ''
error('DNS-over-TLS support was requested$0$, but dependencies are not available'.format(str))
endif
endif
have = have_gnutls or have_openssl
else
have = false
have = have_gnutls = have_openssl = false
endif
conf.set10('ENABLE_DNS_OVER_TLS', have)
conf.set10('DNS_OVER_TLS_USE_GNUTLS', have_gnutls)
conf.set10('DNS_OVER_TLS_USE_OPENSSL', have_openssl)
default_dns_over_tls = get_option('default-dns-over-tls')
if fuzzer_build
@ -2950,6 +2977,7 @@ foreach tuple : [
['qrencode'],
['microhttpd'],
['gnutls'],
['openssl'],
['libcurl'],
['idn'],
['libidn2'],
@ -2976,7 +3004,8 @@ foreach tuple : [
['localed'],
['networkd'],
['resolve'],
['DNS-over-TLS'],
['DNS-over-TLS(gnutls)', conf.get('DNS_OVER_TLS_USE_GNUTLS') == 1],
['DNS-over-TLS(openssl)', conf.get('DNS_OVER_TLS_USE_OPENSSL') == 1],
['coredump'],
['polkit'],
['legacy pkla', install_polkit_pkla],

4
meson_options.txt
View File

@ -195,7 +195,7 @@ option('default-dns-over-tls', type : 'combo',
description : 'default DNS-over-TLS mode',
choices : ['opportunistic', 'no'],
value : 'no')
option('dns-over-tls', type : 'combo', choices : ['auto', 'true', 'false'],
option('dns-over-tls', type : 'combo', choices : ['auto', 'gnutls', 'openssl', 'true', 'false'],
description : 'DNS-over-TLS support')
option('dns-servers', type : 'string',
description : 'space-separated list of default DNS servers',
@ -255,6 +255,8 @@ option('gcrypt', type : 'combo', choices : ['auto', 'true', 'false'],
description : 'gcrypt support')
option('gnutls', type : 'combo', choices : ['auto', 'true', 'false'],
description : 'gnutls support')
option('openssl', type : 'combo', choices : ['auto', 'true', 'false'],
description : 'openssl support')
option('elfutils', type : 'combo', choices : ['auto', 'true', 'false'],
description : 'elfutils support')
option('zlib', type : 'combo', choices : ['auto', 'true', 'false'],

11
src/resolve/meson.build
View File

@ -142,8 +142,15 @@ systemd_resolved_sources += [resolved_gperf_c, resolved_dnssd_gperf_c]
systemd_resolved_dependencies = [threads, libgpg_error, libm, libidn]
if conf.get('ENABLE_DNS_OVER_TLS') == 1
systemd_resolved_sources += [files(['resolved-dnstls-gnutls.c', 'resolved-dnstls-gnutls.h'])]
systemd_resolved_dependencies += [libgnutls]
if conf.get('DNS_OVER_TLS_USE_GNUTLS') == 1
systemd_resolved_sources += [files(['resolved-dnstls-gnutls.c', 'resolved-dnstls-gnutls.h'])]
systemd_resolved_dependencies += [libgnutls]
elif conf.get('DNS_OVER_TLS_USE_OPENSSL') == 1
systemd_resolved_sources += [files(['resolved-dnstls-openssl.c', 'resolved-dnstls-openssl.h'])]
systemd_resolved_dependencies += [libopenssl]
else
error('unknown dependency for supporting DNS-over-TLS')
endif
endif
if conf.get('ENABLE_RESOLVE') == 1

2
src/resolve/resolved-dns-stream.c
View File

@ -234,6 +234,8 @@ ssize_t dns_stream_writev(DnsStream *s, const struct iovec *iov, size_t iovcnt,
r = -EAGAIN;
} else if (errno == EINPROGRESS)
r = -EAGAIN;
else
r = -errno;
} else
s->tfo_salen = 0; /* connection is made */
} else {

2
src/resolve/resolved-dnstls-gnutls.c
View File

@ -1,6 +1,6 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#if !ENABLE_DNS_OVER_TLS || !HAVE_GNUTLS
#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

2
src/resolve/resolved-dnstls-gnutls.h
View File

@ -1,7 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
#if !ENABLE_DNS_OVER_TLS || !HAVE_GNUTLS
#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

216
src/resolve/resolved-dnstls-openssl.c Normal file
View File

@ -0,0 +1,216 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#if !ENABLE_DNS_OVER_TLS || !DNS_OVER_TLS_USE_OPENSSL
#error This source file requires DNS-over-TLS to be enabled and OpenSSL to be available.
#endif
#include "resolved-dnstls.h"
#include "resolved-dns-stream.h"
#include <openssl/bio.h>
#include <openssl/err.h>
DEFINE_TRIVIAL_CLEANUP_FUNC(SSL*, SSL_free);
DEFINE_TRIVIAL_CLEANUP_FUNC(BIO*, BIO_free);
int dnstls_stream_connect_tls(DnsStream *stream, DnsServer *server) {
_cleanup_(SSL_freep) SSL *s = NULL;
_cleanup_(BIO_freep) BIO *b = NULL;
assert(stream);
assert(server);
b = BIO_new_socket(stream->fd, 0);
if (!b)
return -ENOMEM;
s = SSL_new(server->dnstls_data.ctx);
if (!s)
return -ENOMEM;
SSL_set_connect_state(s);
SSL_set_bio(s, b, b);
b = NULL;
/* DNS-over-TLS using OpenSSL doesn't support TCP Fast Open yet */
connect(stream->fd, &stream->tfo_address.sa, stream->tfo_salen);
stream->tfo_salen = 0;
stream->encrypted = true;
stream->dnstls_events = EPOLLOUT;
stream->dnstls_data.ssl = TAKE_PTR(s);
return 0;
}
void dnstls_stream_free(DnsStream *stream) {
assert(stream);
assert(stream->encrypted);
if (stream->dnstls_data.ssl)
SSL_free(stream->dnstls_data.ssl);
}
int dnstls_stream_on_io(DnsStream *stream) {
int r;
int error;
assert(stream);
assert(stream->encrypted);
assert(stream->dnstls_data.ssl);
if (stream->dnstls_data.shutdown) {
r = SSL_shutdown(stream->dnstls_data.ssl);
if (r == 0)
return -EAGAIN;
else if (r < 0) {
error = SSL_get_error(stream->dnstls_data.ssl, r);
if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
return -EAGAIN;
} else {
char errbuf[256];
ERR_error_string_n(error, errbuf, sizeof(errbuf));
log_debug("Failed to invoke SSL_shutdown: %s", errbuf);
}
}
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 = SSL_do_handshake(stream->dnstls_data.ssl);
if (stream->dnstls_data.handshake <= 0) {
error = SSL_get_error(stream->dnstls_data.ssl, stream->dnstls_data.handshake);
if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
return -EAGAIN;
} else {
char errbuf[256];
ERR_error_string_n(error, errbuf, sizeof(errbuf));
log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
return -ECONNREFUSED;
}
}
stream->dnstls_events = 0;
}
return 0;
}
int dnstls_stream_shutdown(DnsStream *stream, int error) {
int r;
int ssl_error;
SSL_SESSION *s;
assert(stream);
assert(stream->encrypted);
assert(stream->dnstls_data.ssl);
if (error == ETIMEDOUT) {
r = SSL_shutdown(stream->dnstls_data.ssl);
if (r == 0) {
if (!stream->dnstls_data.shutdown) {
stream->dnstls_data.shutdown = true;
dns_stream_ref(stream);
}
return -EAGAIN;
} else if (r < 0) {
ssl_error = SSL_get_error(stream->dnstls_data.ssl, r);
if (IN_SET(ssl_error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
stream->dnstls_events = ssl_error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
if (!stream->dnstls_data.shutdown) {
stream->dnstls_data.shutdown = true;
dns_stream_ref(stream);
}
return -EAGAIN;
} else {
char errbuf[256];
ERR_error_string_n(ssl_error, errbuf, sizeof(errbuf));
log_debug("Failed to invoke SSL_shutdown: %s", errbuf);
}
}
}
return 0;
}
ssize_t dnstls_stream_write(DnsStream *stream, const char *buf, size_t count) {
int r;
int error;
ssize_t ss;
assert(stream);
assert(stream->encrypted);
assert(stream->dnstls_data.ssl);
assert(buf);
ss = r = SSL_write(stream->dnstls_data.ssl, buf, count);
if (r <= 0) {
error = SSL_get_error(stream->dnstls_data.ssl, ss);
if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
ss = -EAGAIN;
} else {
char errbuf[256];
ERR_error_string_n(error, errbuf, sizeof(errbuf));
log_debug("Failed to invoke SSL_read: %s", errbuf);
ss = -EPIPE;
}
}
stream->dnstls_events = 0;
return ss;
}
ssize_t dnstls_stream_read(DnsStream *stream, void *buf, size_t count) {
int r;
int error;
ssize_t ss;
assert(stream);
assert(stream->encrypted);
assert(stream->dnstls_data.ssl);
assert(buf);
ss = r = SSL_read(stream->dnstls_data.ssl, buf, count);
if (r <= 0) {
error = SSL_get_error(stream->dnstls_data.ssl, ss);
if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
ss = -EAGAIN;
} else {
char errbuf[256];
ERR_error_string_n(error, errbuf, sizeof(errbuf));
log_debug("Failed to invoke SSL_read: %s", errbuf);
ss = -EPIPE;
}
}
stream->dnstls_events = 0;
return ss;
}
void dnstls_server_init(DnsServer *server) {
assert(server);
server->dnstls_data.ctx = SSL_CTX_new(TLS_client_method());
if (server->dnstls_data.ctx) {
SSL_CTX_set_min_proto_version(server->dnstls_data.ctx, TLS1_2_VERSION);
SSL_CTX_set_options(server->dnstls_data.ctx, SSL_OP_NO_COMPRESSION);
}
}
void dnstls_server_free(DnsServer *server) {
assert(server);
if (server->dnstls_data.ctx)
SSL_CTX_free(server->dnstls_data.ctx);
}

20
src/resolve/resolved-dnstls-openssl.h Normal file
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@ -0,0 +1,20 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
#if !ENABLE_DNS_OVER_TLS || !DNS_OVER_TLS_USE_OPENSSL
#error This source file requires DNS-over-TLS to be enabled and OpenSSL to be available.
#endif
#include <stdbool.h>
#include <openssl/ssl.h>
struct DnsTlsServerData {
SSL_CTX *ctx;
};
struct DnsTlsStreamData {
int handshake;
bool shutdown;
SSL *ssl;
};

6
src/resolve/resolved-dnstls.h
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@ -8,8 +8,12 @@
typedef struct DnsTlsServerData DnsTlsServerData;
typedef struct DnsTlsStreamData DnsTlsStreamData;
#if HAVE_GNUTLS
#if DNS_OVER_TLS_USE_GNUTLS
#include "resolved-dnstls-gnutls.h"
#elif DNS_OVER_TLS_USE_OPENSSL
#include "resolved-dnstls-openssl.h"
#else
#error Unknown dependency for supporting DNS-over-TLS
#endif
#include "resolved-dns-stream.h"