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-rw-r--r--src/resolve/resolved-dnstls-openssl.c353
1 files changed, 353 insertions, 0 deletions
diff --git a/src/resolve/resolved-dnstls-openssl.c b/src/resolve/resolved-dnstls-openssl.c
new file mode 100644
index 0000000..f269e4d
--- /dev/null
+++ b/src/resolve/resolved-dnstls-openssl.c
@@ -0,0 +1,353 @@
+/* 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 <openssl/bio.h>
+#include <openssl/err.h>
+
+#include "io-util.h"
+#include "resolved-dns-stream.h"
+#include "resolved-dnstls.h"
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(SSL*, SSL_free);
+DEFINE_TRIVIAL_CLEANUP_FUNC(BIO*, BIO_free);
+
+static int dnstls_flush_write_buffer(DnsStream *stream) {
+ ssize_t ss;
+
+ assert(stream);
+ assert(stream->encrypted);
+
+ if (stream->dnstls_data.write_buffer->length > 0) {
+ assert(stream->dnstls_data.write_buffer->data);
+
+ struct iovec iov[1];
+ iov[0] = IOVEC_MAKE(stream->dnstls_data.write_buffer->data,
+ stream->dnstls_data.write_buffer->length);
+ ss = dns_stream_writev(stream, iov, 1, DNS_STREAM_WRITE_TLS_DATA);
+ if (ss < 0) {
+ if (ss == -EAGAIN)
+ stream->dnstls_events |= EPOLLOUT;
+
+ return ss;
+ } else {
+ stream->dnstls_data.write_buffer->length -= ss;
+ stream->dnstls_data.write_buffer->data += ss;
+
+ if (stream->dnstls_data.write_buffer->length > 0) {
+ stream->dnstls_events |= EPOLLOUT;
+ return -EAGAIN;
+ }
+ }
+ }
+
+ return 0;
+}
+
+int dnstls_stream_connect_tls(DnsStream *stream, DnsServer *server) {
+ _cleanup_(BIO_freep) BIO *rb = NULL, *wb = NULL;
+ _cleanup_(SSL_freep) SSL *s = NULL;
+ int error, r;
+
+ assert(stream);
+ assert(server);
+
+ rb = BIO_new_socket(stream->fd, 0);
+ if (!rb)
+ return -ENOMEM;
+
+ wb = BIO_new(BIO_s_mem());
+ if (!wb)
+ return -ENOMEM;
+
+ BIO_get_mem_ptr(wb, &stream->dnstls_data.write_buffer);
+
+ s = SSL_new(server->dnstls_data.ctx);
+ if (!s)
+ return -ENOMEM;
+
+ SSL_set_connect_state(s);
+ SSL_set_session(s, server->dnstls_data.session);
+ SSL_set_bio(s, TAKE_PTR(rb), TAKE_PTR(wb));
+
+ ERR_clear_error();
+ stream->dnstls_data.handshake = SSL_do_handshake(s);
+ if (stream->dnstls_data.handshake <= 0) {
+ error = SSL_get_error(s, stream->dnstls_data.handshake);
+ if (!IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
+ char errbuf[256];
+
+ ERR_error_string_n(error, errbuf, sizeof(errbuf));
+ log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
+ return -ECONNREFUSED;
+ }
+ }
+
+ stream->encrypted = true;
+
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0 && r != -EAGAIN)
+ return r;
+
+ 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, uint32_t revents) {
+ int error, r;
+
+ assert(stream);
+ assert(stream->encrypted);
+ assert(stream->dnstls_data.ssl);
+
+ /* Flush write buffer when requested by OpenSSL */
+ if ((revents & EPOLLOUT) && (stream->dnstls_events & EPOLLOUT)) {
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+ }
+
+ if (stream->dnstls_data.shutdown) {
+ ERR_clear_error();
+ r = SSL_shutdown(stream->dnstls_data.ssl);
+ if (r == 0) {
+ stream->dnstls_events = 0;
+
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ 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;
+
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ return -EAGAIN;
+ } else if (error == SSL_ERROR_SYSCALL) {
+ if (errno > 0)
+ log_debug_errno(errno, "Failed to invoke SSL_shutdown, ignoring: %m");
+ } else {
+ char errbuf[256];
+
+ ERR_error_string_n(error, errbuf, sizeof(errbuf));
+ log_debug("Failed to invoke SSL_shutdown, ignoring: %s", errbuf);
+ }
+ }
+
+ stream->dnstls_events = 0;
+ stream->dnstls_data.shutdown = false;
+
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ dns_stream_unref(stream);
+ return DNSTLS_STREAM_CLOSED;
+ } else if (stream->dnstls_data.handshake <= 0) {
+ ERR_clear_error();
+ 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;
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ return -EAGAIN;
+ } else {
+ char errbuf[256];
+
+ ERR_error_string_n(error, errbuf, sizeof(errbuf));
+ return log_debug_errno(SYNTHETIC_ERRNO(ECONNREFUSED),
+ "Failed to invoke SSL_do_handshake: %s",
+ errbuf);
+ }
+ }
+
+ stream->dnstls_events = 0;
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dnstls_stream_shutdown(DnsStream *stream, int error) {
+ int ssl_error, r;
+ SSL_SESSION *s;
+
+ assert(stream);
+ assert(stream->encrypted);
+ assert(stream->dnstls_data.ssl);
+
+ if (stream->server) {
+ s = SSL_get1_session(stream->dnstls_data.ssl);
+ if (s) {
+ if (stream->server->dnstls_data.session)
+ SSL_SESSION_free(stream->server->dnstls_data.session);
+
+ stream->server->dnstls_data.session = s;
+ }
+ }
+
+ if (error == ETIMEDOUT) {
+ ERR_clear_error();
+ r = SSL_shutdown(stream->dnstls_data.ssl);
+ if (r == 0) {
+ if (!stream->dnstls_data.shutdown) {
+ stream->dnstls_data.shutdown = true;
+ dns_stream_ref(stream);
+ }
+
+ stream->dnstls_events = 0;
+
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ 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;
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0 && r != -EAGAIN)
+ return r;
+
+ if (!stream->dnstls_data.shutdown) {
+ stream->dnstls_data.shutdown = true;
+ dns_stream_ref(stream);
+ }
+ return -EAGAIN;
+ } else if (ssl_error == SSL_ERROR_SYSCALL) {
+ if (errno > 0)
+ log_debug_errno(errno, "Failed to invoke SSL_shutdown, ignoring: %m");
+ } else {
+ char errbuf[256];
+
+ ERR_error_string_n(ssl_error, errbuf, sizeof(errbuf));
+ log_debug("Failed to invoke SSL_shutdown, ignoring: %s", errbuf);
+ }
+ }
+
+ stream->dnstls_events = 0;
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+ssize_t dnstls_stream_write(DnsStream *stream, const char *buf, size_t count) {
+ int error, r;
+ ssize_t ss;
+
+ assert(stream);
+ assert(stream->encrypted);
+ assert(stream->dnstls_data.ssl);
+ assert(buf);
+
+ ERR_clear_error();
+ ss = r = SSL_write(stream->dnstls_data.ssl, buf, count);
+ 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;
+ ss = -EAGAIN;
+ } else if (error == SSL_ERROR_ZERO_RETURN) {
+ stream->dnstls_events = 0;
+ ss = 0;
+ } else {
+ char errbuf[256];
+
+ ERR_error_string_n(error, errbuf, sizeof(errbuf));
+ log_debug("Failed to invoke SSL_write: %s", errbuf);
+ stream->dnstls_events = 0;
+ ss = -EPIPE;
+ }
+ } else
+ stream->dnstls_events = 0;
+
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ return ss;
+}
+
+ssize_t dnstls_stream_read(DnsStream *stream, void *buf, size_t count) {
+ int error, r;
+ ssize_t ss;
+
+ assert(stream);
+ assert(stream->encrypted);
+ assert(stream->dnstls_data.ssl);
+ assert(buf);
+
+ ERR_clear_error();
+ ss = r = SSL_read(stream->dnstls_data.ssl, buf, count);
+ 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;
+ ss = -EAGAIN;
+ } else if (error == SSL_ERROR_ZERO_RETURN) {
+ stream->dnstls_events = 0;
+ ss = 0;
+ } else {
+ char errbuf[256];
+
+ ERR_error_string_n(error, errbuf, sizeof(errbuf));
+ log_debug("Failed to invoke SSL_read: %s", errbuf);
+ stream->dnstls_events = 0;
+ ss = -EPIPE;
+ }
+ } else
+ stream->dnstls_events = 0;
+
+ /* flush write buffer in cache of renegotiation */
+ r = dnstls_flush_write_buffer(stream);
+ if (r < 0)
+ return r;
+
+ 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);
+
+ if (server->dnstls_data.session)
+ SSL_SESSION_free(server->dnstls_data.session);
+}
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