src/resolve/resolved-dnstls-openssl.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #if !ENABLE_DNS_OVER_TLS || !DNS_OVER_TLS_USE_OPENSSL
   4 #error This source file requires DNS-over-TLS to be enabled and OpenSSL to be available.
   5 #endif
   6
   7 #include "resolved-dnstls.h"
   8 #include "resolved-dns-stream.h"
   9
  10 #include <openssl/bio.h>
  11 #include <openssl/err.h>
  12
  13 DEFINE_TRIVIAL_CLEANUP_FUNC(SSL*, SSL_free);
  14 DEFINE_TRIVIAL_CLEANUP_FUNC(BIO*, BIO_free);
  15
  16 static int dnstls_flush_write_buffer(DnsStream *stream) {
  17         ssize_t ss;
  18
  19         assert(stream);
  20         assert(stream->encrypted);
  21
  22         if (stream->dnstls_data.write_buffer->length > 0) {
  23                 assert(stream->dnstls_data.write_buffer->data);
  24
  25                 struct iovec iov[1];
  26                 iov[0].iov_base = stream->dnstls_data.write_buffer->data;
  27                 iov[0].iov_len = stream->dnstls_data.write_buffer->length;
  28                 ss = dns_stream_writev(stream, iov, 1, DNS_STREAM_WRITE_TLS_DATA);
  29                 if (ss < 0) {
  30                         if (ss == -EAGAIN)
  31                                 stream->dnstls_events |= EPOLLOUT;
  32
  33                         return ss;
  34                 } else {
  35                         stream->dnstls_data.write_buffer->length -= ss;
  36                         stream->dnstls_data.write_buffer->data += ss;
  37
  38                         if (stream->dnstls_data.write_buffer->length > 0) {
  39                                 stream->dnstls_events |= EPOLLOUT;
  40                                 return -EAGAIN;
  41                         }
  42                 }
  43         }
  44
  45         return 0;
  46 }
  47
  48 int dnstls_stream_connect_tls(DnsStream *stream, DnsServer *server) {
  49         _cleanup_(BIO_freep) BIO *rb = NULL, *wb = NULL;
  50         _cleanup_(SSL_freep) SSL *s = NULL;
  51         int error, r;
  52
  53         assert(stream);
  54         assert(server);
  55
  56         rb = BIO_new_socket(stream->fd, 0);
  57         if (!rb)
  58                 return -ENOMEM;
  59
  60         wb = BIO_new(BIO_s_mem());
  61         if (!wb)
  62                 return -ENOMEM;
  63
  64         BIO_get_mem_ptr(wb, &stream->dnstls_data.write_buffer);
  65
  66         s = SSL_new(server->dnstls_data.ctx);
  67         if (!s)
  68                 return -ENOMEM;
  69
  70         SSL_set_connect_state(s);
  71         SSL_set_session(s, server->dnstls_data.session);
  72         SSL_set_bio(s, TAKE_PTR(rb), TAKE_PTR(wb));
  73
  74         ERR_clear_error();
  75         stream->dnstls_data.handshake = SSL_do_handshake(s);
  76         if (stream->dnstls_data.handshake <= 0) {
  77                 error = SSL_get_error(s, stream->dnstls_data.handshake);
  78                 if (!IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
  79                         char errbuf[256];
  80
  81                         ERR_error_string_n(error, errbuf, sizeof(errbuf));
  82                         log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
  83                         return -ECONNREFUSED;
  84                 }
  85         }
  86
  87         stream->encrypted = true;
  88
  89         r = dnstls_flush_write_buffer(stream);
  90         if (r < 0 && r != -EAGAIN)
  91                 return r;
  92
  93         stream->dnstls_data.ssl = TAKE_PTR(s);
  94
  95         return 0;
  96 }
  97
  98 void dnstls_stream_free(DnsStream *stream) {
  99         assert(stream);
 100         assert(stream->encrypted);
 101
 102         if (stream->dnstls_data.ssl)
 103                 SSL_free(stream->dnstls_data.ssl);
 104 }
 105
 106 int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
 107         int error, r;
 108
 109         assert(stream);
 110         assert(stream->encrypted);
 111         assert(stream->dnstls_data.ssl);
 112
 113         /* Flush write buffer when requested by OpenSSL */
 114         if ((revents & EPOLLOUT) && (stream->dnstls_events & EPOLLOUT)) {
 115                 r = dnstls_flush_write_buffer(stream);
 116                 if (r < 0)
 117                         return r;
 118         }
 119
 120         if (stream->dnstls_data.shutdown) {
 121                 ERR_clear_error();
 122                 r = SSL_shutdown(stream->dnstls_data.ssl);
 123                 if (r <= 0) {
 124                         error = SSL_get_error(stream->dnstls_data.ssl, r);
 125                         if (r == 0 || IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
 126                                 if (r < 0)
 127                                         stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
 128
 129                                 r = dnstls_flush_write_buffer(stream);
 130                                 if (r < 0)
 131                                         return r;
 132
 133                                 return -EAGAIN;
 134                         } else {
 135                                 char errbuf[256];
 136
 137                                 ERR_error_string_n(error, errbuf, sizeof(errbuf));
 138                                 log_debug("Failed to invoke SSL_shutdown: %s", errbuf);
 139                         }
 140                 }
 141
 142                 r = dnstls_flush_write_buffer(stream);
 143                 if (r < 0)
 144                         return r;
 145
 146                 stream->dnstls_events = 0;
 147                 stream->dnstls_data.shutdown = false;
 148                 dns_stream_unref(stream);
 149                 return DNSTLS_STREAM_CLOSED;
 150         } else if (stream->dnstls_data.handshake <= 0) {
 151                 ERR_clear_error();
 152                 stream->dnstls_data.handshake = SSL_do_handshake(stream->dnstls_data.ssl);
 153                 if (stream->dnstls_data.handshake <= 0) {
 154                         error = SSL_get_error(stream->dnstls_data.ssl, stream->dnstls_data.handshake);
 155                         if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
 156                                 stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
 157                                 r = dnstls_flush_write_buffer(stream);
 158                                 if (r < 0)
 159                                         return r;
 160
 161                                 return -EAGAIN;
 162                         } else {
 163                                 char errbuf[256];
 164
 165                                 ERR_error_string_n(error, errbuf, sizeof(errbuf));
 166                                 log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
 167                                 return -ECONNREFUSED;
 168                         }
 169                 }
 170
 171                 stream->dnstls_events = 0;
 172                 r = dnstls_flush_write_buffer(stream);
 173                 if (r < 0)
 174                         return r;
 175         }
 176
 177         return 0;
 178 }
 179
 180 int dnstls_stream_shutdown(DnsStream *stream, int error) {
 181         int ssl_error, r;
 182         SSL_SESSION *s;
 183
 184         assert(stream);
 185         assert(stream->encrypted);
 186         assert(stream->dnstls_data.ssl);
 187
 188         if (stream->server) {
 189                 s = SSL_get1_session(stream->dnstls_data.ssl);
 190                 if (s) {
 191                         if (stream->server->dnstls_data.session)
 192                                 SSL_SESSION_free(stream->server->dnstls_data.session);
 193
 194                         stream->server->dnstls_data.session = s;
 195                 }
 196         }
 197
 198         if (error == ETIMEDOUT) {
 199                 ERR_clear_error();
 200                 r = SSL_shutdown(stream->dnstls_data.ssl);
 201                 if (r == 0) {
 202                         if (!stream->dnstls_data.shutdown) {
 203                                 stream->dnstls_data.shutdown = true;
 204                                 dns_stream_ref(stream);
 205                         }
 206
 207                         r = dnstls_flush_write_buffer(stream);
 208                         if (r < 0)
 209                                 return r;
 210
 211                         return -EAGAIN;
 212                 } else if (r < 0) {
 213                         ssl_error = SSL_get_error(stream->dnstls_data.ssl, r);
 214                         if (IN_SET(ssl_error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
 215                                 stream->dnstls_events = ssl_error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
 216                                 r = dnstls_flush_write_buffer(stream);
 217                                 if (r < 0 && r != -EAGAIN)
 218                                         return r;
 219
 220                                 if (!stream->dnstls_data.shutdown) {
 221                                         stream->dnstls_data.shutdown = true;
 222                                         dns_stream_ref(stream);
 223                                 }
 224                                 return -EAGAIN;
 225                         } else {
 226                                 char errbuf[256];
 227
 228                                 ERR_error_string_n(ssl_error, errbuf, sizeof(errbuf));
 229                                 log_debug("Failed to invoke SSL_shutdown: %s", errbuf);
 230                         }
 231                 }
 232
 233                 stream->dnstls_events = 0;
 234                 r = dnstls_flush_write_buffer(stream);
 235                 if (r < 0)
 236                         return r;
 237         }
 238
 239         return 0;
 240 }
 241
 242 ssize_t dnstls_stream_write(DnsStream *stream, const char *buf, size_t count) {
 243         int error, r;
 244         ssize_t ss;
 245
 246         assert(stream);
 247         assert(stream->encrypted);
 248         assert(stream->dnstls_data.ssl);
 249         assert(buf);
 250
 251         ERR_clear_error();
 252         ss = r = SSL_write(stream->dnstls_data.ssl, buf, count);
 253         if (r <= 0) {
 254                 error = SSL_get_error(stream->dnstls_data.ssl, ss);
 255                 if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
 256                         stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
 257                         r = dnstls_flush_write_buffer(stream);
 258                         if (r < 0)
 259                                 return r;
 260
 261                         ss = -EAGAIN;
 262                 } else {
 263                         char errbuf[256];
 264
 265                         ERR_error_string_n(error, errbuf, sizeof(errbuf));
 266                         log_debug("Failed to invoke SSL_write: %s", errbuf);
 267                         ss = -EPIPE;
 268                 }
 269         }
 270
 271         stream->dnstls_events = 0;
 272         r = dnstls_flush_write_buffer(stream);
 273         if (r < 0)
 274                 return r;
 275
 276         return ss;
 277 }
 278
 279 ssize_t dnstls_stream_read(DnsStream *stream, void *buf, size_t count) {
 280         int error, r;
 281         ssize_t ss;
 282
 283         assert(stream);
 284         assert(stream->encrypted);
 285         assert(stream->dnstls_data.ssl);
 286         assert(buf);
 287
 288         ERR_clear_error();
 289         ss = r = SSL_read(stream->dnstls_data.ssl, buf, count);
 290         if (r <= 0) {
 291                 error = SSL_get_error(stream->dnstls_data.ssl, ss);
 292                 if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
 293                         stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
 294
 295                         /* flush write buffer in cache of renegotiation */
 296                         r = dnstls_flush_write_buffer(stream);
 297                         if (r < 0)
 298                                 return r;
 299
 300                         ss = -EAGAIN;
 301                 } else {
 302                         char errbuf[256];
 303
 304                         ERR_error_string_n(error, errbuf, sizeof(errbuf));
 305                         log_debug("Failed to invoke SSL_read: %s", errbuf);
 306                         ss = -EPIPE;
 307                 }
 308         }
 309
 310         stream->dnstls_events = 0;
 311
 312         /* flush write buffer in cache of renegotiation */
 313         r = dnstls_flush_write_buffer(stream);
 314         if (r < 0)
 315                 return r;
 316
 317         return ss;
 318 }
 319
 320 void dnstls_server_init(DnsServer *server) {
 321         assert(server);
 322
 323         server->dnstls_data.ctx = SSL_CTX_new(TLS_client_method());
 324         if (server->dnstls_data.ctx) {
 325                 SSL_CTX_set_min_proto_version(server->dnstls_data.ctx, TLS1_2_VERSION);
 326                 SSL_CTX_set_options(server->dnstls_data.ctx, SSL_OP_NO_COMPRESSION);
 327         }
 328 }
 329
 330 void dnstls_server_free(DnsServer *server) {
 331         assert(server);
 332
 333         if (server->dnstls_data.ctx)
 334                 SSL_CTX_free(server->dnstls_data.ctx);
 335
 336         if (server->dnstls_data.session)
 337                 SSL_SESSION_free(server->dnstls_data.session);
 338 }