+ SSL_shutdown(*sslp);
+ }
+
+SSL_free(*sslp);
+*sslp = NULL;
+
+*fdp = -1;
+}
+
+
+
+
+/*************************************************
+* Let tls_require_ciphers be checked at startup *
+*************************************************/
+
+/* The tls_require_ciphers option, if set, must be something which the
+library can parse.
+
+Returns: NULL on success, or error message
+*/
+
+uschar *
+tls_validate_require_cipher(void)
+{
+SSL_CTX *ctx;
+uschar *s, *expciphers, *err;
+
+/* this duplicates from tls_init(), we need a better "init just global
+state, for no specific purpose" singleton function of our own */
+
+SSL_load_error_strings();
+OpenSSL_add_ssl_algorithms();
+#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
+/* SHA256 is becoming ever more popular. This makes sure it gets added to the
+list of available digests. */
+EVP_add_digest(EVP_sha256());
+#endif
+
+if (!(tls_require_ciphers && *tls_require_ciphers))
+ return NULL;
+
+if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
+ return US"failed to expand tls_require_ciphers";
+
+if (!(expciphers && *expciphers))
+ return NULL;
+
+/* normalisation ripped from above */
+s = expciphers;
+while (*s != 0) { if (*s == '_') *s = '-'; s++; }
+
+err = NULL;
+
+ctx = SSL_CTX_new(SSLv23_server_method());
+if (!ctx)
+ {
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
+ }
+
+DEBUG(D_tls)
+ debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
+
+if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
+ {
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
+ }
+
+SSL_CTX_free(ctx);
+
+return err;
+}
+
+
+
+
+/*************************************************
+* Report the library versions. *
+*************************************************/
+
+/* There have historically been some issues with binary compatibility in
+OpenSSL libraries; if Exim (like many other applications) is built against
+one version of OpenSSL but the run-time linker picks up another version,
+it can result in serious failures, including crashing with a SIGSEGV. So
+report the version found by the compiler and the run-time version.
+
+Note: some OS vendors backport security fixes without changing the version
+number/string, and the version date remains unchanged. The _build_ date
+will change, so we can more usefully assist with version diagnosis by also
+reporting the build date.
+
+Arguments: a FILE* to print the results to
+Returns: nothing
+*/
+
+void
+tls_version_report(FILE *f)
+{
+fprintf(f, "Library version: OpenSSL: Compile: %s\n"
+ " Runtime: %s\n"
+ " : %s\n",
+ OPENSSL_VERSION_TEXT,
+ SSLeay_version(SSLEAY_VERSION),
+ SSLeay_version(SSLEAY_BUILT_ON));
+/* third line is 38 characters for the %s and the line is 73 chars long;
+the OpenSSL output includes a "built on: " prefix already. */
+}
+
+
+
+
+/*************************************************
+* Random number generation *
+*************************************************/
+
+/* Pseudo-random number generation. The result is not expected to be
+cryptographically strong but not so weak that someone will shoot themselves
+in the foot using it as a nonce in input in some email header scheme or
+whatever weirdness they'll twist this into. The result should handle fork()
+and avoid repeating sequences. OpenSSL handles that for us.
+
+Arguments:
+ max range maximum
+Returns a random number in range [0, max-1]
+*/
+
+int
+vaguely_random_number(int max)
+{
+unsigned int r;
+int i, needed_len;
+static pid_t pidlast = 0;
+pid_t pidnow;
+uschar *p;
+uschar smallbuf[sizeof(r)];
+
+if (max <= 1)
+ return 0;
+
+pidnow = getpid();
+if (pidnow != pidlast)
+ {
+ /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
+ is unique for each thread", this doesn't apparently apply across processes,
+ so our own warning from vaguely_random_number_fallback() applies here too.
+ Fix per PostgreSQL. */
+ if (pidlast != 0)
+ RAND_cleanup();
+ pidlast = pidnow;
+ }
+
+/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
+if (!RAND_status())
+ {
+ randstuff r;
+ gettimeofday(&r.tv, NULL);
+ r.p = getpid();
+
+ RAND_seed((uschar *)(&r), sizeof(r));
+ }
+/* We're after pseudo-random, not random; if we still don't have enough data
+in the internal PRNG then our options are limited. We could sleep and hope
+for entropy to come along (prayer technique) but if the system is so depleted
+in the first place then something is likely to just keep taking it. Instead,
+we'll just take whatever little bit of pseudo-random we can still manage to
+get. */
+
+needed_len = sizeof(r);
+/* Don't take 8 times more entropy than needed if int is 8 octets and we were
+asked for a number less than 10. */
+for (r = max, i = 0; r; ++i)
+ r >>= 1;
+i = (i + 7) / 8;
+if (i < needed_len)
+ needed_len = i;
+
+/* We do not care if crypto-strong */
+i = RAND_pseudo_bytes(smallbuf, needed_len);
+if (i < 0)
+ {
+ DEBUG(D_all)
+ debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
+ return vaguely_random_number_fallback(max);
+ }
+
+r = 0;
+for (p = smallbuf; needed_len; --needed_len, ++p)
+ {
+ r *= 256;
+ r += *p;
+ }
+
+/* We don't particularly care about weighted results; if someone wants
+smooth distribution and cares enough then they should submit a patch then. */
+return r % max;
+}
+
+
+
+
+/*************************************************
+* OpenSSL option parse *
+*************************************************/
+
+/* Parse one option for tls_openssl_options_parse below
+
+Arguments:
+ name one option name
+ value place to store a value for it
+Returns success or failure in parsing
+*/
+
+struct exim_openssl_option {
+ uschar *name;
+ long value;
+};
+/* We could use a macro to expand, but we need the ifdef and not all the
+options document which version they were introduced in. Policylet: include
+all options unless explicitly for DTLS, let the administrator choose which
+to apply.
+
+This list is current as of:
+ ==> 1.0.1b <==
+Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
+*/
+static struct exim_openssl_option exim_openssl_options[] = {
+/* KEEP SORTED ALPHABETICALLY! */
+#ifdef SSL_OP_ALL
+ { US"all", SSL_OP_ALL },
+#endif
+#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
+ { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
+#endif
+#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
+ { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
+#endif
+#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
+ { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
+#endif
+#ifdef SSL_OP_EPHEMERAL_RSA
+ { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
+#endif
+#ifdef SSL_OP_LEGACY_SERVER_CONNECT
+ { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
+#endif
+#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
+ { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
+#endif
+#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
+ { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
+#endif
+#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
+ { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
+#endif
+#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
+ { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
+#endif
+#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
+ { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
+#endif
+#ifdef SSL_OP_NO_COMPRESSION
+ { US"no_compression", SSL_OP_NO_COMPRESSION },
+#endif
+#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
+ { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
+#endif
+#ifdef SSL_OP_NO_SSLv2
+ { US"no_sslv2", SSL_OP_NO_SSLv2 },
+#endif
+#ifdef SSL_OP_NO_SSLv3
+ { US"no_sslv3", SSL_OP_NO_SSLv3 },
+#endif
+#ifdef SSL_OP_NO_TICKET
+ { US"no_ticket", SSL_OP_NO_TICKET },
+#endif
+#ifdef SSL_OP_NO_TLSv1
+ { US"no_tlsv1", SSL_OP_NO_TLSv1 },
+#endif
+#ifdef SSL_OP_NO_TLSv1_1
+#if SSL_OP_NO_TLSv1_1 == 0x00000400L
+ /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
+#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
+#else
+ { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
+#endif
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+ { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
+#endif
+#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
+ { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
+#endif
+#ifdef SSL_OP_SINGLE_DH_USE
+ { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
+#endif
+#ifdef SSL_OP_SINGLE_ECDH_USE
+ { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
+#endif
+#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
+ { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
+#endif
+#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
+ { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
+#endif
+#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
+ { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
+#endif
+#ifdef SSL_OP_TLS_D5_BUG
+ { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
+#endif
+#ifdef SSL_OP_TLS_ROLLBACK_BUG
+ { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
+#endif
+};
+static int exim_openssl_options_size =
+ sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
+
+
+static BOOL
+tls_openssl_one_option_parse(uschar *name, long *value)
+{
+int first = 0;
+int last = exim_openssl_options_size;
+while (last > first)
+ {
+ int middle = (first + last)/2;
+ int c = Ustrcmp(name, exim_openssl_options[middle].name);
+ if (c == 0)
+ {
+ *value = exim_openssl_options[middle].value;
+ return TRUE;
+ }
+ else if (c > 0)
+ first = middle + 1;
+ else
+ last = middle;
+ }
+return FALSE;
+}
+
+
+
+
+/*************************************************
+* OpenSSL option parsing logic *
+*************************************************/
+
+/* OpenSSL has a number of compatibility options which an administrator might
+reasonably wish to set. Interpret a list similarly to decode_bits(), so that
+we look like log_selector.
+
+Arguments:
+ option_spec the administrator-supplied string of options
+ results ptr to long storage for the options bitmap
+Returns success or failure
+*/
+
+BOOL
+tls_openssl_options_parse(uschar *option_spec, long *results)
+{
+long result, item;
+uschar *s, *end;
+uschar keep_c;
+BOOL adding, item_parsed;
+
+result = 0L;
+/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
+ * from default because it increases BEAST susceptibility. */
+#ifdef SSL_OP_NO_SSLv2
+result |= SSL_OP_NO_SSLv2;
+#endif
+
+if (option_spec == NULL)
+ {
+ *results = result;
+ return TRUE;