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-rw-r--r--src/tlscert-gnu.c481
1 files changed, 481 insertions, 0 deletions
diff --git a/src/tlscert-gnu.c b/src/tlscert-gnu.c
new file mode 100644
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--- /dev/null
+++ b/src/tlscert-gnu.c
@@ -0,0 +1,481 @@
+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 2014 - 2018 */
+
+/* This file provides TLS/SSL support for Exim using the GnuTLS library,
+one of the available supported implementations. This file is #included into
+tls.c when USE_GNUTLS has been set.
+*/
+
+#include <gnutls/gnutls.h>
+/* needed for cert checks in verification and DN extraction: */
+#include <gnutls/x509.h>
+/* needed to disable PKCS11 autoload unless requested */
+#if GNUTLS_VERSION_NUMBER >= 0x020c00
+# include <gnutls/pkcs11.h>
+#endif
+
+
+/*****************************************************
+* Export/import a certificate, binary/printable
+******************************************************
+Return: boolean success
+*/
+
+BOOL
+tls_export_cert(uschar * buf, size_t buflen, void * cert)
+{
+size_t sz = buflen;
+rmark reset_point = store_mark();
+BOOL fail;
+const uschar * cp;
+
+if ((fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert,
+ GNUTLS_X509_FMT_PEM, buf, &sz)))
+ {
+ log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
+ gnutls_strerror(fail));
+ return FALSE;
+ }
+if ((cp = string_printing(buf)) != buf)
+ {
+ Ustrncpy(buf, cp, buflen);
+ if (buf[buflen-1])
+ fail = 1;
+ }
+store_reset(reset_point);
+return !fail;
+}
+
+/* On error, NULL out the destination */
+BOOL
+tls_import_cert(const uschar * buf, void ** cert)
+{
+rmark reset_point = store_mark();
+gnutls_datum_t datum;
+gnutls_x509_crt_t crt = *(gnutls_x509_crt_t *)cert;
+int rc;
+
+if (crt)
+ gnutls_x509_crt_deinit(crt);
+else
+ gnutls_global_init();
+
+gnutls_x509_crt_init(&crt);
+
+datum.data = string_unprinting(US buf);
+datum.size = Ustrlen(datum.data);
+if ((rc = gnutls_x509_crt_import(crt, &datum, GNUTLS_X509_FMT_PEM)))
+ {
+ log_write(0, LOG_MAIN, "TLS error in certificate import: %s",
+ gnutls_strerror(rc));
+ crt = NULL;
+ }
+*cert = (void *)crt;
+store_reset(reset_point);
+return rc != 0;
+}
+
+void
+tls_free_cert(void ** cert)
+{
+gnutls_x509_crt_t crt = *(gnutls_x509_crt_t *)cert;
+if (crt)
+ {
+ gnutls_x509_crt_deinit(crt);
+ gnutls_global_deinit();
+ *cert = NULL;
+ }
+}
+
+/*****************************************************
+* Certificate field extraction routines
+*****************************************************/
+
+/* First, some internal service functions */
+
+static uschar *
+g_err(const char * tag, const char * from, int gnutls_err)
+{
+expand_string_message = string_sprintf("%s: %s fail: %s\n",
+ from, tag, gnutls_strerror(gnutls_err));
+return NULL;
+}
+
+
+static uschar *
+time_copy(time_t t, uschar * mod)
+{
+uschar * cp;
+size_t len = 32;
+
+if (mod && Ustrcmp(mod, "int") == 0)
+ return string_sprintf("%u", (unsigned)t);
+
+cp = store_get(len, FALSE);
+if (f.timestamps_utc)
+ {
+ uschar * tz = to_tz(US"GMT0");
+ len = strftime(CS cp, len, "%b %e %T %Y %Z", gmtime(&t));
+ restore_tz(tz);
+ }
+else
+ len = strftime(CS cp, len, "%b %e %T %Y %Z", localtime(&t));
+return len > 0 ? cp : NULL;
+}
+
+
+/**/
+/* Now the extractors, called from expand.c
+Arguments:
+ cert The certificate
+ mod Optional modifiers for the operator
+
+Return:
+ Allocated string with extracted value
+*/
+
+uschar *
+tls_cert_issuer(void * cert, uschar * mod)
+{
+uschar * cp = NULL;
+int ret;
+size_t siz = 0;
+
+if ((ret = gnutls_x509_crt_get_issuer_dn(cert, CS cp, &siz))
+ != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return g_err("gi0", __FUNCTION__, ret);
+
+cp = store_get(siz, TRUE);
+if ((ret = gnutls_x509_crt_get_issuer_dn(cert, CS cp, &siz)) < 0)
+ return g_err("gi1", __FUNCTION__, ret);
+
+return mod ? tls_field_from_dn(cp, mod) : cp;
+}
+
+uschar *
+tls_cert_not_after(void * cert, uschar * mod)
+{
+return time_copy(
+ gnutls_x509_crt_get_expiration_time((gnutls_x509_crt_t)cert),
+ mod);
+}
+
+uschar *
+tls_cert_not_before(void * cert, uschar * mod)
+{
+return time_copy(
+ gnutls_x509_crt_get_activation_time((gnutls_x509_crt_t)cert),
+ mod);
+}
+
+uschar *
+tls_cert_serial_number(void * cert, uschar * mod)
+{
+uschar bin[50], txt[150];
+uschar * sp = bin;
+size_t sz = sizeof(bin);
+int ret;
+
+if ((ret = gnutls_x509_crt_get_serial((gnutls_x509_crt_t)cert,
+ bin, &sz)))
+ return g_err("gs0", __FUNCTION__, ret);
+
+for(uschar * dp = txt; sz; sz--)
+ dp += sprintf(CS dp, "%.2x", *sp++);
+for(sp = txt; sp[0]=='0' && sp[1]; ) sp++; /* leading zeroes */
+return string_copy(sp);
+}
+
+uschar *
+tls_cert_signature(void * cert, uschar * mod)
+{
+uschar * cp1 = NULL;
+uschar * cp2;
+uschar * cp3;
+size_t len = 0;
+int ret;
+
+if ((ret = gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, CS cp1, &len))
+ != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return g_err("gs0", __FUNCTION__, ret);
+
+cp1 = store_get(len*4+1, TRUE);
+if (gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, CS cp1, &len) != 0)
+ return g_err("gs1", __FUNCTION__, ret);
+
+for(cp3 = cp2 = cp1+len; cp1 < cp2; cp1++)
+ cp3 += sprintf(CS cp3, "%.2x ", *cp1);
+cp3[-1]= '\0';
+
+return cp2;
+}
+
+uschar *
+tls_cert_signature_algorithm(void * cert, uschar * mod)
+{
+gnutls_sign_algorithm_t algo =
+ gnutls_x509_crt_get_signature_algorithm((gnutls_x509_crt_t)cert);
+return algo < 0 ? NULL : string_copy(US gnutls_sign_get_name(algo));
+}
+
+uschar *
+tls_cert_subject(void * cert, uschar * mod)
+{
+uschar * cp = NULL;
+int ret;
+size_t siz = 0;
+
+if ((ret = gnutls_x509_crt_get_dn(cert, CS cp, &siz))
+ != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return g_err("gs0", __FUNCTION__, ret);
+
+cp = store_get(siz, TRUE);
+if ((ret = gnutls_x509_crt_get_dn(cert, CS cp, &siz)) < 0)
+ return g_err("gs1", __FUNCTION__, ret);
+
+return mod ? tls_field_from_dn(cp, mod) : cp;
+}
+
+uschar *
+tls_cert_version(void * cert, uschar * mod)
+{
+return string_sprintf("%d", gnutls_x509_crt_get_version(cert));
+}
+
+uschar *
+tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
+{
+uschar * cp1 = NULL;
+uschar * cp2;
+uschar * cp3;
+size_t siz = 0;
+unsigned int crit;
+int ret;
+
+ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert,
+ CS oid, idx, CS cp1, &siz, &crit);
+if (ret != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return g_err("ge0", __FUNCTION__, ret);
+
+cp1 = store_get(siz*4 + 1, TRUE);
+
+ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert,
+ CS oid, idx, CS cp1, &siz, &crit);
+if (ret < 0)
+ return g_err("ge1", __FUNCTION__, ret);
+
+/* binary data, DER encoded */
+
+/* just dump for now */
+for(cp3 = cp2 = cp1+siz; cp1 < cp2; cp1++)
+ cp3 += sprintf(CS cp3, "%.2x ", *cp1);
+cp3[-1]= '\0';
+
+return cp2;
+}
+
+uschar *
+tls_cert_subject_altname(void * cert, uschar * mod)
+{
+gstring * list = NULL;
+size_t siz;
+int ret;
+uschar sep = '\n';
+uschar * tag = US"";
+uschar * ele;
+int match = -1;
+
+while (mod)
+ {
+ if (*mod == '>' && *++mod) sep = *mod++;
+ else if (Ustrcmp(mod, "dns")==0) { match = GNUTLS_SAN_DNSNAME; mod += 3; }
+ else if (Ustrcmp(mod, "uri")==0) { match = GNUTLS_SAN_URI; mod += 3; }
+ else if (Ustrcmp(mod, "mail")==0) { match = GNUTLS_SAN_RFC822NAME; mod += 4; }
+ else continue;
+
+ if (*mod++ != ',')
+ break;
+ }
+
+for (int index = 0;; index++)
+ {
+ siz = 0;
+ switch(ret = gnutls_x509_crt_get_subject_alt_name(
+ (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL))
+ {
+ case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE:
+ return string_from_gstring(list); /* no more elements; normal exit */
+
+ case GNUTLS_E_SHORT_MEMORY_BUFFER:
+ break;
+
+ default:
+ return g_err("gs0", __FUNCTION__, ret);
+ }
+
+ ele = store_get(siz+1, TRUE);
+ if ((ret = gnutls_x509_crt_get_subject_alt_name(
+ (gnutls_x509_crt_t)cert, index, ele, &siz, NULL)) < 0)
+ return g_err("gs1", __FUNCTION__, ret);
+ ele[siz] = '\0';
+
+ if ( match != -1 && match != ret /* wrong type of SAN */
+ || Ustrlen(ele) != siz) /* contains a NUL */
+ continue;
+ switch (ret)
+ {
+ case GNUTLS_SAN_DNSNAME: tag = US"DNS"; break;
+ case GNUTLS_SAN_URI: tag = US"URI"; break;
+ case GNUTLS_SAN_RFC822NAME: tag = US"MAIL"; break;
+ default: continue; /* ignore unrecognised types */
+ }
+ list = string_append_listele(list, sep,
+ match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
+ }
+/*NOTREACHED*/
+}
+
+uschar *
+tls_cert_ocsp_uri(void * cert, uschar * mod)
+{
+#if GNUTLS_VERSION_NUMBER >= 0x030000
+gnutls_datum_t uri;
+int ret;
+uschar sep = '\n';
+gstring * list = NULL;
+
+if (mod)
+ if (*mod == '>' && *++mod) sep = *mod++;
+
+for (int index = 0;; index++)
+ {
+ ret = gnutls_x509_crt_get_authority_info_access((gnutls_x509_crt_t)cert,
+ index, GNUTLS_IA_OCSP_URI, &uri, NULL);
+
+ if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
+ return string_from_gstring(list);
+ if (ret < 0)
+ return g_err("gai", __FUNCTION__, ret);
+
+ list = string_append_listele_n(list, sep, uri.data, uri.size);
+ }
+/*NOTREACHED*/
+
+#else
+
+expand_string_message =
+ string_sprintf("%s: OCSP support with GnuTLS requires version 3.0.0\n",
+ __FUNCTION__);
+return NULL;
+
+#endif
+}
+
+uschar *
+tls_cert_crl_uri(void * cert, uschar * mod)
+{
+int ret;
+uschar sep = '\n';
+gstring * list = NULL;
+uschar * ele;
+
+if (mod)
+ if (*mod == '>' && *++mod) sep = *mod++;
+
+for (int index = 0;; index++)
+ {
+ size_t siz = 0;
+ switch(ret = gnutls_x509_crt_get_crl_dist_points(
+ (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL, NULL))
+ {
+ case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE:
+ return string_from_gstring(list);
+ case GNUTLS_E_SHORT_MEMORY_BUFFER:
+ break;
+ default:
+ return g_err("gc0", __FUNCTION__, ret);
+ }
+
+ ele = store_get(siz, TRUE);
+ if ((ret = gnutls_x509_crt_get_crl_dist_points(
+ (gnutls_x509_crt_t)cert, index, ele, &siz, NULL, NULL)) < 0)
+ return g_err("gc1", __FUNCTION__, ret);
+
+ list = string_append_listele_n(list, sep, ele, siz);
+ }
+/*NOTREACHED*/
+}
+
+
+/*****************************************************
+* Certificate operator routines
+*****************************************************/
+uschar *
+tls_cert_der_b64(void * cert)
+{
+size_t len = 0;
+uschar * cp = NULL;
+int fail;
+
+if ( (fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert,
+ GNUTLS_X509_FMT_DER, cp, &len)) != GNUTLS_E_SHORT_MEMORY_BUFFER
+ || !(cp = store_get((int)len, TRUE), TRUE) /* tainted */
+ || (fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert,
+ GNUTLS_X509_FMT_DER, cp, &len))
+ )
+ {
+ log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
+ gnutls_strerror(fail));
+ return NULL;
+ }
+return b64encode(CUS cp, (int)len);
+}
+
+
+static uschar *
+fingerprint(gnutls_x509_crt_t cert, gnutls_digest_algorithm_t algo)
+{
+int ret;
+size_t siz = 0;
+uschar * cp;
+uschar * cp2;
+
+if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, NULL, &siz))
+ != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return g_err("gf0", __FUNCTION__, ret);
+
+cp = store_get(siz*3+1, TRUE);
+if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, cp, &siz)) < 0)
+ return g_err("gf1", __FUNCTION__, ret);
+
+for (uschar * cp3 = cp2 = cp+siz; cp < cp2; cp++)
+ cp3 += sprintf(CS cp3, "%02X", *cp);
+return cp2;
+}
+
+
+uschar *
+tls_cert_fprt_md5(void * cert)
+{
+return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_MD5);
+}
+
+uschar *
+tls_cert_fprt_sha1(void * cert)
+{
+return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA1);
+}
+
+uschar *
+tls_cert_fprt_sha256(void * cert)
+{
+return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA256);
+}
+
+
+/* vi: aw ai sw=2
+*/
+/* End of tlscert-gnu.c */