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Diffstat (limited to 'src/tlscert-gnu.c')
| -rw-r--r-- | src/tlscert-gnu.c | 482 |
1 files changed, 482 insertions, 0 deletions
diff --git a/src/tlscert-gnu.c b/src/tlscert-gnu.c new file mode 100644 index 0000000..a40bb30 --- /dev/null +++ b/src/tlscert-gnu.c @@ -0,0 +1,482 @@ +/************************************************* +* Exim - an Internet mail transport agent * +*************************************************/ + +/* Copyright (c) The Exim Maintainers 2021 - 2022 */ +/* 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, GET_UNTAINTED); +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, GET_TAINTED); +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, GET_TAINTED); +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, GET_TAINTED); +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, GET_TAINTED); + +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; + +if (mod) while (*mod) + { + if (*mod == '>' && *++mod) sep = *mod++; + else if (Ustrncmp(mod, "dns", 3)==0) { match = GNUTLS_SAN_DNSNAME; mod += 3; } + else if (Ustrncmp(mod, "uri", 3)==0) { match = GNUTLS_SAN_URI; mod += 3; } + else if (Ustrncmp(mod, "mail", 4)==0) { match = GNUTLS_SAN_RFC822NAME; mod += 4; } + else break; + + 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, GET_TAINTED); + 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, GET_TAINTED); + 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, GET_TAINTED), 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, GET_TAINTED); +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 */ |