Gitweb:
http://git.exim.org/exim.git/commitdiff/e682570f275e60cf75f013c234a0561a451ab559
Commit: e682570f275e60cf75f013c234a0561a451ab559
Parent: 91664d8f02e873e8d39ef46ed0e65ea26cf11232
Author: Todd Lyons <tlyons@???>
AuthorDate: Wed Mar 5 06:17:54 2014 -0800
Committer: Todd Lyons <tlyons@???>
CommitDate: Tue Jul 29 05:53:50 2014 -0700
Framework to build dane support
---
doc/doc-txt/OptionLists.txt | 1 +
src/OS/Makefile-Base | 3 +-
src/scripts/MakeLinks | 4 +
src/src/config.h.defaults | 1 +
src/src/dane-gnu.c | 21 +
src/src/dane-openssl.c | 1306 +++++++++++++++++++++++++++++++++++++++++++
src/src/dane.c | 46 ++
src/src/danessl.h | 31 +
src/src/globals.c | 3 +
src/src/globals.h | 3 +
10 files changed, 1418 insertions(+), 1 deletions(-)
diff --git a/doc/doc-txt/OptionLists.txt b/doc/doc-txt/OptionLists.txt
index ef61956..375850d 100644
--- a/doc/doc-txt/OptionLists.txt
+++ b/doc/doc-txt/OptionLists.txt
@@ -181,6 +181,7 @@ dns_check_names_pattern string + main
dns_csa_search_limit integer 5 main 4.60
dns_csa_use_reverse boolean true main 4.60
dns_dnssec_ok integer -1 main 4.82
+dns_dane_ok integer -1 main 4.83
dns_ipv4_lookup boolean false main 3.20
dns_qualify_single boolean true smtp
dns_retrans time 0s main 1.60
diff --git a/src/OS/Makefile-Base b/src/OS/Makefile-Base
index 87a8037..8937f3c 100644
--- a/src/OS/Makefile-Base
+++ b/src/OS/Makefile-Base
@@ -298,7 +298,7 @@ convert4r4: Makefile ../src/convert4r4.src
OBJ_WITH_CONTENT_SCAN = malware.o mime.o regex.o spam.o spool_mbox.o
OBJ_WITH_OLD_DEMIME = demime.o
-OBJ_EXPERIMENTAL = bmi_spam.o spf.o srs.o dcc.o dmarc.o
+OBJ_EXPERIMENTAL = bmi_spam.o spf.o srs.o dcc.o dmarc.o dane.o
# Targets for final binaries; the main one has a build number which is
# updated each time. We don't bother with that for the auxiliaries.
@@ -541,6 +541,7 @@ acl.o: $(HDRS) acl.c
child.o: $(HDRS) child.c
crypt16.o: $(HDRS) crypt16.c
daemon.o: $(HDRS) daemon.c
+dane.o: $(HDRS) dane.c dane-gnu.c dane-openssl.c
dbfn.o: $(HDRS) dbfn.c
debug.o: $(HDRS) debug.c
deliver.o: $(HDRS) deliver.c
diff --git a/src/scripts/MakeLinks b/src/scripts/MakeLinks
index 01cd21f..a50f75b 100755
--- a/src/scripts/MakeLinks
+++ b/src/scripts/MakeLinks
@@ -271,6 +271,10 @@ ln -s ../src/srs.c srs.c
ln -s ../src/srs.h srs.h
ln -s ../src/dcc.c dcc.c
ln -s ../src/dcc.h dcc.h
+ln -s ../src/dane.c dane.c
+ln -s ../src/dane-gnu.c dane-gnu.c
+ln -s ../src/dane-openssl.c dane-openssl.c
+ln -s ../src/danessl.h danessl.h
# End of MakeLinks
diff --git a/src/src/config.h.defaults b/src/src/config.h.defaults
index ba4615c..49ab276 100644
--- a/src/src/config.h.defaults
+++ b/src/src/config.h.defaults
@@ -168,6 +168,7 @@ it's a default value. */
/* EXPERIMENTAL features */
#define EXPERIMENTAL_BRIGHTMAIL
#define EXPERIMENTAL_CERTNAMES
+#define EXPERIMENTAL_DANE
#define EXPERIMENTAL_DCC
#define EXPERIMENTAL_DMARC
#define EXPERIMENTAL_DSN
diff --git a/src/src/dane-gnu.c b/src/src/dane-gnu.c
new file mode 100644
index 0000000..b98bffa
--- /dev/null
+++ b/src/src/dane-gnu.c
@@ -0,0 +1,21 @@
+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2013 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file (will) provide DANE support for Exim using the GnuTLS library,
+but is not yet an available supported implementation. This file is #included
+into dane.c when USE_GNUTLS has been set. */
+
+/* As of March 2014, the reference implementation for DANE that we are
+using was written by Viktor Dukhovny and it supports OpenSSL only. At
+some point we will add GnuTLS support, but for right now just abort the
+build and explain why. */
+
+
+#error No support for DANE using GnuTLS yet.
+
+
+/* End of dane-gnu.c */
diff --git a/src/src/dane-openssl.c b/src/src/dane-openssl.c
new file mode 100644
index 0000000..790b4f0
--- /dev/null
+++ b/src/src/dane-openssl.c
@@ -0,0 +1,1306 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+
+#include <openssl/opensslv.h>
+#include <openssl/err.h>
+#include <openssl/crypto.h>
+#include <openssl/safestack.h>
+#include <openssl/objects.h>
+#include <openssl/x509.h>
+#include <openssl/x509v3.h>
+#include <openssl/evp.h>
+
+#if OPENSSL_VERSION_NUMBER < 0x1000000fL
+#error "OpenSSL 1.0.0 or higher required"
+#else
+
+#include "danessl.h"
+
+#define DANE_F_ADD_SKID 100
+#define DANE_F_CHECK_END_ENTITY 101
+#define DANE_F_GROW_CHAIN 102
+#define DANE_F_LIST_ALLOC 103
+#define DANE_F_MATCH 104
+#define DANE_F_PUSH_EXT 105
+#define DANE_F_SET_TRUST_ANCHOR 106
+#define DANE_F_SSL_CTX_DANE_INIT 107
+#define DANE_F_SSL_DANE_ADD_TLSA 108
+#define DANE_F_SSL_DANE_INIT 109
+#define DANE_F_SSL_DANE_LIBRARY_INIT 110
+#define DANE_F_VERIFY_CERT 111
+#define DANE_F_WRAP_CERT 112
+
+#define DANE_R_BAD_CERT 100
+#define DANE_R_BAD_CERT_PKEY 101
+#define DANE_R_BAD_DATA_LENGTH 102
+#define DANE_R_BAD_DIGEST 103
+#define DANE_R_BAD_NULL_DATA 104
+#define DANE_R_BAD_PKEY 105
+#define DANE_R_BAD_SELECTOR 106
+#define DANE_R_BAD_USAGE 107
+#define DANE_R_DANE_INIT 108
+#define DANE_R_DANE_SUPPORT 109
+#define DANE_R_LIBRARY_INIT 110
+#define DANE_R_NOSIGN_KEY 111
+#define DANE_R_SCTX_INIT 112
+
+#ifndef OPENSSL_NO_ERR
+#define DANE_F_PLACEHOLDER 0 /* FIRST! Value TBD */
+static ERR_STRING_DATA dane_str_functs[] = {
+ {DANE_F_PLACEHOLDER, "DANE library"}, /* FIRST!!! */
+ {DANE_F_ADD_SKID, "add_skid"},
+ {DANE_F_CHECK_END_ENTITY, "check_end_entity"},
+ {DANE_F_GROW_CHAIN, "grow_chain"},
+ {DANE_F_LIST_ALLOC, "list_alloc"},
+ {DANE_F_MATCH, "match"},
+ {DANE_F_PUSH_EXT, "push_ext"},
+ {DANE_F_SET_TRUST_ANCHOR, "set_trust_anchor"},
+ {DANE_F_SSL_CTX_DANE_INIT, "SSL_CTX_dane_init"},
+ {DANE_F_SSL_DANE_ADD_TLSA, "SSL_dane_add_tlsa"},
+ {DANE_F_SSL_DANE_INIT, "SSL_dane_init"},
+ {DANE_F_SSL_DANE_LIBRARY_INIT, "SSL_dane_library_init"},
+ {DANE_F_VERIFY_CERT, "verify_cert"},
+ {DANE_F_WRAP_CERT, "wrap_cert"},
+ {0, NULL}
+};
+static ERR_STRING_DATA dane_str_reasons[] = {
+ {DANE_R_BAD_CERT, "Bad TLSA record certificate"},
+ {DANE_R_BAD_CERT_PKEY, "Bad TLSA record certificate public key"},
+ {DANE_R_BAD_DATA_LENGTH, "Bad TLSA record digest length"},
+ {DANE_R_BAD_DIGEST, "Bad TLSA record digest"},
+ {DANE_R_BAD_NULL_DATA, "Bad TLSA record null data"},
+ {DANE_R_BAD_PKEY, "Bad TLSA record public key"},
+ {DANE_R_BAD_SELECTOR, "Bad TLSA record selector"},
+ {DANE_R_BAD_USAGE, "Bad TLSA record usage"},
+ {DANE_R_DANE_INIT, "SSL_dane_init() required"},
+ {DANE_R_DANE_SUPPORT, "DANE library features not supported"},
+ {DANE_R_LIBRARY_INIT, "SSL_dane_library_init() required"},
+ {DANE_R_SCTX_INIT, "SSL_CTX_dane_init() required"},
+ {DANE_R_NOSIGN_KEY, "Certificate usage 2 requires EC support"},
+ {0, NULL}
+};
+#endif
+
+#define DANEerr(f, r) ERR_PUT_error(err_lib_dane, (f), (r), __FILE__, __LINE__)
+
+static int err_lib_dane = -1;
+static int dane_idx = -1;
+
+#ifdef X509_V_FLAG_PARTIAL_CHAIN /* OpenSSL >= 1.0.2 */
+static int wrap_to_root = 0;
+#else
+static int wrap_to_root = 1;
+#endif
+
+static void (*cert_free)(void *) = (void (*)(void *)) X509_free;
+static void (*pkey_free)(void *) = (void (*)(void *)) EVP_PKEY_free;
+
+typedef struct dane_list {
+ struct dane_list *next;
+ void *value;
+} *dane_list;
+
+#define LINSERT(h, e) do { (e)->next = (h); (h) = (e); } while (0)
+
+typedef struct DANE_HOST_LIST {
+ struct DANE_HOST_LIST *next;
+ char *value;
+} *DANE_HOST_LIST;
+
+typedef struct dane_data {
+ size_t datalen;
+ unsigned char data[0];
+} *dane_data;
+
+typedef struct DANE_DATA_LIST {
+ struct DANE_DATA_LIST *next;
+ dane_data value;
+} *DANE_DATA_LIST;
+
+typedef struct dane_mtype {
+ int mdlen;
+ const EVP_MD *md;
+ DANE_DATA_LIST data;
+} *dane_mtype;
+
+typedef struct DANE_MTYPE_LIST {
+ struct DANE_MTYPE_LIST *next;
+ dane_mtype value;
+} *DANE_MTYPE_LIST;
+
+typedef struct dane_selector {
+ uint8_t selector;
+ DANE_MTYPE_LIST mtype;
+} *dane_selector;
+
+typedef struct DANE_SELECTOR_LIST {
+ struct DANE_SELECTOR_LIST *next;
+ dane_selector value;
+} *DANE_SELECTOR_LIST;
+
+typedef struct DANE_PKEY_LIST {
+ struct DANE_PKEY_LIST *next;
+ EVP_PKEY *value;
+} *DANE_PKEY_LIST;
+
+typedef struct DANE_CERT_LIST {
+ struct DANE_CERT_LIST *next;
+ X509 *value;
+} *DANE_CERT_LIST;
+
+typedef struct SSL_DANE {
+ int (*verify)(X509_STORE_CTX *);
+ STACK_OF(X509) *roots;
+ STACK_OF(X509) *chain;
+ const char *thost; /* TLSA base domain */
+ char *mhost; /* Matched, peer name */
+ DANE_PKEY_LIST pkeys;
+ DANE_CERT_LIST certs;
+ DANE_HOST_LIST hosts;
+ DANE_SELECTOR_LIST selectors[SSL_DANE_USAGE_LAST + 1];
+ int depth;
+ int multi; /* Multi-label wildcards? */
+ int count; /* Number of TLSA records */
+} SSL_DANE;
+
+#ifndef X509_V_ERR_HOSTNAME_MISMATCH
+#define X509_V_ERR_HOSTNAME_MISMATCH X509_V_ERR_APPLICATION_VERIFICATION
+#endif
+
+static int match(DANE_SELECTOR_LIST slist, X509 *cert, int depth)
+{
+ int matched;
+
+ /*
+ * Note, set_trust_anchor() needs to know whether the match was for a
+ * pkey digest or a certificate digest. We return MATCHED_PKEY or
+ * MATCHED_CERT accordingly.
+ */
+#define MATCHED_CERT (SSL_DANE_SELECTOR_CERT + 1)
+#define MATCHED_PKEY (SSL_DANE_SELECTOR_SPKI + 1)
+
+ /*
+ * Loop over each selector, mtype, and associated data element looking
+ * for a match.
+ */
+ for (matched = 0; !matched && slist; slist = slist->next) {
+ DANE_MTYPE_LIST m;
+ unsigned char mdbuf[EVP_MAX_MD_SIZE];
+ unsigned char *buf;
+ unsigned char *buf2;
+ unsigned int len;
+
+ /*
+ * Extract ASN.1 DER form of certificate or public key.
+ */
+ switch (slist->value->selector) {
+ case SSL_DANE_SELECTOR_CERT:
+ len = i2d_X509(cert, NULL);
+ buf2 = buf = (unsigned char *) OPENSSL_malloc(len);
+ if (buf)
+ i2d_X509(cert, &buf2);
+ break;
+ case SSL_DANE_SELECTOR_SPKI:
+ len = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), NULL);
+ buf2 = buf = (unsigned char *) OPENSSL_malloc(len);
+ if (buf)
+ i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), &buf2);
+ break;
+ }
+
+ if (buf == NULL) {
+ DANEerr(DANE_F_MATCH, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ OPENSSL_assert(buf2 - buf == len);
+
+ /*
+ * Loop over each mtype and data element
+ */
+ for (m = slist->value->mtype; !matched && m; m = m->next) {
+ DANE_DATA_LIST d;
+ unsigned char *cmpbuf = buf;
+ unsigned int cmplen = len;
+
+ /*
+ * If it is a digest, compute the corresponding digest of the
+ * DER data for comparison, otherwise, use the full object.
+ */
+ if (m->value->md) {
+ cmpbuf = mdbuf;
+ if (!EVP_Digest(buf, len, cmpbuf, &cmplen, m->value->md, 0))
+ matched = -1;
+ }
+ for (d = m->value->data; !matched && d; d = d->next)
+ if (cmplen == d->value->datalen &&
+ memcmp(cmpbuf, d->value->data, cmplen) == 0)
+ matched = slist->value->selector + 1;
+ }
+
+ OPENSSL_free(buf);
+ }
+
+ return matched;
+}
+
+static int push_ext(X509 *cert, X509_EXTENSION *ext)
+{
+ X509_EXTENSIONS *exts;
+
+ if (ext) {
+ if ((exts = cert->cert_info->extensions) == 0)
+ exts = cert->cert_info->extensions = sk_X509_EXTENSION_new_null();
+ if (exts && sk_X509_EXTENSION_push(exts, ext))
+ return 1;
+ X509_EXTENSION_free(ext);
+ }
+ DANEerr(DANE_F_PUSH_EXT, ERR_R_MALLOC_FAILURE);
+ return 0;
+}
+
+static int add_ext(X509 *issuer, X509 *subject, int ext_nid, char *ext_val)
+{
+ X509V3_CTX v3ctx;
+
+ X509V3_set_ctx(&v3ctx, issuer, subject, 0, 0, 0);
+ return push_ext(subject, X509V3_EXT_conf_nid(0, &v3ctx, ext_nid, ext_val));
+}
+
+static int set_serial(X509 *cert, AUTHORITY_KEYID *akid, X509 *subject)
+{
+ int ret = 0;
+ BIGNUM *bn;
+
+ if (akid && akid->serial)
+ return (X509_set_serialNumber(cert, akid->serial));
+
+ /*
+ * Add one to subject's serial to avoid collisions between TA serial and
+ * serial of signing root.
+ */
+ if ((bn = ASN1_INTEGER_to_BN(X509_get_serialNumber(subject), 0)) != 0
+ && BN_add_word(bn, 1)
+ && BN_to_ASN1_INTEGER(bn, X509_get_serialNumber(cert)))
+ ret = 1;
+
+ if (bn)
+ BN_free(bn);
+ return ret;
+}
+
+static int add_akid(X509 *cert, AUTHORITY_KEYID *akid)
+{
+ int nid = NID_authority_key_identifier;
+ ASN1_STRING *id;
+ unsigned char c = 0;
+ int ret = 0;
+
+ /*
+ * 0 will never be our subject keyid from a SHA-1 hash, but it could be
+ * our subject keyid if forced from child's akid. If so, set our
+ * authority keyid to 1. This way we are never self-signed, and thus
+ * exempt from any potential (off by default for now in OpenSSL)
+ * self-signature checks!
+ */
+ id = (ASN1_STRING *) ((akid && akid->keyid) ? akid->keyid : 0);
+ if (id && M_ASN1_STRING_length(id) == 1 && *M_ASN1_STRING_data(id) == c)
+ c = 1;
+
+ if ((akid = AUTHORITY_KEYID_new()) != 0
+ && (akid->keyid = ASN1_OCTET_STRING_new()) != 0
+ && M_ASN1_OCTET_STRING_set(akid->keyid, (void *) &c, 1)
+ && X509_add1_ext_i2d(cert, nid, akid, 0, X509V3_ADD_APPEND))
+ ret = 1;
+ if (akid)
+ AUTHORITY_KEYID_free(akid);
+ return ret;
+}
+
+static int add_skid(X509 *cert, AUTHORITY_KEYID *akid)
+{
+ int nid = NID_subject_key_identifier;
+
+ if (!akid || !akid->keyid)
+ return add_ext(0, cert, nid, "hash");
+ return X509_add1_ext_i2d(cert, nid, akid->keyid, 0, X509V3_ADD_APPEND) > 0;
+}
+
+static X509_NAME *akid_issuer_name(AUTHORITY_KEYID *akid)
+{
+ if (akid && akid->issuer) {
+ int i;
+ GENERAL_NAMES *gens = akid->issuer;
+
+ for (i = 0; i < sk_GENERAL_NAME_num(gens); ++i) {
+ GENERAL_NAME *gn = sk_GENERAL_NAME_value(gens, i);
+
+ if (gn->type == GEN_DIRNAME)
+ return (gn->d.dirn);
+ }
+ }
+ return 0;
+}
+
+static int set_issuer_name(X509 *cert, AUTHORITY_KEYID *akid)
+{
+ X509_NAME *name = akid_issuer_name(akid);
+
+ /*
+ * If subject's akid specifies an authority key identifer issuer name, we
+ * must use that.
+ */
+ if (name)
+ return X509_set_issuer_name(cert, name);
+ return X509_set_issuer_name(cert, X509_get_subject_name(cert));
+}
+
+static int grow_chain(SSL_DANE *dane, int trusted, X509 *cert)
+{
+ STACK_OF(X509) **xs = trusted ? &dane->roots : &dane->chain;
+ static ASN1_OBJECT *serverAuth = 0;
+
+#define UNTRUSTED 0
+#define TRUSTED 1
+
+ if (trusted && serverAuth == 0 &&
+ (serverAuth = OBJ_nid2obj(NID_server_auth)) == 0) {
+ DANEerr(DANE_F_GROW_CHAIN, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ if (!*xs && (*xs = sk_X509_new_null()) == 0) {
+ DANEerr(DANE_F_GROW_CHAIN, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+
+ if (cert) {
+ if (trusted && !X509_add1_trust_object(cert, serverAuth))
+ return 0;
+ CRYPTO_add(&cert->references, 1, CRYPTO_LOCK_X509);
+ if (!sk_X509_push(*xs, cert)) {
+ X509_free(cert);
+ DANEerr(DANE_F_GROW_CHAIN, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ }
+ return 1;
+}
+
+static int wrap_issuer(
+ SSL_DANE *dane,
+ EVP_PKEY *key,
+ X509 *subject,
+ int depth,
+ int top
+)
+{
+ int ret = 1;
+ X509 *cert = 0;
+ AUTHORITY_KEYID *akid;
+ X509_NAME *name = X509_get_issuer_name(subject);
+ EVP_PKEY *newkey = key ? key : X509_get_pubkey(subject);
+
+#define WRAP_MID 0 /* Ensure intermediate. */
+#define WRAP_TOP 1 /* Ensure self-signed. */
+
+ if (name == 0 || newkey == 0 || (cert = X509_new()) == 0)
+ return 0;
+
+ /*
+ * Record the depth of the trust-anchor certificate.
+ */
+ if (dane->depth < 0)
+ dane->depth = depth + 1;
+
+ /*
+ * XXX: Uncaught error condition:
+ *
+ * The return value is NULL both when the extension is missing, and when
+ * OpenSSL rans out of memory while parsing the extension.
+ */
+ ERR_clear_error();
+ akid = X509_get_ext_d2i(subject, NID_authority_key_identifier, 0, 0);
+ /* XXX: Should we peek at the error stack here??? */
+
+ /*
+ * If top is true generate a self-issued root CA, otherwise an
+ * intermediate CA and possibly its self-signed issuer.
+ *
+ * CA cert valid for +/- 30 days
+ */
+ if (!X509_set_version(cert, 2)
+ || !set_serial(cert, akid, subject)
+ || !X509_set_subject_name(cert, name)
+ || !set_issuer_name(cert, akid)
+ || !X509_gmtime_adj(X509_get_notBefore(cert), -30 * 86400L)
+ || !X509_gmtime_adj(X509_get_notAfter(cert), 30 * 86400L)
+ || !X509_set_pubkey(cert, newkey)
+ || !add_ext(0, cert, NID_basic_constraints, "CA:TRUE")
+ || (!top && !add_akid(cert, akid))
+ || !add_skid(cert, akid)
+ || (!top && wrap_to_root &&
+ !wrap_issuer(dane, newkey, cert, depth, WRAP_TOP))) {
+ ret = 0;
+ }
+ if (akid)
+ AUTHORITY_KEYID_free(akid);
+ if (!key)
+ EVP_PKEY_free(newkey);
+ if (ret) {
+ if (!top && wrap_to_root)
+ ret = grow_chain(dane, UNTRUSTED, cert);
+ else
+ ret = grow_chain(dane, TRUSTED, cert);
+ }
+ if (cert)
+ X509_free(cert);
+ return ret;
+}
+
+static int wrap_cert(SSL_DANE *dane, X509 *tacert, int depth)
+{
+ if (dane->depth < 0)
+ dane->depth = depth + 1;
+
+ /*
+ * If the TA certificate is self-issued, or need not be, use it directly.
+ * Otherwise, synthesize requisuite ancestors.
+ */
+ if (!wrap_to_root
+ || X509_check_issued(tacert, tacert) == X509_V_OK)
+ return grow_chain(dane, TRUSTED, tacert);
+
+ if (wrap_issuer(dane, 0, tacert, depth, WRAP_MID))
+ return grow_chain(dane, UNTRUSTED, tacert);
+ return 0;
+}
+
+static int ta_signed(SSL_DANE *dane, X509 *cert, int depth)
+{
+ DANE_CERT_LIST x;
+ DANE_PKEY_LIST k;
+ EVP_PKEY *pk;
+ int done = 0;
+
+ /*
+ * First check whether issued and signed by a TA cert, this is cheaper
+ * than the bare-public key checks below, since we can determine whether
+ * the candidate TA certificate issued the certificate to be checked
+ * first (name comparisons), before we bother with signature checks
+ * (public key operations).
+ */
+ for (x = dane->certs; !done && x; x = x->next) {
+ if (X509_check_issued(x->value, cert) == X509_V_OK) {
+ if ((pk = X509_get_pubkey(x->value)) == 0) {
+ /*
+ * The cert originally contained a valid pkey, which does
+ * not just vanish, so this is most likely a memory error.
+ */
+ done = -1;
+ break;
+ }
+ /* Check signature, since some other TA may work if not this. */
+ if (X509_verify(cert, pk) > 0)
+ done = wrap_cert(dane, x->value, depth) ? 1 : -1;
+ EVP_PKEY_free(pk);
+ }
+ }
+
+ /*
+ * With bare TA public keys, we can't check whether the trust chain is
+ * issued by the key, but we can determine whether it is signed by the
+ * key, so we go with that.
+ *
+ * Ideally, the corresponding certificate was presented in the chain, and we
+ * matched it by its public key digest one level up. This code is here
+ * to handle adverse conditions imposed by sloppy administrators of
+ * receiving systems with poorly constructed chains.
+ *
+ * We'd like to optimize out keys that should not match when the cert's
+ * authority key id does not match the key id of this key computed via
+ * the RFC keyid algorithm (SHA-1 digest of public key bit-string sans
+ * ASN1 tag and length thus also excluding the unused bits field that is
+ * logically part of the length). However, some CAs have a non-standard
+ * authority keyid, so we lose. Too bad.
+ *
+ * This may push errors onto the stack when the certificate signature is
+ * not of the right type or length, throw these away,
+ */
+ for (k = dane->pkeys; !done && k; k = k->next)
+ if (X509_verify(cert, k->value) > 0)
+ done = wrap_issuer(dane, k->value, cert, depth, WRAP_MID) ? 1 : -1;
+ else
+ ERR_clear_error();
+
+ return done;
+}
+
+static int set_trust_anchor(X509_STORE_CTX *ctx, SSL_DANE *dane, X509 *cert)
+{
+ int matched = 0;
+ int n;
+ int i;
+ int depth = 0;
+ EVP_PKEY *takey;
+ X509 *ca;
+ STACK_OF(X509) *in = ctx->untrusted; /* XXX: Accessor? */
+
+ if (!grow_chain(dane, UNTRUSTED, 0))
+ return -1;
+
+ /*
+ * Accept a degenerate case: depth 0 self-signed trust-anchor.
+ */
+ if (X509_check_issued(cert, cert) == X509_V_OK) {
+ dane->depth = 0;
+ matched = match(dane->selectors[SSL_DANE_USAGE_TRUSTED_CA], cert, 0);
+ if (matched > 0 && !grow_chain(dane, TRUSTED, cert))
+ matched = -1;
+ return matched;
+ }
+
+ /* Make a shallow copy of the input untrusted chain. */
+ if ((in = sk_X509_dup(in)) == 0) {
+ DANEerr(DANE_F_SET_TRUST_ANCHOR, ERR_R_MALLOC_FAILURE);
+ return -1;
+ }
+
+ /*
+ * At each iteration we consume the issuer of the current cert. This
+ * reduces the length of the "in" chain by one. If no issuer is found,
+ * we are done. We also stop when a certificate matches a TA in the
+ * peer's TLSA RRset.
+ *
+ * Caller ensures that the initial certificate is not self-signed.
+ */
+ for (n = sk_X509_num(in); n > 0; --n, ++depth) {
+ for (i = 0; i < n; ++i)
+ if (X509_check_issued(sk_X509_value(in, i), cert) == X509_V_OK)
+ break;
+
+ /*
+ * Final untrusted element with no issuer in the peer's chain, it may
+ * however be signed by a pkey or cert obtained via a TLSA RR.
+ */
+ if (i == n)
+ break;
+
+ /* Peer's chain contains an issuer ca. */
+ ca = sk_X509_delete(in, i);
+
+ /* If not a trust anchor, record untrusted ca and continue. */
+ if ((matched = match(dane->selectors[SSL_DANE_USAGE_TRUSTED_CA], ca,
+ depth + 1)) == 0) {
+ if (grow_chain(dane, UNTRUSTED, ca)) {
+ if (!X509_check_issued(ca, ca) == X509_V_OK) {
+ /* Restart with issuer as subject */
+ cert = ca;
+ continue;
+ }
+ /* Final self-signed element, skip ta_signed() check. */
+ cert = 0;
+ } else
+ matched = -1;
+ } else if (matched == MATCHED_CERT) {
+ if (!wrap_cert(dane, ca, depth))
+ matched = -1;
+ } else if (matched == MATCHED_PKEY) {
+ if ((takey = X509_get_pubkey(ca)) == 0 ||
+ !wrap_issuer(dane, takey, cert, depth, WRAP_MID)) {
+ if (takey)
+ EVP_PKEY_free(takey);
+ else
+ DANEerr(DANE_F_SET_TRUST_ANCHOR, ERR_R_MALLOC_FAILURE);
+ matched = -1;
+ }
+ }
+ break;
+ }
+
+ /* Shallow free the duplicated input untrusted chain. */
+ sk_X509_free(in);
+
+ /*
+ * When the loop exits, if "cert" is set, it is not self-signed and has
+ * no issuer in the chain, we check for a possible signature via a DNS
+ * obtained TA cert or public key.
+ */
+ if (matched == 0 && cert)
+ matched = ta_signed(dane, cert, depth);
+
+ return matched;
+}
+
+static int check_end_entity(X509_STORE_CTX *ctx, SSL_DANE *dane, X509 *cert)
+{
+ int matched;
+
+ matched = match(dane->selectors[SSL_DANE_USAGE_FIXED_LEAF], cert, 0);
+ if (matched > 0) {
+ if (ctx->chain == 0) {
+ if ((ctx->chain = sk_X509_new_null()) != 0 &&
+ sk_X509_push(ctx->chain, cert)) {
+ CRYPTO_add(&cert->references, 1, CRYPTO_LOCK_X509);
+ } else {
+ DANEerr(DANE_F_CHECK_END_ENTITY, ERR_R_MALLOC_FAILURE);
+ return -1;
+ }
+ }
+ }
+ return matched;
+}
+
+static int match_name(const char *certid, SSL_DANE *dane)
+{
+ int multi = dane->multi;
+ DANE_HOST_LIST hosts = dane->hosts;
+
+ for (/* NOP */; hosts; hosts = hosts->next) {
+ int match_subdomain = 0;
+ const char *domain = hosts->value;
+ const char *parent;
+ int idlen;
+ int domlen;
+
+ if (*domain == '.' && domain[1] != '\0') {
+ ++domain;
+ match_subdomain = 1;
+ }
+
+ /*
+ * Sub-domain match: certid is any sub-domain of hostname.
+ */
+ if (match_subdomain) {
+ if ((idlen = strlen(certid)) > (domlen = strlen(domain)) + 1
+ && certid[idlen - domlen - 1] == '.'
+ && !strcasecmp(certid + (idlen - domlen), domain))
+ return 1;
+ else
+ continue;
+ }
+
+ /*
+ * Exact match and initial "*" match. The initial "*" in a certid
+ * matches one (if multi is false) or more hostname components under
+ * the condition that the certid contains multiple hostname components.
+ */
+ if (!strcasecmp(certid, domain)
+ || (certid[0] == '*' && certid[1] == '.' && certid[2] != 0
+ && (parent = strchr(domain, '.')) != 0
+ && (idlen = strlen(certid + 1)) <= (domlen = strlen(parent))
+ && strcasecmp(multi ? parent + domlen - idlen : parent,
+ certid + 1) == 0))
+ return 1;
+ }
+ return 0;
+}
+
+static char *check_name(char *name, int len)
+{
+ register char *cp = name + len;
+
+ while (len > 0 && *--cp == 0)
+ --len; /* Ignore trailing NULs */
+ if (len <= 0)
+ return 0;
+ for (cp = name; *cp; cp++) {
+ register char c = *cp;
+ if (!((c >= 'a' && c <= 'z') ||
+ (c >= '0' && c <= '9') ||
+ (c >= 'A' && c <= 'Z') ||
+ (c == '.' || c == '-') ||
+ (c == '*')))
+ return 0; /* Only LDH, '.' and '*' */
+ }
+ if (cp - name != len) /* Guard against internal NULs */
+ return 0;
+ return name;
+}
+
+static char *parse_dns_name(const GENERAL_NAME *gn)
+{
+ if (gn->type != GEN_DNS)
+ return 0;
+ if (ASN1_STRING_type(gn->d.ia5) != V_ASN1_IA5STRING)
+ return 0;
+ return check_name((char *) ASN1_STRING_data(gn->d.ia5),
+ ASN1_STRING_length(gn->d.ia5));
+}
+
+static char *parse_subject_name(X509 *cert)
+{
+ X509_NAME *name = X509_get_subject_name(cert);
+ X509_NAME_ENTRY *entry;
+ ASN1_STRING *entry_str;
+ unsigned char *namebuf;
+ int nid = NID_commonName;
+ int len;
+ int i;
+
+ if (name == 0 || (i = X509_NAME_get_index_by_NID(name, nid, -1)) < 0)
+ return 0;
+ if ((entry = X509_NAME_get_entry(name, i)) == 0)
+ return 0;
+ if ((entry_str = X509_NAME_ENTRY_get_data(entry)) == 0)
+ return 0;
+
+ if ((len = ASN1_STRING_to_UTF8(&namebuf, entry_str)) < 0)
+ return 0;
+ if (len <= 0 || check_name((char *) namebuf, len) == 0) {
+ OPENSSL_free(namebuf);
+ return 0;
+ }
+ return (char *) namebuf;
+}
+
+static int name_check(SSL_DANE *dane, X509 *cert)
+{
+ int matched = 0;
+ int got_altname = 0;
+ GENERAL_NAMES *gens;
+
+ gens = X509_get_ext_d2i(cert, NID_subject_alt_name, 0, 0);
+ if (gens) {
+ int n = sk_GENERAL_NAME_num(gens);
+ int i;
+
+ for (i = 0; i < n; ++i) {
+ const GENERAL_NAME *gn = sk_GENERAL_NAME_value(gens, i);
+ const char *certid;
+
+ if (gn->type != GEN_DNS)
+ continue;
+ got_altname = 1;
+ certid = parse_dns_name(gn);
+ if (certid && *certid) {
+ if ((matched = match_name(certid, dane)) == 0)
+ continue;
+ if ((dane->mhost = OPENSSL_strdup(certid)) == 0)
+ matched = -1;
+ break;
+ }
+ }
+ GENERAL_NAMES_free(gens);
+ }
+
+ /*
+ * XXX: Should the subjectName be skipped when *any* altnames are present,
+ * or only when DNS altnames are present?
+ */
+ if (got_altname == 0) {
+ char *certid = parse_subject_name(cert);
+ if (certid != 0 && *certid && (matched = match_name(certid, dane)) != 0)
+ dane->mhost = certid; /* Already a copy */
+ }
+ return matched;
+}
+
+static int verify_chain(X509_STORE_CTX *ctx)
+{
+ DANE_SELECTOR_LIST issuer_rrs;
+ DANE_SELECTOR_LIST leaf_rrs;
+ int (*cb)(int, X509_STORE_CTX *) = ctx->verify_cb;
+ int ssl_idx = SSL_get_ex_data_X509_STORE_CTX_idx();
+ SSL *ssl = X509_STORE_CTX_get_ex_data(ctx, ssl_idx);
+ SSL_DANE *dane = SSL_get_ex_data(ssl, dane_idx);
+ X509 *cert = ctx->cert; /* XXX: accessor? */
+ int matched = 0;
+ int chain_length = sk_X509_num(ctx->chain);
+
+ issuer_rrs = dane->selectors[SSL_DANE_USAGE_LIMIT_ISSUER];
+ leaf_rrs = dane->selectors[SSL_DANE_USAGE_LIMIT_LEAF];
+ ctx->verify = dane->verify;
+
+ if ((matched = name_check(dane, cert)) < 0) {
+ X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
+ return 0;
+ }
+
+ if (!matched) {
+ ctx->error_depth = 0;
+ ctx->current_cert = cert;
+ X509_STORE_CTX_set_error(ctx, X509_V_ERR_HOSTNAME_MISMATCH);
+ if (!cb(0, ctx))
+ return 0;
+ }
+ matched = 0;
+
+ /*
+ * Satisfy at least one usage 0 or 1 constraint, unless we've already
+ * matched a usage 2 trust anchor.
+ *
+ * XXX: internal_verify() doesn't callback with top certs that are not
+ * self-issued. This should be fixed in a future OpenSSL.
+ */
+ if (dane->roots && sk_X509_num(dane->roots)) {
+#ifndef NO_CALLBACK_WORKAROUND
+ X509 *top = sk_X509_value(ctx->chain, dane->depth);
+
+ if (X509_check_issued(top, top) != X509_V_OK) {
+ ctx->error_depth = dane->depth;
+ ctx->current_cert = top;
+ if (!cb(1, ctx))
+ return 0;
+ }
+#endif
+ /* Pop synthetic trust-anchor ancestors off the chain! */
+ while (--chain_length > dane->depth)
+ X509_free(sk_X509_pop(ctx->chain));
+ } else if (issuer_rrs || leaf_rrs) {
+ int n = chain_length;
+
+ /*
+ * Check for an EE match, then a CA match at depths > 0, and
+ * finally, if the EE cert is self-issued, for a depth 0 CA match.
+ */
+ if (leaf_rrs)
+ matched = match(leaf_rrs, cert, 0);
+ while (!matched && issuer_rrs && --n >= 0) {
+ X509 *xn = sk_X509_value(ctx->chain, n);
+
+ if (n > 0 || X509_check_issued(xn, xn) == X509_V_OK)
+ matched = match(issuer_rrs, xn, n);
+ }
+
+ if (matched < 0) {
+ X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
+ return 0;
+ }
+
+ if (!matched) {
+ ctx->current_cert = cert;
+ ctx->error_depth = 0;
+ X509_STORE_CTX_set_error(ctx, X509_V_ERR_CERT_UNTRUSTED);
+ if (!cb(0, ctx))
+ return 0;
+ }
+ }
+
+ return ctx->verify(ctx);
+}
+
+static int verify_cert(X509_STORE_CTX *ctx, void *unused_ctx)
+{
+ static int ssl_idx = -1;
+ SSL *ssl;
+ SSL_DANE *dane;
+ int (*cb)(int, X509_STORE_CTX *) = ctx->verify_cb;
+ int matched;
+ X509 *cert = ctx->cert; /* XXX: accessor? */
+
+ if (ssl_idx < 0)
+ ssl_idx = SSL_get_ex_data_X509_STORE_CTX_idx();
+ if (dane_idx < 0) {
+ DANEerr(DANE_F_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
+ return -1;
+ }
+
+ ssl = X509_STORE_CTX_get_ex_data(ctx, ssl_idx);
+ if ((dane = SSL_get_ex_data(ssl, dane_idx)) == 0 || cert == 0)
+ return X509_verify_cert(ctx);
+
+ if (dane->selectors[SSL_DANE_USAGE_FIXED_LEAF]) {
+ if ((matched = check_end_entity(ctx, dane, cert)) > 0) {
+ ctx->error_depth = 0;
+ ctx->current_cert = cert;
+ return cb(1, ctx);
+ }
+ if (matched < 0) {
+ X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
+ return -1;
+ }
+ }
+
+ if (dane->selectors[SSL_DANE_USAGE_TRUSTED_CA]) {
+ if ((matched = set_trust_anchor(ctx, dane, cert)) < 0) {
+ X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
+ return -1;
+ }
+ if (matched) {
+ /*
+ * Check that setting the untrusted chain updates the expected
+ * structure member at the expected offset.
+ */
+ X509_STORE_CTX_trusted_stack(ctx, dane->roots);
+ X509_STORE_CTX_set_chain(ctx, dane->chain);
+ OPENSSL_assert(ctx->untrusted == dane->chain);
+ }
+ }
+
+ /*
+ * Name checks and usage 0/1 constraint enforcement are delayed until
+ * X509_verify_cert() builds the full chain and calls our verify_chain()
+ * wrapper.
+ */
+ dane->verify = ctx->verify;
+ ctx->verify = verify_chain;
+
+ return X509_verify_cert(ctx);
+}
+
+static dane_list list_alloc(size_t vsize)
+{
+ void *value = (void *) OPENSSL_malloc(vsize);
+ dane_list l;
+
+ if (value == 0) {
+ DANEerr(DANE_F_LIST_ALLOC, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ if ((l = (dane_list) OPENSSL_malloc(sizeof(*l))) == 0) {
+ OPENSSL_free(value);
+ DANEerr(DANE_F_LIST_ALLOC, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ l->next = 0;
+ l->value = value;
+ return l;
+}
+
+static void list_free(void *list, void (*f)(void *))
+{
+ dane_list head = (dane_list) list;
+ dane_list next;
+
+ for (/* NOP */; head; head = next) {
+ next = head->next;
+ if (f && head->value)
+ f(head->value);
+ OPENSSL_free(head);
+ }
+}
+
+static void dane_mtype_free(void *p)
+{
+ list_free(((dane_mtype) p)->data, OPENSSL_freeFunc);
+ OPENSSL_free(p);
+}
+
+static void dane_selector_free(void *p)
+{
+ list_free(((dane_selector) p)->mtype, dane_mtype_free);
+ OPENSSL_free(p);
+}
+
+void DANESSL_cleanup(SSL *ssl)
+{
+ SSL_DANE *dane;
+ int u;
+
+ if (dane_idx < 0 || (dane = SSL_get_ex_data(ssl, dane_idx)) == 0)
+ return;
+ (void) SSL_set_ex_data(ssl, dane_idx, 0);
+
+ if (dane->hosts)
+ list_free(dane->hosts, OPENSSL_freeFunc);
+ if (dane->mhost)
+ OPENSSL_free(dane->mhost);
+ for (u = 0; u <= SSL_DANE_USAGE_LAST; ++u)
+ if (dane->selectors[u])
+ list_free(dane->selectors[u], dane_selector_free);
+ if (dane->pkeys)
+ list_free(dane->pkeys, pkey_free);
+ if (dane->certs)
+ list_free(dane->certs, cert_free);
+ if (dane->roots)
+ sk_X509_pop_free(dane->roots, X509_free);
+ if (dane->chain)
+ sk_X509_pop_free(dane->chain, X509_free);
+ OPENSSL_free(dane);
+}
+
+static DANE_HOST_LIST host_list_init(const char **src)
+{
+ DANE_HOST_LIST head = 0;
+
+ while (*src) {
+ DANE_HOST_LIST elem = (DANE_HOST_LIST) OPENSSL_malloc(sizeof(*elem));
+ if (elem == 0) {
+ list_free(head, OPENSSL_freeFunc);
+ return 0;
+ }
+ elem->value = OPENSSL_strdup(*src++);
+ LINSERT(head, elem);
+ }
+ return head;
+}
+
+int DANESSL_add_tlsa(
+ SSL *ssl,
+ uint8_t usage,
+ uint8_t selector,
+ const char *mdname,
+ unsigned const char *data,
+ size_t dlen
+)
+{
+ SSL_DANE *dane;
+ DANE_SELECTOR_LIST s = 0;
+ DANE_MTYPE_LIST m = 0;
+ DANE_DATA_LIST d = 0;
+ DANE_CERT_LIST xlist = 0;
+ DANE_PKEY_LIST klist = 0;
+ const EVP_MD *md = 0;
+
+ if (dane_idx < 0 || (dane = SSL_get_ex_data(ssl, dane_idx)) == 0) {
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_DANE_INIT);
+ return -1;
+ }
+
+ if (usage > SSL_DANE_USAGE_LAST) {
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_USAGE);
+ return 0;
+ }
+ if (selector > SSL_DANE_SELECTOR_LAST) {
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_SELECTOR);
+ return 0;
+ }
+ if (mdname && (md = EVP_get_digestbyname(mdname)) == 0) {
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_DIGEST);
+ return 0;
+ }
+ if (!data) {
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_NULL_DATA);
+ return 0;
+ }
+ if (mdname && dlen != EVP_MD_size(md)) {
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_DATA_LENGTH);
+ return 0;
+ }
+
+ if (mdname == 0) {
+ X509 *x = 0;
+ EVP_PKEY *k = 0;
+ const unsigned char *p = data;
+
+#define xklistinit(lvar, ltype, var, freeFunc) do { \
+ (lvar) = (ltype) OPENSSL_malloc(sizeof(*(lvar))); \
+ if ((lvar) == 0) { \
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, ERR_R_MALLOC_FAILURE); \
+ freeFunc((var)); \
+ return 0; \
+ } \
+ (lvar)->next = 0; \
+ lvar->value = var; \
+ } while (0)
+#define xkfreeret(ret) do { \
+ if (xlist) list_free(xlist, cert_free); \
+ if (klist) list_free(klist, pkey_free); \
+ return (ret); \
+ } while (0)
+
+ switch (selector) {
+ case SSL_DANE_SELECTOR_CERT:
+ if (!d2i_X509(&x, &p, dlen) || dlen != p - data) {
+ if (x)
+ X509_free(x);
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_CERT);
+ return 0;
+ }
+ k = X509_get_pubkey(x);
+ EVP_PKEY_free(k);
+ if (k == 0) {
+ X509_free(x);
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_CERT_PKEY);
+ return 0;
+ }
+ if (usage == SSL_DANE_USAGE_TRUSTED_CA)
+ xklistinit(xlist, DANE_CERT_LIST, x, X509_free);
+ break;
+
+ case SSL_DANE_SELECTOR_SPKI:
+ if (!d2i_PUBKEY(&k, &p, dlen) || dlen != p - data) {
+ if (k)
+ EVP_PKEY_free(k);
+ DANEerr(DANE_F_SSL_DANE_ADD_TLSA, DANE_R_BAD_PKEY);
+ return 0;
+ }
+ if (usage == SSL_DANE_USAGE_TRUSTED_CA)
+ xklistinit(klist, DANE_PKEY_LIST, k, EVP_PKEY_free);
+ break;
+ }
+ }
+
+ /* Find insertion point and don't add duplicate elements. */
+ for (s = dane->selectors[usage]; s; s = s->next)
+ if (s->value->selector == selector)
+ for (m = s->value->mtype; m; m = m->next)
+ if (m->value->md == md)
+ for (d = m->value->data; d; d = d->next)
+ if (d->value->datalen == dlen &&
+ memcmp(d->value->data, data, dlen) == 0)
+ xkfreeret(1);
+
+ if ((d = (DANE_DATA_LIST) list_alloc(sizeof(*d->value) + dlen)) == 0)
+ xkfreeret(0);
+ d->value->datalen = dlen;
+ memcpy(d->value->data, data, dlen);
+ if (!m) {
+ if ((m = (DANE_MTYPE_LIST) list_alloc(sizeof(*m->value))) == 0) {
+ list_free(d, OPENSSL_freeFunc);
+ xkfreeret(0);
+ }
+ m->value->data = 0;
+ if ((m->value->md = md) != 0)
+ m->value->mdlen = dlen;
+ if (!s) {
+ if ((s = (DANE_SELECTOR_LIST) list_alloc(sizeof(*s->value))) == 0) {
+ list_free(m, dane_mtype_free);
+ xkfreeret(0);
+ }
+ s->value->mtype = 0;
+ s->value->selector = selector;
+ LINSERT(dane->selectors[usage], s);
+ }
+ LINSERT(s->value->mtype, m);
+ }
+ LINSERT(m->value->data, d);
+
+ if (xlist)
+ LINSERT(dane->certs, xlist);
+ else if (klist)
+ LINSERT(dane->pkeys, klist);
+ ++dane->count;
+ return 1;
+}
+
+int DANESSL_init(SSL *ssl, const char *sni_domain, const char **hostnames)
+{
+ SSL_DANE *dane;
+ int i;
+#ifdef OPENSSL_INTERNAL
+ SSL_CTX *sctx = SSL_get_SSL_CTX(ssl);
+
+ if (sctx->app_verify_callback != verify_cert) {
+ DANEerr(DANE_F_SSL_DANE_INIT, DANE_R_SCTX_INIT);
+ return -1;
+ }
+#else
+ if (dane_idx < 0) {
+ DANEerr(DANE_F_SSL_DANE_INIT, DANE_R_LIBRARY_INIT);
+ return -1;
+ }
+#endif
+
+ if (sni_domain && !SSL_set_tlsext_host_name(ssl, sni_domain))
+ return 0;
+
+ if ((dane = (SSL_DANE *) OPENSSL_malloc(sizeof(SSL_DANE))) == 0) {
+ DANEerr(DANE_F_SSL_DANE_INIT, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+ if (!SSL_set_ex_data(ssl, dane_idx, dane)) {
+ DANEerr(DANE_F_SSL_DANE_INIT, ERR_R_MALLOC_FAILURE);
+ OPENSSL_free(dane);
+ return 0;
+ }
+
+ dane->pkeys = 0;
+ dane->certs = 0;
+ dane->chain = 0;
+ dane->roots = 0;
+ dane->depth = -1;
+ dane->mhost = 0; /* Future SSL control interface */
+ dane->multi = 0; /* Future SSL control interface */
+ dane->count = 0;
+
+ for (i = 0; i <= SSL_DANE_USAGE_LAST; ++i)
+ dane->selectors[i] = 0;
+
+ if (hostnames && (dane->hosts = host_list_init(hostnames)) == 0) {
+ DANEerr(DANE_F_SSL_DANE_INIT, ERR_R_MALLOC_FAILURE);
+ DANESSL_cleanup(ssl);
+ return 0;
+ }
+
+ return 1;
+}
+
+int DANESSL_CTX_init(SSL_CTX *ctx)
+{
+ if (dane_idx >= 0) {
+ SSL_CTX_set_cert_verify_callback(ctx, verify_cert, 0);
+ return 1;
+ }
+ DANEerr(DANE_F_SSL_CTX_DANE_INIT, DANE_R_LIBRARY_INIT);
+ return -1;
+}
+
+static int init_once(
+ volatile int *value,
+ int (*init)(void),
+ void (*postinit)(void)
+)
+{
+ int wlock = 0;
+
+ CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);
+ if (*value < 0) {
+ CRYPTO_r_unlock(CRYPTO_LOCK_SSL_CTX);
+ CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
+ wlock = 1;
+ if (*value < 0) {
+ *value = init();
+ if (postinit)
+ postinit();
+ }
+ }
+ if (wlock)
+ CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
+ else
+ CRYPTO_r_unlock(CRYPTO_LOCK_SSL_CTX);
+ return *value;
+}
+
+static void dane_init(void)
+{
+ /*
+ * Store library id in zeroth function slot, used to locate the library
+ * name. This must be done before we load the error strings.
+ */
+#ifndef OPENSSL_NO_ERR
+ dane_str_functs[0].error |= ERR_PACK(err_lib_dane, 0, 0);
+ ERR_load_strings(err_lib_dane, dane_str_functs);
+ ERR_load_strings(err_lib_dane, dane_str_reasons);
+#endif
+
+ /*
+ * Register SHA-2 digests, if implemented and not already registered.
+ */
+#if defined(LN_sha256) && defined(NID_sha256) && !defined(OPENSSL_NO_SHA256)
+ if (!EVP_get_digestbyname(LN_sha224))
+ EVP_add_digest(EVP_sha224());
+ if (!EVP_get_digestbyname(LN_sha256))
+ EVP_add_digest(EVP_sha256());
+#endif
+#if defined(LN_sha512) && defined(NID_sha512) && !defined(OPENSSL_NO_SHA512)
+ if (!EVP_get_digestbyname(LN_sha384))
+ EVP_add_digest(EVP_sha384());
+ if (!EVP_get_digestbyname(LN_sha512))
+ EVP_add_digest(EVP_sha512());
+#endif
+
+ /*
+ * Register an SSL index for the connection-specific SSL_DANE structure.
+ * Using a separate index makes it possible to add DANE support to
+ * existing OpenSSL releases that don't have a suitable pointer in the
+ * SSL structure.
+ */
+ dane_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
+}
+
+int DANESSL_library_init(void)
+{
+ if (err_lib_dane < 0)
+ init_once(&err_lib_dane, ERR_get_next_error_library, dane_init);
+
+#if defined(LN_sha256)
+ /* No DANE without SHA256 support */
+ if (dane_idx >= 0 && EVP_get_digestbyname(LN_sha256) != 0)
+ return 1;
+#endif
+ DANEerr(DANE_F_SSL_DANE_LIBRARY_INIT, DANE_R_DANE_SUPPORT);
+ return 0;
+}
+
+#endif /* OPENSSL_VERSION_NUMBER */
diff --git a/src/src/dane.c b/src/src/dane.c
new file mode 100644
index 0000000..54fd00c
--- /dev/null
+++ b/src/src/dane.c
@@ -0,0 +1,46 @@
+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2012 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is
+based on a patch that was originally contributed by Steve Haslam. It was
+adapted from stunnel, a GPL program by Michal Trojnara. The code for GNU TLS is
+based on a patch contributed by Nikos Mavroyanopoulos. Because these packages
+are so very different, the functions for each are kept in separate files. The
+relevant file is #included as required, after any any common functions.
+
+No cryptographic code is included in Exim. All this module does is to call
+functions from the OpenSSL or GNU TLS libraries. */
+
+
+#include "exim.h"
+
+/* This module is compiled only when it is specifically requested in the
+build-time configuration. However, some compilers don't like compiling empty
+modules, so keep them happy with a dummy when skipping the rest. Make it
+reference itself to stop picky compilers complaining that it is unused, and put
+in a dummy argument to stop even pickier compilers complaining about infinite
+loops. */
+
+#ifndef EXPERIMENTAL_DANE
+static void dummy(int x) { dummy(x-1); }
+#else
+
+/* Enabling DANE without enabling TLS cannot work. Abort the compilation. */
+#ifndef SUPPORT_TLS
+#error DANE support requires that TLS support must be enabled. Abort build.
+#endif
+
+#ifdef USE_GNUTLS
+#include "dane-gnu.c"
+#else
+#include "dane-openssl.c"
+#endif
+
+
+#endif /* EXPERIMENTAL_DANE */
+
+/* End of dane.c */
diff --git a/src/src/danessl.h b/src/src/danessl.h
new file mode 100644
index 0000000..5b1584d
--- /dev/null
+++ b/src/src/danessl.h
@@ -0,0 +1,31 @@
+#ifndef HEADER_SSL_DANE_H
+#define HEADER_SSL_DANE_H
+
+#include <stdint.h>
+#include <openssl/ssl.h>
+
+/*-
+ * Certificate usages:
+ * https://tools.ietf.org/html/rfc6698#section-2.1.1
+ */
+#define SSL_DANE_USAGE_LIMIT_ISSUER 0
+#define SSL_DANE_USAGE_LIMIT_LEAF 1
+#define SSL_DANE_USAGE_TRUSTED_CA 2
+#define SSL_DANE_USAGE_FIXED_LEAF 3
+#define SSL_DANE_USAGE_LAST SSL_DANE_USAGE_FIXED_LEAF
+
+/*-
+ * Selectors:
+ * https://tools.ietf.org/html/rfc6698#section-2.1.2
+ */
+#define SSL_DANE_SELECTOR_CERT 0
+#define SSL_DANE_SELECTOR_SPKI 1
+#define SSL_DANE_SELECTOR_LAST SSL_DANE_SELECTOR_SPKI
+
+extern int DANESSL_library_init(void);
+extern int DANESSL_CTX_init(SSL_CTX *);
+extern int DANESSL_init(SSL *, const char *, const char **);
+extern void DANESSL_cleanup(SSL *);
+extern int DANESSL_add_tlsa(SSL *, uint8_t, uint8_t, const char *,
+ unsigned const char *, size_t);
+#endif
diff --git a/src/src/globals.c b/src/src/globals.c
index d3f9987..7d4ab63 100644
--- a/src/src/globals.c
+++ b/src/src/globals.c
@@ -633,6 +633,9 @@ BOOL dmarc_enable_forensic = FALSE;
uschar *dns_again_means_nonexist = NULL;
int dns_csa_search_limit = 5;
BOOL dns_csa_use_reverse = TRUE;
+#ifdef EXPERIMENTAL_DANE
+int dns_dane_ok = -1;
+#endif
uschar *dns_ipv4_lookup = NULL;
int dns_retrans = 0;
int dns_retry = 0;
diff --git a/src/src/globals.h b/src/src/globals.h
index 2bedcf5..32ddd16 100644
--- a/src/src/globals.h
+++ b/src/src/globals.h
@@ -385,6 +385,9 @@ extern uschar *dns_again_means_nonexist; /* Domains that are badly set up */
extern int dns_csa_search_limit; /* How deep to search for CSA SRV records */
extern BOOL dns_csa_use_reverse; /* Check CSA in reverse DNS? (non-standard) */
extern uschar *dns_ipv4_lookup; /* For these domains, don't look for AAAA (or A6) */
+#ifdef EXPERIMENTAL_DANE
+extern int dns_dane_ok; /* Ok to use DANE when checking TLS authenticity */
+#endif
extern int dns_retrans; /* Retransmission time setting */
extern int dns_retry; /* Number of retries */
extern int dns_dnssec_ok; /* When constructing DNS query, set DO flag */
