In ssl_check_public_cert(), also take dNSNames in the subjectAltName

extension into account when checking the cert against the configured
ServerName. PR 32652, PR 47051.

Replace SSL_X509_getCN() by SSL_X509_getIDs(), which returns an array
of a cert's DNS-IDs and CN-IDs (terms as coined by RFC 6125).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1176752 13f79535-47bb-0310-9956-ffa450edef68

CHANGES

@@ -12,6 +12,10 @@ Changes with Apache 2.3.15
      PR 51714. [Stefan Fritsch, Jim Jagielski, Ruediger Pluem, Eric Covener,
      <lowprio20 gmail.com>]
 
+  *) mod_ssl: At startup, when checking a server certificate whether it
+     matches the configured ServerName, also take dNSName entries in the
+     subjectAltName extension into account. PR 32652, PR 47051. [Kaspar Brand]
+
   *) mod_substitute: Reduce memory usage and copying of data. PR 50559.
      [Stefan Fritsch]
 

modules/ssl/ssl_engine_init.c

@@ -985,7 +985,7 @@ static void ssl_check_public_cert(server_rec *s,
                                   int type)
 {
     int is_ca, pathlen;
-    char *cn;
+    apr_array_header_t *ids;
 
     if (!cert) {
         return;
@@ -1018,23 +1018,55 @@ static void ssl_check_public_cert(server_rec *s,
         }
     }
 
-    if (SSL_X509_getCN(ptemp, cert, &cn)) {
-        int fnm_flags = APR_FNM_PERIOD|APR_FNM_CASE_BLIND;
+    /*
+     * Check if the server name is covered by the certificate.
+     * Consider both dNSName entries in the subjectAltName extension
+     * and, as a fallback, commonName attributes in the subject DN.
+     * (DNS-IDs and CN-IDs as defined in RFC 6125).
+     */
+    if (SSL_X509_getIDs(ptemp, cert, &ids)) {
+        char *cp;
+        int i;
+        char **id = (char **)ids->elts;
+        BOOL is_wildcard, matched = FALSE;
 
-        if (apr_fnmatch_test(cn)) {
-            if (apr_fnmatch(cn, s->server_hostname,
-                            fnm_flags) == APR_FNM_NOMATCH) {
-                ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s,
-                             "%s server certificate wildcard CommonName "
-                             "(CN) `%s' does NOT match server name!?",
-                             ssl_asn1_keystr(type), cn);
+        for (i = 0; i < ids->nelts; i++) {
+            if (!id[i])
+                continue;
+
+            /*
+             * Determine if it is a wildcard ID - we're restrictive
+             * in the sense that we require the wildcard character to be
+             * THE left-most label (i.e., the ID must start with "*.")
+             */
+            is_wildcard = (*id[i] == '*' && *(id[i]+1) == '.') ? TRUE : FALSE;
+
+            /*
+             * If the ID includes a wildcard character, check if it matches
+             * for the left-most DNS label (i.e., the wildcard character
+             * is not allowed to match a dot). Otherwise, try a simple
+             * string compare, case insensitively.
+             */
+            if ((is_wildcard == TRUE &&
+                 (cp = strchr(s->server_hostname, '.')) &&
+                 !strcasecmp(id[i]+1, cp)) ||
+                !strcasecmp(id[i], s->server_hostname)) {
+                matched = TRUE;
+                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+                             "%sID '%s' in %s certificate configured "
+                             "for %s matches server name",
+                             is_wildcard ? "Wildcard " : "",
+                             id[i], ssl_asn1_keystr(type),
+                             (mySrvConfig(s))->vhost_id);
+                break;
             }
         }
-        else if (strNE(s->server_hostname, cn)) {
+
+        if (matched == FALSE) {
             ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s,
-                         "%s server certificate CommonName (CN) `%s' "
-                         "does NOT match server name!?",
-                         ssl_asn1_keystr(type), cn);
+                         "%s certificate configured for %s does NOT include "
+                         "an ID which matches the server name",
+                         ssl_asn1_keystr(type), (mySrvConfig(s))->vhost_id);
         }
     }
 }

modules/ssl/ssl_util_ssl.c

@@ -329,25 +329,54 @@ char *SSL_X509_NAME_to_string(apr_pool_t *p, X509_NAME *dn, unsigned int maxlen)
     return result;
 }
 
-/* retrieve subject CommonName of certificate */
-BOOL SSL_X509_getCN(apr_pool_t *p, X509 *xs, char **cppCN)
+/* return an array of (RFC 6125 coined) DNS-IDs and CN-IDs in a certificate */
+BOOL SSL_X509_getIDs(apr_pool_t *p, X509 *x509, apr_array_header_t **ids)
 {
-    X509_NAME *xsn;
-    X509_NAME_ENTRY *xsne;
-    int i, nid;
+    STACK_OF(GENERAL_NAME) *names;
+    BIO *bio;
+    X509_NAME *subj;
+    char **cpp;
+    int i, n;
 
-    xsn = X509_get_subject_name(xs);
-    for (i = 0; i < sk_X509_NAME_ENTRY_num((STACK_OF(X509_NAME_ENTRY) *)
-                                           xsn->entries); i++) {
-        xsne = sk_X509_NAME_ENTRY_value((STACK_OF(X509_NAME_ENTRY) *)
-                                        xsn->entries, i);
-        nid = OBJ_obj2nid((ASN1_OBJECT *)X509_NAME_ENTRY_get_object(xsne));
-        if (nid == NID_commonName) {
-            *cppCN = SSL_X509_NAME_ENTRY_to_string(p, xsne);
-            return TRUE;
-        }
+    if (!x509 || !(*ids = apr_array_make(p, 0, sizeof(char *)))) {
+        *ids = NULL;
+        return FALSE;
     }
-    return FALSE;
+
+    /* First, the DNS-IDs (dNSName entries in the subjectAltName extension) */
+    if ((names = X509_get_ext_d2i(x509, NID_subject_alt_name, NULL, NULL)) &&
+        (bio = BIO_new(BIO_s_mem()))) {
+        GENERAL_NAME *name;
+
+        for (i = 0; i < sk_GENERAL_NAME_num(names); i++) {
+            name = sk_GENERAL_NAME_value(names, i);
+            if (name->type == GEN_DNS) {
+                ASN1_STRING_print_ex(bio, name->d.ia5, ASN1_STRFLGS_ESC_CTRL|
+                                     ASN1_STRFLGS_UTF8_CONVERT);
+                n = BIO_pending(bio);
+                if (n > 0) {
+                    cpp = (char **)apr_array_push(*ids);
+                    *cpp = apr_palloc(p, n+1);
+                    n = BIO_read(bio, *cpp, n);
+                    (*cpp)[n] = NUL;
+                }
+            }
+        }
+        BIO_free(bio);
+    }
+
+    if (names)
+        sk_GENERAL_NAME_free(names);
+
+    /* Second, the CN-IDs (commonName attributes in the subject DN) */
+    subj = X509_get_subject_name(x509);
+    i = -1;
+    while ((i = X509_NAME_get_index_by_NID(subj, NID_commonName, i)) != -1) {
+        cpp = (char **)apr_array_push(*ids);
+        *cpp = SSL_X509_NAME_ENTRY_to_string(p, X509_NAME_get_entry(subj, i));
+    }
+
+    return apr_is_empty_array(*ids) ? FALSE : TRUE;
 }
 
 /*  _________________________________________________________________

modules/ssl/ssl_util_ssl.h

@@ -68,7 +68,7 @@ BOOL        SSL_X509_isSGC(X509 *);
 BOOL        SSL_X509_getBC(X509 *, int *, int *);
 char       *SSL_X509_NAME_ENTRY_to_string(apr_pool_t *p, X509_NAME_ENTRY *xsne);
 char       *SSL_X509_NAME_to_string(apr_pool_t *, X509_NAME *, unsigned int);
-BOOL        SSL_X509_getCN(apr_pool_t *, X509 *, char **);
+BOOL        SSL_X509_getIDs(apr_pool_t *, X509 *, apr_array_header_t **);
 BOOL        SSL_X509_INFO_load_file(apr_pool_t *, STACK_OF(X509_INFO) *, const char *);
 BOOL        SSL_X509_INFO_load_path(apr_pool_t *, STACK_OF(X509_INFO) *, const char *);
 int         SSL_CTX_use_certificate_chain(SSL_CTX *, char *, int, pem_password_cb *);