Commit 338fb168 authored by Richard Levitte's avatar Richard Levitte
Browse files

Check that the subject name in a proxy cert complies to RFC 3820 



The subject name MUST be the same as the issuer name, with a single CN
entry added.

RT#1852

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
parent ad64a69e

crypto/x509/x509.h

+4 −2
Original line number Diff line number Diff line
@@ -1234,6 +1234,7 @@ int X509_TRUST_get_trust(X509_TRUST *xp); 
 * The following lines are auto generated by the script mkerr.pl. Any changes

 * made after this point may be overwritten when the script is next run.

 */



void ERR_load_X509_strings(void);



/* Error codes for the X509 functions. */
@@ -1241,6 +1242,7 @@ void ERR_load_X509_strings(void); 
/* Function codes. */

# define X509_F_ADD_CERT_DIR                              100

# define X509_F_BY_FILE_CTRL                              101

# define X509_F_CHECK_NAME_CONSTRAINTS                    106

# define X509_F_CHECK_POLICY                              145

# define X509_F_DIR_CTRL                                  102

# define X509_F_GET_CERT_BY_SUBJECT                       103

crypto/x509/x509_err.c

+2 −1
Original line number Diff line number Diff line 
/* crypto/x509/x509_err.c */

/* ====================================================================

 * Copyright (c) 1999-2012 The OpenSSL Project.  All rights reserved.

 * Copyright (c) 1999-2016 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions
@@ -72,6 +72,7 @@ 
static ERR_STRING_DATA X509_str_functs[] = {

    {ERR_FUNC(X509_F_ADD_CERT_DIR), "ADD_CERT_DIR"},

    {ERR_FUNC(X509_F_BY_FILE_CTRL), "BY_FILE_CTRL"},

    {ERR_FUNC(X509_F_CHECK_NAME_CONSTRAINTS), "CHECK_NAME_CONSTRAINTS"},

    {ERR_FUNC(X509_F_CHECK_POLICY), "CHECK_POLICY"},

    {ERR_FUNC(X509_F_DIR_CTRL), "DIR_CTRL"},

    {ERR_FUNC(X509_F_GET_CERT_BY_SUBJECT), "GET_CERT_BY_SUBJECT"},

crypto/x509/x509_txt.c

+2 −0
Original line number Diff line number Diff line
@@ -208,6 +208,8 @@ const char *X509_verify_cert_error_string(long n) 
        return ("Invalid certificate verification context");

    case X509_V_ERR_STORE_LOOKUP:

        return ("Issuer certificate lookup error");

    case X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION:

        return ("proxy subject name violation");



    default:

        BIO_snprintf(buf, sizeof buf, "error number %ld", n);

crypto/x509/x509_vfy.c

+75 −0
Original line number Diff line number Diff line
@@ -742,6 +742,81 @@ static int check_name_constraints(X509_STORE_CTX *ctx) 
        /* Ignore self issued certs unless last in chain */

        if (i && (x->ex_flags & EXFLAG_SI))

            continue;



        /*

         * Proxy certificates policy has an extra constraint, where the

         * certificate subject MUST be the issuer with a single CN entry

         * added.

         * (RFC 3820: 3.4, 4.1.3 (a)(4))

         */

        if (x->ex_flags & EXFLAG_PROXY) {

            X509_NAME *tmpsubject = X509_get_subject_name(x);

            X509_NAME *tmpissuer = X509_get_issuer_name(x);

            X509_NAME_ENTRY *tmpentry = NULL;

            int last_object_nid = 0;

            int err = X509_V_OK;

            int last_object_loc = X509_NAME_entry_count(tmpsubject) - 1;



            /* Check that there are at least two RDNs */

            if (last_object_loc < 1) {

                err = X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION;

                goto proxy_name_done;

            }



            /*

             * Check that there is exactly one more RDN in subject as

             * there is in issuer.

             */

            if (X509_NAME_entry_count(tmpsubject)

                != X509_NAME_entry_count(tmpissuer) + 1) {

                err = X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION;

                goto proxy_name_done;

            }



            /*

             * Check that the last subject component isn't part of a

             * multivalued RDN

             */

            if (X509_NAME_get_entry(tmpsubject, last_object_loc)->set

                == X509_NAME_get_entry(tmpsubject, last_object_loc - 1)->set) {

                err = X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION;

                goto proxy_name_done;

            }



            /*

             * Check that the last subject RDN is a commonName, and that

             * all the previous RDNs match the issuer exactly

             */

            tmpsubject = X509_NAME_dup(tmpsubject);

            if (tmpsubject == NULL) {

                X509err(X509_F_CHECK_NAME_CONSTRAINTS, ERR_R_MALLOC_FAILURE);

                ctx->error = X509_V_ERR_OUT_OF_MEM;

                return 0;

            }



            tmpentry =

                X509_NAME_delete_entry(tmpsubject, last_object_loc);

            last_object_nid =

                OBJ_obj2nid(X509_NAME_ENTRY_get_object(tmpentry));



            if (last_object_nid != NID_commonName

                || X509_NAME_cmp(tmpsubject, tmpissuer) != 0) {

                err = X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION;

            }



            X509_NAME_ENTRY_free(tmpentry);

            X509_NAME_free(tmpsubject);



         proxy_name_done:

            if (err != X509_V_OK) {

                ctx->error = err;

                ctx->error_depth = i;

                ctx->current_cert = x;

                if (!ctx->verify_cb(0, ctx))

                    return 0;

            }

        }



        /*

         * Check against constraints for all certificates higher in chain

         * including trust anchor. Trust anchor not strictly speaking needed

crypto/x509/x509_vfy.h

+2 −0
Original line number Diff line number Diff line
@@ -392,6 +392,8 @@ void X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth); 
/* Issuer lookup error */

# define         X509_V_ERR_STORE_LOOKUP                         66



# define         X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION         67



/* Certificate verify flags */



/* Send issuer+subject checks to verify_cb */