Initial support for name constraints certificate extension.
authorDr. Stephen Henson <steve@openssl.org>
Fri, 8 Aug 2008 15:35:29 +0000 (15:35 +0000)
committerDr. Stephen Henson <steve@openssl.org>
Fri, 8 Aug 2008 15:35:29 +0000 (15:35 +0000)
TODO: robustness checking on name forms.

CHANGES
crypto/asn1/x_x509.c
crypto/ossl_typ.h
crypto/x509/x509.h
crypto/x509/x509_txt.c
crypto/x509/x509_vfy.c
crypto/x509/x509_vfy.h
crypto/x509v3/v3_ncons.c
crypto/x509v3/v3_purp.c
crypto/x509v3/x509v3.h

diff --git a/CHANGES b/CHANGES
index 9b524dd..0d83a86 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,18 @@
 
  Changes between 0.9.8i and 0.9.9  [xx XXX xxxx]
 
+  *) Fixes to pathlength constraint, self issued certificate handling,
+     policy processing to align with RFC3280 and PKITS tests.
+
+     This work was sponsored by Google.
+     [Steve Henson]
+
+  *) Support for name constraints certificate extension. DN, email, DNS
+     and URI types are currently supported.
+
+     This work was sponsored by Google.
+     [Steve Henson]
+
   *) To cater for systems that provide a pointer-based thread ID rather
      than numeric, deprecate the current numeric thread ID mechanism and
      replace it with a structure and associated callback type. This
@@ -31,6 +43,8 @@
   *) Initial support for different CRL issuing certificates. This covers a
      simple case where the self issued certificates in the chain exist and
      the real CRL issuer is higher in the existing chain.
+
+     This work was sponsored by Google.
      [Steve Henson]
 
   *) Removed effectively defunct crypto/store from the build.
index a3cae2c..dafd3cc 100644 (file)
@@ -116,6 +116,8 @@ static int x509_cb(int operation, ASN1_VALUE **pval, const ASN1_ITEM *it,
                AUTHORITY_KEYID_free(ret->akid);
                CRL_DIST_POINTS_free(ret->crldp);
                policy_cache_free(ret->policy_cache);
+               GENERAL_NAMES_free(ret->altname);
+               NAME_CONSTRAINTS_free(ret->nc);
 #ifndef OPENSSL_NO_RFC3779
                sk_IPAddressFamily_pop_free(ret->rfc3779_addr, IPAddressFamily_free);
                ASIdentifiers_free(ret->rfc3779_asid);
index c9b494c..786f2bc 100644 (file)
@@ -177,6 +177,7 @@ typedef struct X509_POLICY_CACHE_st X509_POLICY_CACHE;
 typedef struct AUTHORITY_KEYID_st AUTHORITY_KEYID;
 typedef struct DIST_POINT_st DIST_POINT;
 typedef struct ISSUING_DIST_POINT_st ISSUING_DIST_POINT;
+typedef struct NAME_CONSTRAINTS_st NAME_CONSTRAINTS;
 
   /* If placed in pkcs12.h, we end up with a circular depency with pkcs7.h */
 #define DECLARE_PKCS12_STACK_OF(type) /* Nothing */
index 036ba7a..adbdc65 100644 (file)
@@ -294,6 +294,8 @@ struct x509_st
        AUTHORITY_KEYID *akid;
        X509_POLICY_CACHE *policy_cache;
        STACK_OF(DIST_POINT) *crldp;
+       STACK_OF(GENERAL_NAME) *altname;
+       NAME_CONSTRAINTS *nc;
 #ifndef OPENSSL_NO_RFC3779
        STACK_OF(IPAddressFamily) *rfc3779_addr;
        struct ASIdentifiers_st *rfc3779_asid;
index 3851869..2017f86 100644 (file)
@@ -168,6 +168,20 @@ const char *X509_verify_cert_error_string(long n)
        return("Unsupported extension feature");
        case X509_V_ERR_UNNESTED_RESOURCE:
                return("RFC 3779 resource not subset of parent's resources");
+
+       case X509_V_ERR_PERMITTED_VIOLATION:
+               return("permitted subtree violation");
+       case X509_V_ERR_EXCLUDED_VIOLATION:
+               return("excluded subtree violation");
+       case X509_V_ERR_SUBTREE_MINMAX:
+               return("name constraints minimum and maximum not supported");
+       case X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE:
+               return("unsupported name constraint type");
+       case X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX:
+               return("unsupported or invalid name constraint syntax");
+       case X509_V_ERR_UNSUPPORTED_NAME_SYNTAX:
+               return("unsupported or invalid name syntax");
+
        default:
                BIO_snprintf(buf,sizeof buf,"error number %ld",n);
                return(buf);
index 1b1630a..fe47dcb 100644 (file)
@@ -74,6 +74,7 @@ static int null_callback(int ok,X509_STORE_CTX *e);
 static int check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer);
 static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x);
 static int check_chain_extensions(X509_STORE_CTX *ctx);
+static int check_name_constraints(X509_STORE_CTX *ctx);
 static int check_trust(X509_STORE_CTX *ctx);
 static int check_revocation(X509_STORE_CTX *ctx);
 static int check_cert(X509_STORE_CTX *ctx);
@@ -291,6 +292,12 @@ int X509_verify_cert(X509_STORE_CTX *ctx)
 
        if (!ok) goto end;
 
+       /* Check name constraints */
+
+       ok = check_name_constraints(ctx);
+       
+       if (!ok) goto end;
+
        /* The chain extensions are OK: check trust */
 
        if (param->trust > 0) ok = check_trust(ctx);
@@ -538,6 +545,42 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
 #endif
 }
 
+static int check_name_constraints(X509_STORE_CTX *ctx)
+       {
+       X509 *x;
+       int i, j, rv;
+       /* Check name constraints for all certificates */
+       for (i = sk_X509_num(ctx->chain) - 1; i >= 0; i--)
+               {
+               x = sk_X509_value(ctx->chain, i);
+               /* Ignore self issued certs unless last in chain */
+               if (i && (x->ex_flags & EXFLAG_SI))
+                       continue;
+               /* Check against constraints for all certificates higher in
+                * chain including trust anchor. Trust anchor not strictly
+                * speaking needed but if it includes constraints it is to be
+                * assumed it expects them to be obeyed.
+                */
+               for (j = sk_X509_num(ctx->chain) - 1; j > i; j--)
+                       {
+                       NAME_CONSTRAINTS *nc = sk_X509_value(ctx->chain, j)->nc;
+                       if (nc)
+                               {
+                               rv = NAME_CONSTRAINTS_check(x, nc);
+                               if (rv != X509_V_OK)
+                                       {
+                                       ctx->error = rv;
+                                       ctx->error_depth = i;
+                                       ctx->current_cert = x;
+                                       if (!ctx->verify_cb(0,ctx))
+                                               return 0;
+                                       }
+                               }
+                       }
+               }
+       return 1;
+       }
+
 static int check_trust(X509_STORE_CTX *ctx)
 {
 #ifdef OPENSSL_NO_CHAIN_VERIFY
index 955af83..faf641f 100644 (file)
@@ -341,6 +341,13 @@ void X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth);
 
 #define                X509_V_ERR_UNNESTED_RESOURCE                    46
 
+#define                X509_V_ERR_PERMITTED_VIOLATION                  47
+#define                X509_V_ERR_EXCLUDED_VIOLATION                   48
+#define                X509_V_ERR_SUBTREE_MINMAX                       49
+#define                X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE          51
+#define                X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX        52
+#define                X509_V_ERR_UNSUPPORTED_NAME_SYNTAX              53
+
 /* The application is not happy */
 #define                X509_V_ERR_APPLICATION_VERIFICATION             50
 
index 42e7f5a..511fbd7 100644 (file)
@@ -72,6 +72,13 @@ static int do_i2r_name_constraints(X509V3_EXT_METHOD *method,
                                        BIO *bp, int ind, char *name);
 static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip);
 
+static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);
+static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen);
+static int nc_dn(X509_NAME *sub, X509_NAME *nm);
+static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns);
+static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml);
+static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base);
+
 const X509V3_EXT_METHOD v3_name_constraints = {
        NID_name_constraints, 0,
        ASN1_ITEM_ref(NAME_CONSTRAINTS),
@@ -218,3 +225,277 @@ static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip)
        return 1;
        }
 
+/* Check a certificate conforms to a specified set of constraints.
+ * Return values:
+ *  X509_V_OK: All constraints obeyed.
+ *  X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.
+ *  X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.
+ *  X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.
+ *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE:  Unsupported constraint type.
+ *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax.
+ *  X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name
+
+ */
+
+int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc)
+       {
+       int r, i;
+       X509_NAME *nm;
+
+       nm = X509_get_subject_name(x);
+
+       if (X509_NAME_entry_count(nm) > 0)
+               {
+               GENERAL_NAME gntmp;
+               gntmp.type = GEN_DIRNAME;
+               gntmp.d.directoryName = nm;
+
+               r = nc_match(&gntmp, nc);
+
+               if (r != X509_V_OK)
+                       return r;
+
+               gntmp.type = GEN_EMAIL;
+
+
+               /* Process any email address attributes in subject name */
+
+               for (i = -1;;)
+                       {
+                       X509_NAME_ENTRY *ne;
+                       i = X509_NAME_get_index_by_NID(nm,
+                                                      NID_pkcs9_emailAddress,
+                                                      i);
+                       if (i == -1)
+                               break;
+                       ne = X509_NAME_get_entry(nm, i);
+                       gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);
+                       if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING)
+                               return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
+
+                       r = nc_match(&gntmp, nc);
+
+                       if (r != X509_V_OK)
+                               return r;
+                       }
+               
+               }
+
+       for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++)
+               {
+               GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i);
+               r = nc_match(gen, nc);
+               if (r != X509_V_OK)
+                       return r;
+               }
+
+       return X509_V_OK;
+
+       }
+
+static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc)
+       {
+       GENERAL_SUBTREE *sub;
+       int i, r, match = 0;
+
+       /* Permitted subtrees: if any subtrees exist of matching the type
+        * at least one subtree must match.
+        */
+
+       for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++)
+               {
+               sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
+               if (gen->type != sub->base->type)
+                       continue;
+               if (sub->minimum || sub->maximum)
+                       return X509_V_ERR_SUBTREE_MINMAX;
+               /* If we already have a match don't bother trying any more */
+               if (match == 2)
+                       continue;
+               if (match == 0)
+                       match = 1;
+               r = nc_match_single(gen, sub->base);
+               if (r == X509_V_OK)
+                       match = 2;
+               else if (r != X509_V_ERR_PERMITTED_VIOLATION)
+                       return r;
+               }
+
+       if (match == 1)
+               return X509_V_ERR_PERMITTED_VIOLATION;
+
+       /* Excluded subtrees: must not match any of these */
+
+       for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++)
+               {
+               sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
+               if (gen->type != sub->base->type)
+                       continue;
+               if (sub->minimum || sub->maximum)
+                       return X509_V_ERR_SUBTREE_MINMAX;
+
+               r = nc_match_single(gen, sub->base);
+               if (r == X509_V_OK)
+                       return X509_V_ERR_EXCLUDED_VIOLATION;
+               else if (r != X509_V_ERR_PERMITTED_VIOLATION)
+                       return r;
+
+               }
+
+       return X509_V_OK;
+
+       }
+
+static int nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base)
+       {
+       switch(base->type)
+               {
+               case GEN_DIRNAME:
+               return nc_dn(gen->d.directoryName, base->d.directoryName);
+
+               case GEN_DNS:
+               return nc_dns(gen->d.dNSName, base->d.dNSName);
+
+               case GEN_EMAIL:
+               return nc_email(gen->d.rfc822Name, base->d.rfc822Name);
+
+               case GEN_URI:
+               return nc_uri(gen->d.uniformResourceIdentifier,
+                                       base->d.uniformResourceIdentifier);
+
+               default:
+               return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;
+               }
+
+       }
+
+/* directoryName name constraint matching.
+ * The canonical encoding of X509_NAME makes this comparison easy. It is
+ * matched if the subtree is a subset of the name.
+ */
+
+static int nc_dn(X509_NAME *nm, X509_NAME *base)
+       {
+       if (base->canon_enclen > nm->canon_enclen)
+               return X509_V_ERR_PERMITTED_VIOLATION;
+       if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen))
+               return X509_V_ERR_PERMITTED_VIOLATION;
+       return X509_V_OK;
+       }
+
+static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
+       {
+       char *baseptr = (char *)base->data;
+       char *dnsptr = (char *)dns->data;
+       /* Empty matches everything */
+       if (!*baseptr)
+               return X509_V_OK;
+       /* Otherwise can add zero or more components on the left so
+        * compare RHS and if dns is longer and expect '.' as preceding
+        * character.
+        */
+       if (dns->length > base->length)
+               {
+               dnsptr += dns->length - base->length;
+               if (dnsptr[-1] != '.')
+                       return X509_V_ERR_PERMITTED_VIOLATION;
+               }
+
+       if (strcasecmp(baseptr, dnsptr))
+                       return X509_V_ERR_PERMITTED_VIOLATION;
+
+       return X509_V_OK;
+
+       }
+
+static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
+       {
+       const char *baseptr = (char *)base->data;
+       const char *emlptr = (char *)eml->data;
+
+       const char *baseat = strchr(baseptr, '@');
+       const char *emlat = strchr(emlptr, '@');
+       if (!emlat)
+               return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
+       /* Special case: inital '.' is RHS match */
+       if (!baseat && (*baseptr == '.'))
+               {
+               if (eml->length > base->length)
+                       {
+                       emlptr += eml->length - base->length;
+                       if (!strcasecmp(baseptr, emlptr))
+                               return X509_V_OK;
+                       }
+               return X509_V_ERR_PERMITTED_VIOLATION;
+               }
+
+       /* If we have anything before '@' match local part */
+
+       if (baseat)
+               {
+               if (baseat != baseptr)
+                       {
+                       if ((baseat - baseptr) != (emlat - emlptr))
+                               return X509_V_ERR_PERMITTED_VIOLATION;
+                       /* Case sensitive match of local part */
+                       if (strncmp(baseptr, emlptr, emlat - emlptr))
+                               return X509_V_ERR_PERMITTED_VIOLATION;
+                       }
+               /* Position base after '@' */
+               baseptr = baseat + 1;
+               }
+       emlptr = emlat + 1;
+       /* Just have hostname left to match: case insensitive */
+       if (strcasecmp(baseptr, emlptr))
+               return X509_V_ERR_PERMITTED_VIOLATION;
+
+       return X509_V_OK;
+
+       }
+
+static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
+       {
+       const char *baseptr = (char *)base->data;
+       const char *hostptr = (char *)uri->data;
+       const char *p = strchr(hostptr, ':');
+       size_t hostlen;
+       /* Check for foo:// and skip past it */
+       if (!p || (p[1] != '/') || (p[2] != '/'))
+               return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
+       hostptr = p + 3;
+
+       /* Determine length of hostname part of URI */
+
+       /* Look for a port indicator as end of hostname first */
+
+       p = strchr(hostptr, ':');
+       /* Otherwise look for trailing slash */
+       if (!p)
+               p = strchr(hostptr, '/');
+
+       if (!p)
+               hostlen = strlen(hostptr);
+       else
+               hostlen = p - hostptr;
+
+       if (hostlen == 0)
+               return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
+
+       /* Special case: inital '.' is RHS match */
+       if (*baseptr == '.')
+               {
+               if (hostlen > base->length)
+                       {
+                       p = hostptr + hostlen - base->length;
+                       if (!strncasecmp(p, baseptr, base->length))
+                               return X509_V_OK;
+                       }
+               return X509_V_ERR_PERMITTED_VIOLATION;
+               }
+
+       if ((base->length != hostlen) || strncasecmp(hostptr, baseptr, hostlen))
+               return X509_V_ERR_PERMITTED_VIOLATION;
+
+       return X509_V_OK;
+
+       }
index caf80e6..7bb6658 100644 (file)
@@ -295,6 +295,7 @@ int X509_supported_extension(X509_EXTENSION *ex)
 #endif
                NID_policy_constraints, /* 401 */
                NID_proxyCertInfo,      /* 663 */
+               NID_name_constraints,   /* 666 */
                NID_inhibit_any_policy  /* 748 */
        };
 
@@ -448,6 +449,10 @@ static void x509v3_cache_extensions(X509 *x)
        }
        x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
        x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
+       x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
+       x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
+       if (!x->nc && (i != -1))
+               x->ex_flags |= EXFLAG_INVALID;
        setup_crldp(x);
                        
                        
index 5babc2b..c4a8cfc 100644 (file)
@@ -305,10 +305,10 @@ typedef struct GENERAL_SUBTREE_st {
 
 DECLARE_STACK_OF(GENERAL_SUBTREE)
 
-typedef struct NAME_CONSTRAINTS_st {
+struct NAME_CONSTRAINTS_st {
        STACK_OF(GENERAL_SUBTREE) *permittedSubtrees;
        STACK_OF(GENERAL_SUBTREE) *excludedSubtrees;
-} NAME_CONSTRAINTS;
+};
 
 typedef struct POLICY_CONSTRAINTS_st {
        ASN1_INTEGER *requireExplicitPolicy;
@@ -549,6 +549,8 @@ DECLARE_ASN1_FUNCTIONS(ISSUING_DIST_POINT)
 
 int DIST_POINT_set_dpname(DIST_POINT_NAME *dpn, X509_NAME *iname);
 
+int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc);
+
 DECLARE_ASN1_FUNCTIONS(ACCESS_DESCRIPTION)
 DECLARE_ASN1_FUNCTIONS(AUTHORITY_INFO_ACCESS)