Make tls1_check_chain return a set of flags indicating checks passed
authorDr. Stephen Henson <steve@openssl.org>
Fri, 27 Jul 2012 13:39:23 +0000 (13:39 +0000)
committerDr. Stephen Henson <steve@openssl.org>
Fri, 27 Jul 2012 13:39:23 +0000 (13:39 +0000)
by a certificate chain. Add additional tests to handle client
certificates: checks for matching certificate type and issuer name
comparison.

Print out results of checks for each candidate chain tested in
s_server/s_client.

CHANGES
apps/s_cb.c
ssl/s3_clnt.c
ssl/ssl.h
ssl/ssl_cert.c
ssl/ssl_lib.c
ssl/ssl_locl.h
ssl/t1_lib.c

diff --git a/CHANGES b/CHANGES
index 46b23de..f320ef7 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,12 @@
 
  Changes between 1.0.1 and 1.1.0  [xx XXX xxxx]
 
+  *) Make tls1_check_chain return a set of flags indicating checks passed
+     by a certificate chain. Add additional tests to handle client
+     certificates: checks for matching certificate type and issuer name
+     comparison.
+     [Steve Henson]
+
   *) If an attempt is made to use a signature algorithm not in the peer
      preference list abort the handshake. If client has no suitable
      signature algorithms in response to a certificate request do not
index 2ac3f96..f7207c9 100644 (file)
@@ -1134,12 +1134,45 @@ struct  ssl_excert_st
        struct ssl_excert_st *next, *prev;
        };
 
+struct chain_flags
+       {
+       int flag;
+       const char *name;
+       };
+
+struct chain_flags chain_flags_list[] =
+       {
+               {CERT_PKEY_VALID, "Overall Validity"},
+               {CERT_PKEY_SIGN,  "Sign with EE key"},
+               {CERT_PKEY_EE_SIGNATURE, "EE signature"},
+               {CERT_PKEY_CA_SIGNATURE, "CA signature"},
+               {CERT_PKEY_EE_PARAM, "EE key parameters"},
+               {CERT_PKEY_CA_PARAM, "CA key parameters"},
+               {CERT_PKEY_EXPLICIT_SIGN,  "Explicity sign with EE key"},
+               {CERT_PKEY_ISSUER_NAME,  "Issuer Name"},
+               {CERT_PKEY_CERT_TYPE,  "Certificate Type"},
+               {0, NULL}
+       };
+
+
+static void print_chain_flags(BIO *out, int flags)
+       {
+       struct chain_flags *ctmp = chain_flags_list;
+       while(ctmp->name)
+               {
+               BIO_printf(out, "\t%s: %s\n", ctmp->name,
+                               flags & ctmp->flag ? "OK" : "NOT OK");
+               ctmp++;
+               }
+       }
+
 /* Very basic selection callback: just use any certificate chain
  * reported as valid. More sophisticated could prioritise according
  * to local policy.
  */
 static int set_cert_cb(SSL *ssl, void *arg)
        {
+       int i, rv;
        SSL_EXCERT *exc = arg;
        SSL_certs_clear(ssl);
 
@@ -1151,10 +1184,20 @@ static int set_cert_cb(SSL *ssl, void *arg)
         */
        while (exc->next)
                exc = exc->next;
-       
+
+       i = 0;  
+
        while(exc)
                {
-               if (SSL_check_chain(ssl, exc->cert, exc->key, exc->chain))
+               i++;
+               rv = SSL_check_chain(ssl, exc->cert, exc->key, exc->chain);
+               BIO_printf(bio_err, "Checking cert chain %d:\nSubject: ", i);
+               X509_NAME_print_ex(bio_err, X509_get_subject_name(exc->cert), 0,
+                                                       XN_FLAG_ONELINE);
+               BIO_puts(bio_err, "\n");
+               
+               print_chain_flags(bio_err, rv);
+               if (rv & CERT_PKEY_VALID)
                        {
                        SSL_use_certificate(ssl, exc->cert);
                        SSL_use_PrivateKey(ssl, exc->key);
index e9c1518..5adbb50 100644 (file)
@@ -1963,6 +1963,12 @@ int ssl3_get_certificate_request(SSL *s)
                        SSLerr(SSL_F_SSL3_GET_CERTIFICATE_REQUEST,SSL_R_DATA_LENGTH_TOO_LONG);
                        goto err;
                        }
+               /* Clear certificate digests and validity flags */
+               for (i = 0; i < SSL_PKEY_NUM; i++)
+                       {
+                       s->cert->pkeys[i].digest = NULL;
+                       s->cert->pkeys[i].valid_flags = 0;
+                       }
                if ((llen & 1) || !tls1_process_sigalgs(s, p, llen))
                        {
                        ssl3_send_alert(s,SSL3_AL_FATAL,SSL_AD_DECODE_ERROR);
index b8b1ba1..78ead35 100644 (file)
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -662,6 +662,26 @@ struct ssl_session_st
 /* Con't include root CA in chain */
 #define SSL_BUILD_CHAIN_FLAG_NO_ROOT   0x2
 
+/* Flags returned by SSL_check_chain */
+/* Certificate can be used with this session */
+#define CERT_PKEY_VALID                0x1
+/* Certificate can also be used for signing */
+#define CERT_PKEY_SIGN         0x2
+/* EE certificate signing algorithm OK */
+#define CERT_PKEY_EE_SIGNATURE 0x10
+/* CA signature algorithms OK */
+#define CERT_PKEY_CA_SIGNATURE 0x20
+/* EE certificate parameters OK */
+#define CERT_PKEY_EE_PARAM     0x40
+/* CA certificate parameters OK */
+#define CERT_PKEY_CA_PARAM     0x80
+/* Signing explicitly allowed as opposed to SHA1 fallback */
+#define CERT_PKEY_EXPLICIT_SIGN        0x100
+/* Client CA issuer names match (always set for server cert) */
+#define CERT_PKEY_ISSUER_NAME  0x200
+/* Cert type matches client types (always set for server cert) */
+#define CERT_PKEY_CERT_TYPE    0x400
+
 /* Note: SSL[_CTX]_set_{options,mode} use |= op on the previous value,
  * they cannot be used to clear bits. */
 
index 9547814..eb41cfd 100644 (file)
@@ -467,7 +467,8 @@ void ssl_cert_clear_certs(CERT *c)
                 if (cpk->authz != NULL)
                        OPENSSL_free(cpk->authz);
 #endif
-               cpk->valid_flags = 0;
+               /* Clear all flags apart from explicit sign */
+               cpk->valid_flags &= CERT_PKEY_EXPLICIT_SIGN;
                }
        }
 
index a0af428..bec87d8 100644 (file)
@@ -2086,21 +2086,21 @@ void ssl_set_cert_masks(CERT *c, const SSL_CIPHER *cipher)
        have_ecdh_tmp=(c->ecdh_tmp || c->ecdh_tmp_cb || c->ecdh_tmp_auto);
 #endif
        cpk= &(c->pkeys[SSL_PKEY_RSA_ENC]);
-       rsa_enc= cpk->valid_flags;
+       rsa_enc= cpk->valid_flags & CERT_PKEY_VALID;
        rsa_enc_export=(rsa_enc && EVP_PKEY_size(cpk->privatekey)*8 <= kl);
        cpk= &(c->pkeys[SSL_PKEY_RSA_SIGN]);
-       rsa_sign= (cpk->valid_flags & CERT_PKEY_SIGN);
+       rsa_sign= cpk->valid_flags & CERT_PKEY_SIGN;
        cpk= &(c->pkeys[SSL_PKEY_DSA_SIGN]);
-       dsa_sign= (cpk->valid_flags & CERT_PKEY_SIGN);
+       dsa_sign= cpk->valid_flags & CERT_PKEY_SIGN;
        cpk= &(c->pkeys[SSL_PKEY_DH_RSA]);
-       dh_rsa=  cpk->valid_flags;
+       dh_rsa=  cpk->valid_flags & CERT_PKEY_VALID;
        dh_rsa_export=(dh_rsa && EVP_PKEY_size(cpk->privatekey)*8 <= kl);
        cpk= &(c->pkeys[SSL_PKEY_DH_DSA]);
 /* FIX THIS EAY EAY EAY */
-       dh_dsa=  cpk->valid_flags;
+       dh_dsa=  cpk->valid_flags & CERT_PKEY_VALID;
        dh_dsa_export=(dh_dsa && EVP_PKEY_size(cpk->privatekey)*8 <= kl);
        cpk= &(c->pkeys[SSL_PKEY_ECC]);
-       have_ecc_cert= cpk->valid_flags;
+       have_ecc_cert= cpk->valid_flags & CERT_PKEY_VALID;
        mask_k=0;
        mask_a=0;
        emask_k=0;
index d8d1b79..1523303 100644 (file)
 #define NAMED_CURVE_TYPE           3
 #endif  /* OPENSSL_NO_EC */
 
-/* Values for valid_flags in CERT_PKEY structure */
-/* Certificate inconsistent with session, key missing etc */
-#define CERT_PKEY_INVALID      0x0
-/* Certificate can be used with this sesstion */
-#define CERT_PKEY_VALID                0x1
-/* Certificate can also be used for signing */
-#define CERT_PKEY_SIGN         0x2
-
 typedef struct cert_pkey_st
        {
        X509 *x509;
index 8b3c213..68bd709 100644 (file)
@@ -1451,6 +1451,7 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char
        unsigned short len;
        unsigned char *data = *p;
        int renegotiate_seen = 0;
+       size_t i;
 
        s->servername_done = 0;
        s->tlsext_status_type = -1;
@@ -1474,6 +1475,12 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char
                OPENSSL_free(s->cert->shared_sigalgs);
                s->cert->shared_sigalgs = NULL;
                }
+       /* Clear certificate digests and validity flags */
+       for (i = 0; i < SSL_PKEY_NUM; i++)
+               {
+               s->cert->pkeys[i].digest = NULL;
+               s->cert->pkeys[i].valid_flags = 0;
+               }
 
        if (data >= (d+n-2))
                goto ri_check;
@@ -1961,7 +1968,6 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char
                         * in the case of a session resumption. */
                        if (!s->hit)
                                {
-                               size_t i;
                                if (s->s3->tlsext_authz_client_types != NULL)
                                        OPENSSL_free(s->s3->tlsext_authz_client_types);
                                s->s3->tlsext_authz_client_types =
@@ -3180,11 +3186,6 @@ int tls1_process_sigalgs(SSL *s, const unsigned char *data, int dsize)
        if (!c)
                return 0;
 
-       c->pkeys[SSL_PKEY_DSA_SIGN].digest = NULL;
-       c->pkeys[SSL_PKEY_RSA_SIGN].digest = NULL;
-       c->pkeys[SSL_PKEY_RSA_ENC].digest = NULL;
-       c->pkeys[SSL_PKEY_ECC].digest = NULL;
-
        c->peer_sigalgs = OPENSSL_malloc(dsize);
        if (!c->peer_sigalgs)
                return 0;
@@ -3201,8 +3202,12 @@ int tls1_process_sigalgs(SSL *s, const unsigned char *data, int dsize)
                        {
                        md = tls12_get_hash(sigptr->rhash);
                        c->pkeys[idx].digest = md;
+                       c->pkeys[idx].valid_flags = CERT_PKEY_EXPLICIT_SIGN;
                        if (idx == SSL_PKEY_RSA_SIGN)
+                               {
+                               c->pkeys[SSL_PKEY_RSA_ENC].valid_flags = CERT_PKEY_EXPLICIT_SIGN;
                                c->pkeys[SSL_PKEY_RSA_ENC].digest = md;
+                               }
                        }
 
                }
@@ -3546,40 +3551,76 @@ static int tls1_check_sig_alg(CERT *c, X509 *x, int default_nid)
                        return 1;
        return 0;
        }
+/* Check to see if a certificate issuer name matches list of CA names */
+static int ssl_check_ca_name(STACK_OF(X509_NAME) *names, X509 *x)
+       {
+       X509_NAME *nm;
+       int i;
+       nm = X509_get_issuer_name(x);
+       for (i = 0; i < sk_X509_NAME_num(names); i++)
+               {
+               if(!X509_NAME_cmp(nm, sk_X509_NAME_value(names, i)))
+                       return 1;
+               }
+       return 0;
+       }
 
 /* Check certificate chain is consistent with TLS extensions and is
- * usable by server.
+ * usable by server. This servers two purposes: it allows users to 
+ * check chains before passing them to the server and it allows the
+ * server to check chains before attempting to use them.
  */
+
+/* Flags which need to be set for a certificate when stict mode not set */
+
+#define CERT_PKEY_VALID_FLAGS \
+       (CERT_PKEY_EE_SIGNATURE|CERT_PKEY_EE_PARAM)
+/* Strict mode flags */
+#define CERT_PKEY_STRICT_FLAGS \
+        (CERT_PKEY_VALID_FLAGS|CERT_PKEY_CA_SIGNATURE|CERT_PKEY_CA_PARAM \
+        | CERT_PKEY_ISSUER_NAME|CERT_PKEY_CERT_TYPE)
+
 int tls1_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain,
                                                                        int idx)
        {
        int i;
-       int rv = CERT_PKEY_INVALID;
+       int rv = 0;
+       int check_flags = 0, strict_mode;
        CERT_PKEY *cpk = NULL;
        CERT *c = s->cert;
+       /* idx != -1 means checking server chains */
        if (idx != -1)
                {
                cpk = c->pkeys + idx;
                x = cpk->x509;
                pk = cpk->privatekey;
                chain = cpk->chain;
+               strict_mode = c->cert_flags & SSL_CERT_FLAG_TLS_STRICT;
                /* If no cert or key, forget it */
                if (!x || !pk)
                        goto end;
                }
        else
                {
+               if (!x || !pk)
+                       goto end;
                idx = ssl_cert_type(x, pk);
                if (idx == -1)
                        goto end;
+               cpk = c->pkeys + idx;
+               if (c->cert_flags & SSL_CERT_FLAG_TLS_STRICT)
+                       check_flags = CERT_PKEY_STRICT_FLAGS;
+               else
+                       check_flags = CERT_PKEY_VALID_FLAGS;
+               strict_mode = 1;
                }
 
+
        /* Check all signature algorithms are consistent with
         * signature algorithms extension if TLS 1.2 or later
         * and strict mode.
         */
-       if (TLS1_get_version(s) >= TLS1_2_VERSION
-               && c->cert_flags & SSL_CERT_FLAG_TLS_STRICT)
+       if (TLS1_get_version(s) >= TLS1_2_VERSION && strict_mode)
                {
                int default_nid;
                unsigned char rsign = 0;
@@ -3627,39 +3668,171 @@ int tls1_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain,
                                        break;
                                }
                        if (j == c->conf_sigalgslen)
-                               goto end;
+                               {
+                               if (check_flags)
+                                       goto skip_sigs;
+                               else
+                                       goto end;
+                               }
                        }
                /* Check signature algorithm of each cert in chain */
                if (!tls1_check_sig_alg(c, x, default_nid))
-                       goto end;
+                       {
+                       if (!check_flags) goto end;
+                       }
+               else
+                       rv |= CERT_PKEY_EE_SIGNATURE;
+               rv |= CERT_PKEY_CA_SIGNATURE;
                for (i = 0; i < sk_X509_num(chain); i++)
                        {
                        if (!tls1_check_sig_alg(c, sk_X509_value(chain, i),
                                                        default_nid))
-                               goto end;
+                               {
+                               if (check_flags)
+                                       {
+                                       rv &= ~CERT_PKEY_CA_SIGNATURE;
+                                       break;
+                                       }
+                               else
+                                       goto end;
+                               }
                        }
                }
-
-       /* Check cert parameters are consistent */
-       if (!tls1_check_cert_param(s, x))
+       /* Else not TLS 1.2, so mark EE and CA signing algorithms OK */
+       else if(check_flags)
+               rv |= CERT_PKEY_EE_SIGNATURE|CERT_PKEY_CA_SIGNATURE;
+       skip_sigs:
+       /* Check cert parameters are consistent: server certs only */
+       if (!s->server || tls1_check_cert_param(s, x))
+               rv |= CERT_PKEY_EE_PARAM;
+       else if (!check_flags)
                goto end;
+       if (!s->server)
+               rv |= CERT_PKEY_CA_PARAM;
        /* In strict mode check rest of chain too */
-       if (c->cert_flags & SSL_CERT_FLAG_TLS_STRICT)
+       else if (strict_mode)
                {
+               rv |= CERT_PKEY_CA_PARAM;
                for (i = 0; i < sk_X509_num(chain); i++)
                        {
                        if (!tls1_check_cert_param(s, sk_X509_value(chain, i)))
+                               {
+                               if (check_flags)
+                                       {
+                                       rv &= ~CERT_PKEY_CA_PARAM;
+                                       break;
+                                       }
+                               else
+                                       goto end;
+                               }
+                       }
+               }
+       if (!s->server && strict_mode)
+               {
+               STACK_OF(X509_NAME) *ca_dn;
+               int check_type = 0;
+               switch (pk->type)
+                       {
+               case EVP_PKEY_RSA:
+                       check_type = TLS_CT_RSA_SIGN;
+                       break;
+               case EVP_PKEY_DSA:
+                       check_type = TLS_CT_DSS_SIGN;
+                       break;
+               case EVP_PKEY_EC:
+                       check_type = TLS_CT_ECDSA_SIGN;
+                       break;
+               case EVP_PKEY_DH:
+               case EVP_PKEY_DHX:
+                               {
+                               int cert_type = X509_certificate_type(x, pk);
+                               if (cert_type & EVP_PKS_RSA)
+                                       check_type = TLS_CT_RSA_FIXED_DH;
+                               if (cert_type & EVP_PKS_DSA)
+                                       check_type = TLS_CT_DSS_FIXED_DH;
+                               }
+                       }
+               if (check_type)
+                       {
+                       const unsigned char *ctypes;
+                       int ctypelen;
+                       if (c->ctypes)
+                               {
+                               ctypes = c->ctypes;
+                               ctypelen = (int)c->ctype_num;
+                               }
+                       else
+                               {
+                               ctypes = (unsigned char *)s->s3->tmp.ctype;
+                               ctypelen = s->s3->tmp.ctype_num;
+                               }
+                       for (i = 0; i < ctypelen; i++)
+                               {
+                               if (ctypes[i] == check_type)
+                                       {
+                                       rv |= CERT_PKEY_CERT_TYPE;
+                                       break;
+                                       }
+                               }
+                       if (!(rv & CERT_PKEY_CERT_TYPE) && !check_flags)
                                goto end;
                        }
+               else
+                       rv |= CERT_PKEY_CERT_TYPE;
+
+
+               ca_dn = s->s3->tmp.ca_names;
+
+               if (!sk_X509_NAME_num(ca_dn))
+                       rv |= CERT_PKEY_ISSUER_NAME;
+
+               if (!(rv & CERT_PKEY_ISSUER_NAME))
+                       {
+                       if (ssl_check_ca_name(ca_dn, x))
+                               rv |= CERT_PKEY_ISSUER_NAME;
+                       }
+               if (!(rv & CERT_PKEY_ISSUER_NAME))
+                       {
+                       for (i = 0; i < sk_X509_num(chain); i++)
+                               {
+                               X509 *xtmp = sk_X509_value(chain, i);
+                               if (ssl_check_ca_name(ca_dn, xtmp))
+                                       {
+                                       rv |= CERT_PKEY_ISSUER_NAME;
+                                       break;
+                                       }
+                               }
+                       }
+               if (!check_flags && !(rv & CERT_PKEY_ISSUER_NAME))
+                       goto end;
                }
-       rv = CERT_PKEY_VALID;
+       else
+               rv |= CERT_PKEY_ISSUER_NAME|CERT_PKEY_CERT_TYPE;
+
+       if (!check_flags || (rv & check_flags) == check_flags)
+               rv |= CERT_PKEY_VALID;
 
        end:
-       if (cpk)
+
+       if (TLS1_get_version(s) >= TLS1_2_VERSION)
                {
-               if (rv && cpk->digest)
+               if (cpk->valid_flags & CERT_PKEY_EXPLICIT_SIGN)
+                       rv |= CERT_PKEY_EXPLICIT_SIGN|CERT_PKEY_SIGN;
+               else if (cpk->digest)
                        rv |= CERT_PKEY_SIGN;
-               cpk->valid_flags = rv;
+               }
+       else
+               rv |= CERT_PKEY_SIGN|CERT_PKEY_EXPLICIT_SIGN;
+
+       /* When checking a CERT_PKEY structure all flags are irrelevant
+        * if the chain is invalid.
+        */
+       if (!check_flags)
+               {
+               if (rv & CERT_PKEY_VALID)
+                       cpk->valid_flags = rv;
+               else
+                       cpk->valid_flags = 0;
                }
        return rv;
        }