crypto: allow client/server cert chains

The existing implementation assumes that client/server certificates are
single individual certificates.  If using publicly-issued certificates,
or internal CAs that use an intermediate issuer, this is unlikely to be
the case, and they will instead be certificate chains.  While this can
be worked around by moving the intermediate certificates to the CA
certificate, which DOES currently support multiple certificates, this
instead allows the issued certificate chains to be used as-is, without
requiring the overhead of shuffling certificates around.

Corresponding libvirt change is available here:
https://gitlab.com/libvirt/libvirt/-/merge_requests/222

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: matoro <matoro_mailinglist_qemu@matoro.tk>
[DB: adapted for code conflicts with multi-CA patch]
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

diff --git a/crypto/tlscredsx509.c b/crypto/tlscredsx509.c
index 2eccd71b3c049e42732912df668497dd06053990..86fdfce886a9b2b36f266d4d52e650dc0373d8d0 100644 (file)
--- a/crypto/tlscredsx509.c
+++ b/crypto/tlscredsx509.c
@@ -317,7 +317,8 @@ qcrypto_tls_creds_check_cert(QCryptoTLSCredsX509 *creds,
 
 static int
 qcrypto_tls_creds_check_authority_chain(QCryptoTLSCredsX509 *creds,
-                                        gnutls_x509_crt_t cert,
+                                        gnutls_x509_crt_t *certs,
+                                        unsigned int ncerts,
                                         gnutls_x509_crt_t *cacerts,
                                         unsigned int ncacerts,
                                         const char *cacertFile,
@@ -325,9 +326,32 @@ qcrypto_tls_creds_check_authority_chain(QCryptoTLSCredsX509 *creds,
                                         bool isCA,
                                         Error **errp)
 {
-    gnutls_x509_crt_t cert_to_check = cert;
+    gnutls_x509_crt_t cert_to_check = certs[ncerts - 1];
     int retval = 0;
-    gnutls_datum_t dn = {};
+    gnutls_datum_t dn = {}, dnissuer = {};
+
+    for (int i = 0; i < (ncerts - 1); i++) {
+        if (!gnutls_x509_crt_check_issuer(certs[i], certs[i + 1])) {
+            retval = gnutls_x509_crt_get_dn2(certs[i], &dn);
+            if (retval < 0) {
+                error_setg(errp, "Unable to fetch cert DN: %s",
+                           gnutls_strerror(retval));
+                return -1;
+            }
+            retval = gnutls_x509_crt_get_dn2(certs[i + 1], &dnissuer);
+            if (retval < 0) {
+                g_free(dn.data);
+                error_setg(errp, "Unable to fetch cert DN: %s",
+                           gnutls_strerror(retval));
+                return -1;
+            }
+            error_setg(errp, "Cert '%s' does not match issuer of cert '%s'",
+                       dnissuer.data, dn.data);
+            g_free(dn.data);
+            g_free(dnissuer.data);
+            return -1;
+        }
+    }
 
     for (;;) {
         gnutls_x509_crt_t cert_issuer = NULL;
@@ -373,7 +397,8 @@ qcrypto_tls_creds_check_authority_chain(QCryptoTLSCredsX509 *creds,
 }
 
 static int
-qcrypto_tls_creds_check_cert_pair(gnutls_x509_crt_t cert,
+qcrypto_tls_creds_check_cert_pair(gnutls_x509_crt_t *certs,
+                                  size_t ncerts,
                                   const char *certFile,
                                   gnutls_x509_crt_t *cacerts,
                                   size_t ncacerts,
@@ -383,7 +408,7 @@ qcrypto_tls_creds_check_cert_pair(gnutls_x509_crt_t cert,
 {
     unsigned int status;
 
-    if (gnutls_x509_crt_list_verify(&cert, 1,
+    if (gnutls_x509_crt_list_verify(certs, ncerts,
                                     cacerts, ncacerts,
                                     NULL, 0,
                                     0, &status) < 0) {
@@ -425,66 +450,14 @@ qcrypto_tls_creds_check_cert_pair(gnutls_x509_crt_t cert,
 }
 
 
-static gnutls_x509_crt_t
-qcrypto_tls_creds_load_cert(QCryptoTLSCredsX509 *creds,
-                            const char *certFile,
-                            bool isServer,
-                            Error **errp)
-{
-    gnutls_datum_t data;
-    gnutls_x509_crt_t cert = NULL;
-    g_autofree char *buf = NULL;
-    gsize buflen;
-    GError *gerr = NULL;
-    int ret = -1;
-    int err;
-
-    trace_qcrypto_tls_creds_x509_load_cert(creds, isServer, certFile);
-
-    err = gnutls_x509_crt_init(&cert);
-    if (err < 0) {
-        error_setg(errp, "Unable to initialize certificate: %s",
-                   gnutls_strerror(err));
-        goto cleanup;
-    }
-
-    if (!g_file_get_contents(certFile, &buf, &buflen, &gerr)) {
-        error_setg(errp, "Cannot load CA cert list %s: %s",
-                   certFile, gerr->message);
-        g_error_free(gerr);
-        goto cleanup;
-    }
-
-    data.data = (unsigned char *)buf;
-    data.size = strlen(buf);
-
-    err = gnutls_x509_crt_import(cert, &data, GNUTLS_X509_FMT_PEM);
-    if (err < 0) {
-        error_setg(errp, isServer ?
-                   "Unable to import server certificate %s: %s" :
-                   "Unable to import client certificate %s: %s",
-                   certFile,
-                   gnutls_strerror(err));
-        goto cleanup;
-    }
-
-    ret = 0;
-
- cleanup:
-    if (ret != 0) {
-        gnutls_x509_crt_deinit(cert);
-        cert = NULL;
-    }
-    return cert;
-}
-
-
 static int
-qcrypto_tls_creds_load_ca_cert_list(QCryptoTLSCredsX509 *creds,
-                                    const char *certFile,
-                                    gnutls_x509_crt_t **certs,
-                                    unsigned int *ncerts,
-                                    Error **errp)
+qcrypto_tls_creds_load_cert_list(QCryptoTLSCredsX509 *creds,
+                                 const char *certFile,
+                                 gnutls_x509_crt_t **certs,
+                                 unsigned int *ncerts,
+                                 bool isServer,
+                                 bool isCA,
+                                 Error **errp)
 {
     gnutls_datum_t data;
     g_autofree char *buf = NULL;
@@ -507,7 +480,9 @@ qcrypto_tls_creds_load_ca_cert_list(QCryptoTLSCredsX509 *creds,
     if (gnutls_x509_crt_list_import2(certs, ncerts, &data,
                                      GNUTLS_X509_FMT_PEM, 0) < 0) {
         error_setg(errp,
-                   "Unable to import CA certificate list %s",
+                   isCA ? "Unable to import CA certificate list %s" :
+                   (isServer ? "Unable to import server certificate %s" :
+                    "Unable to import client certificate %s"),
                    certFile);
         return -1;
     }
@@ -523,7 +498,8 @@ qcrypto_tls_creds_x509_sanity_check(QCryptoTLSCredsX509 *creds,
                                     const char *certFile,
                                     Error **errp)
 {
-    gnutls_x509_crt_t cert = NULL;
+    gnutls_x509_crt_t *certs = NULL;
+    unsigned int ncerts = 0;
     gnutls_x509_crt_t *cacerts = NULL;
     unsigned int ncacerts = 0;
     size_t i;
@@ -531,41 +507,48 @@ qcrypto_tls_creds_x509_sanity_check(QCryptoTLSCredsX509 *creds,
 
     if (certFile &&
         access(certFile, R_OK) == 0) {
-        cert = qcrypto_tls_creds_load_cert(creds,
-                                           certFile, isServer,
-                                           errp);
-        if (!cert) {
+        if (qcrypto_tls_creds_load_cert_list(creds,
+                                             certFile,
+                                             &certs,
+                                             &ncerts,
+                                             isServer,
+                                             false,
+                                             errp) < 0) {
             goto cleanup;
         }
     }
     if (access(cacertFile, R_OK) == 0) {
-        if (qcrypto_tls_creds_load_ca_cert_list(creds,
-                                                cacertFile,
-                                                &cacerts,
-                                                &ncacerts,
-                                                errp) < 0) {
+        if (qcrypto_tls_creds_load_cert_list(creds,
+                                             cacertFile,
+                                             &cacerts,
+                                             &ncacerts,
+                                             isServer,
+                                             true,
+                                             errp) < 0) {
             goto cleanup;
         }
     }
 
-    if (cert &&
-        qcrypto_tls_creds_check_cert(creds,
-                                     cert, certFile, isServer,
-                                     false, errp) < 0) {
-        goto cleanup;
+    for (i = 0; i < ncerts; i++) {
+        if (qcrypto_tls_creds_check_cert(creds,
+                                         certs[i], certFile,
+                                         isServer, i != 0, errp) < 0) {
+            goto cleanup;
+        }
     }
 
-    if (cert &&
-        qcrypto_tls_creds_check_authority_chain(creds, cert,
+    if (ncerts &&
+        qcrypto_tls_creds_check_authority_chain(creds,
+                                                certs, ncerts,
                                                 cacerts, ncacerts,
                                                 cacertFile, isServer,
                                                 true, errp) < 0) {
         goto cleanup;
     }
 
-    if (cert && ncacerts &&
-        qcrypto_tls_creds_check_cert_pair(cert, certFile, cacerts,
-                                          ncacerts, cacertFile,
+    if (ncerts && ncacerts &&
+        qcrypto_tls_creds_check_cert_pair(certs, ncerts, certFile,
+                                          cacerts, ncacerts, cacertFile,
                                           isServer, errp) < 0) {
         goto cleanup;
     }
@@ -573,8 +556,8 @@ qcrypto_tls_creds_x509_sanity_check(QCryptoTLSCredsX509 *creds,
     ret = 0;
 
  cleanup:
-    if (cert) {
-        gnutls_x509_crt_deinit(cert);
+    for (i = 0; i < ncerts; i++) {
+        gnutls_x509_crt_deinit(certs[i]);
     }
     for (i = 0; i < ncacerts; i++) {
         gnutls_x509_crt_deinit(cacerts[i]);

diff --git a/tests/unit/test-crypto-tlscredsx509.c b/tests/unit/test-crypto-tlscredsx509.c
index 7c5df32bccfcbb6df587c8865a4d1783e783f25a..96ad4e741bbfd7472b58ad3c7ee223385872bf19 100644 (file)
--- a/tests/unit/test-crypto-tlscredsx509.c
+++ b/tests/unit/test-crypto-tlscredsx509.c
@@ -580,6 +580,12 @@ int main(int argc, char **argv)
                  true, true, GNUTLS_KEY_KEY_CERT_SIGN,
                  false, false, NULL, NULL,
                  0, 0);
+    TLS_ROOT_REQ(someotherrootreq,
+                 "UK", "some other random CA", NULL, NULL, NULL, NULL,
+                 true, true, true,
+                 true, true, GNUTLS_KEY_KEY_CERT_SIGN,
+                 false, false, NULL, NULL,
+                 0, 0);
     TLS_CERT_REQ(cacertlevel1areq, cacertrootreq,
                  "UK", "qemu level 1a", NULL, NULL, NULL, NULL,
                  true, true, true,
@@ -626,6 +632,32 @@ int main(int argc, char **argv)
         cacertlevel2areq.crt,
     };
 
+    gnutls_x509_crt_t cabundle[] = {
+        someotherrootreq.crt,
+        cacertrootreq.crt,
+    };
+
+    gnutls_x509_crt_t servercertchain[] = {
+        servercertlevel3areq.crt,
+        cacertlevel2areq.crt,
+        cacertlevel1areq.crt,
+    };
+
+    gnutls_x509_crt_t servercertchain_incomplete[] = {
+        servercertlevel3areq.crt,
+        cacertlevel2areq.crt,
+    };
+
+    gnutls_x509_crt_t servercertchain_unsorted[] = {
+        servercertlevel3areq.crt,
+        cacertlevel1areq.crt,
+        cacertlevel2areq.crt,
+    };
+
+    gnutls_x509_crt_t clientcertchain[] = {
+        clientcertlevel2breq.crt,
+        cacertlevel1breq.crt,
+    };
 
     test_tls_write_cert_chain(WORKDIR "cacertchain-ctx.pem",
                               certchain,
@@ -665,6 +697,46 @@ int main(int argc, char **argv)
                  WORKDIR "cacertchain-incomplete-ctx.pem",
                  servercertlevel3areq.filename, true);
 
+    test_tls_write_cert_chain(WORKDIR "servercertchain-ctx.pem",
+                              servercertchain,
+                              G_N_ELEMENTS(servercertchain));
+
+    TLS_TEST_REG(serverchain, true,
+                 cacertrootreq.filename,
+                 WORKDIR "servercertchain-ctx.pem", false);
+
+    test_tls_write_cert_chain(WORKDIR "cabundle-ctx.pem",
+                              cabundle,
+                              G_N_ELEMENTS(cabundle));
+
+    TLS_TEST_REG(multiplecaswithchain, true,
+                 WORKDIR "cabundle-ctx.pem",
+                 WORKDIR "servercertchain-ctx.pem", false);
+
+    test_tls_write_cert_chain(WORKDIR "servercertchain_incomplete-ctx.pem",
+                              servercertchain_incomplete,
+                              G_N_ELEMENTS(servercertchain_incomplete));
+
+    TLS_TEST_REG(incompleteserverchain, true,
+                 cacertrootreq.filename,
+                 WORKDIR "servercertchain_incomplete-ctx.pem", true);
+
+    test_tls_write_cert_chain(WORKDIR "servercertchain_unsorted-ctx.pem",
+                              servercertchain_unsorted,
+                              G_N_ELEMENTS(servercertchain_unsorted));
+
+    TLS_TEST_REG(unsortedserverchain, true,
+                 cacertrootreq.filename,
+                 WORKDIR "servercertchain_unsorted-ctx.pem", true);
+
+    test_tls_write_cert_chain(WORKDIR "clientcertchain-ctx.pem",
+                              clientcertchain,
+                              G_N_ELEMENTS(clientcertchain));
+
+    TLS_TEST_REG(clientchain, false,
+                 cacertrootreq.filename,
+                 WORKDIR "clientcertchain-ctx.pem", false);
+
     /* Some missing certs - first two are fatal, the last
      * is ok
      */
@@ -734,8 +806,13 @@ int main(int argc, char **argv)
     test_tls_discard_cert(&cacertlevel2areq);
     test_tls_discard_cert(&servercertlevel3areq);
     test_tls_discard_cert(&clientcertlevel2breq);
+    test_tls_discard_cert(&someotherrootreq);
     unlink(WORKDIR "cacertchain-ctx.pem");
     unlink(WORKDIR "cacertchain-with-invalid-ctx.pem");
+    unlink(WORKDIR "servercertchain-ctx.pem");
+    unlink(WORKDIR "servercertchain_incomplete-ctx.pem");
+    unlink(WORKDIR "servercertchain_unsorted-ctx.pem");
+    unlink(WORKDIR "clientcertchain-ctx.pem");
 
     test_tls_cleanup(KEYFILE);
     rmdir(WORKDIR);