Add NegoEx tests

Add a mock NegoEx-only GSS module, a test program which establishes a
SPNEGO context, and a Python script to exercise a variety of NegoEx
negotiation scenarios.

ticket: 8851

11 files changed, 623 insertions, 21 deletions

diff --git a/.gitignore b/.gitignore
index bc15f78..adf6615 100644
--- a/.gitignore
+++ b/.gitignore
@@ -474,6 +474,7 @@ local.properties
 /src/tests/gssapi/t_add_cred
 /src/tests/gssapi/t_ccselect
 /src/tests/gssapi/t_ciflags
+/src/tests/gssapi/t_context
 /src/tests/gssapi/t_credstore
 /src/tests/gssapi/t_enctypes
 /src/tests/gssapi/t_err
diff --git a/src/Makefile.in b/src/Makefile.in
index 691f86c..56c7a4e 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -13,6 +13,7 @@ SUBDIRS=util include lib \
 	@audit_plugin@ \
 	plugins/kadm5_hook/test \
 	plugins/kadm5_auth/test \
+	plugins/gssapi/negoextest \
 	plugins/hostrealm/test \
 	plugins/localauth/test \
 	plugins/pwqual/test \
diff --git a/src/configure.ac b/src/configure.ac
index 171bad4..79b0bd0 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -1499,6 +1499,7 @@ V5_AC_OUTPUT_MAKEFILE(.
 	kdc kprop config-files build-tools man doc include
 
 	plugins/certauth/test
+	plugins/gssapi/negoextest
 	plugins/hostrealm/test
 	plugins/localauth/test
 	plugins/kadm5_hook/test
diff --git a/src/plugins/gssapi/negoextest/Makefile.in b/src/plugins/gssapi/negoextest/Makefile.in
new file mode 100644
index 0000000..62e8a37
--- /dev/null
+++ b/src/plugins/gssapi/negoextest/Makefile.in
@@ -0,0 +1,20 @@
+mydir=plugins$(S)gssapi$(S)negoextest
+BUILDTOP=$(REL)..$(S)..$(S)..
+
+LIBBASE=gss_negoextest
+LIBMAJOR=0
+LIBMINOR=0
+RELDIR=../plugins/gssapi/negoextest
+SHLIB_EXPDEPS=$(GSS_DEPLIBS) $(KRB5_BASE_DEPLIBS)
+SHLIB_EXPLIBS=$(GSS_LIBS) $(KRB5_BASE_LIBS)
+
+STLIBOBJS=main.o
+
+SRCS=$(srcdir)/main.c
+
+all-unix: all-libs
+install-unix:
+clean-unix:: clean-libs clean-libobjs
+
+@libnover_frag@
+@libobj_frag@
diff --git a/src/plugins/gssapi/negoextest/deps b/src/plugins/gssapi/negoextest/deps
new file mode 100644
index 0000000..1e18ff4
--- /dev/null
+++ b/src/plugins/gssapi/negoextest/deps
@@ -0,0 +1,15 @@
+#
+# Generated makefile dependencies follow.
+#
+main.so main.po $(OUTPRE)main.$(OBJEXT): $(BUILDTOP)/include/autoconf.h \
+  $(BUILDTOP)/include/gssapi/gssapi.h $(BUILDTOP)/include/gssapi/gssapi_alloc.h \
+  $(BUILDTOP)/include/gssapi/gssapi_ext.h $(BUILDTOP)/include/krb5/krb5.h \
+  $(BUILDTOP)/include/osconf.h $(BUILDTOP)/include/profile.h \
+  $(COM_ERR_DEPS) $(top_srcdir)/include/k5-buf.h $(top_srcdir)/include/k5-err.h \
+  $(top_srcdir)/include/k5-gmt_mktime.h $(top_srcdir)/include/k5-int-pkinit.h \
+  $(top_srcdir)/include/k5-int.h $(top_srcdir)/include/k5-platform.h \
+  $(top_srcdir)/include/k5-plugin.h $(top_srcdir)/include/k5-thread.h \
+  $(top_srcdir)/include/k5-trace.h $(top_srcdir)/include/krb5.h \
+  $(top_srcdir)/include/krb5/authdata_plugin.h $(top_srcdir)/include/krb5/plugin.h \
+  $(top_srcdir)/include/port-sockets.h $(top_srcdir)/include/socket-utils.h \
+  main.c
diff --git a/src/plugins/gssapi/negoextest/gss_negoextest.exports b/src/plugins/gssapi/negoextest/gss_negoextest.exports
new file mode 100644
index 0000000..7825ab1
--- /dev/null
+++ b/src/plugins/gssapi/negoextest/gss_negoextest.exports
@@ -0,0 +1,13 @@
+gss_accept_sec_context
+gss_acquire_cred
+gss_acquire_cred_with_password
+gss_delete_sec_context
+gss_display_status
+gss_import_name
+gss_init_sec_context
+gss_inquire_sec_context_by_oid
+gss_release_cred
+gss_release_name
+gssspi_exchange_meta_data
+gssspi_query_mechanism_info
+gssspi_query_meta_data
diff --git a/src/plugins/gssapi/negoextest/main.c b/src/plugins/gssapi/negoextest/main.c
new file mode 100644
index 0000000..6c340f4
--- /dev/null
+++ b/src/plugins/gssapi/negoextest/main.c
@@ -0,0 +1,340 @@
+/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/* plugins/gssapi/negoextest/main.c - GSS test module for NegoEx */
+/*
+ * Copyright (C) 2019 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in
+ *   the documentation and/or other materials provided with the
+ *   distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "k5-int.h"
+#include <gssapi/gssapi.h>
+#include <gssapi/gssapi_ext.h>
+#include <gssapi/gssapi_alloc.h>
+
+struct test_context {
+    int initiator;
+    uint8_t hops;               /* hops remaining; 0 means established */
+};
+
+OM_uint32 KRB5_CALLCONV
+gss_init_sec_context(OM_uint32 *minor_status,
+                     gss_cred_id_t claimant_cred_handle,
+                     gss_ctx_id_t *context_handle, gss_name_t target_name,
+                     gss_OID mech_type, OM_uint32 req_flags,
+                     OM_uint32 time_req,
+                     gss_channel_bindings_t input_chan_bindings,
+                     gss_buffer_t input_token, gss_OID *actual_mech,
+                     gss_buffer_t output_token, OM_uint32 *ret_flags,
+                     OM_uint32 *time_rec)
+{
+    struct test_context *ctx = (struct test_context *)*context_handle;
+    OM_uint32 major;
+    gss_buffer_desc tok;
+    const char *envstr;
+    uint8_t hops, mech_last_octet;
+
+    if (input_token == GSS_C_NO_BUFFER || input_token->length == 0) {
+        envstr = getenv("HOPS");
+        hops = (envstr != NULL) ? atoi(envstr) : 1;
+        assert(hops > 0);
+    } else if (input_token->length == 4 &&
+               memcmp(input_token->value, "fail", 4) == 0) {
+        *minor_status = 12345;
+        return GSS_S_FAILURE;
+    } else {
+        hops = ((uint8_t *)input_token->value)[0];
+    }
+
+    mech_last_octet = ((uint8_t *)mech_type->elements)[mech_type->length - 1];
+    envstr = getenv("INIT_FAIL");
+    if (envstr != NULL && atoi(envstr) == mech_last_octet)
+        return GSS_S_FAILURE;
+
+    if (ctx == NULL) {
+        ctx = malloc(sizeof(*ctx));
+        assert(ctx != NULL);
+        ctx->initiator = 1;
+        ctx->hops = hops;
+        *context_handle = (gss_ctx_id_t)ctx;
+    } else if (ctx != NULL) {
+        assert(ctx->initiator);
+        ctx->hops--;
+        assert(ctx->hops == hops);
+    }
+
+    if (ctx->hops > 0) {
+        /* Generate a token containing the remaining hop count. */
+        ctx->hops--;
+        tok.value = &ctx->hops;
+        tok.length = 1;
+        major = gss_encapsulate_token(&tok, mech_type, output_token);
+        assert(major == GSS_S_COMPLETE);
+    }
+
+    return (ctx->hops > 0) ? GSS_S_CONTINUE_NEEDED : GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_accept_sec_context(OM_uint32 *minor_status, gss_ctx_id_t *context_handle,
+                       gss_cred_id_t verifier_cred_handle,
+                       gss_buffer_t input_token,
+                       gss_channel_bindings_t input_chan_bindings,
+                       gss_name_t *src_name, gss_OID *mech_type,
+                       gss_buffer_t output_token, OM_uint32 *ret_flags,
+                       OM_uint32 *time_rec,
+                       gss_cred_id_t *delegated_cred_handle)
+{
+    struct test_context *ctx = (struct test_context *)*context_handle;
+    uint8_t hops, mech_last_octet;
+    const char *envstr;
+
+    /*
+     * The unwrapped token sits at the end and is just one byte giving the
+     * remaining number of hops.  The final octet of the mech encoding should
+     * be just prior to it.
+     */
+    assert(input_token->length >= 2);
+    hops = ((uint8_t *)input_token->value)[input_token->length - 1];
+    mech_last_octet = ((uint8_t *)input_token->value)[input_token->length - 2];
+
+    envstr = getenv("ACCEPT_FAIL");
+    if (envstr != NULL && atoi(envstr) == mech_last_octet) {
+        output_token->value = gssalloc_strdup("fail");
+        assert(output_token->value != NULL);
+        output_token->length = 4;
+        return GSS_S_FAILURE;
+    }
+
+    if (*context_handle == GSS_C_NO_CONTEXT) {
+        ctx = malloc(sizeof(*ctx));
+        assert(ctx != NULL);
+        ctx->initiator = 0;
+        ctx->hops = hops;
+        *context_handle = (gss_ctx_id_t)ctx;
+    } else {
+        assert(!ctx->initiator);
+        ctx->hops--;
+        assert(ctx->hops == hops);
+    }
+
+    if (ctx->hops > 0) {
+        /* Generate a token containing the remaining hop count. */
+        ctx->hops--;
+        output_token->value = gssalloc_malloc(1);
+        assert(output_token->value != NULL);
+        memcpy(output_token->value, &ctx->hops, 1);
+        output_token->length = 1;
+    }
+
+    return (ctx->hops > 0) ? GSS_S_CONTINUE_NEEDED : GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_delete_sec_context(OM_uint32 *minor_status, gss_ctx_id_t *context_handle,
+                       gss_buffer_t output_token)
+{
+    free(*context_handle);
+    *context_handle = GSS_C_NO_CONTEXT;
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_acquire_cred(OM_uint32 *minor_status, gss_name_t desired_name,
+                 OM_uint32 time_req, gss_OID_set desired_mechs,
+                 gss_cred_usage_t cred_usage,
+                 gss_cred_id_t *output_cred_handle, gss_OID_set *actual_mechs,
+                 OM_uint32 *time_rec)
+{
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_acquire_cred_with_password(OM_uint32 *minor_status,
+                               const gss_name_t desired_name,
+                               const gss_buffer_t password, OM_uint32 time_req,
+                               const gss_OID_set desired_mechs,
+                               gss_cred_usage_t cred_usage,
+                               gss_cred_id_t *output_cred_handle,
+                               gss_OID_set *actual_mechs, OM_uint32 *time_rec)
+{
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_release_cred(OM_uint32 *minor_status, gss_cred_id_t *cred_handle)
+{
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_import_name(OM_uint32 *minor_status, gss_buffer_t input_name_buffer,
+                gss_OID input_name_type, gss_name_t *output_name)
+{
+    static int dummy;
+
+    /*
+     * We don't need to remember anything about names, but we do need to
+     * distinguish them from GSS_C_NO_NAME (to determine the direction of
+     * gss_query_meta_data() and gss_exchange_meta_data()), so assign an
+     * arbitrary data pointer.
+     */
+    *output_name = (gss_name_t)&dummy;
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_release_name(OM_uint32 *minor_status, gss_name_t *input_name)
+{
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_display_status(OM_uint32 *minor_status, OM_uint32 status_value,
+                   int status_type, gss_OID mech_type,
+                   OM_uint32 *message_context, gss_buffer_t status_string)
+{
+    if (status_type == GSS_C_MECH_CODE && status_value == 12345) {
+        status_string->value = gssalloc_strdup("failure from acceptor");
+        assert(status_string->value != NULL);
+        status_string->length = strlen(status_string->value);
+        return GSS_S_COMPLETE;
+    }
+    return GSS_S_BAD_STATUS;
+}
+
+OM_uint32 KRB5_CALLCONV
+gssspi_query_meta_data(OM_uint32 *minor_status, gss_const_OID mech_oid,
+                       gss_cred_id_t cred_handle, gss_ctx_id_t *context_handle,
+                       const gss_name_t targ_name, OM_uint32 req_flags,
+                       gss_buffer_t meta_data)
+{
+    const char *envstr;
+    uint8_t mech_last_octet;
+    int initiator = (targ_name != GSS_C_NO_NAME);
+
+    mech_last_octet = ((uint8_t *)mech_oid->elements)[mech_oid->length - 1];
+    envstr = getenv(initiator ? "INIT_QUERY_FAIL" : "ACCEPT_QUERY_FAIL");
+    if (envstr != NULL && atoi(envstr) == mech_last_octet)
+        return GSS_S_FAILURE;
+    envstr = getenv(initiator ? "INIT_QUERY_NONE" : "ACCEPT_QUERY_NONE");
+    if (envstr != NULL && atoi(envstr) == mech_last_octet)
+        return GSS_S_COMPLETE;
+
+    meta_data->value = gssalloc_strdup("X");
+    meta_data->length = 1;
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gssspi_exchange_meta_data(OM_uint32 *minor_status, gss_const_OID mech_oid,
+                          gss_cred_id_t cred_handle,
+                          gss_ctx_id_t *context_handle,
+                          const gss_name_t targ_name, OM_uint32 req_flags,
+                          gss_const_buffer_t meta_data)
+{
+    const char *envstr;
+    uint8_t mech_last_octet;
+    int initiator = (targ_name != GSS_C_NO_NAME);
+
+    mech_last_octet = ((uint8_t *)mech_oid->elements)[mech_oid->length - 1];
+    envstr = getenv(initiator ? "INIT_EXCHANGE_FAIL" : "ACCEPT_EXCHANGE_FAIL");
+    if (envstr != NULL && atoi(envstr) == mech_last_octet)
+        return GSS_S_FAILURE;
+
+    assert(meta_data->length == 1 && memcmp(meta_data->value, "X", 1) == 0);
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gssspi_query_mechanism_info(OM_uint32 *minor_status, gss_const_OID mech_oid,
+                            unsigned char auth_scheme[16])
+{
+    /* Copy the mech OID encoding and right-pad it with zeros. */
+    memset(auth_scheme, 0, 16);
+    assert(mech_oid->length <= 16);
+    memcpy(auth_scheme, mech_oid->elements, mech_oid->length);
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32 KRB5_CALLCONV
+gss_inquire_sec_context_by_oid(OM_uint32 *minor_status,
+                               const gss_ctx_id_t context_handle,
+                               const gss_OID desired_object,
+                               gss_buffer_set_t *data_set)
+{
+    struct test_context *ctx = (struct test_context *)context_handle;
+    OM_uint32 major;
+    uint8_t keybytes[32] = { 0 };
+    uint8_t typebytes[4];
+    gss_buffer_desc key, type;
+    const char *envstr;
+    int ask_verify;
+
+    if (gss_oid_equal(desired_object, GSS_C_INQ_NEGOEX_KEY))
+        ask_verify = 0;
+    else if (gss_oid_equal(desired_object, GSS_C_INQ_NEGOEX_VERIFY_KEY))
+        ask_verify = 1;
+    else
+        return GSS_S_UNAVAILABLE;
+
+    /*
+     * By default, make a key available only if the context is established.
+     * This can be overridden to "always", "init-always", "accept-always",
+     * or "never".
+     */
+    envstr = getenv("KEY");
+    if (envstr != NULL && strcmp(envstr, "never") == 0) {
+        return GSS_S_UNAVAILABLE;
+    } else if (ctx->hops > 0) {
+        if (envstr == NULL)
+            return GSS_S_UNAVAILABLE;
+        else if (strcmp(envstr, "init-always") == 0 && !ctx->initiator)
+            return GSS_S_UNAVAILABLE;
+        else if (strcmp(envstr, "accept-always") == 0 && ctx->initiator)
+            return GSS_S_UNAVAILABLE;
+    }
+
+    /* Perturb the key so that each side's verifier key is equal to the other's
+     * checksum key. */
+    keybytes[0] = ask_verify ^ ctx->initiator;
+
+    /* Supply an all-zeros aes256-sha1 negoex key. */
+    if (gss_oid_equal(desired_object, GSS_C_INQ_NEGOEX_KEY) ||
+        gss_oid_equal(desired_object, GSS_C_INQ_NEGOEX_VERIFY_KEY)) {
+        store_32_le(ENCTYPE_AES256_CTS_HMAC_SHA1_96, typebytes);
+        key.value = keybytes;
+        key.length = sizeof(keybytes);
+        type.value = typebytes;
+        type.length = sizeof(typebytes);
+        major = gss_add_buffer_set_member(minor_status, &key, data_set);
+        if (major != GSS_S_COMPLETE)
+            return major;
+        return gss_add_buffer_set_member(minor_status, &type, data_set);
+    }
+
+    return GSS_S_UNAVAILABLE;
+}
diff --git a/src/tests/gssapi/Makefile.in b/src/tests/gssapi/Makefile.in
index a7b8da4..5cc1e0f 100644
--- a/src/tests/gssapi/Makefile.in
+++ b/src/tests/gssapi/Makefile.in
@@ -10,10 +10,11 @@ LOCALINCLUDES = -I$(srcdir)/../../lib/gssapi/mechglue \
 
 SRCS=	$(srcdir)/ccinit.c $(srcdir)/ccrefresh.c $(srcdir)/common.c \
 	$(srcdir)/t_accname.c $(srcdir)/t_add_cred.c $(srcdir)/t_ccselect.c \
-	$(srcdir)/t_ciflags.c $(srcdir)/t_credstore.c $(srcdir)/t_enctypes.c \
-	$(srcdir)/t_err.c $(srcdir)/t_export_cred.c $(srcdir)/t_export_name.c \
-	$(srcdir)/t_gssexts.c $(srcdir)/t_imp_cred.c $(srcdir)/t_imp_name.c \
-	$(srcdir)/t_invalid.c $(srcdir)/t_inq_cred.c $(srcdir)/t_inq_ctx.c \
+	$(srcdir)/t_ciflags.c $(srcdir)/t_context.c $(srcdir)/t_credstore.c \
+	$(srcdir)/t_enctypes.c $(srcdir)/t_err.c $(srcdir)/t_export_cred.c \
+	$(srcdir)/t_export_name.c $(srcdir)/t_gssexts.c \
+	$(srcdir)/t_imp_cred.c $(srcdir)/t_imp_name.c $(srcdir)/t_invalid.c \
+	$(srcdir)/t_inq_cred.c $(srcdir)/t_inq_ctx.c \
 	$(srcdir)/t_inq_mechs_name.c $(srcdir)/t_iov.c \
 	$(srcdir)/t_lifetime.c $(srcdir)/t_namingexts.c $(srcdir)/t_oid.c \
 	$(srcdir)/t_pcontok.c $(srcdir)/t_prf.c $(srcdir)/t_s4u.c \
@@ -21,20 +22,20 @@ SRCS=	$(srcdir)/ccinit.c $(srcdir)/ccrefresh.c $(srcdir)/common.c \
 	$(srcdir)/t_spnego.c $(srcdir)/t_srcattrs.c
 
 OBJS=	ccinit.o ccrefresh.o common.o t_accname.o t_add_cred.o t_ccselect.o \
-	t_ciflags.o t_credstore.o t_enctypes.o t_err.o t_export_cred.o \
-	t_export_name.o t_gssexts.o t_imp_cred.o t_imp_name.o t_invalid.o \
-	t_inq_cred.o t_inq_ctx.o t_inq_mechs_name.o t_iov.o t_lifetime.o \
-	t_namingexts.o t_oid.o t_pcontok.o t_prf.o t_s4u.o t_s4u2proxy_krb5.o \
-	t_saslname.o t_spnego.o t_srcattrs.o
+	t_ciflags.o t_context.o t_credstore.o t_enctypes.o t_err.o \
+	t_export_cred.o t_export_name.o t_gssexts.o t_imp_cred.o t_imp_name.o \
+	t_invalid.o t_inq_cred.o t_inq_ctx.o t_inq_mechs_name.o t_iov.o \
+	t_lifetime.o t_namingexts.o t_oid.o t_pcontok.o t_prf.o t_s4u.o \
+	t_s4u2proxy_krb5.o t_saslname.o t_spnego.o t_srcattrs.o
 
 COMMON_DEPS= common.o $(GSS_DEPLIBS) $(KRB5_BASE_DEPLIBS)
 COMMON_LIBS= common.o $(GSS_LIBS) $(KRB5_BASE_LIBS)
 
-all: ccinit ccrefresh t_accname t_add_cred t_ccselect t_ciflags t_credstore \
-	t_enctypes t_err t_export_cred t_export_name t_gssexts t_imp_cred \
-	t_imp_name t_invalid t_inq_cred t_inq_ctx t_inq_mechs_name t_iov \
-	t_lifetime t_namingexts t_oid t_pcontok t_prf t_s4u t_s4u2proxy_krb5 \
-	t_saslname t_spnego t_srcattrs
+all: ccinit ccrefresh t_accname t_add_cred t_ccselect t_ciflags t_context \
+	t_credstore t_enctypes t_err t_export_cred t_export_name t_gssexts \
+	t_imp_cred t_imp_name t_invalid t_inq_cred t_inq_ctx t_inq_mechs_name \
+	t_iov t_lifetime t_namingexts t_oid t_pcontok t_prf t_s4u \
+	t_s4u2proxy_krb5 t_saslname t_spnego t_srcattrs
 
 check-unix: t_oid
 	$(RUN_TEST) ./t_invalid
@@ -43,9 +44,9 @@ check-unix: t_oid
 	$(RUN_TEST) ./t_imp_name
 
 check-pytests: ccinit ccrefresh t_accname t_add_cred t_ccselect t_ciflags \
-	t_credstore t_enctypes t_err t_export_cred t_export_name t_imp_cred \
-	t_inq_cred t_inq_ctx t_inq_mechs_name t_iov t_lifetime t_pcontok \
-	t_s4u t_s4u2proxy_krb5 t_spnego t_srcattrs
+	t_context t_credstore t_enctypes t_err t_export_cred t_export_name \
+	t_imp_cred t_inq_cred t_inq_ctx t_inq_mechs_name t_iov t_lifetime \
+	t_pcontok t_s4u t_s4u2proxy_krb5 t_spnego t_srcattrs
 	$(RUNPYTEST) $(srcdir)/t_gssapi.py $(PYTESTFLAGS)
 	$(RUNPYTEST) $(srcdir)/t_ccselect.py $(PYTESTFLAGS)
 	$(RUNPYTEST) $(srcdir)/t_client_keytab.py $(PYTESTFLAGS)
@@ -53,6 +54,7 @@ check-pytests: ccinit ccrefresh t_accname t_add_cred t_ccselect t_ciflags \
 	$(RUNPYTEST) $(srcdir)/t_export_cred.py $(PYTESTFLAGS)
 	$(RUNPYTEST) $(srcdir)/t_s4u.py $(PYTESTFLAGS)
 	$(RUNPYTEST) $(srcdir)/t_authind.py $(PYTESTFLAGS)
+	$(RUNPYTEST) $(srcdir)/t_negoex.py $(PYTESTFLAGS)
 
 ccinit: ccinit.o $(KRB5_BASE_DEPLIBS)
 	$(CC_LINK) -o ccinit ccinit.o $(KRB5_BASE_LIBS)
@@ -66,6 +68,8 @@ t_ccselect: t_ccselect.o $(COMMON_DEPS)
 	$(CC_LINK) -o $@ t_ccselect.o $(COMMON_LIBS)
 t_ciflags: t_ciflags.o $(COMMON_DEPS)
 	$(CC_LINK) -o $@ t_ciflags.o $(COMMON_LIBS)
+t_context: t_context.o $(COMMON_DEPS)
+	$(CC_LINK) -o $@ t_context.o $(COMMON_LIBS)
 t_credstore: t_credstore.o $(COMMON_DEPS)
 	$(CC_LINK) -o $@ t_credstore.o $(COMMON_LIBS)
 t_enctypes: t_enctypes.o $(COMMON_DEPS)
@@ -115,7 +119,8 @@ t_srcattrs: t_srcattrs.o $(COMMON_DEPS)
 
 clean:
 	$(RM) ccinit ccrefresh t_accname t_add_cred t_ccselect t_ciflags
-	$(RM) t_credstore t_enctypes t_err t_export_cred t_export_name
-	$(RM) t_gssexts t_imp_cred t_imp_name t_invalid t_inq_cred t_inq_ctx
-	$(RM) t_inq_mechs_name t_iov t_lifetime t_namingexts t_oid t_pcontok
-	$(RM) t_prf t_s4u t_s4u2proxy_krb5 t_saslname t_spnego t_srcattrs
+	$(RM) t_context t_credstore t_enctypes t_err t_export_cred
+	$(RM) t_export_name t_gssexts t_imp_cred t_imp_name t_invalid
+	$(RM) t_inq_cred t_inq_ctx t_inq_mechs_name t_iov t_lifetime
+	$(RM) t_namingexts t_oid t_pcontok t_prf t_s4u t_s4u2proxy_krb5
+	$(RM) t_saslname t_spnego t_srcattrs
diff --git a/src/tests/gssapi/deps b/src/tests/gssapi/deps
index c8905c9..acd0e96 100644
--- a/src/tests/gssapi/deps
+++ b/src/tests/gssapi/deps
@@ -41,6 +41,10 @@ $(OUTPRE)t_ciflags.$(OBJEXT): $(BUILDTOP)/include/gssapi/gssapi.h \
   $(BUILDTOP)/include/gssapi/gssapi_ext.h $(BUILDTOP)/include/gssapi/gssapi_krb5.h \
   $(BUILDTOP)/include/krb5/krb5.h $(COM_ERR_DEPS) $(top_srcdir)/include/krb5.h \
   common.h t_ciflags.c
+$(OUTPRE)t_context.$(OBJEXT): $(BUILDTOP)/include/gssapi/gssapi.h \
+  $(BUILDTOP)/include/gssapi/gssapi_ext.h $(BUILDTOP)/include/gssapi/gssapi_krb5.h \
+  $(BUILDTOP)/include/krb5/krb5.h $(COM_ERR_DEPS) $(top_srcdir)/include/krb5.h \
+  common.h t_context.c
 $(OUTPRE)t_credstore.$(OBJEXT): $(BUILDTOP)/include/gssapi/gssapi.h \
   $(BUILDTOP)/include/gssapi/gssapi_ext.h $(BUILDTOP)/include/gssapi/gssapi_krb5.h \
   $(BUILDTOP)/include/krb5/krb5.h $(COM_ERR_DEPS) $(top_srcdir)/include/krb5.h \
diff --git a/src/tests/gssapi/t_context.c b/src/tests/gssapi/t_context.c
new file mode 100644
index 0000000..65381ac
--- /dev/null
+++ b/src/tests/gssapi/t_context.c
@@ -0,0 +1,60 @@
+/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/* tests/gssapi/t_context.c - Simple context establishment harness */
+/*
+ * Copyright (C) 2019 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in
+ *   the documentation and/or other materials provided with the
+ *   distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "common.h"
+
+int
+main(int argc, char *argv[])
+{
+    OM_uint32 minor, flags;
+    gss_name_t tname;
+    gss_ctx_id_t ictx, actx;
+
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s targetname [acceptorname]\n", argv[0]);
+        return 1;
+    }
+
+    tname = import_name(argv[1]);
+
+    flags = GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG;
+    establish_contexts(&mech_spnego, GSS_C_NO_CREDENTIAL, GSS_C_NO_CREDENTIAL,
+                       tname, flags, &ictx, &actx, NULL, NULL, NULL);
+
+    (void)gss_release_name(&minor, &tname);
+    (void)gss_delete_sec_context(&minor, &ictx, NULL);
+    (void)gss_delete_sec_context(&minor, &actx, NULL);
+    return 0;
+}
diff --git a/src/tests/gssapi/t_negoex.py b/src/tests/gssapi/t_negoex.py
new file mode 100644
index 0000000..88470d2
--- /dev/null
+++ b/src/tests/gssapi/t_negoex.py
@@ -0,0 +1,142 @@
+from k5test import *
+
+# The next arc after 2.25 is supposed to be a single-integer UUID, but
+# since our gss_str_to_oid() can't handle arc values that don't fit in
+# an unsigned long, we use random unsigned 32-bit integers instead.
+# The final octet if the OID encoding will be used to identify the
+# mechanism when changing the behavior of just one mech.
+nxtest_oid1 = '2.25.1414534758' # final octet is 102 (0x66)
+nxtest_oid2 = '2.25.1175737388' # final octet is 44 (0x2C)
+nxtest_path = os.path.join(buildtop, 'plugins', 'gssapi', 'negoextest',
+                           'gss_negoextest.so')
+
+# Test gss_add_cred().
+realm = K5Realm(create_kdb=False)
+with open(realm.gss_mech_config, 'w') as f:
+    f.write('negoextest %s %s\n' % (nxtest_oid1, nxtest_path))
+    f.write('negoextest %s %s\n' % (nxtest_oid2, nxtest_path))
+
+def test(envvars, **kw):
+    # Python 3.5: e = {**realm.env, **vars}
+    e = realm.env.copy()
+    e.update(envvars)
+    realm.run(['./t_context', 'h:host'], env=e, **kw)
+
+# Test varying numbers of hops, and spot-check that messages are sent
+# in the appropriate sequence.
+
+mark('One hop')
+msgs = ('sending [0]INITIATOR_NEGO: c0a28569-66ac-0000-0000-000000000000 '
+        'd1b08469-2ca8-0000-0000-000000000000',
+        'sending [1]INITIATOR_META_DATA: c0a28569-66ac',
+        'sending [2]INITIATOR_META_DATA: d1b08469-2ca8',
+        'sending [3]AP_REQUEST: c0a28569-66ac',
+        'sending [4]VERIFY: c0a28569-66ac',
+        'received [0]INITIATOR_NEGO: c0a28569-66ac-0000-0000-000000000000 '
+        'd1b08469-2ca8-0000-0000-000000000000',
+        'received [1]INITIATOR_META_DATA: c0a28569-66ac',
+        'received [2]INITIATOR_META_DATA: d1b08469-2ca8',
+        'received [3]AP_REQUEST: c0a28569-66ac',
+        'received [4]VERIFY: c0a28569-66ac',
+        'sending [5]ACCEPTOR_NEGO: c0a28569-66ac-0000-0000-000000000000 '
+        'd1b08469-2ca8-0000-0000-000000000000',
+        'sending [6]ACCEPTOR_META_DATA: c0a28569-66ac',
+        'sending [7]ACCEPTOR_META_DATA: d1b08469-2ca8',
+        'sending [8]VERIFY: c0a28569-66ac',
+        'received [5]ACCEPTOR_NEGO: c0a28569-66ac-0000-0000-000000000000 '
+        'd1b08469-2ca8-0000-0000-000000000000',
+        'received [6]ACCEPTOR_META_DATA: c0a28569-66ac',
+        'received [7]ACCEPTOR_META_DATA: d1b08469-2ca8',
+        'received [8]VERIFY: c0a28569-66ac')
+test({'HOPS': '1'}, expected_trace=msgs)
+
+mark('Two hops')
+msgs = ('sending [7]CHALLENGE', 'sending [8]VERIFY', 'received [8]VERIFY',
+        'sending [9]VERIFY')
+test({'HOPS': '2'}, expected_trace=msgs)
+
+mark('Three hops')
+msgs = ('sending [8]AP_REQUEST', 'sending [9]VERIFY', 'received [8]AP_REQUEST',
+        'sending [10]VERIFY')
+test({'HOPS': '3'}, expected_trace=msgs)
+
+mark('Four hops')
+msgs = ('sending [9]CHALLENGE', 'sending [10]VERIFY', 'received [9]CHALLENGE',
+        'sending [11]VERIFY')
+test({'HOPS': '4'}, expected_trace=msgs)
+
+mark('Early keys, three hops')
+msgs = ('sending [4]VERIFY', 'sending [9]VERIFY', 'sending [10]AP_REQUEST')
+test({'HOPS': '3', 'KEY': 'always'}, expected_trace=msgs)
+
+mark('Early keys, four hops')
+msgs = ('sending [4]VERIFY', 'sending [9]VERIFY', 'sending [10]AP_REQUEST',
+        'sending [11]CHALLENGE')
+test({'HOPS': '4', 'KEY': 'always'}, expected_trace=msgs)
+
+mark('No keys')
+test({'KEY': 'never'}, expected_code=1, expected_msg='No NegoEx verify key')
+
+mark('No optimistic token')
+msgs = ('sending [3]ACCEPTOR_NEGO', 'sending [6]AP_REQUEST',
+        'sending [7]VERIFY', 'sending [8]VERIFY')
+test({'NEGOEX_NO_OPTIMISTIC_TOKEN': ''}, expected_trace=msgs)
+
+mark('First mech initiator query fail')
+msgs = ('sending [0]INITIATOR_NEGO: d1b08469-2ca8-0000-0000-000000000000',
+        'sending [2]AP_REQUEST', 'sending [3]VERIFY',
+        'sending [4]ACCEPTOR_NEGO: d1b08469-2ca8-0000-0000-000000000000',
+        'sending [6]VERIFY')
+test({'INIT_QUERY_FAIL': '102'}, expected_trace=msgs)
+
+mark('First mech acceptor query fail')
+msgs = ('sending [0]INITIATOR_NEGO: c0a28569-66ac-0000-0000-000000000000 '
+        'd1b08469-2ca8-0000-0000-000000000000',
+        'sending [3]AP_REQUEST: c0a28569-66ac',
+        'sending [4]VERIFY: c0a28569-66ac',
+        'sending [5]ACCEPTOR_NEGO: d1b08469-2ca8-0000-0000-000000000000',
+        'sending [7]AP_REQUEST: d1b08469-2ca8',
+        'sending [8]VERIFY: d1b08469-2ca8',
+        'sending [9]VERIFY: d1b08469-2ca8')
+test({'ACCEPT_QUERY_FAIL': '102'}, expected_trace=msgs)
+
+# Same messages as previous test.
+mark('First mech acceptor exchange fail')
+test({'ACCEPT_EXCHANGE_FAIL': '102'}, expected_trace=msgs)
+
+# Fail the optimistic mech's gss_exchange_meta_data() in the
+# initiator.  Since the acceptor has effectively selected the
+# optimistic mech, this causes the authentication to fail.
+mark('First mech initiator exchange fail, one hop')
+test({'HOPS': '1', 'INIT_EXCHANGE_FAIL': '102'}, expected_code=1,
+     expected_msg='No mutually supported NegoEx authentication schemes')
+mark('First mech initiator exchange fail, two hops, early keys')
+test({'HOPS': '2', 'INIT_EXCHANGE_FAIL': '102', 'KEY': 'always'},
+     expected_code=1,
+     expected_msg='No mutually supported NegoEx authentication schemes')
+mark('First mech initiator exchange fail, two hops')
+test({'HOPS': '2', 'INIT_EXCHANGE_FAIL': '102'}, expected_code=1,
+     expected_msg='No mutually supported NegoEx authentication schemes')
+
+mark('First mech init_sec_context fail')
+msgs = ('sending [0]INITIATOR_NEGO: d1b08469-2ca8-0000-0000-000000000000',
+        'sending [2]AP_REQUEST', 'sending [3]VERIFY', 'sending [6]VERIFY')
+test({'INIT_FAIL': '102'}, expected_trace=msgs)
+
+mark('First mech accept_sec_context fail')
+test({'HOPS': '2', 'ACCEPT_FAIL': '102'}, expected_code=1,
+     expected_msg='failure from acceptor')
+
+mark('ALERT from acceptor to initiator')
+msgs = ('sending [3]AP_REQUEST', 'sending [4]VERIFY', 'sending [8]CHALLENGE',
+        'sending [9]ALERT', 'received [9]ALERT', 'sending [10]AP_REQUEST',
+        'sending [11]VERIFY', 'sending [12]VERIFY')
+test({'HOPS': '3', 'KEY': 'init-always'}, expected_trace=msgs)
+
+mark('ALERT from initiator to acceptor')
+msgs = ('sending [3]AP_REQUEST', 'sending [7]CHALLENGE', 'sending [8]VERIFY',
+        'sending [9]AP_REQUEST', 'sending [10]ALERT', 'received [10]ALERT',
+        'sending [11]CHALLENGE', 'sending [12]VERIFY', 'sending [13]VERIFY')
+test({'HOPS': '4', 'KEY': 'accept-always'}, expected_trace=())
+
+success('NegoEx tests')