a684e001ba
Our initiator supports configuration-driven delegation of destination
TGTs.
This commit adds acceptor-side handling of destination TGT policy to
reject storing of non-destination TGTs when destination TGTs are
desired.
Currently we use the same appdefault for this.
Background:
A root TGT is one of the form krbtgt/REALM@SAME-REALM.
A destination TGT is a root TGT for the same realm as the acceptor
service's realm.
Normally clients delegate a root TGT for the client's realm.
In some deployments clients may want to delegate destination TGTs as
a form of constrained delegation: so that the destination service
cannot use the delegated credential to impersonate the client
principal to services in its home realm (due to KDC lineage/transit
checks). In those deployments there may not even be a route back to
the KDCs of the client's realm, and attempting to use a
non-destination TGT might even lead to timeouts.
372 lines
13 KiB
C
372 lines
13 KiB
C
/*
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* Copyright (c) 2003 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "gsskrb5_locl.h"
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static int
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same_princ(krb5_context context, krb5_ccache id1, krb5_ccache id2)
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{
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krb5_error_code ret;
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krb5_principal p1 = NULL;
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krb5_principal p2 = NULL;
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int same = 0;
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ret = krb5_cc_get_principal(context, id1, &p1);
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if (ret == 0)
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ret = krb5_cc_get_principal(context, id2, &p2);
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/* If either principal is absent, it's the same for our purposes */
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same = ret ? 1 : krb5_principal_compare(context, p1, p2);
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krb5_free_principal(context, p1);
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krb5_free_principal(context, p2);
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return same;
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}
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static OM_uint32
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add_env(OM_uint32 *minor,
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gss_buffer_set_t *env,
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const char *var,
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const char *val)
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{
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OM_uint32 major;
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gss_buffer_desc b;
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char *varval = NULL;
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if (asprintf(&varval, "%s=%s", var, val) == -1 || varval == NULL) {
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*minor = ENOMEM;
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return GSS_S_FAILURE;
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}
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b.value = varval;
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b.length = strlen(varval) + 1;
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major = gss_add_buffer_set_member(minor, &b, env);
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free(varval);
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return major;
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}
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static OM_uint32
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set_proc(OM_uint32 *minor, gss_buffer_set_t env)
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{
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/*
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* XXX On systems with setpag(), call setpag(). On WIN32... create a
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* session, set the access token, ...?
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*/
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#ifndef WIN32
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size_t i;
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for (i = 0; i < env->count; i++)
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putenv(env->elements[i].value);
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#endif
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return GSS_S_COMPLETE;
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}
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/*
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* A principal is the best principal for a user IFF
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*
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* - it has one component
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* - the one component is the same as the user's name
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* - the real is the user_realm from configuration
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*/
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static int
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principal_is_best_for_user(krb5_context context,
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const char *app,
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krb5_const_principal p,
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const char *user)
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{
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char *default_realm = NULL;
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char *user_realm = NULL;
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int ret;
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(void) krb5_get_default_realm(context, &default_realm);
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krb5_appdefault_string(context, app, NULL, "user_realm", default_realm,
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&user_realm);
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ret = user_realm &&
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krb5_principal_get_num_comp(context, p) == 1 &&
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strcmp(user_realm, krb5_principal_get_realm(context, p)) == 0 &&
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(!user ||
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strcmp(user, krb5_principal_get_comp_string(context, p, 0)) == 0);
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free(default_realm);
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free(user_realm);
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return ret;
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}
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static krb5_error_code
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check_destination_tgt_policy(krb5_context context,
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const char *appname,
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gsskrb5_cred input_cred)
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{
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krb5_error_code ret;
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krb5_boolean want_dst_tgt = 0;
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krb5_data v;
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if (input_cred->destination_realm == NULL)
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/*
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* Not a delegated credential, so we can't check the destination TGT
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* policy for the realm of the service -- we don't know the realm of
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* the service.
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*/
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return 0;
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krb5_appdefault_boolean(context, appname, input_cred->destination_realm,
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"require_delegate_destination_tgt", FALSE,
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&want_dst_tgt);
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if (!want_dst_tgt)
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return 0;
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krb5_data_zero(&v);
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ret = krb5_cc_get_config(context, input_cred->ccache, NULL,
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"start_realm", &v);
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if (ret == 0 &&
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v.length != strlen(input_cred->destination_realm))
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ret = KRB5_CC_NOTFOUND;
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if (ret == 0 &&
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strncmp(input_cred->destination_realm, v.data, v.length) != 0)
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ret = KRB5_CC_NOTFOUND;
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if (ret)
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krb5_set_error_message(context, ret,
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"Delegated TGT is not a destination TGT for "
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"realm \"%s\" but for \"%.*s\"",
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input_cred->destination_realm,
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(int)(v.length ? v.length : sizeof("<UNKNOWN>") - 1),
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v.data ? (const char *)v.data : "<UNKNOWN>");
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krb5_data_free(&v);
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return ret;
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}
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OM_uint32 GSSAPI_CALLCONV
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_gsskrb5_store_cred_into2(OM_uint32 *minor_status,
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gss_const_cred_id_t input_cred_handle,
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gss_cred_usage_t cred_usage,
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const gss_OID desired_mech,
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OM_uint32 store_cred_flags,
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gss_const_key_value_set_t cred_store,
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gss_OID_set *elements_stored,
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gss_cred_usage_t *cred_usage_stored,
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gss_buffer_set_t *envp)
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{
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krb5_context context;
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krb5_error_code ret;
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gsskrb5_cred input_cred;
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krb5_ccache id = NULL;
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time_t exp_current;
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time_t exp_new;
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gss_buffer_set_t env = GSS_C_NO_BUFFER_SET;
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const char *cs_unique_ccache = NULL;
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const char *cs_ccache_name = NULL;
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const char *cs_user_name = NULL;
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const char *cs_app_name = NULL;
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char *ccache_name = NULL;
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OM_uint32 major_status, junk;
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OM_uint32 overwrite_cred = store_cred_flags & GSS_C_STORE_CRED_OVERWRITE;
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int default_for = 0;
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*minor_status = 0;
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/* Sanity check inputs */
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if (cred_usage != GSS_C_INITIATE) {
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/* It'd be nice if we could also do accept, writing a keytab */
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*minor_status = GSS_KRB5_S_G_BAD_USAGE;
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return GSS_S_FAILURE;
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}
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if (desired_mech != GSS_C_NO_OID &&
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gss_oid_equal(desired_mech, GSS_KRB5_MECHANISM) == 0)
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return GSS_S_BAD_MECH;
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if (input_cred_handle == GSS_C_NO_CREDENTIAL)
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return GSS_S_CALL_INACCESSIBLE_READ;
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input_cred = (gsskrb5_cred)input_cred_handle;
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/* Sanity check the input_cred */
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if (input_cred->usage != cred_usage && input_cred->usage != GSS_C_BOTH) {
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*minor_status = GSS_KRB5_S_G_BAD_USAGE;
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return GSS_S_NO_CRED;
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}
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if (input_cred->principal == NULL) {
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*minor_status = GSS_KRB5_S_KG_TGT_MISSING;
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return GSS_S_NO_CRED;
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}
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/* Extract the ccache name from the store if given */
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if (cred_store != GSS_C_NO_CRED_STORE) {
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major_status = __gsskrb5_cred_store_find(minor_status, cred_store,
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"unique_ccache_type",
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&cs_unique_ccache);
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if (GSS_ERROR(major_status))
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return major_status;
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major_status = __gsskrb5_cred_store_find(minor_status, cred_store,
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"ccache", &cs_ccache_name);
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if (GSS_ERROR(major_status))
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return major_status;
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major_status = __gsskrb5_cred_store_find(minor_status, cred_store,
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"username", &cs_user_name);
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if (GSS_ERROR(major_status))
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return major_status;
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major_status = __gsskrb5_cred_store_find(minor_status, cred_store,
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"appname", &cs_app_name);
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if (GSS_ERROR(major_status))
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return major_status;
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}
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GSSAPI_KRB5_INIT (&context);
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HEIMDAL_MUTEX_lock(&input_cred->cred_id_mutex);
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if (cs_ccache_name && strchr(cs_ccache_name, '%')) {
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ret = _krb5_expand_default_cc_name(context, cs_ccache_name,
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&ccache_name);
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if (ret) {
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HEIMDAL_MUTEX_unlock(&input_cred->cred_id_mutex);
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*minor_status = ret;
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return GSS_S_FAILURE;
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}
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cs_ccache_name = ccache_name;
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}
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/* More sanity checking of the input_cred (good to fail early) */
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ret = krb5_cc_get_lifetime(context, input_cred->ccache, &exp_new);
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if (ret) {
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HEIMDAL_MUTEX_unlock(&input_cred->cred_id_mutex);
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*minor_status = ret;
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free(ccache_name);
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return GSS_S_NO_CRED;
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}
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ret = check_destination_tgt_policy(context, cs_app_name, input_cred);
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if (ret) {
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HEIMDAL_MUTEX_unlock(&input_cred->cred_id_mutex);
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*minor_status = ret;
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free(ccache_name);
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return GSS_S_NO_CRED;
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}
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/*
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* Find an appropriate ccache, which will be one of:
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*
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* - the one given in the cred_store, if given
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* - a new unique one for some ccache type in the cred_store, if given
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* - a subsidiary cache named for the principal in the default collection,
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* if the principal is the "best principal for the user"
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* - the default ccache
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*/
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if (cs_ccache_name) {
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ret = krb5_cc_resolve(context, cs_ccache_name, &id);
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} else if (cs_unique_ccache) {
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overwrite_cred = 1;
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ret = krb5_cc_new_unique(context, cs_unique_ccache, NULL, &id);
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} else if (principal_is_best_for_user(context, cs_app_name,
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input_cred->principal,
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cs_user_name)) {
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ret = krb5_cc_default(context, &id);
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if (ret == 0 && !same_princ(context, id, input_cred->ccache)) {
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krb5_cc_close(context, id);
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ret = krb5_cc_default_for(context, input_cred->principal, &id);
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default_for = 1;
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}
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} else {
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ret = krb5_cc_default_for(context, input_cred->principal, &id);
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default_for = 1;
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}
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if (ret || id == NULL) {
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HEIMDAL_MUTEX_unlock(&input_cred->cred_id_mutex);
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*minor_status = ret;
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free(ccache_name);
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return ret == 0 ? GSS_S_NO_CRED : GSS_S_FAILURE;
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}
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/*
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* If we're using a subsidiary ccache for this principal and it has some
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* other principal's tickets in it -> overwrite.
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*/
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if (!overwrite_cred && default_for &&
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!same_princ(context, id, input_cred->ccache))
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overwrite_cred = 1;
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if (!overwrite_cred && same_princ(context, id, input_cred->ccache)) {
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/*
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* If current creds are for the same princ as we already had creds for,
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* and the new creds live longer than the old, overwrite.
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*/
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ret = krb5_cc_get_lifetime(context, id, &exp_current);
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if (ret != 0 || exp_new > exp_current)
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overwrite_cred = 1;
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}
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if (overwrite_cred) {
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ret = krb5_cc_initialize(context, id, input_cred->principal);
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if (ret == 0)
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ret = krb5_cc_copy_match_f(context, input_cred->ccache, id, NULL, NULL,
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NULL);
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}
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if ((store_cred_flags & GSS_C_STORE_CRED_SET_PROCESS) && envp == NULL)
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envp = &env;
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if (envp != NULL) {
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char *fullname = NULL;
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if ((ret = krb5_cc_get_full_name(context, id, &fullname)) == 0) {
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major_status = add_env(minor_status, envp, "KRB5CCNAME", fullname);
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free(fullname);
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if (major_status)
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ret = *minor_status;
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}
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}
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(void) krb5_cc_close(context, id);
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HEIMDAL_MUTEX_unlock(&input_cred->cred_id_mutex);
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if (ret == 0 && (store_cred_flags & GSS_C_STORE_CRED_SET_PROCESS) &&
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(major_status = set_proc(minor_status, *envp)) != GSS_S_COMPLETE)
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ret = *minor_status;
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(void) gss_release_buffer_set(&junk, &env);
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free(ccache_name);
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*minor_status = ret;
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return ret ? GSS_S_FAILURE : GSS_S_COMPLETE;
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}
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OM_uint32 GSSAPI_CALLCONV
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_gsskrb5_store_cred_into(OM_uint32 *minor_status,
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gss_const_cred_id_t input_cred_handle,
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gss_cred_usage_t cred_usage,
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const gss_OID desired_mech,
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OM_uint32 overwrite_cred,
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OM_uint32 default_cred,
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gss_const_key_value_set_t cred_store,
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gss_OID_set *elements_stored,
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gss_cred_usage_t *cred_usage_stored)
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{
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OM_uint32 store_cred_flags =
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(overwrite_cred ? GSS_C_STORE_CRED_OVERWRITE : 0) |
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(default_cred ? GSS_C_STORE_CRED_DEFAULT : 0);
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return _gsskrb5_store_cred_into2(minor_status, input_cred_handle,
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cred_usage, desired_mech,
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store_cred_flags, cred_store,
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elements_stored, cred_usage_stored, NULL);
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}
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