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kdc: honor PAC_ATTRIBUTES in presented TGT

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PACs are included when issuing TGTs, if there is no PAC_ATTRIBUTES buffer
(legacy behavior) or if the attributes buffer indicates the AS client requested
one.
This commit is contained in:
Luke Howard
2021-12-22 17:13:13 +11:00
parent b4f3617964
commit f18c9e06a8
5 changed files with 66 additions and 24 deletions
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70
kdc/krb5tgs.c
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@@ -90,6 +90,7 @@ _kdc_check_pac(krb5_context context,
krb5_boolean *kdc_issued,
krb5_pac *ppac,
krb5_principal *pac_canon_name,
krb5_boolean *pac_attributes_present,
uint64_t *pac_attributes)
{
krb5_pac pac = NULL;
@@ -100,6 +101,10 @@ _kdc_check_pac(krb5_context context,
*ppac = NULL;
if (pac_canon_name)
*pac_canon_name = NULL;
if (pac_attributes) {
*pac_attributes_present = FALSE;
*pac_attributes = 0;
}
ret = _krb5_kdc_pac_ticket_parse(context, tkt, &signedticket, &pac);
if (ret)
@@ -130,8 +135,10 @@ _kdc_check_pac(krb5_context context,
return ret;
}
}
if (pac_attributes)
_krb5_pac_get_attributes_info(context, pac, pac_attributes);
if (pac_attributes) {
*pac_attributes_present =
(_krb5_pac_get_attributes_info(context, pac, pac_attributes) == 0);
}
} else if (ret == KRB5_PLUGIN_NO_HANDLE) {
/*
* We can't verify the KDC signatures if the ticket was issued by
@@ -153,8 +160,10 @@ _kdc_check_pac(krb5_context context,
krb5_pac_free(context, pac);
return ret;
}
if (pac_attributes)
_krb5_pac_get_attributes_info(context, pac, pac_attributes);
if (pac_attributes) {
*pac_attributes_present =
(_krb5_pac_get_attributes_info(context, pac, pac_attributes) == 0);
}
}
/* Discard the PAC if the plugin didn't handle it */
@@ -805,6 +814,15 @@ tgs_make_reply(astgs_request_t r,
is_weak = 1;
}
if (r->client_princ) {
char *cpn;
krb5_unparse_name(r->context, r->client_princ, &cpn);
_kdc_audit_addkv((kdc_request_t)r, 0, "canon_client_name", "%s",
cpn ? cpn : "<unknown>");
krb5_xfree(cpn);
}
/*
* For anonymous tickets, we should filter out positive authorization data
* that could reveal the client's identity, and return a policy error for
@@ -815,25 +833,25 @@ tgs_make_reply(astgs_request_t r,
krb5_boolean is_tgs =
krb5_principal_is_krbtgt(r->context, server->entry.principal);
if (r->client_princ) {
char *cpn;
krb5_unparse_name(r->context, r->client_princ, &cpn);
_kdc_audit_addkv((kdc_request_t)r, 0, "canon_client_name", "%s",
cpn ? cpn : "<unknown>");
krb5_xfree(cpn);
}
if (r->pac_attributes_present)
_kdc_audit_addkv((kdc_request_t)r, 0, "pac_attributes", "%lx",
(long)r->pac_attributes);
/*
* The PAC should be the last change to the ticket. PAC attributes
* are not included for service tickets.
* PACs are included when issuing TGTs, if there is no PAC_ATTRIBUTES
* buffer (legacy behavior) or if the attributes buffer indicates the
* AS client requested one.
*/
ret = _krb5_kdc_pac_sign_ticket(r->context, mspac, tgt_name, serverkey,
krbtgtkey, rodc_id, NULL, r->client_princ,
add_ticket_sig, &et,
is_tgs ? &r->pac_attributes : NULL);
if (ret)
goto out;
if (is_tgs ||
!r->pac_attributes_present ||
(r->pac_attributes & (KRB5_PAC_WAS_REQUESTED | KRB5_PAC_WAS_GIVEN_IMPLICITLY))) {
ret = _krb5_kdc_pac_sign_ticket(r->context, mspac, tgt_name, serverkey,
krbtgtkey, rodc_id, NULL, r->client_princ,
add_ticket_sig, &et,
is_tgs ? &r->pac_attributes : NULL);
if (ret)
goto out;
}
}
/* It is somewhat unclear where the etype in the following
@@ -1471,6 +1489,7 @@ tgs_build_reply(astgs_request_t priv,
krb5_kvno kvno;
krb5_pac mspac = NULL;
krb5_pac user2user_pac = NULL;
krb5_boolean pac_attributes_present = FALSE;
uint16_t rodc_id;
krb5_boolean add_ticket_sig = FALSE;
const char *tgt_realm = /* Realm of TGT issuer */
@@ -1854,7 +1873,8 @@ server_lookup:
ret = _kdc_check_pac(context, config, user2user_princ, NULL,
user2user_client, user2user_krbtgt, user2user_krbtgt, user2user_krbtgt,
&uukey->key, &priv->ticket_key->key, &adtkt,
&user2user_kdc_issued, &user2user_pac, NULL, NULL);
&user2user_kdc_issued, &user2user_pac,
NULL, NULL, NULL);
_kdc_free_ent(context, user2user_client);
if (ret) {
const char *msg = krb5_get_error_message(context, ret);
@@ -1982,7 +2002,8 @@ server_lookup:
ret = _kdc_check_pac(context, config, cp, NULL, client, server, krbtgt, krbtgt,
&priv->ticket_key->key, &priv->ticket_key->key, tgt,
&kdc_issued, &mspac, &priv->client_princ, &priv->pac_attributes);
&kdc_issued, &mspac, &priv->client_princ,
&pac_attributes_present, &priv->pac_attributes);
if (ret) {
const char *msg = krb5_get_error_message(context, ret);
_kdc_audit_addreason((kdc_request_t)priv, "PAC check failed");
@@ -1992,6 +2013,7 @@ server_lookup:
krb5_free_error_message(context, msg);
goto out;
}
priv->pac_attributes_present = pac_attributes_present;
/*
* Process request
@@ -2314,7 +2336,8 @@ server_lookup:
*/
ret = _kdc_check_pac(context, config, tp, dp, adclient, server, krbtgt, client,
&clientkey->key, &priv->ticket_key->key, &adtkt,
&ad_kdc_issued, &mspac, &priv->client_princ, &priv->pac_attributes);
&ad_kdc_issued, &mspac, &priv->client_princ,
&pac_attributes_present, &priv->pac_attributes);
if (adclient)
_kdc_free_ent(context, adclient);
if (ret) {
@@ -2339,6 +2362,7 @@ server_lookup:
"Constrained delegation ticket not signed");
goto out;
}
priv->pac_attributes_present = pac_attributes_present;
kdc_log(context, config, 4, "constrained delegation for %s "
"from %s (%s) to %s", tpn, cpn, dpn, spn);