Subject: krb5 Key Distribution Center (KDC) daemon DoS
Origin: upstream, http://web.mit.edu/Kerberos/advisories/MITKRB5-SA-2011-002.txt
The MIT krb5 Key Distribution Center (KDC) daemon is vulnerable to
denial of service attacks from unauthenticated remote attackers.
CVE-2011-0281 and CVE-2011-0282 occur only in KDCs using LDAP back
ends, but CVE-2011-0283 occurs in all krb5-1.9 KDCs.
Exploit code is not known to exist, but the vulnerabilities are easy
to trigger manually. The trigger for CVE-2011-0281 has already been
disclosed publicly, but that fact might not be obvious to casual
readers of the message in which it was disclosed. The triggers for
CVE-2011-0282 and CVE-2011-0283 have not yet been disclosed publicly,
but they are also trivial.
diff --git a/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap.h b/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap.h
index 1ca09b4..60caf3d 100644
--- a/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap.h
+++ b/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap.h
@@ -102,14 +102,18 @@ extern void prepend_err_str (krb5_context ctx, const char *s, krb5_error_code er
#define LDAP_SEARCH(base, scope, filter, attrs) LDAP_SEARCH_1(base, scope, filter, attrs, CHECK_STATUS)
#define LDAP_SEARCH_1(base, scope, filter, attrs, status_check) \
- do { \
- st = ldap_search_ext_s(ld, base, scope, filter, attrs, 0, NULL, NULL, &timelimit, LDAP_NO_LIMIT, &result); \
- if (translate_ldap_error(st, OP_SEARCH) == KRB5_KDB_ACCESS_ERROR) { \
- tempst = krb5_ldap_rebind(ldap_context, &ldap_server_handle); \
- if (ldap_server_handle) \
- ld = ldap_server_handle->ldap_handle; \
- } \
- }while (translate_ldap_error(st, OP_SEARCH) == KRB5_KDB_ACCESS_ERROR && tempst == 0); \
+ tempst = 0; \
+ st = ldap_search_ext_s(ld, base, scope, filter, attrs, 0, NULL, \
+ NULL, &timelimit, LDAP_NO_LIMIT, &result); \
+ if (translate_ldap_error(st, OP_SEARCH) == KRB5_KDB_ACCESS_ERROR) { \
+ tempst = krb5_ldap_rebind(ldap_context, &ldap_server_handle); \
+ if (ldap_server_handle) \
+ ld = ldap_server_handle->ldap_handle; \
+ if (tempst == 0) \
+ st = ldap_search_ext_s(ld, base, scope, filter, attrs, 0, \
+ NULL, NULL, &timelimit, \
+ LDAP_NO_LIMIT, &result); \
+ } \
\
if (status_check != IGNORE_STATUS) { \
if (tempst != 0) { \
diff --git a/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap_conn.c b/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap_conn.c
index 82b0333..84e80ee 100644
--- a/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap_conn.c
+++ b/src/plugins/kdb/ldap/libkdb_ldap/kdb_ldap_conn.c
@@ -302,6 +302,7 @@ krb5_ldap_rebind(krb5_ldap_context *ldap_context,
{
krb5_ldap_server_handle *handle = *ldap_server_handle;
+ ldap_unbind_ext_s(handle->ldap_handle, NULL, NULL);
if ((ldap_initialize(&handle->ldap_handle, handle->server_info->server_name) != LDAP_SUCCESS)
|| (krb5_ldap_bind(ldap_context, handle) != LDAP_SUCCESS))
return krb5_ldap_request_next_handle_from_pool(ldap_context, ldap_server_handle);
diff --git a/src/plugins/kdb/ldap/libkdb_ldap/ldap_misc.c b/src/plugins/kdb/ldap/libkdb_ldap/ldap_misc.c
index f549e23..b70940f 100644
--- a/src/plugins/kdb/ldap/libkdb_ldap/ldap_misc.c
+++ b/src/plugins/kdb/ldap/libkdb_ldap/ldap_misc.c
@@ -446,12 +446,11 @@ is_principal_in_realm(krb5_ldap_context *ldap_context,
* portion, then the first portion of the principal name SHOULD be
* "krbtgt". All this check is done in the immediate block.
*/
- if (searchfor->length == 2)
- if ((strncasecmp(searchfor->data[0].data, "krbtgt",
- FIND_MAX(searchfor->data[0].length, strlen("krbtgt"))) == 0) &&
- (strncasecmp(searchfor->data[1].data, defrealm,
- FIND_MAX(searchfor->data[1].length, defrealmlen)) == 0))
+ if (searchfor->length == 2) {
+ if (data_eq_string(searchfor->data[0], "krbtgt") &&
+ data_eq_string(searchfor->data[1], defrealm))
return 0;
+ }
/* first check the length, if they are not equal, then they are not same */
if (strlen(defrealm) != searchfor->realm.length)
diff --git a/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c b/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
index 7ad31da..626ed1f 100644
--- a/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
+++ b/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
@@ -103,10 +103,10 @@ krb5_ldap_get_principal(krb5_context context, krb5_const_principal searchfor,
unsigned int flags, krb5_db_entry *entries,
int *nentries, krb5_boolean *more)
{
- char *user=NULL, *filter=NULL, **subtree=NULL;
+ char *user=NULL, *filter=NULL, *filtuser=NULL;
unsigned int tree=0, ntrees=1, princlen=0;
krb5_error_code tempst=0, st=0;
- char **values=NULL, *cname=NULL;
+ char **values=NULL, **subtree=NULL, *cname=NULL;
LDAP *ld=NULL;
LDAPMessage *result=NULL, *ent=NULL;
krb5_ldap_context *ldap_context=NULL;
@@ -142,12 +142,18 @@ krb5_ldap_get_principal(krb5_context context, krb5_const_principal searchfor,
if ((st=krb5_ldap_unparse_principal_name(user)) != 0)
goto cleanup;
- princlen = strlen(FILTER) + strlen(user) + 2 + 1; /* 2 for closing brackets */
+ filtuser = ldap_filter_correct(user);
+ if (filtuser == NULL) {
+ st = ENOMEM;
+ goto cleanup;
+ }
+
+ princlen = strlen(FILTER) + strlen(filtuser) + 2 + 1; /* 2 for closing brackets */
if ((filter = malloc(princlen)) == NULL) {
st = ENOMEM;
goto cleanup;
}
- snprintf(filter, princlen, FILTER"%s))", user);
+ snprintf(filter, princlen, FILTER"%s))", filtuser);
if ((st = krb5_get_subtree_info(ldap_context, &subtree, &ntrees)) != 0)
goto cleanup;
@@ -231,6 +237,9 @@ cleanup:
if (user)
free(user);
+ if (filtuser)
+ free(filtuser);
+
if (cname)
free(cname);
