Files
heimdal/lib/hdb/hdb.h
Joseph Sutton ea8e8a4a8a kdc: Avoid races and multiple DB lookups in s4u2self check
Assists Samba to address CVE-2020-25719

Passing in target_server as a string principal means that for
an alias we must looking up the DB twice.

This is subject to a race and is a poor use of resources,
so instead just pass in the record we
already got when trying to confirm that the server in
S4U2Self is the same as the requesting client.

We also avoid doing a name comparison if the HDB plugin provides
a validation hook, this allows the HDB layer more freedom
to choose how to handle things.

In Samba AD the client record has already been bound to the the
original client by the SID check in the PAC, so the record is
known to match the ticket.

Likewise by looking up server only once we ensure that the
keys looked up originally (to decrypt) are in the record
we confirm the SID for here.

Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=14686

Signed-off-by: Andrew Bartlett <abartlet@samba.org>

(Based on Samba commit 05898cfb139ae0674c8251acc9d64c4c3d4c8376)
2021-12-16 16:09:07 +11:00

341 lines
12 KiB
C

/*
* Copyright (c) 1997 - 2007 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
*/
/* $Id$ */
#ifndef __HDB_H__
#define __HDB_H__
#include <stdio.h>
#include <krb5.h>
#include <hdb_err.h>
#include <heim_asn1.h>
#include <hdb_asn1.h>
typedef HDB_keyset hdb_keyset;
typedef HDB_entry hdb_entry;
typedef HDB_entry_alias hdb_entry_alias;
struct hdb_dbinfo;
enum hdb_lockop{ HDB_RLOCK, HDB_WLOCK };
/* flags for various functions */
#define HDB_F_DECRYPT 1 /* decrypt keys */
#define HDB_F_REPLACE 2 /* replace entry */
#define HDB_F_GET_CLIENT 4 /* fetch client */
#define HDB_F_GET_SERVER 8 /* fetch server */
#define HDB_F_GET_KRBTGT 16 /* fetch krbtgt */
#define HDB_F_GET_ANY 28 /* fetch any of client,server,krbtgt */
#define HDB_F_CANON 32 /* want canonicalition */
#define HDB_F_ADMIN_DATA 64 /* want data that kdc don't use */
#define HDB_F_KVNO_SPECIFIED 128 /* we want a particular KVNO */
#define HDB_F_CURRENT_KVNO 256 /* we want the current KVNO */
#define HDB_F_LIVE_CLNT_KVNOS 512 /* we want all live keys for pre-auth */
#define HDB_F_LIVE_SVC_KVNOS 1024 /* we want all live keys for tix */
#define HDB_F_ALL_KVNOS 2048 /* we want all the keys, live or not */
#define HDB_F_FOR_AS_REQ 4096 /* fetch is for a AS REQ */
#define HDB_F_FOR_TGS_REQ 8192 /* fetch is for a TGS REQ */
#define HDB_F_PRECHECK 16384 /* check that the operation would succeed */
#define HDB_F_DELAY_NEW_KEYS 32768 /* apply [hdb] new_service_key_delay */
#define HDB_F_SYNTHETIC_OK 65536 /* synthetic principal for PKINIT or GSS preauth OK */
#define HDB_F_GET_FAST_COOKIE 131072 /* fetch the FX-COOKIE key (not a normal principal) */
/* hdb_capability_flags */
#define HDB_CAP_F_HANDLE_ENTERPRISE_PRINCIPAL 1
#define HDB_CAP_F_HANDLE_PASSWORDS 2
#define HDB_CAP_F_PASSWORD_UPDATE_KEYS 4
#define HDB_CAP_F_SHARED_DIRECTORY 8
/* auth status values */
#define HDB_AUTH_SUCCESS 0
#define HDB_AUTH_WRONG_PASSWORD 1
#define HDB_AUTH_INVALID_SIGNATURE 2
/* key usage for master key */
#define HDB_KU_MKEY 0x484442
/*
* Second component of WELLKNOWN namespace principals, the third component is
* the common DNS suffix of the implied virtual hosts.
*/
#define HDB_WK_NAMESPACE "HOSTBASED-NAMESPACE"
typedef struct hdb_master_key_data *hdb_master_key;
/**
* hdb_entry_ex is a wrapper structure around the hdb_entry structure
* that allows backends to keep a pointer to the backing store, ie in
* ->hdb_fetch_kvno(), so that we the kadmin/kpasswd backend gets around to
* ->hdb_store(), the backend doesn't need to lookup the entry again.
*/
typedef struct hdb_entry_ex {
void *ctx;
hdb_entry entry;
void (*free_entry)(krb5_context, struct hdb_entry_ex *);
} hdb_entry_ex;
/**
* HDB backend function pointer structure
*
* The HDB structure is what the KDC and kadmind framework uses to
* query the backend database when talking about principals.
*/
typedef struct HDB {
void *hdb_db;
void *hdb_dbc; /** don't use, only for DB3 */
const char *hdb_method_name;
char *hdb_name;
int hdb_master_key_set;
hdb_master_key hdb_master_key;
int hdb_openp;
int hdb_capability_flags;
int lock_count;
int lock_type;
/*
* These fields cache config values.
*
* XXX Move these into a structure that we point to so that we
* don't need to break the ABI every time we add a field.
*/
int enable_virtual_hostbased_princs;
size_t virtual_hostbased_princ_ndots; /* Min. # of .s in hostname */
size_t virtual_hostbased_princ_maxdots; /* Max. # of .s in namespace */
char **virtual_hostbased_princ_svcs; /* Which svcs are not wildcarded */
time_t new_service_key_delay; /* Delay for new keys */
/**
* Open (or create) the a Kerberos database.
*
* Open (or create) the a Kerberos database that was resolved with
* hdb_create(). The third and fourth flag to the function are the
* same as open(), thus passing O_CREAT will create the data base
* if it doesn't exists.
*
* Then done the caller should call hdb_close(), and to release
* all resources hdb_destroy().
*/
krb5_error_code (*hdb_open)(krb5_context, struct HDB*, int, mode_t);
/**
* Close the database for transaction
*
* Closes the database for further transactions, wont release any
* permanant resources. the database can be ->hdb_open-ed again.
*/
krb5_error_code (*hdb_close)(krb5_context, struct HDB*);
/**
* Free an entry after use.
*/
void (*hdb_free)(krb5_context, struct HDB*, hdb_entry_ex*);
/**
* Fetch an entry from the backend
*
* Fetch an entry from the backend, flags are what type of entry
* should be fetch: client, server, krbtgt.
* knvo (if specified and flags HDB_F_KVNO_SPECIFIED set) is the kvno to get
*/
krb5_error_code (*hdb_fetch_kvno)(krb5_context, struct HDB*,
krb5_const_principal, unsigned, krb5_kvno,
hdb_entry_ex*);
/**
* Store an entry to database
*/
krb5_error_code (*hdb_store)(krb5_context, struct HDB*,
unsigned, hdb_entry_ex*);
/**
* Remove an entry from the database.
*/
krb5_error_code (*hdb_remove)(krb5_context, struct HDB*,
unsigned, krb5_const_principal);
/**
* As part of iteration, fetch one entry
*/
krb5_error_code (*hdb_firstkey)(krb5_context, struct HDB*,
unsigned, hdb_entry_ex*);
/**
* As part of iteration, fetch next entry
*/
krb5_error_code (*hdb_nextkey)(krb5_context, struct HDB*,
unsigned, hdb_entry_ex*);
/**
* Lock database
*
* A lock can only be held by one consumers. Transaction can still
* happen on the database while the lock is held, so the entry is
* only useful for syncroning creation of the database and renaming of the database.
*/
krb5_error_code (*hdb_lock)(krb5_context, struct HDB*, int);
/**
* Unlock database
*/
krb5_error_code (*hdb_unlock)(krb5_context, struct HDB*);
/**
* Rename the data base.
*
* Assume that the database is not hdb_open'ed and not locked.
*/
krb5_error_code (*hdb_rename)(krb5_context, struct HDB*, const char*);
/**
* Get an hdb_entry from a classical DB backend
*
* This function takes a principal key (krb5_data) and returns all
* data related to principal in the return krb5_data. The returned
* encoded entry is of type hdb_entry or hdb_entry_alias.
*/
krb5_error_code (*hdb__get)(krb5_context, struct HDB*,
krb5_data, krb5_data*);
/**
* Store an hdb_entry from a classical DB backend
*
* This function takes a principal key (krb5_data) and encoded
* hdb_entry or hdb_entry_alias as the data to store.
*
* For a file-based DB, this must synchronize to disk when done.
* This is sub-optimal for kadm5_s_rename_principal(), and for
* kadm5_s_modify_principal() when using principal aliases; to
* improve this so that only one fsync() need be done
* per-transaction will require HDB API extensions.
*/
krb5_error_code (*hdb__put)(krb5_context, struct HDB*, int,
krb5_data, krb5_data);
/**
* Delete and hdb_entry from a classical DB backend
*
* This function takes a principal key (krb5_data) naming the record
* to delete.
*
* Same discussion as in @ref HDB::hdb__put
*/
krb5_error_code (*hdb__del)(krb5_context, struct HDB*, krb5_data);
/**
* Destroy the handle to the database.
*
* Destroy the handle to the database, deallocate all memory and
* related resources. Does not remove any permanent data. Its the
* logical reverse of hdb_create() function that is the entry
* point for the module.
*/
krb5_error_code (*hdb_destroy)(krb5_context, struct HDB*);
/**
* Get the list of realms this backend handles.
* This call is optional to support. The returned realms are used
* for announcing the realms over bonjour. Free returned array
* with krb5_free_host_realm().
*/
krb5_error_code (*hdb_get_realms)(krb5_context, struct HDB *, krb5_realm **);
/**
* Change password.
*
* Will update keys for the entry when given password. The new
* keys must be written into the entry and will then later be
* ->hdb_store() into the database. The backend will still perform
* all other operations, increasing the kvno, and update
* modification timestamp.
*
* The backend needs to call _kadm5_set_keys() and perform password
* quality checks.
*/
krb5_error_code (*hdb_password)(krb5_context, struct HDB*, hdb_entry_ex*, const char *, int);
/**
* Auth feedback
*
* This is a feedback call that allows backends that provides
* lockout functionality to register failure and/or successes.
*
* In case the entry is locked out, the backend should set the
* hdb_entry.flags.locked-out flag.
*/
krb5_error_code (*hdb_auth_status)(krb5_context, struct HDB *, hdb_entry_ex *, int);
/**
* Check if delegation is allowed.
*/
krb5_error_code (*hdb_check_constrained_delegation)(krb5_context, struct HDB *, hdb_entry_ex *, krb5_const_principal);
/**
* Check if this name is an alias for the supplied client for PKINIT userPrinicpalName logins
*/
krb5_error_code (*hdb_check_pkinit_ms_upn_match)(krb5_context, struct HDB *, hdb_entry_ex *, krb5_const_principal);
/**
* Check if s4u2self is allowed from this client to this server
*/
krb5_error_code (*hdb_check_s4u2self)(krb5_context, struct HDB *, hdb_entry_ex *, hdb_entry_ex *);
/**
* Enable/disable synchronous updates
*
* Calling this with 0 disables sync. Calling it with non-zero enables
* sync and does an fsync().
*/
krb5_error_code (*hdb_set_sync)(krb5_context, struct HDB *, int);
}HDB;
#define HDB_INTERFACE_VERSION 11
struct hdb_method {
int version;
unsigned int is_file_based:1;
unsigned int can_taste:1;
krb5_error_code (*init)(krb5_context, void **);
void (*fini)(void *);
const char *prefix;
krb5_error_code (*create)(krb5_context, HDB **, const char *filename);
};
/* dump entry format, for hdb_print_entry() */
typedef enum hdb_dump_format {
HDB_DUMP_HEIMDAL = 0,
HDB_DUMP_MIT = 1,
} hdb_dump_format_t;
struct hdb_print_entry_arg {
FILE *out;
hdb_dump_format_t fmt;
};
typedef krb5_error_code (*hdb_foreach_func_t)(krb5_context, HDB*,
hdb_entry_ex*, void*);
extern krb5_kt_ops hdb_kt_ops;
extern krb5_kt_ops hdb_get_kt_ops;
extern const int hdb_interface_version;
#include <hdb-protos.h>
#endif /* __HDB_H__ */