Tribblix: manual page: rpcsec

RPCSEC_GSS(3NSL) Networking Services Library Functions RPCSEC_GSS(3NSL)

NAME

rpcsec_gss - security flavor incorporating GSS-API protections

SYNOPSIS

cc [ flag... ] file... -lnsl [ library... ]
#include <rpc/rpcsec_gss.h>

DESCRIPTION

RPCSEC_GSS is a security flavor which sits "on top" of the GSS-API
(Generic Security Service API) for network transmissions.
Applications using RPCSEC_GSS can take advantage of GSS-API security
features; moreover, they can use any security mechanism (such as RSA
public key or Kerberos) that works with the GSS-API.

The GSS-API offers two security services beyond the traditional
authentication services (AUTH_DH, AUTH_SYS, and AUTH_KERB): integrity
and privacy. With integrity, the system uses cryptographic
checksumming to ensure the authenticity of a message (authenticity of
originator, recipient, and data); privacy provides additional
security by encrypting data. Applications using RPCSEC_GSS specify
which service they wish to use. Type of security service is
mechanism-independent.

Before exchanging data with a peer, an application must establish a
context for the exchange. RPCSEC_GSS provides a single function for
this purpose, rpc_gss_seccreate(), which allows the application to
specify the security mechanism, Quality of Protection (QOP), and type
of service at context creation. (The QOP parameter sets the
cryptographic algorithms to be used with integrity or privacy, and is
mechanism-dependent.) Once a context is established, applications can
reset the QOP and type of service for each data unit exchanged, if
desired.

Valid mechanisms and QOPs may be obtained from configuration files or
from the name service. Each mechanism has a default QOP.

Contexts are destroyed with the usual RPC auth_destroy() call.

Data Structures

Some of the data structures used by the RPCSEC_GSS package are shown
below.

rpc_gss_service_t
This enum defines the types of security services the context may
have. rpc_gss_seccreate() takes this as one argument when setting
the service type for a session.

typedef enum {
rpc_gss_svc_default = 0,
rpc_gss_svc_none = 1,
rpc_gss_svc_integrity = 2,
rpc_gss_svc_privacy = 3
} rpc_gss_service_t ;

rpc_gss_options_req_t
Structure containing options passed directly through to the GSS-API.
rpc_gss_seccreate() takes this as an argument when creating a
context.

typedef struct {
int req_flags; /*GSS request bits */
int time_req; /*requested credential lifetime */
gss_cred_id_t my_cred; /*GSS credential struct*/
gss_channel_bindings_t;
input_channel_bindings;
} rpc_gss_options_req_t ;

rpc_gss_OID
This data type is used by in-kernel RPC routines, and thus is
mentioned here for informational purposes only.

typedef struct {
u_int length;
void *elements
} *rpc_gss_OID;

rpc_gss_options_ret_t
Structure containing GSS-API options returned to the calling
function, rpc_gss_seccreate(). MAX_GSS_MECH is defined as 128.

typedef struct {
int major_status;
int minor_status;
u_int rpcsec_version /*vers. of RPCSEC_GSS */
int ret_flags
int time_req
gss_ctx_id_t gss_context;
char actual_mechanism[MAX_GSS_MECH]; /*mechanism used*/
} rpc_gss_options_ret_t;

rpc_gss_principal_t
The (mechanism-dependent, opaque) client principal type. Used as an
argument to the rpc_gss_get_principal_name() function, and in the
gsscred table. Also referenced by the rpc_gss_rawcred_t structure
for raw credentials (see below).

typedef struct {
int len;
char name[1];
} *rpc_gss_principal_t;

rpc_gss_rawcred_t
Structure for raw credentials. Used by rpc_gss_getcred() and
rpc_gss_set_callback().

typedef struct {
u_int version; /*RPC version # */
char *mechanism; /*security mechanism*/
char *qop; /*Quality of Protection*/
rpc_gss_principal_t client_principal; /*client name*/
char *svc_principal; /*server name*/
rpc_gss_service_t service; /*service (integrity, etc.)*/
} rpc_gss_rawcred_t;

rpc_gss_ucred_t
Structure for UNIX credentials. Used by rpc_gss_getcred() as an
alternative to rpc_gss_rawcred_t.

typedef struct {
uid_t uid; /*user ID*/
gid_t gid; /*group ID*/
short gidlen;
git_t *gidlist; /*list of groups*/
} rpc_gss_ucred_t;

rpc_gss_callback_t
Callback structure used by rpc_gss_set_callback().

typedef struct {
u_int program; /*RPC program #*/
u_int version; /*RPC version #*/
bool_t (*callback)(); /*user-defined callback routine*/
} rpc_gss_callback_t;

rpc_gss_lock_t
Structure used by a callback routine to enforce a particular QOP and
service for a session. The locked field is normally set to FALSE;
the server sets it to TRUE in order to lock the session. (A locked
context will reject all requests having different QOP and service
values than those found in the raw_cred structure.) For more
information, see the rpc_gss_set_callback(3NSL) man page.

typedef struct {
bool_t locked;
rpc_gss_rawcred_t *raw_cred;
} rpc_gss_lock_t;

rpc_gss_error_t
Structure used by rpc_gss_get_error() to fetch an error code when a
RPCSEC_GSS routine fails.

typedef struct {
int rpc_gss_error;
int system_error; /*same as errno*/
} rpc_gss_error_t;

Index to Routines

The following lists RPCSEC_GSS routines and the manual reference
pages on which they are described. An (S) indicates it is a server-
side function:

Routine (Manual Page)

Description

rpc_gss_seccreate(3NSL)

Create a secure RPCSEC_GSS context

rpc_gss_set_defaults(3NSL)

Switch service, QOP for a session

rpc_gss_max_data_length(3NSL)

Get maximum data length allowed by transport

rpc_gss_set_svc_name(3NSL)

Set server's principal name (S)

rpc_gss_getcred(3NSL)

Get credentials of caller (S)

rpc_gss_set_callback(3NSL)

Specify callback to see context use (S)

rpc_gss_get_principal_name(3NSL)

Get client principal name (S)

rpc_gss_svc_max_data_length(3NSL)

Get maximum data length allowed by transport (S)

rpc_gss_get_error(3NSL)

Get error number

rpc_gss_get_mechanisms(3NSL)

Get valid mechanism strings

rpc_gss_get_mech_info(3NSL)

Get valid QOP strings, current service

rpc_gss_get_versions(3NSL)

Get supported RPCSEC_GSS versions

rpc_gss_is_installed(3NSL)

Checks if a mechanism is installed

rpc_gss_mech_to_oid(3NSL)

Maps ASCII mechanism to OID representation

rpc_gss_qop_to_num(3NSL)

Maps ASCII QOP, mechansim to u_int number

Utilities

The gsscred utility manages the gsscred table, which contains
mappings of principal names between network and local credentials.
See gsscred(8).

FILES

/etc/gss/mech
List of installed mechanisms

/etc/gss/qop
List of valid QOPs

ATTRIBUTES