Csec_api - Provides authentication in LCG services
On the client side:
int Csec_client_initContext(Csec_context_t *ctx, int
service_type, Csec_protocol *protocols);
int Csec_client_establishContext(Csec_context_t *ctx, int
int Csec_client_setSecurityOpts(Csec_context_t *ctx, int
int Csec_client_setAuthorizationId(Csec_context_t *ctx, const
char *mech, const char *name);
int Csec_client_setVOMS_data(Csec_context_t *ctx, const char
*voname, char **fqan, int
On the server side:
int Csec_server_initContext(Csec_context_t *ctx, int
int Csec_server_reinitContext (Csec_context_t *ctx, int
int Csec_server_establishContext (Csec_context_t *ctx, int
int Csec_server_getClientId(Csec_context_t *ctx, char
**mech, char **name);
int Csec_server_getAuthorizationId(Csec_context_t *ctx, char
**mech, char **name);
int Csec_server_getDelegatedCredentials(Csec_context_t *ctx,
char **mech, void ** buf, size_t
int Csec_server_setSecurityOpts(Csec_context_t *ctx, int
char *Csec_server_get_client_ca(Csec_context_t *ctx);
char *Csec_server_get_client_vo(Csec_context_t *ctx);
char **Csec_server_get_client_fqans(Csec_context_t *ctx, int
int Csec_clearContext(Csec_context_t *ctx);
int Csec_getErrorMessageSummary(size_t maxlen);
int Csec_mapToLocalUser(const char *mech, const char
*name, char *username, size_t
username_size, uid_t *uid, gid_t
Csec_context_t * Csec_get_default_context();
functions allow for the implimentation of strong authentication
mechanisms in LCG servers and clients. Csec_api is integrated with the LCG
framework for errors.
- Csec_client_initContext, Csec_server_initContext,
- allow to initialize the Csec_context_t structure.
The service type parameter defines which type of key will be used by the
service. Its value can be:
- A normal host key (e.g. host/machine_name@DOMAIN for KRB5)
will be used
- A LCG Central host type key (e.g.
castorcentral/machine_name@DOMAIN for KRB5) will be used
- A LCG disk host type key (e.g.
castordisk/machine_name@DOMAIN for KRB5) will be used
- A LCG tape host type key (e.g.
castortape/machine_name@DOMAIN for KRB5) will be used
- Given an initialized context and an opened socket,
establish a security context according to the chosen security
- Given an initialized context, but one that has not yet been
used to establish a security context these functions allow the selection
of various options. Currently supported are:
Requests that delegated credentials from the client are made available to
the server. Either the client or server may set this option and it will
automaticaly limit the selection of authentication method to one that
supports delegation. (Currently only GSI)
This directs that client/server to disallow delegation. If the other side
requests delegation the establishing of a security context will fail.
If neither side sets any options the default behaviour is to not delegate a
- Allows a server to retrieve the authentication mechanism
and identification name (eg. principal or DN) from an established context,
ctx. If either of mech or name are NULL no pointer will be returned. The
strings that are returned are associated to the context, ctx, so should
only be used while the context ctx is valid. If required they should be
copied before the context is reset or cleared.
- On the client side an 'AuthorizationId' may be set against
an initialized but not yet established context. The AuthorizationId,
consisting of the pair mech and name, may be treated as any arbitrary pair
of strings up to CA_MAXCSECPROTOLEN, CA_MAXCSECNAMELEN in length. The
strings will be made available to the server. mech is supposed to
represent the mechanism type and name should be an identifying string such
as principal or DN.
On the server side, the AuthorizationId may be retrieved after the security
context is established. If the client did not set any id the server will
receive an error when Csec_server_getAuthorizationId() is called. Pointers
to the mechanism and the name will be returned in mech and name. Either
may be set to NULL, in which case no pointer is returned. Upon successful
return the list of VOMS fqans and the VOMS voname available to the server
will also be reset to those which the client set manually, or will be
emptied if the client did not set any. The strings returned are associated
with the context and should be copied before the context is reset or
- Allows a server to retrieve a copy of any delegated
credential available from an established context, ctx. The credential is
returned in buf. The size of the data in the buffer is returned in size.
The data should be treated as an opaque structure, the meaning of which
depends on the authentication scheme that was used. The scheme name is
returned in mech. Currently only mech 'GSI' supports credential delegation
and the client or server must request delegation passing by setting the
appropriate flag with Csec_client_setSecurityOpts() or
Csec_server_setSecurityOpts(). The GSI credential data is suitable for
passing to gss_import_cred(). mech and buf will point to data conatined
within the context, ctx, and should only be used while ctx remains
- This function determines whether an ID (mechanism, name
pair) can be mapped to a local uid/gid and/or username. If the username is
wanted a buffer should be passed in username, the size of which is
indicated with username_size. If the uid/gid are required uid and gid
should be passed. Any of username, uid or gid may be NULL in which case
they are not returned. If both uid and gid are NULL and username is
non-NULL the mapped username is not required to exist on the local system.
ie. the function will succeed as long as a mapping exists. If either of
uid or gid are non-NULL the mapping and local username must exist,
otherwise Csec_mapToLocalUser() will return an error.
- Clears the context and deallocates the memory used.
- Utility function that provides the applications with one
default per thread security context that can be used by the security
In case of errors in the Csec_pai layer, the functions return -1 (or NULL for
the functions returning strings), the serrno is set accordingly. It is
possible to get the detailed error message by using the
functions. The Csec_getErrorMessageSummary() function will return a summary
message that should need at most maxlen bytes of storage (including the
terminating null). The detail of the message may be cut in various ways to
reduce the length to fix in the specified length.
- environment variable or CSEC MECH entry in
This environment variable contains the list of protocols to be used for
authentication. The variable has precedence over the LCG configuration
On the client side, this list is used to choose which security mechanism
should be used to address the server. On the server side, this is is of
list of mechanisms that should be accepted by the server.
- If defined switches the tracing on in the LCG security
module. Tracing information is sent to stderr, unless CSEC_TRACEFILE is
- If defined, the LCG security tracing information is written
to afile which name is the value of this variable.
The currently supported methods for authentication are:
- Kerberos 5 mechanism
- Kerberos 4 mechanism
- Globus Security Infrastructure
- Unsecure protocol, should be used for testing only.
If the Csec_api library was compiled thread safe (eg. was built defining the
_THREAD_SAFE macro, which is the standard way) then the library should be
thread safe. If the application using Csec_api also defines _THREAD_SAFE, Csec
attempts to use thread safe versions of any underlying security libraries that
are used for the authentication service.
For instance, in the case of GSI the thread safe version of Globus may, in areas
other than security, sometimes create threads. If the application using
Csec_api needs to link to the GSI libraries for its own use then threading
flavour should be consistent. Therefore if the non threaded Globus libraries
are required then do not define the _THREAD_SAFE macro.
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