Projects/GS2
Background
Some additional features in the GSS mechanism glue are useful for implementors of SASL GS2.
- RFC 5801: GSS_Inquire_SASLname_for_mech and GSS_Inquire_mech_for_SASLname
- RFC 5587: gss_inquire_attrs_for_mech &c
These allow a SASL library to dynamically bridge GSS mechanisms without mechanism-specific knowledge.
Architecture
The functionality of the aforementioned APIs is as follows:
- a bidirectional mapping between GSS OIDs and SASL mechanism names. (In the case of no mapping, the mechanism glue synthesises a SASL name using a base-32 encoded SHA-1 of the OID.)
- a means to determine which features, denoted by OIDs, are supported by mechanisms
For example, a GS2 implementation that wished to ignore negotiate mechanisms whilst selecting mechanisms that supported mutual authentication, might do:
static int gs2_indicate_mechs(void) { OM_uint32 major, minor; gss_OID_desc desired_oids[2]; gss_OID_set_desc desired_attrs; gss_OID_desc except_oids[3]; gss_OID_set_desc except_attrs; desired_oids[0] = *GSS_C_MA_AUTH_INIT; desired_oids[1] = *GSS_C_MA_AUTH_TARG; desired_attrs.count = sizeof(desired_oids)/sizeof(desired_oids[0]); desired_attrs.elements = desired_oids; except_oids[0] = *GSS_C_MA_MECH_NEGO; except_oids[1] = *GSS_C_MA_NOT_MECH; except_oids[2] = *GSS_C_MA_DEPRECATED; except_attrs.count = sizeof(except_oids)/sizeof(except_oids[0]); except_attrs.elements = except_oids; major = gss_indicate_mechs_by_attrs(&minor, &desired_attrs, &except_attrs, GSS_C_NO_OID_SET, &gs2_mechs); if (GSS_ERROR(major)) { return SASL_FAIL; } return SASL_OK;
Implementation
The implementations live in src/lib/gssapi/mechglue/g_saslname.c and src/lib/gssapi/mechglue/g_mechattr.c, respectively.
OM_uint32 KRB5_CALLCONV gss_inquire_saslname_for_mech( OM_uint32 *minor_status, const gss_OID desired_mech, gss_buffer_t sasl_mech_name, gss_buffer_t mech_name, gss_buffer_t mech_description); OM_uint32 KRB5_CALLCONV gss_inquire_mech_for_saslname( OM_uint32 *minor_status, const gss_buffer_t sasl_mech_name, gss_OID *mech_type); OM_uint32 KRB5_CALLCONV gss_indicate_mechs_by_attrs( OM_uint32 *, /* minor_status */ gss_const_OID_set, /* desired_mech_attrs */ gss_const_OID_set, /* except_mech_attrs */ gss_const_OID_set, /* critical_mech_attrs */ gss_OID_set *); /* mechs */ OM_uint32 KRB5_CALLCONV gss_inquire_attrs_for_mech( OM_uint32 *, /* minor_status */ gss_const_OID, /* mech */ gss_OID_set *, /* mech_attrs */ gss_OID_set *); /* known_mech_attrs */ OM_uint32 KRB5_CALLCONV gss_display_mech_attr( OM_uint32 *, /* minor_status */ gss_const_OID, /* mech_attr */ gss_buffer_t, /* name */ gss_buffer_t, /* short_desc */ gss_buffer_t); /* long_desc */
If a mechanism does not provide the entry point or returns GSS_S_BAD_MECH, then the name is mapped as described above.
The Kerberos and SPNEGO mechanisms have been updated to return GS2-KRB5 and SPNEGO, respectively, as their SASL names.
Status
Implemented and tested with a prototype GS2 implementation, as well as a mechanism plugin. Code is in the users/lhoward/sasl-gs2 branch (note that this is branched off import-cred; pick up only the changes you need).
A test program is in src/tests/gssapi/t_saslname.c.
GS2 implementation at http://www.project-moonshot.org/git/cyrus-sasl in plugins/gs2.c.
Examples
A list of GS2 mechanisms and their attributes.
------------------------------------------------------------------------------ OID : { 1 2 840 113554 1 2 2 } SASL mech : GS2-KRB5 Mech name : krb5 Mech desc : Kerberos 5 GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ OID : { 1 3 5 1 5 2 } SASL mech : GS2-KRB5 Mech name : krb5 Mech desc : Kerberos 5 GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ Got different OID { 1 2 840 113554 1 2 2 } for mechanism GS2-KRB5 ------------------------------------------------------------------------------ OID : { 1 2 840 48018 1 2 2 } SASL mech : GS2-KRB5 Mech name : krb5 Mech desc : Kerberos 5 GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ OID : { 1 3 6 1 5 2 5 } SASL mech : GS2-KRB5 Mech name : krb5 Mech desc : Kerberos 5 GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ Got different OID { 1 2 840 113554 1 2 2 } for mechanism GS2-KRB5 ------------------------------------------------------------------------------ OID : { 1 3 6 1 5 5 2 } SASL mech : SPNEGO Mech name : spnego Mech desc : Simple and Protected GSS-API Negotiation Mechanism Mech attrs: GSS_C_MA_MECH_NEGO GSS_C_MA_ITOK_FRAMED GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ OID : { 1 3 6 1 4 1 5322 21 1 16 } SASL mech : GS2-ZGMBGB5SLBQ Mech name : eap-des3-cbc-sha1 Mech desc : Extensible Authentication Protocol GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ OID : { 1 3 6 1 4 1 5322 21 1 17 } SASL mech : GS2-EAP-AES128 Mech name : eap-aes128-cts-hmac-sha1-96 Mech desc : Extensible Authentication Protocol GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ OID : { 1 3 6 1 4 1 5322 21 1 18 } SASL mech : GS2-EAP-AES256 Mech name : eap-aes256-cts-hmac-sha1-96 Mech desc : Extensible Authentication Protocol GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ OID : { 1 3 6 1 4 1 5322 21 1 23 } SASL mech : GS2-6PUERUGDUSC Mech name : eap-arcfour-hmac Mech desc : Extensible Authentication Protocol GSS-API Mechanism Mech attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_CTX_TRANS GSS_C_MA_NOT_DFLT_MECH Known attrs: GSS_C_MA_MECH_CONCRETE GSS_C_MA_MECH_PSEUDO GSS_C_MA_MECH_COMPOSITE GSS_C_MA_MECH_NEGO GSS_C_MA_MECH_GLUE GSS_C_MA_NOT_MECH GSS_C_MA_DEPRECATED GSS_C_MA_NOT_DFLT_MECH GSS_C_MA_ITOK_FRAMED GSS_C_MA_AUTH_INIT GSS_C_MA_AUTH_TARG GSS_C_MA_AUTH_INIT_INIT GSS_C_MA_AUTH_TARG_INIT GSS_C_MA_AUTH_INIT_ANON GSS_C_MA_AUTH_TARG_ANON GSS_C_MA_DELEG_CRED GSS_C_MA_INTEG_PROT GSS_C_MA_CONF_PROT GSS_C_MA_MIC GSS_C_MA_WRAP GSS_C_MA_PROT_READY GSS_C_MA_REPLAY_DET GSS_C_MA_OOS_DET GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS