1 2 CDDL HEADER START 3 4 The contents of this file are subject to the terms of the 5 Common Development and Distribution License, Version 1.0 only 6 (the "License"). You may not use this file except in compliance 7 with the License. 8 9 You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 or http://www.opensolaris.org/os/licensing. 11 See the License for the specific language governing permissions 12 and limitations under the License. 13 14 When distributing Covered Code, include this CDDL HEADER in each 15 file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 If applicable, add the following below this CDDL HEADER, with the 17 fields enclosed by brackets "[]" replaced with your own identifying 18 information: Portions Copyright [yyyy] [name of copyright owner] 19 20 CDDL HEADER END 21 22 Copyright 2005 Sun Microsystems, Inc. All rights reserved. 23 Use is subject to license terms. 24 25#ident "%Z%%M% %I% %E% SMI" 26 27 28 The Service Provider Interface for libgss and its Mechanisms 29 ------------------------------------------------------------ 30 31/* CRYPT DELETE START */ 32 331. The libgss SPI upto 11/2004 34 35 Prior to PSARC 2004/810 the libgss SPI consisted of a function 36 provided by each mechanism whose return value is a pointer to a 37 structure full of references to the mechanism's entry points 38 (hereinafter: methods). 39 40 This structure does not include any hooks for versioning, which 41 means that additions of any mechanism methods at micro/patch 42 releases require patching libgss.so.1 and all the GSS mechanisms 43 shipped with Solaris (Kerberos V, DH, SPNEGO). 44 452. The libgss SPI after PSARC 2004/810 46 47 In order to avoid changing the gss_config struct and patching all 48 three mechanisms (four, if the dummy mech counts) and libgss 49 together and in anticipation of a cleaner SPI in the future (see 50 next section) the SPI after PSARC 2004/810 will be as before but 51 supplemented as follows: 52 53 - any new SPI mechanism methods will NOT be placed in gss_config, 54 instead there is a new gss_config_ext structure, which is to be 55 used _only_ by libgss (to avoid struct versioning and/or patch 56 issues), which should be extended to have a pointer to the new 57 method; 58 59 - there is a new libgss function, __gss_get_mechanism_ext(), which 60 is used to get at the gss_config_ext for a mechanism; 61 62 - __gss_get_mechanism_ext() uses dlsym() to build the 63 gss_config_ext struct for the mech by individually loading each 64 and every mechanism method that isn't part of the old gss_config 65 struct -- this happens only once per-method, of course; the 66 result is cached. 67 68 The symbol names that are dlsym()ed are of the form gssspi_* and 69 correspond to gss_*; e.g., gssspi_acquire_cred_with_password(). 70 71 New methods also have a corresponding typedef named 72 <gss_func>_sfct -- the 's' in 'sfct' is for "SPI" and the 'fct' 73 is for "function." This is used to keep cast expressions short. 74 753. The Future libgss SPI 76 77 Once the Solaris krb5 source is resync'ed with MIT krb5 1.4 there 78 will be no further need for the 'void *context' argument to all the 79 libgss mechanisms' methods. 80 81 At that point it will be possible to remove this 'void *context' 82 argument from all the libgss SPI function prototypes, the main 83 result of which will be that the mechanisms' methods will then have 84 the same function signature as the corresponding GSS-API functions. 85 86 We can then rename all mechanisms' methods from <mech>_<gss-func> to 87 <gss-func>. The corresponding typedefs will be renamed to 88 <gss-func>_fct. 89 90 The SPI, then, will be almost exactly the same as the API. 91 92 There will be some minor differences, primarily that some API 93 functions won't have a corresponding SPI method, such as 94 gss_release_buffer(3GSS), for example. 95 96 Some time later we may open the SPI to third party implementors; 97 this could be particularly useful as a way to get access to 3rd 98 party implementations of SPKM and LIPKEY (assuming any ever exist -- 99 SPKM's is a very problematic specification). 100 101 Third party mechanisms should just export all the symbols for the 102 GSS-API functions, like MIT krb5 does, but functions which libgss 103 won't call (e.g., gss_release_buffer(3GSS)) should either not be 104 implemented or should be weak symbols. 105 106 Solaris native mechanisms may still provide the mechanism method 107 registration function as usual for optimization purposes -- to 108 reduce the number of calls to dlsym(). 109 110 Mechanisms that do not provide the old method registration function 111 will be loaded as follows: 112 113 - libgss will look for and find the mechanism's 114 GSS_Indicate_mechs() method and will call it to discover the 115 mechanism provider's mechanism OIDs. 116 117 - libgss will dlsym() each mechanism provider SPI method. 118 119/* CRYPT DELETE END */ 120