| blob | f2857aaa82a42c03123ef0412d614b7d30bb6980 |
1 .\" Copyright (c) 1998, 2001, 2002, Juniper Networks, Inc.
2 .\" All rights reserved.
3 .\"
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
6 .\" are met:
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\"
13 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 .\" SUCH DAMAGE.
24 .\"
25 .\" $FreeBSD: src/lib/libtacplus/libtacplus.3,v 1.3.2.7 2002/10/09 08:50:42 pst Exp $
26 .\" $DragonFly: src/lib/libtacplus/libtacplus.3,v 1.6 2006/11/11 18:50:04 swildner Exp $
27 .\"
28 .Dd September 2, 1998
29 .Dt LIBTACPLUS 3
30 .Os
31 .Sh NAME
32 .Nm libtacplus
33 .Nd TACACS+ client library
34 .Sh SYNOPSIS
35 .In taclib.h
36 .Ft int
37 .Fn tac_add_server "struct tac_handle *h" "const char *host" "int port" "const char *secret" "int timeout" "int flags"
38 .Ft void
39 .Fn tac_clear_avs "struct tac_handle *h"
40 .Ft void
41 .Fn tac_close "struct tac_handle *h"
42 .Ft int
43 .Fn tac_config "struct tac_handle *h" "const char *path"
44 .Ft int
45 .Fn tac_create_authen "struct tac_handle *h" "int action" "int type" "int service"
46 .Ft int
47 .Fn tac_create_author "struct tac_handle *h" "int method" "int type" "int service"
48 .Ft char *
49 .Fn tac_get_av "struct tac_handle *h" "u_int index"
50 .Ft char *
51 .Fn tac_get_av_value "struct tac_handle *h" "const char *attribute"
52 .Ft void *
53 .Fn tac_get_data "struct tac_handle *h" "size_t *len"
54 .Ft char *
55 .Fn tac_get_msg "struct tac_handle *h"
56 .Ft struct tac_handle *
57 .Fn tac_open "void"
58 .Ft int
59 .Fn tac_send_authen "struct tac_handle *h"
60 .Ft int
61 .Fn tac_send_author "struct tac_handle *h"
62 .Ft int
63 .Fn tac_set_av "struct tac_handle *h" "u_int index" "const char *av_pair"
64 .Ft int
65 .Fn tac_set_data "struct tac_handle *h" "const void *data" "size_t data_len"
66 .Ft int
67 .Fn tac_set_msg "struct tac_handle *h" "const char *msg"
68 .Ft int
69 .Fn tac_set_port "struct tac_handle *h" "const char *port"
70 .Ft int
71 .Fn tac_set_priv "struct tac_handle *h" "int priv"
72 .Ft int
73 .Fn tac_set_rem_addr "struct tac_handle *h" "const char *addr"
74 .Ft int
75 .Fn tac_set_user "struct tac_handle *h" "const char *user"
76 .Ft const char *
77 .Fn tac_strerror "struct tac_handle *h"
78 .Sh DESCRIPTION
79 The
80 .Nm
81 library implements the client side of the TACACS+ network access
82 control protocol. TACACS+ allows clients to perform authentication,
83 authorization, and accounting by means of network requests to remote
84 servers. This library currently supports only the authentication
85 and authorization portion of the protocol.
86 .Sh INITIALIZATION
87 To use the library, an application must first call
88 .Fn tac_open
89 to obtain a
90 .Va struct tac_handle * ,
91 which provides context for subsequent operations.
92 Calls to
93 .Fn tac_open
94 always succeed unless insufficient virtual memory is available. If
95 the necessary memory cannot be allocated,
96 .Fn tac_open
97 returns
98 .Dv NULL .
99 .Pp
100 Before issuing any TACACS+ requests, the library must be made aware
101 of the servers it can contact. The easiest way to configure the
102 library is to call
103 .Fn tac_config .
104 .Fn tac_config
105 causes the library to read a configuration file whose format is
106 described in
107 .Xr tacplus.conf 5 .
108 The pathname of the configuration file is passed as the
109 .Va file
110 argument to
111 .Fn tac_config .
112 This argument may also be given as
113 .Dv NULL ,
114 in which case the standard configuration file
115 .Pa /etc/tacplus.conf
116 is used.
117 .Fn tac_config
118 returns 0 on success, or -1 if an error occurs.
119 .Pp
120 The library can also be configured programmatically by calls to
121 .Fn tac_add_server .
122 The
123 .Va host
124 parameter specifies the server host, either as a fully qualified
125 domain name or as a dotted-quad IP address in text form.
126 The
127 .Va port
128 parameter specifies the TCP port to contact on the server. If
129 .Va port
130 is given as 0, the library uses port 49, the standard TACACS+ port.
131 The shared secret for the server host is passed to the
132 .Va secret
133 parameter. It may be any null-terminated string of bytes.
134 The timeout for receiving replies from the server is passed to the
135 .Va timeout
136 parameter, in units of seconds.
137 The
138 .Va flags
139 parameter is a bit mask of flags to specify various characteristics of
140 the server. It may contain:
141 .Pp
142 .Bl -tag -width Fl
143 .It Dv TAC_SRVR_SINGLE_CONNECT
144 Causes the library to attempt to negotiate single connection mode
145 when communicating with the server. In single connection mode, the
146 original TCP connection is held open for multiple TACACS+ sessions.
147 Older servers do not support this mode, and some of them become
148 confused if the client attempts to negotiate it.
149 .El
150 .Pp
151 .Fn tac_add_server
152 returns 0 on success, or -1 if an error occurs.
153 .Pp
154 .Fn tac_add_server
155 may be called multiple times, and it may be used together with
156 .Fn tac_config .
157 At most 10 servers may be specified.
158 When multiple servers are given, they are tried in round-robin
159 fashion until a working, accessible server is found. Once the
160 library finds such a server, it continues to use it as long as it
161 works.
162 .Sh CREATING A TACACS+ AUTHENTICATION REQUEST
163 To begin constructing a new authentication request, call
164 .Fn tac_create_authen .
165 The
166 .Va action ,
167 .Va type ,
168 and
169 .Va service
170 arguments must be set to appropriate values as defined in the
171 TACACS+ protocol specification. The
172 .In taclib.h
173 header file contains symbolic constants for these values.
174 .Sh CREATING A TACACS+ AUTHORIZATION REQUEST
175 To begin constructing a new authorization request, call
176 .Fn tac_create_author .
177 The
178 .Va method ,
179 .Va type ,
180 and
181 .Va service
182 arguments must be set to appropriate values as defined in the
183 TACACS+ protocol specification. The
184 .In taclib.h
185 header file contains symbolic constants for these values.
186 .Sh SETTING OPTIONAL PARAMETERS ON A REQUEST
187 After creating a request,
188 various optional parameters may be attached to it through calls to
189 .Fn tac_set_av ,
190 .Fn tac_set_data ,
191 .Fn tac_set_port ,
192 .Fn tac_set_priv ,
193 .Fn tac_set_rem_addr ,
194 and
195 .Fn tac_set_user .
196 The library creates its own copies of any strings provided to these
197 functions, so that it is not necessary for the caller to preserve
198 them. By default, each of these parameters is empty except for the
199 privilege level, which defaults to
200 .Ql USER
201 privilege.
202 .Pp
203 .Fn tac_set_av
204 only applies to the context of an authorization request. The format
205 for an attribute value pair is defined in the TACACS+ protocol
206 specification. The index specified can be any value between 0 and
207 255 inclusive and indicates the position in the list to place the
208 attribute value pair. Calling
209 .Fn tac_set_av
210 with same index twice effectively replaces the value at that position.
211 Use
212 .Fn tac_clear_avs
213 to clear all attribute value pairs that may have been set.
214 .Sh SENDING THE AUTHENTICATION REQUEST AND RECEIVING THE RESPONSE
215 After the TACACS+ authentication request has been constructed, it is
216 sent by means of
217 .Fn tac_send_authen .
218 This function connects to a server if not already connected, sends
219 the request, and waits for a reply. On failure,
220 .Fn tac_send_authen
221 returns -1. Otherwise, it returns the TACACS+ status code and flags,
222 packed into an integer value. The status can be extracted using the
223 macro
224 .Fn TAC_AUTHEN_STATUS .
225 Possible status codes, defined in
226 .In taclib.h ,
227 include:
228 .Pp
229 .Bl -item -compact -offset indent
230 .It
231 .Dv TAC_AUTHEN_STATUS_PASS
232 .It
233 .Dv TAC_AUTHEN_STATUS_FAIL
234 .It
235 .Dv TAC_AUTHEN_STATUS_GETDATA
236 .It
237 .Dv TAC_AUTHEN_STATUS_GETUSER
238 .It
239 .Dv TAC_AUTHEN_STATUS_GETPASS
240 .It
241 .Dv TAC_AUTHEN_STATUS_RESTART
242 .It
243 .Dv TAC_AUTHEN_STATUS_ERROR
244 .It
245 .Dv TAC_AUTHEN_STATUS_FOLLOW
246 .El
247 .Pp
248 The only flag is the no-echo flag, which can be tested using the
249 macro
250 .Fn TAC_AUTHEN_NOECHO .
251 .Sh EXTRACTING INFORMATION FROM THE SERVER'S AUTHENTICATION RESPONSE
252 An authentication response packet from the server may contain a
253 server message, a data string, or both. After a successful call to
254 .Fn tac_send_authen ,
255 this information may be retrieved from the response by calling
256 .Fn tac_get_msg
257 and
258 .Fn tac_get_data .
259 These functions return dynamically-allocated copies of the
260 information from the packet. The caller is responsible for freeing
261 the copies when it no longer needs them. The data returned from
262 these functions is guaranteed to be terminated by a null byte.
263 .Pp
264 In the case of
265 .Fn tac_get_data ,
266 the
267 .Va len
268 argument points to a location into which the library will store the
269 actual length of the received data, not including the null
270 terminator. This argument may be given as
271 .Dv NULL
272 if the caller is not interested in the length.
273 .Sh SENDING AUTHENTICATION CONTINUE PACKETS
274 If
275 .Fn tac_send_authen
276 returns a value containing one of the status codes
277 .Dv TAC_AUTHEN_STATUS_GETDATA ,
278 .Dv TAC_AUTHEN_STATUS_GETUSER ,
279 or
280 .Dv TAC_AUTHEN_STATUS_GETPASS ,
281 then the client must provide additional information to the server by
282 means of a TACACS+ CONTINUE packet. To do so, the application must
283 first set the packet's user message and/or data fields using
284 .Fn tac_set_msg
285 and
286 .Fn tac_set_data .
287 The client then sends the CONTINUE packet with
288 .Fn tac_send_authen .
289 N.B.,
290 .Fn tac_create_authen
291 should
292 .Em not
293 be called to construct a CONTINUE packet; it is used only for the
294 initial authentication request.
295 .Pp
296 When it receives the CONTINUE packet, the server may again request
297 more information by returning
298 .Dv TAC_AUTHEN_STATUS_GETDATA ,
299 .Dv TAC_AUTHEN_STATUS_GETUSER ,
300 or
301 .Dv TAC_AUTHEN_STATUS_GETPASS .
302 The application should send further CONTINUEs until some other
303 status is received from the server.
304 .Sh SENDING THE AUTHORIZATION REQUEST AND RECEIVING THE RESPONSE
305 After the TACACS+ authorization request has been constructed, it
306 is sent by means of
307 .Fn tac_send_author .
308 This function connects to a server if not already connected, sends
309 the request, and waits for a reply. On failure,
310 .Fn tac_send_author
311 returns -1. Otherwise, it returns the TACACS+ status code and
312 number of attribute value (AV) pairs received packed into an
313 integer value. The status can be extracted using the macro
314 .Fn TAC_AUTHOR_STATUS .
315 Possible status codes, defined in
316 .In taclib.h ,
317 include:
318 .Pp
319 .Bl -item -compact -offset indent
320 .It
321 .Dv TAC_AUTHOR_STATUS_PASS_ADD
322 .It
323 .Dv TAC_AUTHOR_STATUS_PASS_REPL
324 .It
325 .Dv TAC_AUTHOR_STATUS_FAIL
326 .It
327 .Dv TAC_AUTHOR_STATUS_ERROR
328 .El
329 .Pp
330 The number of AV pairs received is obtained using
331 .Fn TAC_AUTHEN_AV_COUNT .
332 .Sh EXTRACTING INFORMATION FROM THE SERVER'S AUTHORIZATION RESPONSE
333 Like an authentication response packet, an authorization
334 response packet from the
335 server may contain a server message, a data string, or both. Refer
336 to EXTRACTING INFORMATION FROM THE SERVER'S AUTHENTICATION RESPONSE
337 for instruction on extraction of those values.
338 .Pp
339 An authorization response packet from the server may also contain
340 attribute value (AV) pairs. To extract these, use
341 .Fn tac_get_av
342 or
343 .Fn tac_get_av_value .
344 .Fn tac_get_av
345 takes the index of the AV pair as it is positioned in the list.
346 The indexes start at 0 (use
347 .Fn TAC_AUTHEN_AV_COUNT
348 on the return value of
349 .Fn tac_send_author
350 to get the total number of items in this list).
351 Alternatively,
352 .Fn tac_get_av_value
353 can be used.
354 .Fn tac_get_av_value
355 takes the attribute name and returns the
356 corresponding value only, not the AV pair. These functions return
357 dynamically-allocated copies of the information from the packet.
358 The caller is responsible for freeing the copies when it no longer
359 needs them. The data returned from these functions is guaranteed
360 to be terminated by a null byte.
361 .Sh OBTAINING ERROR MESSAGES
362 Those functions which accept a
363 .Va struct tac_handle *
364 argument record an error message if they fail. The error message
365 can be retrieved by calling
366 .Fn tac_strerror .
367 The message text is overwritten on each new error for the given
368 .Va struct tac_handle * .
369 Thus the message must be copied if it is to be preserved through
370 subsequent library calls using the same handle.
371 .Sh CLEANUP
372 To free the resources used by the TACACS+ library, call
373 .Fn tac_close .
374 .Sh RETURN VALUES
375 The following functions return a non-negative value on success. If
376 they detect an error, they return -1 and record an error message
377 which can be retrieved using
378 .Fn tac_strerror .
379 .Pp
380 .Bl -item -offset indent -compact
381 .It
382 .Fn tac_add_server
383 .It
384 .Fn tac_config
385 .It
386 .Fn tac_create_authen
387 .It
388 .Fn tac_create_author
389 .It
390 .Fn tac_send_authen
391 .It
392 .Fn tac_send_author
393 .It
394 .Fn tac_set_av
395 .It
396 .Fn tac_set_data
397 .It
398 .Fn tac_set_msg
399 .It
400 .Fn tac_set_port
401 .It
402 .Fn tac_set_priv
403 .It
404 .Fn tac_set_rem_addr
405 .It
406 .Fn tac_set_user
407 .El
408 .Pp
409 The following functions return a
410 .No non- Ns Dv NULL
411 pointer on success. If they are unable to allocate sufficient
412 virtual memory, they return
413 .Dv NULL
414 and record an error message which can be retrieved using
415 .Fn tac_strerror .
416 .Pp
417 .Bl -item -offset indent -compact
418 .It
419 .Fn tac_get_av
420 .It
421 .Fn tac_get_av_value
422 .It
423 .Fn tac_get_data
424 .It
425 .Fn tac_get_msg
426 .El
427 .Pp
428 The following functions return a
429 .No non- Ns Dv NULL
430 pointer on success. If they are unable to allocate sufficient
431 virtual memory, they return
432 .Dv NULL ,
433 without recording an error message.
434 .Pp
435 .Bl -item -offset indent -compact
436 .It
437 .Fn tac_open
438 .El
439 .Sh FILES
440 .Pa /etc/tacplus.conf
441 .Sh SEE ALSO
442 .Xr tacplus.conf 5
443 .Rs
444 .%A D. Carrel
445 .%A Lol Grant
446 .%T The TACACS+ Protocol, Version 1.78
447 .%O draft-grant-tacacs-02.txt (Internet Draft)
448 .Re
449 .Sh AUTHORS
450 .An -nosplit
451 This software was written by
452 .An John Polstra ,
453 and
454 .An Paul Fraley ,
455 and donated to the
456 .Fx
457 project by Juniper Networks, Inc.