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[doldaconnect.git] / daemon / auth-pam.c
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d3372da9 1/*
2 * Dolda Connect - Modular multiuser Direct Connect-style client
3 * Copyright (C) 2004 Fredrik Tolf (fredrik@dolda2000.com)
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18*/
19/*
20 * I have decided that I don't like PAM. Maybe I'm inexperienced, so
21 * please correct me if I'm wrong, but is it not so that
22 * pam_authenticate blocks until the user has fully authenticated
23 * herself? That isn't very good in a program that wants to do other
24 * things at the same time. In my mind, pam_authenticate should return
25 * with a conversation struct every time it wants data.
26 *
27 * My solution here, for now, is to use the ucontext context switching
28 * functions to get back and forth from the conversation
29 * function. Ugly? Yes indeed, it most certainly is, but what am I to
30 * do, then? If there actually is a good way to do this that is built
31 * into PAM, _please_, do mail me about it.
32 */
33
34#include <stdlib.h>
35#include <unistd.h>
36#include <string.h>
37#include <ucontext.h>
38#include <security/pam_appl.h>
39#include <errno.h>
40
41#ifdef HAVE_CONFIG_H
42#include <config.h>
43#endif
44#include "auth.h"
45#include "utils.h"
46#include "conf.h"
47#include "log.h"
48
49struct pamdata
50{
51 pam_handle_t *pamh;
52 volatile int pamret;
53 ucontext_t mainctxt, pamctxt;
54 void *pamstack;
55 volatile int validctxt;
56 volatile int convdone, converr;
57 volatile char *passdata;
58};
59
60static int pamconv(int nmsg, const struct pam_message **msg, struct pam_response **resp, struct authhandle *auth)
61{
62 int i;
63 struct pamdata *data;
64
65 data = auth->mechdata;
66 *resp = smalloc(sizeof(**resp) * nmsg);
67 for(i = 0; i < nmsg; i++)
68 {
69 switch(msg[i]->msg_style)
70 {
71 case PAM_PROMPT_ECHO_OFF:
72 auth->prompt = AUTH_PR_NOECHO;
73 break;
74 case PAM_PROMPT_ECHO_ON:
75 auth->prompt = AUTH_PR_ECHO;
76 break;
77 case PAM_ERROR_MSG:
78 auth->prompt = AUTH_PR_ERROR;
79 break;
80 case PAM_TEXT_INFO:
81 auth->prompt = AUTH_PR_INFO;
82 break;
83 }
84 if(auth->text != NULL)
85 free(auth->text);
86 if((auth->text = icmbstowcs((char *)msg[i]->msg, NULL)) == NULL)
87 {
88 flog(LOG_ERR, "could not convert PAM error %s into wcs: %s", msg[i]->msg, strerror(errno));
89 free(*resp);
90 *resp = NULL;
91 return(PAM_CONV_ERR);
92 }
93 if(swapcontext(&data->pamctxt, &data->mainctxt))
94 {
95 flog(LOG_CRIT, "could not swap context in PAM conversation: %s", strerror(errno));
96 free(*resp);
97 *resp = NULL;
98 return(PAM_CONV_ERR);
99 }
100 if(data->converr)
101 {
102 for(; i < nmsg; i++)
103 {
104 (*resp)[i].resp = sstrdup("");
105 (*resp)[i].resp_retcode = PAM_SUCCESS;
106 }
107 return(PAM_CONV_ERR);
108 }
109 switch(msg[i]->msg_style)
110 {
111 case PAM_PROMPT_ECHO_OFF:
112 case PAM_PROMPT_ECHO_ON:
113 (*resp)[i].resp = sstrdup((char *)data->passdata);
114 memset((void *)data->passdata, 0, strlen((char *)data->passdata));
115 (*resp)[i].resp_retcode = PAM_SUCCESS;
116 break;
117 }
118 }
119 return(PAM_SUCCESS);
120}
121
122static void releasepam(struct pamdata *data)
123{
124 if(data->pamh != NULL)
125 {
126 if(data->validctxt)
127 {
128 data->converr = 1;
129 if(swapcontext(&data->mainctxt, &data->pamctxt))
130 {
131 flog(LOG_CRIT, "could not switch back to PAM context while releasing: %s", strerror(errno));
132 return;
133 }
134 }
135 pam_end(data->pamh, data->pamret);
136 }
137 if(data->pamstack != NULL)
138 free(data->pamstack);
139 free(data);
140}
141
142static void release(struct authhandle *auth)
143{
144 releasepam((struct pamdata *)auth->mechdata);
145}
146
147static struct pamdata *newpamdata(void)
148{
149 struct pamdata *new;
150
151 new = smalloc(sizeof(*new));
152 new->pamh = NULL;
153 new->pamret = PAM_SUCCESS;
154 new->pamstack = NULL;
155 new->validctxt = 0;
156 new->converr = 0;
157 return(new);
158}
159
160static int inithandle(struct authhandle *auth, char *username)
161{
162 char *buf;
163 struct pamdata *data;
164 struct pam_conv conv;
165
166 data = newpamdata();
167 conv.conv = (int (*)(int, const struct pam_message **, struct pam_response **, void *))pamconv;
168 conv.appdata_ptr = auth;
169 if((buf = icwcstombs(confgetstr("auth", "pamserv"), NULL)) == NULL)
170 {
171 flog(LOG_ERR, "could not initialize pam since auth.pamserv cannot be translated into the current locale: %s", strerror(errno));
172 releasepam(data);
173 return(1);
174 }
175 if((data->pamret = pam_start(buf, username, &conv, &data->pamh)) != PAM_SUCCESS)
176 {
177 flog(LOG_CRIT, "could not pam_start: %s", pam_strerror(NULL, data->pamret));
178 releasepam(data);
179 free(buf);
180 errno = ENOTSUP; /* XXX */
181 return(1);
182 }
183 free(buf);
184 auth->mechdata = data;
185 return(0);
186}
187
188static void pamauththread(struct authhandle *auth)
189{
190 struct pamdata *data;
191
192 data = (struct pamdata *)auth->mechdata;
193 data->validctxt = 1;
194 data->pamret = pam_authenticate(data->pamh, 0);
195 data->validctxt = 0;
196}
197
198static int pamauth(struct authhandle *auth, char *passdata)
199{
200 struct pamdata *data;
201
202 data = auth->mechdata;
203 if(!data->validctxt)
204 {
205 if(getcontext(&data->pamctxt))
206 {
207 flog(LOG_CRIT, "could not get context: %s", strerror(errno));
208 return(AUTH_ERR);
209 }
210 data->pamctxt.uc_link = &data->mainctxt;
211 if(data->pamstack == NULL)
212 data->pamstack = smalloc(65536);
213 data->pamctxt.uc_stack.ss_sp = data->pamstack;
214 data->pamctxt.uc_stack.ss_size = 65536;
215 makecontext(&data->pamctxt, (void (*)(void))pamauththread, 1, auth);
216 if(swapcontext(&data->mainctxt, &data->pamctxt))
217 {
218 flog(LOG_CRIT, "Could not switch to PAM context: %s", strerror(errno));
219 return(AUTH_ERR);
220 }
221 if(!data->validctxt)
222 {
223 if(data->pamret == PAM_AUTHINFO_UNAVAIL)
224 return(AUTH_ERR);
225 else if(data->pamret == PAM_SUCCESS)
226 return(AUTH_SUCCESS);
227 else
228 return(AUTH_DENIED);
229 }
230 return(AUTH_PASS);
231 } else {
232 data->passdata = passdata;
233 if(swapcontext(&data->mainctxt, &data->pamctxt))
234 {
235 flog(LOG_CRIT, "could not switch back to PAM context: %s", strerror(errno));
236 return(AUTH_ERR);
237 }
238 if(!data->validctxt)
239 {
240 if(data->pamret == PAM_AUTHINFO_UNAVAIL)
241 return(AUTH_ERR);
242 else if(data->pamret == PAM_SUCCESS)
243 return(AUTH_SUCCESS);
244 else
245 return(AUTH_DENIED);
246 }
247 return(AUTH_PASS);
248 }
249}
250
251static int renewcred(struct authhandle *auth)
252{
253 struct pamdata *data;
254
255 data = auth->mechdata;
256 if(data->pamh == NULL)
257 return(AUTH_SUCCESS);
258 data->pamret = pam_setcred(data->pamh, PAM_REFRESH_CRED);
259 if(data->pamret != PAM_SUCCESS)
260 {
261 flog(LOG_INFO, "could not refresh credentials: %s", pam_strerror(data->pamh, data->pamret));
262 return(AUTH_ERR);
263 }
264 return(AUTH_SUCCESS);
265}
266
267static int opensess(struct authhandle *auth)
268{
269 struct pamdata *data;
270 char **envp;
271
272 data = auth->mechdata;
273 if(data->pamh == NULL)
274 {
275 flog(LOG_ERR, "bug: in auth-pam.c:opensess: called with NULL pamh");
276 return(AUTH_ERR);
277 }
278 data->pamret = pam_setcred(data->pamh, PAM_ESTABLISH_CRED);
279 if(data->pamret != PAM_SUCCESS)
280 {
281 flog(LOG_INFO, "could not establish credentials: %s", pam_strerror(data->pamh, data->pamret));
282 return(AUTH_ERR);
283 }
284 data->pamret = pam_open_session(data->pamh, 0);
285 if(data->pamret != PAM_SUCCESS)
286 {
287 flog(LOG_INFO, "could not open session: %s", pam_strerror(data->pamh, data->pamret));
288 return(AUTH_ERR);
289 }
290 for(envp = pam_getenvlist(data->pamh); *envp; envp++)
291 putenv(*envp);
292 return(AUTH_SUCCESS);
293}
294
295static int closesess(struct authhandle *auth)
296{
297 int rc;
298 struct pamdata *data;
299
300 data = auth->mechdata;
301 if(data->pamh == NULL)
302 {
303 flog(LOG_ERR, "bug: in auth-pam.c:closesess: called with NULL pamh");
304 return(AUTH_ERR);
305 }
306 rc = AUTH_SUCCESS;
307 data->pamret = pam_close_session(data->pamh, 0);
308 if(data->pamret != PAM_SUCCESS)
309 {
310 flog(LOG_INFO, "could not open session: %s", pam_strerror(data->pamh, data->pamret));
311 rc = AUTH_ERR;
312 }
313 data->pamret = pam_setcred(data->pamh, PAM_DELETE_CRED);
314 if(data->pamret != PAM_SUCCESS)
315 {
316 flog(LOG_INFO, "could not establish credentials: %s", pam_strerror(data->pamh, data->pamret));
317 rc = AUTH_ERR;
318 }
319 return(rc);
320}
321
322struct authmech authmech_pam =
323{
324 .inithandle = inithandle,
325 .release = release,
326 .authenticate = pamauth,
327 .renewcred = renewcred,
328 .opensess = opensess,
329 .closesess = closesess,
330 .name = L"pam",
331 .enabled = 1
332};