1 /*
2 * Copyright (c) 1999-2004 Todd C. Miller <Todd.Miller@courtesan.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 *
16 * Sponsored in part by the Defense Advanced Research Projects
17 * Agency (DARPA) and Air Force Research Laboratory, Air Force
18 * Materiel Command, USAF, under agreement number F39502-99-1-0512.
19 */
20
21 #include "config.h"
22
23 #include <sys/types.h>
24 #include <sys/param.h>
25 #include <stdio.h>
26 #ifdef STDC_HEADERS
27 # include <stdlib.h>
28 # include <stddef.h>
29 #else
30 # ifdef HAVE_STDLIB_H
31 # include <stdlib.h>
32 # endif
33 #endif /* STDC_HEADERS */
34 #ifdef HAVE_STRING_H
35 # if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS)
36 # include <memory.h>
37 # endif
38 # include <string.h>
39 #else
40 # ifdef HAVE_STRINGS_H
41 # include <strings.h>
42 # endif
43 #endif /* HAVE_STRING_H */
44 #ifdef HAVE_UNISTD_H
45 # include <unistd.h>
46 #endif /* HAVE_UNISTD_H */
47 #include <pwd.h>
48
49 #ifdef HAVE_PAM_PAM_APPL_H
50 # include <pam/pam_appl.h>
51 #else
52 # include <security/pam_appl.h>
53 #endif
54
55 #include "sudo.h"
56 #include "sudo_auth.h"
57
58 /* Only OpenPAM and Linux PAM use const qualifiers. */
59 #if defined(_OPENPAM) || defined(__LIBPAM_VERSION)
60 # define PAM_CONST const
61 #else
62 # define PAM_CONST
63 #endif
64
65 #ifndef lint
66 static const char rcsid[] = "$Sudo: pam.c,v 1.43 2004/06/28 14:51:50 millert Exp $";
67 #endif /* lint */
68
69 static int sudo_conv __P((int, PAM_CONST struct pam_message **,
70 struct pam_response **, VOID *));
71 static char *def_prompt;
72
73 #ifndef PAM_DATA_SILENT
74 #define PAM_DATA_SILENT 0
75 #endif
76
77 static pam_handle_t *pamh; /* global due to pam_prep_user() */
78
79 int
pam_init(pw,promptp,auth)80 pam_init(pw, promptp, auth)
81 struct passwd *pw;
82 char **promptp;
83 sudo_auth *auth;
84 {
85 static struct pam_conv pam_conv;
86 static int pam_status;
87
88 /* Initial PAM setup */
89 if (auth != NULL)
90 auth->data = (VOID *) &pam_status;
91 pam_conv.conv = sudo_conv;
92 pam_status = pam_start("sudo", pw->pw_name, &pam_conv, &pamh);
93 if (pam_status != PAM_SUCCESS) {
94 log_error(USE_ERRNO|NO_EXIT|NO_MAIL, "unable to initialize PAM");
95 return(AUTH_FATAL);
96 }
97 if (strcmp(user_tty, "unknown"))
98 (void) pam_set_item(pamh, PAM_TTY, user_tty);
99
100 return(AUTH_SUCCESS);
101 }
102
103 int
pam_verify(pw,prompt,auth)104 pam_verify(pw, prompt, auth)
105 struct passwd *pw;
106 char *prompt;
107 sudo_auth *auth;
108 {
109 const char *s;
110 int *pam_status = (int *) auth->data;
111
112 def_prompt = prompt; /* for sudo_conv */
113
114 /* PAM_SILENT prevents the authentication service from generating output. */
115 *pam_status = pam_authenticate(pamh, PAM_SILENT);
116 switch (*pam_status) {
117 case PAM_SUCCESS:
118 *pam_status = pam_acct_mgmt(pamh, PAM_SILENT);
119 switch (*pam_status) {
120 case PAM_SUCCESS:
121 return(AUTH_SUCCESS);
122 case PAM_AUTH_ERR:
123 log_error(NO_EXIT|NO_MAIL, "pam_acct_mgmt: %d",
124 *pam_status);
125 return(AUTH_FAILURE);
126 case PAM_NEW_AUTHTOK_REQD:
127 log_error(NO_EXIT|NO_MAIL, "%s, %s",
128 "Account or password is expired",
129 "reset your password and try again");
130 *pam_status = pam_chauthtok(pamh,
131 PAM_CHANGE_EXPIRED_AUTHTOK);
132 if (*pam_status == PAM_SUCCESS)
133 return(AUTH_SUCCESS);
134 if ((s = pam_strerror(pamh, *pam_status)))
135 log_error(NO_EXIT|NO_MAIL, "pam_chauthtok: %s", s);
136 return(AUTH_FAILURE);
137 case PAM_AUTHTOK_EXPIRED:
138 log_error(NO_EXIT|NO_MAIL,
139 "Password expired, contact your system administrator");
140 return(AUTH_FATAL);
141 case PAM_ACCT_EXPIRED:
142 log_error(NO_EXIT|NO_MAIL, "%s %s",
143 "Account expired or PAM config lacks an \"account\"",
144 "section for sudo, contact your system administrator");
145 return(AUTH_FATAL);
146 }
147 /* FALLTHROUGH */
148 case PAM_AUTH_ERR:
149 case PAM_MAXTRIES:
150 case PAM_PERM_DENIED:
151 return(AUTH_FAILURE);
152 default:
153 if ((s = pam_strerror(pamh, *pam_status)))
154 log_error(NO_EXIT|NO_MAIL, "pam_authenticate: %s", s);
155 return(AUTH_FATAL);
156 }
157 }
158
159 int
pam_cleanup(pw,auth)160 pam_cleanup(pw, auth)
161 struct passwd *pw;
162 sudo_auth *auth;
163 {
164 int *pam_status = (int *) auth->data;
165
166 /* If successful, we can't close the session until pam_prep_user() */
167 if (auth->status == AUTH_SUCCESS)
168 return(AUTH_SUCCESS);
169
170 *pam_status = pam_end(pamh, *pam_status | PAM_DATA_SILENT);
171 return(*pam_status == PAM_SUCCESS ? AUTH_SUCCESS : AUTH_FAILURE);
172 }
173
174 int
pam_prep_user(pw)175 pam_prep_user(pw)
176 struct passwd *pw;
177 {
178 if (pamh == NULL)
179 pam_init(pw, NULL, NULL);
180
181 /*
182 * Set PAM_USER to the user we are changing *to* and
183 * set PAM_RUSER to the user we are coming *from*.
184 */
185 (void) pam_set_item(pamh, PAM_USER, pw->pw_name);
186 (void) pam_set_item(pamh, PAM_RUSER, user_name);
187
188 /*
189 * Set credentials (may include resource limits, device ownership, etc).
190 * We don't check the return value here because in Linux-PAM 0.75
191 * it returns the last saved return code, not the return code
192 * for the setcred module. Because we haven't called pam_authenticate(),
193 * this is not set and so pam_setcred() returns PAM_PERM_DENIED.
194 * We can't call pam_acct_mgmt() with Linux-PAM for a similar reason.
195 */
196 (void) pam_setcred(pamh, PAM_ESTABLISH_CRED);
197
198 if (pam_end(pamh, PAM_SUCCESS | PAM_DATA_SILENT) == PAM_SUCCESS)
199 return(AUTH_SUCCESS);
200 else
201 return(AUTH_FAILURE);
202 }
203
204 /*
205 * ``Conversation function'' for PAM.
206 * XXX - does not handle PAM_BINARY_PROMPT
207 */
208 static int
sudo_conv(num_msg,msg,response,appdata_ptr)209 sudo_conv(num_msg, msg, response, appdata_ptr)
210 int num_msg;
211 PAM_CONST struct pam_message **msg;
212 struct pam_response **response;
213 VOID *appdata_ptr;
214 {
215 struct pam_response *pr;
216 PAM_CONST struct pam_message *pm;
217 const char *p = def_prompt;
218 char *pass;
219 int n, flags;
220 extern int nil_pw;
221
222 if ((*response = malloc(num_msg * sizeof(struct pam_response))) == NULL)
223 return(PAM_CONV_ERR);
224 zero_bytes(*response, num_msg * sizeof(struct pam_response));
225
226 for (pr = *response, pm = *msg, n = num_msg; n--; pr++, pm++) {
227 flags = tgetpass_flags;
228 switch (pm->msg_style) {
229 case PAM_PROMPT_ECHO_ON:
230 SET(flags, TGP_ECHO);
231 case PAM_PROMPT_ECHO_OFF:
232 /* Only override PAM prompt if it matches /^Password: ?/ */
233 if (strncmp(pm->msg, "Password:", 9) || (pm->msg[9] != '\0'
234 && (pm->msg[9] != ' ' || pm->msg[10] != '\0')))
235 p = pm->msg;
236 /* Read the password. */
237 pass = tgetpass(p, def_passwd_timeout * 60, flags);
238 pr->resp = estrdup(pass ? pass : "");
239 if (*pr->resp == '\0')
240 nil_pw = 1; /* empty password */
241 else
242 zero_bytes(pass, strlen(pass));
243 break;
244 case PAM_TEXT_INFO:
245 if (pm->msg)
246 (void) puts(pm->msg);
247 break;
248 case PAM_ERROR_MSG:
249 if (pm->msg) {
250 (void) fputs(pm->msg, stderr);
251 (void) fputc('\n', stderr);
252 }
253 break;
254 default:
255 /* Zero and free allocated memory and return an error. */
256 for (pr = *response, n = num_msg; n--; pr++) {
257 if (pr->resp != NULL) {
258 zero_bytes(pr->resp, strlen(pr->resp));
259 free(pr->resp);
260 pr->resp = NULL;
261 }
262 }
263 zero_bytes(*response, num_msg * sizeof(struct pam_response));
264 free(*response);
265 *response = NULL;
266 return(PAM_CONV_ERR);
267 }
268 }
269
270 return(PAM_SUCCESS);
271 }
272