| 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 | |
| 49 | struct 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 | |
| 60 | static 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 | |
| 122 | static 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 | |
| 142 | static void release(struct authhandle *auth) |
| 143 | { |
| 144 | releasepam((struct pamdata *)auth->mechdata); |
| 145 | } |
| 146 | |
| 147 | static 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 | |
| 160 | static 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 | |
| 188 | static 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 | |
| 198 | static 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 | |
| 251 | static 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 | |
| 267 | static 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 | |
| 295 | static 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 | |
| 322 | struct 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 | }; |