helpers/basic_auth/PAM/basic_pam_auth.cc

   1 /*
   2  * PAM authenticator module for Squid.
   3  * Copyright (C) 1999,2002,2003 Henrik Nordstrom <hno@squid-cache.org>
   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, USA.
  18  *
  19  * Install instructions:
  20  *
  21  * This program authenticates users against a PAM configured authentication
  22  * service "squid". This allows you to authenticate Squid users to any
  23  * authentication source for which you have a PAM module. Commonly available
  24  * PAM modules includes "UNIX", RADIUS, Kerberos and SMB, but a lot of other
  25  * PAM modules are available from various sources.
  26  *
  27  * Example PAM configuration for standard UNIX passwd authentication:
  28  * /etc/pam.conf:
  29  *  squid auth     required /lib/security/pam_unix.so.1
  30  *  squid account  required /lib/security/pam_unix.so.1
  31  *
  32  * Note that some PAM modules (for example shadow password authentication)
  33  * requires the program to be installed suid root to gain access to the
  34  * user password database
  35  *
  36  * Change Log:
  37  *
  38  *   Version 2.3, 2009-11-06
  39  *      Converted to C++. Brought into line with Squid-3 code styles.
  40  *
  41  *   Version 2.2, 2003-11-05
  42  *      One shot mode is now the default mode of operation
  43  *      with persistent PAM connections enabled by -t option.
  44  *      Support for clearing the PAM_AUTHTOK attribute on
  45  *      persistent PAM connections.
  46  *
  47  *   Version 2.1, 2002-08-12
  48  *      Squid-2.5 support (URL encoded login, password strings)
  49  *
  50  *   Version 2.0, 2002-01-07
  51  *      One shot mode, command line options
  52  *      man page
  53  *
  54  *   Version 1.3, 1999-12-10
  55  *      Bugfix release 1.3 to work around Solaris 2.6
  56  *      brokenness (not sending arguments to conversation
  57  *      functions)
  58  *
  59  *   Version 1.2, internal release
  60  *
  61  *   Version 1.1, 1999-05-11
  62  *      Initial version
  63  *
  64  * Compile this program with: gcc -o basic_pam_auth basic_pam_auth.cc -lpam -ldl
  65  */
  66 #include "squid.h"
  67 #include "helpers/defines.h"
  68 #include "rfc1738.h"
  69 #include "util.h"
  70
  71 #if HAVE_STDIO_H
  72 #include <stdio.h>
  73 #endif
  74 #if HAVE_ASSERT_H
  75 #include <assert.h>
  76 #endif
  77 #if HAVE_STRING_H
  78 #include <string.h>
  79 #endif
  80 #if HAVE_SIGNAL_H
  81 #include <signal.h>
  82 #endif
  83 #if HAVE_TIME_H
  84 #include <time.h>
  85 #endif
  86 #if HAVE_UNISTD_H
  87 #include <unistd.h>
  88 #endif
  89 #if HAVE_SECURITY_PAM_APPL_H
  90 #include <security/pam_appl.h>
  91 #endif
  92
  93 /* The default PAM service name */
  94 #if !defined(DEFAULT_SQUID_PAM_SERVICE)
  95 #define DEFAULT_SQUID_PAM_SERVICE "squid"
  96 #endif
  97
  98 /* The default TTL */
  99 #if !defined(DEFAULT_SQUID_PAM_TTL)
 100 #define DEFAULT_SQUID_PAM_TTL 0
 101 #endif
 102
 103 #if _SQUID_SOLARIS_
 104 static char *password = NULL;   /* Workaround for Solaris 2.6 brokenness */
 105 #endif
 106
 107 extern "C" int password_conversation(int num_msg, PAM_CONV_FUNC_CONST_PARM struct pam_message **msg,
 108                                      struct pam_response **resp, void *appdata_ptr);
 109
 110 /**
 111  * A simple "conversation" function returning the supplied password.
 112  * Has a bit to much error control, but this is my first PAM application
 113  * so I'd rather check everything than make any mistakes. The function
 114  * expects a single converstation message of type PAM_PROMPT_ECHO_OFF.
 115  */
 116 int
 117 password_conversation(int num_msg, PAM_CONV_FUNC_CONST_PARM struct pam_message **msg, struct pam_response **resp, void *appdata_ptr)
 118 {
 119     if (num_msg != 1 || msg[0]->msg_style != PAM_PROMPT_ECHO_OFF) {
 120         debug("ERROR: Unexpected PAM converstaion '%d/%s'\n", msg[0]->msg_style, msg[0]->msg);
 121         return PAM_CONV_ERR;
 122     }
 123 #if _SQUID_SOLARIS_
 124     if (!appdata_ptr) {
 125         /* Workaround for Solaris 2.6 where the PAM library is broken
 126          * and does not pass appdata_ptr to the conversation routine
 127          */
 128         appdata_ptr = password;
 129     }
 130 #endif
 131     if (!appdata_ptr) {
 132         debug("ERROR: No password available to password_converstation!\n");
 133         return PAM_CONV_ERR;
 134     }
 135     *resp = static_cast<struct pam_response *>(calloc(num_msg, sizeof(struct pam_response)));
 136     if (!*resp) {
 137         debug("ERROR: Out of memory!\n");
 138         return PAM_CONV_ERR;
 139     }
 140     (*resp)[0].resp = xstrdup((char *) appdata_ptr);
 141     (*resp)[0].resp_retcode = 0;
 142
 143     return ((*resp)[0].resp ? PAM_SUCCESS : PAM_CONV_ERR);
 144 }
 145
 146 static struct pam_conv conv = {
 147     &password_conversation,
 148     NULL
 149 };
 150
 151 static void usage(char *program)
 152 {
 153     fprintf(stderr, "Usage: %s [options..]\n", program);
 154     fprintf(stderr, " -n service_name\n");
 155     fprintf(stderr, "           The PAM service name (default \"%s\")\n", DEFAULT_SQUID_PAM_SERVICE);
 156     fprintf(stderr, " -t ttl    PAM connection ttl in seconds (default %d)\n", DEFAULT_SQUID_PAM_TTL);
 157     fprintf(stderr, "           during this time the same connection will be reused\n");
 158     fprintf(stderr, "           to authenticate all users\n");
 159     fprintf(stderr, " -o        Do not perform account mgmt (account expiration etc)\n");
 160     fprintf(stderr, " -1        Only one user authentication per PAM connection\n");
 161     fprintf(stderr, " -r        Detect and remove Negotiate/NTLM realm from username\n");
 162 }
 163
 164 int
 165 main(int argc, char *argv[])
 166 {
 167     pam_handle_t *pamh = NULL;
 168     int retval = PAM_SUCCESS;
 169     char *user;
 170     char *password_buf;
 171     char buf[HELPER_INPUT_BUFFER];
 172     time_t pamh_created = 0;
 173     int ttl = DEFAULT_SQUID_PAM_TTL;
 174     const char *service = DEFAULT_SQUID_PAM_SERVICE;
 175     int no_acct_mgmt = 0;
 176     int no_realm = 0;
 177
 178     /* make standard output line buffered */
 179     setvbuf(stdout, NULL, _IOLBF, 0);
 180
 181     while (1) {
 182         int ch = getopt(argc, argv, "1n:t:or");
 183         switch (ch) {
 184         case -1:
 185             goto start;
 186         case 'n':
 187             service = optarg;
 188             break;
 189         case 't':
 190             ttl = atoi(optarg);
 191             break;
 192         case '1':
 193             ttl = 0;
 194             break;
 195         case 'o':
 196             no_acct_mgmt = 1;
 197             break;
 198         case 'r':
 199             no_realm = 1;
 200             break;
 201         default:
 202             fprintf(stderr, "FATAL: Unknown getopt value '%c'\n", ch);
 203             usage(argv[0]);
 204             exit(1);
 205         }
 206     }
 207 start:
 208     if (optind < argc) {
 209         fprintf(stderr, "FATAL: Unknown option '%s'\n", argv[optind]);
 210         usage(argv[0]);
 211         exit(1);
 212     }
 213
 214     while (fgets(buf, HELPER_INPUT_BUFFER, stdin)) {
 215         user = buf;
 216         password_buf = strchr(buf, '\n');
 217         if (!password_buf) {
 218             debug("ERROR: %s: Unexpected input '%s'\n", argv[0], buf);
 219             goto error;
 220         }
 221         *password_buf = '\0';
 222         password_buf = strchr(buf, ' ');
 223         if (!password_buf) {
 224             debug("ERROR: %s: Unexpected input '%s'\n", argv[0], buf);
 225             goto error;
 226         }
 227         *password_buf = '\0';
 228         ++password_buf;
 229         rfc1738_unescape(user);
 230         rfc1738_unescape(password_buf);
 231         conv.appdata_ptr = (char *) password_buf;       /* from buf above. not allocated */
 232
 233         if (no_realm) {
 234             /* Remove DOMAIN\.. and ...@domain from the user name in case the user
 235              * thought this was an NTLM or Negotiate authentication popup box
 236              */
 237             char * user_ptr = strchr(user, '@');
 238             if (user_ptr) *user_ptr = 0;
 239             else {
 240                 user_ptr = strchr(user, '\\');
 241                 if (user_ptr) user = user_ptr + 1;
 242             }
 243         }
 244
 245 #if _SQUID_SOLARIS_
 246         /* Workaround for Solaris 2.6 where the PAM library is broken
 247          * and does not pass appdata_ptr to the conversation routine
 248          */
 249         password = password_buf;
 250 #endif
 251         if (ttl == 0) {
 252             /* Create PAM connection */
 253             retval = pam_start(service, user, &conv, &pamh);
 254             if (retval != PAM_SUCCESS) {
 255                 debug("ERROR: failed to create PAM authenticator\n");
 256                 goto error;
 257             }
 258         } else if (!pamh || (time(NULL) - pamh_created) >= ttl || pamh_created > time(NULL)) {
 259             /* Close previous PAM connection */
 260             if (pamh) {
 261                 retval = pam_end(pamh, retval);
 262                 if (retval != PAM_SUCCESS) {
 263                     debug("WARNING: failed to release PAM authenticator\n");
 264                 }
 265                 pamh = NULL;
 266             }
 267             /* Initialize persistent PAM connection */
 268             retval = pam_start(service, "squid@", &conv, &pamh);
 269             if (retval != PAM_SUCCESS) {
 270                 debug("ERROR: failed to create PAM authenticator\n");
 271                 goto error;
 272             }
 273             pamh_created = time(NULL);
 274         }
 275         /* Authentication */
 276         retval = PAM_SUCCESS;
 277         if (ttl != 0) {
 278             retval = pam_set_item(pamh, PAM_USER, user);
 279             if (retval == PAM_SUCCESS)
 280                 retval = pam_set_item(pamh, PAM_CONV, &conv);
 281         }
 282         if (retval == PAM_SUCCESS)
 283             retval = pam_authenticate(pamh, 0);
 284         if (retval == PAM_SUCCESS && !no_acct_mgmt)
 285             retval = pam_acct_mgmt(pamh, 0);
 286         if (retval == PAM_SUCCESS) {
 287             SEND_OK("");
 288         } else {
 289 error:
 290             SEND_ERR("");
 291         }
 292         /* cleanup */
 293         retval = PAM_SUCCESS;
 294 #if defined(PAM_AUTHTOK)
 295         if (ttl != 0 && pamh) {
 296             retval = pam_set_item(pamh, PAM_AUTHTOK, NULL);
 297         }
 298 #endif
 299         if (pamh && (ttl == 0 || retval != PAM_SUCCESS)) {
 300             retval = pam_end(pamh, retval);
 301             if (retval != PAM_SUCCESS) {
 302                 debug("WARNING: failed to release PAM authenticator\n");
 303             }
 304             pamh = NULL;
 305         }
 306     }
 307
 308     if (pamh) {
 309         retval = pam_end(pamh, retval);
 310         if (retval != PAM_SUCCESS) {
 311             pamh = NULL;
 312             debug("ERROR: failed to release PAM authenticator\n");
 313         }
 314     }
 315     return 0;
 316 }