server/login.c

   1 /**
   2  * @file login.c
   3  * @brief Implementation of Login related functionality
   4  */
   5
   6
   7
   8
   9 #include "login.h"
  10 #include "options.h"
  11 #include <ctype.h>
  12 #include <unistd.h>
  13
  14 #define LDAP_DEPRECATED 1 // Required to use ldap_simple_bind_s
  15 #include <ldap.h>
  16
  17 /**
  18  * Attempt to login using a file formatted like /etc/shadow
  19  * This is here... because all better options have been exhausted
  20  * @param user - The username
  21  * @param pass - The password
  22  * @returns Privelage level of the user or USER_UNAUTH for failure to authenticate
  23  */
  24 UserType Login_Shadow(const char * user, const char * pass, const char * shadow)
  25 {
  26         if (strlen(user) + strlen(pass) >= BUFSIZ-1)
  27         {
  28                 Log(LOGERR, "User/Password too long!\n");
  29                 return USER_UNAUTH;
  30         }
  31
  32         FILE * f = fopen(shadow, "r");
  33         if (f == NULL)
  34         {
  35                 Log(LOGERR,"Can't open %s - %s\n", shadow, strerror(errno));
  36                 return USER_UNAUTH;
  37         }
  38
  39         char buffer[BUFSIZ];
  40         int passwd_index = -1;
  41
  42         while (fgets(buffer, BUFSIZ, f) != NULL) // NOTE: Restrict username+password strings to BUFSIZ... what could possibly go wrong?
  43         {
  44
  45                 //Log(LOGDEBUG,"Scanning %d: %s", strlen(buffer), buffer);
  46
  47                 for (int i = 0; i < BUFSIZ-1 && buffer[i] != '\0'; ++i)
  48                 {
  49                         if (buffer[i] == ':')
  50                         {
  51                                 buffer[i] = '\0';
  52                                 passwd_index = i+1;
  53                                 break;
  54                         }
  55                 }
  56
  57                 if (strcmp(user,buffer) == 0)
  58                 {
  59                         //Log(LOGDEBUG,"User matches! %s\n", buffer);
  60                         break;
  61                 }
  62                 passwd_index = -1;
  63         }
  64
  65         if (passwd_index <= 0)
  66         {
  67                 //Log(LOGDEBUG,"No user found matching %s\n", user);
  68                 return USER_UNAUTH;
  69         }
  70
  71         int gid_index = -1;
  72         for (int i = passwd_index; i < BUFSIZ-1 && buffer[i] != '\0'; ++i)
  73         {
  74                 if (buffer[i] == ':')
  75                 {
  76                         gid_index = i+1;
  77                         buffer[i] = '\0';
  78                 }
  79                 if (buffer[i] == '\n')
  80                         buffer[i] = '\0';
  81         }
  82         char * end = buffer+gid_index;
  83         UserType user_type = USER_NORMAL;
  84         if (gid_index > passwd_index && gid_index < BUFSIZ-1)
  85         {
  86                 int gid = strtol(buffer+gid_index, &end,10);
  87                 Log(LOGDEBUG, "Usertype %d %s", gid, buffer+gid_index);
  88                 if (*end == '\0' && gid == 0)
  89                 {
  90                         Log(LOGDEBUG, "Admin");
  91                         user_type = USER_ADMIN;
  92                 }
  93         }
  94
  95         // Determine the salt
  96         char salt[BUFSIZ];
  97         int s = 0; int count = 0;
  98         for (int i = passwd_index; i < BUFSIZ-1; ++i)
  99         {
 100                 salt[s++] = buffer[i];
 101                 if (salt[s] == '$' && ++count >= 3)
 102                         break;
 103         }
 104
 105 //      Log(LOGDEBUG,"Salted Entry: %s\n", buffer+passwd_index);
 106 //      Log(LOGDEBUG,"Salted Attempt: %s\n", crypt(pass, salt));
 107
 108         if (strcmp(crypt(pass, salt), buffer+passwd_index) == 0)
 109         {
 110                 return user_type;
 111         }
 112         return USER_UNAUTH;
 113 }
 114
 115 /**
 116  * Attempt to bind to a LDAP uri
 117  * @param uri - The uri
 118  * @param dn - The DN
 119  * @param pass - The password
 120  * @returns An error code according to libldap; LDAP_SUCCESS if everything worked
 121  */
 122 int Login_LDAP_Bind(const char * uri, const char * dn, const char * pass)
 123 {
 124         Log(LOGDEBUG, "Bind to %s with dn %s and pass %s", uri, dn, pass);
 125
 126         // Initialise LDAP; prepares to connect to the server
 127         LDAP * ld = NULL;
 128         int err = ldap_initialize(&ld, uri);
 129         if (err != LDAP_SUCCESS || ld == NULL)
 130         {
 131                 Log(LOGERR,"ldap_initialize failed - %s (ld = %p)", ldap_err2string(err), ld);
 132                 return err;
 133         }
 134
 135         // Set the LDAP version...
 136         int version = LDAP_VERSION3;
 137         err = ldap_set_option(ld, LDAP_OPT_PROTOCOL_VERSION, &version); // specify the version
 138         if (err != LDAP_SUCCESS)
 139         {
 140                 Log(LOGERR,"ldap_set_option failed - %s", ldap_err2string(err));
 141                 return err;
 142         }
 143
 144         // Attempt to bind using the supplied credentials.
 145         // NOTE: ldap_simple_bind_s is "deprecated" in <ldap.h>, but not listed as such in the man pages :S
 146         err = ldap_simple_bind_s(ld, dn, pass);
 147         if (err != LDAP_SUCCESS)
 148         {
 149                 Log(LOGERR, "ldap_simple_bind_s failed - %s", ldap_err2string(err));
 150         }
 151         else
 152         {
 153                 Log(LOGDEBUG, "Successfully bound to %s with dn %s", uri, dn);
 154         }
 155
 156         int err2 = ldap_unbind_s(ld);
 157         if (err2 != LDAP_SUCCESS)
 158         {
 159                 Log(LOGERR, "ldap_unbind_s failed - %s", ldap_err2string(err2));
 160                 err = err2;
 161         }
 162         return err;
 163 }
 164
 165 /**
 166  * Logout
 167  * @param context - The context. The key will be cleared.
 168  * @param params - Parameter string, UNUSED
 169  */
 170 void Logout_Handler(FCGIContext * context, char * params)
 171 {
 172         FCGI_ReleaseControl(context);
 173         FCGI_SendControlCookie(context, false); //Unset the cookie
 174         FCGI_AcceptJSON(context, "Logged out");
 175 }
 176
 177
 178 /**
 179  * Handle a Login Request
 180  * @param context - The context
 181  * @param params - Parameter string, should contain username and password
 182  */
 183 void Login_Handler(FCGIContext * context, char * params)
 184 {
 185         char * user; // The username supplied through CGI
 186         char * pass; // The password supplied through CGI
 187
 188         FCGIValue values[] = {
 189                 {"user", &user, FCGI_REQUIRED(FCGI_STRING_T)},
 190                 {"pass", &pass, FCGI_REQUIRED(FCGI_STRING_T)},
 191         };
 192
 193         //enum to avoid the use of magic numbers
 194         typedef enum {
 195                 USER,
 196                 PASS,
 197                 LOGOUT
 198         } LoginParams;
 199
 200         // Fill values appropriately
 201         if (!FCGI_ParseRequest(context, params, values, sizeof(values)/sizeof(FCGIValue)))
 202         {
 203                 // Error occured; FCGI_RejectJSON already called
 204                 return;
 205         }
 206
 207         // Trim leading whitespace
 208         int i = 0;
 209         for (i = 0; isspace(user[0]) && user[0] != '\0'; ++i, ++user);
 210
 211         // Truncate string at first non alphanumeric character
 212         for (i = 0; isalnum(user[i]) && user[i] != '\0'; ++i);
 213         user[i] = '\0';
 214
 215
 216         UserType user_type = USER_UNAUTH;
 217
 218         switch (g_options.auth_method)
 219         {
 220
 221                 case AUTH_LDAP:
 222                 {
 223                         if (strlen(pass) <= 0)
 224                         {
 225                                 FCGI_RejectJSON(context, "No password supplied.");
 226                                 return;
 227                         }
 228
 229                         //TODO: Generate the DN in some sane way
 230                         char dn[BUFSIZ];
 231
 232                         // On a simple LDAP server:
 233                         //int len = sprintf(dn, "uid=%s,%s", user, g_options.ldap_base_dn);
 234
 235                         // At UWA (hooray)
 236                         char * user_group = "Students";
 237                         if (user[0] == '0')
 238                                 user_group = "Staff";
 239                         int len = sprintf(dn, "cn=%s,ou=%s,%s", user, user_group, g_options.ldap_base_dn);
 240
 241
 242                         if (len >= BUFSIZ)
 243                         {
 244                                 FCGI_RejectJSON(context, "DN too long! Recompile with increased BUFSIZ");
 245                                 return;
 246                         }
 247
 248                         if (Login_LDAP_Bind(g_options.auth_uri, dn, pass) == LDAP_SUCCESS)
 249                         {
 250                                 if (user[0] == '0')
 251                                         user_type = USER_ADMIN;
 252                                 else
 253                                         user_type = USER_NORMAL;
 254                         }
 255                         break;
 256                 }
 257                 case AUTH_SHADOW:
 258                 {
 259                         user_type = Login_Shadow(user, pass, g_options.auth_uri);
 260                         break;
 261                 }
 262                 default:
 263                 {
 264                         Log(LOGWARN, "No authentication!");
 265                         user_type = USER_ADMIN;
 266                         break;
 267                 }
 268         }
 269
 270         // error check
 271
 272         if (user_type == USER_UNAUTH)
 273         {
 274                 Log(LOGDEBUG, "Authentication failure for %s", user);
 275                 FCGI_RejectJSONEx(context, STATUS_UNAUTHORIZED, "Authentication failure.");
 276         }
 277         else
 278         {
 279                 // Try and gain control over the system
 280                 if (FCGI_LockControl(context, user, user_type))
 281                 {
 282                         FCGI_EscapeText(context->user_name); //Don't break javascript pls
 283                         // Give the user a cookie
 284                         FCGI_SendControlCookie(context, true); //Send the control key
 285                         FCGI_AcceptJSON(context, "Logged in");
 286                         Log(LOGDEBUG, "Successful authentication for %s", user);
 287                 }
 288                 else
 289                 {
 290                         Log(LOGDEBUG, "%s successfully authenticated but system was in use by %s", user, context->user_name);
 291                         FCGI_RejectJSON(context, "Someone else is already logged in (and you are not an admin)");
 292                 }
 293         }
 294 }