nss_afs.c

   1
   2 /*****************************************************************************
   3  * libnss-afs (nss_afs.c)
   4  *
   5  * Copyright 2008, licensed under GNU Library General Public License (LGPL)
   6  * see COPYING file for details
   7  *
   8  * by Adam Megacz <megacz@hcoop.net>
   9  * derived from Frank Burkhardt's libnss_ptdb,
  10  * which was derived from Todd M. Lewis' libnss_pts
  11  *****************************************************************************/
  12
  13 /*
  14  *  If you are reading this code for the first time, read the rest of
  15  *  this comment block, then start at the bottom of the file and work
  16  *  your way upwards.
  17  *
  18  *  All functions which return an int use zero to signal success --
  19  *  except cpstr(), which returns zero on *failure*.  This should be
  20  *  fixed.
  21  *
  22  *  A note about memory allocation:
  23  *
  24  *    NSS plugins generally ought to work without attempting to call
  25  *    malloc() (which may fail).  Therefore, glibc allocates a buffer
  26  *    before calling NSS library functions, and passes that buffer to
  27  *    the NSS library; library functions store their results in the
  28  *    buffer and return pointers into that buffer.
  29  *
  30  *    The convention used throughout this library is to pass around a
  31  *    char** which points to a pointer to the first unused byte in the
  32  *    provided buffer, and a size_t* which points to an int indicating
  33  *    how many bytes are left between the char** and the end of the
  34  *    available region.
  35  */
  36
  37 #include <ctype.h>
  38 #include <err.h>
  39 #include <errno.h>
  40 #include <fcntl.h>
  41 #include <getopt.h>
  42 #include <grp.h>
  43 #include <netinet/in.h>
  44 #include <nss.h>
  45 #include <pthread.h>
  46 #include <pwd.h>
  47 #include <rx/rx.h>
  48 #include <rx/xdr.h>
  49 #include <signal.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <sys/select.h>
  54 #include <sys/socket.h>
  55 #include <sys/time.h>
  56 #include <sys/types.h>
  57 #include <unistd.h>
  58 #include <afs/afs.h>
  59 #include <afs/afsutil.h>
  60 #include <afs/cellconfig.h>
  61 #include <afs/com_err.h>
  62 #include <afs/param.h>
  63 #include <afs/ptclient.h>
  64 #include <afs/pterror.h>
  65 #include <afs/stds.h>
  66
  67 #define HOMEDIR_AUTO      0
  68 #define HOMEDIR_ADMINLINK 1
  69 #define HOMEDIR_PREFIX    2
  70 #define SHELL_BASH        0
  71 #define SHELL_ADMINLINK   1
  72 #define SHELL_USERLINK    2
  73
  74 #define AFS_MAGIC_ANONYMOUS_USERID 32766
  75 #define MIN_PAG_GID                0x41000000L
  76 #define MAX_PAG_GID                0x41FFFFFFL
  77 #define MIN_OLDPAG_GID             0x3f00
  78 #define MAX_OLDPAG_GID             0xff00
  79
  80 #define MAXCELLNAMELEN             256
  81
  82 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  83
  84 extern struct ubik_client *pruclient;
  85
  86 int  afs_initialized = 0;
  87 char cellname[MAXCELLNAMELEN];
  88 char homedir_prefix[MAXPATHLEN];
  89 int  homedir_prefix_len=0;
  90 char homedirs_method=0;
  91 char shells_method=0;
  92
  93 /**
  94  *  The cpstr() function copies a null-terminated string from str*
  95  *  (the first argument) into buf and updates both buf and buflen.  If
  96  *  the string would overflow the buffer, no action is taken.  The
  97  *  number of bytes copied is returned (zero indicates failure).
  98  */
  99 int cpstr( char *str, char **buf, size_t *buflen) {
 100   int len = strlen(str);
 101   if ( len >= *buflen-1 ) return 0;
 102   strcpy(*buf,str);
 103   *buflen -= len + 1;
 104   *buf    += len + 1;
 105   return len;
 106 }
 107
 108 /**
 109  * Look up the name corresponding to uid, store in buffer.
 110  */
 111 enum nss_status ptsid2name(int uid, char **buffer, int *buflen) {
 112   int ret, i;
 113   idlist lid;
 114   namelist lnames;
 115
 116   init_afs();
 117
 118   if (uid==AFS_MAGIC_ANONYMOUS_USERID) {
 119     if (!cpstr("anonymous", buffer, buflen)) return NSS_STATUS_UNAVAIL;
 120     return NSS_STATUS_SUCCESS;
 121   }
 122
 123   if (pthread_mutex_lock(&mutex)) return NSS_STATUS_UNAVAIL;
 124
 125   lid.idlist_val = (afs_int32*)&uid;
 126   lid.idlist_len = 1;
 127   lnames.namelist_val = 0;
 128   lnames.namelist_len = 0;
 129
 130   if (ubik_Call(PR_IDToName,pruclient,0,&lid,&lnames) != PRSUCCESS) {
 131     pthread_mutex_unlock(&mutex);
 132     return NSS_STATUS_UNAVAIL;
 133   }
 134
 135   ret = NSS_STATUS_NOTFOUND;
 136   for (i=0;i<lnames.namelist_len;i++) {
 137     int delta = strlen(lnames.namelist_val[i]);
 138     if ( (delta < buflen) && islower(*(lnames.namelist_val[i])) ) {
 139       cpstr(lnames.namelist_val[i], buffer, buflen);
 140       ret = NSS_STATUS_SUCCESS;
 141     }
 142   }
 143   free(lnames.namelist_val);
 144   /* free(lid.idlist_val); */
 145   lid.idlist_val = 0;
 146   lid.idlist_len = 0;
 147
 148   pthread_mutex_unlock(&mutex);
 149   return ret;
 150 }
 151
 152 /**
 153  * Look up the uid corresponding to name in ptserver.
 154  */
 155 enum nss_status ptsname2id(char *name, uid_t* uid) {
 156   int res;
 157   idlist lid;
 158   namelist lnames;
 159
 160   init_afs();
 161
 162   if (!strcmp(name,"anonymous")) {
 163     *uid = AFS_MAGIC_ANONYMOUS_USERID;
 164     return NSS_STATUS_SUCCESS;
 165   }
 166
 167   if (pthread_mutex_lock(&mutex)) return NSS_STATUS_UNAVAIL;
 168
 169   lid.idlist_val = 0;
 170   lid.idlist_len = 0;
 171   lnames.namelist_val = (prname*)name;
 172   lnames.namelist_len = 1;
 173
 174   if (ubik_Call(PR_NameToID,pruclient,0,&lnames,&lid) != PRSUCCESS) {
 175     pthread_mutex_unlock(&mutex);
 176     return NSS_STATUS_UNAVAIL;
 177   }
 178   pthread_mutex_unlock(&mutex);
 179
 180   res = (uid_t)lid.idlist_val[0];
 181   if (res == AFS_MAGIC_ANONYMOUS_USERID) return NSS_STATUS_NOTFOUND;
 182   *uid = res;
 183   return NSS_STATUS_SUCCESS;
 184 }
 185
 186 /**
 187  *  Initialize the library; returns zero on success
 188  */
 189 int init_afs() {
 190   FILE *thiscell;
 191   int len;
 192
 193   if (afs_initialized) return 0;
 194
 195   if (pthread_mutex_lock(&mutex)) return -1;
 196   do {
 197     homedirs_method=HOMEDIR_PREFIX;
 198     shells_method=SHELL_USERLINK;
 199
 200     len = snprintf(cellname, MAXCELLNAMELEN,
 201                    "%s/ThisCell", AFSDIR_CLIENT_ETC_DIRPATH);
 202     if (len < 0 || len >= MAXCELLNAMELEN) return -1;
 203
 204     thiscell=fopen(cellname,"r");
 205     if (thiscell == NULL) break;
 206     len=fread(cellname,1,MAXCELLNAMELEN,thiscell);
 207     if (!feof(thiscell)) {
 208       // Cellname too long
 209       fclose(thiscell);
 210       strcpy(homedir_prefix,"/tmp/\0");
 211       homedir_prefix_len=5;
 212       break;
 213     }
 214     fclose(thiscell);
 215
 216     if (cellname[len-1] == '\n') len--;
 217     cellname[len]='\0';
 218     sprintf(homedir_prefix,"/afs/%s/user/",cellname);
 219     homedir_prefix_len=strlen(homedir_prefix);
 220
 221     if (pr_Initialize(0L,AFSDIR_CLIENT_ETC_DIRPATH, 0)) break;
 222
 223     afs_initialized = 1;
 224     pthread_mutex_unlock(&mutex);
 225     return 0;
 226
 227   } while(0);
 228   pthread_mutex_unlock(&mutex);
 229   return -1;
 230 }
 231
 232
 233 /**
 234  * Retrieves the homedir for a given user; returns 0 on success.
 235  */
 236 int get_homedir(char *name, char **buffer, size_t *buflen) {
 237   char buf[256];
 238   int temp;
 239   char *b;
 240   b=*buffer;
 241   switch (homedirs_method) {
 242     case HOMEDIR_PREFIX:
 243       homedir_prefix[homedir_prefix_len+0]=name[0];
 244       homedir_prefix[homedir_prefix_len+1]='/';
 245       homedir_prefix[homedir_prefix_len+2]=name[0];
 246       homedir_prefix[homedir_prefix_len+3]=name[1];
 247       homedir_prefix[homedir_prefix_len+4]='/';
 248       homedir_prefix[homedir_prefix_len+5]=0;
 249       strncpy(&homedir_prefix[homedir_prefix_len+5],name,40);
 250       if (! cpstr(homedir_prefix,buffer,buflen) ) return -1;
 251       break;
 252     case HOMEDIR_AUTO:
 253       homedir_prefix[homedir_prefix_len]=0;
 254       strncpy(&homedir_prefix[homedir_prefix_len],name,40);
 255       if (! cpstr(homedir_prefix,buffer,buflen) ) return -1;
 256       break;
 257     case HOMEDIR_ADMINLINK:
 258       if ( snprintf(buf,256,"/afs/%s/admin/homedirs/%s",cellname,name) > 0 ) {
 259         temp=readlink(buf,*buffer,*buflen);
 260         if ( temp > -1) {
 261           b[temp]=0;
 262           *buflen = *buflen - temp - 1;
 263           return -1;
 264         }
 265       }
 266       if (! cpstr("/tmp",buffer,buflen) ) return -1;
 267       break;
 268   }
 269   return 0;
 270 }
 271
 272 /**
 273  * Retrieves the shell for a given user; returns 0 on success.
 274  */
 275 int get_shell(char *name, char **buffer, size_t *buflen) {
 276   char buf[256];
 277   int temp;
 278   char *b;
 279   char* bufx = buf;
 280   int bufxlen = 256;
 281   b=*buffer;
 282
 283   switch (shells_method) {
 284     case SHELL_BASH:
 285       break;
 286
 287     case SHELL_ADMINLINK:
 288       if (snprintf(buf,256,"/afs/%s/admin/shells/%s",cellname,name)<=0) break;
 289       temp = readlink(buf,*buffer,*buflen);
 290       if (temp < 0) break;
 291       b[temp]=0;
 292       *buflen = *buflen - temp - 1;
 293       return 0;
 294
 295     case SHELL_USERLINK:
 296       if (get_homedir(name, &bufx, &bufxlen)) break;
 297       if (strncpy(buf+strlen(buf),"/.loginshell",bufxlen)<=0) break;
 298       temp = readlink(buf,*buffer,*buflen);
 299       if (temp < 0) break;
 300       b[temp]=0;
 301       *buflen = *buflen - temp - 1;
 302       return 0;
 303   }
 304   if (! cpstr("/bin/bash",buffer,buflen) )
 305     return -1;
 306   return 0;
 307 }
 308
 309
 310 /*
 311  * This function is exported; glibc will invoke it in order to find
 312  * the name and list of members of a group specified by a numerical
 313  * groupid.
 314  */
 315 enum nss_status _nss_afs_getgrgid_r (gid_t gid,
 316                                      struct group *result,
 317                                      char *buffer,
 318                                      size_t buflen,
 319                                      int *errnop) {
 320   int length;
 321   int showgid = 0;
 322   if (gid >= MIN_PAG_GID && gid <= MAX_PAG_GID) {
 323     showgid = gid-MIN_PAG_GID;
 324   } else if (gid >= MIN_OLDPAG_GID && gid <= MAX_OLDPAG_GID) {
 325     showgid = gid-MIN_OLDPAG_GID;
 326   } else {
 327     *errnop=ENOENT;
 328     return NSS_STATUS_NOTFOUND;
 329   }
 330   do {
 331     result->gr_gid=gid;
 332
 333     result->gr_name=buffer;
 334     length=snprintf(buffer,buflen,"AfsPag-%x",showgid);
 335
 336     if (length < 0) break;
 337     length += 1;
 338     buflen -= length;
 339     buffer += length;
 340
 341     result->gr_passwd=buffer;
 342
 343     if (!cpstr("x",&buffer,&buflen)) break;
 344
 345     if (buflen < sizeof(char*)) break;
 346     result->gr_mem=buffer;
 347     result->gr_mem[0] = NULL;
 348
 349     *errnop=errno;
 350     return NSS_STATUS_SUCCESS;
 351
 352   } while(0);
 353   *errnop=ENOENT;
 354   return NSS_STATUS_UNAVAIL;
 355 }
 356
 357 /**
 358  * A helper function to fill in the fields of "struct passwd"; used by
 359  * both _nss_afs_getpwuid_r() and _nss_afs_getpwnam_r().
 360  */
 361 enum nss_status fill_result_buf(uid_t uid,
 362                                 char* name,
 363                                 struct passwd *result_buf,
 364                                 char *buffer,
 365                                 size_t buflen,
 366                                 int *errnop) {
 367   result_buf->pw_name = name;
 368   do {
 369     /* set the password to "x" */
 370     result_buf->pw_passwd = buffer;
 371     if ( ! cpstr("x",&buffer, &buflen) ) break;
 372
 373     /* the uid and gid are both the uid passed in */
 374     result_buf->pw_uid = uid;
 375     result_buf->pw_gid = 65534;
 376
 377     /* make the gecos the same as the PTS name */
 378     result_buf->pw_gecos = buffer;
 379     if ( ! cpstr(result_buf->pw_name, &buffer, &buflen ) ) break;
 380
 381     // Set the homedirectory
 382     result_buf->pw_dir = buffer;
 383     if ( get_homedir(result_buf->pw_name,&buffer,&buflen) ) break;
 384
 385     // Set the login shell
 386     result_buf->pw_shell = buffer;
 387     if ( get_shell(result_buf->pw_name,&buffer,&buflen) ) break;
 388
 389     *errnop = errno;
 390     return NSS_STATUS_SUCCESS;
 391   } while(0);
 392
 393   *errnop = ERANGE;
 394   return NSS_STATUS_UNAVAIL;
 395 }
 396
 397
 398 /**
 399  * This function is exported; glibc will invoke it in order to gather
 400  * the user information (userid, homedir, shell) associated with a
 401  * numerical userid.
 402  */
 403 enum nss_status _nss_afs_getpwuid_r (uid_t uid,
 404                                      struct passwd *result_buf,
 405                                      char *buffer,
 406                                      size_t buflen,
 407                                      int *errnop) {
 408   int temp;
 409   char* name;
 410
 411   if (init_afs()) return NSS_STATUS_UNAVAIL;
 412
 413   name = buffer;
 414   temp = ptsid2name( uid, &buffer, &buflen);
 415   if (temp != NSS_STATUS_SUCCESS) {
 416     *errnop = ENOENT;
 417     return temp;
 418   }
 419
 420 #ifdef LIMIT_USERNAME_CHARS
 421   if ( strlen(result_buf->pw_name) > LIMIT_USERNAME_CHARS ) {
 422     result_buf->pw_name[LIMIT_USERNAME_CHARS] = '\0';
 423     buflen = buflen + ( buffer - &result_buf->pw_name[LIMIT_USERNAME_CHARS+1] );
 424     buffer = &result_buf->pw_name[LIMIT_USERNAME_CHARS+1];
 425   }
 426 #endif
 427
 428   return fill_result_buf(uid, name, result_buf, buffer, buflen, errnop);
 429 }
 430
 431 /**
 432  * This function is exported; glibc will invoke it in order to gather
 433  * the user information (userid, homedir, shell) associated with a
 434  * username.
 435  */
 436 enum nss_status _nss_afs_getpwnam_r (char *name,
 437                                      struct passwd *result_buf,
 438                                      char *buffer,
 439                                      size_t buflen,
 440                                      int *errnop) {
 441   uid_t uid;
 442   int temp;
 443
 444   if (init_afs()) return NSS_STATUS_UNAVAIL;
 445
 446   temp = ptsname2id(name,&uid);
 447   if (temp != NSS_STATUS_SUCCESS) {
 448     *errnop = ENOENT;
 449     return temp;
 450   }
 451
 452   return fill_result_buf(uid, name, result_buf, buffer, buflen, errnop);
 453 }
 454