conffile.c

   1 /* usmb - mount SMB shares via FUSE and Samba
   2  * Copyright (C) 2006-2010 Geoff Johnstone
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 3 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #include "config.h"
  18 #include <assert.h>
  19 #include <errno.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <fcntl.h>
  26 #include <pwd.h>
  27 #include <unistd.h>
  28 #include "utils.h"
  29 #include "xml.h"
  30 #include "conffile.h"
  31 #include "config.rng.h"
  32
  33
  34 static bool check_conf_perms (const char *conffile, int fd)
  35 {
  36   struct stat buf;
  37
  38   if (0 == fstat (fd, &buf))
  39   {
  40     if (getuid() != buf.st_uid)
  41     {
  42       fprintf (stderr, "You do not own the configuration file %s.\n", conffile);
  43       return false;
  44     }
  45
  46     if (buf.st_mode & (S_IRWXG | S_IRWXO))
  47     {
  48       fprintf (stderr, "Configuration file %s is accessible to non-owner.\n",
  49                conffile);
  50       return false;
  51     }
  52   }
  53
  54   else
  55   {
  56     fprintf (stderr, "Cannot stat configuration file %s: %s.\n",
  57              conffile, strerror (errno));
  58     return false;
  59   }
  60
  61   return true;
  62 }
  63
  64
  65 static bool conffile_read (const char *filename,
  66                            xmlDocPtr *doc,
  67                            xmlXPathContextPtr *ctx)
  68 {
  69   int fd = open (filename, O_RDONLY);
  70   if (-1 == fd)
  71   {
  72     fprintf (stderr, "Cannot open %s: %s.\n", filename, strerror (errno));
  73     return false;
  74   }
  75
  76   if (!check_conf_perms (filename, fd))
  77   {
  78     (void)close (fd);
  79     return false;
  80   }
  81
  82   *doc = xmlReadFd (fd, NULL, NULL, XML_PARSE_NONET);
  83   (void)close (fd);
  84
  85   if (NULL == *doc)
  86   {
  87     fprintf (stderr, "Cannot parse %s.\n", filename);
  88     return false;
  89   }
  90
  91   if (!xml_validate_relaxng (*doc, rng_config))
  92   {
  93     fprintf (stderr, "%s isn't a valid USMB configuration.\n", filename);
  94     xmlFreeDoc (*doc);
  95     return false;
  96   }
  97
  98   *ctx = xmlXPathNewContext (*doc);
  99   if (NULL == *ctx)
 100   {
 101     fputs ("Cannot create XPath context.\n", stderr);
 102     xmlFreeDoc (*doc);
 103     return false;
 104   }
 105
 106   return true;
 107 }
 108
 109
 110 static bool do_xpath_text (xmlXPathContextPtr ctx,
 111                            const char *parent, const char *id,
 112                            const char *child, char **out)
 113 {
 114   char xpath[2048];
 115
 116   if (!bsnprintf (xpath, sizeof (xpath),
 117                   "/usmbconfig/%s[@id='%s']/%s/text()", parent, id, child))
 118     return false;
 119
 120   return xml_xpath_text (ctx, xpath, (void *)out);
 121 }
 122
 123
 124 // Expand ~ in *mountpoint.
 125 static bool expand_tilde (char **mountpoint)
 126 {
 127   assert (NULL != mountpoint);
 128   assert (NULL != *mountpoint);
 129
 130   if ('~' != **mountpoint)
 131     return true;
 132
 133   // Extract the username.
 134   char * const username = (*mountpoint) + 1;
 135   char * const end = strchr (username, '/');
 136
 137   const char *dir = NULL;
 138
 139   if (('\0' == *username) || (end == username))  // No username => use HOME.
 140   {
 141     dir = getenv ("HOME");
 142   }
 143   else  // Else look up the user's home directory.
 144   {
 145     if (NULL != end)
 146       *end = '\0';
 147
 148     struct passwd * const pwd = getpwnam (username);
 149     if (NULL != pwd)
 150       dir = pwd->pw_dir;
 151
 152     if (NULL != end)
 153       *end = '/';
 154   }
 155
 156   if (NULL == dir)
 157   {
 158     fputs ("Failed to expand tilde in mount point.\n", stderr);
 159     return false;
 160   }
 161
 162   char *result;
 163   if (!baprintf (&result, "%s%s", dir, (NULL == end) ? "" : end))
 164   {
 165     perror ("Failed to expand tilde in mount point");
 166     return false;
 167   }
 168
 169   free (*mountpoint);
 170   *mountpoint = result;
 171   return true;
 172 }
 173
 174
 175 bool conffile_get_mount (const char *filename, const char *key,
 176                          char **server, char **share,
 177                          char **mountpoint, char **options,
 178                          char **domain, char **username,
 179                          char **password)
 180 {
 181   xmlDocPtr doc;
 182   xmlXPathContextPtr ctx;
 183   char xp[2048];
 184   char *creds = NULL;
 185
 186   *server = *share = *mountpoint = *options = NULL;
 187   *domain = *username = *password = NULL;
 188
 189   if (strchr (key, '\''))
 190   {
 191     fprintf (stderr, "Invalid share name: %s.\n", key);
 192     return false;
 193   }
 194
 195   if (!conffile_read (filename, &doc, &ctx))
 196     return false;
 197
 198   do {
 199     if (!do_xpath_text (ctx, "mount", key, "server", server)) break;
 200     if (!do_xpath_text (ctx, "mount", key, "share", share)) break;
 201     if (!do_xpath_text (ctx, "mount", key, "mountpoint", mountpoint)) break;
 202     if (!expand_tilde (mountpoint)) break;
 203     (void)do_xpath_text (ctx, "mount", key, "options", options);
 204
 205     if (!snprintf (xp, sizeof (xp), "/usmbconfig/mount[@id='%s']", key)) break;
 206     if (!xml_xpath_attr_value (ctx, xp, "credentials", &creds)) break;
 207
 208     (void)do_xpath_text (ctx, "credentials", creds, "domain", domain);
 209     if (!do_xpath_text (ctx, "credentials", creds, "username", username)) break;
 210
 211     if (!do_xpath_text (ctx, "credentials", creds, "password", password))
 212       *password = NULL;
 213
 214     xmlXPathFreeContext (ctx);
 215     xmlFreeDoc (doc);
 216
 217     return true;
 218     /*NOTREACHED*/
 219   } while (false /*CONSTCOND*/);
 220
 221   fputs ("Invalid configuration.\n", stderr);
 222
 223   xfree (*username);
 224   clear_and_free (*password);
 225   xfree (*domain);
 226   xfree (creds);
 227   xfree (*options);
 228   xfree (*mountpoint);
 229   xfree (*share);
 230   xfree (*server);
 231
 232   xmlXPathFreeContext (ctx);
 233   xmlFreeDoc (doc);
 234
 235   return false;
 236 }
 237