udev_remove.c

   1 /*
   2  * udev-remove.c
   3  *
   4  * Userspace devfs
   5  *
   6  * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   7  *
   8  *
   9  *      This program is free software; you can redistribute it and/or modify it
  10  *      under the terms of the GNU General Public License as published by the
  11  *      Free Software Foundation version 2 of the License.
  12  *
  13  *      This program is distributed in the hope that it will be useful, but
  14  *      WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  *      General Public License for more details.
  17  *
  18  *      You should have received a copy of the GNU General Public License along
  19  *      with this program; if not, write to the Free Software Foundation, Inc.,
  20  *      675 Mass Ave, Cambridge, MA 02139, USA.
  21  *
  22  */
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <stddef.h>
  27 #include <stdio.h>
  28 #include <fcntl.h>
  29 #include <unistd.h>
  30 #include <errno.h>
  31 #include <sys/stat.h>
  32
  33 #include "udev.h"
  34 #include "udev_lib.h"
  35 #include "udev_version.h"
  36 #include "logging.h"
  37 #include "namedev.h"
  38 #include "udevdb.h"
  39
  40 static int delete_path(const char *path)
  41 {
  42         char *pos;
  43         int retval;
  44
  45         pos = strrchr(path, '/');
  46         while (1) {
  47                 *pos = '\0';
  48                 pos = strrchr(path, '/');
  49
  50                 /* don't remove the last one */
  51                 if ((pos == path) || (pos == NULL))
  52                         break;
  53
  54                 /* remove if empty */
  55                 retval = rmdir(path);
  56                 if (errno == ENOENT)
  57                         retval = 0;
  58                 if (retval) {
  59                         if (errno == ENOTEMPTY)
  60                                 return 0;
  61                         dbg("rmdir(%s) failed with error '%s'",
  62                             path, strerror(errno));
  63                         break;
  64                 }
  65                 dbg("removed '%s'", path);
  66         }
  67         return 0;
  68 }
  69
  70 /** Remove all permissions on the device node, before
  71   * unlinking it. This fixes a security issue.
  72   * If the user created a hard-link to the device node,
  73   * he can't use it any longer, because he lost permission
  74   * to do so.
  75   */
  76 static int secure_unlink(const char *filename)
  77 {
  78         int retval;
  79
  80         retval = chown(filename, 0, 0);
  81         if (retval) {
  82                 dbg("chown(%s, 0, 0) failed with error '%s'",
  83                     filename, strerror(errno));
  84                 /* We continue nevertheless.
  85                  * I think it's very unlikely for chown
  86                  * to fail here, if the file exists.
  87                  */
  88         }
  89         retval = chmod(filename, 0000);
  90         if (retval) {
  91                 dbg("chmod(%s, 0000) failed with error '%s'",
  92                     filename, strerror(errno));
  93                 /* We continue nevertheless. */
  94         }
  95         retval = unlink(filename);
  96         if (errno == ENOENT)
  97                 retval = 0;
  98         if (retval) {
  99                 dbg("unlink(%s) failed with error '%s'",
 100                         filename, strerror(errno));
 101         }
 102         return retval;
 103 }
 104
 105 static int delete_node(struct udevice *dev)
 106 {
 107         char filename[NAME_SIZE];
 108         char linkname[NAME_SIZE];
 109         char partitionname[NAME_SIZE];
 110         int retval;
 111         int i;
 112         char *pos;
 113         int len;
 114         int num;
 115
 116         strfieldcpy(filename, udev_root);
 117         strfieldcat(filename, dev->name);
 118
 119         info("removing device node '%s'", filename);
 120         retval = secure_unlink(filename);
 121         if (retval)
 122                 return retval;
 123
 124         /* remove all_partitions nodes */
 125         num = dev->partitions;
 126         if (num > 0) {
 127                 info("removing all_partitions '%s[1-%i]'", filename, num);
 128                 if (num > PARTITIONS_COUNT) {
 129                         info("garbage from udev database, skip all_partitions removal");
 130                         return -1;
 131                 }
 132                 for (i = 1; i <= num; i++) {
 133                         strfieldcpy(partitionname, filename);
 134                         strintcat(partitionname, i);
 135                         secure_unlink(partitionname);
 136                 }
 137         }
 138
 139         /* remove subdirectories */
 140         if (strchr(dev->name, '/'))
 141                 delete_path(filename);
 142
 143         foreach_strpart(dev->symlink, " ", pos, len) {
 144                 strfieldcpymax(linkname, pos, len+1);
 145                 strfieldcpy(filename, udev_root);
 146                 strfieldcat(filename, linkname);
 147
 148                 dbg("unlinking symlink '%s'", filename);
 149                 retval = unlink(filename);
 150                 if (errno == ENOENT)
 151                         retval = 0;
 152                 if (retval) {
 153                         dbg("unlink(%s) failed with error '%s'",
 154                                 filename, strerror(errno));
 155                         return retval;
 156                 }
 157                 if (strchr(dev->symlink, '/')) {
 158                         delete_path(filename);
 159                 }
 160         }
 161
 162         return retval;
 163 }
 164
 165 /*
 166  * look up the sysfs path in the database to get the node name to remove
 167  * If we can't find it, use kernel name for lack of anything else to know to do
 168  */
 169 int udev_remove_device(struct udevice *udev)
 170 {
 171         struct udevice db_dev;
 172         const char *temp;
 173         int retval;
 174
 175         if (udev->type != 'b' && udev->type != 'c')
 176                 return 0;
 177
 178         retval = udevdb_get_dev(udev->devpath, &db_dev);
 179         if (retval == 0) {
 180                 /* copy over the stored values to our device */
 181                 memcpy(udev, &db_dev, UDEVICE_DB_LEN);
 182         } else {
 183                 /* fall back to kernel name */
 184                 temp = strrchr(udev->devpath, '/');
 185                 if (temp == NULL)
 186                         return -ENODEV;
 187                 strfieldcpy(udev->name, &temp[1]);
 188                 dbg("'%s' not found in database, falling back on default name", udev->name);
 189         }
 190
 191         dbg("remove name='%s'", udev->name);
 192         udevdb_delete_dev(udev->devpath);
 193
 194         /* use full path to the environment */
 195         snprintf(udev->devname, NAME_SIZE-1, "%s%s", udev_root, udev->name);
 196
 197         return delete_node(udev);
 198 }