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 <stdio.h>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30
  31 #include "udev.h"
  32 #include "udev_lib.h"
  33 #include "udev_version.h"
  34 #include "logging.h"
  35 #include "namedev.h"
  36 #include "udevdb.h"
  37
  38 static int delete_path(char *path)
  39 {
  40         char *pos;
  41         int retval;
  42
  43         pos = strrchr(path, '/');
  44         while (1) {
  45                 *pos = '\0';
  46                 pos = strrchr(path, '/');
  47
  48                 /* don't remove the last one */
  49                 if ((pos == path) || (pos == NULL))
  50                         break;
  51
  52                 /* remove if empty */
  53                 retval = rmdir(path);
  54                 if (errno == ENOENT)
  55                         retval = 0;
  56                 if (retval) {
  57                         if (errno == ENOTEMPTY)
  58                                 return 0;
  59                         dbg("rmdir(%s) failed with error '%s'",
  60                             path, strerror(errno));
  61                         break;
  62                 }
  63                 dbg("removed '%s'", path);
  64         }
  65         return 0;
  66 }
  67
  68 /** Remove all permissions on the device node, before
  69   * unlinking it. This fixes a security issue.
  70   * If the user created a hard-link to the device node,
  71   * he can't use it any longer, because he lost permission
  72   * to do so.
  73   */
  74 static int secure_unlink(const char *filename)
  75 {
  76         int retval;
  77
  78         retval = chown(filename, 0, 0);
  79         if (retval) {
  80                 dbg("chown(%s, 0, 0) failed with error '%s'",
  81                     filename, strerror(errno));
  82                 /* We continue nevertheless.
  83                  * I think it's very unlikely for chown
  84                  * to fail here, if the file exists.
  85                  */
  86         }
  87         retval = chmod(filename, 0000);
  88         if (retval) {
  89                 dbg("chmod(%s, 0000) failed with error '%s'",
  90                     filename, strerror(errno));
  91                 /* We continue nevertheless. */
  92         }
  93         retval = unlink(filename);
  94         if (errno == ENOENT)
  95                 retval = 0;
  96         if (retval) {
  97                 dbg("unlink(%s) failed with error '%s'",
  98                         filename, strerror(errno));
  99         }
 100         return retval;
 101 }
 102
 103 static int delete_node(struct udevice *dev)
 104 {
 105         char filename[NAME_SIZE];
 106         char linkname[NAME_SIZE];
 107         char partitionname[NAME_SIZE];
 108         int retval;
 109         int i;
 110         char *pos;
 111         int len;
 112
 113         strfieldcpy(filename, udev_root);
 114         strfieldcat(filename, dev->name);
 115
 116         info("removing device node '%s'", filename);
 117         retval = secure_unlink(filename);
 118         if (retval)
 119                 return retval;
 120
 121         /* remove partition nodes */
 122         if (dev->partitions > 0) {
 123                 info("removing partitions '%s[1-%i]'", filename, dev->partitions);
 124                 for (i = 1; i <= dev->partitions; i++) {
 125                         strfieldcpy(partitionname, filename);
 126                         strintcat(partitionname, i);
 127                         secure_unlink(partitionname);
 128                 }
 129         }
 130
 131         /* remove subdirectories */
 132         if (strchr(dev->name, '/'))
 133                 delete_path(filename);
 134
 135         foreach_strpart(dev->symlink, " ", pos, len) {
 136                 strfieldcpymax(linkname, pos, len+1);
 137                 strfieldcpy(filename, udev_root);
 138                 strfieldcat(filename, linkname);
 139
 140                 dbg("unlinking symlink '%s'", filename);
 141                 retval = unlink(filename);
 142                 if (errno == ENOENT)
 143                         retval = 0;
 144                 if (retval) {
 145                         dbg("unlink(%s) failed with error '%s'",
 146                                 filename, strerror(errno));
 147                         return retval;
 148                 }
 149                 if (strchr(dev->symlink, '/')) {
 150                         delete_path(filename);
 151                 }
 152         }
 153
 154         return retval;
 155 }
 156
 157 /*
 158  * Look up the sysfs path in the database to see if we have named this device
 159  * something different from the kernel name.  If we have, us it.  If not, use
 160  * the default kernel name for lack of anything else to know to do.
 161  */
 162 int udev_remove_device(const char *path, const char *subsystem)
 163 {
 164         struct udevice dev;
 165         char *temp;
 166         int retval;
 167
 168         memset(&dev, 0x00, sizeof(dev));
 169
 170         retval = udevdb_get_dev(path, &dev);
 171         if (retval != 0) {
 172                 dbg("'%s' not found in database, falling back on default name", path);
 173                 temp = strrchr(path, '/');
 174                 if (temp == NULL)
 175                         return -ENODEV;
 176                 strfieldcpy(dev.name, &temp[1]);
 177         }
 178         dbg("name='%s'", dev.name);
 179
 180         dev.type = get_device_type(path, subsystem);
 181         dev_d_send(&dev, subsystem, path);
 182         udevdb_delete_dev(path);
 183
 184         if (dev.type == 'b' || dev.type == 'c')
 185                 retval = delete_node(&dev);
 186         else if (dev.type == 'n')
 187                 retval = 0;
 188
 189         return retval;
 190 }