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
  32 #include "udev.h"
  33 #include "udev_lib.h"
  34 #include "udev_version.h"
  35 #include "logging.h"
  36 #include "namedev.h"
  37 #include "udevdb.h"
  38
  39 static int delete_path(const char *path)
  40 {
  41         char *pos;
  42         int retval;
  43
  44         pos = strrchr(path, '/');
  45         while (1) {
  46                 *pos = '\0';
  47                 pos = strrchr(path, '/');
  48
  49                 /* don't remove the last one */
  50                 if ((pos == path) || (pos == NULL))
  51                         break;
  52
  53                 /* remove if empty */
  54                 retval = rmdir(path);
  55                 if (errno == ENOENT)
  56                         retval = 0;
  57                 if (retval) {
  58                         if (errno == ENOTEMPTY)
  59                                 return 0;
  60                         dbg("rmdir(%s) failed with error '%s'",
  61                             path, strerror(errno));
  62                         break;
  63                 }
  64                 dbg("removed '%s'", path);
  65         }
  66         return 0;
  67 }
  68
  69 /** Remove all permissions on the device node, before
  70   * unlinking it. This fixes a security issue.
  71   * If the user created a hard-link to the device node,
  72   * he can't use it any longer, because he lost permission
  73   * to do so.
  74   */
  75 static int secure_unlink(const char *filename)
  76 {
  77         int retval;
  78
  79         retval = chown(filename, 0, 0);
  80         if (retval) {
  81                 dbg("chown(%s, 0, 0) failed with error '%s'",
  82                     filename, strerror(errno));
  83                 /* We continue nevertheless.
  84                  * I think it's very unlikely for chown
  85                  * to fail here, if the file exists.
  86                  */
  87         }
  88         retval = chmod(filename, 0000);
  89         if (retval) {
  90                 dbg("chmod(%s, 0000) failed with error '%s'",
  91                     filename, strerror(errno));
  92                 /* We continue nevertheless. */
  93         }
  94         retval = unlink(filename);
  95         if (errno == ENOENT)
  96                 retval = 0;
  97         if (retval) {
  98                 dbg("unlink(%s) failed with error '%s'",
  99                         filename, strerror(errno));
 100         }
 101         return retval;
 102 }
 103
 104 static int delete_node(struct udevice *dev)
 105 {
 106         char filename[NAME_SIZE];
 107         char linkname[NAME_SIZE];
 108         char partitionname[NAME_SIZE];
 109         int retval;
 110         int i;
 111         char *pos;
 112         int len;
 113         int num;
 114
 115         strfieldcpy(filename, udev_root);
 116         strfieldcat(filename, dev->name);
 117
 118         info("removing device node '%s'", filename);
 119         retval = secure_unlink(filename);
 120         if (retval)
 121                 return retval;
 122
 123         /* remove all_partitions nodes */
 124         num = dev->partitions;
 125         if (num > 0) {
 126                 info("removing all_partitions '%s[1-%i]'", filename, num);
 127                 if (num > PARTITIONS_COUNT) {
 128                         info("garbage from udev database, skip all_partitions removal");
 129                         return -1;
 130                 }
 131                 for (i = 1; i <= num; i++) {
 132                         strfieldcpy(partitionname, filename);
 133                         strintcat(partitionname, i);
 134                         secure_unlink(partitionname);
 135                 }
 136         }
 137
 138         /* remove subdirectories */
 139         if (strchr(dev->name, '/'))
 140                 delete_path(filename);
 141
 142         foreach_strpart(dev->symlink, " ", pos, len) {
 143                 strfieldcpymax(linkname, pos, len+1);
 144                 strfieldcpy(filename, udev_root);
 145                 strfieldcat(filename, linkname);
 146
 147                 dbg("unlinking symlink '%s'", filename);
 148                 retval = unlink(filename);
 149                 if (errno == ENOENT)
 150                         retval = 0;
 151                 if (retval) {
 152                         dbg("unlink(%s) failed with error '%s'",
 153                                 filename, strerror(errno));
 154                         return retval;
 155                 }
 156                 if (strchr(dev->symlink, '/')) {
 157                         delete_path(filename);
 158                 }
 159         }
 160
 161         return retval;
 162 }
 163
 164 /*
 165  * look up the sysfs path in the database to get the node name to remove
 166  * If we can't find it, use kernel name for lack of anything else to know to do
 167  */
 168 int udev_remove_device(struct udevice *udev)
 169 {
 170         struct udevice db_dev;
 171         const char *temp;
 172         int retval;
 173
 174         if (udev->type != 'b' && udev->type != 'c')
 175                 return 0;
 176
 177         retval = udevdb_get_dev(udev->devpath, &db_dev);
 178         if (retval == 0) {
 179                 /* copy over the stored values to our device */
 180                 memcpy(udev, &db_dev, UDEVICE_DB_LEN);
 181         } else {
 182                 /* fall back to kernel name */
 183                 temp = strrchr(udev->devpath, '/');
 184                 if (temp == NULL)
 185                         return -ENODEV;
 186                 strfieldcpy(udev->name, &temp[1]);
 187                 dbg("'%s' not found in database, falling back on default name", udev->name);
 188         }
 189
 190         dbg("remove name='%s'", udev->name);
 191         udevdb_delete_dev(udev->devpath);
 192
 193         /* use full path to the environment */
 194         snprintf(udev->devname, NAME_SIZE-1, "%s%s", udev_root, udev->name);
 195
 196         return delete_node(udev);
 197 }