release/src/router/udev/udev_node.c

   1 /*
   2  * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   3  * Copyright (C) 2004-2006 Kay Sievers <kay.sievers@vrfy.org>
   4  *
   5  *      This program is free software; you can redistribute it and/or modify it
   6  *      under the terms of the GNU General Public License as published by the
   7  *      Free Software Foundation version 2 of the License.
   8  *
   9  *      This program is distributed in the hope that it will be useful, but
  10  *      WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *      General Public License for more details.
  13  *
  14  *      You should have received a copy of the GNU General Public License along
  15  *      with this program; if not, write to the Free Software Foundation, Inc.,
  16  *      51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  17  *
  18  */
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <stdio.h>
  23 #include <stddef.h>
  24 #include <fcntl.h>
  25 #include <unistd.h>
  26 #include <errno.h>
  27 #include <grp.h>
  28 #include <dirent.h>
  29 #include <sys/stat.h>
  30 #include <sys/types.h>
  31
  32 #include "udev.h"
  33 #include "udev_rules.h"
  34 #include "udev_selinux.h"
  35
  36 #define TMP_FILE_EXT            ".udev-tmp"
  37
  38 int udev_node_mknod(struct udevice *udev, const char *file, dev_t devt, mode_t mode, uid_t uid, gid_t gid)
  39 {
  40         char file_tmp[PATH_SIZE + sizeof(TMP_FILE_EXT)];
  41         struct stat stats;
  42         int retval = 0;
  43
  44         if (major(devt) != 0 && strcmp(udev->dev->subsystem, "block") == 0)
  45                 mode |= S_IFBLK;
  46         else
  47                 mode |= S_IFCHR;
  48
  49         if (lstat(file, &stats) == 0) {
  50                 if ((stats.st_mode & S_IFMT) == (mode & S_IFMT) && (stats.st_rdev == devt)) {
  51                         info("preserve file '%s', because it has correct dev_t", file);
  52                         selinux_setfilecon(file, udev->dev->kernel, stats.st_mode);
  53                         goto perms;
  54                 }
  55         } else {
  56                 selinux_setfscreatecon(file, udev->dev->kernel, mode);
  57                 retval = mknod(file, mode, devt);
  58                 selinux_resetfscreatecon();
  59                 if (retval == 0)
  60                         goto perms;
  61         }
  62
  63         info("atomically replace '%s'", file);
  64         strlcpy(file_tmp, file, sizeof(file_tmp));
  65         strlcat(file_tmp, TMP_FILE_EXT, sizeof(file_tmp));
  66         selinux_setfscreatecon(file_tmp, udev->dev->kernel, mode);
  67         retval = mknod(file_tmp, mode, devt);
  68         selinux_resetfscreatecon();
  69         if (retval != 0) {
  70                 err("mknod(%s, %#o, %u, %u) failed: %s",
  71                     file_tmp, mode, major(devt), minor(devt), strerror(errno));
  72                 goto exit;
  73         }
  74         retval = rename(file_tmp, file);
  75         if (retval != 0) {
  76                 err("rename(%s, %s) failed: %s",
  77                     file_tmp, file, strerror(errno));
  78                 unlink(file_tmp);
  79                 goto exit;
  80         }
  81
  82 perms:
  83         dbg("chmod(%s, %#o)", file, mode);
  84         if (chmod(file, mode) != 0) {
  85                 err("chmod(%s, %#o) failed: %s", file, mode, strerror(errno));
  86                 goto exit;
  87         }
  88
  89         if (uid != 0 || gid != 0) {
  90                 dbg("chown(%s, %u, %u)", file, uid, gid);
  91                 if (chown(file, uid, gid) != 0) {
  92                         err("chown(%s, %u, %u) failed: %s",
  93                             file, uid, gid, strerror(errno));
  94                         goto exit;
  95                 }
  96         }
  97 exit:
  98         return retval;
  99 }
 100
 101 static int node_symlink(const char *node, const char *slink)
 102 {
 103         struct stat stats;
 104         char target[PATH_SIZE] = "";
 105         char slink_tmp[PATH_SIZE + sizeof(TMP_FILE_EXT)];
 106         int i = 0;
 107         int tail = 0;
 108         int len;
 109         int retval = 0;
 110
 111         /* use relative link */
 112         while (node[i] && (node[i] == slink[i])) {
 113                 if (node[i] == '/')
 114                         tail = i+1;
 115                 i++;
 116         }
 117         while (slink[i] != '\0') {
 118                 if (slink[i] == '/')
 119                         strlcat(target, "../", sizeof(target));
 120                 i++;
 121         }
 122         strlcat(target, &node[tail], sizeof(target));
 123
 124         /* preserve link with correct target, do not replace node of other device */
 125         if (lstat(slink, &stats) == 0) {
 126                 if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode)) {
 127                         struct stat stats2;
 128
 129                         info("found existing node instead of symlink '%s'", slink);
 130                         if (lstat(node, &stats2) == 0) {
 131                                 if ((stats.st_mode & S_IFMT) == (stats2.st_mode & S_IFMT) &&
 132                                     stats.st_rdev == stats2.st_rdev) {
 133                                         info("replace device node '%s' with symlink to our node '%s'", slink, node);
 134                                 } else {
 135                                         err("device node '%s' already exists, link '%s' will not overwrite it", node, slink);
 136                                         goto exit;
 137                                 }
 138                         }
 139                 } else if (S_ISLNK(stats.st_mode)) {
 140                         char buf[PATH_SIZE];
 141
 142                         info("found existing symlink '%s'", slink);
 143                         len = readlink(slink, buf, sizeof(buf));
 144                         if (len > 0) {
 145                                 buf[len] = '\0';
 146                                 if (strcmp(target, buf) == 0) {
 147                                         info("preserve already existing symlink '%s' to '%s'", slink, target);
 148                                         selinux_setfilecon(slink, NULL, S_IFLNK);
 149                                         goto exit;
 150                                 }
 151                         }
 152                 }
 153         } else {
 154                 info("creating symlink '%s' to '%s'", slink, target);
 155                 selinux_setfscreatecon(slink, NULL, S_IFLNK);
 156                 retval = symlink(target, slink);
 157                 selinux_resetfscreatecon();
 158                 if (retval == 0)
 159                         goto exit;
 160         }
 161
 162         info("atomically replace '%s'", slink);
 163         strlcpy(slink_tmp, slink, sizeof(slink_tmp));
 164         strlcat(slink_tmp, TMP_FILE_EXT, sizeof(slink_tmp));
 165         selinux_setfscreatecon(slink_tmp, NULL, S_IFLNK);
 166         retval = symlink(target, slink_tmp);
 167         selinux_resetfscreatecon();
 168         if (retval != 0) {
 169                 err("symlink(%s, %s) failed: %s", target, slink_tmp, strerror(errno));
 170                 goto exit;
 171         }
 172         retval = rename(slink_tmp, slink);
 173         if (retval != 0) {
 174                 err("rename(%s, %s) failed: %s", slink_tmp, slink, strerror(errno));
 175                 unlink(slink_tmp);
 176                 goto exit;
 177         }
 178 exit:
 179         return retval;
 180 }
 181
 182 static int update_link(struct udevice *udev, const char *name)
 183 {
 184         LIST_HEAD(name_list);
 185         char slink[PATH_SIZE];
 186         char node[PATH_SIZE];
 187         struct udevice *udev_db;
 188         struct name_entry *device;
 189         char target[PATH_MAX] = "";
 190         int count;
 191         int priority = 0;
 192         int rc = 0;
 193
 194         strlcpy(slink, udev_root, sizeof(slink));
 195         strlcat(slink, "/", sizeof(slink));
 196         strlcat(slink, name, sizeof(slink));
 197
 198         count = udev_db_get_devices_by_name(name, &name_list);
 199         info("found %i devices with name '%s'", count, name);
 200
 201         /* if we don't have a reference, delete it */
 202         if (count <= 0) {
 203                 info("no reference left, remove '%s'", name);
 204                 if (!udev->test_run) {
 205                         unlink(slink);
 206                         delete_path(slink);
 207                 }
 208                 goto out;
 209         }
 210
 211         /* find the device with the highest priority */
 212         list_for_each_entry(device, &name_list, node) {
 213                 info("found '%s' for '%s'", device->name, name);
 214
 215                 /* did we find ourself? we win, if we have the same priority */
 216                 if (strcmp(udev->dev->devpath, device->name) == 0) {
 217                         info("compare (our own) priority of '%s' %i >= %i",
 218                              udev->dev->devpath, udev->link_priority, priority);
 219                         if (target[0] == '\0' || udev->link_priority >= priority) {
 220                                 priority = udev->link_priority;
 221                                 strlcpy(target, udev->name, sizeof(target));
 222                         }
 223                         continue;
 224                 }
 225
 226                 /* or something else, then read priority from database */
 227                 udev_db = udev_device_init(NULL);
 228                 if (udev_db == NULL)
 229                         continue;
 230                 if (udev_db_get_device(udev_db, device->name) == 0) {
 231                         info("compare priority of '%s' %i > %i",
 232                              udev_db->dev->devpath, udev_db->link_priority, priority);
 233                         if (target[0] == '\0' || udev_db->link_priority > priority) {
 234                                 priority = udev_db->link_priority;
 235                                 strlcpy(target, udev_db->name, sizeof(target));
 236                         }
 237                 }
 238                 udev_device_cleanup(udev_db);
 239         }
 240         name_list_cleanup(&name_list);
 241
 242         if (target[0] == '\0') {
 243                 err("missing target for '%s'", name);
 244                 rc = -1;
 245                 goto out;
 246         }
 247
 248         /* create symlink to the target with the highest priority */
 249         strlcpy(node, udev_root, sizeof(node));
 250         strlcat(node, "/", sizeof(node));
 251         strlcat(node, target, sizeof(node));
 252         info("'%s' with target '%s' has the highest priority %i, create it", name, target, priority);
 253         if (!udev->test_run) {
 254                 create_path(slink);
 255                 node_symlink(node, slink);
 256         }
 257 out:
 258         return rc;
 259 }
 260
 261 void udev_node_update_symlinks(struct udevice *udev, struct udevice *udev_old)
 262 {
 263         struct name_entry *name_loop;
 264         char symlinks[PATH_SIZE] = "";
 265
 266         list_for_each_entry(name_loop, &udev->symlink_list, node) {
 267                 info("update symlink '%s' of '%s'", name_loop->name, udev->dev->devpath);
 268                 update_link(udev, name_loop->name);
 269                 strlcat(symlinks, udev_root, sizeof(symlinks));
 270                 strlcat(symlinks, "/", sizeof(symlinks));
 271                 strlcat(symlinks, name_loop->name, sizeof(symlinks));
 272                 strlcat(symlinks, " ", sizeof(symlinks));
 273         }
 274
 275         /* export symlinks to environment */
 276         remove_trailing_chars(symlinks, ' ');
 277         if (symlinks[0] != '\0')
 278                 setenv("DEVLINKS", symlinks, 1);
 279
 280         /* update possible left-over symlinks (device metadata changed) */
 281         if (udev_old != NULL) {
 282                 struct name_entry *link_loop;
 283                 struct name_entry *link_old_loop;
 284                 int found;
 285
 286                 /* remove current symlinks from old list */
 287                 list_for_each_entry(link_old_loop, &udev_old->symlink_list, node) {
 288                         found = 0;
 289                         list_for_each_entry(link_loop, &udev->symlink_list, node) {
 290                                 if (strcmp(link_old_loop->name, link_loop->name) == 0) {
 291                                         found = 1;
 292                                         break;
 293                                 }
 294                         }
 295                         if (!found) {
 296                                 /* link does no longer belong to this device */
 297                                 info("update old symlink '%s' no longer belonging to '%s'",
 298                                      link_old_loop->name, udev->dev->devpath);
 299                                 update_link(udev, link_old_loop->name);
 300                         }
 301                 }
 302
 303                 /*
 304                  * if the node name has changed, delete the node,
 305                  * or possibly restore a symlink of another device
 306                  */
 307                 if (strcmp(udev->name, udev_old->name) != 0)
 308                         update_link(udev, udev_old->name);
 309         }
 310 }
 311
 312 int udev_node_add(struct udevice *udev)
 313 {
 314         char filename[PATH_SIZE];
 315         uid_t uid;
 316         gid_t gid;
 317         int i;
 318         int retval = 0;
 319
 320         strlcpy(filename, udev_root, sizeof(filename));
 321         strlcat(filename, "/", sizeof(filename));
 322         strlcat(filename, udev->name, sizeof(filename));
 323         create_path(filename);
 324
 325         if (strcmp(udev->owner, "root") == 0)
 326                 uid = 0;
 327         else {
 328                 char *endptr;
 329                 unsigned long id;
 330
 331                 id = strtoul(udev->owner, &endptr, 10);
 332                 if (endptr[0] == '\0')
 333                         uid = (uid_t) id;
 334                 else
 335                         uid = lookup_user(udev->owner);
 336         }
 337
 338         if (strcmp(udev->group, "root") == 0)
 339                 gid = 0;
 340         else {
 341                 char *endptr;
 342                 unsigned long id;
 343
 344                 id = strtoul(udev->group, &endptr, 10);
 345                 if (endptr[0] == '\0')
 346                         gid = (gid_t) id;
 347                 else
 348                         gid = lookup_group(udev->group);
 349         }
 350
 351         info("creating device node '%s', major=%d, minor=%d, mode=%#o, uid=%d, gid=%d",
 352              filename, major(udev->devt), minor(udev->devt), udev->mode, uid, gid);
 353
 354         if (!udev->test_run)
 355                 if (udev_node_mknod(udev, filename, udev->devt, udev->mode, uid, gid) != 0) {
 356                         retval = -1;
 357                         goto exit;
 358                 }
 359
 360         setenv("DEVNAME", filename, 1);
 361
 362         /* create all_partitions if requested */
 363         if (udev->partitions) {
 364                 char partitionname[PATH_SIZE];
 365                 char *attr;
 366                 int range;
 367
 368                 /* take the maximum registered minor range */
 369                 attr = sysfs_attr_get_value(udev->dev->devpath, "range");
 370                 if (attr != NULL) {
 371                         range = atoi(attr);
 372                         if (range > 1)
 373                                 udev->partitions = range-1;
 374                 }
 375                 info("creating device partition nodes '%s[1-%i]'", filename, udev->partitions);
 376                 if (!udev->test_run) {
 377                         for (i = 1; i <= udev->partitions; i++) {
 378                                 dev_t part_devt;
 379
 380                                 snprintf(partitionname, sizeof(partitionname), "%s%d", filename, i);
 381                                 partitionname[sizeof(partitionname)-1] = '\0';
 382                                 part_devt = makedev(major(udev->devt), minor(udev->devt) + i);
 383                                 udev_node_mknod(udev, partitionname, part_devt, udev->mode, uid, gid);
 384                         }
 385                 }
 386         }
 387 exit:
 388         return retval;
 389 }
 390
 391 int udev_node_remove(struct udevice *udev)
 392 {
 393         char filename[PATH_SIZE];
 394         char partitionname[PATH_SIZE];
 395         struct stat stats;
 396         int retval = 0;
 397         int num;
 398
 399         strlcpy(filename, udev_root, sizeof(filename));
 400         strlcat(filename, "/", sizeof(filename));
 401         strlcat(filename, udev->name, sizeof(filename));
 402         if (stat(filename, &stats) != 0) {
 403                 dbg("device node '%s' not found", filename);
 404                 return -1;
 405         }
 406         if (udev->devt && stats.st_rdev != udev->devt) {
 407                 info("device node '%s' points to a different device, skip removal", filename);
 408                 return -1;
 409         }
 410
 411         info("removing device node '%s'", filename);
 412         if (!udev->test_run)
 413                 retval = unlink_secure(filename);
 414         if (retval)
 415                 return retval;
 416
 417         setenv("DEVNAME", filename, 1);
 418         num = udev->partitions;
 419         if (num > 0) {
 420                 int i;
 421
 422                 info("removing all_partitions '%s[1-%i]'", filename, num);
 423                 if (num > 255)
 424                         return -1;
 425                 for (i = 1; i <= num; i++) {
 426                         snprintf(partitionname, sizeof(partitionname), "%s%d", filename, i);
 427                         partitionname[sizeof(partitionname)-1] = '\0';
 428                         if (!udev->test_run)
 429                                 unlink_secure(partitionname);
 430                 }
 431         }
 432         delete_path(filename);
 433         return retval;
 434 }