/* * Copyright (C) 2003-2010 Kay Sievers <kay.sievers@vrfy.org> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <stdlib.h> #include <string.h> #include <stdio.h> #include <stddef.h> #include <stdbool.h> #include <fcntl.h> #include <unistd.h> #include <errno.h> #include <grp.h> #include <dirent.h> #include <sys/time.h> #include <sys/stat.h> #include <sys/types.h> #include "udev.h" #define TMP_FILE_EXT ".udev-tmp" int udev_node_mknod(struct udev_device *dev, const char *file, mode_t mode, uid_t uid, gid_t gid) { struct udev *udev = udev_device_get_udev(dev); dev_t devnum = udev_device_get_devnum(dev); struct stat stats; int err = 0; if (strcmp(udev_device_get_subsystem(dev), "block") == 0) mode |= S_IFBLK; else mode |= S_IFCHR; if (file == NULL) file = udev_device_get_devnode(dev); if (lstat(file, &stats) == 0) { if (((stats.st_mode & S_IFMT) == (mode & S_IFMT)) && (stats.st_rdev == devnum)) { info(udev, "preserve file '%s', because it has correct dev_t\n", file); if ((stats.st_mode & 0777) != (mode & 0777) || stats.st_uid != uid || stats.st_gid != gid) { /* preserve 'sticky' bit, if already set */ mode |= stats.st_mode & 01000; info(udev, "set permissions %s, %#o, uid=%u, gid=%u\n", file, mode, uid, gid); chmod(file, mode); chown(file, uid, gid); } else { info(udev, "preserve permissions %s, %#o, uid=%u, gid=%u\n", file, mode, uid, gid); } /* * Set initial selinux file context only on add events. * We set the proper context on bootup (triger) or for newly * added devices, but we don't change it later, in case * something else has set a custom context in the meantime. */ if (strcmp(udev_device_get_action(dev), "add") == 0) udev_selinux_lsetfilecon(udev, file, mode); /* always update timestamp when we re-use the node, like on media change events */ utimensat(AT_FDCWD, file, NULL, 0); } else { char file_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)]; info(udev, "atomically replace existing file '%s'\n", file); util_strscpyl(file_tmp, sizeof(file_tmp), file, TMP_FILE_EXT, NULL); unlink(file_tmp); udev_selinux_setfscreatecon(udev, file_tmp, mode); err = mknod(file_tmp, mode, devnum); udev_selinux_resetfscreatecon(udev); if (err != 0) { err(udev, "mknod '%s' %u:%u %#o failed: %m\n", file_tmp, major(devnum), minor(devnum), mode); goto exit; } err = rename(file_tmp, file); if (err != 0) { err(udev, "rename '%s' '%s' failed: %m\n", file_tmp, file); unlink(file_tmp); goto exit; } info(udev, "set permissions '%s' %#o uid=%u gid=%u\n", file, mode, uid, gid); chmod(file, mode); chown(file, uid, gid); } } else { info(udev, "mknod '%s' %u:%u %#o\n", file, major(devnum), minor(devnum), mode); do { err = util_create_path_selinux(udev, file); if (err != 0 && err != -ENOENT) break; udev_selinux_setfscreatecon(udev, file, mode); err = mknod(file, mode, devnum); if (err != 0) err = -errno; udev_selinux_resetfscreatecon(udev); } while (err == -ENOENT); if (err != 0 && err != -EEXIST) err(udev, "mknod '%s' %u:%u %#o' failed: %m\n", file, major(devnum), minor(devnum), mode); info(udev, "set permissions '%s' %#o uid=%u gid=%u\n", file, mode, uid, gid); chmod(file, mode); chown(file, uid, gid); } exit: return err; } static int node_symlink(struct udev *udev, const char *node, const char *slink) { struct stat stats; char target[UTIL_PATH_SIZE]; char *s; size_t l; char slink_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)]; int i = 0; int tail = 0; int err = 0; /* use relative link */ target[0] = '\0'; while (node[i] && (node[i] == slink[i])) { if (node[i] == '/') tail = i+1; i++; } s = target; l = sizeof(target); while (slink[i] != '\0') { if (slink[i] == '/') l = util_strpcpy(&s, l, "../"); i++; } l = util_strscpy(s, l, &node[tail]); if (l == 0) { err = -EINVAL; goto exit; } /* preserve link with correct target, do not replace node of other device */ if (lstat(slink, &stats) == 0) { if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode)) { struct stat stats2; info(udev, "found existing node instead of symlink '%s'\n", slink); if (lstat(node, &stats2) == 0) { if ((stats.st_mode & S_IFMT) == (stats2.st_mode & S_IFMT) && stats.st_rdev == stats2.st_rdev && stats.st_ino != stats2.st_ino) { info(udev, "replace device node '%s' with symlink to our node '%s'\n", slink, node); } else { err(udev, "device node '%s' already exists, " "link to '%s' will not overwrite it\n", slink, node); goto exit; } } } else if (S_ISLNK(stats.st_mode)) { char buf[UTIL_PATH_SIZE]; int len; dbg(udev, "found existing symlink '%s'\n", slink); len = readlink(slink, buf, sizeof(buf)); if (len > 0 && len < (int)sizeof(buf)) { buf[len] = '\0'; if (strcmp(target, buf) == 0) { info(udev, "preserve already existing symlink '%s' to '%s'\n", slink, target); udev_selinux_lsetfilecon(udev, slink, S_IFLNK); utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW); goto exit; } } } } else { info(udev, "creating symlink '%s' to '%s'\n", slink, target); do { err = util_create_path_selinux(udev, slink); if (err != 0 && err != -ENOENT) break; udev_selinux_setfscreatecon(udev, slink, S_IFLNK); err = symlink(target, slink); if (err != 0) err = -errno; udev_selinux_resetfscreatecon(udev); } while (err == -ENOENT); if (err == 0) goto exit; } info(udev, "atomically replace '%s'\n", slink); util_strscpyl(slink_tmp, sizeof(slink_tmp), slink, TMP_FILE_EXT, NULL); unlink(slink_tmp); do { err = util_create_path_selinux(udev, slink_tmp); if (err != 0 && err != -ENOENT) break; udev_selinux_setfscreatecon(udev, slink_tmp, S_IFLNK); err = symlink(target, slink_tmp); if (err != 0) err = -errno; udev_selinux_resetfscreatecon(udev); } while (err == -ENOENT); if (err != 0) { err(udev, "symlink '%s' '%s' failed: %m\n", target, slink_tmp); goto exit; } err = rename(slink_tmp, slink); if (err != 0) { err(udev, "rename '%s' '%s' failed: %m\n", slink_tmp, slink); unlink(slink_tmp); } exit: return err; } /* find device node of device with highest priority */ static const char *link_find_prioritized(struct udev_device *dev, bool add, const char *stackdir, char *buf, size_t bufsize) { struct udev *udev = udev_device_get_udev(dev); DIR *dir; int priority = 0; const char *target = NULL; if (add) { priority = udev_device_get_devlink_priority(dev); util_strscpy(buf, bufsize, udev_device_get_devnode(dev)); target = buf; } dir = opendir(stackdir); if (dir == NULL) return target; for (;;) { struct udev_device *dev_db; struct dirent *dent; dent = readdir(dir); if (dent == NULL || dent->d_name[0] == '\0') break; if (dent->d_name[0] == '.') continue; info(udev, "found '%s' claiming '%s'\n", dent->d_name, stackdir); /* did we find ourself? */ if (strcmp(dent->d_name, udev_device_get_id_filename(dev)) == 0) continue; dev_db = udev_device_new_from_id_filename(udev, dent->d_name); if (dev_db != NULL) { const char *devnode; devnode = udev_device_get_devnode(dev_db); if (devnode != NULL) { dbg(udev, "compare priority of '%s'(%i) > '%s'(%i)\n", target, priority, udev_device_get_devnode(dev_db), udev_device_get_devlink_priority(dev_db)); if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) { info(udev, "'%s' claims priority %i for '%s'\n", udev_device_get_syspath(dev_db), udev_device_get_devlink_priority(dev_db), stackdir); priority = udev_device_get_devlink_priority(dev_db); util_strscpy(buf, bufsize, devnode); target = buf; } } udev_device_unref(dev_db); } } closedir(dir); return target; } /* manage "stack of names" with possibly specified device priorities */ static void link_update(struct udev_device *dev, const char *slink, bool add) { struct udev *udev = udev_device_get_udev(dev); char name_enc[UTIL_PATH_SIZE]; char filename[UTIL_PATH_SIZE * 2]; char dirname[UTIL_PATH_SIZE]; const char *target; char buf[UTIL_PATH_SIZE]; dbg(udev, "update symlink '%s' of '%s'\n", slink, udev_device_get_syspath(dev)); util_path_encode(&slink[strlen(udev_get_dev_path(udev))+1], name_enc, sizeof(name_enc)); util_strscpyl(dirname, sizeof(dirname), udev_get_run_path(udev), "/links/", name_enc, NULL); util_strscpyl(filename, sizeof(filename), dirname, "/", udev_device_get_id_filename(dev), NULL); if (!add) { dbg(udev, "removing index: '%s'\n", filename); if (unlink(filename) == 0) rmdir(dirname); } target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf)); if (target == NULL) { info(udev, "no reference left, remove '%s'\n", slink); if (unlink(slink) == 0) util_delete_path(udev, slink); } else { info(udev, "creating link '%s' to '%s'\n", slink, target); node_symlink(udev, target, slink); } if (add) { int err; dbg(udev, "creating index: '%s'\n", filename); do { int fd; err = util_create_path(udev, filename); if (err != 0 && err != -ENOENT) break; fd = open(filename, O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444); if (fd >= 0) close(fd); else err = -errno; } while (err == -ENOENT); } } void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev_old) { struct udev *udev = udev_device_get_udev(dev); struct udev_list_entry *list_entry; /* update possible left-over symlinks */ udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev_old)) { const char *name = udev_list_entry_get_name(list_entry); struct udev_list_entry *list_entry_current; int found; /* check if old link name still belongs to this device */ found = 0; udev_list_entry_foreach(list_entry_current, udev_device_get_devlinks_list_entry(dev)) { const char *name_current = udev_list_entry_get_name(list_entry_current); if (strcmp(name, name_current) == 0) { found = 1; break; } } if (found) continue; info(udev, "update old name, '%s' no longer belonging to '%s'\n", name, udev_device_get_devpath(dev)); link_update(dev, name, 0); } } int udev_node_add(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid) { struct udev *udev = udev_device_get_udev(dev); char filename[UTIL_PATH_SIZE]; struct udev_list_entry *list_entry; int err = 0; info(udev, "creating device node '%s', devnum=%d:%d, mode=%#o, uid=%d, gid=%d\n", udev_device_get_devnode(dev), major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)), mode, uid, gid); if (udev_node_mknod(dev, NULL, mode, uid, gid) != 0) { err = -1; goto exit; } /* always add /dev/{block,char}/$major:$minor */ snprintf(filename, sizeof(filename), "%s/%s/%u:%u", udev_get_dev_path(udev), strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char", major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev))); node_symlink(udev, udev_device_get_devnode(dev), filename); /* create/update symlinks, add symlinks to name index */ udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) { if (udev_list_entry_get_num(list_entry)) /* simple unmanaged link name */ node_symlink(udev, udev_device_get_devnode(dev), udev_list_entry_get_name(list_entry)); else link_update(dev, udev_list_entry_get_name(list_entry), 1); } exit: return err; } int udev_node_remove(struct udev_device *dev) { struct udev *udev = udev_device_get_udev(dev); struct udev_list_entry *list_entry; const char *devnode; struct stat stats; struct udev_device *dev_check; char filename[UTIL_PATH_SIZE]; int err = 0; /* remove/update symlinks, remove symlinks from name index */ udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) link_update(dev, udev_list_entry_get_name(list_entry), 0); devnode = udev_device_get_devnode(dev); if (devnode == NULL) goto out; if (stat(devnode, &stats) == 0) { if (stats.st_rdev != udev_device_get_devnum(dev)) { info(udev, "device node '%s' points to a different device, skip removal\n", devnode); err = -1; goto out; } if (stats.st_mode & 01000) { info(udev, "device node '%s' has sticky bit set, skip removal\n", devnode); goto out; } } else { info(udev, "device node '%s' not found\n", devnode); } dev_check = udev_device_new_from_syspath(udev, udev_device_get_syspath(dev)); if (dev_check != NULL) { /* do not remove device node if the same sys-device is re-created in the meantime */ info(udev, "keeping device node of existing device'%s'\n", devnode); udev_device_unref(dev_check); goto out; } info(udev, "removing device node '%s'\n", devnode); err = util_unlink_secure(udev, devnode); if (err == 0) util_delete_path(udev, devnode); /* remove /dev/{block,char}/$major:$minor */ snprintf(filename, sizeof(filename), "%s/%s/%u:%u", udev_get_dev_path(udev), strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char", major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev))); unlink(filename); out: return err; }