diff options
Diffstat (limited to 'src/grp-udev/libudev-core/udev-node.c')
| -rw-r--r-- | src/grp-udev/libudev-core/udev-node.c | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/src/grp-udev/libudev-core/udev-node.c b/src/grp-udev/libudev-core/udev-node.c new file mode 100644 index 0000000000..9577ae069e --- /dev/null +++ b/src/grp-udev/libudev-core/udev-node.c @@ -0,0 +1,375 @@ +/* + * Copyright (C) 2003-2013 Kay Sievers <kay@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 <dirent.h> +#include <errno.h> +#include <fcntl.h> +#include <stdbool.h> +#include <stddef.h> +#include <stdio.h> +#include <string.h> +#include <sys/stat.h> +#include <unistd.h> + +#include "systemd-basic/formats-util.h" +#include "systemd-basic/fs-util.h" +#include "systemd-basic/selinux-util.h" +#include "systemd-basic/smack-util.h" +#include "systemd-basic/stdio-util.h" +#include "systemd-basic/string-util.h" +#include "udev.h" + +static int node_symlink(struct udev_device *dev, 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 + 32]; + 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 = strpcpy(&s, l, "../"); + i++; + } + l = 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)) { + log_error("conflicting device node '%s' found, link to '%s' will not be created", slink, node); + goto exit; + } else if (S_ISLNK(stats.st_mode)) { + char buf[UTIL_PATH_SIZE]; + int len; + + len = readlink(slink, buf, sizeof(buf)); + if (len > 0 && len < (int)sizeof(buf)) { + buf[len] = '\0'; + if (streq(target, buf)) { + log_debug("preserve already existing symlink '%s' to '%s'", slink, target); + label_fix(slink, true, false); + utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW); + goto exit; + } + } + } + } else { + log_debug("creating symlink '%s' to '%s'", slink, target); + do { + err = mkdir_parents_label(slink, 0755); + if (err != 0 && err != -ENOENT) + break; + mac_selinux_create_file_prepare(slink, S_IFLNK); + err = symlink(target, slink); + if (err != 0) + err = -errno; + mac_selinux_create_file_clear(); + } while (err == -ENOENT); + if (err == 0) + goto exit; + } + + log_debug("atomically replace '%s'", slink); + strscpyl(slink_tmp, sizeof(slink_tmp), slink, ".tmp-", udev_device_get_id_filename(dev), NULL); + unlink(slink_tmp); + do { + err = mkdir_parents_label(slink_tmp, 0755); + if (err != 0 && err != -ENOENT) + break; + mac_selinux_create_file_prepare(slink_tmp, S_IFLNK); + err = symlink(target, slink_tmp); + if (err != 0) + err = -errno; + mac_selinux_create_file_clear(); + } while (err == -ENOENT); + if (err != 0) { + log_error_errno(errno, "symlink '%s' '%s' failed: %m", target, slink_tmp); + goto exit; + } + err = rename(slink_tmp, slink); + if (err != 0) { + log_error_errno(errno, "rename '%s' '%s' failed: %m", 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); + 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; + + log_debug("found '%s' claiming '%s'", dent->d_name, stackdir); + + /* did we find ourself? */ + if (streq(dent->d_name, udev_device_get_id_filename(dev))) + continue; + + dev_db = udev_device_new_from_device_id(udev, dent->d_name); + if (dev_db != NULL) { + const char *devnode; + + devnode = udev_device_get_devnode(dev_db); + if (devnode != NULL) { + if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) { + log_debug("'%s' claims priority %i for '%s'", + udev_device_get_syspath(dev_db), udev_device_get_devlink_priority(dev_db), stackdir); + priority = udev_device_get_devlink_priority(dev_db); + 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) { + 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]; + + util_path_encode(slink + strlen("/dev"), name_enc, sizeof(name_enc)); + strscpyl(dirname, sizeof(dirname), "/run/udev/links/", name_enc, NULL); + strscpyl(filename, sizeof(filename), dirname, "/", udev_device_get_id_filename(dev), NULL); + + if (!add && unlink(filename) == 0) + rmdir(dirname); + + target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf)); + if (target == NULL) { + log_debug("no reference left, remove '%s'", slink); + if (unlink(slink) == 0) + rmdir_parents(slink, "/"); + } else { + log_debug("creating link '%s' to '%s'", slink, target); + node_symlink(dev, target, slink); + } + + if (add) { + int err; + + do { + int fd; + + err = mkdir_parents(filename, 0755); + 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_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 (streq(name, name_current)) { + found = 1; + break; + } + } + if (found) + continue; + + log_debug("update old name, '%s' no longer belonging to '%s'", + name, udev_device_get_devpath(dev)); + link_update(dev, name, false); + } +} + +static int node_permissions_apply(struct udev_device *dev, bool apply, + mode_t mode, uid_t uid, gid_t gid, + struct udev_list *seclabel_list) { + const char *devnode = udev_device_get_devnode(dev); + dev_t devnum = udev_device_get_devnum(dev); + struct stat stats; + struct udev_list_entry *entry; + int err = 0; + + if (streq(udev_device_get_subsystem(dev), "block")) + mode |= S_IFBLK; + else + mode |= S_IFCHR; + + if (lstat(devnode, &stats) != 0) { + err = log_debug_errno(errno, "can not stat() node '%s' (%m)", devnode); + goto out; + } + + if (((stats.st_mode & S_IFMT) != (mode & S_IFMT)) || (stats.st_rdev != devnum)) { + err = -EEXIST; + log_debug("found node '%s' with non-matching devnum %s, skip handling", + udev_device_get_devnode(dev), udev_device_get_id_filename(dev)); + goto out; + } + + if (apply) { + bool selinux = false; + bool smack = false; + + if ((stats.st_mode & 0777) != (mode & 0777) || stats.st_uid != uid || stats.st_gid != gid) { + log_debug("set permissions %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid); + err = chmod(devnode, mode); + if (err < 0) + log_warning_errno(errno, "setting mode of %s to %#o failed: %m", devnode, mode); + err = chown(devnode, uid, gid); + if (err < 0) + log_warning_errno(errno, "setting owner of %s to uid=%u, gid=%u failed: %m", devnode, uid, gid); + } else { + log_debug("preserve permissions %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid); + } + + /* apply SECLABEL{$module}=$label */ + udev_list_entry_foreach(entry, udev_list_get_entry(seclabel_list)) { + const char *name, *label; + int r; + + name = udev_list_entry_get_name(entry); + label = udev_list_entry_get_value(entry); + + if (streq(name, "selinux")) { + selinux = true; + + r = mac_selinux_apply(devnode, label); + if (r < 0) + log_error_errno(r, "SECLABEL: failed to set SELinux label '%s': %m", label); + else + log_debug("SECLABEL: set SELinux label '%s'", label); + + } else if (streq(name, "smack")) { + smack = true; + + r = mac_smack_apply(devnode, SMACK_ATTR_ACCESS, label); + if (r < 0) + log_error_errno(r, "SECLABEL: failed to set SMACK label '%s': %m", label); + else + log_debug("SECLABEL: set SMACK label '%s'", label); + + } else + log_error("SECLABEL: unknown subsystem, ignoring '%s'='%s'", name, label); + } + + /* set the defaults */ + if (!selinux) + mac_selinux_fix(devnode, true, false); + if (!smack) + mac_smack_apply(devnode, SMACK_ATTR_ACCESS, NULL); + } + + /* always update timestamp when we re-use the node, like on media change events */ + utimensat(AT_FDCWD, devnode, NULL, 0); +out: + return err; +} + +void udev_node_add(struct udev_device *dev, bool apply, + mode_t mode, uid_t uid, gid_t gid, + struct udev_list *seclabel_list) { + char filename[sizeof("/dev/block/:") + 2*DECIMAL_STR_MAX(unsigned)]; + struct udev_list_entry *list_entry; + + log_debug("handling device node '%s', devnum=%s, mode=%#o, uid="UID_FMT", gid="GID_FMT, + udev_device_get_devnode(dev), udev_device_get_id_filename(dev), mode, uid, gid); + + if (node_permissions_apply(dev, apply, mode, uid, gid, seclabel_list) < 0) + return; + + /* always add /dev/{block,char}/$major:$minor */ + xsprintf(filename, "/dev/%s/%u:%u", + streq(udev_device_get_subsystem(dev), "block") ? "block" : "char", + major(udev_device_get_devnum(dev)), + minor(udev_device_get_devnum(dev))); + node_symlink(dev, 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)) + link_update(dev, udev_list_entry_get_name(list_entry), true); +} + +void udev_node_remove(struct udev_device *dev) { + struct udev_list_entry *list_entry; + char filename[sizeof("/dev/block/:") + 2*DECIMAL_STR_MAX(unsigned)]; + + /* 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), false); + + /* remove /dev/{block,char}/$major:$minor */ + xsprintf(filename, "/dev/%s/%u:%u", + streq(udev_device_get_subsystem(dev), "block") ? "block" : "char", + major(udev_device_get_devnum(dev)), + minor(udev_device_get_devnum(dev))); + unlink(filename); +} |