562 lines
21 KiB
C
562 lines
21 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "device-nodes.h"
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#include "device-private.h"
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#include "device-util.h"
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "format-util.h"
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#include "fs-util.h"
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#include "libudev-util.h"
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#include "mkdir.h"
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#include "path-util.h"
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#include "selinux-util.h"
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#include "smack-util.h"
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#include "stat-util.h"
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#include "stdio-util.h"
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#include "string-util.h"
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#include "strxcpyx.h"
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#include "udev-node.h"
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#include "user-util.h"
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#define LINK_UPDATE_MAX_RETRIES 128
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static int node_symlink(sd_device *dev, const char *node, const char *slink) {
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_cleanup_free_ char *slink_dirname = NULL, *target = NULL;
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const char *id_filename, *slink_tmp;
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struct stat stats;
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int r;
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assert(dev);
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assert(node);
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assert(slink);
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slink_dirname = dirname_malloc(slink);
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if (!slink_dirname)
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return log_oom();
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/* use relative link */
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r = path_make_relative(slink_dirname, node, &target);
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if (r < 0)
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return log_device_error_errno(dev, r, "Failed to get relative path from '%s' to '%s': %m", slink, node);
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/* preserve link with correct target, do not replace node of other device */
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if (lstat(slink, &stats) == 0) {
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if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode))
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return log_device_error_errno(dev, SYNTHETIC_ERRNO(EOPNOTSUPP),
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"Conflicting device node '%s' found, link to '%s' will not be created.", slink, node);
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else if (S_ISLNK(stats.st_mode)) {
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_cleanup_free_ char *buf = NULL;
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if (readlink_malloc(slink, &buf) >= 0 &&
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streq(target, buf)) {
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log_device_debug(dev, "Preserve already existing symlink '%s' to '%s'", slink, target);
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(void) label_fix(slink, LABEL_IGNORE_ENOENT);
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(void) utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW);
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return 0;
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}
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}
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} else {
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log_device_debug(dev, "Creating symlink '%s' to '%s'", slink, target);
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do {
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r = mkdir_parents_label(slink, 0755);
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if (!IN_SET(r, 0, -ENOENT))
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break;
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mac_selinux_create_file_prepare(slink, S_IFLNK);
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if (symlink(target, slink) < 0)
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r = -errno;
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mac_selinux_create_file_clear();
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} while (r == -ENOENT);
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if (r == 0)
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return 0;
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if (r < 0)
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log_device_debug_errno(dev, r, "Failed to create symlink '%s' to '%s', trying to replace '%s': %m", slink, target, slink);
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}
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log_device_debug(dev, "Atomically replace '%s'", slink);
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r = device_get_id_filename(dev, &id_filename);
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if (r < 0)
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return log_device_error_errno(dev, r, "Failed to get id_filename: %m");
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slink_tmp = strjoina(slink, ".tmp-", id_filename);
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(void) unlink(slink_tmp);
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do {
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r = mkdir_parents_label(slink_tmp, 0755);
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if (!IN_SET(r, 0, -ENOENT))
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break;
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mac_selinux_create_file_prepare(slink_tmp, S_IFLNK);
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if (symlink(target, slink_tmp) < 0)
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r = -errno;
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mac_selinux_create_file_clear();
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} while (r == -ENOENT);
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if (r < 0)
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return log_device_error_errno(dev, r, "Failed to create symlink '%s' to '%s': %m", slink_tmp, target);
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if (rename(slink_tmp, slink) < 0) {
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r = log_device_error_errno(dev, errno, "Failed to rename '%s' to '%s': %m", slink_tmp, slink);
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(void) unlink(slink_tmp);
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} else
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/* Tell caller that we replaced already existing symlink. */
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r = 1;
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return r;
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}
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/* find device node of device with highest priority */
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static int link_find_prioritized(sd_device *dev, bool add, const char *stackdir, char **ret) {
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_cleanup_closedir_ DIR *dir = NULL;
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_cleanup_free_ char *target = NULL;
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struct dirent *dent;
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int r, priority = 0;
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assert(!add || dev);
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assert(stackdir);
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assert(ret);
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if (add) {
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const char *devnode;
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r = device_get_devlink_priority(dev, &priority);
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if (r < 0)
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return r;
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r = sd_device_get_devname(dev, &devnode);
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if (r < 0)
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return r;
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target = strdup(devnode);
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if (!target)
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return -ENOMEM;
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}
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dir = opendir(stackdir);
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if (!dir) {
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if (target) {
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*ret = TAKE_PTR(target);
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return 0;
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}
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return -errno;
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}
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FOREACH_DIRENT_ALL(dent, dir, break) {
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_cleanup_(sd_device_unrefp) sd_device *dev_db = NULL;
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const char *devnode, *id_filename;
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int db_prio = 0;
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if (dent->d_name[0] == '\0')
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break;
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if (dent->d_name[0] == '.')
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continue;
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log_device_debug(dev, "Found '%s' claiming '%s'", dent->d_name, stackdir);
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if (device_get_id_filename(dev, &id_filename) < 0)
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continue;
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/* did we find ourself? */
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if (streq(dent->d_name, id_filename))
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continue;
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if (sd_device_new_from_device_id(&dev_db, dent->d_name) < 0)
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continue;
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if (sd_device_get_devname(dev_db, &devnode) < 0)
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continue;
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if (device_get_devlink_priority(dev_db, &db_prio) < 0)
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continue;
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if (target && db_prio <= priority)
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continue;
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log_device_debug(dev_db, "Device claims priority %i for '%s'", db_prio, stackdir);
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r = free_and_strdup(&target, devnode);
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if (r < 0)
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return r;
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priority = db_prio;
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}
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if (!target)
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return -ENOENT;
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*ret = TAKE_PTR(target);
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return 0;
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}
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static size_t escape_path(const char *src, char *dest, size_t size) {
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size_t i, j;
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assert(src);
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assert(dest);
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for (i = 0, j = 0; src[i] != '\0'; i++) {
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if (src[i] == '/') {
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if (j+4 >= size) {
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j = 0;
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break;
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}
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memcpy(&dest[j], "\\x2f", 4);
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j += 4;
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} else if (src[i] == '\\') {
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if (j+4 >= size) {
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j = 0;
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break;
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}
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memcpy(&dest[j], "\\x5c", 4);
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j += 4;
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} else {
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if (j+1 >= size) {
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j = 0;
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break;
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}
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dest[j] = src[i];
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j++;
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}
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}
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dest[j] = '\0';
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return j;
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}
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/* manage "stack of names" with possibly specified device priorities */
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static int link_update(sd_device *dev, const char *slink, bool add) {
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_cleanup_free_ char *target = NULL, *filename = NULL, *dirname = NULL;
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char name_enc[PATH_MAX];
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const char *id_filename;
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int i, r, retries;
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assert(dev);
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assert(slink);
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r = device_get_id_filename(dev, &id_filename);
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if (r < 0)
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return log_device_debug_errno(dev, r, "Failed to get id_filename: %m");
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escape_path(slink + STRLEN("/dev"), name_enc, sizeof(name_enc));
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dirname = path_join("/run/udev/links/", name_enc);
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if (!dirname)
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return log_oom();
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filename = path_join(dirname, id_filename);
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if (!filename)
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return log_oom();
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if (!add) {
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if (unlink(filename) == 0)
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(void) rmdir(dirname);
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} else
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for (;;) {
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_cleanup_close_ int fd = -1;
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r = mkdir_parents(filename, 0755);
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if (!IN_SET(r, 0, -ENOENT))
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return r;
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fd = open(filename, O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444);
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if (fd >= 0)
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break;
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if (errno != ENOENT)
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return -errno;
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}
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/* If the database entry is not written yet we will just do one iteration and possibly wrong symlink
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* will be fixed in the second invocation. */
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retries = sd_device_get_is_initialized(dev) > 0 ? LINK_UPDATE_MAX_RETRIES : 1;
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for (i = 0; i < retries; i++) {
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struct stat st1 = {}, st2 = {};
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r = stat(dirname, &st1);
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if (r < 0 && errno != ENOENT)
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return -errno;
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r = link_find_prioritized(dev, add, dirname, &target);
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if (r == -ENOENT) {
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log_device_debug(dev, "No reference left, removing '%s'", slink);
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if (unlink(slink) == 0)
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(void) rmdir_parents(slink, "/");
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break;
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} else if (r < 0)
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return log_device_error_errno(dev, r, "Failed to determine highest priority symlink: %m");
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r = node_symlink(dev, target, slink);
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if (r < 0) {
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(void) unlink(filename);
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break;
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} else if (r == 1)
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/* We have replaced already existing symlink, possibly there is some other device trying
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* to claim the same symlink. Let's do one more iteration to give us a chance to fix
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* the error if other device actually claims the symlink with higher priority. */
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continue;
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/* Skip the second stat() if the first failed, stat_inode_unmodified() would return false regardless. */
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if ((st1.st_mode & S_IFMT) != 0) {
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r = stat(dirname, &st2);
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if (r < 0 && errno != ENOENT)
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return -errno;
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if (stat_inode_unmodified(&st1, &st2))
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break;
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}
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}
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return i < LINK_UPDATE_MAX_RETRIES ? 0 : -ELOOP;
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}
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int udev_node_update_old_links(sd_device *dev, sd_device *dev_old) {
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const char *name, *devpath;
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int r;
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assert(dev);
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assert(dev_old);
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r = sd_device_get_devpath(dev, &devpath);
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if (r < 0)
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return log_device_debug_errno(dev, r, "Failed to get devpath: %m");
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/* update possible left-over symlinks */
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FOREACH_DEVICE_DEVLINK(dev_old, name) {
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const char *name_current;
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bool found = false;
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/* check if old link name still belongs to this device */
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FOREACH_DEVICE_DEVLINK(dev, name_current)
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if (streq(name, name_current)) {
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found = true;
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break;
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}
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if (found)
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continue;
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log_device_debug(dev, "Updating old name, '%s' no longer belonging to '%s'",
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name, devpath);
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link_update(dev, name, false);
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}
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return 0;
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}
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static int node_permissions_apply(sd_device *dev, bool apply_mac,
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mode_t mode, uid_t uid, gid_t gid,
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OrderedHashmap *seclabel_list) {
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const char *devnode, *subsystem, *id_filename = NULL;
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bool apply_mode, apply_uid, apply_gid;
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_cleanup_close_ int node_fd = -1;
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struct stat stats;
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dev_t devnum;
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int r;
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assert(dev);
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r = sd_device_get_devname(dev, &devnode);
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if (r < 0)
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return log_device_debug_errno(dev, r, "Failed to get devname: %m");
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r = sd_device_get_subsystem(dev, &subsystem);
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if (r < 0)
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return log_device_debug_errno(dev, r, "Failed to get subsystem: %m");
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r = sd_device_get_devnum(dev, &devnum);
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if (r < 0)
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return log_device_debug_errno(dev, r, "Failed to get devnum: %m");
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(void) device_get_id_filename(dev, &id_filename);
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if (streq(subsystem, "block"))
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mode |= S_IFBLK;
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else
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mode |= S_IFCHR;
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node_fd = open(devnode, O_PATH|O_NOFOLLOW|O_CLOEXEC);
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if (node_fd < 0) {
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if (errno == ENOENT) {
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log_device_debug_errno(dev, errno, "Device node %s is missing, skipping handling.", devnode);
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return 0; /* This is necessarily racey, so ignore missing the device */
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}
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return log_device_debug_errno(dev, errno, "Cannot open node %s: %m", devnode);
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}
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if (fstat(node_fd, &stats) < 0)
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return log_device_debug_errno(dev, errno, "cannot stat() node %s: %m", devnode);
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if ((mode != MODE_INVALID && (stats.st_mode & S_IFMT) != (mode & S_IFMT)) || stats.st_rdev != devnum) {
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log_device_debug(dev, "Found node '%s' with non-matching devnum %s, skipping handling.",
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devnode, id_filename);
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return 0; /* We might process a device that already got replaced by the time we have a look
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* at it, handle this gracefully and step away. */
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}
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apply_mode = mode != MODE_INVALID && (stats.st_mode & 0777) != (mode & 0777);
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apply_uid = uid_is_valid(uid) && stats.st_uid != uid;
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apply_gid = gid_is_valid(gid) && stats.st_gid != gid;
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if (apply_mode || apply_uid || apply_gid || apply_mac) {
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bool selinux = false, smack = false;
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const char *name, *label;
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if (apply_mode || apply_uid || apply_gid) {
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log_device_debug(dev, "Setting permissions %s, uid=" UID_FMT ", gid=" GID_FMT ", mode=%#o",
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devnode,
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uid_is_valid(uid) ? uid : stats.st_uid,
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gid_is_valid(gid) ? gid : stats.st_gid,
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mode != MODE_INVALID ? mode & 0777 : stats.st_mode & 0777);
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r = fchmod_and_chown(node_fd, mode, uid, gid);
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if (r < 0)
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log_device_full_errno(dev, r == -ENOENT ? LOG_DEBUG : LOG_ERR, r,
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"Failed to set owner/mode of %s to uid=" UID_FMT
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", gid=" GID_FMT ", mode=%#o: %m",
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devnode,
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uid_is_valid(uid) ? uid : stats.st_uid,
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gid_is_valid(gid) ? gid : stats.st_gid,
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mode != MODE_INVALID ? mode & 0777 : stats.st_mode & 0777);
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} else
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log_device_debug(dev, "Preserve permissions of %s, uid=" UID_FMT ", gid=" GID_FMT ", mode=%#o",
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devnode,
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uid_is_valid(uid) ? uid : stats.st_uid,
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gid_is_valid(gid) ? gid : stats.st_gid,
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mode != MODE_INVALID ? mode & 0777 : stats.st_mode & 0777);
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/* apply SECLABEL{$module}=$label */
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ORDERED_HASHMAP_FOREACH_KEY(label, name, seclabel_list) {
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int q;
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if (streq(name, "selinux")) {
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selinux = true;
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q = mac_selinux_apply_fd(node_fd, devnode, label);
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if (q < 0)
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log_device_full_errno(dev, q == -ENOENT ? LOG_DEBUG : LOG_ERR, q,
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"SECLABEL: failed to set SELinux label '%s': %m", label);
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else
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log_device_debug(dev, "SECLABEL: set SELinux label '%s'", label);
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} else if (streq(name, "smack")) {
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smack = true;
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q = mac_smack_apply_fd(node_fd, SMACK_ATTR_ACCESS, label);
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if (q < 0)
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log_device_full_errno(dev, q == -ENOENT ? LOG_DEBUG : LOG_ERR, q,
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"SECLABEL: failed to set SMACK label '%s': %m", label);
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else
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log_device_debug(dev, "SECLABEL: set SMACK label '%s'", label);
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} else
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log_device_error(dev, "SECLABEL: unknown subsystem, ignoring '%s'='%s'", name, label);
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}
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/* set the defaults */
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if (!selinux)
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(void) mac_selinux_fix_fd(node_fd, devnode, LABEL_IGNORE_ENOENT);
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if (!smack)
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(void) mac_smack_apply_fd(node_fd, SMACK_ATTR_ACCESS, NULL);
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}
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/* always update timestamp when we re-use the node, like on media change events */
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r = futimens_opath(node_fd, NULL);
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if (r < 0)
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log_device_debug_errno(dev, r, "Failed to adjust timestamp of node %s: %m", devnode);
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return r;
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}
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static int xsprintf_dev_num_path_from_sd_device(sd_device *dev, char **ret) {
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char filename[DEV_NUM_PATH_MAX], *s;
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const char *subsystem;
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dev_t devnum;
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int r;
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assert(ret);
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r = sd_device_get_subsystem(dev, &subsystem);
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if (r < 0)
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return r;
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r = sd_device_get_devnum(dev, &devnum);
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if (r < 0)
|
|
return r;
|
|
|
|
xsprintf_dev_num_path(filename,
|
|
streq(subsystem, "block") ? "block" : "char",
|
|
devnum);
|
|
|
|
s = strdup(filename);
|
|
if (!s)
|
|
return -ENOMEM;
|
|
|
|
*ret = s;
|
|
return 0;
|
|
}
|
|
|
|
int udev_node_add(sd_device *dev, bool apply,
|
|
mode_t mode, uid_t uid, gid_t gid,
|
|
OrderedHashmap *seclabel_list) {
|
|
const char *devnode, *devlink;
|
|
_cleanup_free_ char *filename = NULL;
|
|
int r;
|
|
|
|
assert(dev);
|
|
|
|
r = sd_device_get_devname(dev, &devnode);
|
|
if (r < 0)
|
|
return log_device_debug_errno(dev, r, "Failed to get devnode: %m");
|
|
|
|
if (DEBUG_LOGGING) {
|
|
const char *id_filename = NULL;
|
|
|
|
(void) device_get_id_filename(dev, &id_filename);
|
|
log_device_debug(dev, "Handling device node '%s', devnum=%s", devnode, strnull(id_filename));
|
|
}
|
|
|
|
r = node_permissions_apply(dev, apply, mode, uid, gid, seclabel_list);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = xsprintf_dev_num_path_from_sd_device(dev, &filename);
|
|
if (r < 0)
|
|
return log_device_debug_errno(dev, r, "Failed to get device path: %m");
|
|
|
|
/* always add /dev/{block,char}/$major:$minor */
|
|
(void) node_symlink(dev, devnode, filename);
|
|
|
|
/* create/update symlinks, add symlinks to name index */
|
|
FOREACH_DEVICE_DEVLINK(dev, devlink) {
|
|
r = link_update(dev, devlink, true);
|
|
if (r < 0)
|
|
log_device_info_errno(dev, r, "Failed to update device symlinks: %m");
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int udev_node_remove(sd_device *dev) {
|
|
_cleanup_free_ char *filename = NULL;
|
|
const char *devlink;
|
|
int r;
|
|
|
|
assert(dev);
|
|
|
|
/* remove/update symlinks, remove symlinks from name index */
|
|
FOREACH_DEVICE_DEVLINK(dev, devlink) {
|
|
r = link_update(dev, devlink, false);
|
|
if (r < 0)
|
|
log_device_info_errno(dev, r, "Failed to update device symlinks: %m");
|
|
}
|
|
|
|
r = xsprintf_dev_num_path_from_sd_device(dev, &filename);
|
|
if (r < 0)
|
|
return log_device_debug_errno(dev, r, "Failed to get device path: %m");
|
|
|
|
/* remove /dev/{block,char}/$major:$minor */
|
|
(void) unlink(filename);
|
|
|
|
return 0;
|
|
}
|