diff options
Diffstat (limited to '')
| -rw-r--r-- | src/udev/udev-node.c | 708 |
1 files changed, 708 insertions, 0 deletions
diff --git a/src/udev/udev-node.c b/src/udev/udev-node.c new file mode 100644 index 0000000..9e34ea6 --- /dev/null +++ b/src/udev/udev-node.c @@ -0,0 +1,708 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include <sys/file.h> + +#include "sd-id128.h" + +#include "alloc-util.h" +#include "device-private.h" +#include "device-util.h" +#include "devnum-util.h" +#include "dirent-util.h" +#include "escape.h" +#include "fd-util.h" +#include "format-util.h" +#include "fs-util.h" +#include "hexdecoct.h" +#include "label.h" +#include "mkdir-label.h" +#include "parse-util.h" +#include "path-util.h" +#include "selinux-util.h" +#include "smack-util.h" +#include "stat-util.h" +#include "string-util.h" +#include "udev-node.h" +#include "user-util.h" + +#define UDEV_NODE_HASH_KEY SD_ID128_MAKE(b9,6a,f1,ce,40,31,44,1a,9e,19,ec,8b,ae,f3,e3,2f) + +int udev_node_cleanup(void) { + _cleanup_closedir_ DIR *dir = NULL; + + /* This must not be called when any workers exist. It would cause a race between mkdir() called + * by stack_directory_lock() and unlinkat() called by this. */ + + dir = opendir("/run/udev/links"); + if (!dir) { + if (errno == ENOENT) + return 0; + + return log_debug_errno(errno, "Failed to open directory '/run/udev/links', ignoring: %m"); + } + + FOREACH_DIRENT_ALL(de, dir, break) { + _cleanup_free_ char *lockfile = NULL; + + if (de->d_name[0] == '.') + continue; + + if (de->d_type != DT_DIR) + continue; + + /* As commented in the above, this is called when no worker exists, hence the file is not + * locked. On a later uevent, the lock file will be created if necessary. So, we can safely + * remove the file now. */ + lockfile = path_join(de->d_name, ".lock"); + if (!lockfile) + return log_oom_debug(); + + if (unlinkat(dirfd(dir), lockfile, 0) < 0 && errno != ENOENT) { + log_debug_errno(errno, "Failed to remove '/run/udev/links/%s', ignoring: %m", lockfile); + continue; + } + + if (unlinkat(dirfd(dir), de->d_name, AT_REMOVEDIR) < 0 && errno != ENOTEMPTY) + log_debug_errno(errno, "Failed to remove '/run/udev/links/%s', ignoring: %m", de->d_name); + } + + return 0; +} + +static int node_symlink(sd_device *dev, const char *devnode, const char *slink) { + struct stat st; + int r; + + assert(dev); + assert(slink); + + if (!devnode) { + r = sd_device_get_devname(dev, &devnode); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get device node: %m"); + } + + if (lstat(slink, &st) >= 0) { + if (!S_ISLNK(st.st_mode)) + return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EEXIST), + "Conflicting inode '%s' found, symlink to '%s' will not be created.", + slink, devnode); + } else if (errno != ENOENT) + return log_device_debug_errno(dev, errno, "Failed to lstat() '%s': %m", slink); + + r = mkdir_parents_label(slink, 0755); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to create parent directory of '%s': %m", slink); + + /* use relative link */ + r = symlink_atomic_full_label(devnode, slink, /* make_relative = */ true); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to create symlink '%s' to '%s': %m", slink, devnode); + + log_device_debug(dev, "Successfully created symlink '%s' to '%s'", slink, devnode); + return 0; +} + +static int stack_directory_read_one(int dirfd, const char *id, bool is_symlink, char **devnode, int *priority) { + int tmp_prio, r; + + assert(dirfd >= 0); + assert(id); + assert(devnode); + assert(priority); + + if (is_symlink) { + _cleanup_free_ char *buf = NULL; + char *colon; + + /* New format. The devnode and priority can be obtained from symlink. */ + + r = readlinkat_malloc(dirfd, id, &buf); + if (r < 0) + return r; + + colon = strchr(buf, ':'); + if (!colon || colon == buf) + return -EINVAL; + + *colon = '\0'; + + /* Of course, this check is racy, but it is not necessary to be perfect. Even if the device + * node will be removed after this check, we will receive 'remove' uevent, and the invalid + * symlink will be removed during processing the event. The check is just for shortening the + * timespan that the symlink points to a non-existing device node. */ + if (access(colon + 1, F_OK) < 0) + return -errno; + + r = safe_atoi(buf, &tmp_prio); + if (r < 0) + return r; + + if (*devnode && tmp_prio <= *priority) + return 0; /* Unchanged */ + + r = free_and_strdup(devnode, colon + 1); + if (r < 0) + return r; + + } else { + _cleanup_(sd_device_unrefp) sd_device *dev = NULL; + const char *val; + + /* Old format. The devnode and priority must be obtained from uevent and udev database. */ + + r = sd_device_new_from_device_id(&dev, id); + if (r < 0) + return r; + + r = device_get_devlink_priority(dev, &tmp_prio); + if (r < 0) + return r; + + if (*devnode && tmp_prio <= *priority) + return 0; /* Unchanged */ + + r = sd_device_get_devname(dev, &val); + if (r < 0) + return r; + + r = free_and_strdup(devnode, val); + if (r < 0) + return r; + } + + *priority = tmp_prio; + return 1; /* Updated */ +} + +static int stack_directory_find_prioritized_devnode(sd_device *dev, const char *dirname, bool add, char **ret) { + _cleanup_closedir_ DIR *dir = NULL; + _cleanup_free_ char *devnode = NULL; + int r, priority = 0; + const char *id; + + assert(dev); + assert(dirname); + assert(ret); + + /* Find device node of device with highest priority. This returns 1 if a device found, 0 if no + * device found, or a negative errno on error. */ + + if (add) { + const char *n; + + r = device_get_devlink_priority(dev, &priority); + if (r < 0) + return r; + + r = sd_device_get_devname(dev, &n); + if (r < 0) + return r; + + devnode = strdup(n); + if (!devnode) + return -ENOMEM; + } + + dir = opendir(dirname); + if (!dir) + return -errno; + + r = device_get_device_id(dev, &id); + if (r < 0) + return r; + + FOREACH_DIRENT_ALL(de, dir, break) { + if (de->d_name[0] == '.') + continue; + + /* skip ourself */ + if (streq(de->d_name, id)) + continue; + + if (!IN_SET(de->d_type, DT_LNK, DT_REG)) + continue; + + r = stack_directory_read_one(dirfd(dir), de->d_name, /* is_symlink = */ de->d_type == DT_LNK, &devnode, &priority); + if (r < 0) { + log_debug_errno(r, "Failed to read '%s/%s', ignoring: %m", dirname, de->d_name); + continue; + } + } + + *ret = TAKE_PTR(devnode); + return !!*ret; +} + +static int stack_directory_update(sd_device *dev, int fd, bool add) { + const char *id; + int r; + + assert(dev); + assert(fd >= 0); + + r = device_get_device_id(dev, &id); + if (r < 0) + return r; + + if (add) { + _cleanup_free_ char *data = NULL, *buf = NULL; + const char *devname; + int priority; + + r = sd_device_get_devname(dev, &devname); + if (r < 0) + return r; + + r = device_get_devlink_priority(dev, &priority); + if (r < 0) + return r; + + if (asprintf(&data, "%i:%s", priority, devname) < 0) + return -ENOMEM; + + if (readlinkat_malloc(fd, id, &buf) >= 0 && streq(buf, data)) + return 0; /* Unchanged. */ + + (void) unlinkat(fd, id, 0); + + if (symlinkat(data, fd, id) < 0) + return -errno; + + } else { + if (unlinkat(fd, id, 0) < 0) { + if (errno == ENOENT) + return 0; /* Unchanged. */ + return -errno; + } + } + + return 1; /* Updated. */ +} + +static int stack_directory_open(const char *dirname) { + _cleanup_close_ int fd = -1; + int r; + + assert(dirname); + + r = mkdir_parents(dirname, 0755); + if (r < 0) + return r; + + fd = open_mkdir_at(AT_FDCWD, dirname, O_CLOEXEC | O_DIRECTORY | O_NOFOLLOW | O_RDONLY, 0755); + if (fd < 0) + return fd; + + return TAKE_FD(fd); +} + +static int stack_directory_lock(int dirfd) { + _cleanup_close_ int fd = -1; + + assert(dirfd >= 0); + + fd = openat(dirfd, ".lock", O_CLOEXEC | O_NOFOLLOW | O_RDONLY | O_CREAT, 0600); + if (fd < 0) + return -errno; + + if (flock(fd, LOCK_EX) < 0) + return -errno; + + return TAKE_FD(fd); +} + +size_t udev_node_escape_path(const char *src, char *dest, size_t size) { + size_t i, j; + uint64_t h; + + assert(src); + assert(dest); + assert(size >= 12); + + for (i = 0, j = 0; src[i] != '\0'; i++) { + if (src[i] == '/') { + if (j+4 >= size - 12 + 1) + goto toolong; + memcpy(&dest[j], "\\x2f", 4); + j += 4; + } else if (src[i] == '\\') { + if (j+4 >= size - 12 + 1) + goto toolong; + memcpy(&dest[j], "\\x5c", 4); + j += 4; + } else { + if (j+1 >= size - 12 + 1) + goto toolong; + dest[j] = src[i]; + j++; + } + } + dest[j] = '\0'; + return j; + +toolong: + /* If the input path is too long to encode as a filename, then let's suffix with a string + * generated from the hash of the path. */ + + h = siphash24_string(src, UDEV_NODE_HASH_KEY.bytes); + + for (unsigned k = 0; k <= 10; k++) + dest[size - k - 2] = urlsafe_base64char((h >> (k * 6)) & 63); + + dest[size - 1] = '\0'; + return size - 1; +} + +static int stack_directory_get_name(const char *slink, char **ret) { + _cleanup_free_ char *s = NULL, *dirname = NULL; + char name_enc[NAME_MAX+1]; + const char *name; + + assert(slink); + assert(ret); + + s = strdup(slink); + if (!s) + return -ENOMEM; + + path_simplify(s); + + if (!path_is_normalized(s)) + return -EINVAL; + + name = path_startswith(s, "/dev"); + if (empty_or_root(name)) + return -EINVAL; + + udev_node_escape_path(name, name_enc, sizeof(name_enc)); + + dirname = path_join("/run/udev/links", name_enc); + if (!dirname) + return -ENOMEM; + + *ret = TAKE_PTR(dirname); + return 0; +} + +static int link_update(sd_device *dev, const char *slink, bool add) { + _cleanup_free_ char *dirname = NULL, *devnode = NULL; + _cleanup_close_ int dirfd = -1, lockfd = -1; + int r; + + assert(dev); + assert(slink); + + r = stack_directory_get_name(slink, &dirname); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to build stack directory name for '%s': %m", slink); + + dirfd = stack_directory_open(dirname); + if (dirfd < 0) + return log_device_debug_errno(dev, dirfd, "Failed to open stack directory '%s': %m", dirname); + + lockfd = stack_directory_lock(dirfd); + if (lockfd < 0) + return log_device_debug_errno(dev, lockfd, "Failed to lock stack directory '%s': %m", dirname); + + r = stack_directory_update(dev, dirfd, add); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to update stack directory '%s': %m", dirname); + + r = stack_directory_find_prioritized_devnode(dev, dirname, add, &devnode); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to determine device node with the highest priority for '%s': %m", slink); + if (r > 0) + return node_symlink(dev, devnode, slink); + + log_device_debug(dev, "No reference left for '%s', removing", slink); + + if (unlink(slink) < 0 && errno != ENOENT) + log_device_debug_errno(dev, errno, "Failed to remove '%s', ignoring: %m", slink); + + (void) rmdir_parents(slink, "/dev"); + + return 0; +} + +static int device_get_devpath_by_devnum(sd_device *dev, char **ret) { + const char *subsystem; + dev_t devnum; + int r; + + assert(dev); + assert(ret); + + r = sd_device_get_subsystem(dev, &subsystem); + if (r < 0) + return r; + + r = sd_device_get_devnum(dev, &devnum); + if (r < 0) + return r; + + return device_path_make_major_minor(streq(subsystem, "block") ? S_IFBLK : S_IFCHR, devnum, ret); +} + +int udev_node_update(sd_device *dev, sd_device *dev_old) { + _cleanup_free_ char *filename = NULL; + const char *devlink; + int r; + + assert(dev); + assert(dev_old); + + /* update possible left-over symlinks */ + FOREACH_DEVICE_DEVLINK(dev_old, devlink) { + /* check if old link name still belongs to this device */ + if (device_has_devlink(dev, devlink)) + continue; + + log_device_debug(dev, + "Removing/updating old device symlink '%s', which is no longer belonging to this device.", + devlink); + + r = link_update(dev, devlink, /* add = */ false); + if (r < 0) + log_device_warning_errno(dev, r, + "Failed to remove/update device symlink '%s', ignoring: %m", + devlink); + } + + /* create/update symlinks, add symlinks to name index */ + FOREACH_DEVICE_DEVLINK(dev, devlink) { + r = link_update(dev, devlink, /* add = */ true); + if (r < 0) + log_device_warning_errno(dev, r, + "Failed to create/update device symlink '%s', ignoring: %m", + devlink); + } + + r = device_get_devpath_by_devnum(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 */ + r = node_symlink(dev, NULL, filename); + if (r < 0) + return log_device_warning_errno(dev, r, "Failed to create device symlink '%s': %m", filename); + + 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, /* add = */ false); + if (r < 0) + log_device_warning_errno(dev, r, + "Failed to remove/update device symlink '%s', ignoring: %m", + devlink); + } + + r = device_get_devpath_by_devnum(dev, &filename); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get device path: %m"); + + /* remove /dev/{block,char}/$major:$minor */ + if (unlink(filename) < 0 && errno != ENOENT) + return log_device_debug_errno(dev, errno, "Failed to remove '%s': %m", filename); + + return 0; +} + +static int udev_node_apply_permissions_impl( + sd_device *dev, /* can be NULL, only used for logging. */ + int node_fd, + const char *devnode, + bool apply_mac, + mode_t mode, + uid_t uid, + gid_t gid, + OrderedHashmap *seclabel_list) { + + bool apply_mode, apply_uid, apply_gid; + struct stat stats; + int r; + + assert(node_fd >= 0); + assert(devnode); + + if (fstat(node_fd, &stats) < 0) + return log_device_debug_errno(dev, errno, "cannot stat() node %s: %m", devnode); + + /* If group is set, but mode is not set, "upgrade" mode for the group. */ + if (mode == MODE_INVALID && gid_is_valid(gid) && gid > 0) + mode = 0660; + + apply_mode = mode != MODE_INVALID && (stats.st_mode & 0777) != (mode & 0777); + apply_uid = uid_is_valid(uid) && stats.st_uid != uid; + apply_gid = gid_is_valid(gid) && stats.st_gid != gid; + + if (apply_mode || apply_uid || apply_gid || apply_mac) { + bool selinux = false, smack = false; + const char *name, *label; + + if (apply_mode || apply_uid || apply_gid) { + log_device_debug(dev, "Setting permissions %s, uid=" UID_FMT ", gid=" GID_FMT ", mode=%#o", + devnode, + uid_is_valid(uid) ? uid : stats.st_uid, + gid_is_valid(gid) ? gid : stats.st_gid, + mode != MODE_INVALID ? mode & 0777 : stats.st_mode & 0777); + + r = fchmod_and_chown(node_fd, mode, uid, gid); + if (r < 0) + log_device_full_errno(dev, r == -ENOENT ? LOG_DEBUG : LOG_ERR, r, + "Failed to set owner/mode of %s to uid=" UID_FMT + ", gid=" GID_FMT ", mode=%#o: %m", + devnode, + uid_is_valid(uid) ? uid : stats.st_uid, + gid_is_valid(gid) ? gid : stats.st_gid, + mode != MODE_INVALID ? mode & 0777 : stats.st_mode & 0777); + } else + log_device_debug(dev, "Preserve permissions of %s, uid=" UID_FMT ", gid=" GID_FMT ", mode=%#o", + devnode, + uid_is_valid(uid) ? uid : stats.st_uid, + gid_is_valid(gid) ? gid : stats.st_gid, + mode != MODE_INVALID ? mode & 0777 : stats.st_mode & 0777); + + /* apply SECLABEL{$module}=$label */ + ORDERED_HASHMAP_FOREACH_KEY(label, name, seclabel_list) { + int q; + + if (streq(name, "selinux")) { + selinux = true; + + q = mac_selinux_apply_fd(node_fd, devnode, label); + if (q < 0) + log_device_full_errno(dev, q == -ENOENT ? LOG_DEBUG : LOG_ERR, q, + "SECLABEL: failed to set SELinux label '%s': %m", label); + else + log_device_debug(dev, "SECLABEL: set SELinux label '%s'", label); + + } else if (streq(name, "smack")) { + smack = true; + + q = mac_smack_apply_fd(node_fd, SMACK_ATTR_ACCESS, label); + if (q < 0) + log_device_full_errno(dev, q == -ENOENT ? LOG_DEBUG : LOG_ERR, q, + "SECLABEL: failed to set SMACK label '%s': %m", label); + else + log_device_debug(dev, "SECLABEL: set SMACK label '%s'", label); + + } else + log_device_error(dev, "SECLABEL: unknown subsystem, ignoring '%s'='%s'", name, label); + } + + /* set the defaults */ + if (!selinux) + (void) mac_selinux_fix_full(node_fd, NULL, devnode, LABEL_IGNORE_ENOENT); + if (!smack) + (void) mac_smack_apply_fd(node_fd, SMACK_ATTR_ACCESS, NULL); + } + + /* always update timestamp when we re-use the node, like on media change events */ + r = futimens_opath(node_fd, NULL); + if (r < 0) + log_device_debug_errno(dev, r, "Failed to adjust timestamp of node %s: %m", devnode); + + return 0; +} + +int udev_node_apply_permissions( + sd_device *dev, + bool apply_mac, + mode_t mode, + uid_t uid, + gid_t gid, + OrderedHashmap *seclabel_list) { + + const char *devnode; + _cleanup_close_ int node_fd = -1; + int r; + + assert(dev); + + r = sd_device_get_devname(dev, &devnode); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get devname: %m"); + + node_fd = sd_device_open(dev, O_PATH|O_CLOEXEC); + if (node_fd < 0) { + if (ERRNO_IS_DEVICE_ABSENT(node_fd)) { + log_device_debug_errno(dev, node_fd, "Device node %s is missing, skipping handling.", devnode); + return 0; /* This is necessarily racey, so ignore missing the device */ + } + + return log_device_debug_errno(dev, node_fd, "Cannot open node %s: %m", devnode); + } + + return udev_node_apply_permissions_impl(dev, node_fd, devnode, apply_mac, mode, uid, gid, seclabel_list); +} + +int static_node_apply_permissions( + const char *name, + mode_t mode, + uid_t uid, + gid_t gid, + char **tags) { + + _cleanup_free_ char *unescaped_filename = NULL; + _cleanup_close_ int node_fd = -1; + const char *devnode; + struct stat stats; + int r; + + assert(name); + + if (uid == UID_INVALID && gid == GID_INVALID && mode == MODE_INVALID && !tags) + return 0; + + devnode = strjoina("/dev/", name); + + node_fd = open(devnode, O_PATH|O_CLOEXEC); + if (node_fd < 0) { + if (errno != ENOENT) + return log_error_errno(errno, "Failed to open %s: %m", devnode); + return 0; + } + + if (fstat(node_fd, &stats) < 0) + return log_error_errno(errno, "Failed to stat %s: %m", devnode); + + if (!S_ISBLK(stats.st_mode) && !S_ISCHR(stats.st_mode)) { + log_warning("%s is neither block nor character device, ignoring.", devnode); + return 0; + } + + if (!strv_isempty(tags)) { + unescaped_filename = xescape(name, "/."); + if (!unescaped_filename) + return log_oom(); + } + + /* export the tags to a directory as symlinks, allowing otherwise dead nodes to be tagged */ + STRV_FOREACH(t, tags) { + _cleanup_free_ char *p = NULL; + + p = path_join("/run/udev/static_node-tags/", *t, unescaped_filename); + if (!p) + return log_oom(); + + r = mkdir_parents(p, 0755); + if (r < 0) + return log_error_errno(r, "Failed to create parent directory for %s: %m", p); + + r = symlink(devnode, p); + if (r < 0 && errno != EEXIST) + return log_error_errno(errno, "Failed to create symlink %s -> %s: %m", p, devnode); + } + + return udev_node_apply_permissions_impl(NULL, node_fd, devnode, false, mode, uid, gid, NULL); +} |