/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include <errno.h> #include <stdlib.h> #include <sys/mount.h> #include <sys/statvfs.h> #include <unistd.h> #include "alloc-util.h" #include "bus-util.h" #include "cgroup-setup.h" #include "cgroup-util.h" #include "conf-files.h" #include "dev-setup.h" #include "dirent-util.h" #include "efi-loader.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "label-util.h" #include "log.h" #include "macro.h" #include "mkdir-label.h" #include "mount-setup.h" #include "mount-util.h" #include "mountpoint-util.h" #include "nulstr-util.h" #include "path-util.h" #include "recurse-dir.h" #include "set.h" #include "smack-util.h" #include "strv.h" #include "user-util.h" #include "virt.h" typedef enum MountMode { MNT_NONE = 0, MNT_FATAL = 1 << 0, MNT_IN_CONTAINER = 1 << 1, MNT_CHECK_WRITABLE = 1 << 2, MNT_FOLLOW_SYMLINK = 1 << 3, } MountMode; typedef struct MountPoint { const char *what; const char *where; const char *type; const char *options; unsigned long flags; bool (*condition_fn)(void); MountMode mode; } MountPoint; /* The first three entries we might need before SELinux is up. The * fourth (securityfs) is needed by IMA to load a custom policy. The * other ones we can delay until SELinux and IMA are loaded. When * SMACK is enabled we need smackfs, too, so it's a fifth one. */ #if ENABLE_SMACK #define N_EARLY_MOUNT 5 #else #define N_EARLY_MOUNT 4 #endif static bool check_recursiveprot_supported(void) { int r; if (!cg_is_unified_wanted()) return false; r = mount_option_supported("cgroup2", "memory_recursiveprot", NULL); if (r < 0) log_debug_errno(r, "Failed to determiner whether the 'memory_recursiveprot' mount option is supported, assuming not: %m"); else if (r == 0) log_debug("This kernel version does not support 'memory_recursiveprot', not using mount option."); return r > 0; } static const MountPoint mount_table[] = { { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_FATAL|MNT_IN_CONTAINER|MNT_FOLLOW_SYMLINK }, { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "devtmpfs", "/dev", "devtmpfs", "mode=0755" TMPFS_LIMITS_DEV, MS_NOSUID|MS_STRICTATIME, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "securityfs", "/sys/kernel/security", "securityfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_NONE }, #if ENABLE_SMACK { "smackfs", "/sys/fs/smackfs", "smackfs", "smackfsdef=*", MS_NOSUID|MS_NOEXEC|MS_NODEV, mac_smack_use, MNT_FATAL }, { "tmpfs", "/dev/shm", "tmpfs", "mode=01777,smackfsroot=*", MS_NOSUID|MS_NODEV|MS_STRICTATIME, mac_smack_use, MNT_FATAL }, #endif { "tmpfs", "/dev/shm", "tmpfs", "mode=01777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "devpts", "/dev/pts", "devpts", "mode=0620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, NULL, MNT_IN_CONTAINER }, #if ENABLE_SMACK { "tmpfs", "/run", "tmpfs", "mode=0755,smackfsroot=*" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME, mac_smack_use, MNT_FATAL }, #endif { "tmpfs", "/run", "tmpfs", "mode=0755" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate,memory_recursiveprot", MS_NOSUID|MS_NOEXEC|MS_NODEV, check_recursiveprot_supported, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, { "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate", MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, { "cgroup2", "/sys/fs/cgroup", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, { "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=0755" TMPFS_LIMITS_SYS_FS_CGROUP, MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER }, { "cgroup2", "/sys/fs/cgroup/unified", "cgroup2", "nsdelegate", MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_hybrid_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, { "cgroup2", "/sys/fs/cgroup/unified", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_hybrid_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd,xattr", MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_legacy_wanted, MNT_IN_CONTAINER }, { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER }, #if ENABLE_PSTORE { "pstore", "/sys/fs/pstore", "pstore", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_NONE }, #endif #if ENABLE_EFI { "efivarfs", "/sys/firmware/efi/efivars", "efivarfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, is_efi_boot, MNT_NONE }, #endif { "bpf", "/sys/fs/bpf", "bpf", "mode=0700", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_NONE, }, }; assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table)); bool mount_point_is_api(const char *path) { /* Checks if this mount point is considered "API", and hence * should be ignored */ for (size_t i = 0; i < ELEMENTSOF(mount_table); i ++) if (path_equal(path, mount_table[i].where)) return true; return path_startswith(path, "/sys/fs/cgroup/"); } bool mount_point_ignore(const char *path) { /* These are API file systems that might be mounted by other software, we just list them here so that * we know that we should ignore them. */ FOREACH_STRING(i, /* SELinux file systems */ "/sys/fs/selinux", /* Container bind mounts */ "/dev/console", "/proc/kmsg", "/proc/sys", "/proc/sys/kernel/random/boot_id") if (path_equal(path, i)) return true; if (path_startswith(path, "/run/host")) /* All mounts passed in from the container manager are * something we better ignore. */ return true; return false; } static int mount_one(const MountPoint *p, bool relabel) { int r, priority; assert(p); priority = (p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG; if (p->condition_fn && !p->condition_fn()) return 0; /* Relabel first, just in case */ if (relabel) (void) label_fix(p->where, LABEL_IGNORE_ENOENT|LABEL_IGNORE_EROFS); r = path_is_mount_point(p->where, NULL, AT_SYMLINK_FOLLOW); if (r < 0 && r != -ENOENT) { log_full_errno(priority, r, "Failed to determine whether %s is a mount point: %m", p->where); return (p->mode & MNT_FATAL) ? r : 0; } if (r > 0) return 0; /* Skip securityfs in a container */ if (!(p->mode & MNT_IN_CONTAINER) && detect_container() > 0) return 0; /* The access mode here doesn't really matter too much, since * the mounted file system will take precedence anyway. */ if (relabel) (void) mkdir_p_label(p->where, 0755); else (void) mkdir_p(p->where, 0755); log_debug("Mounting %s to %s of type %s with options %s.", p->what, p->where, p->type, strna(p->options)); if (FLAGS_SET(p->mode, MNT_FOLLOW_SYMLINK)) r = mount_follow_verbose(priority, p->what, p->where, p->type, p->flags, p->options); else r = mount_nofollow_verbose(priority, p->what, p->where, p->type, p->flags, p->options); if (r < 0) return (p->mode & MNT_FATAL) ? r : 0; /* Relabel again, since we now mounted something fresh here */ if (relabel) (void) label_fix(p->where, 0); if (p->mode & MNT_CHECK_WRITABLE) { if (access(p->where, W_OK) < 0) { r = -errno; (void) umount2(p->where, UMOUNT_NOFOLLOW); (void) rmdir(p->where); log_full_errno(priority, r, "Mount point %s not writable after mounting, undoing: %m", p->where); return (p->mode & MNT_FATAL) ? r : 0; } } return 1; } static int mount_points_setup(size_t n, bool loaded_policy) { int ret = 0, r; assert(n <= ELEMENTSOF(mount_table)); FOREACH_ARRAY(mp, mount_table, n) { r = mount_one(mp, loaded_policy); if (r != 0 && ret >= 0) ret = r; } return ret; } int mount_setup_early(void) { /* Do a minimal mount of /proc and friends to enable the most basic stuff, such as SELinux */ return mount_points_setup(N_EARLY_MOUNT, /* loaded_policy= */ false); } static const char *join_with(const char *controller) { static const char* const pairs[] = { "cpu", "cpuacct", "net_cls", "net_prio", NULL }; assert(controller); /* This will lookup which controller to mount another controller with. Input is a controller name, and output * is the other controller name. The function works both ways: you can input one and get the other, and input * the other to get the one. */ STRV_FOREACH_PAIR(x, y, pairs) { if (streq(controller, *x)) return *y; if (streq(controller, *y)) return *x; } return NULL; } static int symlink_controller(const char *target, const char *alias) { const char *a; int r; assert(target); assert(alias); a = strjoina("/sys/fs/cgroup/", alias); r = symlink_idempotent(target, a, false); if (r < 0) return log_error_errno(r, "Failed to create symlink %s: %m", a); #if HAVE_SMACK_RUN_LABEL const char *p; p = strjoina("/sys/fs/cgroup/", target); r = mac_smack_copy(a, p); if (r < 0 && !ERRNO_IS_NOT_SUPPORTED(r)) return log_error_errno(r, "Failed to copy smack label from %s to %s: %m", p, a); #endif return 0; } int mount_cgroup_controllers(void) { _cleanup_set_free_ Set *controllers = NULL; int r; if (!cg_is_legacy_wanted()) return 0; /* Mount all available cgroup controllers that are built into the kernel. */ r = cg_kernel_controllers(&controllers); if (r < 0) return log_error_errno(r, "Failed to enumerate cgroup controllers: %m"); for (;;) { _cleanup_free_ char *options = NULL, *controller = NULL, *where = NULL; const char *other_controller; MountPoint p = { .what = "cgroup", .type = "cgroup", .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV, .mode = MNT_IN_CONTAINER, }; controller = set_steal_first(controllers); if (!controller) break; /* Check if we shall mount this together with another controller */ other_controller = join_with(controller); if (other_controller) { _cleanup_free_ char *c = NULL; /* Check if the other controller is actually available in the kernel too */ c = set_remove(controllers, other_controller); if (c) { /* Join the two controllers into one string, and maintain a stable ordering */ if (strcmp(controller, other_controller) < 0) options = strjoin(controller, ",", other_controller); else options = strjoin(other_controller, ",", controller); if (!options) return log_oom(); } } /* The simple case, where there's only one controller to mount together */ if (!options) options = TAKE_PTR(controller); where = path_join("/sys/fs/cgroup", options); if (!where) return log_oom(); p.where = where; p.options = options; r = mount_one(&p, true); if (r < 0) return r; /* Create symlinks from the individual controller names, in case we have a joined mount */ if (controller) (void) symlink_controller(options, controller); if (other_controller) (void) symlink_controller(options, other_controller); } /* Now that we mounted everything, let's make the tmpfs the cgroup file systems are mounted into read-only. */ (void) mount_nofollow("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=0755" TMPFS_LIMITS_SYS_FS_CGROUP); return 0; } #if HAVE_SELINUX || ENABLE_SMACK static int relabel_cb( RecurseDirEvent event, const char *path, int dir_fd, int inode_fd, const struct dirent *de, const struct statx *sx, void *userdata) { switch (event) { case RECURSE_DIR_LEAVE: case RECURSE_DIR_SKIP_MOUNT: /* If we already saw this dirent when entering it or this is a dirent that on a different * mount, don't relabel it. */ return RECURSE_DIR_CONTINUE; case RECURSE_DIR_ENTER: /* /run/initramfs/ + /run/nextroot/ are static data and big, no need to dynamically relabel * its contents at boot... */ if (PATH_STARTSWITH_SET(path, "/run/initramfs", "/run/nextroot")) return RECURSE_DIR_SKIP_ENTRY; _fallthrough_; default: /* Otherwise, label it, even if we had trouble stat()ing it and similar. SELinux can figure this out */ (void) label_fix(path, 0); return RECURSE_DIR_CONTINUE; } } static int relabel_tree(const char *path) { int r; r = recurse_dir_at(AT_FDCWD, path, 0, UINT_MAX, RECURSE_DIR_ENSURE_TYPE|RECURSE_DIR_SAME_MOUNT, relabel_cb, NULL); if (r < 0) log_debug_errno(r, "Failed to recursively relabel '%s': %m", path); return r; } static int relabel_cgroup_filesystems(void) { int r; struct statfs st; r = cg_all_unified(); if (r == 0) { /* Temporarily remount the root cgroup filesystem to give it a proper label. Do this only when the filesystem has been already populated by a previous instance of systemd running from initrd. Otherwise don't remount anything and leave the filesystem read-write for the cgroup filesystems to be mounted inside. */ if (statfs("/sys/fs/cgroup", &st) < 0) return log_error_errno(errno, "Failed to determine mount flags for /sys/fs/cgroup: %m"); if (st.f_flags & ST_RDONLY) (void) mount_nofollow(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT, NULL); (void) label_fix("/sys/fs/cgroup", 0); (void) relabel_tree("/sys/fs/cgroup"); if (st.f_flags & ST_RDONLY) (void) mount_nofollow(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT|MS_RDONLY, NULL); } else if (r < 0) return log_error_errno(r, "Failed to determine whether we are in all unified mode: %m"); return 0; } static int relabel_extra(void) { _cleanup_strv_free_ char **files = NULL; int r, c = 0; /* Support for relabelling additional files or directories after loading the policy. For this, code in the * initrd simply has to drop in *.relabel files into /run/systemd/relabel-extra.d/. We'll read all such files * expecting one absolute path by line and will relabel each (and everyone below that in case the path refers * to a directory). These drop-in files are supposed to be absolutely minimal, and do not understand comments * and such. After the operation succeeded the files are removed, and the drop-in directory as well, if * possible. */ r = conf_files_list(&files, ".relabel", NULL, CONF_FILES_FILTER_MASKED | CONF_FILES_REGULAR, "/run/systemd/relabel-extra.d/"); if (r < 0) return log_error_errno(r, "Failed to enumerate /run/systemd/relabel-extra.d/, ignoring: %m"); STRV_FOREACH(file, files) { _cleanup_fclose_ FILE *f = NULL; f = fopen(*file, "re"); if (!f) { log_warning_errno(errno, "Failed to open %s, ignoring: %m", *file); continue; } for (;;) { _cleanup_free_ char *line = NULL; r = read_line(f, LONG_LINE_MAX, &line); if (r < 0) { log_warning_errno(r, "Failed to read %s, ignoring: %m", *file); break; } if (r == 0) /* EOF */ break; path_simplify(line); if (!path_is_normalized(line)) { log_warning("Path to relabel is not normalized, ignoring: %s", line); continue; } if (!path_is_absolute(line)) { log_warning("Path to relabel is not absolute, ignoring: %s", line); continue; } log_debug("Relabelling additional file/directory '%s'.", line); (void) label_fix(line, 0); (void) relabel_tree(line); c++; } if (unlink(*file) < 0) log_warning_errno(errno, "Failed to remove %s, ignoring: %m", *file); } /* Remove when we complete things. */ if (rmdir("/run/systemd/relabel-extra.d") < 0 && errno != ENOENT) log_warning_errno(errno, "Failed to remove /run/systemd/relabel-extra.d/ directory: %m"); return c; } #endif int mount_setup(bool loaded_policy, bool leave_propagation) { int r; r = mount_points_setup(ELEMENTSOF(mount_table), loaded_policy); if (r < 0) return r; #if HAVE_SELINUX || ENABLE_SMACK /* Nodes in devtmpfs and /run need to be manually updated for * the appropriate labels, after mounting. The other virtual * API file systems like /sys and /proc do not need that, they * use the same label for all their files. */ if (loaded_policy) { usec_t before_relabel, after_relabel; int n_extra; before_relabel = now(CLOCK_MONOTONIC); FOREACH_STRING(i, "/dev", "/dev/shm", "/run") (void) relabel_tree(i); (void) relabel_cgroup_filesystems(); n_extra = relabel_extra(); after_relabel = now(CLOCK_MONOTONIC); log_info("Relabeled /dev, /dev/shm, /run, /sys/fs/cgroup%s in %s.", n_extra > 0 ? ", additional files" : "", FORMAT_TIMESPAN(after_relabel - before_relabel, 0)); } #endif /* Create a few default symlinks, which are normally created * by udevd, but some scripts might need them before we start * udevd. */ dev_setup(NULL, UID_INVALID, GID_INVALID); /* Mark the root directory as shared in regards to mount propagation. The kernel defaults to "private", but we * think it makes more sense to have a default of "shared" so that nspawn and the container tools work out of * the box. If specific setups need other settings they can reset the propagation mode to private if * needed. Note that we set this only when we are invoked directly by the kernel. If we are invoked by a * container manager we assume the container manager knows what it is doing (for example, because it set up * some directories with different propagation modes). */ if (detect_container() <= 0 && !leave_propagation) if (mount(NULL, "/", NULL, MS_REC|MS_SHARED, NULL) < 0) log_warning_errno(errno, "Failed to set up the root directory for shared mount propagation: %m"); /* Create a few directories we always want around, Note that sd_booted() checks for /run/systemd/system, so * this mkdir really needs to stay for good, otherwise software that copied sd-daemon.c into their sources will * misdetect systemd. */ (void) mkdir_label("/run/systemd", 0755); (void) mkdir_label("/run/systemd/system", 0755); /* Make sure there's always a place where sandboxed environments can mount root file systems they are * about to move into, even when unprivileged, without having to create a temporary one in /tmp/ * (which they then have to keep track of and clean) */ (void) mkdir_label("/run/systemd/mount-rootfs", 0555); /* Make sure we have a mount point to hide in sandboxes */ (void) mkdir_label("/run/credentials", 0755); /* Also create /run/systemd/inaccessible nodes, so that we always have something to mount * inaccessible nodes from. If we run in a container the host might have created these for us already * in /run/host/inaccessible/. Use those if we can, since that way we likely get access to block/char * device nodes that are inaccessible, and if userns is used to nodes that are on mounts owned by a * userns outside the container and thus nicely read-only and not remountable. */ if (access("/run/host/inaccessible/", F_OK) < 0) { if (errno != ENOENT) log_debug_errno(errno, "Failed to check if /run/host/inaccessible exists, ignoring: %m"); (void) make_inaccessible_nodes("/run/systemd", UID_INVALID, GID_INVALID); } else (void) symlink("../host/inaccessible", "/run/systemd/inaccessible"); return 0; }