/* SPDX-License-Identifier: LGPL-2.1+ */ /*** This file is part of systemd. Copyright 2010 Lennart Poettering ***/ #include #include #include #include //#include #include #include "alloc-util.h" //#include "bus-util.h" #include "cgroup-util.h" //#include "dev-setup.h" //#include "efivars.h" //#include "fileio.h" #include "fs-util.h" #include "label.h" //#include "log.h" #include "macro.h" //#include "missing.h" #include "mkdir.h" #include "mount-setup.h" #include "mount-util.h" #include "path-util.h" //#include "set.h" //#include "smack-util.h" //#include "strv.h" #include "user-util.h" //#include "util.h" #include "virt.h" /// Additional includes needed by elogind #include "string-util.h" typedef enum MountMode { MNT_NONE = 0, MNT_FATAL = 1 << 0, MNT_IN_CONTAINER = 1 << 1, MNT_CHECK_WRITABLE = 1 << 2, } 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 const MountPoint mount_table[] = { #if 0 /// UNNEEDED by elogind { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "devtmpfs", "/dev", "devtmpfs", "mode=755", 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=1777,smackfsroot=*", MS_NOSUID|MS_NODEV|MS_STRICTATIME, mac_smack_use, MNT_FATAL }, #endif { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, NULL, MNT_FATAL|MNT_IN_CONTAINER }, { "devpts", "/dev/pts", "devpts", "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, NULL, MNT_IN_CONTAINER }, #if ENABLE_SMACK { "tmpfs", "/run", "tmpfs", "mode=755,smackfsroot=*", MS_NOSUID|MS_NODEV|MS_STRICTATIME, mac_smack_use, MNT_FATAL }, #endif { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, NULL, MNT_FATAL|MNT_IN_CONTAINER }, #endif // 0 { "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=755", 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 }, #if 0 /// UNNEEDED by elogind { "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 }, { "pstore", "/sys/fs/pstore", "pstore", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_NONE }, #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=700", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL, MNT_NONE, }, #else { "cgroup", "/sys/fs/cgroup/elogind", "cgroup", "none,name=elogind,release_agent="SYSTEMD_CGROUP_AGENT_PATH",xattr", MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_legacy_wanted, MNT_IN_CONTAINER }, { "cgroup", "/sys/fs/cgroup/elogind", "cgroup", "none,name=elogind,release_agent="SYSTEMD_CGROUP_AGENT_PATH, MS_NOSUID|MS_NOEXEC|MS_NODEV, cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER }, #endif // 0 }; #if 0 /// UNNEEDED by elogind /* 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 */ static const char ignore_paths[] = /* SELinux file systems */ "/sys/fs/selinux\0" /* Container bind mounts */ "/proc/sys\0" "/dev/console\0" "/proc/kmsg\0"; bool mount_point_is_api(const char *path) { unsigned i; /* Checks if this mount point is considered "API", and hence * should be ignored */ for (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) { const char *i; NULSTR_FOREACH(i, ignore_paths) if (path_equal(path, i)) return true; return false; } #endif // 0 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 (mount(p->what, p->where, p->type, p->flags, p->options) < 0) { log_full_errno(priority, errno, "Failed to mount %s at %s: %m", p->type, p->where); return (p->mode & MNT_FATAL) ? -errno : 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) umount(p->where); (void) rmdir(p->where); log_full_errno(priority, r, "Mount point %s not writable after mounting: %m", p->where); return (p->mode & MNT_FATAL) ? r : 0; } } return 1; } static int mount_points_setup(unsigned n, bool loaded_policy) { unsigned i; int r = 0; for (i = 0; i < n; i ++) { int j; j = mount_one(mount_table + i, loaded_policy); if (j != 0 && r >= 0) r = j; } return r; } #if 0 /// UNNEEDED by elogind int mount_setup_early(void) { assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table)); /* Do a minimal mount of /proc and friends to enable the most * basic stuff, such as SELinux */ return mount_points_setup(N_EARLY_MOUNT, false); } int mount_cgroup_controllers(char ***join_controllers) { _cleanup_set_free_free_ Set *controllers = NULL; bool has_argument = !!join_controllers; int r; if (!cg_is_legacy_wanted()) return 0; /* Mount all available cgroup controllers that are built into the kernel. */ if (!has_argument) /* The defaults: * mount "cpu" + "cpuacct" together, and "net_cls" + "net_prio". * * We'd like to add "cpuset" to the mix, but "cpuset" doesn't really * work for groups with no initialized attributes. */ join_controllers = (char**[]) { STRV_MAKE("cpu", "cpuacct"), STRV_MAKE("net_cls", "net_prio"), NULL, }; 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; MountPoint p = { .what = "cgroup", .type = "cgroup", .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV, .mode = MNT_IN_CONTAINER, }; char ***k = NULL; controller = set_steal_first(controllers); if (!controller) break; for (k = join_controllers; *k; k++) if (strv_find(*k, controller)) break; if (*k) { char **i, **j; for (i = *k, j = *k; *i; i++) { if (!streq(*i, controller)) { _cleanup_free_ char *t; t = set_remove(controllers, *i); if (!t) { if (has_argument) free(*i); continue; } } *(j++) = *i; } *j = NULL; options = strv_join(*k, ","); if (!options) return log_oom(); } else options = TAKE_PTR(controller); where = strappend("/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; if (r > 0 && *k) { char **i; for (i = *k; *i; i++) { _cleanup_free_ char *t = NULL; t = strappend("/sys/fs/cgroup/", *i); if (!t) return log_oom(); r = symlink(options, t); if (r >= 0) { #ifdef SMACK_RUN_LABEL _cleanup_free_ char *src; src = strappend("/sys/fs/cgroup/", options); if (!src) return log_oom(); r = mac_smack_copy(t, src); if (r < 0 && r != -EOPNOTSUPP) return log_error_errno(r, "Failed to copy smack label from %s to %s: %m", src, t); #endif } else if (errno != EEXIST) return log_error_errno(errno, "Failed to create symlink %s: %m", t); } } } /* Now that we mounted everything, let's make the tmpfs the * cgroup file systems are mounted into read-only. */ (void) mount("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755"); return 0; } #if HAVE_SELINUX || ENABLE_SMACK static int nftw_cb( const char *fpath, const struct stat *sb, int tflag, struct FTW *ftwbuf) { /* No need to label /dev twice in a row... */ if (_unlikely_(ftwbuf->level == 0)) return FTW_CONTINUE; (void) label_fix(fpath, 0); /* /run/initramfs is static data and big, no need to * dynamically relabel its contents at boot... */ if (_unlikely_(ftwbuf->level == 1 && tflag == FTW_D && streq(fpath, "/run/initramfs"))) return FTW_SKIP_SUBTREE; return FTW_CONTINUE; }; 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(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT, NULL); (void) label_fix("/sys/fs/cgroup", 0); (void) nftw("/sys/fs/cgroup", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); if (st.f_flags & ST_RDONLY) (void) mount(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; } #endif #endif // 0 int mount_setup(bool loaded_policy) { int r = 0; r = mount_points_setup(ELEMENTSOF(mount_table), loaded_policy); if (r < 0) return r; #if 0 /// elogind does not control /, /dev, /run and /run/systemd/* are setup elsewhere. #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; char timespan[FORMAT_TIMESPAN_MAX]; before_relabel = now(CLOCK_MONOTONIC); (void) nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); (void) nftw("/dev/shm", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); (void) nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); r = relabel_cgroup_filesystems(); if (r < 0) return r; after_relabel = now(CLOCK_MONOTONIC); log_info("Relabelled /dev, /run and /sys/fs/cgroup in %s.", format_timespan(timespan, sizeof(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) 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"); #endif // 0 /* 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); #if 0 /// Yeah, but elogind is not used with systemd, so this directory would be toxic. (void) mkdir_label("/run/systemd/system", 0755); #endif // 0 /* Set up inaccessible (and empty) file nodes of all types */ (void) mkdir_label("/run/systemd/inaccessible", 0000); (void) mknod("/run/systemd/inaccessible/reg", S_IFREG | 0000, 0); (void) mkdir_label("/run/systemd/inaccessible/dir", 0000); (void) mkfifo("/run/systemd/inaccessible/fifo", 0000); (void) mknod("/run/systemd/inaccessible/sock", S_IFSOCK | 0000, 0); /* The following two are likely to fail if we lack the privs for it (for example in an userns environment, if * CAP_SYS_MKNOD is missing, or if a device node policy prohibit major/minor of 0 device nodes to be * created). But that's entirely fine. Consumers of these files should carry fallback to use a different node * then, for example /run/systemd/inaccessible/sock, which is close enough in behaviour and semantics for most * uses. */ (void) mknod("/run/systemd/inaccessible/chr", S_IFCHR | 0000, makedev(0, 0)); (void) mknod("/run/systemd/inaccessible/blk", S_IFBLK | 0000, makedev(0, 0)); return 0; }