/* SPDX-License-Identifier: LGPL-2.1+ */ #include #include #include #include #include #include #include #include "alloc-util.h" #include "extract-word.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "hashmap.h" #include "libmount-util.h" #include "mount-util.h" #include "mountpoint-util.h" #include "parse-util.h" #include "path-util.h" #include "set.h" #include "stdio-util.h" #include "string-util.h" #include "strv.h" int umount_recursive(const char *prefix, int flags) { int n = 0, r; bool again; /* Try to umount everything recursively below a * directory. Also, take care of stacked mounts, and keep * unmounting them until they are gone. */ do { _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL; _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL; again = false; r = libmount_parse("/proc/self/mountinfo", NULL, &table, &iter); if (r < 0) return log_debug_errno(r, "Failed to parse /proc/self/mountinfo: %m"); for (;;) { struct libmnt_fs *fs; const char *path; r = mnt_table_next_fs(table, iter, &fs); if (r == 1) break; if (r < 0) return log_debug_errno(r, "Failed to get next entry from /proc/self/mountinfo: %m"); path = mnt_fs_get_target(fs); if (!path) continue; if (!path_startswith(path, prefix)) continue; if (umount2(path, flags) < 0) { r = log_debug_errno(errno, "Failed to umount %s: %m", path); continue; } log_debug("Successfully unmounted %s", path); again = true; n++; break; } } while (again); return n; } /* Get the mount flags for the mountpoint at "path" from "table" */ static int get_mount_flags(const char *path, unsigned long *flags, struct libmnt_table *table) { struct statvfs buf = {}; struct libmnt_fs *fs = NULL; const char *opts = NULL; int r = 0; fs = mnt_table_find_target(table, path, MNT_ITER_FORWARD); if (!fs) { log_warning("Could not find '%s' in mount table", path); goto fallback; } opts = mnt_fs_get_vfs_options(fs); r = mnt_optstr_get_flags(opts, flags, mnt_get_builtin_optmap(MNT_LINUX_MAP)); if (r != 0) { log_warning_errno(r, "Could not get flags for '%s': %m", path); goto fallback; } /* relatime is default and trying to set it in an unprivileged container causes EPERM */ *flags &= ~MS_RELATIME; return 0; fallback: if (statvfs(path, &buf) < 0) return -errno; *flags = buf.f_flag; return 0; } /* Use this function only if you do not have direct access to /proc/self/mountinfo but the caller can open it * for you. This is the case when /proc is masked or not mounted. Otherwise, use bind_remount_recursive. */ int bind_remount_recursive_with_mountinfo( const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **blacklist, FILE *proc_self_mountinfo) { _cleanup_set_free_free_ Set *done = NULL; _cleanup_free_ char *cleaned = NULL; int r; assert(proc_self_mountinfo); /* Recursively remount a directory (and all its submounts) read-only or read-write. If the directory is already * mounted, we reuse the mount and simply mark it MS_BIND|MS_RDONLY (or remove the MS_RDONLY for read-write * operation). If it isn't we first make it one. Afterwards we apply MS_BIND|MS_RDONLY (or remove MS_RDONLY) to * all submounts we can access, too. When mounts are stacked on the same mount point we only care for each * individual "top-level" mount on each point, as we cannot influence/access the underlying mounts anyway. We * do not have any effect on future submounts that might get propagated, they migt be writable. This includes * future submounts that have been triggered via autofs. * * If the "blacklist" parameter is specified it may contain a list of subtrees to exclude from the * remount operation. Note that we'll ignore the blacklist for the top-level path. */ cleaned = strdup(prefix); if (!cleaned) return -ENOMEM; path_simplify(cleaned, false); done = set_new(&path_hash_ops); if (!done) return -ENOMEM; for (;;) { _cleanup_set_free_free_ Set *todo = NULL; _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL; _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL; bool top_autofs = false; char *x; unsigned long orig_flags; todo = set_new(&path_hash_ops); if (!todo) return -ENOMEM; rewind(proc_self_mountinfo); r = libmount_parse("/proc/self/mountinfo", proc_self_mountinfo, &table, &iter); if (r < 0) return log_debug_errno(r, "Failed to parse /proc/self/mountinfo: %m"); for (;;) { struct libmnt_fs *fs; const char *path, *type; r = mnt_table_next_fs(table, iter, &fs); if (r == 1) break; if (r < 0) return log_debug_errno(r, "Failed to get next entry from /proc/self/mountinfo: %m"); path = mnt_fs_get_target(fs); type = mnt_fs_get_fstype(fs); if (!path || !type) continue; if (!path_startswith(path, cleaned)) continue; /* Ignore this mount if it is blacklisted, but only if it isn't the top-level mount * we shall operate on. */ if (!path_equal(path, cleaned)) { bool blacklisted = false; char **i; STRV_FOREACH(i, blacklist) { if (path_equal(*i, cleaned)) continue; if (!path_startswith(*i, cleaned)) continue; if (path_startswith(path, *i)) { blacklisted = true; log_debug("Not remounting %s blacklisted by %s, called for %s", path, *i, cleaned); break; } } if (blacklisted) continue; } /* Let's ignore autofs mounts. If they aren't * triggered yet, we want to avoid triggering * them, as we don't make any guarantees for * future submounts anyway. If they are * already triggered, then we will find * another entry for this. */ if (streq(type, "autofs")) { top_autofs = top_autofs || path_equal(path, cleaned); continue; } if (!set_contains(done, path)) { r = set_put_strdup(todo, path); if (r < 0) return r; } } /* If we have no submounts to process anymore and if * the root is either already done, or an autofs, we * are done */ if (set_isempty(todo) && (top_autofs || set_contains(done, cleaned))) return 0; if (!set_contains(done, cleaned) && !set_contains(todo, cleaned)) { /* The prefix directory itself is not yet a mount, make it one. */ if (mount(cleaned, cleaned, NULL, MS_BIND|MS_REC, NULL) < 0) return -errno; orig_flags = 0; (void) get_mount_flags(cleaned, &orig_flags, table); orig_flags &= ~MS_RDONLY; if (mount(NULL, cleaned, NULL, (orig_flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags, NULL) < 0) return -errno; log_debug("Made top-level directory %s a mount point.", prefix); r = set_put_strdup(done, cleaned); if (r < 0) return r; } while ((x = set_steal_first(todo))) { r = set_consume(done, x); if (IN_SET(r, 0, -EEXIST)) continue; if (r < 0) return r; /* Deal with mount points that are obstructed by a later mount */ r = path_is_mount_point(x, NULL, 0); if (IN_SET(r, 0, -ENOENT)) continue; if (IN_SET(r, -EACCES, -EPERM)) { /* Even if root user invoke this, submounts under private FUSE or NFS mount points * may not be acceessed. E.g., * * $ bindfs --no-allow-other ~/mnt/mnt ~/mnt/mnt * $ bindfs --no-allow-other ~/mnt ~/mnt * * Then, root user cannot access the mount point ~/mnt/mnt. * In such cases, the submounts are ignored, as we have no way to manage them. */ log_debug_errno(r, "Failed to determine '%s' is mount point or not, ignoring: %m", x); continue; } if (r < 0) return r; /* Try to reuse the original flag set */ orig_flags = 0; (void) get_mount_flags(x, &orig_flags, table); orig_flags &= ~MS_RDONLY; if (mount(NULL, x, NULL, (orig_flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags, NULL) < 0) return -errno; log_debug("Remounted %s read-only.", x); } } } int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **blacklist) { _cleanup_fclose_ FILE *proc_self_mountinfo = NULL; int r; r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo); if (r < 0) return r; return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, blacklist, proc_self_mountinfo); } int mount_move_root(const char *path) { assert(path); if (chdir(path) < 0) return -errno; if (mount(path, "/", NULL, MS_MOVE, NULL) < 0) return -errno; if (chroot(".") < 0) return -errno; if (chdir("/") < 0) return -errno; return 0; } int repeat_unmount(const char *path, int flags) { bool done = false; assert(path); /* If there are multiple mounts on a mount point, this * removes them all */ for (;;) { if (umount2(path, flags) < 0) { if (errno == EINVAL) return done; return -errno; } done = true; } } const char* mode_to_inaccessible_node(mode_t mode) { /* This function maps a node type to a corresponding inaccessible file node. These nodes are created during * early boot by PID 1. In some cases we lacked the privs to create the character and block devices (maybe * because we run in an userns environment, or miss CAP_SYS_MKNOD, or run with a devices policy that excludes * device nodes with major and minor of 0), but that's fine, in that case we use an AF_UNIX file node instead, * which is not the same, but close enough for most uses. And most importantly, the kernel allows bind mounts * from socket nodes to any non-directory file nodes, and that's the most important thing that matters. */ switch(mode & S_IFMT) { case S_IFREG: return "/run/systemd/inaccessible/reg"; case S_IFDIR: return "/run/systemd/inaccessible/dir"; case S_IFCHR: if (access("/run/systemd/inaccessible/chr", F_OK) == 0) return "/run/systemd/inaccessible/chr"; return "/run/systemd/inaccessible/sock"; case S_IFBLK: if (access("/run/systemd/inaccessible/blk", F_OK) == 0) return "/run/systemd/inaccessible/blk"; return "/run/systemd/inaccessible/sock"; case S_IFIFO: return "/run/systemd/inaccessible/fifo"; case S_IFSOCK: return "/run/systemd/inaccessible/sock"; } return NULL; } #define FLAG(name) (flags & name ? STRINGIFY(name) "|" : "") static char* mount_flags_to_string(long unsigned flags) { char *x; _cleanup_free_ char *y = NULL; long unsigned overflow; overflow = flags & ~(MS_RDONLY | MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_SYNCHRONOUS | MS_REMOUNT | MS_MANDLOCK | MS_DIRSYNC | MS_NOATIME | MS_NODIRATIME | MS_BIND | MS_MOVE | MS_REC | MS_SILENT | MS_POSIXACL | MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED | MS_RELATIME | MS_KERNMOUNT | MS_I_VERSION | MS_STRICTATIME | MS_LAZYTIME); if (flags == 0 || overflow != 0) if (asprintf(&y, "%lx", overflow) < 0) return NULL; x = strjoin(FLAG(MS_RDONLY), FLAG(MS_NOSUID), FLAG(MS_NODEV), FLAG(MS_NOEXEC), FLAG(MS_SYNCHRONOUS), FLAG(MS_REMOUNT), FLAG(MS_MANDLOCK), FLAG(MS_DIRSYNC), FLAG(MS_NOATIME), FLAG(MS_NODIRATIME), FLAG(MS_BIND), FLAG(MS_MOVE), FLAG(MS_REC), FLAG(MS_SILENT), FLAG(MS_POSIXACL), FLAG(MS_UNBINDABLE), FLAG(MS_PRIVATE), FLAG(MS_SLAVE), FLAG(MS_SHARED), FLAG(MS_RELATIME), FLAG(MS_KERNMOUNT), FLAG(MS_I_VERSION), FLAG(MS_STRICTATIME), FLAG(MS_LAZYTIME), y); if (!x) return NULL; if (!y) x[strlen(x) - 1] = '\0'; /* truncate the last | */ return x; } int mount_verbose( int error_log_level, const char *what, const char *where, const char *type, unsigned long flags, const char *options) { _cleanup_free_ char *fl = NULL, *o = NULL; unsigned long f; int r; r = mount_option_mangle(options, flags, &f, &o); if (r < 0) return log_full_errno(error_log_level, r, "Failed to mangle mount options %s: %m", strempty(options)); fl = mount_flags_to_string(f); if ((f & MS_REMOUNT) && !what && !type) log_debug("Remounting %s (%s \"%s\")...", where, strnull(fl), strempty(o)); else if (!what && !type) log_debug("Mounting %s (%s \"%s\")...", where, strnull(fl), strempty(o)); else if ((f & MS_BIND) && !type) log_debug("Bind-mounting %s on %s (%s \"%s\")...", what, where, strnull(fl), strempty(o)); else if (f & MS_MOVE) log_debug("Moving mount %s → %s (%s \"%s\")...", what, where, strnull(fl), strempty(o)); else log_debug("Mounting %s on %s (%s \"%s\")...", strna(type), where, strnull(fl), strempty(o)); if (mount(what, where, type, f, o) < 0) return log_full_errno(error_log_level, errno, "Failed to mount %s (type %s) on %s (%s \"%s\"): %m", strna(what), strna(type), where, strnull(fl), strempty(o)); return 0; } int umount_verbose(const char *what) { log_debug("Umounting %s...", what); if (umount(what) < 0) return log_error_errno(errno, "Failed to unmount %s: %m", what); return 0; } int mount_option_mangle( const char *options, unsigned long mount_flags, unsigned long *ret_mount_flags, char **ret_remaining_options) { const struct libmnt_optmap *map; _cleanup_free_ char *ret = NULL; const char *p; int r; /* This extracts mount flags from the mount options, and store * non-mount-flag options to '*ret_remaining_options'. * E.g., * "rw,nosuid,nodev,relatime,size=1630748k,mode=700,uid=1000,gid=1000" * is split to MS_NOSUID|MS_NODEV|MS_RELATIME and * "size=1630748k,mode=700,uid=1000,gid=1000". * See more examples in test-mount-utils.c. * * Note that if 'options' does not contain any non-mount-flag options, * then '*ret_remaining_options' is set to NULL instead of empty string. * Note that this does not check validity of options stored in * '*ret_remaining_options'. * Note that if 'options' is NULL, then this just copies 'mount_flags' * to '*ret_mount_flags'. */ assert(ret_mount_flags); assert(ret_remaining_options); map = mnt_get_builtin_optmap(MNT_LINUX_MAP); if (!map) return -EINVAL; p = options; for (;;) { _cleanup_free_ char *word = NULL; const struct libmnt_optmap *ent; r = extract_first_word(&p, &word, ",", EXTRACT_UNQUOTE); if (r < 0) return r; if (r == 0) break; for (ent = map; ent->name; ent++) { /* All entries in MNT_LINUX_MAP do not take any argument. * Thus, ent->name does not contain "=" or "[=]". */ if (!streq(word, ent->name)) continue; if (!(ent->mask & MNT_INVERT)) mount_flags |= ent->id; else if (mount_flags & ent->id) mount_flags ^= ent->id; break; } /* If 'word' is not a mount flag, then store it in '*ret_remaining_options'. */ if (!ent->name && !strextend_with_separator(&ret, ",", word, NULL)) return -ENOMEM; } *ret_mount_flags = mount_flags; *ret_remaining_options = TAKE_PTR(ret); return 0; }