/* SPDX-License-Identifier: LGPL-2.1+ */ #include #include #include #include #include #include #include #include /* Include later */ #include #include "alloc-util.h" #include "def.h" #include "escape.h" #include "extract-word.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "hashmap.h" #include "mount-util.h" #include "parse-util.h" #include "path-util.h" #include "set.h" #include "stdio-util.h" #include "string-util.h" #include "strv.h" /* This is the original MAX_HANDLE_SZ definition from the kernel, when the API was introduced. We use that in place of * any more currently defined value to future-proof things: if the size is increased in the API headers, and our code * is recompiled then it would cease working on old kernels, as those refuse any sizes larger than this value with * EINVAL right-away. Hence, let's disconnect ourselves from any such API changes, and stick to the original definition * from when it was introduced. We use it as a start value only anyway (see below), and hence should be able to deal * with large file handles anyway. */ #define ORIGINAL_MAX_HANDLE_SZ 128 int name_to_handle_at_loop( int fd, const char *path, struct file_handle **ret_handle, int *ret_mnt_id, int flags) { _cleanup_free_ struct file_handle *h = NULL; size_t n = ORIGINAL_MAX_HANDLE_SZ; /* We need to invoke name_to_handle_at() in a loop, given that it might return EOVERFLOW when the specified * buffer is too small. Note that in contrast to what the docs might suggest, MAX_HANDLE_SZ is only good as a * start value, it is not an upper bound on the buffer size required. * * This improves on raw name_to_handle_at() also in one other regard: ret_handle and ret_mnt_id can be passed * as NULL if there's no interest in either. */ for (;;) { int mnt_id = -1; h = malloc0(offsetof(struct file_handle, f_handle) + n); if (!h) return -ENOMEM; h->handle_bytes = n; if (name_to_handle_at(fd, path, h, &mnt_id, flags) >= 0) { if (ret_handle) *ret_handle = TAKE_PTR(h); if (ret_mnt_id) *ret_mnt_id = mnt_id; return 0; } if (errno != EOVERFLOW) return -errno; if (!ret_handle && ret_mnt_id && mnt_id >= 0) { /* As it appears, name_to_handle_at() fills in mnt_id even when it returns EOVERFLOW when the * buffer is too small, but that's undocumented. Hence, let's make use of this if it appears to * be filled in, and the caller was interested in only the mount ID an nothing else. */ *ret_mnt_id = mnt_id; return 0; } /* If name_to_handle_at() didn't increase the byte size, then this EOVERFLOW is caused by something * else (apparently EOVERFLOW is returned for untriggered nfs4 mounts sometimes), not by the too small * buffer. In that case propagate EOVERFLOW */ if (h->handle_bytes <= n) return -EOVERFLOW; /* The buffer was too small. Size the new buffer by what name_to_handle_at() returned. */ n = h->handle_bytes; if (offsetof(struct file_handle, f_handle) + n < n) /* check for addition overflow */ return -EOVERFLOW; h = mfree(h); } } static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id) { char path[STRLEN("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)]; _cleanup_free_ char *fdinfo = NULL; _cleanup_close_ int subfd = -1; char *p; int r; if ((flags & AT_EMPTY_PATH) && isempty(filename)) xsprintf(path, "/proc/self/fdinfo/%i", fd); else { subfd = openat(fd, filename, O_CLOEXEC|O_PATH); if (subfd < 0) return -errno; xsprintf(path, "/proc/self/fdinfo/%i", subfd); } r = read_full_file(path, &fdinfo, NULL); if (r == -ENOENT) /* The fdinfo directory is a relatively new addition */ return -EOPNOTSUPP; if (r < 0) return r; p = startswith(fdinfo, "mnt_id:"); if (!p) { p = strstr(fdinfo, "\nmnt_id:"); if (!p) /* The mnt_id field is a relatively new addition */ return -EOPNOTSUPP; p += 8; } p += strspn(p, WHITESPACE); p[strcspn(p, WHITESPACE)] = 0; return safe_atoi(p, mnt_id); } int fd_is_mount_point(int fd, const char *filename, int flags) { _cleanup_free_ struct file_handle *h = NULL, *h_parent = NULL; int mount_id = -1, mount_id_parent = -1; bool nosupp = false, check_st_dev = true; struct stat a, b; int r; assert(fd >= 0); assert(filename); /* First we will try the name_to_handle_at() syscall, which * tells us the mount id and an opaque file "handle". It is * not supported everywhere though (kernel compile-time * option, not all file systems are hooked up). If it works * the mount id is usually good enough to tell us whether * something is a mount point. * * If that didn't work we will try to read the mount id from * /proc/self/fdinfo/. This is almost as good as * name_to_handle_at(), however, does not return the * opaque file handle. The opaque file handle is pretty useful * to detect the root directory, which we should always * consider a mount point. Hence we use this only as * fallback. Exporting the mnt_id in fdinfo is a pretty recent * kernel addition. * * As last fallback we do traditional fstat() based st_dev * comparisons. This is how things were traditionally done, * but unionfs breaks this since it exposes file * systems with a variety of st_dev reported. Also, btrfs * subvolumes have different st_dev, even though they aren't * real mounts of their own. */ r = name_to_handle_at_loop(fd, filename, &h, &mount_id, flags); if (IN_SET(r, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL)) /* This kernel does not support name_to_handle_at() at all (ENOSYS), or the syscall was blocked * (EACCES/EPERM; maybe through seccomp, because we are running inside of a container?), or the mount * point is not triggered yet (EOVERFLOW, think nfs4), or some general name_to_handle_at() flakiness * (EINVAL): fall back to simpler logic. */ goto fallback_fdinfo; else if (r == -EOPNOTSUPP) /* This kernel or file system does not support name_to_handle_at(), hence let's see if the upper fs * supports it (in which case it is a mount point), otherwise fallback to the traditional stat() * logic */ nosupp = true; else if (r < 0) return r; r = name_to_handle_at_loop(fd, "", &h_parent, &mount_id_parent, AT_EMPTY_PATH); if (r == -EOPNOTSUPP) { if (nosupp) /* Neither parent nor child do name_to_handle_at()? We have no choice but to fall back. */ goto fallback_fdinfo; else /* The parent can't do name_to_handle_at() but the directory we are interested in can? If so, * it must be a mount point. */ return 1; } else if (r < 0) return r; /* The parent can do name_to_handle_at() but the * directory we are interested in can't? If so, it * must be a mount point. */ if (nosupp) return 1; /* If the file handle for the directory we are * interested in and its parent are identical, we * assume this is the root directory, which is a mount * point. */ if (h->handle_bytes == h_parent->handle_bytes && h->handle_type == h_parent->handle_type && memcmp(h->f_handle, h_parent->f_handle, h->handle_bytes) == 0) return 1; return mount_id != mount_id_parent; fallback_fdinfo: r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id); if (IN_SET(r, -EOPNOTSUPP, -EACCES, -EPERM)) goto fallback_fstat; if (r < 0) return r; r = fd_fdinfo_mnt_id(fd, "", AT_EMPTY_PATH, &mount_id_parent); if (r < 0) return r; if (mount_id != mount_id_parent) return 1; /* Hmm, so, the mount ids are the same. This leaves one * special case though for the root file system. For that, * let's see if the parent directory has the same inode as we * are interested in. Hence, let's also do fstat() checks now, * too, but avoid the st_dev comparisons, since they aren't * that useful on unionfs mounts. */ check_st_dev = false; fallback_fstat: /* yay for fstatat() taking a different set of flags than the other * _at() above */ if (flags & AT_SYMLINK_FOLLOW) flags &= ~AT_SYMLINK_FOLLOW; else flags |= AT_SYMLINK_NOFOLLOW; if (fstatat(fd, filename, &a, flags) < 0) return -errno; if (fstatat(fd, "", &b, AT_EMPTY_PATH) < 0) return -errno; /* A directory with same device and inode as its parent? Must * be the root directory */ if (a.st_dev == b.st_dev && a.st_ino == b.st_ino) return 1; return check_st_dev && (a.st_dev != b.st_dev); } /* flags can be AT_SYMLINK_FOLLOW or 0 */ int path_is_mount_point(const char *t, const char *root, int flags) { _cleanup_free_ char *canonical = NULL; _cleanup_close_ int fd = -1; int r; assert(t); assert((flags & ~AT_SYMLINK_FOLLOW) == 0); if (path_equal(t, "/")) return 1; /* we need to resolve symlinks manually, we can't just rely on * fd_is_mount_point() to do that for us; if we have a structure like * /bin -> /usr/bin/ and /usr is a mount point, then the parent that we * look at needs to be /usr, not /. */ if (flags & AT_SYMLINK_FOLLOW) { r = chase_symlinks(t, root, CHASE_TRAIL_SLASH, &canonical); if (r < 0) return r; t = canonical; } fd = open_parent(t, O_PATH|O_CLOEXEC, 0); if (fd < 0) return -errno; return fd_is_mount_point(fd, last_path_component(t), flags); } int path_get_mnt_id(const char *path, int *ret) { int r; r = name_to_handle_at_loop(AT_FDCWD, path, NULL, ret, 0); if (IN_SET(r, -EOPNOTSUPP, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL)) /* kernel/fs don't support this, or seccomp blocks access, or untriggered mount, or name_to_handle_at() is flaky */ return fd_fdinfo_mnt_id(AT_FDCWD, path, 0, ret); return r; } int umount_recursive(const char *prefix, int flags) { bool again; int n = 0, r; /* Try to umount everything recursively below a * directory. Also, take care of stacked mounts, and keep * unmounting them until they are gone. */ do { _cleanup_fclose_ FILE *proc_self_mountinfo = NULL; again = false; r = 0; proc_self_mountinfo = fopen("/proc/self/mountinfo", "re"); if (!proc_self_mountinfo) return -errno; (void) __fsetlocking(proc_self_mountinfo, FSETLOCKING_BYCALLER); for (;;) { _cleanup_free_ char *path = NULL, *p = NULL; int k; k = fscanf(proc_self_mountinfo, "%*s " /* (1) mount id */ "%*s " /* (2) parent id */ "%*s " /* (3) major:minor */ "%*s " /* (4) root */ "%ms " /* (5) mount point */ "%*s" /* (6) mount options */ "%*[^-]" /* (7) optional fields */ "- " /* (8) separator */ "%*s " /* (9) file system type */ "%*s" /* (10) mount source */ "%*s" /* (11) mount options 2 */ "%*[^\n]", /* some rubbish at the end */ &path); if (k != 1) { if (k == EOF) break; continue; } r = cunescape(path, UNESCAPE_RELAX, &p); if (r < 0) return r; if (!path_startswith(p, prefix)) continue; if (umount2(p, flags) < 0) { r = log_debug_errno(errno, "Failed to umount %s: %m", p); continue; } log_debug("Successfully unmounted %s", p); again = true; n++; break; } } while (again); return r ? r : n; } static int get_mount_flags(const char *path, unsigned long *flags) { struct statvfs buf; if (statvfs(path, &buf) < 0) return -errno; *flags = buf.f_flag; return 0; } /* Use this function only if do you have direct access to /proc/self/mountinfo * and need the caller to 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, bool ro, 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; bool top_autofs = false; char *x; unsigned long orig_flags; todo = set_new(&path_hash_ops); if (!todo) return -ENOMEM; rewind(proc_self_mountinfo); for (;;) { _cleanup_free_ char *path = NULL, *p = NULL, *type = NULL; int k; k = fscanf(proc_self_mountinfo, "%*s " /* (1) mount id */ "%*s " /* (2) parent id */ "%*s " /* (3) major:minor */ "%*s " /* (4) root */ "%ms " /* (5) mount point */ "%*s" /* (6) mount options (superblock) */ "%*[^-]" /* (7) optional fields */ "- " /* (8) separator */ "%ms " /* (9) file system type */ "%*s" /* (10) mount source */ "%*s" /* (11) mount options (bind mount) */ "%*[^\n]", /* some rubbish at the end */ &path, &type); if (k != 2) { if (k == EOF) break; continue; } r = cunescape(path, UNESCAPE_RELAX, &p); if (r < 0) return r; if (!path_startswith(p, 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(cleaned, p)) { bool blacklisted = false; char **i; STRV_FOREACH(i, blacklist) { if (path_equal(*i, cleaned)) continue; if (!path_startswith(*i, cleaned)) continue; if (path_startswith(p, *i)) { blacklisted = true; log_debug("Not remounting %s blacklisted by %s, called for %s", p, *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(cleaned, p); continue; } if (!set_contains(done, p)) { r = set_consume(todo, p); p = NULL; if (r == -EEXIST) continue; 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); orig_flags &= ~MS_RDONLY; if (mount(NULL, cleaned, NULL, orig_flags|MS_BIND|MS_REMOUNT|(ro ? MS_RDONLY : 0), NULL) < 0) return -errno; log_debug("Made top-level directory %s a mount point.", prefix); x = strdup(cleaned); if (!x) return -ENOMEM; r = set_consume(done, x); 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); orig_flags &= ~MS_RDONLY; if (mount(NULL, x, NULL, orig_flags|MS_BIND|MS_REMOUNT|(ro ? MS_RDONLY : 0), NULL) < 0) return -errno; log_debug("Remounted %s read-only.", x); } } } int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) { _cleanup_fclose_ FILE *proc_self_mountinfo = NULL; proc_self_mountinfo = fopen("/proc/self/mountinfo", "re"); if (!proc_self_mountinfo) return -errno; (void) __fsetlocking(proc_self_mountinfo, FSETLOCKING_BYCALLER); return bind_remount_recursive_with_mountinfo(prefix, ro, 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; } bool fstype_is_network(const char *fstype) { const char *x; x = startswith(fstype, "fuse."); if (x) fstype = x; return STR_IN_SET(fstype, "afs", "cifs", "smbfs", "sshfs", "ncpfs", "ncp", "nfs", "nfs4", "gfs", "gfs2", "glusterfs", "pvfs2", /* OrangeFS */ "ocfs2", "lustre"); } bool fstype_is_api_vfs(const char *fstype) { return STR_IN_SET(fstype, "autofs", "bpf", "cgroup", "cgroup2", "configfs", "cpuset", "debugfs", "devpts", "devtmpfs", "efivarfs", "fusectl", "hugetlbfs", "mqueue", "proc", "pstore", "ramfs", "securityfs", "sysfs", "tmpfs", "tracefs"); } bool fstype_is_ro(const char *fstype) { /* All Linux file systems that are necessarily read-only */ return STR_IN_SET(fstype, "DM_verity_hash", "iso9660", "squashfs"); } bool fstype_can_discard(const char *fstype) { return STR_IN_SET(fstype, "btrfs", "ext4", "vfat", "xfs"); } bool fstype_can_uid_gid(const char *fstype) { /* All file systems that have a uid=/gid= mount option that fixates the owners of all files and directories, * current and future. */ return STR_IN_SET(fstype, "adfs", "fat", "hfs", "hpfs", "iso9660", "msdos", "ntfs", "vfat"); } 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; } const char *mount_propagation_flags_to_string(unsigned long flags) { switch (flags & (MS_SHARED|MS_SLAVE|MS_PRIVATE)) { case 0: return ""; case MS_SHARED: return "shared"; case MS_SLAVE: return "slave"; case MS_PRIVATE: return "private"; } return NULL; } int mount_propagation_flags_from_string(const char *name, unsigned long *ret) { if (isempty(name)) *ret = 0; else if (streq(name, "shared")) *ret = MS_SHARED; else if (streq(name, "slave")) *ret = MS_SLAVE; else if (streq(name, "private")) *ret = MS_PRIVATE; else return -EINVAL; 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 instread 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_QUOTES); 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; } int dev_is_devtmpfs(void) { _cleanup_fclose_ FILE *proc_self_mountinfo = NULL; int mount_id, r; char *e; r = path_get_mnt_id("/dev", &mount_id); if (r < 0) return r; proc_self_mountinfo = fopen("/proc/self/mountinfo", "re"); if (!proc_self_mountinfo) return -errno; (void) __fsetlocking(proc_self_mountinfo, FSETLOCKING_BYCALLER); for (;;) { _cleanup_free_ char *line = NULL; int mid; r = read_line(proc_self_mountinfo, LONG_LINE_MAX, &line); if (r < 0) return r; if (r == 0) break; if (sscanf(line, "%i", &mid) != 1) continue; if (mid != mount_id) continue; e = strstr(line, " - "); if (!e) continue; /* accept any name that starts with the currently expected type */ if (startswith(e + 3, "devtmpfs")) return true; } return false; }