| /* SPDX-License-Identifier: LGPL-2.1+ */ |
| |
| #include <errno.h> |
| #include <stdlib.h> |
| #include <sys/mount.h> |
| #include <sys/stat.h> |
| #include <sys/statvfs.h> |
| #include <unistd.h> |
| |
| #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; |
| } |