| /*** |
| This file is part of systemd. |
| |
| Copyright 2010 Lennart Poettering |
| |
| systemd is free software; you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, or |
| (at your option) any later version. |
| |
| systemd is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| ***/ |
| |
| #include <errno.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/mount.h> |
| #include <sys/stat.h> |
| #include <sys/statvfs.h> |
| #include <unistd.h> |
| |
| #include "alloc-util.h" |
| #include "escape.h" |
| #include "fd-util.h" |
| #include "fileio.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" |
| |
| 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 -errno; |
| |
| 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) { |
| union file_handle_union h = FILE_HANDLE_INIT, h_parent = FILE_HANDLE_INIT; |
| 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/<fd>. 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 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(fd, filename, &h.handle, &mount_id, flags); |
| if (r < 0) { |
| if (errno == ENOSYS) |
| /* This kernel does not support name_to_handle_at() |
| * fall back to simpler logic. */ |
| goto fallback_fdinfo; |
| else if (errno == 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 |
| return -errno; |
| } |
| |
| r = name_to_handle_at(fd, "", &h_parent.handle, &mount_id_parent, AT_EMPTY_PATH); |
| if (r < 0) { |
| if (errno == 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 |
| return -errno; |
| } |
| |
| /* 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.handle_bytes == h_parent.handle.handle_bytes && |
| h.handle.handle_type == h_parent.handle.handle_type && |
| memcmp(h.handle.f_handle, h_parent.handle.f_handle, h.handle.handle_bytes) == 0) |
| return 1; |
| |
| return mount_id != mount_id_parent; |
| |
| fallback_fdinfo: |
| r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id); |
| if (r == -EOPNOTSUPP) |
| 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, int flags) { |
| _cleanup_close_ int fd = -1; |
| _cleanup_free_ char *canonical = NULL, *parent = NULL; |
| |
| assert(t); |
| |
| 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) { |
| canonical = canonicalize_file_name(t); |
| if (!canonical) |
| return -errno; |
| |
| t = canonical; |
| } |
| |
| parent = dirname_malloc(t); |
| if (!parent) |
| return -ENOMEM; |
| |
| fd = openat(AT_FDCWD, parent, O_DIRECTORY|O_CLOEXEC|O_PATH); |
| if (fd < 0) |
| return -errno; |
| |
| return fd_is_mount_point(fd, basename(t), flags); |
| } |
| |
| 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; |
| |
| 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 = -errno; |
| continue; |
| } |
| |
| 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; |
| } |
| |
| int bind_remount_recursive(const char *prefix, bool ro) { |
| _cleanup_set_free_free_ Set *done = NULL; |
| _cleanup_free_ char *cleaned = NULL; |
| int r; |
| |
| /* 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. */ |
| |
| cleaned = strdup(prefix); |
| if (!cleaned) |
| return -ENOMEM; |
| |
| path_kill_slashes(cleaned); |
| |
| done = set_new(&string_hash_ops); |
| if (!done) |
| return -ENOMEM; |
| |
| for (;;) { |
| _cleanup_fclose_ FILE *proc_self_mountinfo = NULL; |
| _cleanup_set_free_free_ Set *todo = NULL; |
| bool top_autofs = false; |
| char *x; |
| unsigned long orig_flags; |
| |
| todo = set_new(&string_hash_ops); |
| if (!todo) |
| return -ENOMEM; |
| |
| proc_self_mountinfo = fopen("/proc/self/mountinfo", "re"); |
| if (!proc_self_mountinfo) |
| return -errno; |
| |
| 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; |
| |
| /* 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 (path_startswith(p, cleaned) && |
| !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, prefix, NULL, orig_flags|MS_BIND|MS_REMOUNT|(ro ? MS_RDONLY : 0), NULL) < 0) |
| return -errno; |
| |
| 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 (r == -EEXIST || r == 0) |
| continue; |
| if (r < 0) |
| return r; |
| |
| /* Try to reuse the original flag set, but |
| * don't care for errors, in case of |
| * obstructed mounts */ |
| 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) { |
| |
| /* Deal with mount points that are |
| * obstructed by a later mount */ |
| |
| if (errno != ENOENT) |
| return -errno; |
| } |
| |
| } |
| } |
| } |
| |
| 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) { |
| static const char table[] = |
| "afs\0" |
| "cifs\0" |
| "smbfs\0" |
| "sshfs\0" |
| "ncpfs\0" |
| "ncp\0" |
| "nfs\0" |
| "nfs4\0" |
| "gfs\0" |
| "gfs2\0" |
| "glusterfs\0" |
| "pvfs2\0" /* OrangeFS */ |
| ; |
| |
| const char *x; |
| |
| x = startswith(fstype, "fuse."); |
| if (x) |
| fstype = x; |
| |
| return nulstr_contains(table, fstype); |
| } |
| |
| 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; |
| } |
| } |