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Diffstat (limited to 'src/libsystemd-basic/src/mount-util.c')
-rw-r--r--src/libsystemd-basic/src/mount-util.c689
1 files changed, 689 insertions, 0 deletions
diff --git a/src/libsystemd-basic/src/mount-util.c b/src/libsystemd-basic/src/mount-util.c
new file mode 100644
index 0000000000..3148dd0ef2
--- /dev/null
+++ b/src/libsystemd-basic/src/mount-util.c
@@ -0,0 +1,689 @@
+/***
+ 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 "systemd-basic/alloc-util.h"
+#include "systemd-basic/escape.h"
+#include "systemd-basic/fd-util.h"
+#include "systemd-basic/fileio.h"
+#include "systemd-basic/hashmap.h"
+#include "systemd-basic/mount-util.h"
+#include "systemd-basic/parse-util.h"
+#include "systemd-basic/path-util.h"
+#include "systemd-basic/set.h"
+#include "systemd-basic/stdio-util.h"
+#include "systemd-basic/string-util.h"
+#include "systemd-basic/strv.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 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 (IN_SET(r, -EOPNOTSUPP, -EACCES))
+ 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 = 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;
+}
+
+int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) {
+ _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.
+ *
+ * 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_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;
+
+ 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, because 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, prefix, 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 (r == -EEXIST || r == 0)
+ continue;
+ if (r < 0)
+ return r;
+
+ /* Deal with mount points that are obstructed by a later mount */
+ r = path_is_mount_point(x, 0);
+ if (r == -ENOENT || r == 0)
+ 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 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 */
+ "ocfs2\0"
+ "lustre\0"
+ ;
+
+ 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;
+ }
+}
+
+const char* mode_to_inaccessible_node(mode_t mode) {
+ /* This function maps a node type to the correspondent inaccessible node type.
+ * Character and block inaccessible devices may not be created (because major=0 and minor=0),
+ * in such case we map character and block devices to the inaccessible node type socket. */
+ 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, NULL);
+ 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;
+
+ fl = mount_flags_to_string(flags);
+
+ if ((flags & MS_REMOUNT) && !what && !type)
+ log_debug("Remounting %s (%s \"%s\")...",
+ where, strnull(fl), strempty(options));
+ else if (!what && !type)
+ log_debug("Mounting %s (%s \"%s\")...",
+ where, strnull(fl), strempty(options));
+ else if ((flags & MS_BIND) && !type)
+ log_debug("Bind-mounting %s on %s (%s \"%s\")...",
+ what, where, strnull(fl), strempty(options));
+ else
+ log_debug("Mounting %s on %s (%s \"%s\")...",
+ strna(type), where, strnull(fl), strempty(options));
+ if (mount(what, where, type, flags, options) < 0)
+ return log_full_errno(error_log_level, errno,
+ "Failed to mount %s on %s (%s \"%s\"): %m",
+ strna(type), where, strnull(fl), strempty(options));
+ 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;
+}
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