567 lines
22 KiB
C
567 lines
22 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <sys/statvfs.h>
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#include <unistd.h>
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/* Include later */
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#include <libmount.h>
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#include "alloc-util.h"
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#include "escape.h"
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#include "extract-word.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "fs-util.h"
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#include "hashmap.h"
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#include "mount-util.h"
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#include "mountpoint-util.h"
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#include "parse-util.h"
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#include "path-util.h"
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#include "set.h"
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#include "stdio-util.h"
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#include "string-util.h"
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#include "strv.h"
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int umount_recursive(const char *prefix, int flags) {
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int n = 0, r;
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bool again;
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/* Try to umount everything recursively below a
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* directory. Also, take care of stacked mounts, and keep
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* unmounting them until they are gone. */
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do {
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_cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
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again = false;
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r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo);
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if (r < 0)
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return r;
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for (;;) {
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_cleanup_free_ char *path = NULL, *p = NULL;
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int k;
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k = fscanf(proc_self_mountinfo,
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"%*s " /* (1) mount id */
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"%*s " /* (2) parent id */
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"%*s " /* (3) major:minor */
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"%*s " /* (4) root */
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"%ms " /* (5) mount point */
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"%*s" /* (6) mount options */
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"%*[^-]" /* (7) optional fields */
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"- " /* (8) separator */
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"%*s " /* (9) file system type */
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"%*s" /* (10) mount source */
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"%*s" /* (11) mount options 2 */
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"%*[^\n]", /* some rubbish at the end */
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&path);
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if (k != 1) {
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if (k == EOF)
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break;
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continue;
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}
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k = cunescape(path, UNESCAPE_RELAX, &p);
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if (k < 0)
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return k;
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if (!path_startswith(p, prefix))
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continue;
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if (umount2(p, flags) < 0) {
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r = log_debug_errno(errno, "Failed to umount %s: %m", p);
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continue;
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}
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log_debug("Successfully unmounted %s", p);
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again = true;
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n++;
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break;
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}
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} while (again);
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return r < 0 ? r : n;
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}
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static int get_mount_flags(const char *path, unsigned long *flags) {
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struct statvfs buf;
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if (statvfs(path, &buf) < 0)
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return -errno;
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*flags = buf.f_flag;
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return 0;
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}
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/* Use this function only if you do not have direct access to /proc/self/mountinfo but the caller can open it
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* for you. This is the case when /proc is masked or not mounted. Otherwise, use bind_remount_recursive. */
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int bind_remount_recursive_with_mountinfo(
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const char *prefix,
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unsigned long new_flags,
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unsigned long flags_mask,
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char **blacklist,
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FILE *proc_self_mountinfo) {
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_cleanup_set_free_free_ Set *done = NULL;
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_cleanup_free_ char *cleaned = NULL;
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int r;
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assert(proc_self_mountinfo);
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/* Recursively remount a directory (and all its submounts) read-only or read-write. If the directory is already
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* mounted, we reuse the mount and simply mark it MS_BIND|MS_RDONLY (or remove the MS_RDONLY for read-write
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* operation). If it isn't we first make it one. Afterwards we apply MS_BIND|MS_RDONLY (or remove MS_RDONLY) to
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* all submounts we can access, too. When mounts are stacked on the same mount point we only care for each
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* individual "top-level" mount on each point, as we cannot influence/access the underlying mounts anyway. We
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* do not have any effect on future submounts that might get propagated, they migt be writable. This includes
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* future submounts that have been triggered via autofs.
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*
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* If the "blacklist" parameter is specified it may contain a list of subtrees to exclude from the
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* remount operation. Note that we'll ignore the blacklist for the top-level path. */
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cleaned = strdup(prefix);
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if (!cleaned)
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return -ENOMEM;
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path_simplify(cleaned, false);
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done = set_new(&path_hash_ops);
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if (!done)
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return -ENOMEM;
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for (;;) {
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_cleanup_set_free_free_ Set *todo = NULL;
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bool top_autofs = false;
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char *x;
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unsigned long orig_flags;
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todo = set_new(&path_hash_ops);
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if (!todo)
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return -ENOMEM;
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rewind(proc_self_mountinfo);
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for (;;) {
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_cleanup_free_ char *path = NULL, *p = NULL, *type = NULL;
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int k;
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k = fscanf(proc_self_mountinfo,
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"%*s " /* (1) mount id */
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"%*s " /* (2) parent id */
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"%*s " /* (3) major:minor */
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"%*s " /* (4) root */
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"%ms " /* (5) mount point */
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"%*s" /* (6) mount options (superblock) */
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"%*[^-]" /* (7) optional fields */
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"- " /* (8) separator */
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"%ms " /* (9) file system type */
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"%*s" /* (10) mount source */
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"%*s" /* (11) mount options (bind mount) */
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"%*[^\n]", /* some rubbish at the end */
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&path,
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&type);
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if (k != 2) {
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if (k == EOF)
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break;
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continue;
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}
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r = cunescape(path, UNESCAPE_RELAX, &p);
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if (r < 0)
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return r;
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if (!path_startswith(p, cleaned))
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continue;
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/* Ignore this mount if it is blacklisted, but only if it isn't the top-level mount we shall
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* operate on. */
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if (!path_equal(cleaned, p)) {
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bool blacklisted = false;
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char **i;
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STRV_FOREACH(i, blacklist) {
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if (path_equal(*i, cleaned))
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continue;
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if (!path_startswith(*i, cleaned))
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continue;
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if (path_startswith(p, *i)) {
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blacklisted = true;
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log_debug("Not remounting %s blacklisted by %s, called for %s", p, *i, cleaned);
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break;
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}
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}
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if (blacklisted)
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continue;
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}
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/* Let's ignore autofs mounts. If they aren't
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* triggered yet, we want to avoid triggering
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* them, as we don't make any guarantees for
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* future submounts anyway. If they are
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* already triggered, then we will find
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* another entry for this. */
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if (streq(type, "autofs")) {
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top_autofs = top_autofs || path_equal(cleaned, p);
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continue;
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}
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if (!set_contains(done, p)) {
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r = set_consume(todo, p);
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p = NULL;
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if (r == -EEXIST)
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continue;
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if (r < 0)
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return r;
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}
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}
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/* If we have no submounts to process anymore and if
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* the root is either already done, or an autofs, we
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* are done */
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if (set_isempty(todo) &&
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(top_autofs || set_contains(done, cleaned)))
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return 0;
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if (!set_contains(done, cleaned) &&
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!set_contains(todo, cleaned)) {
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/* The prefix directory itself is not yet a mount, make it one. */
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if (mount(cleaned, cleaned, NULL, MS_BIND|MS_REC, NULL) < 0)
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return -errno;
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orig_flags = 0;
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(void) get_mount_flags(cleaned, &orig_flags);
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orig_flags &= ~MS_RDONLY;
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if (mount(NULL, cleaned, NULL, (orig_flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags, NULL) < 0)
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return -errno;
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log_debug("Made top-level directory %s a mount point.", prefix);
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r = set_put_strdup(done, cleaned);
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if (r < 0)
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return r;
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}
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while ((x = set_steal_first(todo))) {
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r = set_consume(done, x);
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if (IN_SET(r, 0, -EEXIST))
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continue;
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if (r < 0)
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return r;
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/* Deal with mount points that are obstructed by a later mount */
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r = path_is_mount_point(x, NULL, 0);
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if (IN_SET(r, 0, -ENOENT))
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continue;
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if (IN_SET(r, -EACCES, -EPERM)) {
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/* Even if root user invoke this, submounts under private FUSE or NFS mount points
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* may not be acceessed. E.g.,
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*
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* $ bindfs --no-allow-other ~/mnt/mnt ~/mnt/mnt
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* $ bindfs --no-allow-other ~/mnt ~/mnt
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*
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* Then, root user cannot access the mount point ~/mnt/mnt.
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* In such cases, the submounts are ignored, as we have no way to manage them. */
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log_debug_errno(r, "Failed to determine '%s' is mount point or not, ignoring: %m", x);
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continue;
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}
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if (r < 0)
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return r;
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/* Try to reuse the original flag set */
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orig_flags = 0;
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(void) get_mount_flags(x, &orig_flags);
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orig_flags &= ~MS_RDONLY;
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if (mount(NULL, x, NULL, (orig_flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags, NULL) < 0)
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return -errno;
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log_debug("Remounted %s read-only.", x);
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}
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}
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}
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int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **blacklist) {
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_cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
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int r;
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r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo);
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if (r < 0)
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return r;
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return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, blacklist, proc_self_mountinfo);
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}
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int mount_move_root(const char *path) {
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assert(path);
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if (chdir(path) < 0)
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return -errno;
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if (mount(path, "/", NULL, MS_MOVE, NULL) < 0)
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return -errno;
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if (chroot(".") < 0)
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return -errno;
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if (chdir("/") < 0)
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return -errno;
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return 0;
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}
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int repeat_unmount(const char *path, int flags) {
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bool done = false;
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assert(path);
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/* If there are multiple mounts on a mount point, this
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* removes them all */
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for (;;) {
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if (umount2(path, flags) < 0) {
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if (errno == EINVAL)
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return done;
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return -errno;
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}
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done = true;
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}
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}
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const char* mode_to_inaccessible_node(mode_t mode) {
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/* This function maps a node type to a corresponding inaccessible file node. These nodes are created during
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* early boot by PID 1. In some cases we lacked the privs to create the character and block devices (maybe
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* because we run in an userns environment, or miss CAP_SYS_MKNOD, or run with a devices policy that excludes
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* device nodes with major and minor of 0), but that's fine, in that case we use an AF_UNIX file node instead,
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* which is not the same, but close enough for most uses. And most importantly, the kernel allows bind mounts
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* from socket nodes to any non-directory file nodes, and that's the most important thing that matters. */
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switch(mode & S_IFMT) {
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case S_IFREG:
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return "/run/systemd/inaccessible/reg";
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case S_IFDIR:
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return "/run/systemd/inaccessible/dir";
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case S_IFCHR:
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if (access("/run/systemd/inaccessible/chr", F_OK) == 0)
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return "/run/systemd/inaccessible/chr";
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return "/run/systemd/inaccessible/sock";
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case S_IFBLK:
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if (access("/run/systemd/inaccessible/blk", F_OK) == 0)
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return "/run/systemd/inaccessible/blk";
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return "/run/systemd/inaccessible/sock";
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case S_IFIFO:
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return "/run/systemd/inaccessible/fifo";
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case S_IFSOCK:
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return "/run/systemd/inaccessible/sock";
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}
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return NULL;
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}
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#define FLAG(name) (flags & name ? STRINGIFY(name) "|" : "")
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static char* mount_flags_to_string(long unsigned flags) {
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char *x;
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_cleanup_free_ char *y = NULL;
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long unsigned overflow;
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overflow = flags & ~(MS_RDONLY |
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MS_NOSUID |
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MS_NODEV |
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MS_NOEXEC |
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MS_SYNCHRONOUS |
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MS_REMOUNT |
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MS_MANDLOCK |
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MS_DIRSYNC |
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MS_NOATIME |
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MS_NODIRATIME |
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MS_BIND |
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MS_MOVE |
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MS_REC |
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MS_SILENT |
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MS_POSIXACL |
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MS_UNBINDABLE |
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MS_PRIVATE |
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MS_SLAVE |
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MS_SHARED |
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MS_RELATIME |
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MS_KERNMOUNT |
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MS_I_VERSION |
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MS_STRICTATIME |
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MS_LAZYTIME);
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if (flags == 0 || overflow != 0)
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if (asprintf(&y, "%lx", overflow) < 0)
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return NULL;
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x = strjoin(FLAG(MS_RDONLY),
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FLAG(MS_NOSUID),
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FLAG(MS_NODEV),
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FLAG(MS_NOEXEC),
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FLAG(MS_SYNCHRONOUS),
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FLAG(MS_REMOUNT),
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FLAG(MS_MANDLOCK),
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FLAG(MS_DIRSYNC),
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FLAG(MS_NOATIME),
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FLAG(MS_NODIRATIME),
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FLAG(MS_BIND),
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FLAG(MS_MOVE),
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FLAG(MS_REC),
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FLAG(MS_SILENT),
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FLAG(MS_POSIXACL),
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FLAG(MS_UNBINDABLE),
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FLAG(MS_PRIVATE),
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FLAG(MS_SLAVE),
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FLAG(MS_SHARED),
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FLAG(MS_RELATIME),
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FLAG(MS_KERNMOUNT),
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FLAG(MS_I_VERSION),
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FLAG(MS_STRICTATIME),
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FLAG(MS_LAZYTIME),
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y);
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if (!x)
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return NULL;
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if (!y)
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x[strlen(x) - 1] = '\0'; /* truncate the last | */
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return x;
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}
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int mount_verbose(
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int error_log_level,
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const char *what,
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const char *where,
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const char *type,
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unsigned long flags,
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const char *options) {
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_cleanup_free_ char *fl = NULL, *o = NULL;
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unsigned long f;
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int r;
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r = mount_option_mangle(options, flags, &f, &o);
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if (r < 0)
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return log_full_errno(error_log_level, r,
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"Failed to mangle mount options %s: %m",
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strempty(options));
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fl = mount_flags_to_string(f);
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if ((f & MS_REMOUNT) && !what && !type)
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log_debug("Remounting %s (%s \"%s\")...",
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where, strnull(fl), strempty(o));
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else if (!what && !type)
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log_debug("Mounting %s (%s \"%s\")...",
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where, strnull(fl), strempty(o));
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else if ((f & MS_BIND) && !type)
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log_debug("Bind-mounting %s on %s (%s \"%s\")...",
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what, where, strnull(fl), strempty(o));
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else if (f & MS_MOVE)
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log_debug("Moving mount %s → %s (%s \"%s\")...",
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what, where, strnull(fl), strempty(o));
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else
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log_debug("Mounting %s on %s (%s \"%s\")...",
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strna(type), where, strnull(fl), strempty(o));
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if (mount(what, where, type, f, o) < 0)
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return log_full_errno(error_log_level, errno,
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"Failed to mount %s (type %s) on %s (%s \"%s\"): %m",
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strna(what), strna(type), where, strnull(fl), strempty(o));
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return 0;
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}
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int umount_verbose(const char *what) {
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log_debug("Umounting %s...", what);
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if (umount(what) < 0)
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return log_error_errno(errno, "Failed to unmount %s: %m", what);
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return 0;
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}
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int mount_option_mangle(
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const char *options,
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unsigned long mount_flags,
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unsigned long *ret_mount_flags,
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char **ret_remaining_options) {
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const struct libmnt_optmap *map;
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_cleanup_free_ char *ret = NULL;
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const char *p;
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int r;
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/* This extracts mount flags from the mount options, and store
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* non-mount-flag options to '*ret_remaining_options'.
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* E.g.,
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* "rw,nosuid,nodev,relatime,size=1630748k,mode=700,uid=1000,gid=1000"
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* is split to MS_NOSUID|MS_NODEV|MS_RELATIME and
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* "size=1630748k,mode=700,uid=1000,gid=1000".
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* See more examples in test-mount-utils.c.
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*
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* Note that if 'options' does not contain any non-mount-flag options,
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* 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;
|
|
}
|