Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 699 insertions, 0 deletions

diff --git a/src/core/umount.c b/src/core/umount.c
new file mode 100644
index 0000000..7af0195
--- /dev/null
+++ b/src/core/umount.c
@@ -0,0 +1,699 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+/***
+  Copyright © 2010 ProFUSION embedded systems
+***/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/loop.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/swap.h>
+
+/* This needs to be after sys/mount.h :( */
+#include <libmount.h>
+
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "blockdev-util.h"
+#include "def.h"
+#include "device-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fstab-util.h"
+#include "linux-3.13/dm-ioctl.h"
+#include "mount-setup.h"
+#include "mount-util.h"
+#include "mountpoint-util.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "umount.h"
+#include "util.h"
+#include "virt.h"
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct libmnt_table*, mnt_free_table);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct libmnt_iter*, mnt_free_iter);
+
+static void mount_point_free(MountPoint **head, MountPoint *m) {
+        assert(head);
+        assert(m);
+
+        LIST_REMOVE(mount_point, *head, m);
+
+        free(m->path);
+        free(m->remount_options);
+        free(m);
+}
+
+void mount_points_list_free(MountPoint **head) {
+        assert(head);
+
+        while (*head)
+                mount_point_free(head, *head);
+}
+
+int mount_points_list_get(const char *mountinfo, MountPoint **head) {
+        _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL;
+        _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL;
+        int r;
+
+        assert(head);
+
+        t = mnt_new_table();
+        i = mnt_new_iter(MNT_ITER_FORWARD);
+        if (!t || !i)
+                return log_oom();
+
+        r = mnt_table_parse_mtab(t, mountinfo);
+        if (r < 0)
+                return log_error_errno(r, "Failed to parse %s: %m", mountinfo);
+
+        for (;;) {
+                struct libmnt_fs *fs;
+                const char *path, *fstype;
+                _cleanup_free_ char *options = NULL;
+                _cleanup_free_ char *p = NULL;
+                unsigned long remount_flags = 0u;
+                _cleanup_free_ char *remount_options = NULL;
+                bool try_remount_ro;
+                MountPoint *m;
+
+                r = mnt_table_next_fs(t, i, &fs);
+                if (r == 1)
+                        break;
+                if (r < 0)
+                        return log_error_errno(r, "Failed to get next entry from %s: %m", mountinfo);
+
+                path = mnt_fs_get_target(fs);
+                if (!path)
+                        continue;
+
+                if (cunescape(path, UNESCAPE_RELAX, &p) < 0)
+                        return log_oom();
+
+                fstype = mnt_fs_get_fstype(fs);
+
+                /* Combine the generic VFS options with the FS-specific
+                 * options. Duplicates are not a problem here, because the only
+                 * options that should come up twice are typically ro/rw, which
+                 * are turned into MS_RDONLY or the invertion of it.
+                 *
+                 * Even if there are duplicates later in mount_option_mangle()
+                 * it shouldn't hurt anyways as they override each other.
+                 */
+                if (!strextend_with_separator(&options, ",",
+                                              mnt_fs_get_vfs_options(fs),
+                                              NULL))
+                        return log_oom();
+                if (!strextend_with_separator(&options, ",",
+                                              mnt_fs_get_fs_options(fs),
+                                              NULL))
+                        return log_oom();
+
+                /* Ignore mount points we can't unmount because they
+                 * are API or because we are keeping them open (like
+                 * /dev/console). Also, ignore all mounts below API
+                 * file systems, since they are likely virtual too,
+                 * and hence not worth spending time on. Also, in
+                 * unprivileged containers we might lack the rights to
+                 * unmount these things, hence don't bother. */
+                if (mount_point_is_api(p) ||
+                    mount_point_ignore(p) ||
+                    PATH_STARTSWITH_SET(p, "/dev", "/sys", "/proc"))
+                        continue;
+
+                /* If we are in a container, don't attempt to
+                 * read-only mount anything as that brings no real
+                 * benefits, but might confuse the host, as we remount
+                 * the superblock here, not the bind mount.
+                 *
+                 * If the filesystem is a network fs, also skip the
+                 * remount. It brings no value (we cannot leave
+                 * a "dirty fs") and could hang if the network is down.
+                 * Note that umount2() is more careful and will not
+                 * hang because of the network being down. */
+                try_remount_ro = detect_container() <= 0 &&
+                                 !fstype_is_network(fstype) &&
+                                 !fstype_is_api_vfs(fstype) &&
+                                 !fstype_is_ro(fstype) &&
+                                 !fstab_test_yes_no_option(options, "ro\0rw\0");
+
+                if (try_remount_ro) {
+                        /* mount(2) states that mount flags and options need to be exactly the same
+                         * as they were when the filesystem was mounted, except for the desired
+                         * changes. So we reconstruct both here and adjust them for the later
+                         * remount call too. */
+
+                        r = mnt_fs_get_propagation(fs, &remount_flags);
+                        if (r < 0) {
+                                log_warning_errno(r, "mnt_fs_get_propagation() failed for %s, ignoring: %m", path);
+                                continue;
+                        }
+
+                        r = mount_option_mangle(options, remount_flags, &remount_flags, &remount_options);
+                        if (r < 0) {
+                                log_warning_errno(r, "mount_option_mangle failed for %s, ignoring: %m", path);
+                                continue;
+                        }
+
+                        /* MS_BIND is special. If it is provided it will only make the mount-point
+                         * read-only. If left out, the super block itself is remounted, which we want. */
+                        remount_flags = (remount_flags|MS_REMOUNT|MS_RDONLY) & ~MS_BIND;
+                }
+
+                m = new0(MountPoint, 1);
+                if (!m)
+                        return log_oom();
+
+                free_and_replace(m->path, p);
+                free_and_replace(m->remount_options, remount_options);
+                m->remount_flags = remount_flags;
+                m->try_remount_ro = try_remount_ro;
+
+                LIST_PREPEND(mount_point, *head, m);
+        }
+
+        return 0;
+}
+
+int swap_list_get(const char *swaps, MountPoint **head) {
+        _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL;
+        _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL;
+        int r;
+
+        assert(head);
+
+        t = mnt_new_table();
+        i = mnt_new_iter(MNT_ITER_FORWARD);
+        if (!t || !i)
+                return log_oom();
+
+        r = mnt_table_parse_swaps(t, swaps);
+        if (r < 0)
+                return log_error_errno(r, "Failed to parse %s: %m", swaps);
+
+        for (;;) {
+                struct libmnt_fs *fs;
+
+                MountPoint *swap;
+                const char *source;
+                _cleanup_free_ char *d = NULL;
+
+                r = mnt_table_next_fs(t, i, &fs);
+                if (r == 1)
+                        break;
+                if (r < 0)
+                        return log_error_errno(r, "Failed to get next entry from %s: %m", swaps);
+
+                source = mnt_fs_get_source(fs);
+                if (!source)
+                        continue;
+
+                r = cunescape(source, UNESCAPE_RELAX, &d);
+                if (r < 0)
+                        return r;
+
+                swap = new0(MountPoint, 1);
+                if (!swap)
+                        return -ENOMEM;
+
+                free_and_replace(swap->path, d);
+                LIST_PREPEND(mount_point, *head, swap);
+        }
+
+        return 0;
+}
+
+static int loopback_list_get(MountPoint **head) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        sd_device *d;
+        int r;
+
+        assert(head);
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysname(e, "loop*");
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysattr(e, "loop/backing_file", NULL, true);
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                _cleanup_free_ char *p = NULL;
+                const char *dn;
+                MountPoint *lb;
+
+                if (sd_device_get_devname(d, &dn) < 0)
+                        continue;
+
+                p = strdup(dn);
+                if (!p)
+                        return -ENOMEM;
+
+                lb = new(MountPoint, 1);
+                if (!lb)
+                        return -ENOMEM;
+
+                *lb = (MountPoint) {
+                        .path = TAKE_PTR(p),
+                };
+
+                LIST_PREPEND(mount_point, *head, lb);
+        }
+
+        return 0;
+}
+
+static int dm_list_get(MountPoint **head) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        sd_device *d;
+        int r;
+
+        assert(head);
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysname(e, "dm-*");
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                _cleanup_free_ char *p = NULL;
+                const char *dn;
+                MountPoint *m;
+                dev_t devnum;
+
+                if (sd_device_get_devnum(d, &devnum) < 0 ||
+                    sd_device_get_devname(d, &dn) < 0)
+                        continue;
+
+                p = strdup(dn);
+                if (!p)
+                        return -ENOMEM;
+
+                m = new(MountPoint, 1);
+                if (!m)
+                        return -ENOMEM;
+
+                *m = (MountPoint) {
+                        .path = TAKE_PTR(p),
+                        .devnum = devnum,
+                };
+
+                LIST_PREPEND(mount_point, *head, m);
+        }
+
+        return 0;
+}
+
+static int delete_loopback(const char *device) {
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(device);
+
+        fd = open(device, O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return errno == ENOENT ? 0 : -errno;
+
+        r = ioctl(fd, LOOP_CLR_FD, 0);
+        if (r >= 0)
+                return 1;
+
+        /* ENXIO: not bound, so no error */
+        if (errno == ENXIO)
+                return 0;
+
+        return -errno;
+}
+
+static int delete_dm(dev_t devnum) {
+
+        struct dm_ioctl dm = {
+                .version = {
+                        DM_VERSION_MAJOR,
+                        DM_VERSION_MINOR,
+                        DM_VERSION_PATCHLEVEL
+                },
+                .data_size = sizeof(dm),
+                .dev = devnum,
+        };
+
+        _cleanup_close_ int fd = -1;
+
+        assert(major(devnum) != 0);
+
+        fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (ioctl(fd, DM_DEV_REMOVE, &dm) < 0)
+                return -errno;
+
+        return 0;
+}
+
+static bool nonunmountable_path(const char *path) {
+        return path_equal(path, "/")
+#if ! HAVE_SPLIT_USR
+                || path_equal(path, "/usr")
+#endif
+                || path_startswith(path, "/run/initramfs");
+}
+
+static int remount_with_timeout(MountPoint *m, int umount_log_level) {
+        pid_t pid;
+        int r;
+
+        BLOCK_SIGNALS(SIGCHLD);
+
+        assert(m);
+
+        /* Due to the possiblity of a remount operation hanging, we
+         * fork a child process and set a timeout. If the timeout
+         * lapses, the assumption is that that particular remount
+         * failed. */
+        r = safe_fork("(sd-remount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                log_info("Remounting '%s' read-only in with options '%s'.", m->path, m->remount_options);
+
+                /* Start the mount operation here in the child */
+                r = mount(NULL, m->path, NULL, m->remount_flags, m->remount_options);
+                if (r < 0)
+                        log_full_errno(umount_log_level, errno, "Failed to remount '%s' read-only: %m", m->path);
+
+                _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+        }
+
+        r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC);
+        if (r == -ETIMEDOUT) {
+                log_error_errno(r, "Remounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid);
+                (void) kill(pid, SIGKILL);
+        } else if (r == -EPROTO)
+                log_debug_errno(r, "Remounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid);
+        else if (r < 0)
+                log_error_errno(r, "Remounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid);
+
+        return r;
+}
+
+static int umount_with_timeout(MountPoint *m, int umount_log_level) {
+        pid_t pid;
+        int r;
+
+        BLOCK_SIGNALS(SIGCHLD);
+
+        assert(m);
+
+        /* Due to the possiblity of a umount operation hanging, we
+         * fork a child process and set a timeout. If the timeout
+         * lapses, the assumption is that that particular umount
+         * failed. */
+        r = safe_fork("(sd-umount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                log_info("Unmounting '%s'.", m->path);
+
+                /* Start the mount operation here in the child Using MNT_FORCE
+                 * causes some filesystems (e.g. FUSE and NFS and other network
+                 * filesystems) to abort any pending requests and return -EIO
+                 * rather than blocking indefinitely. If the filesysten is
+                 * "busy", this may allow processes to die, thus making the
+                 * filesystem less busy so the unmount might succeed (rather
+                 * then return EBUSY).*/
+                r = umount2(m->path, MNT_FORCE);
+                if (r < 0)
+                        log_full_errno(umount_log_level, errno, "Failed to unmount %s: %m", m->path);
+
+                _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+        }
+
+        r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC);
+        if (r == -ETIMEDOUT) {
+                log_error_errno(r, "Unmounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid);
+                (void) kill(pid, SIGKILL);
+        } else if (r == -EPROTO)
+                log_debug_errno(r, "Unmounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid);
+        else if (r < 0)
+                log_error_errno(r, "Unmounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid);
+
+        return r;
+}
+
+/* This includes remounting readonly, which changes the kernel mount options.
+ * Therefore the list passed to this function is invalidated, and should not be reused. */
+static int mount_points_list_umount(MountPoint **head, bool *changed, int umount_log_level) {
+        MountPoint *m;
+        int n_failed = 0;
+
+        assert(head);
+        assert(changed);
+
+        LIST_FOREACH(mount_point, m, *head) {
+                if (m->try_remount_ro) {
+                        /* We always try to remount directories
+                         * read-only first, before we go on and umount
+                         * them.
+                         *
+                         * Mount points can be stacked. If a mount
+                         * point is stacked below / or /usr, we
+                         * cannot umount or remount it directly,
+                         * since there is no way to refer to the
+                         * underlying mount. There's nothing we can do
+                         * about it for the general case, but we can
+                         * do something about it if it is aliased
+                         * somehwere else via a bind mount. If we
+                         * explicitly remount the super block of that
+                         * alias read-only we hence should be
+                         * relatively safe regarding keeping a dirty fs
+                         * we cannot otherwise see.
+                         *
+                         * Since the remount can hang in the instance of
+                         * remote filesystems, we remount asynchronously
+                         * and skip the subsequent umount if it fails. */
+                        if (remount_with_timeout(m, umount_log_level) < 0) {
+                                /* Remount failed, but try unmounting anyway,
+                                 * unless this is a mount point we want to skip. */
+                                if (nonunmountable_path(m->path)) {
+                                        n_failed++;
+                                        continue;
+                                }
+                        }
+                }
+
+                /* Skip / and /usr since we cannot unmount that
+                 * anyway, since we are running from it. They have
+                 * already been remounted ro. */
+                if (nonunmountable_path(m->path))
+                        continue;
+
+                /* Trying to umount */
+                if (umount_with_timeout(m, umount_log_level) < 0)
+                        n_failed++;
+                else
+                        *changed = true;
+        }
+
+        return n_failed;
+}
+
+static int swap_points_list_off(MountPoint **head, bool *changed) {
+        MountPoint *m, *n;
+        int n_failed = 0;
+
+        assert(head);
+        assert(changed);
+
+        LIST_FOREACH_SAFE(mount_point, m, n, *head) {
+                log_info("Deactivating swap %s.", m->path);
+                if (swapoff(m->path) == 0) {
+                        *changed = true;
+                        mount_point_free(head, m);
+                } else {
+                        log_warning_errno(errno, "Could not deactivate swap %s: %m", m->path);
+                        n_failed++;
+                }
+        }
+
+        return n_failed;
+}
+
+static int loopback_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) {
+        MountPoint *m, *n;
+        int n_failed = 0, k;
+        struct stat root_st;
+
+        assert(head);
+        assert(changed);
+
+        k = lstat("/", &root_st);
+
+        LIST_FOREACH_SAFE(mount_point, m, n, *head) {
+                int r;
+                struct stat loopback_st;
+
+                if (k >= 0 &&
+                    major(root_st.st_dev) != 0 &&
+                    lstat(m->path, &loopback_st) >= 0 &&
+                    root_st.st_dev == loopback_st.st_rdev) {
+                        n_failed++;
+                        continue;
+                }
+
+                log_info("Detaching loopback %s.", m->path);
+                r = delete_loopback(m->path);
+                if (r >= 0) {
+                        if (r > 0)
+                                *changed = true;
+
+                        mount_point_free(head, m);
+                } else {
+                        log_full_errno(umount_log_level, errno, "Could not detach loopback %s: %m", m->path);
+                        n_failed++;
+                }
+        }
+
+        return n_failed;
+}
+
+static int dm_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) {
+        MountPoint *m, *n;
+        int n_failed = 0, r;
+        dev_t rootdev;
+
+        assert(head);
+        assert(changed);
+
+        r = get_block_device("/", &rootdev);
+        if (r <= 0)
+                rootdev = 0;
+
+        LIST_FOREACH_SAFE(mount_point, m, n, *head) {
+
+                if (major(rootdev) != 0 && rootdev == m->devnum) {
+                        n_failed ++;
+                        continue;
+                }
+
+                log_info("Detaching DM %u:%u.", major(m->devnum), minor(m->devnum));
+                r = delete_dm(m->devnum);
+                if (r >= 0) {
+                        *changed = true;
+                        mount_point_free(head, m);
+                } else {
+                        log_full_errno(umount_log_level, errno, "Could not detach DM %s: %m", m->path);
+                        n_failed++;
+                }
+        }
+
+        return n_failed;
+}
+
+static int umount_all_once(bool *changed, int umount_log_level) {
+        int r;
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head);
+
+        assert(changed);
+
+        LIST_HEAD_INIT(mp_list_head);
+        r = mount_points_list_get(NULL, &mp_list_head);
+        if (r < 0)
+                return r;
+
+        return mount_points_list_umount(&mp_list_head, changed, umount_log_level);
+}
+
+int umount_all(bool *changed, int umount_log_level) {
+        bool umount_changed;
+        int r;
+
+        assert(changed);
+
+        /* Retry umount, until nothing can be umounted anymore. Mounts are
+         * processed in order, newest first. The retries are needed when
+         * an old mount has been moved, to a path inside a newer mount. */
+        do {
+                umount_changed = false;
+
+                r = umount_all_once(&umount_changed, umount_log_level);
+                if (umount_changed)
+                        *changed = true;
+        } while (umount_changed);
+
+        return r;
+}
+
+int swapoff_all(bool *changed) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, swap_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(swap_list_head);
+
+        r = swap_list_get(NULL, &swap_list_head);
+        if (r < 0)
+                return r;
+
+        return swap_points_list_off(&swap_list_head, changed);
+}
+
+int loopback_detach_all(bool *changed, int umount_log_level) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, loopback_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(loopback_list_head);
+
+        r = loopback_list_get(&loopback_list_head);
+        if (r < 0)
+                return r;
+
+        return loopback_points_list_detach(&loopback_list_head, changed, umount_log_level);
+}
+
+int dm_detach_all(bool *changed, int umount_log_level) {
+        _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, dm_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(dm_list_head);
+
+        r = dm_list_get(&dm_list_head);
+        if (r < 0)
+                return r;
+
+        return dm_points_list_detach(&dm_list_head, changed, umount_log_level);
+}