Adding upstream version 241.upstream/241upstream

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

1 files changed, 922 insertions, 0 deletions

diff --git a/src/fstab-generator/fstab-generator.c b/src/fstab-generator/fstab-generator.c
new file mode 100644
index 0000000..55a8242
--- /dev/null
+++ b/src/fstab-generator/fstab-generator.c
@@ -0,0 +1,922 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <mntent.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio_ext.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "fstab-util.h"
+#include "generator.h"
+#include "log.h"
+#include "main-func.h"
+#include "mkdir.h"
+#include "mount-setup.h"
+#include "mount-util.h"
+#include "mountpoint-util.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "proc-cmdline.h"
+#include "special.h"
+#include "specifier.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "unit-name.h"
+#include "util.h"
+#include "virt.h"
+#include "volatile-util.h"
+
+typedef enum MountpointFlags {
+        NOAUTO    = 1 << 0,
+        NOFAIL    = 1 << 1,
+        AUTOMOUNT = 1 << 2,
+        MAKEFS    = 1 << 3,
+        GROWFS    = 1 << 4,
+} MountpointFlags;
+
+static const char *arg_dest = NULL;
+static const char *arg_dest_late = NULL;
+static bool arg_fstab_enabled = true;
+static char *arg_root_what = NULL;
+static char *arg_root_fstype = NULL;
+static char *arg_root_options = NULL;
+static char *arg_root_hash = NULL;
+static int arg_root_rw = -1;
+static char *arg_usr_what = NULL;
+static char *arg_usr_fstype = NULL;
+static char *arg_usr_options = NULL;
+static VolatileMode arg_volatile_mode = _VOLATILE_MODE_INVALID;
+
+STATIC_DESTRUCTOR_REGISTER(arg_root_what, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_root_fstype, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_root_options, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_root_hash, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_usr_what, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_usr_fstype, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_usr_options, freep);
+
+static int write_options(FILE *f, const char *options) {
+        _cleanup_free_ char *o = NULL;
+
+        if (isempty(options))
+                return 0;
+
+        if (streq(options, "defaults"))
+                return 0;
+
+        o = specifier_escape(options);
+        if (!o)
+                return log_oom();
+
+        fprintf(f, "Options=%s\n", o);
+        return 1;
+}
+
+static int write_what(FILE *f, const char *what) {
+        _cleanup_free_ char *w = NULL;
+
+        w = specifier_escape(what);
+        if (!w)
+                return log_oom();
+
+        fprintf(f, "What=%s\n", w);
+        return 1;
+}
+
+static int add_swap(
+                const char *what,
+                struct mntent *me,
+                MountpointFlags flags) {
+
+        _cleanup_free_ char *name = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        int r;
+
+        assert(what);
+        assert(me);
+
+        if (access("/proc/swaps", F_OK) < 0) {
+                log_info("Swap not supported, ignoring fstab swap entry for %s.", what);
+                return 0;
+        }
+
+        if (detect_container() > 0) {
+                log_info("Running in a container, ignoring fstab swap entry for %s.", what);
+                return 0;
+        }
+
+        r = unit_name_from_path(what, ".swap", &name);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate unit name: %m");
+
+        r = generator_open_unit_file(arg_dest, "/etc/fstab", name, &f);
+        if (r < 0)
+                return r;
+
+        fputs("# Automatically generated by systemd-fstab-generator\n\n"
+              "[Unit]\n"
+              "SourcePath=/etc/fstab\n"
+              "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n\n"
+              "[Swap]\n", f);
+
+        r = write_what(f, what);
+        if (r < 0)
+                return r;
+
+        r = write_options(f, me->mnt_opts);
+        if (r < 0)
+                return r;
+
+        r = fflush_and_check(f);
+        if (r < 0)
+                return log_error_errno(r, "Failed to write unit file %s: %m", name);
+
+        /* use what as where, to have a nicer error message */
+        r = generator_write_timeouts(arg_dest, what, what, me->mnt_opts, NULL);
+        if (r < 0)
+                return r;
+
+        if (flags & MAKEFS) {
+                r = generator_hook_up_mkswap(arg_dest, what);
+                if (r < 0)
+                        return r;
+        }
+
+        if (flags & GROWFS)
+                /* TODO: swap devices must be wiped and recreated */
+                log_warning("%s: growing swap devices is currently unsupported.", what);
+
+        if (!(flags & NOAUTO)) {
+                r = generator_add_symlink(arg_dest, SPECIAL_SWAP_TARGET,
+                                          (flags & NOFAIL) ? "wants" : "requires", name);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static bool mount_is_network(struct mntent *me) {
+        assert(me);
+
+        return fstab_test_option(me->mnt_opts, "_netdev\0") ||
+               fstype_is_network(me->mnt_type);
+}
+
+static bool mount_in_initrd(struct mntent *me) {
+        assert(me);
+
+        return fstab_test_option(me->mnt_opts, "x-initrd.mount\0") ||
+               streq(me->mnt_dir, "/usr");
+}
+
+static int write_timeout(FILE *f, const char *where, const char *opts,
+                         const char *filter, const char *variable) {
+        _cleanup_free_ char *timeout = NULL;
+        char timespan[FORMAT_TIMESPAN_MAX];
+        usec_t u;
+        int r;
+
+        r = fstab_filter_options(opts, filter, NULL, &timeout, NULL);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to parse options: %m");
+        if (r == 0)
+                return 0;
+
+        r = parse_sec_fix_0(timeout, &u);
+        if (r < 0) {
+                log_warning("Failed to parse timeout for %s, ignoring: %s", where, timeout);
+                return 0;
+        }
+
+        fprintf(f, "%s=%s\n", variable, format_timespan(timespan, sizeof(timespan), u, 0));
+
+        return 0;
+}
+
+static int write_idle_timeout(FILE *f, const char *where, const char *opts) {
+        return write_timeout(f, where, opts,
+                             "x-systemd.idle-timeout\0", "TimeoutIdleSec");
+}
+
+static int write_mount_timeout(FILE *f, const char *where, const char *opts) {
+        return write_timeout(f, where, opts,
+                             "x-systemd.mount-timeout\0", "TimeoutSec");
+}
+
+static int write_dependency(FILE *f, const char *opts,
+                const char *filter, const char *format) {
+        _cleanup_strv_free_ char **names = NULL, **units = NULL;
+        _cleanup_free_ char *res = NULL;
+        char **s;
+        int r;
+
+        assert(f);
+        assert(opts);
+
+        r = fstab_extract_values(opts, filter, &names);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to parse options: %m");
+        if (r == 0)
+                return 0;
+
+        STRV_FOREACH(s, names) {
+                char *x;
+
+                r = unit_name_mangle_with_suffix(*s, 0, ".mount", &x);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to generate unit name: %m");
+                r = strv_consume(&units, x);
+                if (r < 0)
+                        return log_oom();
+        }
+
+        if (units) {
+                res = strv_join(units, " ");
+                if (!res)
+                        return log_oom();
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+                fprintf(f, format, res);
+#pragma GCC diagnostic pop
+        }
+
+        return 0;
+}
+
+static int write_after(FILE *f, const char *opts) {
+        return write_dependency(f, opts, "x-systemd.after", "After=%1$s\n");
+}
+
+static int write_requires_after(FILE *f, const char *opts) {
+        return write_dependency(f, opts,
+                                "x-systemd.requires", "After=%1$s\nRequires=%1$s\n");
+}
+
+static int write_before(FILE *f, const char *opts) {
+        return write_dependency(f, opts,
+                                "x-systemd.before", "Before=%1$s\n");
+}
+
+static int write_requires_mounts_for(FILE *f, const char *opts) {
+        _cleanup_strv_free_ char **paths = NULL, **paths_escaped = NULL;
+        _cleanup_free_ char *res = NULL;
+        int r;
+
+        assert(f);
+        assert(opts);
+
+        r = fstab_extract_values(opts, "x-systemd.requires-mounts-for", &paths);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to parse options: %m");
+        if (r == 0)
+                return 0;
+
+        r = specifier_escape_strv(paths, &paths_escaped);
+        if (r < 0)
+                return log_error_errno(r, "Failed to escape paths: %m");
+
+        res = strv_join(paths_escaped, " ");
+        if (!res)
+                return log_oom();
+
+        fprintf(f, "RequiresMountsFor=%s\n", res);
+
+        return 0;
+}
+
+static int add_mount(
+                const char *dest,
+                const char *what,
+                const char *where,
+                const char *original_where,
+                const char *fstype,
+                const char *opts,
+                int passno,
+                MountpointFlags flags,
+                const char *post,
+                const char *source) {
+
+        _cleanup_free_ char
+                *name = NULL,
+                *automount_name = NULL,
+                *filtered = NULL,
+                *where_escaped = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        int r;
+
+        assert(what);
+        assert(where);
+        assert(opts);
+        assert(post);
+        assert(source);
+
+        if (streq_ptr(fstype, "autofs"))
+                return 0;
+
+        if (!is_path(where)) {
+                log_warning("Mount point %s is not a valid path, ignoring.", where);
+                return 0;
+        }
+
+        if (mount_point_is_api(where) ||
+            mount_point_ignore(where))
+                return 0;
+
+        if (path_equal(where, "/")) {
+                if (flags & NOAUTO)
+                        log_warning("Ignoring \"noauto\" for root device");
+                if (flags & NOFAIL)
+                        log_warning("Ignoring \"nofail\" for root device");
+                if (flags & AUTOMOUNT)
+                        log_warning("Ignoring automount option for root device");
+
+                SET_FLAG(flags, NOAUTO | NOFAIL | AUTOMOUNT, false);
+        }
+
+        r = unit_name_from_path(where, ".mount", &name);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate unit name: %m");
+
+        r = generator_open_unit_file(dest, "/etc/fstab", name, &f);
+        if (r < 0)
+                return r;
+
+        fprintf(f,
+                "[Unit]\n"
+                "SourcePath=%s\n"
+                "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n",
+                source);
+
+        if (STRPTR_IN_SET(fstype, "nfs", "nfs4") && !(flags & AUTOMOUNT) &&
+            fstab_test_yes_no_option(opts, "bg\0" "fg\0")) {
+                /* The default retry timeout that mount.nfs uses for 'bg' mounts
+                 * is 10000 minutes, where as it uses 2 minutes for 'fg' mounts.
+                 * As we are making  'bg' mounts look like an 'fg' mount to
+                 * mount.nfs (so systemd can manage the job-control aspects of 'bg'),
+                 * we need to explicitly preserve that default, and also ensure
+                 * the systemd mount-timeout doesn't interfere.
+                 * By placing these options first, they can be over-ridden by
+                 * settings in /etc/fstab. */
+                opts = strjoina("x-systemd.mount-timeout=infinity,retry=10000,", opts, ",fg");
+                SET_FLAG(flags, NOFAIL, true);
+        }
+
+        if (!(flags & NOFAIL) && !(flags & AUTOMOUNT))
+                fprintf(f, "Before=%s\n", post);
+
+        if (!(flags & AUTOMOUNT) && opts) {
+                 r = write_after(f, opts);
+                 if (r < 0)
+                         return r;
+                 r = write_requires_after(f, opts);
+                 if (r < 0)
+                         return r;
+                 r = write_before(f, opts);
+                 if (r < 0)
+                         return r;
+                 r = write_requires_mounts_for(f, opts);
+                 if (r < 0)
+                         return r;
+        }
+
+        if (passno != 0) {
+                r = generator_write_fsck_deps(f, dest, what, where, fstype);
+                if (r < 0)
+                        return r;
+        }
+
+        fprintf(f, "\n[Mount]\n");
+        if (original_where)
+                fprintf(f, "# Canonicalized from %s\n", original_where);
+
+        where_escaped = specifier_escape(where);
+        if (!where_escaped)
+                return log_oom();
+        fprintf(f, "Where=%s\n", where_escaped);
+
+        r = write_what(f, what);
+        if (r < 0)
+                return r;
+
+        if (!isempty(fstype) && !streq(fstype, "auto")) {
+                _cleanup_free_ char *t;
+
+                t = specifier_escape(fstype);
+                if (!t)
+                        return -ENOMEM;
+
+                fprintf(f, "Type=%s\n", t);
+        }
+
+        r = generator_write_timeouts(dest, what, where, opts, &filtered);
+        if (r < 0)
+                return r;
+
+        r = generator_write_device_deps(dest, what, where, opts);
+        if (r < 0)
+                return r;
+
+        r = write_mount_timeout(f, where, opts);
+        if (r < 0)
+                return r;
+
+        r = write_options(f, filtered);
+        if (r < 0)
+                return r;
+
+        r = fflush_and_check(f);
+        if (r < 0)
+                return log_error_errno(r, "Failed to write unit file %s: %m", name);
+
+        if (flags & MAKEFS) {
+                r = generator_hook_up_mkfs(dest, what, where, fstype);
+                if (r < 0)
+                        return r;
+        }
+
+        if (flags & GROWFS) {
+                r = generator_hook_up_growfs(dest, where, post);
+                if (r < 0)
+                        return r;
+        }
+
+        if (!(flags & NOAUTO) && !(flags & AUTOMOUNT)) {
+                r = generator_add_symlink(dest, post,
+                                          (flags & NOFAIL) ? "wants" : "requires", name);
+                if (r < 0)
+                        return r;
+        }
+
+        if (flags & AUTOMOUNT) {
+                r = unit_name_from_path(where, ".automount", &automount_name);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to generate unit name: %m");
+
+                fclose(f);
+
+                r = generator_open_unit_file(dest, "/etc/fstab", automount_name, &f);
+                if (r < 0)
+                        return r;
+
+                fprintf(f,
+                        "[Unit]\n"
+                        "SourcePath=%s\n"
+                        "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n",
+                        source);
+
+                fprintf(f, "Before=%s\n", post);
+
+                if (opts) {
+                        r = write_after(f, opts);
+                        if (r < 0)
+                                return r;
+                        r = write_requires_after(f, opts);
+                        if (r < 0)
+                                return r;
+                        r = write_before(f, opts);
+                        if (r < 0)
+                                return r;
+                        r = write_requires_mounts_for(f, opts);
+                        if (r < 0)
+                                return r;
+                }
+
+                fprintf(f,
+                        "\n"
+                        "[Automount]\n"
+                        "Where=%s\n",
+                        where_escaped);
+
+                r = write_idle_timeout(f, where, opts);
+                if (r < 0)
+                        return r;
+
+                r = fflush_and_check(f);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to write unit file %s: %m", automount_name);
+
+                r = generator_add_symlink(dest, post,
+                                          (flags & NOFAIL) ? "wants" : "requires", automount_name);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int parse_fstab(bool initrd) {
+        _cleanup_endmntent_ FILE *f = NULL;
+        const char *fstab_path;
+        struct mntent *me;
+        int r = 0;
+
+        fstab_path = initrd ? "/sysroot/etc/fstab" : "/etc/fstab";
+        f = setmntent(fstab_path, "re");
+        if (!f) {
+                if (errno == ENOENT)
+                        return 0;
+
+                return log_error_errno(errno, "Failed to open %s: %m", fstab_path);
+        }
+
+        while ((me = getmntent(f))) {
+                _cleanup_free_ char *where = NULL, *what = NULL, *canonical_where = NULL;
+                bool makefs, growfs, noauto, nofail;
+                int k;
+
+                if (initrd && !mount_in_initrd(me))
+                        continue;
+
+                what = fstab_node_to_udev_node(me->mnt_fsname);
+                if (!what)
+                        return log_oom();
+
+                if (is_device_path(what) && path_is_read_only_fs("/sys") > 0) {
+                        log_info("Running in a container, ignoring fstab device entry for %s.", what);
+                        continue;
+                }
+
+                where = strdup(me->mnt_dir);
+                if (!where)
+                        return log_oom();
+
+                if (is_path(where)) {
+                        path_simplify(where, false);
+
+                        /* Follow symlinks here; see 5261ba901845c084de5a8fd06500ed09bfb0bd80 which makes sense for
+                         * mount units, but causes problems since it historically worked to have symlinks in e.g.
+                         * /etc/fstab. So we canonicalize here. Note that we use CHASE_NONEXISTENT to handle the case
+                         * where a symlink refers to another mount target; this works assuming the sub-mountpoint
+                         * target is the final directory. */
+                        r = chase_symlinks(where, initrd ? "/sysroot" : NULL,
+                                           CHASE_PREFIX_ROOT | CHASE_NONEXISTENT,
+                                           &canonical_where);
+                        if (r < 0) /* If we can't canonicalize we continue on as if it wasn't a symlink */
+                                log_debug_errno(r, "Failed to read symlink target for %s, ignoring: %m", where);
+                        else if (streq(canonical_where, where)) /* If it was fully canonicalized, suppress the change */
+                                canonical_where = mfree(canonical_where);
+                        else
+                                log_debug("Canonicalized what=%s where=%s to %s", what, where, canonical_where);
+                }
+
+                makefs = fstab_test_option(me->mnt_opts, "x-systemd.makefs\0");
+                growfs = fstab_test_option(me->mnt_opts, "x-systemd.growfs\0");
+                noauto = fstab_test_yes_no_option(me->mnt_opts, "noauto\0" "auto\0");
+                nofail = fstab_test_yes_no_option(me->mnt_opts, "nofail\0" "fail\0");
+
+                log_debug("Found entry what=%s where=%s type=%s makefs=%s nofail=%s noauto=%s",
+                          what, where, me->mnt_type,
+                          yes_no(makefs),
+                          yes_no(noauto), yes_no(nofail));
+
+                if (streq(me->mnt_type, "swap"))
+                        k = add_swap(what, me,
+                                     makefs*MAKEFS | growfs*GROWFS | noauto*NOAUTO | nofail*NOFAIL);
+                else {
+                        bool automount;
+                        const char *post;
+
+                        automount = fstab_test_option(me->mnt_opts,
+                                                      "comment=systemd.automount\0"
+                                                      "x-systemd.automount\0");
+                        if (initrd)
+                                post = SPECIAL_INITRD_FS_TARGET;
+                        else if (mount_is_network(me))
+                                post = SPECIAL_REMOTE_FS_TARGET;
+                        else
+                                post = SPECIAL_LOCAL_FS_TARGET;
+
+                        k = add_mount(arg_dest,
+                                      what,
+                                      canonical_where ?: where,
+                                      canonical_where ? where: NULL,
+                                      me->mnt_type,
+                                      me->mnt_opts,
+                                      me->mnt_passno,
+                                      makefs*MAKEFS | growfs*GROWFS | noauto*NOAUTO | nofail*NOFAIL | automount*AUTOMOUNT,
+                                      post,
+                                      fstab_path);
+                }
+
+                if (r >= 0 && k < 0)
+                        r = k;
+        }
+
+        return r;
+}
+
+static int add_sysroot_mount(void) {
+        _cleanup_free_ char *what = NULL;
+        const char *opts;
+        int r;
+
+        if (isempty(arg_root_what)) {
+                log_debug("Could not find a root= entry on the kernel command line.");
+                return 0;
+        }
+
+        if (streq(arg_root_what, "gpt-auto")) {
+                /* This is handled by the gpt-auto generator */
+                log_debug("Skipping root directory handling, as gpt-auto was requested.");
+                return 0;
+        }
+
+        if (path_equal(arg_root_what, "/dev/nfs")) {
+                /* This is handled by the kernel or the initrd */
+                log_debug("Skipping root directory handling, as /dev/nfs was requested.");
+                return 0;
+        }
+
+        what = fstab_node_to_udev_node(arg_root_what);
+        if (!what)
+                return log_oom();
+
+        if (!arg_root_options)
+                opts = arg_root_rw > 0 ? "rw" : "ro";
+        else if (arg_root_rw >= 0 ||
+                 !fstab_test_option(arg_root_options, "ro\0" "rw\0"))
+                opts = strjoina(arg_root_options, ",", arg_root_rw > 0 ? "rw" : "ro");
+        else
+                opts = arg_root_options;
+
+        log_debug("Found entry what=%s where=/sysroot type=%s", what, strna(arg_root_fstype));
+
+        if (is_device_path(what)) {
+                r = generator_write_initrd_root_device_deps(arg_dest, what);
+                if (r < 0)
+                        return r;
+        }
+
+        return add_mount(arg_dest,
+                         what,
+                         "/sysroot",
+                         NULL,
+                         arg_root_fstype,
+                         opts,
+                         is_device_path(what) ? 1 : 0, /* passno */
+                         0,                            /* makefs off, growfs off, noauto off, nofail off, automount off */
+                         SPECIAL_INITRD_ROOT_FS_TARGET,
+                         "/proc/cmdline");
+}
+
+static int add_sysroot_usr_mount(void) {
+        _cleanup_free_ char *what = NULL;
+        const char *opts;
+
+        if (!arg_usr_what && !arg_usr_fstype && !arg_usr_options)
+                return 0;
+
+        if (arg_root_what && !arg_usr_what) {
+                /* Copy over the root device, in case the /usr mount just differs in a mount option (consider btrfs subvolumes) */
+                arg_usr_what = strdup(arg_root_what);
+                if (!arg_usr_what)
+                        return log_oom();
+        }
+
+        if (arg_root_fstype && !arg_usr_fstype) {
+                arg_usr_fstype = strdup(arg_root_fstype);
+                if (!arg_usr_fstype)
+                        return log_oom();
+        }
+
+        if (arg_root_options && !arg_usr_options) {
+                arg_usr_options = strdup(arg_root_options);
+                if (!arg_usr_options)
+                        return log_oom();
+        }
+
+        if (!arg_usr_what)
+                return 0;
+
+        what = fstab_node_to_udev_node(arg_usr_what);
+        if (!what)
+                return log_oom();
+
+        if (!arg_usr_options)
+                opts = arg_root_rw > 0 ? "rw" : "ro";
+        else if (!fstab_test_option(arg_usr_options, "ro\0" "rw\0"))
+                opts = strjoina(arg_usr_options, ",", arg_root_rw > 0 ? "rw" : "ro");
+        else
+                opts = arg_usr_options;
+
+        log_debug("Found entry what=%s where=/sysroot/usr type=%s", what, strna(arg_usr_fstype));
+        return add_mount(arg_dest,
+                         what,
+                         "/sysroot/usr",
+                         NULL,
+                         arg_usr_fstype,
+                         opts,
+                         is_device_path(what) ? 1 : 0, /* passno */
+                         0,
+                         SPECIAL_INITRD_FS_TARGET,
+                         "/proc/cmdline");
+}
+
+static int add_volatile_root(void) {
+        const char *from, *to;
+
+        if (arg_volatile_mode != VOLATILE_YES)
+                return 0;
+
+        /* Let's add in systemd-remount-volatile.service which will remount the root device to tmpfs if this is
+         * requested, leaving only /usr from the root mount inside. */
+
+        from = strjoina(SYSTEM_DATA_UNIT_PATH "/systemd-volatile-root.service");
+        to = strjoina(arg_dest, "/" SPECIAL_INITRD_ROOT_FS_TARGET, ".requires/systemd-volatile-root.service");
+
+        (void) mkdir_parents(to, 0755);
+
+        if (symlink(from, to) < 0)
+                return log_error_errno(errno, "Failed to hook in volatile remount service: %m");
+
+        return 0;
+}
+
+static int add_volatile_var(void) {
+
+        if (arg_volatile_mode != VOLATILE_STATE)
+                return 0;
+
+        /* If requested, mount /var as tmpfs, but do so only if there's nothing else defined for this. */
+
+        return add_mount(arg_dest_late,
+                         "tmpfs",
+                         "/var",
+                         NULL,
+                         "tmpfs",
+                         "mode=0755",
+                         0,
+                         0,
+                         SPECIAL_LOCAL_FS_TARGET,
+                         "/proc/cmdline");
+}
+
+static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
+        int r;
+
+        /* root=, usr=, usrfstype= and roofstype= may occur more than once, the last
+         * instance should take precedence.  In the case of multiple rootflags=
+         * or usrflags= the arguments should be concatenated */
+
+        if (STR_IN_SET(key, "fstab", "rd.fstab")) {
+
+                r = value ? parse_boolean(value) : 1;
+                if (r < 0)
+                        log_warning("Failed to parse fstab switch %s. Ignoring.", value);
+                else
+                        arg_fstab_enabled = r;
+
+        } else if (streq(key, "root")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (free_and_strdup(&arg_root_what, value) < 0)
+                        return log_oom();
+
+        } else if (streq(key, "rootfstype")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (free_and_strdup(&arg_root_fstype, value) < 0)
+                        return log_oom();
+
+        } else if (streq(key, "rootflags")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (!strextend_with_separator(&arg_root_options, ",", value, NULL))
+                        return log_oom();
+
+        } else if (streq(key, "roothash")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (free_and_strdup(&arg_root_hash, value) < 0)
+                        return log_oom();
+
+        } else if (streq(key, "mount.usr")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (free_and_strdup(&arg_usr_what, value) < 0)
+                        return log_oom();
+
+        } else if (streq(key, "mount.usrfstype")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (free_and_strdup(&arg_usr_fstype, value) < 0)
+                        return log_oom();
+
+        } else if (streq(key, "mount.usrflags")) {
+
+                if (proc_cmdline_value_missing(key, value))
+                        return 0;
+
+                if (!strextend_with_separator(&arg_usr_options, ",", value, NULL))
+                        return log_oom();
+
+        } else if (streq(key, "rw") && !value)
+                arg_root_rw = true;
+        else if (streq(key, "ro") && !value)
+                arg_root_rw = false;
+        else if (streq(key, "systemd.volatile")) {
+                VolatileMode m;
+
+                if (value) {
+                        m = volatile_mode_from_string(value);
+                        if (m < 0)
+                                log_warning("Failed to parse systemd.volatile= argument: %s", value);
+                        else
+                                arg_volatile_mode = m;
+                } else
+                        arg_volatile_mode = VOLATILE_YES;
+        }
+
+        return 0;
+}
+
+static int determine_root(void) {
+        /* If we have a root hash but no root device then Verity is used, and we use the "root" DM device as root. */
+
+        if (arg_root_what)
+                return 0;
+
+        if (!arg_root_hash)
+                return 0;
+
+        arg_root_what = strdup("/dev/mapper/root");
+        if (!arg_root_what)
+                return log_oom();
+
+        log_info("Using verity root device %s.", arg_root_what);
+
+        return 1;
+}
+
+static int run(const char *dest, const char *dest_early, const char *dest_late) {
+        int r;
+
+        assert_se(arg_dest = dest);
+        assert_se(arg_dest_late = dest_late);
+
+        r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, 0);
+        if (r < 0)
+                log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");
+
+        (void) determine_root();
+
+        /* Always honour root= and usr= in the kernel command line if we are in an initrd */
+        if (in_initrd()) {
+                int k;
+
+                r = add_sysroot_mount();
+
+                k = add_sysroot_usr_mount();
+                if (k < 0)
+                        r = k;
+
+                k = add_volatile_root();
+                if (k < 0)
+                        r = k;
+        } else
+                r = add_volatile_var();
+
+        /* Honour /etc/fstab only when that's enabled */
+        if (arg_fstab_enabled) {
+                int k;
+
+                log_debug("Parsing /etc/fstab");
+
+                /* Parse the local /etc/fstab, possibly from the initrd */
+                k = parse_fstab(false);
+                if (k < 0)
+                        r = k;
+
+                /* If running in the initrd also parse the /etc/fstab from the host */
+                if (in_initrd()) {
+                        log_debug("Parsing /sysroot/etc/fstab");
+
+                        k = parse_fstab(true);
+                        if (k < 0)
+                                r = k;
+                }
+        }
+
+        return r;
+}
+
+DEFINE_MAIN_GENERATOR_FUNCTION(run);