1 files changed, 150 insertions, 0 deletions
diff --git a/src/remount-fs/remount-fs.c b/src/remount-fs/remount-fs.c
new file mode 100644
index 0000000..d747d60
--- /dev/null
+++ b/src/remount-fs/remount-fs.c
@@ -0,0 +1,150 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <mntent.h>
+#include <sys/prctl.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "env-util.h"
+#include "exit-status.h"
+#include "fstab-util.h"
+#include "log.h"
+#include "main-func.h"
+#include "mount-setup.h"
+#include "mount-util.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "strv.h"
+#include "util.h"
+
+/* Goes through /etc/fstab and remounts all API file systems, applying options that are in /etc/fstab that systemd
+ * might not have respected */
+
+static int track_pid(Hashmap **h, const char *path, pid_t pid) {
+        _cleanup_free_ char *c = NULL;
+        int r;
+
+        assert(h);
+        assert(path);
+        assert(pid_is_valid(pid));
+
+        c = strdup(path);
+        if (!c)
+                return log_oom();
+
+        r = hashmap_ensure_put(h, NULL, PID_TO_PTR(pid), c);
+        if (r == -ENOMEM)
+                return log_oom();
+        if (r < 0)
+                return log_error_errno(r, "Failed to store pid " PID_FMT, pid);
+
+        TAKE_PTR(c);
+        return 0;
+}
+
+static int do_remount(const char *path, bool force_rw, Hashmap **pids) {
+        pid_t pid;
+        int r;
+
+        log_debug("Remounting %s...", path);
+
+        r = safe_fork(force_rw ? "(remount-rw)" : "(remount)",
+                      FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                /* Child */
+                execv(MOUNT_PATH,
+                      STRV_MAKE(MOUNT_PATH,
+                                path,
+                                "-o",
+                                force_rw ? "remount,rw" : "remount"));
+                log_error_errno(errno, "Failed to execute " MOUNT_PATH ": %m");
+                _exit(EXIT_FAILURE);
+        }
+
+        /* Parent */
+        return track_pid(pids, path, pid);
+}
+
+static int run(int argc, char *argv[]) {
+        _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
+        _cleanup_endmntent_ FILE *f = NULL;
+        bool has_root = false;
+        struct mntent* me;
+        int r;
+
+        log_setup();
+
+        if (argc > 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "This program takes no arguments.");
+
+        umask(0022);
+
+        f = setmntent(fstab_path(), "re");
+        if (!f) {
+                if (errno != ENOENT)
+                        return log_error_errno(errno, "Failed to open %s: %m", fstab_path());
+        } else
+                while ((me = getmntent(f))) {
+                        /* Remount the root fs, /usr, and all API VFSs */
+                        if (!mount_point_is_api(me->mnt_dir) &&
+                            !PATH_IN_SET(me->mnt_dir, "/", "/usr"))
+                                continue;
+
+                        if (path_equal(me->mnt_dir, "/"))
+                                has_root = true;
+
+                        r = do_remount(me->mnt_dir, false, &pids);
+                        if (r < 0)
+                                return r;
+                }
+
+        if (!has_root) {
+                /* The $SYSTEMD_REMOUNT_ROOT_RW environment variable is set by systemd-gpt-auto-generator to tell us
+                 * whether to remount things. We honour it only if there's no explicit line in /etc/fstab configured
+                 * which takes precedence. */
+
+                r = getenv_bool("SYSTEMD_REMOUNT_ROOT_RW");
+                if (r < 0 && r != -ENXIO)
+                        log_warning_errno(r, "Failed to parse $SYSTEMD_REMOUNT_ROOT_RW, ignoring: %m");
+
+                if (r > 0) {
+                        r = do_remount("/", true, &pids);
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        r = 0;
+        while (!hashmap_isempty(pids)) {
+                _cleanup_free_ char *s = NULL;
+                siginfo_t si = {};
+
+                if (waitid(P_ALL, 0, &si, WEXITED) < 0) {
+                        if (errno == EINTR)
+                                continue;
+
+                        return log_error_errno(errno, "waitid() failed: %m");
+                }
+
+                s = hashmap_remove(pids, PID_TO_PTR(si.si_pid));
+                if (s &&
+                    !is_clean_exit(si.si_code, si.si_status, EXIT_CLEAN_COMMAND, NULL)) {
+                        if (si.si_code == CLD_EXITED)
+                                log_error(MOUNT_PATH " for %s exited with exit status %i.", s, si.si_status);
+                        else
+                                log_error(MOUNT_PATH " for %s terminated by signal %s.", s, signal_to_string(si.si_status));
+
+                        r = -ENOEXEC;
+                }
+        }
+
+        return r;
+}
+
+DEFINE_MAIN_FUNCTION(run);