]> git.ipfire.org Git - thirdparty/systemd.git/blobdiff - src/nspawn/nspawn-mount.c
nspawn: split out VolatileMode definitions
[thirdparty/systemd.git] / src / nspawn / nspawn-mount.c
index 115de64cf934f3a098d9f0b376bec2d0bda1e962..72c007f204c657472dc153f3b247bb6f0a5cc025 100644 (file)
@@ -47,7 +47,7 @@ CustomMount* custom_mount_add(CustomMount **l, unsigned *n, CustomMountType t) {
         assert(t >= 0);
         assert(t < _CUSTOM_MOUNT_TYPE_MAX);
 
-        c = realloc(*l, (*n + 1) * sizeof(CustomMount));
+        c = realloc_multiply(*l, (*n + 1), sizeof(CustomMount));
         if (!c)
                 return NULL;
 
@@ -75,13 +75,18 @@ void custom_mount_free_all(CustomMount *l, unsigned n) {
                         free(m->work_dir);
                 }
 
+                if (m->rm_rf_tmpdir) {
+                        (void) rm_rf(m->rm_rf_tmpdir, REMOVE_ROOT|REMOVE_PHYSICAL);
+                        free(m->rm_rf_tmpdir);
+                }
+
                 strv_free(m->lower);
         }
 
         free(l);
 }
 
-int custom_mount_compare(const void *a, const void *b) {
+static int custom_mount_compare(const void *a, const void *b) {
         const CustomMount *x = a, *y = b;
         int r;
 
@@ -97,6 +102,109 @@ int custom_mount_compare(const void *a, const void *b) {
         return 0;
 }
 
+static bool source_path_is_valid(const char *p) {
+        assert(p);
+
+        if (*p == '+')
+                p++;
+
+        return path_is_absolute(p);
+}
+
+static char *resolve_source_path(const char *dest, const char *source) {
+
+        if (!source)
+                return NULL;
+
+        if (source[0] == '+')
+                return prefix_root(dest, source + 1);
+
+        return strdup(source);
+}
+
+int custom_mount_prepare_all(const char *dest, CustomMount *l, unsigned n) {
+        unsigned i;
+        int r;
+
+        /* Prepare all custom mounts. This will make source we know all temporary directories. This is called in the
+         * parent process, so that we know the temporary directories to remove on exit before we fork off the
+         * children. */
+
+        assert(l || n == 0);
+
+        /* Order the custom mounts, and make sure we have a working directory */
+        qsort_safe(l, n, sizeof(CustomMount), custom_mount_compare);
+
+        for (i = 0; i < n; i++) {
+                CustomMount *m = l + i;
+
+                if (m->source) {
+                        char *s;
+
+                        s = resolve_source_path(dest, m->source);
+                        if (!s)
+                                return log_oom();
+
+                        free(m->source);
+                        m->source = s;
+                } else {
+                        /* No source specified? In that case, use a throw-away temporary directory in /var/tmp */
+
+                        m->rm_rf_tmpdir = strdup("/var/tmp/nspawn-temp-XXXXXX");
+                        if (!m->rm_rf_tmpdir)
+                                return log_oom();
+
+                        if (!mkdtemp(m->rm_rf_tmpdir)) {
+                                m->rm_rf_tmpdir = mfree(m->rm_rf_tmpdir);
+                                return log_error_errno(errno, "Failed to acquire temporary directory: %m");
+                        }
+
+                        m->source = strjoin(m->rm_rf_tmpdir, "/src");
+                        if (!m->source)
+                                return log_oom();
+
+                        if (mkdir(m->source, 0755) < 0)
+                                return log_error_errno(errno, "Failed to create %s: %m", m->source);
+                }
+
+                if (m->type == CUSTOM_MOUNT_OVERLAY) {
+                        char **j;
+
+                        STRV_FOREACH(j, m->lower) {
+                                char *s;
+
+                                s = resolve_source_path(dest, *j);
+                                if (!s)
+                                        return log_oom();
+
+                                free(*j);
+                                *j = s;
+                        }
+
+                        if (m->work_dir) {
+                                char *s;
+
+                                s = resolve_source_path(dest, m->work_dir);
+                                if (!s)
+                                        return log_oom();
+
+                                free(m->work_dir);
+                                m->work_dir = s;
+                        } else {
+                                assert(m->source);
+
+                                r = tempfn_random(m->source, NULL, &m->work_dir);
+                                if (r < 0)
+                                        return log_error_errno(r, "Failed to acquire working directory: %m");
+                        }
+
+                        (void) mkdir_label(m->work_dir, 0700);
+                }
+        }
+
+        return 0;
+}
+
 int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only) {
         _cleanup_free_ char *source = NULL, *destination = NULL, *opts = NULL;
         const char *p = s;
@@ -111,20 +219,20 @@ int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only
                 return r;
         if (r == 0)
                 return -EINVAL;
-
         if (r == 1) {
-                destination = strdup(source);
+                destination = strdup(source[0] == '+' ? source+1 : source);
                 if (!destination)
                         return -ENOMEM;
         }
-
         if (r == 2 && !isempty(p)) {
                 opts = strdup(p);
                 if (!opts)
                         return -ENOMEM;
         }
 
-        if (!path_is_absolute(source))
+        if (isempty(source))
+                source = NULL;
+        else if (!source_path_is_valid(source))
                 return -EINVAL;
 
         if (!path_is_absolute(destination))
@@ -132,7 +240,7 @@ int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only
 
         m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND);
         if (!m)
-                return log_oom();
+                return -ENOMEM;
 
         m->source = source;
         m->destination = destination;
@@ -180,6 +288,71 @@ int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s) {
         return 0;
 }
 
+int overlay_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only) {
+        _cleanup_free_ char *upper = NULL, *destination = NULL;
+        _cleanup_strv_free_ char **lower = NULL;
+        CustomMount *m;
+        int k;
+
+        k = strv_split_extract(&lower, s, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+        if (k < 0)
+                return k;
+        if (k < 2)
+                return -EADDRNOTAVAIL;
+        if (k == 2) {
+                /* If two parameters are specified, the first one is the lower, the second one the upper directory. And
+                 * we'll also define the destination mount point the same as the upper. */
+
+                if (!source_path_is_valid(lower[0]) ||
+                    !source_path_is_valid(lower[1]))
+                        return -EINVAL;
+
+                upper = lower[1];
+                lower[1] = NULL;
+
+                destination = strdup(upper[0] == '+' ? upper+1 : upper); /* take the destination without "+" prefix */
+                if (!destination)
+                        return -ENOMEM;
+        } else {
+                char **i;
+
+                /* If more than two parameters are specified, the last one is the destination, the second to last one
+                 * the "upper", and all before that the "lower" directories. */
+
+                destination = lower[k - 1];
+                upper = lower[k - 2];
+                lower[k - 2] = NULL;
+
+                STRV_FOREACH(i, lower)
+                        if (!source_path_is_valid(*i))
+                                return -EINVAL;
+
+                /* If the upper directory is unspecified, then let's create it automatically as a throw-away directory
+                 * in /var/tmp */
+                if (isempty(upper))
+                        upper = NULL;
+                else if (!source_path_is_valid(upper))
+                        return -EINVAL;
+
+                if (!path_is_absolute(destination))
+                        return -EINVAL;
+        }
+
+        m = custom_mount_add(l, n, CUSTOM_MOUNT_OVERLAY);
+        if (!m)
+                return -ENOMEM;
+
+        m->destination = destination;
+        m->source = upper;
+        m->lower = lower;
+        m->read_only = read_only;
+
+        upper = destination = NULL;
+        lower = NULL;
+
+        return 0;
+}
+
 static int tmpfs_patch_options(
                 const char *options,
                 bool userns,
@@ -193,11 +366,9 @@ static int tmpfs_patch_options(
         if ((userns && uid_shift != 0) || patch_ids) {
                 assert(uid_shift != UID_INVALID);
 
-                if (options)
-                        (void) asprintf(&buf, "%s,uid=" UID_FMT ",gid=" UID_FMT, options, uid_shift, uid_shift);
-                else
-                        (void) asprintf(&buf, "uid=" UID_FMT ",gid=" UID_FMT, uid_shift, uid_shift);
-                if (!buf)
+                if (asprintf(&buf, "%s%suid=" UID_FMT ",gid=" UID_FMT,
+                             options ?: "", options ? "," : "",
+                             uid_shift, uid_shift) < 0)
                         return -ENOMEM;
 
                 options = buf;
@@ -207,16 +378,12 @@ static int tmpfs_patch_options(
         if (selinux_apifs_context) {
                 char *t;
 
-                if (options)
-                        t = strjoin(options, ",context=\"", selinux_apifs_context, "\"", NULL);
-                else
-                        t = strjoin("context=\"", selinux_apifs_context, "\"", NULL);
-                if (!t) {
-                        free(buf);
+                t = strjoin(options ?: "", options ? "," : "",
+                            "context=\"", selinux_apifs_context, "\"");
+                free(buf);
+                if (!t)
                         return -ENOMEM;
-                }
 
-                free(buf);
                 buf = t;
         }
 #endif
@@ -231,9 +398,10 @@ static int tmpfs_patch_options(
         return !!buf;
 }
 
-int mount_sysfs(const char *dest) {
+int mount_sysfs(const char *dest, MountSettingsMask mount_settings) {
         const char *full, *top, *x;
         int r;
+        unsigned long extra_flags = 0;
 
         top = prefix_roota(dest, "/sys");
         r = path_check_fstype(top, SYSFS_MAGIC);
@@ -250,8 +418,11 @@ int mount_sysfs(const char *dest) {
 
         (void) mkdir(full, 0755);
 
+        if (mount_settings & MOUNT_APPLY_APIVFS_RO)
+                extra_flags |= MS_RDONLY;
+
         r = mount_verbose(LOG_ERR, "sysfs", full, "sysfs",
-                          MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL);
+                          MS_NOSUID|MS_NOEXEC|MS_NODEV|extra_flags, NULL);
         if (r < 0)
                 return r;
 
@@ -273,7 +444,7 @@ int mount_sysfs(const char *dest) {
                         return r;
 
                 r = mount_verbose(LOG_ERR, NULL, to, NULL,
-                                  MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, NULL);
+                                  MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
                 if (r < 0)
                         return r;
         }
@@ -297,10 +468,10 @@ int mount_sysfs(const char *dest) {
         }
 
         return mount_verbose(LOG_ERR, NULL, top, NULL,
-                             MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, NULL);
+                             MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
 }
 
-static int mkdir_userns(const char *path, mode_t mode, bool in_userns, uid_t uid_shift) {
+static int mkdir_userns(const char *path, mode_t mode, MountSettingsMask mask, uid_t uid_shift) {
         int r;
 
         assert(path);
@@ -309,16 +480,20 @@ static int mkdir_userns(const char *path, mode_t mode, bool in_userns, uid_t uid
         if (r < 0 && errno != EEXIST)
                 return -errno;
 
-        if (!in_userns) {
-                r = lchown(path, uid_shift, uid_shift);
-                if (r < 0)
-                        return -errno;
-        }
+        if ((mask & MOUNT_USE_USERNS) == 0)
+                return 0;
+
+        if (mask & MOUNT_IN_USERNS)
+                return 0;
+
+        r = lchown(path, uid_shift, uid_shift);
+        if (r < 0)
+                return -errno;
 
         return 0;
 }
 
-static int mkdir_userns_p(const char *prefix, const char *path, mode_t mode, bool in_userns, uid_t uid_shift) {
+static int mkdir_userns_p(const char *prefix, const char *path, mode_t mode, MountSettingsMask mask, uid_t uid_shift) {
         const char *p, *e;
         int r;
 
@@ -345,17 +520,16 @@ static int mkdir_userns_p(const char *prefix, const char *path, mode_t mode, boo
                 if (prefix && path_startswith(prefix, t))
                         continue;
 
-                r = mkdir_userns(t, mode, in_userns, uid_shift);
+                r = mkdir_userns(t, mode, mask, uid_shift);
                 if (r < 0)
                         return r;
         }
 
-        return mkdir_userns(path, mode, in_userns, uid_shift);
+        return mkdir_userns(path, mode, mask, uid_shift);
 }
 
 int mount_all(const char *dest,
-              bool use_userns, bool in_userns,
-              bool use_netns,
+              MountSettingsMask mount_settings,
               uid_t uid_shift, uid_t uid_range,
               const char *selinux_apifs_context) {
 
@@ -365,48 +539,59 @@ int mount_all(const char *dest,
                 const char *type;
                 const char *options;
                 unsigned long flags;
-                bool fatal;
-                bool in_userns;
-                bool use_netns;
+                MountSettingsMask mount_settings;
         } MountPoint;
 
         static const MountPoint mount_table[] = {
-                { "proc",                "/proc",               "proc",  NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV,                              true,  true,  false },
-                { "/proc/sys",           "/proc/sys",           NULL,    NULL,        MS_BIND,                                                   true,  true,  false },   /* Bind mount first ...*/
-                { "/proc/sys/net",       "/proc/sys/net",       NULL,    NULL,        MS_BIND,                                                   true,  true,  true  },   /* (except for this) */
-                { NULL,                  "/proc/sys",           NULL,    NULL,        MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, true,  true,  false },   /* ... then, make it r/o */
-                { "/proc/sysrq-trigger", "/proc/sysrq-trigger", NULL,    NULL,        MS_BIND,                                                   false, true,  false },   /* Bind mount first ...*/
-                { NULL,                  "/proc/sysrq-trigger", NULL,    NULL,        MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, false, true,  false },   /* ... then, make it r/o */
-                { "tmpfs",               "/sys",                "tmpfs", "mode=755",  MS_NOSUID|MS_NOEXEC|MS_NODEV,                              true,  false, true  },
-                { "sysfs",               "/sys",                "sysfs", NULL,        MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,                    true,  false, false },
-                { "tmpfs",               "/dev",                "tmpfs", "mode=755",  MS_NOSUID|MS_STRICTATIME,                                  true,  false, false },
-                { "tmpfs",               "/dev/shm",            "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         true,  false, false },
-                { "tmpfs",               "/run",                "tmpfs", "mode=755",  MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         true,  false, false },
-                { "tmpfs",               "/tmp",                "tmpfs", "mode=1777", MS_STRICTATIME,                                            true,  true,  false },
+                /* inner child mounts */
+                { "proc",                "/proc",               "proc",  NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV,                              MOUNT_FATAL|MOUNT_IN_USERNS },
+                { "/proc/sys",           "/proc/sys",           NULL,    NULL,        MS_BIND,                                                   MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO },                          /* Bind mount first ...*/
+                { "/proc/sys/net",       "/proc/sys/net",       NULL,    NULL,        MS_BIND,                                                   MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO|MOUNT_APPLY_APIVFS_NETNS }, /* (except for this) */
+                { NULL,                  "/proc/sys",           NULL,    NULL,        MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO },                          /* ... then, make it r/o */
+                { "/proc/sysrq-trigger", "/proc/sysrq-trigger", NULL,    NULL,        MS_BIND,                                                               MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO },                          /* Bind mount first ...*/
+                { NULL,                  "/proc/sysrq-trigger", NULL,    NULL,        MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,             MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO },                          /* ... then, make it r/o */
+
+                /* outer child mounts */
+                { "tmpfs",               "/tmp",                "tmpfs", "mode=1777", MS_STRICTATIME,                                            MOUNT_FATAL },
+                { "tmpfs",               "/sys",                "tmpfs", "mode=755",  MS_NOSUID|MS_NOEXEC|MS_NODEV,                              MOUNT_FATAL|MOUNT_APPLY_APIVFS_NETNS },
+                { "sysfs",               "/sys",                "sysfs", NULL,        MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,                    MOUNT_FATAL|MOUNT_APPLY_APIVFS_RO },    /* skipped if above was mounted */
+                { "sysfs",               "/sys",                "sysfs", NULL,                  MS_NOSUID|MS_NOEXEC|MS_NODEV,                    MOUNT_FATAL },                          /* skipped if above was mounted */
+
+                { "tmpfs",               "/dev",                "tmpfs", "mode=755",  MS_NOSUID|MS_STRICTATIME,                                  MOUNT_FATAL },
+                { "tmpfs",               "/dev/shm",            "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         MOUNT_FATAL },
+                { "tmpfs",               "/run",                "tmpfs", "mode=755",  MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         MOUNT_FATAL },
 #ifdef HAVE_SELINUX
-                { "/sys/fs/selinux",     "/sys/fs/selinux",     NULL,     NULL,       MS_BIND,                                                   false, false, false },  /* Bind mount first */
-                { NULL,                  "/sys/fs/selinux",     NULL,     NULL,       MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, false, false, false },  /* Then, make it r/o */
+                { "/sys/fs/selinux",     "/sys/fs/selinux",     NULL,     NULL,       MS_BIND,                                                   0 },  /* Bind mount first */
+                { NULL,                  "/sys/fs/selinux",     NULL,     NULL,       MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, 0 },  /* Then, make it r/o */
 #endif
         };
 
         unsigned k;
         int r;
+        bool use_userns = (mount_settings & MOUNT_USE_USERNS);
+        bool netns = (mount_settings & MOUNT_APPLY_APIVFS_NETNS);
+        bool ro = (mount_settings & MOUNT_APPLY_APIVFS_RO);
+        bool in_userns = (mount_settings & MOUNT_IN_USERNS);
 
         for (k = 0; k < ELEMENTSOF(mount_table); k++) {
                 _cleanup_free_ char *where = NULL, *options = NULL;
                 const char *o;
+                bool fatal = (mount_table[k].mount_settings & MOUNT_FATAL);
 
-                if (in_userns != mount_table[k].in_userns)
+                if (in_userns != (bool)(mount_table[k].mount_settings & MOUNT_IN_USERNS))
                         continue;
 
-                if (!use_netns && mount_table[k].use_netns)
+                if (!netns && (bool)(mount_table[k].mount_settings & MOUNT_APPLY_APIVFS_NETNS))
                         continue;
 
-                where = prefix_root(dest, mount_table[k].where);
-                if (!where)
-                        return log_oom();
+                if (!ro && (bool)(mount_table[k].mount_settings & MOUNT_APPLY_APIVFS_RO))
+                        continue;
+
+                r = chase_symlinks(mount_table[k].where, dest, CHASE_NONEXISTENT|CHASE_PREFIX_ROOT, &where);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, mount_table[k].where);
 
-                r = path_is_mount_point(where, AT_SYMLINK_FOLLOW);
+                r = path_is_mount_point(where, NULL, 0);
                 if (r < 0 && r != -ENOENT)
                         return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where);
 
@@ -414,9 +599,9 @@ int mount_all(const char *dest,
                 if (mount_table[k].what && r > 0)
                         continue;
 
-                r = mkdir_userns_p(dest, where, 0755, in_userns, uid_shift);
+                r = mkdir_userns_p(dest, where, 0755, mount_settings, uid_shift);
                 if (r < 0 && r != -EEXIST) {
-                        if (mount_table[k].fatal)
+                        if (fatal)
                                 return log_error_errno(r, "Failed to create directory %s: %m", where);
 
                         log_debug_errno(r, "Failed to create directory %s: %m", where);
@@ -435,13 +620,13 @@ int mount_all(const char *dest,
                                 o = options;
                 }
 
-                r = mount_verbose(mount_table[k].fatal ? LOG_ERR : LOG_WARNING,
+                r = mount_verbose(fatal ? LOG_ERR : LOG_DEBUG,
                                   mount_table[k].what,
                                   where,
                                   mount_table[k].type,
                                   mount_table[k].flags,
                                   o);
-                if (r < 0 && mount_table[k].fatal)
+                if (r < 0 && fatal)
                         return r;
         }
 
@@ -452,12 +637,14 @@ static int parse_mount_bind_options(const char *options, unsigned long *mount_fl
         const char *p = options;
         unsigned long flags = *mount_flags;
         char *opts = NULL;
+        int r;
 
         assert(options);
 
         for (;;) {
                 _cleanup_free_ char *word = NULL;
-                int r = extract_first_word(&p, &word, ",", 0);
+
+                r = extract_first_word(&p, &word, ",", 0);
                 if (r < 0)
                         return log_error_errno(r, "Failed to extract mount option: %m");
                 if (r == 0)
@@ -481,12 +668,13 @@ static int parse_mount_bind_options(const char *options, unsigned long *mount_fl
 }
 
 static int mount_bind(const char *dest, CustomMount *m) {
-        struct stat source_st, dest_st;
-        const char *where;
+
+        _cleanup_free_ char *mount_opts = NULL, *where = NULL;
         unsigned long mount_flags = MS_BIND | MS_REC;
-        _cleanup_free_ char *mount_opts = NULL;
+        struct stat source_st, dest_st;
         int r;
 
+        assert(dest);
         assert(m);
 
         if (m->options) {
@@ -498,9 +686,14 @@ static int mount_bind(const char *dest, CustomMount *m) {
         if (stat(m->source, &source_st) < 0)
                 return log_error_errno(errno, "Failed to stat %s: %m", m->source);
 
-        where = prefix_roota(dest, m->destination);
+        r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where);
+        if (r < 0)
+                return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
+        if (r > 0) { /* Path exists already? */
+
+                if (stat(where, &dest_st) < 0)
+                        return log_error_errno(errno, "Failed to stat %s: %m", where);
 
-        if (stat(where, &dest_st) >= 0) {
                 if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode)) {
                         log_error("Cannot bind mount directory %s on file %s.", m->source, where);
                         return -EINVAL;
@@ -511,7 +704,7 @@ static int mount_bind(const char *dest, CustomMount *m) {
                         return -EINVAL;
                 }
 
-        } else if (errno == ENOENT) {
+        } else { /* Path doesn't exist yet? */
                 r = mkdir_parents_label(where, 0755);
                 if (r < 0)
                         return log_error_errno(r, "Failed to make parents of %s: %m", where);
@@ -527,8 +720,7 @@ static int mount_bind(const char *dest, CustomMount *m) {
                 if (r < 0)
                         return log_error_errno(r, "Failed to create mount point %s: %m", where);
 
-        } else
-                return log_error_errno(errno, "Failed to stat %s: %m", where);
+        }
 
         r = mount_verbose(LOG_ERR, m->source, where, NULL, mount_flags, mount_opts);
         if (r < 0)
@@ -549,18 +741,21 @@ static int mount_tmpfs(
                 bool userns, uid_t uid_shift, uid_t uid_range,
                 const char *selinux_apifs_context) {
 
-        const char *where, *options;
-        _cleanup_free_ char *buf = NULL;
+        const char *options;
+        _cleanup_free_ char *buf = NULL, *where = NULL;
         int r;
 
         assert(dest);
         assert(m);
 
-        where = prefix_roota(dest, m->destination);
-
-        r = mkdir_p_label(where, 0755);
-        if (r < 0 && r != -EEXIST)
-                return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
+        r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where);
+        if (r < 0)
+                return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
+        if (r == 0) { /* Doesn't exist yet? */
+                r = mkdir_p_label(where, 0755);
+                if (r < 0)
+                        return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
+        }
 
         r = tmpfs_patch_options(m->options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf);
         if (r < 0)
@@ -570,7 +765,7 @@ static int mount_tmpfs(
         return mount_verbose(LOG_ERR, "tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, options);
 }
 
-static char *joined_and_escaped_lower_dirs(char * const *lower) {
+static char *joined_and_escaped_lower_dirs(char **lower) {
         _cleanup_strv_free_ char **sv = NULL;
 
         sv = strv_copy(lower);
@@ -586,18 +781,22 @@ static char *joined_and_escaped_lower_dirs(char * const *lower) {
 }
 
 static int mount_overlay(const char *dest, CustomMount *m) {
-        _cleanup_free_ char *lower = NULL;
-        const char *where, *options;
+
+        _cleanup_free_ char *lower = NULL, *where = NULL, *escaped_source = NULL;
+        const char *options;
         int r;
 
         assert(dest);
         assert(m);
 
-        where = prefix_roota(dest, m->destination);
-
-        r = mkdir_label(where, 0755);
-        if (r < 0 && r != -EEXIST)
-                return log_error_errno(r, "Creating mount point for overlay %s failed: %m", where);
+        r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where);
+        if (r < 0)
+                return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
+        if (r == 0) { /* Doesn't exist yet? */
+                r = mkdir_label(where, 0755);
+                if (r < 0)
+                        return log_error_errno(r, "Creating mount point for overlay %s failed: %m", where);
+        }
 
         (void) mkdir_p_label(m->source, 0755);
 
@@ -605,23 +804,15 @@ static int mount_overlay(const char *dest, CustomMount *m) {
         if (!lower)
                 return log_oom();
 
-        if (m->read_only) {
-                _cleanup_free_ char *escaped_source = NULL;
-
-                escaped_source = shell_escape(m->source, ",:");
-                if (!escaped_source)
-                        return log_oom();
+        escaped_source = shell_escape(m->source, ",:");
+        if (!escaped_source)
+                return log_oom();
 
+        if (m->read_only)
                 options = strjoina("lowerdir=", escaped_source, ":", lower);
-        } else {
-                _cleanup_free_ char *escaped_source = NULL, *escaped_work_dir = NULL;
-
-                assert(m->work_dir);
-                (void) mkdir_label(m->work_dir, 0700);
+        else {
+                _cleanup_free_ char *escaped_work_dir = NULL;
 
-                escaped_source = shell_escape(m->source, ",:");
-                if (!escaped_source)
-                        return log_oom();
                 escaped_work_dir = shell_escape(m->work_dir, ",:");
                 if (!escaped_work_dir)
                         return log_oom();
@@ -714,14 +905,19 @@ static int get_controllers(Set *subsystems) {
         return 0;
 }
 
-static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controller, const char *hierarchy,
-                                         CGroupUnified unified_requested, bool read_only) {
+static int mount_legacy_cgroup_hierarchy(
+                const char *dest,
+                const char *controller,
+                const char *hierarchy,
+                CGroupUnified unified_requested,
+                bool read_only) {
+
         const char *to, *fstype, *opts;
         int r;
 
         to = strjoina(strempty(dest), "/sys/fs/cgroup/", hierarchy);
 
-        r = path_is_mount_point(to, 0);
+        r = path_is_mount_point(to, dest, 0);
         if (r < 0 && r != -ENOENT)
                 return log_error_errno(r, "Failed to determine if %s is mounted already: %m", to);
         if (r > 0)
@@ -761,8 +957,13 @@ static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controlle
 
 /* Mount a legacy cgroup hierarchy when cgroup namespaces are supported. */
 static int mount_legacy_cgns_supported(
-                CGroupUnified unified_requested, bool userns, uid_t uid_shift,
-                uid_t uid_range, const char *selinux_apifs_context) {
+                const char *dest,
+                CGroupUnified unified_requested,
+                bool userns,
+                uid_t uid_shift,
+                uid_t uid_range,
+                const char *selinux_apifs_context) {
+
         _cleanup_set_free_free_ Set *controllers = NULL;
         const char *cgroup_root = "/sys/fs/cgroup", *c;
         int r;
@@ -770,7 +971,7 @@ static int mount_legacy_cgns_supported(
         (void) mkdir_p(cgroup_root, 0755);
 
         /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */
-        r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW);
+        r = path_is_mount_point(cgroup_root, dest, AT_SYMLINK_FOLLOW);
         if (r < 0)
                 return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m");
         if (r == 0) {
@@ -859,8 +1060,12 @@ skip_controllers:
 /* Mount legacy cgroup hierarchy when cgroup namespaces are unsupported. */
 static int mount_legacy_cgns_unsupported(
                 const char *dest,
-                CGroupUnified unified_requested, bool userns, uid_t uid_shift, uid_t uid_range,
+                CGroupUnified unified_requested,
+                bool userns,
+                uid_t uid_shift,
+                uid_t uid_range,
                 const char *selinux_apifs_context) {
+
         _cleanup_set_free_free_ Set *controllers = NULL;
         const char *cgroup_root;
         int r;
@@ -870,7 +1075,7 @@ static int mount_legacy_cgns_unsupported(
         (void) mkdir_p(cgroup_root, 0755);
 
         /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */
-        r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW);
+        r = path_is_mount_point(cgroup_root, dest, AT_SYMLINK_FOLLOW);
         if (r < 0)
                 return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m");
         if (r == 0) {
@@ -963,7 +1168,7 @@ static int mount_unified_cgroups(const char *dest) {
 
         (void) mkdir_p(p, 0755);
 
-        r = path_is_mount_point(p, AT_SYMLINK_FOLLOW);
+        r = path_is_mount_point(p, dest, AT_SYMLINK_FOLLOW);
         if (r < 0)
                 return log_error_errno(r, "Failed to determine if %s is mounted already: %m", p);
         if (r > 0) {
@@ -983,14 +1188,16 @@ static int mount_unified_cgroups(const char *dest) {
 int mount_cgroups(
                 const char *dest,
                 CGroupUnified unified_requested,
-                bool userns, uid_t uid_shift, uid_t uid_range,
+                bool userns,
+                uid_t uid_shift,
+                uid_t uid_range,
                 const char *selinux_apifs_context,
                 bool use_cgns) {
 
         if (unified_requested >= CGROUP_UNIFIED_ALL)
                 return mount_unified_cgroups(dest);
         else if (use_cgns)
-                return mount_legacy_cgns_supported(unified_requested, userns, uid_shift, uid_range, selinux_apifs_context);
+                return mount_legacy_cgns_supported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context);
 
         return mount_legacy_cgns_unsupported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context);
 }
@@ -1142,21 +1349,3 @@ fail:
         (void) rmdir(template);
         return r;
 }
-
-VolatileMode volatile_mode_from_string(const char *s) {
-        int b;
-
-        if (isempty(s))
-                return _VOLATILE_MODE_INVALID;
-
-        b = parse_boolean(s);
-        if (b > 0)
-                return VOLATILE_YES;
-        if (b == 0)
-                return VOLATILE_NO;
-
-        if (streq(s, "state"))
-                return VOLATILE_STATE;
-
-        return _VOLATILE_MODE_INVALID;
-}