Frostyard

Analysis Summary

Based on systemd source code analysis, the current code is INCORRECT.

Evidence from systemd Source

1. fstab-generator.c (mount_array_add function)

static int mount_array_add(bool for_initrd, const char *str) {
        _cleanup_free_ char *what = NULL, *where = NULL, *fstype = NULL, *options = NULL;
        int r;

        r = extract_many_words(&str, ":", EXTRACT_CUNESCAPE | EXTRACT_DONT_COALESCE_SEPARATORS,
                               &what, &where, &fstype, &options);
        if (r < 0)
                return r;
        if (r < 2)
                return -EINVAL;
        if (!isempty(str))
                return -EINVAL;

        return mount_array_add_internal(for_initrd, TAKE_PTR(what), TAKE_PTR(where), fstype, TAKE_PTR(options));
}

Parse order: what:where:fstype:options

2. vmspawn.c Usage Example

if (strv_extendf(&arg_kernel_cmdline_extra, "systemd.mount-extra=\"%s:%s:virtiofs:%s\"",
                 id, clean_target, mount->read_only ? "ro" : "rw") < 0)

Format: <id>:<clean_target>:virtiofs:<mount_options>

  • id = device/source identifier
  • clean_target = mount point destination
  • virtiofs = filesystem type
  • mount options

3. Standard mount(8) Terminology

From mount(8) manpage and fstab(5):

  • what = device/source (the thing to mount FROM)
  • where = mount point (the place to mount TO)

Example: mount /dev/sda1 /mnt -> mount WHAT (/dev/sda1) WHERE (/mnt)

Current Code (WRONG)

bootloader.go line 251 and 362:

"systemd.mount-extra=/var:UUID=" + varUUID + ":ext4:defaults"

This is parsed as:

  • what = /var (mount point - WRONG!)
  • where = UUID=... (device - WRONG!)
  • fstype = ext4
  • options = defaults

Correct Format

Should be:

"systemd.mount-extra=UUID=" + varUUID + ":/var:ext4:defaults"

This would be parsed as:

  • what = UUID=... (device - CORRECT!)
  • where = /var (mount point - CORRECT!)
  • fstype = ext4
  • options = defaults

Impact

This bug would cause systemd to:

  1. Try to mount the mount point /var as a device
  2. Try to mount TO the device UUID
  3. Result in mount failure during boot

The system may fail to boot or /var may not be mounted, leading to various runtime issues.

Files Requiring Fix

  1. /home/bjk/projects/frostyard/nbc/pkg/bootloader.go line 251 (generateGRUBConfig)
  2. /home/bjk/projects/frostyard/nbc/pkg/bootloader.go line 355 (generateSystemdBootConfig)

Both occurrences need the format corrected to:

"systemd.mount-extra=UUID=" + varUUID + ":/var:ext4:defaults"