[Bug 221289] Setting loader.conf password prevents autoboot, manual boot still okay; password leaked

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Sun Aug 6 18:53:42 UTC 2017


            Bug ID: 221289
           Summary: Setting loader.conf password prevents autoboot, manual
                    boot still okay; password leaked
           Product: Base System
           Version: 11.1-STABLE
          Hardware: amd64
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: freebsd-bugs at FreeBSD.org
          Reporter: fred at boyce.za.net

Hi Team

As my first bug report, I'll take the opportunity to say thanks! to everyone
who contributes.

I have a fresh install of Free 11.1 in a Parallels VM on my Mac. I used ZFS
auto-layout on installation; ZFS seems unrelated to the problem described here.

Problem 1: Everything is fine until I add 'password="test"' to the
/boot/loader.conf. Rebooting then fails:

    Loading /boot/defaults/loader.conf
    can't load 'kernel'
    no valid kernel found

...and then I'm dropped into the (Forth I think) shell/interpreter.

At this point, if I try to "autoboot", I get these errors again:

    can't load 'kernel'
    no valid kernel found

But if I simply "boot", everything proceeds correctly.

The "show" command reveals:


...and the mystic variable "kernelname" is not set at this point (added to
boot.c in Git revision

This seems to be a problem beyond just my experience:
https://forums.freebsd.org/threads/58292/. It seems to be unrelated to the
previous problem described in

I don't know if it makes a difference that line 80 of sys/boot/common/boot.c
calls loadakernel(0, argc - 1, argv + 1); in the boot case, but only
loadakernel(0, 0, argv); in the autoboot case? (Sorry, I don't have the
understanding to try to debug further).


Problem 2: Once we've failed to boot, and dropped to the interpreter, a simple
"show" will reveal the boot password in plain text as one of the environment
variables. I suppose it would be a kludgy workaround to filter out the password
variables from "command_show" in sys/boot/common/commands.c; but that would
have other unintended consequences for debugging? Is it not possible to
integrate a lightweight hashing function to rather hash the password in
loader.conf for comparison in the boot loader?


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