On Sun, Feb 10, 2008 at 03:00:31PM -0500, Isaac Dupree wrote:
> Robert Millan wrote:
> >On Sun, Feb 10, 2008 at 01:00:50PM -0500, Isaac Dupree wrote:
> >>anyway if a hash is used that takes (by design) around one second on the
> >>machine (e.g. sha256 repeated thousands? millions? of times), then I
> >>suppose the time taken to erase the memory used by GRUB would be trivial
> >>in comparison, assuming(rightly or wrongly) a good implementation...
> >
> >The problem is not time, it's just to find the right way to do it.
>
> yeah. probably involves thinking about GRUB's allocation and
> deallocation mechanisms, which I don't know anything about and don't
> have time to investigate :-/
This should address your concern. As to why I propose to put this in unset
command rather than kernel, since GRUB itself doesn't have any mechanisms
where a variable would contain sensible information, I think it's better to
protect user variables only.
--
Robert Millan
<GPLv2> I know my rights; I want my phone call!
<DRM> What use is a phone call… if you are unable to speak?
(as seen on /.)
2008-02-10 Robert Millan <[EMAIL PROTECTED]>
* normal/command.c (unset_command): Erase the contents of the variable
we're about to unset, before actually unsetting it.
diff -x configure -x config.h.in -x CVS -x '*~' -x '*.mk' -urp ../grub2/normal/command.c ./normal/command.c
--- ../grub2/normal/command.c 2007-07-22 01:32:29.000000000 +0200
+++ ./normal/command.c 2008-02-10 21:42:44.000000000 +0100
@@ -274,10 +274,19 @@ static grub_err_t
unset_command (struct grub_arg_list *state __attribute__ ((unused)),
int argc, char **args)
{
+ char *value;
+
if (argc < 1)
return grub_error (GRUB_ERR_BAD_ARGUMENT,
"no environment variable specified");
+ value = grub_env_get (args[0]);
+
+ /* Users may store sensitive information in their variables (e.g. passwords),
+ so erase its content here when they choose to unset them. */
+ if (value)
+ grub_memset (value, 0, grub_strlen (value));
+
grub_env_unset (args[0]);
return 0;
}
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