svn commit: r293227 - head/etc

[Devin Teske]

> On Jan 5, 2016, at 8:09 PM, Warner Losh <imp at bsdimp.com> wrote:
> 
> The correct fix is
> 
> <maybe mount -uw>
> chflags -R 0 firstboot
> rm -rf firstboot
> <maybe mount -ur>
> 
> If you still can't remove it, too bad. Checking to make sure it worked really isn't
> the unix way. Sometimes when you do stupid things, stupid results happen.
> 

You forgot to drop the mic and walk out. Looks good to me.
-- 
Devin


> Warner
> 
>> On Tue, Jan 5, 2016 at 8:16 PM, Devin Teske <devin at shxd.cx> wrote:
>> This e-mail is extremely hard to parse  and I think you are mistaken.
>> 
>> The -f flag is more than just a counter to a possible -i
>> 
>> Try to rm a file that has schg
>> You will get a prompt without -i
>> Adding -f will abate the prompt to attempt override of schg flag.
>> 
>> There are more conditions in rm that lead to a prompt than simply those conditions involving -i and adding -f abates them all.
>> 
>> --
>> Devin
>> 
>> > On Jan 5, 2016, at 6:48 PM, Bruce Evans <brde at optusnet.com.au> wrote:
>> >
>> > On Tue, 5 Jan 2016, Ian Lepore wrote:
>> >
>> >>> Log:
>> >>>  Use the more proper -f. Leave /bin/rm in place since that's what
>> >>>  other rc scripts have, though it isn't strictly necessary.
>> >
>> > "proper -f" is hard to parse.  I think you mean:
>> >
>> > Use 'rm -f' to turn off -i in case rm is broken and is an alias which
>> > has -i (and perhaps actually even something resembling rm) in it.  More
>> > precisely, use 'rm -f /usr/bin' to partly defend against the same bug
>> > in /bin/rm (where it would be larger).  Keep using /usr/rm instead of
>> > restoring the use of plain rm since that is what other rc scripts have.
>> > The previous change to use /bin/rm instead of plain rm was neither
>> > necessary nor sufficient for fixing the bug.  Neither is this one, but
>> > it gets closer.  It is a little-known bug in aliases that even absolute
>> > pathnames can be aliased.  So /bin/rm might be aliased to 'rm -ri /'.
>> > Appending -f would accidentally help for that too, by turning it into
>> > a syntax error, instead of accidentally making it more forceful by
>> > turning -ri into -rf.
>> >
>> > Hopefully this is all FUD.  Non-interactive scripts shouldn't source any
>> > files that are not mentioned in the script.  /etc/rc depends on a secure
>> > environment being set up by init and probably gets it since init doesn't
>> > set up much.  sh(1) documents closing the security hole of sourcing the
>> > script in $ENV for non-interactive shells, but was never a problem for
>> > /etc/rc since init must be trusted to not put security holes in $ENV.
>> > But users could put security holes in a sourced config file like
>> > /etc/rc.conf.local.
>> >
>> >>> Modified: head/etc/rc
>> >>> =====================================================================
>> >>> =========
>> >>> --- head/etc/rc    Tue Jan  5 21:20:46 2016    (r293226)
>> >>> +++ head/etc/rc    Tue Jan  5 21:20:47 2016    (r293227)
>> >>> @@ -132,9 +132,9 @@ done
>> >>> # Remove the firstboot sentinel, and reboot if it was requested.
>> >>> if [ -e ${firstboot_sentinel} ]; then
>> >>>    [ ${root_rw_mount} = "yes" ] || mount -uw /
>> >>> -    /bin/rm ${firstboot_sentinel}
>> >>> +    /bin/rm -f ${firstboot_sentinel}
>> >>>    if [ -e ${firstboot_sentinel}-reboot ]; then
>> >>> -        /bin/rm ${firstboot_sentinel}-reboot
>> >>> +        /bin/rm -f ${firstboot_sentinel}-reboot
>> >>>        [ ${root_rw_mount} = "yes" ] || mount -ur /
>> >>>        kill -INT 1
>> >>>    fi
>> >>
>> >> Using rm -f to suppress an error message seems like a bad idea here --
>> >> if the sentinel file can't be removed that implies it's going to do
>> >> firstboot behavior every time it boots, and that's the sort of error
>> >> that should be in-your-face.  Especially on the reboot one because
>> >> you're going to be stuck in a reboot loop with no error message.
>> >
>> > Er, -f on rm only turns off -i and supresses the warning message for
>> > failing to remove nonexistent files.  But we just tested that the file
>> > exists, and in the impossible even of a race making it not exist by
>> > the time that it runs, we have more problems than the failure of rm
>> > since we use the file's existence as a control for other things.
>> >
>> > So the only effect of this -f is to turn off -i, which can only be set
>> > if the FUD was justified.
>> >
>> > The correct fix seems to be 'unalias -a'.
>> >
>> > Bruce
>> >
>