Re: [PATCH] implement privmode support in dash

[Roy <roytam () gmail com>]

On Fri, 23 Aug 2013 19:40:31 +0800, "Jérémie Courrèges-Anglas"  
<jca+dash () wxcvbn org> wrote:

> Also,
>
> Tavis Ormandy <taviso () google com> writes:
>
> [...]
>
> > > Apart from that, it is better to check the return value from setuid()
> > > and similar functions. In particular, some versions of Linux may fail
> > > setuid() for [EAGAIN], leaving the process running with the same
> > > privileges.
> >
> > I don't think this is true anymore, but I have no strong objection to
> > adding it, so long as it's noted that bash and pdksh do not do this.
>
> Just for reference, from mksh:

[snip]

BTW it is just changed in cvs. Log message:

Commit ID:      10052176CB912FE954B
CVSROOT:        /cvs
Module name:    src
Changes by:     tg () herc mirbsd org   2013/08/23 14:07:41
UTC

Modified files:
        distrib/special/mksh: Makefile
        bin/mksh       : Build.sh Makefile check.t misc.c mksh.1 sh.h

Log message:
SECURITY: Unbreak “set +p”, broken by OpenBSD ksh change.

TODO: I am seriously considering following Chet and changing
the way this works, by explicitly dropping privs unless the
shell is run with -p. Every other shell does it like mksh,
except Heirloom sh, which on the other hand doesn’t know any
explicit set -p or set +p (though it doesn’t know set +foo
for any foo either).

┌──┤ QUESTION: Do we need the ability to do this:
│ tg@blau:~ $ ./suidmksh -p -c 'whoami; set +p; whoami'
│ root
│ tg

If not, I’m seriously considering to drop set ±p as well,
only parse -p on the command line, with +p being the default,
and dropping FPRIVILEGED.

Thanks to RT for noticing and jilles for initial follow-up
discussion, as well as Chet Ramey for doing the sane/secure
thing instead of following Debian.

To generate a diff of this changeset, execute the following commands:
cvs -R rdiff -kk -upr1.71 -r1.72 src/distrib/special/mksh/Makefile
cvs -R rdiff -kk -upr1.645 -r1.646 src/bin/mksh/Build.sh
cvs -R rdiff -kk -upr1.124 -r1.125 src/bin/mksh/Makefile
cvs -R rdiff -kk -upr1.630 -r1.631 src/bin/mksh/check.t
cvs -R rdiff -kk -upr1.214 -r1.215 src/bin/mksh/misc.c
cvs -R rdiff -kk -upr1.320 -r1.321 src/bin/mksh/mksh.1
cvs -R rdiff -kk -upr1.668 -r1.669 src/bin/mksh/sh.h