Re: Avoid sourcing bashrc when connected to sockets

[Chet Ramey]

On 2/21/22 2:15 PM, Andrew Gregory wrote:
> On 02/21/22 at 02:01pm, Greg Wooledge wrote:
> > On Mon, Feb 21, 2022 at 10:31:21AM -0800, Andrew Gregory wrote:
> > > On 02/14/22 at 11:11am, Chet Ramey wrote:
> > > > You might also want to tell your vendor about this, since they built bash
> > > > with the non-standard option that enables this behavior.
> > >
> > > Can you explain this?  Looking at the package build script[1] and the bash
> > > source, nothing stands out to me as specifically enabling this behavior.
> >
> > I don't know Arch, but Debian does it by applying a patch:
> >
> > https://sources.debian.org/src/bash/5.1-2/debian/patches/deb-bash-config.diff/
> >
> > The last piece of that patch sets the SSH_SOURCE_BASHRC macro in the
> > config-top.h file, which is what enables the feature.  I would guess
> > that Arch does something similar, with whatever system of source code
> > patches it uses.
>
> Hmmm, that appears to be a different check, specific to ssh.  That shouldn't be
> what we're hitting.

It doesn't appear so.

>  I believe we're hitting the isnetconn check below it,
> which doesn't appear to be behind a configure option that I can see.

It's not.

The original reason for the SSH_CLIENT check (it dates from 1997) was that
sshd ran its children with their stdin and stdout connected to pipes, so
the isnetconn() check would fail.

The reason it's a configurable option is that checking for SSH_CLIENT can
fail and cause the bashrc to be read under circumstances other than being
run directly by sshd, like when `make' runs `$SHELL -c command' and doesn't
pass SHLVL through the environment (or it wasn't there to begin with), but 
SSH_CLIENT is present in the environment.

Clearly times have changed, and maybe it's time to revisit that piece of
code.

We might be able to get rid of the SSH_CLIENT check for good. That doesn't
help you with your problem, of course.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/