GIT, SSH, and GIT-SHELL

You will find a similar mechanism with gitolite, based on ssh and forced command.
(including ldap queries).
It don't allow interactive shell however, which could be your issue there.

The OP Frank Brenner adds:

Ah, I figured it out - the command has to be in single quotes. I suppose $SSH_ORIGINAL_COMMAND was getting expanded before git-shell was started.

That is confirmed in the gitolite forced command script is a Perl one, ending with:

# ----------------------------------------------------------------------------
#       over to git now
# ----------------------------------------------------------------------------

if ($ENV{REQUEST_URI}) {
    log_it($ENV{REQUEST_URI});
    exec $ENV{GIT_HTTP_BACKEND};
    # the GIT_HTTP_BACKEND env var should be set either by the rc file, or as
    # a SetEnv in the apache config somewhere
}

log_it();

$repo = "'$REPO_BASE/$repo.git'";
exec("git", "shell", "-c", "$verb $repo") unless $verb eq 'git-init';

Note the $repo = "'$REPO_BASE/$repo.git'" line: it does contains single quotes.

I've made a solution using LDAP, OpenSSH (>4.9) and git-shell.

OpenSSH's ForceCommand is perfect for the job. Consider the following configuration (everyone except admins have to use git-shell):

Match group *,!admin    
    ForceCommand /usr/bin/git-shell -c "$SSH_ORIGINAL_COMMAND"

Access control is defined using ACL-s and reponame access groups.

setfacl -bR -m default:group:$REPONAME:rwX -m group:$REPONAME:rwX $GITROOT/$REPONAME
setfacl -R -m default:group:$REPONAME-ro:r-X -m group:$REPONAME-ro:r-X $GITROOT/$REPONAME

Don't forget to run "nscd -i group", after each change.

Andor