On 09 Jul 2016, at 13:01, UNIX admin <tripivceta@gmail.com> wrote:
Hello list
I want to implement override_username = %variable for the "shadow" driver, so that the following works:
passdb { driver = shadow args = override_username=%Ln }
by "%variable", I mean "Variables" at http://wiki.dovecot.org/Variables.
I've hacked up a solution with strtok(3C), but that's a hack and a possible security hole, and I'd rather not implement it. What I really want is to be able to leverage Dovecot's var_expand() call, which, looking at the code, appears to be the function responsible for %variable expansion and formatting.
The relevant piece of code seems to be this excerpt in auth/passdb-shadow.c:
static enum passdb_result shadow_lookup(struct auth_request *request, struct spwd **spw_r) { auth_request_log_debug(request, AUTH_SUBSYS_DB, "lookup");
*spw_r = getspnam(request->user); if (*spw_r == NULL) { auth_request_log_unknown_user(request, AUTH_SUBSYS_DB); return PASSDB_RESULT_USER_UNKNOWN; }when request->user contains 'user@domain.tld', I want the code to be able to process "override_username", determine that the format is %Ln so that request->user is lowercased, and everything after the "@" sign is stripped. Therefore, if this user happens to exist in the shadow file, authentication will succeed.
Currently, the "shadow" driver only appears to support "args = blocking=no".
You need this to be specific to the one passdb, not everything? So auth_username_format=%Ln setting wouldn't work?
passwd-file driver has username_format parameter, which does this. I've thought that rather than copy&pasting such code to other drivers, the next step would be to make it work for all the passdb and userdb drivers, such as:
passdb { driver = anything args = anything username_format = %Ln }
I'd be happy for such a generic patch. I'm not entirely sure what's the best/nicest way to do it though. Maybe temporarily override auth_request->user? Could be ugly, but maybe doable..