Re: identity confusion

[Wayne Sallee]

-------- Original Message -------- *Subject: *  Re: identity confusion *From: *     Tomas <to...@tuxteam.de> *To: *         Debian-user <debian-user@lists.debian.org> *CC: *         *Date: *      2020-1-24  03:44 AM On Thu, Jan 23, 2020 at 06:11:37PM -0500, Wayne Sallee wrote: This is interesting. I'm not sure what to think about this. on terminal, as user1 su - # Enter root password. su - user2 # No password is needed. mysql Access denied for user 'user1'@'localhost' (using password: NO) After your (first) "su -" and your (second) "su - user2", just issue the command "id": this might help understand what's going on (my hunch is that (real) uid and euid are not identical at that point, but I might be wrong, see below). # Now if I enter: mysql -u user2 -pmypassword # It will let me in. I have no idea where the "mysql" command tries to get its default user ID from (probably out of one of the several possible user IDs [1] your shell process has, but Who Knows (TM)?) If you override that (with -u) and prove you have access rights (by providing your password, with -p) it doesn't have to guess. What surprises me, is that it figures that user1 is wanting access to mysql instead of user2 Knowing a previous user, could have security issues. Read [1] below. You have control over the session. You "came from" user1. Why should that be a problem? OTOH perhaps mysql is basing its guess on the environment variable LOGNAME, and "su -" hasn't changed that? It's ages ago I stopped using "su" regularly (convinced by sudo), so I lost track of the finer details of "su" (which have changed recently, AFAIK). Cheers [1] https://en.wikipedia.org/wiki/User_identifier -- tomás Thanks for the ideas. id echo $LOGNAME both are normal. I also looked at: printenv set echo $USER It's not a big security threat, but sometimes a small bug like that can end up being a security threat under the right circumstances. And sometimes a bug like that can end up being bigger than first realized. Wayne Sallee wa...@waynesallee.com http://www.WayneSallee.com