Hi, If /tmp/XWin.log is a symlink, XWin will merrily follow it and write to whatever it's pointing to (see LogInit() in os/log.c). This allows standard symlink-following attacks.
Example: Alice runs "ln -s /home/Bob/phd-thesis.tex /tmp/XWin.log" under her account. Later Bob runs XWin under his account; XWin fails for some reasons and writes to /tmp/XWin.log; Bob life's work gets overwritten. (Of course, that's interesting only if ntsec is used.) Some possible fixes: * Place the logfile somewhere in the user's home directory. * Refuse to follow symlinks, or to write to existing files. Most users, failing to clean up logs, will not get new logs after the first failure. * Give the logfile a unique filename, a la the "uniq" utility. Eran
