PHP's open_basedir feature is meant to disallow scripts to access files outside a set of configured base directories. The checks for this are placed within PHP functions dealing with files before the actual open call is performed. Obviously there is a little span of time between the check and the actual open call. During this time span the checked path could have been altered and point to a file that is forbidden to be accessed due to open_basedir restrictions. Because the open_basedir restrictions often not call PHP functions but 3rd party library functions to actually open the file it is impossible to close this time span in a general way. It would only be possible to close it when PHP handles the actual opening on it's own. While it seems hard to change the path during this little time span it is very simple with the use of the symlink() function combined with a little trick. PHP's symlink() function ensures that source and target of the symlink operation are allowed by open_basedir restrictions (and safe_mode). However it is possible to point a symlink to any file by the use of mkdir(), unlink() and at least two symlinks. http://www.hardened-php.net/advisory_082006.132.html
I do not think that there is anything we can do about this, apart from either enabling Suhosin by default or disabling the symlink() function by default.
Reassigning to us only because security doesn't handle safe_mode/open_basedir bypasses... (In reply to comment #1) > apart from either enabling Suhosin by default Won't happen, we'll use this bug to quicken introduction of Suhosin a little in the tree, but it will always be only an additional option. > disabling the symlink() function by default. As upstream won't do this, we won't too (stay close to upstream paradigm). I also have no idea of how many things this would break... And well, open_basedir is not something you should rely on for security, good old Unix permissions still do a much better work of granting or denying access to stuff. ;) Best regards, CHTEKK.
i think this issue is fixed in 4.4.5, see bug 167028
Suhosin is in the tree and will be stabled soon, see bug 153911 for progress. Best regards, CHTEKK.
