Re: [PATCH 1/3] fs: add O_BENEATH flag to openat(2)
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: 2014-11-03 15:20:41
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On Mon, Nov 03, 2014 at 11:48:23AM +0000, David Drysdale wrote:
Add a new O_BENEATH flag for openat(2) which restricts the provided path, rejecting (with -EACCES) paths that are not beneath the provided dfd. In particular, reject: - paths that contain .. components - paths that begin with / - symlinks that have paths as above.
Yecch... The degree of usefulness aside (and I'm not convinced that it is non-zero), WTF pass one bit out of nameidata->flags in a separate argument? Through the mutual recursion, no less... And then you are not even attempting to detect symlinks that are not followed by interpretation of _any_ pathname.