On Tue, Apr 05, 2016 at 03:54:25AM +0100, Al Viro wrote: > That, I take it, is a lookup for .. and buggering off if it fails *or* if > we had been in caller's root or something that overmount it? Not that the > latter had been possible - root is a directory and can be overmounted only > by another such, and we are called from ->open() of a device node. > > > + /* Remember the result of this permission check for later */ > > + ret = inode_permission(path.dentry->d_inode, MAY_EXEC); > > + if (path_pts(&path)) > > + goto fail; > > Egads, man - you've just introduced a special function for looking up > something named "pts" in a given directory! > > The reason not to use kern_path() would be what, the fact that it doesn't > allow starting at given location? So let's make a variant that would - and > rather than bothering with RCU, just go for something like (completely > untested)
Ah... Right, that would demand exec permissions on the starting point. Still, this is incredibly ugly ;-/ I'll try to come up with something more tolerable, but this "path_pts" thing is too ugly to live. Seriously.
