Al Viro <v...@zeniv.linux.org.uk> writes: > 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.
Given that I can think of no other reason than this special case to ever want to use this code. I figured having something incredibily special case and obviously so was the way to go. Then at least no one would mistake it for a general purpose facility. Eric
