> On Sep 29, 2018, at 3:34 AM, Aleksa Sarai <cyphar@xxxxxxxxxx> wrote: > > The need for some sort of control over VFS's path resolution (to avoid > malicious paths resulting in inadvertent breakouts) has been a very > long-standing desire of many userspace applications. This patchset is a > revival of Al Viro's old AT_NO_JUMPS[1] patchset with a few additions. > > The most obvious change is that AT_NO_JUMPS has been split as dicussed > in the original thread, along with a further split of AT_NO_PROCLINKS > which means that each individual property of AT_NO_JUMPS is now a > separate flag: > > * Path-based escapes from the starting-point using "/" or ".." are > blocked by AT_BENEATH. Seems useful. > * Mountpoint crossings are blocked by AT_XDEV. Seems useful. > * /proc/$pid/fd/$fd resolution is blocked by AT_NO_PROCLINKS (more > correctly it actually blocks any user of nd_jump_link() because it > allows out-of-VFS path resolution manipulation). > So how do I disable following symlinks? ISTM the most natural way would be to have AT_NO_SYMLINKS, and to have that flag disable proc links.
