Answer: fs.protected_hardlinks=1 is what prevents the creation of hardlinks to files you don't own. It's on by default on all machines I checked though. https:

Answer: fs.protected_hardlinks=1 is what prevents the creation of hardlinks to files you don't own. It's on by default on all machines I checked though. https://github.com/torvalds/linux/commit/800179c9b8a1e796e441674776d11cd4c05d61d7 https://github.com/torvalds/linux/commit/800179c9b8a1e796e44... Without this, a whole lot of attacks are possible with hardlinks.