Mprotect stops any read and write and execute access to memory in both user and kernel lands (only rx or wx). Stuff like web browsers won’t work unless you have a program to mark it in elf to not use pax. However, this kills a lot of exploits with that turned on by itself (though there are probably work arounds if you are developing exploits which the other features would hopefully catch). That’s why people installed 3rd party unmainlined security patches, but that’s just me maybe idk.
I am having a hard time following what this does or why this is desirable. You’re saying there’s a patch this thing provides that … disables memory access … unless a flag is set in an executable … which will then bypass the security?
Yup. You can only add the nopax flag as root, so if your system is already hosed, not much else you can protect. Root has access to ring 0 so anything goes with access like that. Stuff like pax would slow them down for sure and stop script kiddies, but root access is root access.
No privileged accounts can’t do anything with the nopax flag. That’s why you should configure your system to not run things as root as much as possible. Personally; on desktops, I don’t even use a sudoer natively. I have to su into my sudoer account in order to run root commands.
